Triptolide Alleviates Podocyte Epithelial-Mesenchymal Transition via Kindlin-2 and EMT-Related TGF-β/Smad Signaling Pathway in Diabetic Kidney Disease.

Diabetes-induced chronic kidney diseases are widespread and decrease the quality of life for millions of affected individuals in China. To date, no therapies effectively alleviate these conditions. Triptolide, a traditionally used Chinese medicine, has shown promise in treating renal diseases. Here, the study aimed to decipher the exact mechanism by which it functions. It was hypothesized that triptolide might prevent the epithelial-mesenchymal transition (EMT) of podocytes by activating the kindlin-2 and TGF-β/Smad pathways. Triptolide or telmisartan was intragastrically administered to 9-week-old db/db and dm/dm mice with diabetic nephropathy (DN) for 12 weeks. In addition, biochemical parameters and body weight were detected. WT-1, nephrin, podocin, E-cadherin, and α-SMA were determined by immunohistochemistry in the renal tissues of treated mice. Protein and mRNA expression of podocyte EMT markers, kindlin-2 and TGF-β/Smad, were analyzed to elucidate the underlying mechanism. It was observed that triptolide treatment relieved structural injuries and functional variations in diabetic mice. It also increased the protein and mRNA levels of nephrin, podocin, and E-cadherin and decreased the expression of α-SMA in diabetic mice. The protein and mRNA expressions of TGF-β1, p-SMAD3, and kindlin-2 decreased in diabetic kidneys following triptolide treatment. The findings demonstrated that triptolide might protect podocytes during DN by inhibiting podocyte EMT through inactivation of kindlin-2, combined with the downregulation of P-SMAD3 in the TGF-β/Smad signaling pathway.