Tanshinone IIA suppresses endoplasmic reticulum stress-mediated IRE1α/TXNIP/NLRP3 pathway to mitigate pyroptosis in type 2 diabetic osteoporosis

Type 2 diabetic osteoporosis (T2DOP) is a chronic skeletal disorder affecting bone structure and strength. Research has shown that endoplasmic reticulum stress (ERS) activates the NLRP3 inflammasome and osteoblast pyroptosis through inositol-requiring enzyme 1 alpha (IRE1α) and its interaction with thioredoxin-interacting protein (TXNIP). Tanshinone IIA (Tan IIA), a naturally occurring lipophilic diterpene derived from Salvia miltiorrhiza, inhibits the activation of IRE1α. This study explored Tan IIA’s therapeutic effects on T2DOP. MC3T3-E1 cells were cultured in a high-glucose medium to replicate conditions characteristic of the diabetic environment. Additionally, a T2DOP mouse model was developed through the intraperitoneal injection of streptozotocin in conjunction with a 60 %kacl high fat diet. Tan IIA was administered at different concentrations. Cell viability, differentiation and mineralization was assessed via CCK-8 assays, alkaline phosphatase staining, and Alizarin Red S staining. Serum biochemical markers were quantified using ELISA kits, while bone quality was evaluated using micro-CT and histological analysis. The mechanism was confirmed by Western blot, immunohistochemistry, RT-qPCR, molecular docking, and Cellular Thermal Shift Assay. Results showed Tan IIA improved insulin resistance, reduced inflammation and oxidative stress, and restored bone mass in T2DOP mice. Mechanistically, Tan IIA inhibited the IRE1α/TXNIP/NLRP3 pathway in vivo and in vitro, and ERS inducer tunicamycin attenuated its beneficial effects. The data establish Tan IIA as a promising candidate for treating T2DOP by alleviating osteoblast dysfunction and bone loss via the ERS-mediated IRE1α/TXNIP/NLRP3 pathway and pyroptosis.