CD226 deficiency on regulatory T cells aggravates renal fibrosis via up‐regulation of Th2 cytokines through miR‐340

摘要

In this study, we observed that deletion of CD226 on regulatory T cells (Tregs) precedes renal fibrosis in a mouse unilateral ureteral obstruction (UUO) model. First, we generated Treg‐specific CD226 gene knockout mice (CD226fl/fl Foxp3YFP‐Cre). Next, CD226fl/fl Foxp3YFP‐Cre mice and Foxp3YFP‐Cre control mice were subjected to UUO surgery. Pathologic analysis and Sirius red and Masson's trichrome staining showed that the kidneys of CD226fl/fl Foxp3YFP‐Cre mice following UUO showed much more severe interstitial fibrosis than Foxp3YFP‐Cre control mice at days 10 and 20. Additionally, CD226fl/fl Foxp3YFP‐Cre mice showed increased fibronectin expression, as demonstrated by immunohistochemistry (IHC) staining. Although Treg cell‐restricted CD226 deficiency showed increased Foxp3+ expression, expression of the cell surface functional molecule CD103 was significantly reduced, indicating impaired homeostasis in the Tregs of CD226fl/fl Foxp3YFP‐Cre mice. To better understand CD226 function, RNA sequencing (RNA‐Seq) analysis was conducted in Tregs isolated from CD226fl/fl Foxp3YFP‐Cre and Foxp3YFP‐Cre mice. RNA‐Seq data showed that the helper T cell (Th) 2‐related cytokines IL‐4 and IL‐10 were significantly up‐regulated in CD226 deficient Tregs. In addition, mRNA analysis of kidney samples from the mice following UUO by qPCR also showed increased IL‐4 and IL‐10 expression in CD226fl/fl Foxp3YFP‐Cre mice, as well as elevated TGF‐β1 levels, indicating that CD226 deficiency in Tregs resulted in the acquisition of the ability to produce Th2 cytokines. Finally, we found that microRNA‐340 (miR‐340), which was down‐regulated in Tregs isolated from CD226fl/fl Foxp3YFP‐Cre mice, directly regulated IL‐4 gene expression in vitro. These data suggest that the promotion of CD226 signaling on Tregs is a therapeutic target for renal disease.