Dual Role of Natural Killer Cells in Early Pregnancy: Immunopathological Implications and Therapeutic Potential in Recurrent Spontaneous Abortion and Recurrent Implantation Failure

Abstract

Natural killer (NK) cells are critical regulators of immune processes during early pregnancy, playing a key role in maintaining maternal-foetal immune tolerance and supporting successful implantation. In particular, uterine NK cells, a specialised subset of NK cells, facilitate trophoblast invasion, spiral artery remodelling and placental establishment. Dysregulation of NK cell activity, however, has been implicated in pregnancy complications, notably recurrent spontaneous abortion (RSA) and recurrent implantation failure (RIF). Aberrant NK cell functions, such as heightened cytotoxicity or defective immune signalling, can disrupt the balance between immune tolerance and response, leading to impaired placental development, reduced trophoblast activity and compromised uteroplacental blood flow. This review examines the role of NK cells in early pregnancy, emphasising their contributions to immune modulation and placentation. It also investigates the mechanisms by which NK cell dysfunction contributes to RSA and RIF, and explores therapeutic strategies aimed at restoring NK cell balance to improve pregnancy outcomes. A deeper understanding of NK cell interactions during early pregnancy may provide critical insights into the pathogenesis of pregnancy failure and facilitate targeted immunotherapeutic approaches.

Keywords

molecular mechanisms / natural killer cell / recurrent implantation failure / recurrent spontaneous abortion / targeted therapy

References

[1] Y. Shi, B. Ling, Y. Zhou, et al., “Interferon-Gamma Expression in Natural Killer Cells and Natural Killer T Cells Is Suppressed in Early Pregnancy,” Cellular & Molecular Immunology 4, no. 5 (2007): 389-394.

[2] C. Carlino, H. Stabile, S. Morrone, et al., “Recruitment of Circulating NK Cells Through Decidual Tissues: A Possible Mechanism Controlling NK Cell Accumulation in the Uterus During Early Pregnancy,” Blood 111, no. 6 (2008): 3108-3115.

[3] E. Von Woon, O. Greer, N. Shah, D. Nikolaou, M. Johnson, and V. Male, “Number and Function of Uterine Natural Killer Cells in Recurrent Miscarriage and Implantation Failure: A Systematic Review and Meta-Analysis,” Human Reproduction Update 28, no. 4 (2022): 548-582, https://doi.org/10.1093/humupd/dmac006.

[4] M. J. van den Heuvel, S. Chantakru, X. Xuemei, et al., “Trafficking of Circulating Pro-NK Cells to the Decidualizing Uterus: Regulatory Mechanisms in the Mouse and Human,” Immunological Investigations 34, no. 3 (2005): 273-293, https://doi.org/10.1081/imm-200064488.

[5] A. Dixit and A. A. Karande, “Glycodelin Regulates the Numbers and Function of Peripheral Natural Killer Cells,” Journal of Reproductive Immunology 137 (2020): 102625.

[6] J. P. Goodridge, L. J. Lathbury, E. John, A. K. Charles, F. T. Christiansen, and C. S. Witt, “The Genotype of the NK Cell Receptor, KIR2DL4, Influences INFgamma Secretion by Decidual Natural Killer Cells,” Molecular Human Reproduction 15, no. 8 (2009): 489-497.

[7] D.-D. Li, W.-H. Ji, D.-P. Wei, et al., “Cytochrome P450 26A1 Regulates the Clusters and Killing Activity of NK Cells During the Peri-Implantation Period,” Journal of Cellular and Molecular Medicine 26, no. 8 (2022): 2438-2450.

[8] M. Bourdon, A. S. Maget, M. Jeljeli, et al., “Reduced Fertility in an Adenomyosis Mouse Model Is Associated With an Altered Immune Profile in the Uterus During the Implantation Period,” Human Reproduction 39, no. 1 (2024): 119-129.

[9] Z. Fang, J. Mao, J. Huang, et al., “Increased Levels of Villus-Derived Exosomal miR-29a-3p in Normal Pregnancy Than uRPL Patients Suppresses Decidual NK Cell Production of Interferon-γ and Exerts a Therapeutic Effect in Abortion-Prone Mice,” Cell Communication and Signaling: CCS 22, no. 1 (2024): 230.

[10] R. Takeyama, A. Fukui, C. Mai, et al., “Co-Expression of NKp46 With Activating or Inhibitory Receptors on, and Cytokine Production by, Uterine Endometrial NK Cells in Recurrent Pregnancy Loss,” Journal of Reproductive Immunology 145 (2021): 103324, https://doi.org/10.1016/j.jri.2021.103324.

[11] P. Vacca, C. Cantoni, M. Vitale, et al., “Crosstalk Between Decidual NK and CD14+ Myelomonocytic Cells Results in Induction of Tregs and Immunosuppression,” Proceedings of the National Academy of Sciences of the United States of America 107, no. 26 (2010): 11918-11923.

[12] P. Vacca, M. C. Mingari, and L. Moretta, “Natural Killer Cells in Human Pregnancy,” Journal of Reproductive Immunology 97, no. 1 (2013): 14-19.

[13] L. Arruvito, S. Giulianelli, A. C. Flores, et al., “NK Cells Expressing a Progesterone Receptor Are Susceptible to Progesterone-Induced Apoptosis,” Journal of Immunology 180, no. 8 (2008): 5746-5753, https://doi.org/10.4049/jimmunol.180.8.5746.

[14] C. Fauriat, M. A. Ivarsson, H.-G. Ljunggren, K.-J. Malmberg, and J. Michaëlsson, “Education of Human Natural Killer Cells by Activating Killer Cell Immunoglobulin-Like Receptors,” Blood 115, no. 6 (2010): 1166-1174.

[15] L.-N. Duan, H.-X. Han, J. Liu, et al., “Impact of Incompatible Killer Cell Immunoglobulin-Like Receptor and Its Ligand on the Outcome of Haploidentical Bone Marrow Transplantation,” Zhongguo Shi Yan Xue Ye Xue Za Zhi 15, no. 4 (2007): 809-815.

[16] Z. B. Davis, A. Cogswell, H. Scott, et al., “A Conserved HIV-1-Derived Peptide Presented by HLA-E Renders Infected T-Cells Highly Susceptible to Attack by NKG2A/CD94-Bearing Natural Killer Cells,” PLoS Pathogens 12, no. 2 (2016): e1005421.

[17] A. Myles, A. Tuteja, and A. Aggarwal, “Synovial Fluid Mononuclear Cell Gene Expression Profiling Suggests Dysregulation of Innate Immune Genes in Enthesitis-Related Arthritis Patients,” Rheumatology (Oxford, England) 51, no. 10 (2012): 1785-1789.

[18] D. A. Vargas-Inchaustegui, T. Demberg, and M. Robert-Guroff, “A CD8α(−) Subpopulation of Macaque Circulatory Natural Killer Cells Can Mediate Both Antibody-Dependent and Antibody-Independent Cytotoxic Activities,” Immunology 134, no. 3 (2011): 326-340.

[19] S. M. Maloveste, D. Chen, E. Gostick, et al., “Degenerate Recognition of MHC Class I Molecules With Bw4 and Bw6 Motifs by a Killer Cell Ig-Like Receptor 3DL Expressed by Macaque NK Cells,” Journal of Immunology 189, no. 9 (2012): 4338-4348, https://doi.org/10.4049/jimmunol.1201360.

[20] A. Alok and A. A. Karande, “The Role of Glycodelin as an Immune-Modulating Agent at the Feto-Maternal Interface,” Journal of Reproductive Immunology 83, no. 1-2 (2009): 124-127.

[21] Y. Hidaka, N. Amino, Y. Iwatani, et al., “Changes in Natural Killer Cell Activity in Normal Pregnant and Postpartum Women: Increases in the First Trimester and Postpartum Period and Decrease in Late Pregnancy,” Journal of Reproductive Immunology 20, no. 1 (1991): 73-83.

[22] M. R. Verneris and J. S. Miller, “The Phenotypic and Functional Characteristics of Umbilical Cord Blood and Peripheral Blood Natural Killer Cells,” British Journal of Haematology 147, no. 2 (2009): 185-191.

[23] P. Wang, T. Liang, H. Zhan, et al., “Unique Metabolism and Protein Expression Signature in Human Decidual NK Cells,” Frontiers in Immunology 14 (2023): 1136652, https://doi.org/10.3389/fimmu.2023.1136652.

[24] P. J. Williams, R. F. Searle, S. C. Robson, B. A. Innes, and J. N. Bulmer, “Decidual Leucocyte Populations in Early to Late Gestation Normal Human Pregnancy,” Journal of Reproductive Immunology 82, no. 1 (2009): 24-31.

[25] B. Fu, Z. Tian, and H. Wei, “Subsets of Human Natural Killer Cells and Their Regulatory Effects,” Immunology 141, no. 4 (2014): 483-489.

[26] K. Karimi, M. E. Solano, A. A. Ashkar, et al., “Regulation of Pregnancy Maintenance and Fetal Survival in Mice by CD27(Low) Mature NK Cells,” Journal of Molecular Medicine (Berlin, Germany) 90, no. 9 (2012): 1047-1057.

[27] C. Carlino, E. Trotta, H. Stabile, et al., “Chemerin Regulates NK Cell Accumulation and Endothelial Cell Morphogenesis in the Decidua During Early Pregnancy,” Journal of Clinical Endocrinology and Metabolism 97, no. 10 (2012): 3603-3612.

[28] P. M. Drake, M. D. Gunn, I. F. Charo, et al., “Human Placental Cytotrophoblasts Attract Monocytes and CD56 (Bright) Natural Killer Cells via the Actions of Monocyte Inflammatory Protein 1alpha,” Journal of Experimental Medicine 193, no. 10 (2001): 1199-1212.

[29] K. Kitaya, T. Nakayama, T. Okubo, H. Kuroboshi, S. Fushiki, and H. Honjo, “Expression of Macrophage Inflammatory Protein-1beta in Human Endometrium: Its Role in Endometrial Recruitment of Natural Killer Cells,” Journal of Clinical Endocrinology and Metabolism 88, no. 4 (2003): 1809-1814.

[30] R. H. Choudhury, C. E. Dunk, S. J. Lye, J. D. Aplin, L. K. Harris, and R. L. Jones, “Extravillous Trophoblast and Endothelial Cell Crosstalk Mediates Leukocyte Infiltration to the Early Remodeling Decidual Spiral Arteriole Wall,” Journal of Immunology 198, no. 10 (2017): 4115-4128.

[31] X. Wu, L.-P. Jin, M.-M. Yuan, Y. Zhu, M.-Y. Wang, and D.-J. Li, “Human First-Trimester Trophoblast Cells Recruit CD56brightCD16- NK Cells Into Decidua by Way of Expressing and Secreting of CXCL12/Stromal Cell-Derived Factor 1,” Journal of Immunology 175, no. 1 (2005): 61-68.

[32] J. Hanna, O. Wald, D. Goldman-Wohl, et al., “CXCL12 Expression by Invasive Trophoblasts Induces the Specific Migration of CD16- Human Natural Killer Cells,” Blood 102, no. 5 (2003): 1569-1577.

[33] J. Han, M. J. Gu, I. Yoo, et al., “Analysis of Cysteine-X-Cysteine Motif Chemokine Ligands 9, 10, and 11, Their Receptor CXCR3, and Their Possible Role on the Recruitment of Immune Cells at the Maternal-Conceptus Interface in Pigs,” Biology of Reproduction 97, no. 1 (2017): 69-80.

[34] C. J. Lockwood, S. J. Huang, C.-P. Chen, et al., “Decidual Cell Regulation of Natural Killer Cell-Recruiting Chemokines: Implications for the Pathogenesis and Prediction of Preeclampsia,” American Journal of Pathology 183, no. 3 (2013): 841-856.

[35] G. Schofield and S. J. Kimber, “Leukocyte Subpopulations in the Uteri of Leukemia Inhibitory Factor Knockout Mice During Early Pregnancy,” Biology of Reproduction 72, no. 4 (2005): 872-878.

[36] L. Chiossone, P. Vacca, P. Orecchia, et al., “In Vivo Generation of Decidual Natural Killer Cells From Resident Hematopoietic Progenitors,” Haematologica 99, no. 3 (2014): 448-457.

[37] K. Kusama, M. Yoshie, K. Tamura, et al., “Regulation of Decidualization in Human Endometrial Stromal Cells Through Exchange Protein Directly Activated by Cyclic AMP (Epac),” Placenta 34, no. 3 (2013): 212-221.

[38] X. Jin, L. Cui, W. Zhao, et al., “Decidualization-Derived cAMP Regulates Phenotypic and Functional Conversion of Decidual NK Cells From CD56dimCD16- NK Cells,” Cellular & Molecular Immunology 18, no. 6 (2021): 1596-1598.

[39] A. A. Ashkar, G. P. Black, Q. Wei, et al., “Assessment of Requirements for IL-15 and IFN Regulatory Factors in Uterine NK Cell Differentiation and Function During Pregnancy,” Journal of Immunology 171, no. 6 (2003): 2937-2944.

[40] B. Strunz, J. Bister, H. Jönsson, et al., “Continuous Human Uterine NK Cell Differentiation in Response to Endometrial Regeneration and Pregnancy,” Science Immunology 6, no. 56 (2021): eabb7800.

[41] S. Verma, S. E. Hiby, Y. W. Loke, and A. King, “Human Decidual Natural Killer Cells Express the Receptor for and Respond to the Cytokine Interleukin 15,” Biology of Reproduction 62, no. 4 (2000): 959-968.

[42] K. Kitaya and T. Yasuo, “Regulatory Role of Membrane-Bound Form Interleukin-15 on Human Uterine Microvascular Endothelial Cells in Circulating CD16(−) Natural Killer Cell Extravasation Into Human Endometrium,” Biology of Reproduction 89, no. 3 (2013): 70.

[43] Y.-O. Ahn, B. R. Blazar, J. S. Miller, and M. R. Verneris, “Lineage Relationships of Human Interleukin-22-Producing CD56+ RORγt+ Innate Lymphoid Cells and Conventional Natural Killer Cells,” Blood 121, no. 12 (2013): 2234-2243.

[44] M. D. Boos, Y. Yokota, G. Eberl, and B. L. Kee, “Mature Natural Killer Cell and Lymphoid Tissue-Inducing Cell Development Requires Id2-Mediated Suppression of E Protein Activity,” Journal of Experimental Medicine 204, no. 5 (2007): 1119-1130.

[45] T. Ikawa, S. Fujimoto, H. Kawamoto, Y. Katsura, and Y. Yokota, “Commitment to Natural Killer Cells Requires the Helix-Loop-Helix Inhibitor Id2,” Proceedings of the National Academy of Sciences of the United States of America 98, no. 9 (2001): 5164-5169.

[46] R. B. Delconte, W. Shi, P. Sathe, et al., “The Helix-Loop-Helix Protein ID2 Governs NK Cell Fate by Tuning Their Sensitivity to Interleukin-15,” Immunity 44, no. 1 (2016): 103-115.

[47] J. Rautela, L. F. Dagley, T. Kratina, et al., “Generation of Novel Id2 and E2-2, E2A and HEB Antibodies Reveals Novel Id2 Binding Partners and Species-Specific Expression of E-Proteins in NK Cells,” Molecular Immunology 115 (2019): 56-63.

[48] R. Schotte, W. Dontje, M. Nagasawa, et al., “Synergy Between IL-15 and Id2 Promotes the Expansion of Human NK Progenitor Cells, Which Can Be Counteracted by the E Protein HEB Required to Drive T Cell Development,” Journal of Immunology 184, no. 12 (2010): 6670-6679, https://doi.org/10.4049/jimmunol.0901508.

[49] R. Ma, N. Jin, H. Lei, et al., “Ovarian Stimulation in Mice Resulted in Abnormal Placentation Through Its Effects on Proliferation and Cytokine Production of Uterine NK Cells,” International Journal of Molecular Sciences 24, no. 6 (2023): 5907, https://doi.org/10.3390/ijms24065907.

[50] A. King, L. Gardner, and Y. W. Loke, “Co-Stimulation of Human Decidual Natural Killer Cells by Interleukin-2 and Stromal Cells,” Human Reproduction 14, no. 3 (1999): 656-663.

[51] R. Ain, M.-L. Trinh, and M. J. Soares, “Interleukin-11 Signaling Is Required for the Differentiation of Natural Killer Cells at the Maternal-Fetal Interface,” Developmental Dynamics 231, no. 4 (2004): 700-708.

[52] J. Siewiera, J. Gouilly, H.-R. Hocine, et al., “Natural Cytotoxicity Receptor Splice Variants Orchestrate the Distinct Functions of Human Natural Killer Cell Subtypes,” Nature Communications 6 (2015): 10183.

[53] M. Han, L. Hu, D. Wu, et al., “IL-21R-STAT3 Signalling Initiates a Differentiation Program in Uterine Tissue-Resident NK Cells to Support Pregnancy,” Nature Communications 14, no. 1 (2023): 7109.

[54] H.-L. Yang, W.-J. Zhou, H. Lu, et al., “Decidual Stromal Cells Promote the Differentiation of CD56bright CD16- NK Cells by Secreting IL-24 in Early Pregnancy,” American Journal of Reproductive Immunology 81, no. 6 (2019): e13110.

[55] D. B. Keskin, D. S. J. Allan, B. Rybalov, et al., “TGFbeta Promotes Conversion of CD16+ Peripheral Blood NK Cells Into CD16- NK Cells With Similarities to Decidual NK Cells,” Proceedings of the National Academy of Sciences of the United States of America 104, no. 9 (2007): 3378-3383.

[56] X. Xu, Y. Zhou, B. Fu, et al., “PBX1 Promotes Development of Natural Killer Cells by Binding Directly to the Nfil3 Promoter,” FASEB Journal 34, no. 5 (2020): 6479-6492.

[57] X. An, J. Qin, X. Hu, Y. Zhou, B. Fu, and H. Wei, “Overexpression of Lipocalin 2 in PBX1-Deficient Decidual NK Cells Promotes Inflammation at the Maternal-Fetal Interface,” American Journal of Reproductive Immunology 89, no. 3 (2023): e13676.

[58] A. Sliz, K. C. S. Locker, K. Lampe, et al., “Gab3 Is Required for IL-2- and IL-15-Induced NK Cell Expansion and Limits Trophoblast Invasion During Pregnancy,” Science Immunology 4, no. 38 (2019): eaav3866.

[59] T. G. Burnett and J. S. Hunt, “Nitric Oxide Synthase-2 and Expression of Perforin in Uterine NK Cells,” Journal of Immunology 164, no. 10 (2000): 5245-5250.

[60] X. Qin, X. Liu, B. Shan, et al., “Inhibition of eIF5A Results in Aberrant Uterine Natural Killer Cell Function and Embryo Loss in Mice,” American Journal of Reproductive Immunology 71, no. 3 (2014): 229-240, https://doi.org/10.1111/aji.12194.

[61] A. M. Felker and B. A. Croy, “Natural Cytotoxicity Receptor 1 in Mouse uNK Cell Maturation and Function,” Mucosal Immunology 10, no. 5 (2017): 1122-1132.

[62] S. Kamizono, G. S. Duncan, M. G. Seidel, et al., “Nfil3/E4bp4 Is Required for the Development and Maturation of NK Cells In Vivo,” Journal of Experimental Medicine 206, no. 13 (2009): 2977-2986.

[63] D. M. Gascoyne, E. Long, H. Veiga-Fernandes, et al., “The Basic Leucine Zipper Transcription Factor E4BP4 Is Essential for Natural Killer Cell Development,” Nature Immunology 10, no. 10 (2009): 1118-1124.

[64] T. Kostrzewski, A. J. Borg, Y. Meng, et al., “Multiple Levels of Control Determine How E4bp4/Nfil3 Regulates NK Cell Development,” Journal of Immunology 200, no. 4 (2018): 1370-1381.

[65] C.-L. Lee, M. Vijayan, X. Wang, et al., “Glycodelin-A Stimulates the Conversion of Human Peripheral Blood CD16-CD56bright NK Cell to a Decidual NK Cell-Like Phenotype,” Human Reproduction 34, no. 4 (2019): 689-701.

[66] O. Huhn, M. A. Ivarsson, L. Gardner, et al., “Distinctive Phenotypes and Functions of Innate Lymphoid Cells in Human Decidua During Early Pregnancy,” Nature Communications 11, no. 1 (2020): 381.

[67] D.-P. Wei, D.-D. Li, A.-Q. Gu, W.-H. Ji, Y. Yang, and J.-P. Peng, “A Novel Cytochrome P450 26A1 Expressing NK Cell Subset at the Mouse Maternal-Foetal Interface,” Journal of Cellular and Molecular Medicine 25, no. 3 (2021): 1771-1782.

[68] C.-Y. Meng, Z.-Y. Li, W.-N. Fang, et al., “Cytochrome P450 26A1 Modulates Natural Killer Cells in Mouse Early Pregnancy,” Journal of Cellular and Molecular Medicine 21, no. 4 (2017): 697-710.

[69] D. S. J. Allan, C. L. Kirkham, O. A. Aguilar, et al., “An In Vitro Model of Innate Lymphoid Cell Function and Differentiation,” Mucosal Immunology 8, no. 2 (2015): 340-351.

[70] P. Vacca, C. Cantoni, C. Prato, et al., “Regulatory Role of NKp44, NKp46, DNAM-1 and NKG2D Receptors in the Interaction Between NK Cells and Trophoblast Cells. Evidence for Divergent Functional Profiles of Decidual Versus Peripheral NK Cells,” International Immunology 20, no. 11 (2008): 1395-1405.

[71] L. N. Carayannopoulos, J. L. Barks, W. M. Yokoyama, and J. K. Riley, “Murine Trophoblast Cells Induce NK Cell Interferon-Gamma Production Through KLRK1,” Biology of Reproduction 83, no. 3 (2010): 404-414.

[72] L. Jiang, H. Fei, X. Jin, et al., “Extracellular Vesicle-Mediated Secretion of HLA-E by Trophoblasts Maintains Pregnancy by Regulating the Metabolism of Decidual NK Cells,” International Journal of Biological Sciences 17, no. 15 (2021): 4377-4395.

[73] M. P. Allen and M. Nilsen-Hamilton, “Granzymes D, E, F, and G Are Regulated Through Pregnancy and by IL-2 and IL-15 in Granulated Metrial Gland Cells,” Journal of Immunology 161, no. 6 (1998): 2772-2779.

[74] X. Zhang, L. Ding, Z. Diao, G. Yan, H. Sun, and Y. Hu, “CYR61 Modulates the Vascular Endothelial Growth Factor C Expression of Decidual NK Cells via PI3K/AKT Pathway,” American Journal of Reproductive Immunology 67, no. 3 (2012): 216-223.

[75] U. Fernekorn, E. C. Butcher, J. Behrends, S. Hartz, and A. Kruse, “Functional Involvement of P-Selectin and MAdCAM-1 in the Recruitment of alpha4beta7-Integrin-Expressing Monocyte-Like Cells to the Pregnant Mouse Uterus,” European Journal of Immunology 34, no. 12 (2004): 3423-3433.

[76] Y. Sagae, A. Horie, A. Yanai, et al., “Versican Provides the Provisional Matrix for Uterine Spiral Artery Dilation and Fetal Growth,” Matrix Biology 115 (2023): 16-31.

[77] O. Gubbay, H. O. D. Critchley, J. M. Bowen, A. King, and H. N. Jabbour, “Prolactin Induces ERK Phosphorylation in Epithelial and CD56(+) Natural Killer Cells of the Human Endometrium,” Journal of Clinical Endocrinology and Metabolism 87, no. 5 (2002): 2329-2335.

[78] P. Vacca, L. Moretta, A. Moretta, and M. C. Mingari, “Origin, Phenotype and Function of Human Natural Killer Cells in Pregnancy,” Trends in Immunology 32, no. 11 (2011): 517-523.

[79] A. E. Wallace, R. Fraser, S. Gurung, et al., “Increased Angiogenic Factor Secretion by Decidual Natural Killer Cells From Pregnancies With High Uterine Artery Resistance Alters Trophoblast Function,” Human Reproduction 29, no. 4 (2014): 652-660.

[80] R. Vento-Tormo, M. Efremova, R. A. Botting, et al., “Single-Cell Reconstruction of the Early Maternal-Fetal Interface in Humans,” Nature 563, no. 7731 (2018): 347-353.

[81] J. Hanna, D. Goldman-Wohl, Y. Hamani, et al., “Decidual NK Cells Regulate Key Developmental Processes at the Human Fetal-Maternal Interface,” Nature Medicine 12, no. 9 (2006): 1065-1074.

[82] D. K. Sojka, L. Yang, and W. M. Yokoyama, “Uterine Natural Killer Cells,” Frontiers in Immunology 10 (2019): 960.

[83] A. King, “Uterine Leukocytes and Decidualization,” Human Reproduction Update 6, no. 1 (2000): 28-36.

[84] N. Freitag, M. V. Zwier, G. Barrientos, et al., “Influence of Relative NK-DC Abundance on Placentation and Its Relation to Epigenetic Programming in the Offspring,” Cell Death & Disease 5, no. 8 (2014): e1392.

[85] B. Fu, X. Li, R. Sun, et al., “Natural Killer Cells Promote Immune Tolerance by Regulating Inflammatory TH17 Cells at the Human Maternal-Fetal Interface,” Proceedings of the National Academy of Sciences of the United States of America 110, no. 3 (2013): E231-E240, https://doi.org/10.1073/pnas.1206322110.

[86] I. Tirado-González, G. Barrientos, N. Freitag, et al., “Uterine NK Cells Are Critical in Shaping DC Immunogenic Functions Compatible With Pregnancy Progression,” PLoS One 7, no. 10 (2012): e46755.

[87] Z. Y. Li, H. H. Chao, H. Y. Liu, et al., “IFN-γ Induces Aberrant CD49b⁺ NK Cell Recruitment Through Regulating CX3CL1: A Novel Mechanism by Which IFN-γ Provokes Pregnancy Failure,” Cell Death & Disease 5, no. 11 (2014): e1512.

[88] A. L. Veenstra van Nieuwenhoven, A. Bouman, H. Moes, et al., “Cytokine Production in Natural Killer Cells and Lymphocytes in Pregnant Women Compared With Women in the Follicular Phase of the Ovarian Cycle,” Fertility and Sterility 77, no. 5 (2002): 1032-1037, https://doi.org/10.1016/S0015-0282(02)02976-X.

[89] F. Froehlich, K. Landerholm, J. Neeb, et al., “Emerging Role of C5aR2: Novel Insights Into the Regulation of Uterine Immune Cells During Pregnancy,” Frontiers in Immunology 15 (2024): 1411315.

[90] S.-L. Yang, H.-X. Tan, Z.-Z. Lai, et al., “An Active Glutamine/α-Ketoglutarate/HIF-1α Axis Prevents Pregnancy Loss by Triggering Decidual IGF1+GDF15+NK Cell Differentiation,” Cellular and Molecular Life Sciences 79, no. 12 (2022): 611.

[91] J.-W. Shi, H.-L. Yang, Z.-Z. Lai, et al., “WISP2/IGF1 Promotes the Survival of DSCs and Impairs the Cytotoxicity of Decidual NK Cells,” Reproduction 161, no. 4 (2021): 425-436, https://doi.org/10.1530/REP-20-0658.

[92] G. Meinhardt, L. Saleh, G. R. Otti, et al., “Wingless Ligand 5a Is a Critical Regulator of Placental Growth and Survival,” Scientific Reports 6 (2016): 28127.

[93] J. M. Monk, S. Leonard, B. A. McBey, and B. A. Croy, “Induction of Murine Spiral Artery Modification by Recombinant Human Interferon-Gamma,” Placenta 26, no. 10 (2005): 835-838.

[94] L. Ma, G. Li, G. Cao, et al., “dNK Cells Facilitate the Interaction Between Trophoblastic and Endothelial Cells via VEGF-C and HGF,” Immunology and Cell Biology 95, no. 8 (2017): 695-704.

[95] N. Meyer, K. Woidacki, M. Knöfler, et al., “Chymase-Producing Cells of the Innate Immune System Are Required for Decidual Vascular Remodeling and Fetal Growth,” Scientific Reports 7 (2017): 45106.

[96] X. Jin, L. Mao, W. Zhao, et al., “Decidualization-Derived cAMP Promotes Decidual NK Cells to Be Angiogenic Phenotype,” American Journal of Reproductive Immunology 88, no. 3 (2022): e13540.

[97] R. H. Choudhury, C. E. Dunk, S. J. Lye, L. K. Harris, J. D. Aplin, and R. L. Jones, “Decidual Leucocytes Infiltrating Human Spiral Arterioles Are Rich Source of Matrix Metalloproteinases and Degrade Extracellular Matrix In Vitro and In Situ,” American Journal of Reproductive Immunology 81, no. 1 (2019): e13054.

[98] E. M. Barber and J. W. Pollard, “The Uterine NK Cell Population Requires IL-15 but These Cells Are Not Required for Pregnancy nor the Resolution of a Listeria monocytogenes Infection,” Journal of Immunology 171, no. 1 (2003): 37-46.

[99] Y. Tao, Y.-H. Li, H.-L. Piao, et al., “CD56(Bright)CD25+ NK Cells Are Preferentially Recruited to the Maternal/Fetal Interface in Early Human Pregnancy,” Cellular & Molecular Immunology 12, no. 1 (2015): 77-86.

[100] M. Rabot, J. Tabiasco, B. Polgar, et al., “HLA Class I/NK Cell Receptor Interaction in Early Human Decidua Basalis: Possible Functional Consequences,” Chemical Immunology and Allergy 89 (2005): 72-83.

[101] F. Takei, K. L. McQueen, M. Maeda, et al., “Ly49 and CD94/NKG2: Developmentally Regulated Expression and Evolution,” Immunological Reviews 181, no. 1 (2001): 90-103, https://doi.org/10.1034/j.1600-065X.2001.1810107.x.

[102] D. Dukovska, D. Fernández-Soto, M. Valés-Gómez, and H. T. Reyburn, “NKG2H-Expressing T Cells Negatively Regulate Immune Responses,” Frontiers in Immunology 9, no. 390 (2018): 390, https://doi.org/10.3389/fimmu.2018.00390.

[103] M. Kusumi, T. Yamashita, T. Fujii, T. Nagamatsu, S. Kozuma, and Y. Taketani, “Expression Patterns of Lectin-Like Natural Killer Receptors, Inhibitory CD94/NKG2A, and Activating CD94/NKG2C on Decidual CD56bright Natural Killer Cells Differ From Those on Peripheral CD56dim Natural Killer Cells,” Journal of Reproductive Immunology 70, no. 1-2 (2006): 33-42.

[104] J. Zhang, C. E. Dunk, M. Kwan, et al., “Human dNK Cell Function Is Differentially Regulated by Extrinsic Cellular Engagement and Intrinsic Activating Receptors in First and Second Trimester Pregnancy,” Cellular & Molecular Immunology 14, no. 2 (2017): 203-213.

[105] L. Mincheva-Nilsson, O. Nagaeva, T. Chen, et al., “Placenta-Derived Soluble MHC Class I Chain-Related Molecules Down-Regulate NKG2D Receptor on Peripheral Blood Mononuclear Cells During Human Pregnancy: A Possible Novel Immune Escape Mechanism for Fetal Survival,” Journal of Immunology 176, no. 6 (2006): 3585-3592.

[106] Y. Ban, Y. Zhao, F. Liu, B. Dong, B. Kong, and X. Qu, “Effect of Indoleamine 2,3-Dioxygenase Expressed in HTR-8/SVneo Cells on Decidual NK Cell Cytotoxicity,” American Journal of Reproductive Immunology 75, no. 5 (2016): 519-528.

[107] S. T. Cox, R. Laza-Briviesca, H. Pearson, et al., “Umbilical Cord Blood Plasma Contains Soluble NKG2D Ligands That Mediate Loss of Natural Killer Cell Function and Cytotoxicity,” European Journal of Immunology 45, no. 8 (2015): 2324-2334, https://doi.org/10.1002/eji.201444990.

[108] Y. Wang and Y. Wang, “Palmitic Acid Upregulates CD96 Expression to Mediate Maternal-Foetal Interface Immune Tolerance by Inhibiting Cytotoxic Activity and Promoting Adhesion Function in Human Decidual Natural Killer Cells,” Bioengineering (Basel) 10, no. 9 (2023): 1008.

[109] H. D. Kopcow, D. S. J. Allan, X. Chen, et al., “Human Decidual NK Cells Form Immature Activating Synapses and Are Not Cytotoxic,” Proceedings of the National Academy of Sciences of the United States of America 102, no. 43 (2005): 15563-15568.

[110] D. Feyaerts, M. Benner, G. Comitini, et al., “NK Cell Receptor Profiling of Endometrial and Decidual NK Cells Reveals Pregnancy-Induced Adaptations,” Frontiers in Immunology 15 (2024): 1353556.

[111] J. Kieckbusch, L. M. Gaynor, A. Moffett, and F. Colucci, “Corrigendum: MHC-Dependent Inhibition of Uterine NK Cells Impedes Fetal Growth and Decidual Vascular Remodeling,” Nature Communications 8 (2017): 15444.

[112] D. M. Depierreux, J. Kieckbusch, N. Shreeve, et al., “Beyond Maternal Tolerance: Education of Uterine Natural Killer Cells by Maternal MHC Drives Fetal Growth,” Frontiers in Immunology 13 (2022): 808227.

[113] A. M. Sharkey, L. Gardner, S. Hiby, et al., “Killer Ig-Like Receptor Expression in Uterine NK Cells Is Biased Toward Recognition of HLA-C and Alters With Gestational Age,” Journal of Immunology 181, no. 1 (2008): 39-46.

[114] S. E. Hiby, R. Apps, A. M. Sharkey, et al., “Maternal Activating KIRs Protect Against Human Reproductive Failure Mediated by Fetal HLA-C2,” Journal of Clinical Investigation 120, no. 11 (2010): 4102-4110.

[115] E. M. Whettlock, E. V. Woon, A. O. Cuff, B. Browne, M. R. Johnson, and V. Male, “Dynamic Changes in Uterine NK Cell Subset Frequency and Function Over the Menstrual Cycle and Pregnancy,” Frontiers in Immunology 13 (2022): 880438.

[116] A. Moffett, O. Chazara, F. Colucci, and M. H. Johnson, “Variation of Maternal KIR and Fetal HLA-C Genes in Reproductive Failure: Too Early for Clinical Intervention,” Reproductive Biomedicine Online 33, no. 6 (2016): 763-769.

[117] S. Xiong, A. M. Sharkey, P. R. Kennedy, et al., “Maternal Uterine NK Cell-Activating Receptor KIR2DS1 Enhances Placentation,” Journal of Clinical Investigation 123, no. 10 (2013): 4264-4272.

[118] P. R. Kennedy, O. Chazara, L. Gardner, et al., “Activating KIR2DS4 Is Expressed by Uterine NK Cells and Contributes to Successful Pregnancy,” Journal of Immunology 197, no. 11 (2016): 4292-4300.

[119] X. Yang, E. Yang, W.-J. Wang, et al., “Decreased HLA-C1 Alleles in Couples of KIR2DL2 Positive Women With Recurrent Pregnancy Loss,” Journal of Reproductive Immunology 142 (2020): 103186.

[120] M. A. Ivarsson, L. Loh, N. Marquardt, et al., “Differentiation and Functional Regulation of Human Fetal NK Cells,” Journal of Clinical Investigation 123, no. 9 (2013): 3889-3901.

[121] R. Apps, A. Sharkey, L. Gardner, et al., “Genome-Wide Expression Profile of First Trimester Villous and Extravillous Human Trophoblast Cells,” Placenta 32, no. 1 (2011): 33-43.

[122] P. Vacca, G. Pietra, M. Falco, et al., “Analysis of Natural Killer Cells Isolated From Human Decidua: Evidence That 2B4 (CD244) Functions as an Inhibitory Receptor and Blocks NK-Cell Function,” Blood 108, no. 13 (2006): 4078-4085.

[123] L. Leon, A. M. Felker, V. R. Kay, M. M. Tu, A. P. Makrigiannis, and B. A. Croy, “Ly49 Knockdown in Mice Results in Aberrant Uterine Crypt Formation and Impaired Blastocyst Implantation,” Placenta 39 (2016): 147-150.

[124] H. Yadi, S. Burke, Z. Madeja, M. Hemberger, A. Moffett, and F. Colucci, “Unique Receptor Repertoire in Mouse Uterine NK Cells,” Journal of Immunology 181, no. 9 (2008): 6140-6147.

[125] L. M. Gaynor and F. Colucci, “Uterine Natural Killer Cells: Functional Distinctions and Influence on Pregnancy in Humans and Mice,” Frontiers in Immunology 8 (2017): 467.

[126] T. Komatsu, I. Konishi, M. Mandai, T. Mori, H. Hiai, and M. Fukumoto, “Expression of Class I Human Leukocyte Antigen (HLA) and beta2-Microglobulin Is Associated With Decidualization of Human Endometrial Stromal Cells,” Human Reproduction 13, no. 8 (1998): 2246-2251.

[127] I. Nowak, A. Malinowski, H. Tchórzewski, et al., “HLA-C C1C2 Heterozygosity May Protect Women Bearing the Killer Immunoglobulin-Like Receptor AA Genotype From Spontaneous Abortion,” Journal of Reproductive Immunology 88, no. 1 (2011): 32-37.

[128] A. Braunschweig, T. G. Poehlmann, S. Busch, E. Schleussner, and U. R. Markert, “Signal Transducer and Activator of Transcription 3 (STAT3) and Suppressor of Cytokine Signaling (SOCS3) Balance Controls Cytotoxicity and IL-10 Expression in Decidual-Like Natural Killer Cell Line NK-92,” American Journal of Reproductive Immunology 66, no. 4 (2011): 329-335.

[129] P. Le Bouteiller, “HLA-G in Human Early Pregnancy: Control of Uterine Immune Cell Activation and Likely Vascular Remodeling,” Biomedical Journal 38, no. 1 (2015): 32-38.

[130] S. Rajagopalan and E. O. Long, “Cellular Senescence Induced by CD158d Reprograms Natural Killer Cells to Promote Vascular Remodeling,” Proceedings of the National Academy of Sciences of the United States of America 109, no. 50 (2012): 20596-20601.

[131] T. Tilburgs, J. H. Evans, Â. C. Crespo, and J. L. Strominger, “The HLA-G Cycle Provides for Both NK Tolerance and Immunity at the Maternal-Fetal Interface,” Proceedings of the National Academy of Sciences of the United States of America 112, no. 43 (2015): 13312-13317.

[132] D. J. Schust, A. B. Hill, and H. L. Ploegh, “Herpes Simplex Virus Blocks Intracellular Transport of HLA-G in Placentally Derived Human Cells,” Journal of Immunology 157, no. 8 (1996): 3375-3380.

[133] W.-T. Hu, L.-L. Huang, M.-Q. Li, L.-P. Jin, D.-J. Li, and X.-Y. Zhu, “Decidual Stromal Cell-Derived IL-33 Contributes to Th2 Bias and Inhibits Decidual NK Cell Cytotoxicity Through NF-κB Signaling in Human Early Pregnancy,” Journal of Reproductive Immunology 109 (2015): 52-65.

[134] S. Mani, J. Garifallou, S.-J. Kim, et al., “Uterine Macrophages and NK Cells Exhibit Population and Gene-Level Changes After Implantation but Maintain Pro-Invasive Properties,” Frontiers in Immunology 15 (2024): 1364036, https://doi.org/10.3389/fimmu.2024.1364036.

[135] V. Mikhailova, P. Grebenkina, E. Khokhlova, et al., “Pro- and Anti-Inflammatory Cytokines in the Context of NK Cell-Trophoblast Interactions,” International Journal of Molecular Sciences 23, no. 4 (2022): 2387.

[136] R. Bender Atik, O. B. Christiansen, J. Elson, et al., “ESHRE Guideline: Recurrent Pregnancy Loss,” Human Reproduction Open 2018, no. 2 (2018): hoy004.

[137] D. Cimadomo, L. Craciunas, N. Vermeulen, K. Vomstein, and B. Toth, “Definition, Diagnostic and Therapeutic Options in Recurrent Implantation Failure: An International Survey of Clinicians and Embryologists,” Human Reproduction 36, no. 2 (2021): 305-317.

[138] M. Ou, L. Luo, Y. Yang, et al., “Decrease in Peripheral Natural Killer Cell Level During Early Pregnancy Predicts Live Birth Among Women With Unexplained Recurrent Pregnancy Loss: A Prospective Cohort Study,” American Journal of Obstetrics and Gynecology 230, no. 6 (2024): e1-e13.

[139] M. Ghafourian, N. Karami, A. Khodadadi, and R. Nikbakht, “Increase of CD69, CD161 and CD94 on NK Cells in Women With Recurrent Spontaneous Abortion and In Vitro Fertilization Failure,” Iranian Journal of Immunology 11, no. 2 (2014): 84-96.

[140] N. Karami, M. G. Boroujerdnia, R. Nikbakht, and A. Khodadadi, “Enhancement of Peripheral Blood CD56(Dim) Cell and NK Cell Cytotoxicity in Women With Recurrent Spontaneous Abortion or In Vitro Fertilization Failure,” Journal of Reproductive Immunology 95, no. 1-2 (2012): 87-92.

[141] V. P. Chernyshov, B. V. Dons'koi, I. O. Sudoma, and Y. O. Goncharova, “Multiple Immune Deviations Predictive for IVF Failure as Possible Markers for IVIG Therapy,” Immunology Letters 176 (2016): 44-50.

[142] C. B. Coulam and R. G. Roussev, “Correlation of NK Cell Activation and Inhibition Markers With NK Cytoxicity Among Women Experiencing Immunologic Implantation Failure After In Vitro Fertilization and Embryo Transfer,” Journal of Assisted Reproduction and Genetics 20, no. 2 (2003): 58-62.

[143] O. El-Badawy, A. S. Helmy, A. M. Abbas, A. M. Zahran, N. A. Afifi, and M. H. Abdel-Rahim, “Concordance Between Peripheral and Decidual NK Cell Subsets and Killer Immunoglobulin-Like Receptors in Women With Recurrent Spontaneous Miscarriages,” Journal of Reproductive Immunology 140 (2020): 103130.

[144] Y. Zhang, A. Zhao, X. Wang, G. Shi, H. Jin, and Q. Lin, “Expressions of Natural Cytotoxicity Receptors and NKG2D on Decidual Natural Killer Cells in Patients Having Spontaneous Abortions,” Fertility and Sterility 90, no. 5 (2008): 1931-1937.

[145] A. Fukui, E. Ntrivalas, A. Gilman-Sachs, et al., “Expression of Natural Cytotoxicity Receptors and a2V-ATPase on Peripheral Blood NK Cell Subsets in Women With Recurrent Spontaneous Abortions and Implantation Failures,” American Journal of Reproductive Immunology 56, no. 5-6 (2006): 312-320.

[146] D. S. J. Allan, B. Rybalov, G. Awong, et al., “TGF-β Affects Development and Differentiation of Human Natural Killer Cell Subsets,” European Journal of Immunology 40, no. 8 (2010): 2289-2295.

[147] Y. Hou, Q. Liu, D. Jin, J. Li, L. Huang, and C. Qiao, “The Predictive Value of NKG2C+NK Cells and LILRB1+NK Cells in Recurrent Spontaneous Abortion,” American Journal of Reproductive Immunology 89, no. 6 (2023): e13627.

[148] M. Du, Y. Li, H. Gu, et al., “Assessment of the Risk of Unexplained Recurrent Spontaneous Abortion Based on the Proportion and Correlation of NK Cells and T Cells in Peripheral Blood,” Technology and Health Care 31, no. S1 (2023): 97-109.

[149] J. Sun, M. Yang, Y. Ban, et al., “Tim-3 Is Upregulated in NK Cells During Early Pregnancy and Inhibits NK Cytotoxicity Toward Trophoblast in Galectin-9 Dependent Pathway,” PLoS One 11, no. 1 (2016): e0147186.

[150] Y.-H. Li, W.-H. Zhou, Y. Tao, et al., “The Galectin-9/Tim-3 Pathway Is Involved in the Regulation of NK Cell Function at the Maternal-Fetal Interface in Early Pregnancy,” Cellular & Molecular Immunology 13, no. 1 (2016): 73-81.

[151] D. A. Clark, G. Vince, K. C. Flanders, H. Hirte, and P. Starkey, “CD56+ Lymphoid Cells in Human First Trimester Pregnancy Decidua as a Source of Novel Transforming Growth Factor-Beta 2-Related Immunosuppressive Factors,” Human Reproduction 9, no. 12 (1994): 2270-2277.

[152] Y. Li, J. Zhang, D. Zhang, et al., “Tim-3 Signaling in Peripheral NK Cells Promotes Maternal-Fetal Immune Tolerance and Alleviates Pregnancy Loss,” Science Signaling 10, no. 498 (2017): eaah4323.

[153] S. Tripathi, L. Chabtini, P. J. Dakle, et al., “Effect of TIM-3 Blockade on the Immunophenotype and Cytokine Profile of Murine Uterine NK Cells,” PLoS One 10, no. 4 (2015): e0123439.

[154] J. O. Kim, W. S. Lee, B. E. Lee, et al., “Interleukin-1 Beta -511T>C Genetic Variant Contributes to Recurrent Pregnancy Loss Risk and Peripheral Natural Killer Cell Proportion,” Fertility and Sterility 102, no. 1 (2014): 206-212.

[155] H. Hadinedoushan, M. Mirahmadian, and A. Aflatounian, “Increased Natural Killer Cell Cytotoxicity and IL-2 Production in Recurrent Spontaneous Abortion,” American Journal of Reproductive Immunology 58, no. 5 (2007): 409-414.

[156] Y. Zhang, C. Huang, R. Lian, et al., “The Low Cytotoxic Activity of Peripheral Blood NK Cells May Relate to Unexplained Recurrent Miscarriage,” American Journal of Reproductive Immunology 85, no. 6 (2021): e13388.

[157] S. Hosseini, A.-H. Zarnani, H. Asgarian-Omran, et al., “Comparative Analysis of NK Cell Subsets in Menstrual and Peripheral Blood of Patients With Unexplained Recurrent Spontaneous Abortion and Fertile Subjects,” Journal of Reproductive Immunology 103 (2014): 9-17, https://doi.org/10.1016/j.jri.2014.03.002.

[158] X. Tong, M. Gao, X. Du, et al., “Analysis of Uterine CD49a+ NK Cell Subsets in Menstrual Blood Reflects Endometrial Status and Association With Recurrent Spontaneous Abortion,” Cellular & Molecular Immunology 18, no. 7 (2021): 1838-1840.

[159] K. Vomstein, P. Egerup, A. M. Kolte, et al., “Biopsy-Free Profiling of the Uterine Immune System in Patients With Recurrent Pregnancy Loss and Unexplained Infertility,” Reproductive Biomedicine Online 47, no. 2 (2023): 103207.

[160] B. Fu, Y. Zhou, X. Ni, et al., “Natural Killer Cells Promote Fetal Development Through the Secretion of Growth-Promoting Factors,” Immunity 47, no. 6 (2017): 1100-1113.

[161] X. Du, H. Zhu, D. Jiao, et al., “Human-Induced CD49a+ NK Cells Promote Fetal Growth,” Frontiers in Immunology 13 (2022): 821542, https://doi.org/10.3389/fimmu.2022.821542.

[162] S. M. Gordon, J. Chaix, L. J. Rupp, et al., “The Transcription Factors T-Bet and Eomes Control Key Checkpoints of Natural Killer Cell Maturation,” Immunity 36, no. 1 (2012): 55-67.

[163] J. Zhang, S. Le Gras, K. Pouxvielh, et al., “Sequential Actions of EOMES and T-BET Promote Stepwise Maturation of Natural Killer Cells,” Nature Communications 12, no. 1 (2021): 5446.

[164] C. Daussy, F. Faure, K. Mayol, et al., “T-Bet and Eomes Instruct the Development of Two Distinct Natural Killer Cell Lineages in the Liver and in the Bone Marrow,” Journal of Experimental Medicine 211, no. 3 (2014): 563-577.

[165] Q. Fu, Y. Sun, Y. Tao, et al., “Involvement of the JAK-STAT Pathway in Collagen Regulation of Decidual NK Cells,” American Journal of Reproductive Immunology 78, no. 6 (2017): e12769, https://doi.org/10.1111/aji.12769.

[166] C. Tayade, Y. Fang, G. P. Black, V. A. P, A. Erlebacher, and B. A. Croy, “Differential Transcription of Eomes and T-Bet During Maturation of Mouse Uterine Natural Killer Cells,” Journal of Leukocyte Biology 78, no. 6 (2005): 1347-1355, https://doi.org/10.1189/jlb.0305142.

[167] C. Seillet, N. D. Huntington, P. Gangatirkar, et al., “Differential Requirement for Nfil3 During NK Cell Development,” Journal of Immunology 192, no. 6 (2014): 2667-2676.

[168] V. Male, I. Nisoli, T. Kostrzewski, et al., “The Transcription Factor E4bp4/Nfil3 Controls Commitment to the NK Lineage and Directly Regulates Eomes and Id2 Expression,” Journal of Experimental Medicine 211, no. 4 (2014): 635-642.

[169] Y. C. Guterstam, G. Acharya, K. Schott, N. K. Björkström, S. Gidlöf, and M. A. Ivarsson, “Immune Cell Profiling of Vaginal Blood From Patients With Early Pregnancy Bleeding,” American Journal of Reproductive Immunology 90, no. 2 (2023): e13738.

[170] L. Kiekens, W. Van Loocke, S. Taveirne, et al., “T-BET and EOMES Accelerate and Enhance Functional Differentiation of Human Natural Killer Cells,” Frontiers in Immunology 12 (2021): 732511.

[171] O. Pikovskaya, J. Chaix, N. J. Rothman, et al., “Cutting Edge: Eomesodermin Is Sufficient to Direct Type 1 Innate Lymphocyte Development Into the Conventional NK Lineage,” Journal of Immunology 196, no. 4 (2016): 1449-1454, https://doi.org/10.4049/jimmunol.1502396.

[172] F. Wang, W. Jia, M. Fan, et al., “Single-Cell Immune Landscape of Human Recurrent Miscarriage,” Genomics, Proteomics & Bioinformatics 19, no. 2 (2021): 208-222.

[173] C. Guo, P. Cai, L. Jin, et al., “Single-Cell Profiling of the Human Decidual Immune Microenvironment in Patients With Recurrent Pregnancy Loss,” Cell Discovery 7, no. 1 (2021): 1.

[174] Y. Yang, J. Qiu, Q. Xu, et al., “The Loss of dNK1/2 and EVT1 Cells at the Maternal-Fetal Interface Is Associated With Recurrent Miscarriage,” Biology of Reproduction 112, no. 1 (2024): 119-129, https://doi.org/10.1093/biolre/ioae136.

[175] A.-S. Braun, K. Vomstein, E. Reiser, et al., “NK and T Cell Subtypes in the Endometrium of Patients With Recurrent Pregnancy Loss and Recurrent Implantation Failure: Implications for Pregnancy Success,” Journal of Clinical Medicine 12, no. 17 (2023): 5585.

[176] I. Cuadrado-Torroglosa, A. Pacheco, A. Barrio, et al., “Increased Cytotoxic Natural Killer Cells in the Endometrium Alone Cannot Be Considered the Immunological Cause of Recurrent Miscarriage,” Fertility and Sterility 120, no. 1 (2023): 101-110.

[177] D. W. Park, H. J. Lee, C. W. Park, S. R. Hong, J. Kwak-Kim, and K. M. Yang, “Peripheral Blood NK Cells Reflect Changes in Decidual NK Cells in Women With Recurrent Miscarriages,” American Journal of Reproductive Immunology 63, no. 2 (2010): 173-180.

[178] D. Qin, H. Xu, Z. Chen, et al., “The Peripheral and Decidual Immune Cell Profiles in Women With Recurrent Pregnancy Loss,” Frontiers in Immunology 13 (2022): 994240.

[179] K. Fuchinoue, A. Fukui, H. Chiba, et al., “Expression of Retinoid-Related Orphan Receptor (ROR)γt on NK22 Cells in the Peripheral Blood and Uterine Endometrium of Women With Unexplained Recurrent Pregnancy Loss and Unexplained Infertility,” Journal of Obstetrics and Gynaecology Research 42, no. 11 (2016): 1541-1552.

[180] M. Yamamoto, A. Fukui, C. Mai, et al., “Evaluation of NKp46 Expression and Cytokine Production of Decidual NK Cells in Women With Recurrent Pregnancy Loss,” Reproductive Medicine and Biology 21, no. 1 (2022): e12478.

[181] S. Bao, Z. Chen, D. Qin, et al., “Single-Cell Profiling Reveals Mechanisms of Uncontrolled Inflammation and Glycolysis in Decidual Stromal Cell Subtypes in Recurrent Miscarriage,” Human Reproduction 38, no. 1 (2023): 57-74.

[182] F. Kara, O. Cinar, E. Erdemli-Atabenli, B. Tavil-Sabuncuoglu, and A. Can, “Ultrastructural Alterations in Human Decidua in Miscarriages Compared to Normal Pregnancy Decidua,” Acta Obstetricia et Gynecologica Scandinavica 86, no. 9 (2007): 1079-1086.

[183] S. V. Dambaeva, D. H. Lee, N. Sung, et al., “Recurrent Pregnancy Loss in Women With Killer Cell Immunoglobulin-Like Receptor KIR2DS1 Is Associated With an Increased HLA-C2 Allelic Frequency,” American Journal of Reproductive Immunology 75, no. 2 (2016): 94-103.

[184] M. Bora, S. Singha, T. Madan, G. Deka, S. G. Hazarika, and S. Baruah, “HLA-G Isoforms, HLA-C Allotype and Their Expressions Differ Between Early Abortus and Placenta in Relation to Spontaneous Abortions,” Placenta 149 (2024): 44-53.

[185] R. M. Faridi, V. Das, G. Tripthi, S. Talwar, F. Parveen, and S. Agrawal, “Influence of Activating and Inhibitory Killer Immunoglobulin-Like Receptors on Predisposition to Recurrent Miscarriages,” Human Reproduction 24, no. 7 (2009): 1758-1764.

[186] C. Mai, A. Fukui, R. Takeyama, et al., “NK Cells That Differ in Expression of NKp46 Might Play Different Roles in Endometrium,” Journal of Reproductive Immunology 147 (2021): 103367.

[187] S.-L. Yang, H.-X. Tan, T.-T. Niu, D.-J. Li, H.-Y. Wang, and M.-Q. Li, “Kynurenine Promotes the Cytotoxicity of NK Cells Through Aryl Hydrocarbon Receptor in Early Pregnancy,” Journal of Reproductive Immunology 143 (2021): 103270.

[188] S. P. Murphy, L. D. Fast, N. N. Hanna, and S. Sharma, “Uterine NK Cells Mediate Inflammation-Induced Fetal Demise in IL-10-Null Mice,” Journal of Immunology 175, no. 6 (2005): 4084-4090.

[189] S. M. Blois, N. Freitag, I. Tirado-González, et al., “NK Cell-Derived IL-10 Is Critical for DC-NK Cell Dialogue at the Maternal-Fetal Interface,” Scientific Reports 7, no. 1 (2017): 2189.

[190] J. Peng, D. Monsivais, R. You, H. Zhong, S. A. Pangas, and M. M. Matzuk, “Uterine Activin Receptor-Like Kinase 5 Is Crucial for Blastocyst Implantation and Placental Development,” Proceedings of the National Academy of Sciences of the United States of America 112, no. 36 (2015): E5098-E5107.

[191] B. M. Fonseca, S. C. Cunha, D. Gonçalves, et al., “Decidual NK Cell-Derived Conditioned Medium From Miscarriages Affects Endometrial Stromal Cell Decidualisation: Endocannabinoid Anandamide and Tumour Necrosis Factor-α Crosstalk,” Human Reproduction 35, no. 2 (2020): 265-274.

[192] A. Erlebacher, D. Zhang, A. F. Parlow, and L. H. Glimcher, “Ovarian Insufficiency and Early Pregnancy Loss Induced by Activation of the Innate Immune System,” Journal of Clinical Investigation 114, no. 1 (2004): 39-48.

[193] S. Verma, R. Pal, and S. K. Gupta, “Decrease in Invasion of HTR-8/SVneo Trophoblastic Cells by Interferon Gamma Involves Cross-Communication of STAT1 and BATF2 That Regulates the Expression of JUN,” Cell Adhesion & Migration 12, no. 5 (2018): 432-446.

[194] Z.-Y. Li, Z.-H. Song, C.-Y. Meng, D.-D. Yang, Y. Yang, and J.-P. Peng, “IFN-γ Modulates Ly-49 Receptors on NK Cells in IFN-γ-Induced Pregnancy Failure,” Scientific Reports 5 (2015): 18159.

[195] K. Kusakabe, M. Naka, Y. Ito, N. Eid, and Y. Otsuki, “Regulation of Natural-Killer Cell Cytotoxicity and Enhancement of Complement Factors in the Spontaneously Aborted Mouse Placenta,” Fertility and Sterility 90, no. 4 (2008): 1451-1459.

[196] A. Nakashima, A. Shiozaki, S. Myojo, et al., “Granulysin Produced by Uterine Natural Killer Cells Induces Apoptosis of Extravillous Trophoblasts in Spontaneous Abortion,” American Journal of Pathology 173, no. 3 (2008): 653-664.

[197] N. Sotnikova, D. Voronin, Y. Antsiferova, and E. Bukina, “Interaction of Decidual CD56+ NK With Trophoblast Cells During Normal Pregnancy and Recurrent Spontaneous Abortion at Early Term of Gestation,” Scandinavian Journal of Immunology 80, no. 3 (2014): 198-208.

[198] G. Yin, C. Li, B. Shan, et al., “Insufficient Peroxiredoxin-2 Expression in Uterine NK Cells Obtained From a Murine Model of Abortion,” Journal of Cellular Biochemistry 112, no. 3 (2011): 773-781.

[199] J. Zheng, Y. Li, Y. Sang, et al., “Pigment Epithelium-Derived Factor, a Novel Decidual Natural Killer Cells-Derived Factor, Protects Decidual Stromal Cells via Anti-Inflammation and Anti-Apoptosis in Early Pregnancy,” Human Reproduction 35, no. 7 (2020): 1537-1552.

[200] Y. Zhou, B. Fu, X. Xu, et al., “PBX1 Expression in Uterine Natural Killer Cells Drives Fetal Growth,” Science Translational Medicine 12, no. 537 (2020): eaax1798.

[201] H. Lu, H.-L. Yang, W.-J. Zhou, et al., “Rapamycin Prevents Spontaneous Abortion by Triggering Decidual Stromal Cell Autophagy-Mediated NK Cell Residence,” Autophagy 17, no. 9 (2021): 2511-2527.

[202] H.-X. Tan, S.-L. Yang, M.-Q. Li, and H.-Y. Wang, “Autophagy Suppression of Trophoblast Cells Induces Pregnancy Loss by Activating Decidual NK Cytotoxicity and Inhibiting Trophoblast Invasion,” Cell Communication and Signaling: CCS 18, no. 1 (2020): 73.

[203] I. Yougbaré, W.-S. Tai, D. Zdravic, et al., “Activated NK Cells Cause Placental Dysfunction and Miscarriages in Fetal Alloimmune Thrombocytopenia,” Nature Communications 8, no. 1 (2017): 224.

[204] N. Liu, H. Shen, Z. Wang, X. Qin, M. Li, and X. Zhang, “Autophagy Inhibition in Trophoblasts Induces Aberrant Shift in CXCR4+ Decidual NK Cell Phenotype Leading to Pregnancy Loss,” Journal of Clinical Medicine 12, no. 23 (2023): 7491.

[205] F. Lyu, C. Burzynski, Y. Y. Fang, et al., “Maternal CXCR4 Deletion Results in Placental Defects and Pregnancy Loss Mediated by Immune Dysregulation,” JCI Insight 8, no. 21 (2023): e172216.

[206] S. S. Shobeiri, Z. Rahmani, H. Hossein Nataj, H. Ranjbaran, M. Mohammadi, and S. Abediankenari, “Uterine Natural Killer Cell and Human Leukocyte Antigen-G1 and Human Leukocyte Antigen-G5 Expression in Vaginal Discharge of Threatened-Abortion Women: A Case-Control Study,” Journal of Immunology Research 2015 (2015): 692198.

[207] S. Saito, T. Morii, M. Enomoto, et al., “The Effect of Interleukin 2 and Transforming Growth Factor-Beta 2 (TGF-Beta 2) on the Proliferation and Natural Killer Activity of Decidual CD16- CD56bright Natural Killer Cells,” Cellular Immunology 152, no. 2 (1993): 605-613.

[208] T. G. Poehlmann, A. Schaumann, S. Busch, et al., “Inhibition of Term Decidual NK Cell Cytotoxicity by Soluble HLA-G1,” American Journal of Reproductive Immunology 56, no. 5-6 (2006): 275-285.

[209] S. Wang, X. Zhou, and J. Yang, “Integrin αvβ3 Is Essential for Maintenance of Decidua Tissue Homeostasis and of Natural Killer Cell Immune Tolerance During Pregnancy,” Reproductive Sciences 25, no. 9 (2018): 1424-1430.

[210] R. Hadas, E. Gershon, A. Cohen, et al., “Hyaluronan Control of the Primary Vascular Barrier During Early Mouse Pregnancy Is Mediated by Uterine NK Cells,” JCI Insight 5, no. 22 (2020): e135775.

[211] D. Zhang, Y. Yu, C. Ding, R. Zhang, T. Duan, and Q. Zhou, “Decreased B7-H3 Promotes Unexplained Recurrent Miscarriage via RhoA/ROCK2 Signaling Pathway and Regulates the Secretion of Decidual NK Cells†,” Biology of Reproduction 108, no. 3 (2023): 504-518.

[212] M. Ono, N. Toyoda, K. Kagami, et al., “Uterine Deletion of Bmal1 Impairs Placental Vascularization and Induces Intrauterine Fetal Death in Mice,” International Journal of Molecular Sciences 23, no. 14 (2022): 7637, https://doi.org/10.3390/ijms23147637.

[213] J. Zhang, M. Xue, J. Huang, et al., “Deficiency of UCHL1 Results in Insufficient Decidualization Accompanied by Impaired dNK Modulation and Eventually Miscarriage,” Journal of Translational Medicine 22, no. 1 (2024): 478.

[214] J.-W. Shi, Z.-Z. Lai, H.-L. Yang, et al., “An IGF1-Expressing Endometrial Stromal Cell Population Is Associated With Human Decidualization,” BMC Biology 20, no. 1 (2022): 276.

[215] X. Zhu, M. Du, H. Gu, et al., “Integrated Analysis of lncRNA and mRNA Expression Profiles in Patients With Unexplained Recurrent Spontaneous Abortion,” American Journal of Reproductive Immunology 89, no. 6 (2023): e13691.

[216] D. Tiwari, P. D. Bose, R. Sultana, C. R. Das, and S. Bose, “Preterm Delivery and Associated Negative Pregnancy Outcome—A Tale of Faulty Progesterone Receptor Signalling Pathway and Linked Derailed Immunomodulation: A Study From Northeast India,” Journal of Reproductive Immunology 118 (2016): 76-84.

[217] K. Kitaya, J. Yasuda, I. Yagi, Y. Tada, S. Fushiki, and H. Honjo, “IL-15 Expression at Human Endometrium and Decidua,” Biology of Reproduction 63, no. 3 (2000): 683-687.

[218] J. Chen, Y. Li, L. Xu, Y. Sang, D. Li, and M. Du, “Paradoxical Expression of NRP1 in Decidual Stromal and Immune Cells Reveals a Novel Inflammation Balancing Mechanism During Early Pregnancy,” Inflammation Research 72, no. 7 (2023): 1341-1357.

[219] G. Sacks, Y. Yang, E. Gowen, S. Smith, L. Fay, and M. Chapman, “Detailed Analysis of Peripheral Blood Natural Killer Cells in Women With Repeated IVF Failure,” American Journal of Reproductive Immunology 67, no. 5 (2012): 434-442.

[220] M. G. Matteo, P. Greco, P. Rosenberg, et al., “Normal Percentage of CD56bright Natural Killer Cells in Young Patients With a History of Repeated Unexplained Implantation Failure After In Vitro Fertilization Cycles,” Fertility and Sterility 88, no. 4 (2007): 990-993.

[221] E. Miko, Z. Manfai, M. Meggyes, et al., “Possible Role of Natural Killer and Natural Killer T-Like Cells in Implantation Failure After IVF,” Reproductive Biomedicine Online 21, no. 6 (2010): 750-756.

[222] M. Y. Thum, S. Bhaskaran, A. S. Bansal, et al., “Simple Enumerations of Peripheral Blood Natural Killer (CD56+ NK) Cells, B Cells and T Cells Have no Predictive Value in IVF Treatment Outcome,” Human Reproduction 20, no. 5 (2005): 1272-1276.

[223] H. Zhang, C. Huang, X. Chen, et al., “The Number and Cytotoxicity and the Expression of Cytotoxicity-Related Molecules in Peripheral Natural Killer (NK) Cells Do Not Predict the Repeated Implantation Failure (RIF) for the In Vitro Fertilization Patients,” Genes & Diseases 7, no. 2 (2020): 283-289.

[224] B. V. Dons'koi, “Accentuated Hypo- and Hyper-NK Lymphocyte CD8 Expression Is a Marker of NK Subsets' Misbalance and Is Predictive for Reproductive Failures,” Immunobiology 220, no. 5 (2015): 649-655.

[225] M.-Y. Thum, H. I. Abdalla, S. Bhaskaran, et al., “The Relationship of Systemic TNF-Alpha and IFN-Gamma With IVF Treatment Outcome and Peripheral Blood NK Cells,” American Journal of Reproductive Immunology 57, no. 3 (2007): 210-217.

[226] T. Zhang, W. Zhu, Y. Zhao, et al., “Early Transient Suppression of Immune Checkpoint Proteins T-Cell Immunoglobulin Mucin-3 and Programmed Cell Death-1 in Peripheral Blood Lymphocytes After Blastocyst Transfer Is Associated With Successful Implantation,” Fertility and Sterility 114, no. 2 (2020): 426-435.

[227] C. Huang, Y. Zhang, Z. Xiang, et al., “Granzyme B-Expressing γδ-T and NK Cells as a Predictor of Clinical Pregnancy Failure in Patients With Unexplained Repeated Implantation Failure,” Journal of Reproductive Immunology 144 (2021): 103269, https://doi.org/10.1016/j.jri.2020.103269.

[228] A. Fukui, J. Kwak-Kim, E. Ntrivalas, A. Gilman-Sachs, S.-K. Lee, and K. Beaman, “Intracellular Cytokine Expression of Peripheral Blood Natural Killer Cell Subsets in Women With Recurrent Spontaneous Abortions and Implantation Failures,” Fertility and Sterility 89, no. 1 (2008): 157-165.

[229] Y. J. Hur, E. J. Yu, S.-A. Choe, J. Paek, and Y. S. Kim, “Peripheral Blood Natural Killer Cell Proportion and Ovarian Function in Women With Recurrent Implantation Failure,” Gynecological Endocrinology 36, no. 10 (2020): 922-925.

[230] B. Dons'koi, O. Onyshchuk, I. Kononenko, et al., “Accentuated Peripheral Blood NK Cytotoxicity Forms an Unfavorable Background for Embryo Implantation and Gestation,” Diagnostics (Basel) 12, no. 4 (2022): 908, https://doi.org/10.3390/diagnostics12040908.

[231] X. Fan, Q. Zhao, Y. Li, et al., “Immune Profiling and RNA-Seq Uncover the Cause of Partial Unexplained Recurrent Implantation Failure,” International Immunopharmacology 121 (2023): 110513, https://doi.org/10.1016/j.intimp.2023.110513.

[232] R. Jiang, G. Yan, J. Xing, et al., “Abnormal Ratio of CD57+ Cells to CD56+ Cells in Women With Recurrent Implantation Failure,” American Journal of Reproductive Immunology 78, no. 5 (2017): e12708.

[233] E. V. Woon, D. Nikolaou, K. MacLaran, et al., “Uterine NK Cells Underexpress KIR2DL1/S1 and LILRB1 in Reproductive Failure,” Frontiers in Immunology 13 (2022): 1108163.

[234] R. Gil Laborda, E. R. de Frías, N. Subhi-Issa, et al., “Centromeric AA Motif in KIR as an Optimal Surrogate Marker for Precision Definition of Alloimmune Reproductive Failure,” Scientific Reports 14, no. 1 (2024): 3354.

[235] H. Papúchová, M. H. Saxtorph, T. Hallager, et al., “Endometrial HLA-F Expression Is Influenced by Genotypes and Correlates Differently With Immune Cell Infiltration in IVF and Recurrent Implantation Failure Patients,” Human Reproduction 37, no. 8 (2022): 1816-1834.

[236] N. K. Binder, J. Evans, D. K. Gardner, L. A. Salamonsen, and N. J. Hannan, “Endometrial Signals Improve Embryo Outcome: Functional Role of Vascular Endothelial Growth Factor Isoforms on Embryo Development and Implantation in Mice,” Human Reproduction 29, no. 10 (2014): 2278-2286.

[237] G. Junovich, A. Azpiroz, E. Incera, C. Ferrer, A. Pasqualini, and G. Gutierrez, “Endometrial CD16(+) and CD16(−) NK Cell Count in Fertility and Unexplained Infertility,” American Journal of Reproductive Immunology 70, no. 3 (2013): 182-189.

[238] Z.-Z. Lai, Y. Wang, W.-J. Zhou, et al., “Single-Cell Transcriptome Profiling of the Human Endometrium of Patients With Recurrent Implantation Failure,” Theranostics 12, no. 15 (2022): 6527-6547.

[239] V. Mikhailova, E. Khokhlova, P. Grebenkina, et al., “NK-92 Cells Change Their Phenotype and Function When Cocultured With IL-15, IL-18 and Trophoblast Cells,” Immunobiology 226, no. 5 (2021): 152125.

[240] N. Lédée-Bataille, K. Bonnet-Chea, G. Hosny, S. Dubanchet, R. Frydman, and G. Chaouat, “Role of the Endometrial Tripod Interleukin-18, -15, and -12 in Inadequate Uterine Receptivity in Patients With a History of Repeated In Vitro Fertilization-Embryo Transfer Failure,” Fertility and Sterility 83, no. 3 (2005): 598-605.

[241] N. Lédée-Bataille, S. Dubanchet, A. Coulomb-L'hermine, I. Durand-Gasselin, R. Frydman, and G. Chaouat, “A New Role for Natural Killer Cells, Interleukin (IL)-12, and IL-18 in Repeated Implantation Failure After In Vitro Fertilization,” Fertility and Sterility 81, no. 1 (2004): 59-65.

[242] I. Sudoma, Y. Goncharova, B. Dons'koy, and D. Mykytenko, “Immune Phenotype of the Endometrium in Patients With Recurrent Implantation Failures After the Transfer of Genetically Tested Embryos in Assisted Reproductive Technology Programs,” Journal of Reproductive Immunology 157 (2023): 103943.

[243] A. E. Mas, M. Petitbarat, S. Dubanchet, S. Fay, N. Ledée, and G. Chaouat, “Immune Regulation at the Interface During Early Steps of Murine Implantation: Involvement of Two New Cytokines of the IL-12 Family (IL-23 and IL-27) and of TWEAK,” American Journal of Reproductive Immunology 59, no. 4 (2008): 323-338.

[244] X. Qi, M. Lei, L. Qin, M. Xie, D. Zhao, and J. Wang, “Endogenous TWEAK Is Critical for Regulating the Function of Mouse Uterine Natural Killer Cells in an Immunological Model of Pregnancy Loss,” Immunology 148, no. 1 (2016): 70-82.

[245] L. Du, W. Deng, S. Zeng, et al., “Single-Cell Transcriptome Analysis Reveals Defective Decidua Stromal Niche Attributes to Recurrent Spontaneous Abortion,” Cell Proliferation 54, no. 11 (2021): e13125.

[246] K. Wilczyńska, A. Wiśniewski, A. Malinowski, et al., “ERAP, KIR and HLA-C Gene Interaction in Susceptibility to Recurrent Spontaneous Abortion in the Polish Population,” Human Immunology 80, no. 5 (2019): 344-348.

[247] K. Piekarska, P. Radwan, A. Tarnowska, et al., “ERAP/HLA-C and KIR Genetic Profile in Couples With Recurrent Implantation Failure,” International Journal of Molecular Sciences 23, no. 20 (2022): 12518, https://doi.org/10.3390/ijms232012518.

[248] J. Kanter, S. M. Gordon, S. Mani, et al., “Hormonal Stimulation Reduces Numbers and Impairs Function of Human Uterine Natural Killer Cells During Implantation,” Human Reproduction 38, no. 6 (2023): 1047-1059.

[249] J. Cwikel, Y. Gidron, and E. Sheiner, “Psychological Interactions With Infertility Among Women,” European Journal of Obstetrics, Gynecology, and Reproductive Biology 117, no. 2 (2004): 126-131.

[250] K. Turner, M. F. Reynolds-May, E. M. Zitek, R. L. Tisdale, A. B. Carlisle, and L. M. Westphal, “Stress and Anxiety Scores in First and Repeat IVF Cycles: A Pilot Study,” PLoS One 8, no. 5 (2013): e63743.

[251] T. Wang, Y. Hou, Y. Liu, and C. Qiao, “Psychological Changes Among Women With Recurrent Pregnancy Loss During the COVID-19 Period in Northeastern China: A Cross-Sectional Study,” Frontiers in Psychology 14 (2023): 1265926.

[252] S. Hori, Y. Nakano, T. A. Furukawa, et al., “Psychosocial Factors Regulating Natural-Killer Cell Activity in Recurrent Spontaneous Abortions,” American Journal of Reproductive Immunology 44, no. 5 (2000): 299-302.

[253] W. Li, J. Newell-Price, G. L. Jones, W. L. Ledger, and T. C. Li, “Relationship Between Psychological Stress and Recurrent Miscarriage,” Reproductive Biomedicine Online 25, no. 2 (2012): 180-189.

[254] T. Hosaka, H. Matsubayashi, Y. Sugiyama, S.-i. Izumi, and T. Makino, “Effect of Psychiatric Group Intervention on Natural-Killer Cell Activity and Pregnancy Rate,” General Hospital Psychiatry 24, no. 5 (2002): 353-356.

[255] I. Hertz-Picciotto, M. Dostál, J. Dejmek, et al., “Air Pollution and Distributions of Lymphocyte Immunophenotypes in Cord and Maternal Blood at Delivery,” Epidemiology 13, no. 2 (2002): 172-183.

[256] A. M. García-Serna, T. Hernández-Caselles, P. Jiménez-Guerrero, et al., “Air Pollution From Traffic During Pregnancy Impairs Newborn's Cord Blood Immune Cells: The NELA Cohort,” Environmental Research 198 (2021): 110468.

[257] C. E. W. Herr, M. Dostal, R. Ghosh, et al., “Air Pollution Exposure During Critical Time Periods in Gestation and Alterations in Cord Blood Lymphocyte Distribution: A Cohort of Livebirths,” Environmental Health 9 (2010): 46.

[258] S. Duan, Y. Zheng, J. Tian, and L. Zhang, “Single-Cell RNA Sequencing of Estrual Mice Reveals PM2.5-Induced Uterine Cell Heterogeneity and Reproductive Toxicity,” Ecotoxicology and Environmental Safety 284 (2024): 116968.

[259] W. Zhu, Y. Gu, M. Li, et al., “Integrated Single-Cell RNA-Seq and DNA Methylation Reveal the Effects of Air Pollution in Patients With Recurrent Spontaneous Abortion,” Clinical Epigenetics 14, no. 1 (2022): 105.

[260] M. R. Ventureira, C. Sobarzo, F. Argandoña, W. A. Palomino, C. Barbeito, and E. Cebral, “Decidual Vascularization During Organogenesis After Perigestational Alcohol Ingestion,” Reproduction 158, no. 1 (2019): 109-122.

[261] F. Fischer, T. Kretschmer, P. Seifert, et al., “Single and Combined Exposures to Bisphenol A and Benzophenone-3 During Early Mouse Pregnancy Have Differential Effects on Fetal and Placental Development,” Science of the Total Environment 922 (2024): 171386.

[262] M. Sugiura-Ogasawara, Y. Ozaki, S.-i. Sonta, T. Makino, and K. Suzumori, “Exposure to Bisphenol A Is Associated With Recurrent Miscarriage,” Human Reproduction 20, no. 8 (2005): 2325-2329.

[263] G. Sher, J. D. Fisch, G. Maassarani, W. Matzner, W. Ching, and P. Chong, “Antibodies to Phosphatidylethanolamine and Phosphatidylserine Are Associated With Increased Natural Killer Cell Activity in Non-Male Factor Infertility Patients,” Human Reproduction 15, no. 9 (2000): 1932-1936.

[264] C. Perricone, C. De Carolis, R. Giacomelli, et al., “High Levels of NK Cells in the Peripheral Blood of Patients Affected With Anti-Phospholipid Syndrome and Recurrent Spontaneous Abortion: A Potential New Hypothesis,” Rheumatology (Oxford, England) 46, no. 10 (2007): 1574-1578.

[265] Y. Zhang, Y. Zhao, W. Si, et al., “Increased Peripheral NKG2A-NKG2D+CD3-CD16+CD56dim NK Cell Subset Was Positively Correlated With Antiphospholipid Antibodies in Patients of Obstetric Antiphospholipid Syndrome,” Immunological Investigations 51, no. 2 (2022): 425-437.

[266] X. Fang, F. Lu, Y. Wang, et al., “Anti-Ro/SSA and/or Anti-La/SSB Antibodies Are Associated With Adverse IVF and Pregnancy Outcomes,” Journal of Reproductive Immunology 149 (2022): 103459.

[267] G. Manukyan, E. Kriegova, L. Slavik, et al., “Antiphospholipid Antibody-Mediated NK Cell Cytotoxicity,” Journal of Reproductive Immunology 155 (2023): 103791, https://doi.org/10.1016/j.jri.2022.103791.

[268] F. Lu, Y. Wang, X. Fang, et al., “Anti-Ro/SSA and/or Anti-La/SSB Antibodies Are Associated With Adverse Endometrial Status,” American Journal of Reproductive Immunology 89, no. 6 (2023): e13630.

[269] E. Miko, M. Meggyes, K. Doba, et al., “Characteristics of Peripheral Blood NK and NKT-Like Cells in Euthyroid and Subclinical Hypothyroid Women With Thyroid Autoimmunity Experiencing Reproductive Failure,” Journal of Reproductive Immunology 124 (2017): 62-70.

[270] Y. Hidaka, N. Amino, Y. Iwatani, et al., “Increase in Peripheral Natural Killer Cell Activity in Patients With Autoimmune Thyroid Disease,” Autoimmunity 11, no. 4 (1992): 239-246.

[271] A. Chow, R. J. Baur, H. Schleusener, and J. R. Wall, “Natural Cytotoxicity of Peripheral Blood Leukocytes From Normal Subjects and Patients With Hashimoto's Thyroiditis Against Human Adult and Fetal Thyroid Cells,” Life Sciences 32, no. 1-2 (1983): 67-75.

[272] P. Triggianese, C. Perricone, P. Conigliaro, M. S. Chimenti, R. Perricone, and C. De Carolis, “Peripheral Blood Natural Killer Cells and Mild Thyroid Abnormalities in Women With Reproductive Failure,” International Journal of Immunopathology and Pharmacology 29, no. 1 (2016): 65-75.

[273] F. Zhang, W. Sun, J. Zhao, et al., “Toxoplasma Gondii Causes Adverse Pregnancy Outcomes by Damaging Uterine Tissue-Resident NK Cells That Secrete Growth-Promoting Factors,” Journal of Infectious Diseases 229, no. 2 (2024): 547-557, https://doi.org/10.1093/infdis/jiad440.

[274] X. Liu, M. Zhao, X. Yang, et al., “Toxoplasma Gondii Infection of Decidual CD1c(+) Dendritic Cells Enhances Cytotoxicity of Decidual Natural Killer Cells,” Inflammation 37, no. 4 (2014): 1261-1270.

[275] T. Fu, X. Wang, X. Zhao, et al., “Single-Cell Transcriptomic Analysis of Decidual Immune Cell Landscape in the Occurrence of Adverse Pregnancy Outcomes Induced by Toxoplasma Gondii Infection,” Parasites & Vectors 17, no. 1 (2024): 213.

[276] X. Xu, J. Zhang, S. Zhan, et al., “TGF-β1 Improving Abnormal Pregnancy Outcomes Induced by Toxoplasma Gondii Infection: Regulating NKG2D/DAP10 and Killer Subset of Decidual NK Cells,” Cellular Immunology 317 (2017): 9-17.

[277] T. Li, L. Cui, X. Xu, et al., “The Role of Tim-3 on dNK Cells Dysfunction During Abnormal Pregnancy With Toxoplasma Gondii Infection,” Frontiers in Cellular and Infection Microbiology 11 (2021): 587150.

[278] X. Wang, S. Wang, X. Xu, et al., “The Effect of Toxoplasma Gondii Infection on Galectin-9 Expression in Decidual Macrophages Contributing to Dysfunction of Decidual NK Cells During Pregnancy,” Parasites & Vectors 17, no. 1 (2024): 299.

[279] X. Xu, G. Zheng, Y. Ren, et al., “A Novel 2B4 Receptor Leads to Worse Pregnancy Outcomes by Facilitating TNF-α and IFN-γ Production in dNK Cells During Toxoplasma Gondii Infection,” Parasites & Vectors 15, no. 1 (2022): 337.

[280] M. Han, Y. Jiang, K. Lao, et al., “sHLA-G Involved in the Apoptosis of Decidual Natural Killer Cells Following Toxoplasma Gondii Infection,” Inflammation 37, no. 5 (2014): 1718-1727.

[281] J. R. Mayall, J. C. Horvat, N. E. Mangan, et al., “Interferon-Epsilon Is a Novel Regulator of NK Cell Responses in the Uterus,” EMBO Molecular Medicine 16, no. 2 (2024): 267-293, https://doi.org/10.1038/s44321-023-00018-6.

[282] M. A. B. Mercado, W. Du, P. A. Malaviarachchi, J. I. Gann, and L.-X. Li, “Innate IFN-γ Is Essential for Systemic Chlamydia muridarum Control in Mice, While CD4 T Cell-Dependent IFN-γ Production Is Highly Redundant in the Female Reproductive Tract,” Infection and Immunity 89, no. 3 (2021): e00541-20.

[283] S. Bai, G. Xu, H. Mo, et al., “Investigating Into Microbiota in the Uterine Cavity of the Unexplained Recurrent Pregnancy Loss Patients in Early Pregnancy,” Placenta 152 (2024): 1-8.

[284] R. J. Kuon, R. Togawa, K. Vomstein, et al., “Higher Prevalence of Colonization With Gardnerella Vaginalis and Gram-Negative Anaerobes in Patients With Recurrent Miscarriage and Elevated Peripheral Natural Killer Cells,” Journal of Reproductive Immunology 120 (2017): 15-19, https://doi.org/10.1016/j.jri.2017.03.001.

[285] T. Tavarna, B. Wolfe, X.-J. Wu, and L. Reyes, “Porphyromonas gingivalis-Mediated Disruption in Spiral Artery Remodeling Is Associated With Altered Uterine NK Cell Populations and Dysregulated IL-18 and Htra1,” Scientific Reports 12, no. 1 (2022): 14799.

[286] J. Wang, F. Wu, Q. Xie, et al., “Anakinra and Etanercept Prevent Embryo Loss in Pregnant Nonobese Diabetic Mice,” Reproduction 149, no. 4 (2015): 377-384, https://doi.org/10.1530/REP-14-0614.

[287] J. Zhang, R. Sun, H. Wei, D. Wu, and Z. Tian, “Toll-Like Receptor 3 Agonist Enhances IFN-Gamma and TNF-Alpha Production by Murine Uterine NK Cells,” International Immunopharmacology 7, no. 5 (2007): 588-596.

[288] M. Eriksson, S. K. Meadows, S. Basu, T. F. Mselle, C. R. Wira, and C. L. Sentman, “TLRs Mediate IFN-Gamma Production by Human Uterine NK Cells in Endometrium,” Journal of Immunology 176, no. 10 (2006): 6219-6224.

[289] A. J. Lee, N. Kandiah, K. Karimi, D. A. Clark, and A. A. Ashkar, “Interleukin-15 Is Required for Maximal Lipopolysaccharide-Induced Abortion,” Journal of Leukocyte Biology 93, no. 6 (2013): 905-912.

[290] R. Kotzur, S. Kahlon, B. Isaacson, et al., “Pregnancy Trained Decidual NK Cells Protect Pregnancies From Harmful Fusobacterium nucleatum Infection,” PLoS Pathogens 20, no. 1 (2024): e1011923.

[291] Â. C. Crespo, S. Mulik, F. Dotiwala, et al., “Decidual NK Cells Transfer Granulysin to Selectively Kill Bacteria in Trophoblasts,” Cell 182, no. 5 (2020): 1125-1139.

[292] J. Tomac, M. Mazor, B. Lisnić, et al., “Viral Infection of the Ovaries Compromises Pregnancy and Reveals Innate Immune Mechanisms Protecting Fertility,” Immunity 54, no. 7 (2021): 1478-1493.e6.

[293] J. Siewiera, H. El Costa, J. Tabiasco, et al., “Human Cytomegalovirus Infection Elicits New Decidual Natural Killer Cell Effector Functions,” PLoS Pathogens 9, no. 4 (2013): e1003257.

[294] M. Terauchi, H. Koi, C. Hayano, et al., “Placental Extravillous Cytotrophoblasts Persistently Express Class I Major Histocompatibility Complex Molecules After Human Cytomegalovirus Infection,” Journal of Virology 77, no. 15 (2003): 8187-8195.

[295] G. Markel, D. Wolf, J. Hanna, et al., “Pivotal Role of CEACAM1 Protein in the Inhibition of Activated Decidual Lymphocyte Functions,” Journal of Clinical Investigation 110, no. 7 (2002): 943-953.

[296] X. Lin, Y. Chen, Z. Fang, et al., “Effects of Cytomegalovirus Infection on Extravillous Trophoblast Cells Invasion and Immune Function of NK Cells at the Maternal-Fetal Interface,” Journal of Cellular and Molecular Medicine 24, no. 19 (2020): 11170-11176.

[297] Y. Ding, M. Lavaert, S. Grassmann, et al., “Distinct Developmental Pathways Generate Functionally Distinct Populations of Natural Killer Cells,” Nature Immunology 25, no. 7 (2024): 1183-1192.

[298] E. Caselli, D. Bortolotti, R. Marci, et al., “HHV-6A Infection of Endometrial Epithelial Cells Induces Increased Endometrial NK Cell-Mediated Cytotoxicity,” Frontiers in Microbiology 8 (2017): 2525.

[299] S. Sen Santara, Â. C. Crespo, S. Mulik, et al., “Decidual NK Cells Kill Zika Virus-Infected Trophoblasts,” Proceedings of the National Academy of Sciences of the United States of America 118, no. 47 (2021): e2115410118.

[300] C. Maucourant, G. A. Nonato Queiroz, A. Corneau, et al., “NK Cell Responses in Zika Virus Infection Are Biased Towards Cytokine-Mediated Effector Functions,” Journal of Immunology 207, no. 5 (2021): 1333-1343.

[301] D. Vota, M. Torti, D. Paparini, et al., “Zika Virus Infection of First Trimester Trophoblast Cells Affects Cell Migration, Metabolism and Immune Homeostasis Control,” Journal of Cellular Physiology 236, no. 7 (2021): 4913-4925.

[302] L. J. Juttukonda, E. M. Wachman, J. Boateng, K. Clarke, J. Snyder-Cappione, and E. S. Taglauer, “The Impact of Maternal SARS-CoV-2 Vaccination and First Trimester Infection on Feto-Maternal Immune Responses,” American Journal of Reproductive Immunology 88, no. 6 (2022): e13625.

[303] J. R. Habel, B. Y. Chua, L. Kedzierski, et al., “Immune Profiling of SARS-CoV-2 Infection During Pregnancy Reveals NK Cell and γδ T Cell Perturbations,” JCI Insight 8, no. 7 (2023): e167157.

[304] A. Lu-Culligan, A. R. Chavan, P. Vijayakumar, et al., “Maternal Respiratory SARS-CoV-2 Infection in Pregnancy Is Associated With a Robust Inflammatory Response at the Maternal-Fetal Interface,” Med 2, no. 5 (2021): 591-610.

[305] J. Gonçalves, M. Melro, M. Alenquer, et al., “Balance Between Maternal Antiviral Response and Placental Transfer of Protection in Gestational SARS-CoV-2 Infection,” JCI Insight 8, no. 17 (2023): e167140.

[306] M. Carbonnel, C. Daclin, N. Tarantino, et al., “Plasticity of Natural Killer Cells in Pregnant Patients Infected With SARS-CoV-2 and Their Neonates During Childbirth,” Frontiers in Immunology 13 (2022): 893450.

[307] J. Applebaum, L. A. Humphries, E. Kravitz, et al., “Impact of Coronavirus Disease 2019 Vaccination on Live Birth Rates After In Vitro Fertilization,” Fertility and Sterility 121, no. 3 (2024): 452-459.

[308] S. Perdu, B. Castellana, Y. Kim, K. Chan, L. DeLuca, and A. G. Beristain, “Maternal Obesity Drives Functional Alterations in Uterine NK Cells,” JCI Insight 1, no. 11 (2016): e85560.

[309] V. J. Parker, M. E. Solano, P. C. Arck, and A. J. Douglas, “Diet-Induced Obesity May Affect the Uterine Immune Environment in Early-Mid Pregnancy, Reducing NK-Cell Activity and Potentially Compromising Uterine Vascularization,” International Journal of Obesity 38, no. 6 (2014): 766-774.

[310] B. Castellana, S. Perdu, Y. Kim, et al., “Maternal Obesity Alters Uterine NK Activity Through a Functional KIR2DL1/S1 Imbalance,” Immunology and Cell Biology 96, no. 8 (2018): 805-819.

[311] Y. Li, J. Chen, Y. Lin, et al., “Obesity Challenge Drives Distinct Maternal Immune Response Changes in Normal Pregnant and Abortion-Prone Mouse Models,” Frontiers in Immunology 12 (2021): 694077.

[312] S. Yu, R. Lian, C. Chen, et al., “Impact of Body Mass Index on Peripheral and Uterine Immune Status in the Window of Implantation in Patients With Recurrent Reproductive Failure,” Human Fertility (Cambridge, England) 26, no. 5 (2023): 1322-1333.

[313] M. Palacz and K. Tremellen, “High Body Mass Index Is Associated With an Expansion of Endometrial T Regulatory Cell and Macrophage Populations,” Journal of Reproductive Immunology 129 (2018): 36-39.

[314] S. Sureshchandra, B. M. Doratt, H. True, et al., “Multimodal Profiling of Term Human Decidua Demonstrates Immune Adaptations With Pregravid Obesity,” Cell Reports 42, no. 7 (2023): 112769, https://doi.org/10.1016/j.celrep.2023.112769.

[315] B. Sato, S. Kanai, D. Sakaguchi, et al., “Suppressive Role of Lactoferrin in Overweight-Related Female Fertility Problems,” Nutrients 14, no. 5 (2022): 938.

[316] Y. Xiong, Y. Wang, M. Wu, et al., “Aberrant NK Cell Profile in Gestational Diabetes Mellitus With Fetal Growth Restriction,” Frontiers in Immunology 15 (2024): 1346231, https://doi.org/10.3389/fimmu.2024.1346231.

[317] C.-L. Lee, P. C. N. Chiu, P.-C. Pang, et al., “Glycosylation Failure Extends to Glycoproteins in Gestational Diabetes Mellitus: Evidence From Reduced α2-6 Sialylation and Impaired Immunomodulatory Activities of Pregnancy-Related Glycodelin-A,” Diabetes 60, no. 3 (2011): 909-917.

[318] A. Musumeci, C. J. McElwain, S. Manna, F. McCarthy, and C. McCarthy, “Exposure to Gestational Diabetes Mellitus Increases Subclinical Inflammation Mediated in Part by Obesity,” Clinical and Experimental Immunology 216, no. 3 (2024): 280-292.

[319] Y. Lin, H. Wang, W. Wang, S. Zeng, Y. Zhong, and D.-J. Li, “Prevention of Embryo Loss in Non-Obese Diabetic Mice Using Adoptive ITGA2(+)ISG20(+) Natural Killer-Cell Transfer,” Reproduction 137, no. 6 (2009): 943-955.

[320] A. Lapolla, C. Betterle, M. Sanzari, et al., “An Immunological and Genetic Study of Patients With Gestational Diabetes Mellitus,” Acta Diabetologica 33, no. 2 (1996): 139-144.

[321] B. Groen, G. A. Uuldriks, P. de Vos, J. T. Visser, T. P. Links, and M. M. Faas, “Impaired Trophoblast Invasion and Increased Numbers of Immune Cells at Day 18 of Pregnancy in the Mesometrial Triangle of Type 1 Diabetic Rats,” Placenta 36, no. 2 (2015): 142-149.

[322] S. D. Burke, H. Dong, A. D. Hazan, and B. A. Croy, “Aberrant Endometrial Features of Pregnancy in Diabetic NOD Mice,” Diabetes 56, no. 12 (2007): 2919-2926.

[323] S. D. Burke, A. V. C. Seaward, H. Ramshaw, et al., “Homing Receptor Expression Is Deviated on CD56+ Blood Lymphocytes During Pregnancy in Type 1 Diabetic Women,” PLoS One 10, no. 3 (2015): e0119526.

[324] C. C. P. Hara, E. L. França, D. L. G. Fagundes, et al., “Characterization of Natural Killer Cells and Cytokines in Maternal Placenta and Fetus of Diabetic Mothers,” Journal of Immunology Research 2016 (2016): 7154524.

[325] Y. Li, S. Yu, C. Huang, et al., “Evaluation of Peripheral and Uterine Immune Status of Chronic Endometritis in Patients With Recurrent Reproductive Failure,” Fertility and Sterility 113, no. 1 (2020): 187-196.

[326] X. Chen, Y. Liu, Y. Zhao, et al., “Association Between Chronic Endometritis and Uterine Natural Killer Cell Density in Women With Recurrent Miscarriage: Clinical Implications,” Journal of Obstetrics and Gynaecology Research 46, no. 6 (2020): 858-863.

[327] M. Surcel, I. A. Neamtiu, D. Muresan, et al., “Killer Cell Immunoglobulin-Like Receptor Genotypes and Reproductive Outcomes in a Group of Infertile Women: A Romanian Study,” Diagnostics (Basel) 13, no. 19 (2023): 3048.

[328] D. Fan, X. Wang, Z. Shi, et al., “Understanding Endometriosis From an Immunomicroenvironmental Perspective,” Chinese Medical Journal 136, no. 16 (2023): 1897-1909.

[329] L. Wang, L. Li, Y. Li, et al., “A History of Endometriosis Is Associated With Decreased Peripheral NK Cytotoxicity and Increased Infiltration of Uterine CD68+ Macrophages,” Frontiers in Immunology 12 (2021): 711231, https://doi.org/10.3389/fimmu.2021.711231.

[330] D. Gagné, M. Rivard, M. Pagé, K. Shazand, P. Hugo, and D. Gosselin, “Blood Leukocyte Subsets Are Modulated in Patients With Endometriosis,” Fertility and Sterility 80, no. 1 (2003): 43-53.

[331] H.-L. Yang, W.-J. Zhou, K.-K. Chang, et al., “The Crosstalk Between Endometrial Stromal Cells and Macrophages Impairs Cytotoxicity of NK Cells in Endometriosis by Secreting IL-10 and TGF-β,” Reproduction 154, no. 6 (2017): 815-825.

[332] S.-W. Guo, Y. Du, and X. Liu, “Platelet-Derived TGF-β1 Mediates the Down-Modulation of NKG2D Expression and May Be Responsible for Impaired Natural Killer (NK) Cytotoxicity in Women With Endometriosis,” Human Reproduction 31, no. 7 (2016): 1462-1474.

[333] S. Saeki, A. Fukui, C. Mai, R. Takeyama, A. Yamaya, and H. Shibahara, “Co-Expression of Activating and Inhibitory Receptors on Peritoneal Fluid NK Cells in Women With Endometriosis,” Journal of Reproductive Immunology 155 (2023): 103765.

[334] Y.-J. Kang, I. C. Jeung, A. Park, et al., “An Increased Level of IL-6 Suppresses NK Cell Activity in Peritoneal Fluid of Patients With Endometriosis via Regulation of SHP-2 Expression,” Human Reproduction 29, no. 10 (2014): 2176-2189.

[335] I. González-Foruria, P. Santulli, S. Chouzenoux, F. Carmona, F. Batteux, and C. Chapron, “Soluble Ligands for the NKG2D Receptor Are Released During Endometriosis and Correlate With Disease Severity,” PLoS One 10, no. 3 (2015): e0119961.

[336] R. Galandrini, M. G. Porpora, A. Stoppacciaro, et al., “Increased Frequency of Human Leukocyte Antigen-E Inhibitory Receptor CD94/NKG2A-Expressing Peritoneal Natural Killer Cells in Patients With Endometriosis,” Fertility and Sterility 89, no. 5 (2008): 1490-1496.

[337] U. Thiruchelvam, M. Wingfield, and C. O'Farrelly, “Increased uNK Progenitor Cells in Women With Endometriosis and Infertility Are Associated With Low Levels of Endometrial Stem Cell Factor,” American Journal of Reproductive Immunology 75, no. 4 (2016): 493-502.

[338] H. Peng, L. Weng, S. Lei, et al., “Hypoxia-Hindered Methylation of PTGIS in Endometrial Stromal Cells Accelerates Endometriosis Progression by Inducing CD16- NK-Cell Differentiation,” Experimental & Molecular Medicine 54, no. 7 (2022): 890-905.

[339] J. Mei, W.-J. Zhou, X.-Y. Zhu, et al., “Suppression of Autophagy and HCK Signaling Promotes PTGS2high FCGR3- NK Cell Differentiation Triggered by Ectopic Endometrial Stromal Cells,” Autophagy 14, no. 8 (2018): 1376-1397.

[340] J.-J. Yu, H.-T. Sun, Z.-F. Zhang, et al., “IL15 Promotes Growth and Invasion of Endometrial Stromal Cells and Inhibits Killing Activity of NK Cells in Endometriosis,” Reproduction 152, no. 2 (2016): 151-160.

[341] D. A. Clark, A. Reihani, J. L. Arredondo, K. Ask, and W. G. Foster, “CD200S-Positive Granulated Lymphoid Cells in Endometrium Appear to Be CD56-Positive Uterine NK Cells,” Journal of Reproductive Immunology 150 (2022): 103477.

[342] E. Giuliani, K. L. Parkin, B. A. Lessey, S. L. Young, and A. T. Fazleabas, “Characterization of Uterine NK Cells in Women With Infertility or Recurrent Pregnancy Loss and Associated Endometriosis,” American Journal of Reproductive Immunology 72, no. 3 (2014): 262-269.

[343] B. V. Dons'koi, S. M. Baksheev, I. O. Sudoma, et al., “A Blinded Investigation: Accentuated NK Lymphocyte CD335 (NKp46) Expression Predicts Pregnancy Failures,” Diagnostics (Basel) 13, no. 11 (2023): 1845, https://doi.org/10.3390/diagnostics13111845.

[344] D. Hornung, E. Fujii, K. H. Lim, J. L. Vigne, M. T. McMaster, and R. N. Taylor, “Histocompatibility Leukocyte Antigen-G Is Not Expressed by Endometriosis or Endometrial Tissue,” Fertility and Sterility 75, no. 4 (2001): 814-817.

[345] Y.-C. Chou, C.-H. Chen, M.-J. Chen, et al., “Killer Cell Immunoglobulin-Like Receptors (KIR) and Human Leukocyte Antigen-C (HLA-C) Allorecognition Patterns in Women With Endometriosis,” Scientific Reports 10, no. 1 (2020): 4897.

[346] Z.-Z. Lai, H.-L. Yang, J.-W. Shi, et al., “Protopanaxadiol Improves Endometriosis Associated Infertility and Miscarriage in Sex Hormones Receptors-Dependent and Independent Manners,” International Journal of Biological Sciences 17, no. 8 (2021): 1878-1894.

[347] B. Zhang, W.-J. Zhou, C.-J. Gu, et al., “The Ginsenoside PPD Exerts Anti-Endometriosis Effects by Suppressing Estrogen Receptor-Mediated Inhibition of Endometrial Stromal Cell Autophagy and NK Cell Cytotoxicity,” Cell Death & Disease 9, no. 5 (2018): 574.

[348] J. Zhou, H. Chen, X. Xu, et al., “Uterine Damage Induces Placenta Accreta and Immune Imbalance at the Maternal-Fetal Interface in the Mouse,” Placenta 119 (2022): 8-16.

[349] L. Qi, Y. Li, L. Zhang, et al., “Immune and Oxidative Stress Disorder in Ovulation-Dysfunction Women Revealed by Single-Cell Transcriptome,” Frontiers in Immunology 14 (2023): 1297484.

[350] R. Hou, R. Huang, Y. Zhou, et al., “Single-Cell Profiling of the Microenvironment in Decidual Tissue From Women With Missed Abortions,” Fertility and Sterility 119, no. 3 (2023): 492-503.

[351] D. Chakraborty, M. A. K. Rumi, T. Konno, and M. J. Soares, “Natural Killer Cells Direct Hemochorial Placentation by Regulating Hypoxia-Inducible Factor Dependent Trophoblast Lineage Decisions,” Proceedings of the National Academy of Sciences of the United States of America 108, no. 39 (2011): 16295-16300.

[352] Z. Chen, F. Han, Y. Du, H. Shi, and W. Zhou, “Hypoxic Microenvironment in Cancer: Molecular Mechanisms and Therapeutic Interventions,” Signal Transduction and Targeted Therapy 8, no. 1 (2023): 70.

[353] S. Yan, J. Dong, C. Qian, et al., “The mTORC1 Signaling Support Cellular Metabolism to Dictate Decidual NK Cells Function in Early Pregnancy,” Frontiers in Immunology 13 (2022): 771732.

[354] C. J. Williams, A. Chu, W. N. Jefferson, et al., “Epithelial Membrane Protein 2 (EMP2) Deficiency Alters Placental Angiogenesis, Mimicking Features of Human Placental Insufficiency,” Journal of Pathology 242, no. 2 (2017): 246-259.

[355] A. Chu, S.-Y. Kok, J. Tsui, M.-C. Lin, B. Aguirre, and M. Wadehra, “Epithelial Membrane Protein 2 (Emp2) Modulates Innate Immune Cell Population Recruitment at the Maternal-Fetal Interface,” Journal of Reproductive Immunology 145 (2021): 103309.

[356] D. Li and J. Li, “Association of miR-34a-3p/5p, miR-141-3p/5p, and miR-24 in Decidual Natural Killer Cells With Unexplained Recurrent Spontaneous Abortion,” Medical Science Monitor 22 (2016): 922-929.

[357] W. Chaiwangyen, J. M. Murrieta-Coxca, R. R. Favaro, et al., “MiR-519d-3p in Trophoblastic Cells: Effects, Targets and Transfer to Allogeneic Immune Cells via Extracellular Vesicles,” International Journal of Molecular Sciences 21, no. 10 (2020): 3458.

[358] I. Manaster, D. Goldman-Wohl, C. Greenfield, et al., “MiRNA-Mediated Control of HLA-G Expression and Function,” PLoS One 7, no. 3 (2012): e33395.

[359] Q. Huang, J. Ding, M. Gong, M. Wei, Q. Zhao, and J. Yang, “Effect of miR-30e Regulating NK Cell Activities on Immune Tolerance of Maternal-Fetal Interface by Targeting PRF1,” Biomedicine & Pharmacotherapy 109 (2019): 1478-1487.

[360] C. Carlino, M. R. Rippo, R. Lazzarini, et al., “Differential microRNA Expression Between Decidual and Peripheral Blood Natural Killer Cells in Early Pregnancy,” Human Reproduction 33, no. 12 (2018): 2184-2195.

[361] A. Pelosi, C. Alicata, N. Tumino, et al., “An Anti-Inflammatory microRNA Signature Distinguishes Group 3 Innate Lymphoid Cells From Natural Killer Cells in Human Decidua,” Frontiers in Immunology 11 (2020): 133, https://doi.org/10.3389/fimmu.2020.00133.

[362] Q. Chen, P.-C. Pang, M. E. Cohen, et al., “Evidence for Differential Glycosylation of Trophoblast Cell Types,” Molecular & Cellular Proteomics 15, no. 6 (2016): 1857-1866.

[363] S. Borowski, I. Tirado-Gonzalez, N. Freitag, M. G. Garcia, G. Barrientos, and S. M. Blois, “Altered Glycosylation Contributes to Placental Dysfunction Upon Early Disruption of the NK Cell-DC Dynamics,” Frontiers in Immunology 11 (2020): 1316.

[364] J. Yin, J. W. Leavenworth, Y. Li, et al., “Ezh2 Regulates Differentiation and Function of Natural Killer Cells Through Histone Methyltransferase Activity,” Proceedings of the National Academy of Sciences of the United States of America 112, no. 52 (2015): 15988-15993.

[365] L. Zhu, M. Liu, S. Zhang, et al., “Foxp3 TSDR Hypermethylation Is Correlated With Decreased Tregs in Patients With Unexplained Recurrent Spontaneous Abortion,” Reproductive Sciences 28, no. 2 (2021): 470-478.

[366] S. K. Lee, J. Y. Kim, A. R. Han, et al., “Intravenous Immunoglobulin G Improves Pregnancy Outcome in Women With Recurrent Pregnancy Losses With Cellular Immune Abnormalities,” American Journal of Reproductive Immunology 75, no. 1 (2016): 59-68.

[367] R. Ramos-Medina, A. García-Segovia, J. Gil, et al., “Experience in IVIg Therapy for Selected Women With Recurrent Reproductive Failure and NK Cell Expansion,” American Journal of Reproductive Immunology 71, no. 5 (2014): 458-466.

[368] M. Moraru, J. Carbone, D. Alecsandru, et al., “Intravenous Immunoglobulin Treatment Increased Live Birth Rate in a Spanish Cohort of Women With Recurrent Reproductive Failure and Expanded CD56(+) Cells,” American Journal of Reproductive Immunology 68, no. 1 (2012): 75-84.

[369] L. Heilmann, M. Schorsch, and T. Hahn, “CD3-CD56+CD16+ Natural Killer Cells and Improvement of Pregnancy Outcome in IVF/ICSI Failure After Additional IVIG-Treatment,” American Journal of Reproductive Immunology 63, no. 3 (2010): 263-265.

[370] R. Perricone, G. Di Muzio, C. Perricone, et al., “High Levels of Peripheral Blood NK Cells in Women Suffering From Recurrent Spontaneous Abortion Are Reverted From High-Dose Intravenous Immunoglobulins,” American Journal of Reproductive Immunology 55, no. 3 (2006): 232-239.

[371] M. J. van den Heuvel, C. G. Peralta, K. Hatta, V. K. Han, and D. A. Clark, “Decline in Number of Elevated Blood CD3(+) CD56(+) NKT Cells in Response to Intravenous Immunoglobulin Treatment Correlates With Successful Pregnancy,” American Journal of Reproductive Immunology 58, no. 5 (2007): 447-459.

[372] H. Yamada, M. Deguchi, Y. Maesawa, et al., “Medium-Dose Intravenous Immunoglobulin Therapy for Women With Six or More Recurrent Miscarriages,” Journal of Reproductive Immunology 109 (2015): 48-51.

[373] J. E. Ruiz, J. Y. Kwak, L. Baum, et al., “Intravenous Immunoglobulin Inhibits Natural Killer Cell Activity In Vivo in Women With Recurrent Spontaneous Abortion,” American Journal of Reproductive Immunology 35, no. 4 (1996): 370-375, https://doi.org/10.1111/j.1600-0897.1996.tb00496.x.

[374] M. Morikawa, H. Yamada, E. H. Kato, et al., “Massive Intravenous Immunoglobulin Treatment in Women With Four or More Recurrent Spontaneous Abortions of Unexplained Etiology: Down-Regulation of NK Cell Activity and Subsets,” American Journal of Reproductive Immunology 46, no. 6 (2001): 399-404.

[375] H. Yamada, M. Deguchi, S. Saito, et al., “High Doses of Intravenous Immunoglobulin Stimulate Regulatory T Cell and Suppress Natural Killer Cell in Women With Recurrent Pregnancy Loss,” Journal of Reproductive Immunology 158 (2023): 103977.

[376] M. Ahmadi, M. Ghaebi, S. Abdolmohammadi-Vahid, et al., “NK Cell Frequency and Cytotoxicity in Correlation to Pregnancy Outcome and Response to IVIG Therapy Among Women With Recurrent Pregnancy Loss,” Journal of Cellular Physiology 234, no. 6 (2019): 9428-9437.

[377] M. Ahmadi, S. Abdolmohammadi-Vahid, M. Ghaebi, et al., “Effect of Intravenous Immunoglobulin on Th1 and Th2 Lymphocytes and Improvement of Pregnancy Outcome in Recurrent Pregnancy Loss (RPL),” Biomedicine & Pharmacotherapy 92 (2017): 1095-1102.

[378] B. M. Cohen and S. Machupalli, “Use of Gammaglobulin to Lower Elevated Natural Killer Cells in Patients With Recurrent Miscarriage,” Journal of Reproductive Medicine 60, no. 7-8 (2015): 294-300.

[379] D. A. Clark, K. Wong, D. Banwatt, et al., “CD200-Dependent and nonCD200-Dependent Pathways of NK Cell Suppression by Human IVIG,” Journal of Assisted Reproduction and Genetics 25, no. 2-3 (2008): 67-72, https://doi.org/10.1007/s10815-008-9202-9.

[380] R. G. Roussev, S. C. Ng, and C. B. Coulam, “Natural Killer Cell Functional Activity Suppression by Intravenous Immunoglobulin, Intralipid and Soluble Human Leukocyte Antigen-G,” American Journal of Reproductive Immunology 57, no. 4 (2007): 262-269.

[381] R. G. Roussev, B. Acacio, S. C. Ng, and C. B. Coulam, “Duration of Intralipid's Suppressive Effect on NK Cell's Functional Activity,” American Journal of Reproductive Immunology 60, no. 3 (2008): 258-263.

[382] N. Lédée, C. Vasseur, M. Petitbarat, et al., “Intralipid® May Represent a New Hope for Patients With Reproductive Failures and Simultaneously an Over-Immune Endometrial Activation,” Journal of Reproductive Immunology 130 (2018): 18-22.

[383] L. Meng, J. Lin, L. Chen, et al., “Effectiveness and Potential Mechanisms of Intralipid in Treating Unexplained Recurrent Spontaneous Abortion,” Archives of Gynecology and Obstetrics 294, no. 1 (2016): 29-39.

[384] S. Quenby, R. Farquharson, M. Young, and G. Vince, “Successful Pregnancy Outcome Following 19 Consecutive Miscarriages: Case Report,” Human Reproduction 18, no. 12 (2003): 2562-2564.

[385] M.-Y. Thum, S. Bhaskaran, H. I. Abdalla, B. Ford, N. Sumar, and A. Bansal, “Prednisolone Suppresses NK Cell Cytotoxicity In Vitro in Women With a History of Infertility and Elevated NK Cell Cytotoxicity,” American Journal of Reproductive Immunology 59, no. 3 (2008): 259-265.

[386] S. Cooper, S. M. Laird, N. Mariee, T. C. Li, and M. Metwally, “The Effect of Prednisolone on Endometrial Uterine NK Cell Concentrations and Pregnancy Outcome in Women With Reproductive Failure. A Retrospective Cohort Study,” Journal of Reproductive Immunology 131 (2019): 1-6.

[387] C. Vitale, F. Cottalasso, E. Montaldo, L. Moretta, and M. C. Mingari, “Methylprednisolone Induces Preferential and Rapid Differentiation of CD34+ Cord Blood Precursors Toward NK Cells,” International Immunology 20, no. 4 (2008): 565-575.

[388] J. Won, D. Lee, Y.-G. Lee, S.-H. Hong, J. H. Kim, and Y.-J. Kang, “The Therapeutic Effects and Optimal Timing of Granulocyte Colony Stimulating Factor Intrauterine Administration During IVF-ET,” Life Sciences 317 (2023): 121444.

[389] M. Cozzolino, L. Pellegrini, S. Tartaglia, et al., “Subcutaneous G-CSF Administration Improves IVF Outcomes in Patients With Recurrent Implantation Failure Presenting a KIR/HLA-C Mismatch,” Journal of Reproductive Immunology 165 (2024): 104310, https://doi.org/10.1016/j.jri.2024.104310.

[390] J. Fu, L. Li, L. Qi, and L. Zhao, “A Randomized Controlled Trial of Etanercept in the Treatment of Refractory Recurrent Spontaneous Abortion With Innate Immune Disorders,” Taiwanese Journal of Obstetrics & Gynecology 58, no. 5 (2019): 621-625.

[391] T. Zhang, C. Huang, Y. Du, et al., “Successful Treatment With Intrauterine Delivery of Dexamethasone for Repeated Implantation Failure,” American Journal of Reproductive Immunology 78, no. 6 (2017): e12766.

[392] E. V. Woon, A. Day, T. Bracewell-Milnes, V. Male, and M. Johnson, “Immunotherapy to Improve Pregnancy Outcome in Women With Abnormal Natural Killer Cell Levels/Activity and Recurrent Miscarriage or Implantation Failure: A Systematic Review and Meta-Analysis,” Journal of Reproductive Immunology 142 (2020): 103189.

[393] L. Aslanian-Kalkhoran, A. Kamrani, I. Alipourfard, et al., “The Effect of Lymphocyte Immunotherapy (LIT) in Modulating Immune Responses in Patients With Recurrent Pregnancy Loss (RPL),” International Immunopharmacology 121 (2023): 110326, https://doi.org/10.1016/j.intimp.2023.110326.

[394] Y. Tao, Y.-H. Li, D. Zhang, et al., “Decidual CXCR4+ CD56bright NK Cells as a Novel NK Subset in Maternal-Foetal Immune Tolerance to Alleviate Early Pregnancy Failure,” Clinical and Translational Medicine 11, no. 10 (2021): e540.

[395] H. S. Koo, J. Kwak-Kim, H. J. Yi, et al., “Resistance of Uterine Radial Artery Blood Flow Was Correlated With Peripheral Blood NK Cell Fraction and Improved With Low Molecular Weight Heparin Therapy in Women With Unexplained Recurrent Pregnancy Loss,” American Journal of Reproductive Immunology 73, no. 2 (2015): 175-184.

[396] K. Kolanska, Y. Dabi, A. Dechartres, et al., “Unexplained Recurrent Miscarriages: Predictive Value of Immune Biomarkers and Immunomodulatory Therapies for Live Birth,” American Journal of Reproductive Immunology 86, no. 2 (2021): e13425.

[397] M. F. Gomaa, A. G. Elkholy, M. M. El-Said, and N. E. Abdel-Salam, “Combined Oral Prednisolone and Heparin Versus Heparin: The Effect on Peripheral NK Cells and Clinical Outcome in Patients With Unexplained Recurrent Miscarriage. A Double-Blind Placebo Randomized Controlled Trial,” Archives of Gynecology and Obstetrics 290, no. 4 (2014): 757-762.

[398] G. Sacks and J. Zhang, “Prednisolone and Enoxaparin (Clexane) Therapy (‘the Bondi Protocol’) for Repeated IVF Failure,” American Journal of Reproductive Immunology 88, no. 5 (2022): e13616.

[399] J. H. Kim, S. H. Kim, N. Yang, Y. Ko, S. R. Lee, and H. D. Chae, “Outcomes of Empirical Treatment With Intravenous Immunoglobulin G Combined With Low-Dose Aspirin in Women With Unexplained Recurrent Pregnancy Loss,” Journal of Korean Medical Science 37, no. 25 (2022): e200.

[400] K. Ota, T. Takahashi, A. Han, S. Damvaeba, H. Mizunuma, and J. Kwak-Kim, “Effects of MTHFR C677T Polymorphism on Vitamin D, Homocysteine and Natural Killer Cell Cytotoxicity in Women With Recurrent Pregnancy Losses,” Human Reproduction 35, no. 6 (2020): 1276-1287.

[401] K. Ota, S. Dambaeva, A.-R. Han, K. Beaman, A. Gilman-Sachs, and J. Kwak-Kim, “Vitamin D Deficiency May Be a Risk Factor for Recurrent Pregnancy Losses by Increasing Cellular Immunity and Autoimmunity,” Human Reproduction 29, no. 2 (2014): 208-219.

[402] P. Yang and F. Lu, “Study on the Immunomodulatory Mechanism of Vitamin D in Patients With Unexplained Recurrent Spontaneous Abortion,” Heliyon 10, no. 6 (2024): e27280.

[403] X. Chen, B. Yin, R.-C. Lian, et al., “Modulatory Effects of Vitamin D on Peripheral Cellular Immunity in Patients With Recurrent Miscarriage,” American Journal of Reproductive Immunology 76, no. 6 (2016): 432-438.

[404] L. Wu, J. A. Vendiola, M. D. Salazar Garcia, et al., “Poor Ovarian Response Is Associated With Serum Vitamin D Levels and Pro-Inflammatory Immune Responses in Women Undergoing In-Vitro Fertilization,” Journal of Reproductive Immunology 136 (2019): 102617, https://doi.org/10.1016/j.jri.2019.102617.

[405] I. Bubanovic, “1alpha,25-Dihydroxy-Vitamin-D3 as New Immunotherapy in Treatment of Recurrent Spontaneous Abortion,” Medical Hypotheses 63, no. 2 (2004): 250-253.

[406] J. Najbauer, J. Szekeres-Bartho, and G. J. Tigyi, “Modulation of Cell-Cell and Cell-Antigen Interactions by 1,25-Dihydroxyvitamin D3 and Vitamin D3 Sulfate In Vitro: A Study on Pregnancy Lymphocytes and Hybridoma Cells,” Immunology Letters 20, no. 4 (1989): 317-322.

[407] J. Fan, J. Zhao, J. Zhang, et al., “Vitamin D Supplementation Selectively Affects Peripheral Lymphocyte Subsets in Infertile Women,” Patient Preference and Adherence 18 (2024): 2125-2134, https://doi.org/10.2147/PPA.S470258.

[408] K. N. Evans, L. Nguyen, J. Chan, et al., “Effects of 25-Hydroxyvitamin D3 and 1,25-Dihydroxyvitamin D3 on Cytokine Production by Human Decidual Cells,” Biology of Reproduction 75, no. 6 (2006): 816-822.

[409] K. Ota, S. Dambaeva, M. W.-I. Kim, et al., “1,25-Dihydroxy-Vitamin D3 Regulates NK-Cell Cytotoxicity, Cytokine Secretion, and Degranulation in Women With Recurrent Pregnancy Losses,” European Journal of Immunology 45, no. 11 (2015): 3188-3199, https://doi.org/10.1002/eji.201545541.

[410] J. A. Tamblyn, L. E. Jeffery, R. Susarla, et al., “Transcriptomic Analysis of Vitamin D Responses in Uterine and Peripheral NK Cells,” Reproduction 158, no. 2 (2019): 211-221.

[411] A. N. Al Balawi, N. A. N. Alblwi, R. Soliman, et al., “Impact of Vitamin D Deficiency on Immunological and Metabolic Responses in Women With Recurrent Pregnancy Loss: Focus on VDBP/HLA-G1/CTLA-4/ENTPD1/Adenosine-Fetal-Maternal Conflict Crosstalk,” BMC Pregnancy and Childbirth 24, no. 1 (2024): 709.

[412] P. Vacca, C. Vitale, E. Montaldo, et al., “CD34+ Hematopoietic Precursors Are Present in Human Decidua and Differentiate Into Natural Killer Cells Upon Interaction With Stromal Cells,” Proceedings of the National Academy of Sciences of the United States of America 108, no. 6 (2011): 2402-2407.

[413] J. Gleason, Y. Zhao, I. Raitman, L. Kang, S. He, and R. Hariri, “Human Placental Hematopoietic Stem Cell Derived Natural Killer Cells (CYNK-001) Mediate Protection Against Influenza a Viral Infection,” Human Vaccines & Immunotherapeutics 18, no. 5 (2022): 2055945.

[414] S. Derniame, J. Perazzo, F. Lee, et al., “Differential Effects of Mycophenolate Mofetil and Cyclosporine A on Peripheral Blood and Cord Blood Natural Killer Cells Activated With Interleukin-2,” Cytotherapy 16, no. 10 (2014): 1409-1418.

[415] B. Jin, X. Ding, J. Dai, et al., “Deciphering Decidual Deficiencies in Recurrent Spontaneous Abortion and the Therapeutic Potential of Mesenchymal Stem Cells at Single-Cell Resolution,” Stem Cell Research & Therapy 15, no. 1 (2024): 228.

[416] F. Rezaei Kahmini, S. Shahgaldi, and S. M. Moazzeni, “Mesenchymal Stem Cells Alter the Frequency and Cytokine Profile of Natural Killer Cells in Abortion-Prone Mice,” Journal of Cellular Physiology 235, no. 10 (2020): 7214-7223.

[417] D. Chatterjee, N. Marquardt, D. M. Tufa, et al., “Human Umbilical Cord-Derived Mesenchymal Stem Cells Utilize Activin-A to Suppress Interferon-γ Production by Natural Killer Cells,” Frontiers in Immunology 5, no. 662 (2014): 662, https://doi.org/10.3389/fimmu.2014.00662.

[418] D. Zheng, X. Wang, Z. Zhang, et al., “Engineering of Human Mesenchymal Stem Cells Resistant to Multiple Natural Killer Subtypes,” International Journal of Biological Sciences 18, no. 1 (2022): 426-440.

[419] X.-H. Zhong, Z.-X. Zhou, T.-S. Li, E.-Q. Wang, W.-Y. Shi, and S.-M. Chu, “Anti-Abortive Effect of Radix Scutellariae and Rhizoma Atractylodis in Mice,” American Journal of Chinese Medicine 30, no. 1 (2002): 109-117.

[420] S.-L. Yang, T.-T. Niu, X.-L. Li, D.-J. Li, M.-Q. Li, and H.-Y. Wang, “Bu-Shen-Yi-Qi Formula Impairs Cytotoxicity of NK Cells by Up-Regulating IDO Expression in Trophoblasts,” Gynecological Endocrinology 34, no. 8 (2018): 675-679.

[421] B. V. Dons'koi, V. P. Chernyshov, D. V. Osypchuk, and S. M. Baksheev, “Repeated Cupping Manipulation Temporary Decreases Natural Killer Lymphocyte Frequency, Activity and Cytotoxicity,” Journal of Integrative Medicine 14, no. 3 (2016): 197-202.

[422] C. M. da Bronzon Costa, M. Del Vecchio Filipin, F. H. Santello, et al., “Zinc Supplementation: Immune Balance of Pregnancy During the Chronic Phase of the Chagas Disease,” Acta Parasitologica 65, no. 3 (2020): 599-609, https://doi.org/10.2478/s11686-020-00188-0.

[423] K. Katano, M. Ogasawara, T. Aoyama, Y. Ozaki, S. Kajiura, and K. Aoki, “Clinical Trial of Immunostimulation With a Biological Response Modifier in Unexplained Recurrent Spontaneous Abortion Patients,” Journal of Clinical Immunology 17, no. 6 (1997): 472-477.

[424] L. Wang, Z. Yin, Y. Shen, et al., “Targeting Decidual CD16+ Immune Cells With Exosome-Based Glucocorticoid Nanoparticles for Miscarriage,” Advanced Science (2024): e2406370.

[425] L. Zhang, X. Xie, Y. Zhou, et al., “Gestational Exposure to Titanium Dioxide Nanoparticles Impairs the Placentation Through Dysregulation of Vascularization, Proliferation and Apoptosis in Mice,” International Journal of Nanomedicine 13 (2018): 777-789.

[426] M. Jerzak, M. Kniotek, J. Mrozek, A. Górski, and W. Baranowski, “Sildenafil Citrate Decreased Natural Killer Cell Activity and Enhanced Chance of Successful Pregnancy in Women With a History of Recurrent Miscarriage,” Fertility and Sterility 90, no. 5 (2008): 1848-1853.

[427] M. Kniotek, M. Zych, A. Roszczyk, M. Szafarowska, and M. M. Jerzak, “Decreased Production of TNF-α and IL-6 Inflammatory Cytokines in Non-Pregnant Idiopathic RPL Women Immunomodulatory Effect of Sildenafil Citrate on the Cellular Response of Idiopathic RPL Women,” Journal of Clinical Medicine 10, no. 14 (2021): 3115.

[428] M. El-Far, A. E.-G. El-Motwally, I. A. Hashem, and N. Bakry, “Biochemical Role of Intravaginal Sildenafil Citrate as a Novel Antiabortive Agent in Unexplained Recurrent Spontaneous Miscarriage: First Clinical Study of Four Case Reports From Egypt,” Clinical Chemistry and Laboratory Medicine 47, no. 11 (2009): 1433-1438.

[429] R. G. Roussev, B. V. Dons'koi, C. Stamatkin, et al., “Preimplantation Factor Inhibits Circulating Natural Killer Cell Cytotoxicity and Reduces CD69 Expression: Implications for Recurrent Pregnancy Loss Therapy,” Reproductive Biomedicine Online 26, no. 1 (2013): 79-87, https://doi.org/10.1016/j.rbmo.2012.09.017.

[430] E. Zehorai, T. Gross Lev, E. Shimshoni, et al., “Enhancing Uterine Receptivity for Embryo Implantation Through Controlled Collagenase Intervention,” Life Science Alliance 7, no. 10 (2024): e202402656.

[431] N. Liu, J. Chen, Y. He, et al., “Effects of Maternal L-Proline Supplementation on Inflammatory Cytokines at the Placenta and Fetus Interface of Mice,” Amino Acids 52, no. 4 (2020): 587-596.

[432] C. Helige, G. Hagendorfer, J. Smolle, and G. Dohr, “Uterine Natural Killer Cells in a Three-Dimensional Tissue Culture Model to Study Trophoblast Invasion,” Laboratory Investigation 81, no. 8 (2001): 1153-1162.

[433] L. Richardson, E. Radnaa, R. C. V. Lintao, et al., “A Microphysiological Device to Model the Choriodecidual Interface Immune Status During Pregnancy,” Journal of Immunology 210, no. 9 (2023): 1437-1446.

[434] W. Jia, L. Ma, X. Yu, et al., “Human CD56+CD39+ dNK Cells Support Fetal Survival Through Controlling Trophoblastic Cell Fate: Immune Mechanisms of Recurrent Early Pregnancy Loss,” National Science Review 11, no. 6 (2024): nwae142.

[435] A.-C. Lundell, I. Nordström, K. Andersson, et al., “IFN Type I and II Induce BAFF Secretion From Human Decidual Stromal Cells,” Scientific Reports 7 (2017): 39904, https://doi.org/10.1038/srep39904.

[436] E. C. Co, M. Gormley, M. Kapidzic, et al., “Maternal Decidual Macrophages Inhibit NK Cell Killing of Invasive Cytotrophoblasts During Human Pregnancy,” Biology of Reproduction 88, no. 6 (2013): 155.

[437] J. H. Blokhuis, H. G. Hilton, L. A. Guethlein, et al., “KIR2DS5 Allotypes That Recognize the C2 Epitope of HLA-C Are Common Among Africans and Absent From Europeans,” Immunity, Inflammation and Disease 5, no. 4 (2017): 461-468.

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