CD11c+ CD8+ T Cells Reduce Renal Fibrosis Following Ureteric Obstruction by Inducing Fibroblast Apoptosis

Tubulointerstitial fibrosis is a common consequence of various kidney diseases that lead to end-stage renal failure, and lymphocyte infiltration plays an important role in renal fibrosis. We previously found that depletion of cluster of differentiation 8(+) (CD8(+)) T cells increases renal fibrosis following ureteric obstruction, and interferon-gamma (IFN-gamma)-expressing CD8(+) T cells contribute to this process. CD8(+) T cells are cytotoxic T cells; however, whether their cytotoxic effect reduces fibrosis remains unknown. This study showed that CD8(+) T cells isolated from obstructed kidney showed mRNA expression of the cytotoxicity-related genes perforin 1, granzyme A, granzyme B, and FAS ligand; additionally, CD8 knockout significantly reduced the expression levels of these genes in obstructed kidney. Infiltrated CD8(+) T cells were distributed around fibroblasts, and they are associated with fibroblast apoptosis in obstructed kidney. Moreover, CD11c(+) CD8(+) T cells expressed higher levels of the cytotoxicity-related genes than CD11c CD8(+) T cells, and infiltrated CD11c(+) CD8(+) T cells in obstructed kidney could induce fibroblast death in vitro. Results indicated that induction of fibroblast apoptosis partly contributed to the effect of CD8(+) T cells on reduction of renal fibrosis. Given that inflammatory cells are involved in fibrosis, our results suggest that kidney fibrosis is a multifactorial process involving different arms of the immune system.