Single-Cell Sequencing Uncovers a TMSB10-Expressing Fibroblast Subpopulation Driving Renal Fibrosis in Diabetic Nephropathy.

Introduction: Diabetic nephropathy (DN) is a leading cause of end-stage kidney disease (ESKD), with renal fibrosis as a key pathological hallmark. However, the cellular and molecular drivers of fibrosis remain incompletely defined. Here, we employed single-cell RNA sequencing (scRNA-seq) to delineate pro-fibrotic cell subsets and their key regulatory factors in human DN kidneys, providing a higher-resolution view compared to previous fibrosis-related scRNA-seq studies. Methods: Publicly available scRNA-seq datasets from human DN and control kidneys were analyzed to identify fibrosis-associated fibroblast subsets. A Tmsb10-high fibroblast population was prioritized. Functional validation was performed through Tmsb10 knockdown in NIH-3T3 fibroblasts and in a diabetic mouse model, followed by assessment of fibrosis markers, extracellular matrix (ECM) deposition, and TGF-β/SMAD signaling. Results: scRNA-seq revealed a significant expansion of Tmsb10-high fibroblasts in DN kidneys, exhibiting strong enrichment of ECM-related and TGF-β/SMAD-responsive genes. Tmsb10 knockdown reduced Fn1, Col1a1, and α-Sma expression by approximately 50-70% and markedly attenuated ECM accumulation in vivo. Mechanistically, TMSB10 deficiency suppressed phosphorylation of SMAD2/3, mitigating fibroblast activation and matrix deposition. Discussion: This study identifies TMSB10 as a novel fibroblast-specific regulator of renal fibrosis in DN, acting through the TGF-β/SMAD pathway. These findings expand current understanding of fibroblast heterogeneity and highlight TMSB10 as a potential therapeutic target for DN and other fibrotic diseases. Limitations include validation in a limited sample size and the use of murine fibroblast models, warranting further confirmation in human primary cells.