Salicin modifies osteoarthritis progression by binding on IRE1α and inhibiting IRE1α mediated endoplasmic reticulum stress

Abstract

AbstractObjectivesTo investigate the effect and mechanisms of salicin (SA) on osteoarthritis (OA) progression.MethodsPrimary rat chondrocytes were stimulated with TNF-α and treated with or without SA. CCK-8 was utilized to determine the cytotoxicity of SA. RT-qPCR, Western Blotting and immunofluorescence staining were used to detect inflammatory factors, cartilage matrix degeneration markers, cell proliferation and apoptosis markers expression at mRNA and protein levels respectively. EdU assay and flow cytometer analysis were utilized for evaluating cell proliferation and apoptosis. RNA-sequencing, molecular docking, drug affinity responsive target stability and WB were applied to clarify mechanisms. Rat OA model was used to evaluate the effect of intra-articular injection of SA on OA progression.ResultsNo obvious cytotoxicity was found with the treatment of 10 μM SA. SA rescued TNF-α induced degeneration of cartilage matrix, inhibition of chondrocytes proliferation, and promotion of chondrocytes apoptosis. In mechanism, we clarified SA could directly bind on IRE1α and occupy IRE1α phosphorylation site, followed with inhibiting IRE1α phosphorylation and regulating IRE1α mediated endoplasmic reticulum (ER) stress by IRE1α-IκBα-p65 signaling. Finally, intra-articular injection of SA loaded PLGA could ameliorate OA progression by inhibiting IRE1α mediated ER stress in OA model.ConclusionsSA alleviates OA by directly binding on ER stress regulator IRE1α and inhibits IRE1α mediated ER stress by IRE1α-IκBα-p65 signaling. Topical use of small molecular drug SA holds the potential of modifying OA progression.