Dapagliflozin suppress endoplasmic reticulum stress mediated apoptosis of chondrocytes by activating Sirt1

Osteoarthritis (OA) is a common joint disease characterized by inflammation and cartilage degeneration. Accumulating evidences support that endoplasmic reticulum (ER) stress induced OA chondrocytes apoptosis. The hypoglycemic and anti-inflammatory properties render Dapagliflozin (DAPA) effective in reducing ER stress on cells. However, its impact and potential mechanisms on the OA pathology are still obscure. The present study aimed to investigate whether DAPA attenuates ER stress in chondrocytes by activating sirt1 and delays the progression of OA.In vitro, we first investigated the effect of DAPA on chondrocytes viability with IL-1β or not for 24 or 48 h. Then, chondrocytes were treated with 10 ng/ml IL-1β and 10 μM dapagliflozin with10 μM thapsigargin, 5 μM SRT1460 or not. Chondrocytes apoptosis in each group were detected by Tunel staining and flow cytometric. Immunofluorescence staining was applied to quantify the expression levels of cleaved caspase-3, Sirt1 and CHOP in chondrocytes. Inhibition of ER stress in chondrocytes associated with sirt1 activation were verified by PCR and western blotting. In addition, the effects of DAPA on cartilage were validated by a series of experiments in OA rat model, such as micro-CT, histological and immunohistochemical assay.The data demonstrated that DAPA alleviates IL-1β induced ER stress related chondrocytes apoptosis, and PCR and western blotting data confirmed that DAPA inhibits the PERK-eIF2α-CHOP pathway by activating Sirt1. Besides, immunohistochemical results showed that DAPA enhanced the expression of Sirt1 and Collagen II in OA rats, and inhibited the expression of CHOP and cleaved caspase-3. Meanwhile, histological staining and micro-CT photography also confirmed that DAPA alleviated inflammation and cartilage degeneration in OA rat.The study demonstrated the relationship of ER stress and inflammation in the progression of OA, and verified that DAPA could inhibit PERK-eIF2α-CHOP axis of the ER stress response by activating Sirt1 in IL-1β treated rat chondrocytes and potentially prevent the OA development.