Abstract

Perirenal fat, due to its anatomical proximity and secretory function, is intimately linked to renal physiology and is a rich source of mesenchymal stem cells (MSCs). However, the impact of exosomes from MSCs derived from perirenal fat under diabetic pathological conditions remains unclear. Exosomes were isolated from perirenal fat-derived MSCs of healthy and diabetic nephropathy (DN) rats. Their pro-inflammatory and pro-fibrotic effects on glomerular mesangial cells were assessed in vitro using ELISA, immunofluorescence, and Western blot. Differentially expressed miRNAs were identified by high-throughput sequencing. The targeting relationship between miR-331-3p and TSC1 was validated by a dual-luciferase reporter assay. Renal function and histopathology were evaluated in a diabetic rat model to assess therapeutic efficacy following miRNA modulation. MSCs from the perirenal fat of DN rats exhibited significant pro-inflammatory and pro-fibrotic properties compared to the healthy control group. miRNA sequencing revealed that miR-331-3p was significantly upregulated in exosomes from DN rats. Mechanistically, miR-331-3p overexpression promoted high glucose-induced inflammation and fibrosis in mesangial cells by directly targeting TSC1, leading to the activation of the mTOR signaling pathway. This effect was reversed by TSC1 overexpression. In vivo, administration of a miR-331-3p antagomir significantly attenuated renal injury in DN rats, whereas its agomir induced nephropathy-like damage in healthy rats. Our findings indicate that perirenal adipose-derived mesenchymal stem cells (ADMSCs) enhanced pro-inflammatory and pro-fibrotic capabilities in the diabetic microenvironment. This effect is mediated by the delivery of miR-331-3p, which promotes inflammation and fibrosis via the TSC1/mTORC1, ultimately impairing renal function in DN.