Crosstalk Between Th17 Cells and Renal Tubular Epithelial Cells Promotes Fibrotic Progression in IgA Nephropathy

Abstract

Objective

Th17 cell-mediated immune injury is a crucial factor contributing to tubulointerstitial fibrosis in patients with IgA nephropathy (IgAN). However, the exact mechanisms by which Th17 cells induce tubulointerstitial fibrosis remain to be fully elucidated.

Methods

An IgAN mouse model was established and validated. Transcriptome sequencing, combined with bioinformatics analysis, was carried out to explore the immune injury pathways in renal tissues and the activation pathways in Th17 cells that were co-cultured with tubular epithelial cells. In subsequent experiments, small interfering RNA (siRNA) and overexpression plasmids were used to manipulate cellular targets. Validation was conducted through quantitative real-time polymerase chain reaction (qPCR), Western blotting, and immunofluorescence assays.

Results

Compared with the control mice, IgAN mice exhibited elevated serum creatinine levels and increased urine protein-to-creatinine ratios. Renal pathological examination revealed the characteristic features of IgAN. Transcriptomic analysis of the kidney tissues from the model mice showed the activation of Th17 differentiation pathways, which was further confirmed by immunofluorescence analysis showing increased expression of interleukin-17A (IL-17A). These findings indicate an increased abundance of Th17 cells with potential pathogenic significance. When Th17 cells were co-cultured with tubular epithelial cells, the level of interleukin-9 (IL-9) in the system increased. This increase in IL-9 activated the Janus kinase 1-signal transducer and activator of transcription 3 (JAK1-STAT3) pathway through the IL-9 receptor (IL-9R) and upregulated the signature transcription factor retinoic acid-related orphan receptor gamma (ROR-γ), thus promoting Th17 cell differentiation. When IL-9R was silenced using siRNA or when the activity of STAT3 was inhibited, both the levels of phosphorylated STAT3 (p-STAT3) and ROR-γ decreased. Moreover, IL-17A secreted by Th17 cells promoted the nuclear translocation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in tubular epithelial cells by activating the IL-17 receptor A (IL-17RA)–adaptor protein Act1–tumor necrosis factor receptor-associated factor 6 (TRAF6) complex. This process regulated the production of inflammatory cytokines and drove the initiation and progression of fibrosis. Treatment with a STAT3 inhibitor in IgAN mice led to a reduction in the number of renal Th17 cells and alleviated the fibrotic phenotype.

Conclusion

This study demonstrated that the interaction between Th17 cells and tubular epithelial cells triggers excessive extracellular matrix deposition in the tubulointerstitium, thereby exacerbating the fibrotic phenotype and accelerating the progression of IgAN.

Keywords

IgA nephropathy (IgAN) / Chronic kidney disease (CKD) / Th17 cell / Interleukin 9 receptor (IL-9R) / Signal transducer and activator of transcription 3 (STAT3)

References

[1] StamellouE, SeikritC, TangSCW, et al.IgA nephropathy. Nat Rev Dis Primers., 2023, 9167.

[2] CheungCK, AlexanderS, ReichHN, et al.. The pathogenesis of IgA nephropathy and implications for treatment. Nat Rev Nephrol., 2025, 21(1): 9-23.

[3] SahaMK, JulianBA, NovakJ, et al.. Secondary IgA nephropathy. Kidney Int., 2018, 94(4): 674-681.

[4] BarrattJ, LafayetteRA, ZhangH, et al.. IgA nephropathy: the lectin pathway and implications for targeted therapy. Kidney Int., 2023, 104(2): 254-264.

[5] ChouYL, ChenHL, HsuBG, et al.. Galectin-3 contributes to pathogenesis of IgA nephropathy. Kidney Int., 2024, 106(4): 658-670.

[6] Del VecchioL, AllinoviM, ComolliS, et al.. Drugs in Development to Treat IgA Nephropathy. Drugs., 2024, 84(5): 503-525.

[7] FloegeJ, Bernier-JeanA, BarrattJ, et al.. Treatment of patients with IgA nephropathy: a call for a new paradigm. Kidney Int., 2025, 107(4): 640-651.

[8] KronbichlerA, BajemaI, GeethaD, et al.. Novel aspects in the pathophysiology and diagnosis of glomerular diseases. Ann Rheum Dis., 2023, 82(5): 585-593.

[9] KurtsC, PanzerU, AndersHJ, et al.. The immune system and kidney disease: basic concepts and clinical implications. Nat Rev Immunol., 2013, 13(10): 738-753.

[10] BaiL, LiH, LiJ, et al.. Immunosuppressive effect of artemisinin and hydroxychloroquine combination therapy on IgA nephropathy via regulating the differentiation of CD4+ T cell subsets in rats. Int Immunopharmacol., 2019, 70: 313-323.

[11] DuW, GaoCY, YouX, et al.. Increased proportion of follicular helper T cells is associated with B cell activation and disease severity in IgA nephropathy. Front Immunol., 2022, 13. 901465

[12] HuX, FengJ, ZhouQ, et al.. Respiratory Syncytial Virus Exacerbates Kidney Damages in IgA Nephropathy Mice via the C5a–C5aR1 Axis Orchestrating Th17 Cell Responses. Front Cell Infect Microbiol., 2019, 9151.

[13] ZhangYM, LiuXZ, ZhouXJ, et al.. A Functional Variant rs3093023 in CCR6 Is Associated With IgA Nephropathy by Regulating Th17 Cells in a North Han Chinese Population. Front Immunol., 2021, 12. 600598

[14] HerrnstadtGR, NiehusCB, RamckeT, et al.. The CCR6/CCL20 axis expands RORγt+ Tregs to protect from glomerulonephritis. Kidney Int., 2023, 104(1): 74-89.

[15] HuangJ, LiX, ZhuQ, et al.. Imbalance of Th17 cells, Treg cells and associated cytokines in patients with systemic lupus erythematosus: a meta-analysis. Front Immunol., 2024, 151425847.

[16] ZhangT, HuoH, ZhangY, et al.. Th17 cells: A new target in kidney disease research. Int Rev Immunol., 2024, 43(5): 263-279.

[17] QingJ, LiC, HuX, et al.. Differentiation of T Helper 17 Cells May Mediate the Abnormal Humoral Immunity in IgA Nephropathy and Inflammatory Bowel Disease Based on Shared Genetic Effects. Front Immunol., 2022, 13. 916934

[18] Uriol-RiveraMG, Obrador-MuletA, JuliáMR, et al.. Sequential administration of paricalcitol followed by IL-17 blockade for progressive refractory IgA nephropathy patients. Sci Rep., 2024, 1414866.

[19] WangW, ZhangM, RenX, et al.. Single-cell dissection of cellular and molecular features underlying mesenchymal stem cell therapy in ischemic acute kidney injury. Mol Ther., 2023, 31(10): 3067-3083.

[20] ZhangL, WangZ, WuY, et al.. RasGRP4 aggravates ischemia-reperfusion injury in diabetic kidneys by mediating communication between macrophages and T cells. JCI Insight., 2024, 102. e187653

[21] MillsKHG. IL-17 and IL-17-producing cells in protection versus pathology. Nat Rev Immunol., 2023, 23(1): 38-54.

[22] OharaD, TakeuchiY, HirotaK. Type 17 immunity: novel insights into intestinal homeostasis and autoimmune pathogenesis driven by gut-primed T cells. Cell Mol Immunol., 2024, 21(11): 1183-1200.

[23] LiuY, WangK, LiangX, et al.. Complement C3 Produced by Macrophages Promotes Renal Fibrosis via IL-17A Secretion. Front Immunol., 2018, 92385.

[24] PengX, XiaoZ, ZhangJ, et al.. IL-17A produced by both γδ T and Th17 cells promotes renal fibrosis via RANTES-mediated leukocyte infiltration after renal obstruction. J Pathol., 2015, 235(1): 79-89.

[25] LinCC, ChangTY, LuYC, et al.. TREM-2 mediates dendritic cell-induced NO to suppress Th17 activation and ameliorate chronic kidney diseases. J Mol Med (Berl)., 2022, 100(6): 917-931.

[26] KimD, LangmeadB, SalzbergSL. HISAT: a fast spliced aligner with low memory requirements. Nat Methods., 2015, 12(4): 357-360.

[27] MortazaviA, WilliamsBA, McCueK, et al.. Mapping and quantifying mammalian transcriptomes by RNA-Seq. Nat Methods., 2008, 5(7): 621-628.

[28] RobinsonMD, OshlackA. A scaling normalization method for differential expression analysis of RNA-seq data. Genome Biol., 2010, 113R25.

[29] PerteaM, PerteaGM, AntonescuCM, et al.. StringTie enables improved reconstruction of a transcriptome from RNA-seq reads. Nat Biotechnol., 2015, 33(3): 290-295.

[30] PerteaM, KimD, PerteaGM, et al.. Transcript-level expression analysis of RNA-seq experiments with HISAT. StringTie and Ballgown. Nat Protoc., 2016, 11(9): 1650-1667.

[31] RobinsonMD, McCarthyDJ, SmythGK. edgeR: a Bioconductor package for differential expression analysis of digital gene expression data. Bioinformatics., 2010, 26(1): 139-140.

[32] SchustJ, SperlB, HollisA, et al.. Stattic: a small-molecule inhibitor of STAT3 activation and dimerization. Chem Biol., 2006, 13(11): 1235-1242.

[33] VerasFP, PublioGA, MeloBM, et al.. Pyruvate kinase M2 mediates IL-17 signaling in keratinocytes driving psoriatic skin inflammation. Cell Rep., 2022, 4113. 111897

[34] YokotaT, OmachiK, SuicoMA, et al.. STAT3 inhibition attenuates the progressive phenotypes of Alport syndrome mouse model. Nephrol Dial Transplant., 2018, 33(2): 214-223.

[35] MengT, LiX, AoX, et al.. Hemolytic Streptococcus may exacerbate kidney damage in IgA nephropathy through CCL20 response to the effect of Th17 cells. PLoS One., 2014, 99. e108723

[36] GaoH, SunM, LiA, et al.. Microbiota-derived IPA alleviates intestinal mucosal inflammation through upregulating Th1/Th17 cell apoptosis in inflammatory bowel disease. Gut Microbes., 2025, 1712467235.

[37] DengCC, XuXY, ZhangY, et al.. Single-cell RNA-seq reveals immune cell heterogeneity and increased Th17 cells in human fibrotic skin diseases. Front Immunol., 2024, 151522076.

[38] MotzKM, LinaIA, SamadI, et al.. Sirolimus-eluting airway stent reduces profibrotic Th17 cells and inhibits laryngotracheal stenosis. JCI Insight., 2023, 811. e158456

[39] NowakEC, WeaverCT, TurnerH, et al.. IL-9 as a mediator of Th17-driven inflammatory disease. J Exp Med., 2009, 206(8): 1653-1660.

[40] SalazarY, ZhengX, BrunnD, et al.. Microenvironmental Th9 and Th17 lymphocytes induce metastatic spreading in lung cancer. J Clin Invest., 2020, 130(7): 3560-3575.

[41] ElyamanW, BassilR, BradshawEM, et al.. Notch receptors and Smad3 signaling cooperate in the induction of interleukin-9-producing T cells. Immunity., 2012, 36(4): 623-634.

[42] ElyamanW, KhourySJ. Th9 cells in the pathogenesis of EAE and multiple sclerosis. Semin Immunopathol., 2017, 39(1): 79-87.

[43] ShenJ, ChenY, ZhangY, et al.. Multifaceted roles of IL-17 in bone and tendon health. Int J Biol Macromol., 2025, 294. 139498

[44] ZhangX, LiB, LanT, et al.. The role of interleukin-17 in inflammation-related cancers. Front Immunol., 2024, 151479505.

[45] García-PatiñoMG, Marcial-MedinaMC, Ruiz-MedinaBE, et al.. IL-17 in skin infections and homeostasis. Clin Immunol., 2024, 267. 110352

[46] AbdelnabiMN, HassanGS, ShoukryNH. Role of the type 3 cytokines IL-17 and IL-22 in modulating metabolic dysfunction-associated steatotic liver disease. Front Immunol., 2024, 151437046.

[47] LiuW, WangX, WuW. Role and functional mechanisms of IL-17/IL-17R signaling in pancreatic cancer (Review). Oncol Rep., 2024, 525144.

[48] LiangQ, HeL, WangJ, et al.. Targeting IL-17 and its receptors: A feasible way for natural herbal medicines to modulate fibroblast-like synoviocytes in rheumatoid arthritis. Biochem Pharmacol., 2024, 230Pt 2. 116598

[49] McMurrayJS. A new small-molecule Stat3 inhibitor. Chem Biol., 2006, 13(11): 1123-1124.

[50] LinL, JouD, WangY, et al.. STAT3 as a potential therapeutic target in ALDH+ and CD44+/CD24+ stem cell-like pancreatic cancer cells. Int J Oncol., 2016, 49(6): 2265-2274.

Funding

National Natural Science Foundation of China(82400846)

Open Grant from the Pingyuan Laboratory(2023PYOP-0203)

Young Elite Scientists Sponsorship Program by CAST(2023QNRC001)

Natural Science Foundation of Beijing Municipality(7244407)

RIGHTS & PERMISSIONS

The Author(s), under exclusive licence to Huazhong University of Science and Technology