CAPG Promotes Renal Fibrosis by Regulating γδ T Cells

Background: Renal fibrosis is the final manifestation of chronic kidney disease regardless of etiology. γδ T cells are characterized by unique TCR composition (γ and δ chains) and play an important role in organs fibrosis. However, the relationship between γδ T cells and renal fibrosis and its molecular mechanism are poorly defined. Our study aimed to elucidate the regulatory role of Capping Actin Protein, Gelsolin Like (CAPG) in γδ T cell-driven renal fibrosis. Methods: Murine models of renal fibrosis were established via unilateral ureteral obstruction (UUO) and folic acid (FA). Single-cell RNA sequencing (scRNA-seq) was performed on FA-induced fibrotic kidneys. We generated Capg knockout (Capg-/-) and Wild type (Capg+/+) mice and utilized FA and UUO models. Further, γδ T cells isolated from UUO kidneys of Capg+/+ mice were adoptively transferred into Capg-/- mice via tail vein, followed by UUO. Kidney sections were subjected to renal histopathological, flow cytometry, Western blotting, immunofluorescence (IF). Results: scRNA-seq demonstrated a progressive upregulation of CAPG expression level in T lymphocytes correlating with renal fibrosis severity. After dimensionality reduction cluster analysis of T cell subsets, CAPG was primarily expressed in γδ T cells and Treg cells, with γδ T cell-specific CAPG levels escalating in parallel with fibrosis progression. Flow cytometry exhibited γδ T cells activation in FA- and UUO-induced renal fibrosis, and confirmed CAPG predominantly expressed in γδ T cells compared to CD4+ T cells, CD8+ T cells, double-negative T cells, with significantly elevated CAPG levels in γδ T cells from fibrotic kidney compared to controls. IF revealed co-localization of γδ T cells and CAPG. Knockout of CAPG significantly attenuated renal fibrosis, reduced extracellular matrix deposition, downregulated expression of fibrotic markers, and decreased γδ T cells infiltration. During renal fibrosis, γδT cells predominantly exhibited γδT17 phenotype characterized by IL-17A secretion, which was substantially reduced upon CAPG deletion. The adoptive transfer of γδ T cells partially reversed the anti-fibrotic effects of Capg -/- mice in the process of renal fibrosis. Conclusion: γδ T cells are activated in response to renal fibrosis. High CAPG expression in γδ T cells is associated with their activation and IL-17A secretion. CAPG is a potential therapeutic target for γδ T cell-mediated renal fibrosis. Funding: Government Support – Non-U.S.