Obstructive nephropathy leads to renal fibrosis, and Triggering Receptor Expressed on Myeloid Cells 2 (TREM2) drives this macrophage-mediated process, but its mechanism remains unclear. This study investigated TREM2's role in macrophage polarisation and renal fibrosis progression. In human fibrotic kidneys, TREM2 expression was significantly elevated and co-localised with macrophages. Unilateral ureteral obstruction (UUO) modelling in mice recapitulated this upregulation, accompanied by renal fibrosis, M2 macrophage polarisation and glomerular filtration rate (GFR) reduction. Trem2 deficiency (Trem2^−/−) significantly attenuated these pathological changes in UUO mice, preserving GFR. Separately, TREM2 inhibitory peptide sequence IA9 administration reduced renal fibrosis and M2 polarisation in UUO mice. In bone marrow-derived macrophages (BMDMs), Trem2 deficiency suppressed IL-4/IL-13-induced M2 polarisation, migration and β-catenin expression. Critically, lithium chloride (LiCl)-mediated β-catenin stabilisation rescued these impairments in Trem2^−/− BMDMs. In conclusion, TREM2 promotes renal fibrosis by activating β-catenin signalling to drive profibrotic M2 macrophage responses, establishing TREM2 blockade as a therapeutic strategy for obstructive nephropathy.

Human embryos undergo pivotal morphogenetic remodelling shortly after implantation. The understanding of this crucial stage is severely impeded by the scarcity of embryonic samples and ethical constraints. Pluripotent stem cells with the competence for somatic and germline differentiation serve as in vitro models of epiblast. In this study, we established human formative pluripotent stem cell-like cells (hfPSC-LCs) from naïve human embryonic stem cells (hESCs), conventional hESCs, human induced pluripotent stem cells (hiPSCs), as well as human blastocysts using the three-dimensional (3D) Matrigel culture system. Similar to pre-gastrula stage epiblast, hfPSC-LCs self-organise into self-renewing colonies with an apical lumen and exhibit several hallmarks of formative pluripotency, consistent with the properties observed in mouse fPSCs. Notably, single cells of hfPSC-LCs could differentiate into amnion-like precursor cells (hALPCs) which are transcriptionally and morphologically similar to the bona fide amnion. Meanwhile, hfPSC-LCs directly respond to primordial germ cell (PGC) induction signals, generating PGC-like cells (PGCLCs) either as single-cell aggregates or intact colonies, with an efficiency of approximately 50%. Chromatin accessibility analysis revealed that the differentiation capacity of hfPSC-LCs for gametes and amnion lineages might correlate with the accessible chromatin architecture of PGC and amnion associated genes. Loss of 3D-Matrigel niche disrupts formative pluripotency in both mouse and human, manifesting as downregulated formative markers and compromised differentiation capacity. Collectively, our findings establish hfPSC-LCs as a 3D model for investigating formative pluripotency of humans, thereby probably addressing a critical gap in the understanding of human pluripotency transitions.

Mucosal-associated invariant T (MAIT) cells, representing one of the most abundant subsets of unconventional T cells, have been shown to play a significant role in regulating immune responses. However, their immunoregulatory roles in the context of liver transplantation (LT) immunity remain largely undefined. To address this, we conducted single-cell RNA/TCR sequencing, flow cytometry, and multiplex immunohistochemical (mIHC) assays to identify the proportion and characteristics of CD8+ MAIT cells in humans and mice following liver transplantation. We found that CD8+ MAIT cells were prominently represented in the single-cell CD8 profiles of human transplanted livers, demonstrating strong signalling associations with macrophages, whilst the fractional populations of MAIT1 and MAIT17 were distinctly clustered. In parallel, the proportion of CD8+ MAIT cells was significantly elevated in mouse LT models, revealing a dynamic trend where percentages increased at 1 and 2 weeks post-transplant, peaking at 3 weeks. Furthermore, using established MR1 knockout (MR1KO) LT mice, we observed that mice lacking MAIT cells exhibited milder rejection responses, indicating that MR1 mediates rejection by influencing the remodelling of the TCR repertoire after transplantation. Collectively, our study reveals that MAIT cells play a critical role in LT rejection, as MR1KO alleviated inflammatory responses and mitigated rejection via TCR repertoire remodelling. By mapping the dynamic changes of MAIT cells throughout the rejection process, these findings lay the groundwork for further investigations into the role of these cells in transplant immunity.

Heat stress is a common challenge for cells, causing multiple types of cellular damage while triggering complex stress responses, including the highly conserved mechanism known as the heat shock response (HSR). However, the subcellular coordination of these stress responses remains poorly understood. In this study, we identify reversible nuclear morphological changes under heat stress, characterised by kidney-shaped invaginations. These nuclear invaginations are associated with intermediate filament collapse and the regional clustering of organelles. Through immunofluorescence imaging and proteomic analysis, we further reveal that nuclear invagination regions function as specialised compartments where newly synthesised proteins are concentrated and protein degradation demand is heightened. Moreover, this compartmentalization is not only essential for cellular adaptation and recovery from heat stress but also correlates with the differential heat tolerance across cell lines. Our findings highlight a previously unappreciated mechanism by which cells spatially reorganise protein metabolism to optimise stress responses, providing new insights into cellular stress adaptation.

Ovarian endometriosis (OEM) is characterised by ectopic endometrial tissue growth within the ovary. In these ectopic lesions, the ectopic epithelium plays a crucial role in OEM progression and has been associated with malignant transformation in a subset of cases. However, conventional histology limits understanding of ectopic epithelial distribution, structure, and its perivascular microenvironment, thus impeding pathogenesis studies. To address this, we employed a modified tissue-clearing method and three-dimensional (3D) imaging to systematically characterise OEM, revealing key, previously unreported spatial characteristics. We found significantly higher densities of ectopic epithelium and vasculature in the outer cystic wall versus the inner. Furthermore, our method improved the detection rate of ectopic epithelium and revealed its morphological polymorphism at both tissue and cellular levels. Besides, we demonstrated that vessels preferentially cluster around ectopic epithelium, with their distribution pattern strongly linked to the location of ectopic epithelium. Strikingly, we observed endometrial-like structures in lesional vasculature in 3 of 49 cases, representing a novel morphological observation that warrants further investigation. This study significantly advances our understanding of OEM histopathology, offering insights for clinical diagnosis and treatment.

Liver cancer remains a leading cause of cancer-related mortality worldwide, with limited durable responses to conventional therapies. Cancer vaccines utilising the immune system offer a promising alternative. Here, we developed a prophylactic whole-cell tumour vaccine by engineering Hepa 1-6 cells to express murine granulocyte-macrophage colony-stimulating factor (mGM-CSF), and investigated its anti-tumour efficacy and underlying mechanisms. The Hepa 1-6-mGM-CSF vaccine provided complete and durable protection against both primary and rechallenge tumour inoculations. Hepa 1-6-mGM-CSF immunisation robustly activated dendritic cells (DCs) and T cells in both lymph nodes and spleen, characterised by enhanced DC maturation and migration, as well as the differentiation of T cells toward cytotoxic and memory phenotypes. Meanwhile, the Hepa 1-6-mGM-CSF vaccine remodelled the tumour microenvironment (TME) toward an immunostimulatory state. Critically, irradiation-induced oxidative stress in mitochondria promoted the release of oxidised mitochondrial DNA (ox-mtDNA), which subsequently activated the cGAS-STING signalling pathway. Ox-mtDNA synergized with vaccine-secreted GM-CSF to promote DC activation, antigen presentation and migration. In summary, our study demonstrates that the Hepa 1-6-mGM-CSF vaccine elicits robust anti-tumour immunity through the coordinated release of ox-mtDNA and GM-CSF, with ox-mtDNA synergistically enhancing immune activation via the cGAS-STING signalling pathway. Collectively, these findings highlight the Hepa 1-6-mGM-CSF vaccine as a promising strategy for liver cancer management.

Liver fibrosis represents a critical pathological stage in chronic liver disease, characterized by excessive activation of hepatic stellate cells (HSCs) and dysregulated immune cell recruitment. Our previous studies demonstrated that overexpressing tyrosine kinase receptor B (TrkB) in HSCs inhibits their activation, thereby alleviating liver fibrosis. However, its functional significance in hepatocytes—the predominant parenchymal cells orchestrating liver homeostasis—remains poorly understood. Here, we investigate the mechanistic interplay between hepatocyte-specific TrkB signalling and liver fibrosis progression. Through integrated in vivo animal models and in vitro two- and three-dimensional systems, we demonstrate that elevated TrkB expression in hepatocytes reduces pro-fibrotic and inflammatory cytokines, attenuates HSC activation via paracrine signalling, and impairs monocyte-derived macrophage (MoMF) recruitment. Mechanistically, TrkB modulates the TGFβ/SMAD3 pathway by inhibiting p-SMAD3 nuclear translocation, thus suppressing FOS transcription. As a core component of the AP-1 transcription factor complex, FOS directly regulates CCL2, a pivotal chemokine for macrophage recruitment. Collectively, these results establish TrkB as a key regulatory node in the TGFβ/SMAD3/FOS/CCL2 signalling cascade, orchestrating macrophage-mediated fibrotic responses in the liver.

Dentine formation constitutes a physiological process precisely regulated by signal transduction modules governing odontoblast differentiation and mineralisation. First, by constructing a single-cell transcriptional landscape of odontogenic tissue, we defined EFNB2+ mesenchymal cells as a primary progenitor cluster, marking the origin of the odontogenic lineage. Integrating CellRank-based fate mapping and SCENIC-based regulon specificity analysis, we identified signal transducer and activator of transcription 3 (STAT3) as a pivotal transcriptional regulator of the odontoblast lineage. Subsequently, in silico perturbations using CellOracle predicted that STAT3 ablation disrupted the developmental vector field, redirecting the fate of mesenchymal precursors away from the odontoblast lineage. To substantiate these bioinformatic predictions, functional validation using shRNA-mediated silencing and pharmacological modulation demonstrated that STAT3 was essential for the proliferation and differentiation capacity of dental mesenchymal cells. Furthermore, we generated conditional knockout mice targeting Stat3 in Osterix-expressing odontoblast progenitors, which consequently exhibited significant dentine dysplasia. Mechanistically, RNA-seq and chromatin immunoprecipitation (ChIP) assays revealed that STAT3 directly bound to the WNT2B promoter, transcriptionally activating the Wnt/β-catenin signalling pathway in dental mesenchymal cells. Overexpression of WNT2B partially rescued the odontogenic defects induced by STAT3 inactivation. This ‘prediction to verification’ study establishes STAT3 as a critical regulator of dentinogenesis and provides potential therapeutic targets for the treatment of dentine developmental disorders and the advancement of dentine regeneration.

Bone morphogenetic protein (BMP) signalling plays a pivotal role in bone regeneration by regulating osteoprogenitor cell (OPC) function, and BMPs have been widely used in clinical treatment. However, their limited specificity for OPCs often lead to side effects, highlighting that the regulatory mechanisms of BMP signalling remain to be further elucidated. BMPR1A, a key type I BMP receptor, has emerged as a critical regulator of bone development, yet its precise role in bone regeneration and downstream mechanisms remains unclear. Using OPC-specific conditional knockout (cKO) and constitutively activated (CA) BMPR1A mouse, we found conditional knockout of BMPR1A in OPCs during the first 2 weeks of healing significantly accelerated bone regeneration. At the cellular level, BMPR1A knockout promoted the proliferation of OPCs, thereby accelerating bone regeneration in cKO mice. Mechanistically, BMPR1A knockout reduced ID1 expression, releasing its inhibition of TCF3, which in turn induced GNG4 expression and ultimately activated the PI3K–AKT pathway. Finally, a double-knockdown cell line further demonstrated the role of the BMPR1A–ID1–TCF3–GNG4 signalling axis. This study reveals the function and mechanism of BMPR1A in bone regeneration and provides new insights for more precise BMP-targeted strategies.

Fatty acid (FA) overload imposes substantial stress on hypothalamic neurons, whilst whether cortical input could improve metabolic resilience of hypothalamic neurons remains poorly understood. Here, we reconstructed human cortical-hypothalamic assembloids (CO-HTO assembloids) to investigate how cortical input modulates hypothalamic responses to FA. Our results revealed that FA could impair neuronal survival, α-MSH secretion, and electrophysiological activity in hypothalamic organoids (HTOs). Remarkably, fusion with cortical organoids (COs) could prevent FA-induced apoptosis and functional defects, preserve mitochondrial respiration, and reduce lipid accumulation in HTOs. Also, transcriptomic and functional analyses revealed that cortical input could activate PGC1α-dependent mitochondrial biogenesis. Furthermore, pharmacological PGC1α activation or glutamate treatment rescued the FA-induced defects in HTOs. Collectively, our findings uncovered a cortico-hypothalamic regulatory axis and found glutamate-driven PGC1α activation might maintain hypothalamic neuronal stability and improve resilience to metabolic stress. Our CO-HTO assembloids provided a promising platform to investigate complex inter-regional communications and related neurological and metabolic disorders.

Sepsis, a life-threatening clinical syndrome precipitated by a maladaptive host response to infection, is associated with substantial morbidity and high mortality rates. Gastrointestinal injury has gained recognition as a pivotal factor driving sepsis progression. Pathogen invasion incites oxidative stress and inflammatory cascades, leading to compromised intestinal barrier integrity and dysregulated local immunity. This results in increased gut permeability and bacterial translocation, fostering a state that can be described as ‘enteric sepsis’. Moreover, multi-organ crosstalk via the gut-liver and gut-brain axes substantially amplifies systemic inflammation. The pathophysiology of sepsis-induced intestinal injury is not yet fully elucidated, and clinically applicable biomarkers or early diagnostic tools remain scarce. Targeted therapeutic strategies have yet to be validated in clinical practice. This article presents a comprehensive review of recent advances in the pathophysiology and underlying mechanisms of sepsis-induced intestinal injury, focusing on the signalling networks that disrupt intestinal homeostasis and immune equilibrium. Particular emphasis is placed on identifying key pathways and candidate biomarkers for early diagnosis and intervention. Additionally, the therapeutic potential of targeted intestinal-protective agents is evaluated, integrating insights from traditional Chinese medicine to propose a combined treatment strategy. Ultimately, this review aims to establish a translational framework to advance clinical management and therapeutic innovation for sepsis-associated intestinal dysfunction.

Lysine L-lactylation (K_L-la) is a newly identified metabolite-derived post-translational modification that directly bridges cellular metabolic states to chromatin regulation and protein function. Mounting evidence shows that K_L-la has pivotal roles in transcription regulation and diverse cellular processes and is implicated in multiple pathophysiological conditions. This review comprehensively examines K_L-la across both histone and non-histone substrates in biology and disease. We first illustrate the historical development of K_L-la and distinguish it from its isomers. We then delineate the enzymes regulating K_L-la, examine its crosstalk with other PTMs, and discuss its roles in cell signalling and other biological processes. Particular emphasis is placed on mechanisms through which K_L-la contributes to various human diseases such as cancer, viral infections, neurodegenerative disorders, cardiovascular conditions, metabolic abnormalities and immune dysregulation. Finally, we provide an in-depth analysis of emerging therapeutic strategies targeting K_L-la and highlight future directions for translating mechanistic insights into clinical applications.