Objective Inflammation and fibrosis are key features of diabetic nephropathy (DN). Triptolide (TP) exhibits anti-inflammatory and anti-fibrotic properties, though its mechanisms of action in DN remain unclear. CREKA (Cys-Arg-Glu-Lys-Ala) is a pentapeptide that specifically binds to fibronectin (FN), and the CREKA-modified liposome (CREKA-Lip) represents a novel FN-targeted drug delivery system. This study aimed to investigate the role of TP in diabetic db/db mice and determine whether encapsulation within CREKA-Lip enhances therapeutic efficacy while reducing the multi-organ toxicity of TP.

Methods Eight-week-old diabetic db/db mice received tail vein injections twice weekly with vehicle, free TP, or CREKA-Lip/TP for 10 weeks. Urine and serum parameters were measured, and kidney, heart, liver, and testis tissues were collected for pathological evaluation. Protein-protein interaction networks were constructed using Cytoscape and its plug-ins to identify core targets and elucidate the therapeutic mechanism of TP against DN. Inflammatory, fibrotic, apoptotic, and lipid metabolism markers were evaluated in the kidneys of diabetic mice with DN and in high glucose-treated mouse mesangial cells and podocytes using qPCR, Western blot, immunohistochemistry, and immunofluorescence assays.

Results TP administration reduced fasting blood glucose levels and glomerular mesangial expansion in diabetic mice. TP significantly suppressed renal inflammation, fibrosis, and apoptosis while enhancing lipid metabolism. Integration of network pharmacology, molecular docking, and transcriptomics revealed that TP ameliorated DN by inhibiting the JAK2-STAT1 signaling pathway. In vitro, TP inhibited high glucose-induced phosphorylation of JAK2 and STAT1, reduced collagen production in mesangial cells, decreased apoptosis, and improved lipid metabolism in podocytes. Moreover, CREKA-Lip/TP exhibited superior efficacy compared with free TP, with a more sustained reduction in urine albumin-to-creatinine ratio and greater inhibition of mesangial expansion. Notably, CREKA-Lip/TP treatment did not induce systemic toxicity.

Conclusion TP improves renal inflammation, fibrosis, apoptosis, and lipid homeostasis, thereby ameliorating DN by inhibiting JAK2-STAT1 activation. Targeted delivery of TP via FN-binding CREKA-Lip enhances therapeutic efficacy while minimizing multi-organ toxicity.