Alleviation of Diabetic Tendon Injury via Activation of Tendon Fibroblasts Autophagy under Berberine Treatment

Berberine (BBR) is an isoquinoline alkaloid isolated from Coptis chinensis and possesses valuable pharmacological activities, including anti-inflammatory, anti-tumor, and alleviating several complications of type 2 diabetes mellitus (T2DM). However, the role of BBR in regulating diabetic tendon injury remains poorly understood. In this study, a rat model of T2DM was constructed, and cell apoptosis and autophagy were assessed in tendon tissues after BBR treatment through TdT-Mediated dUTP nick-end labeling (TUNEL) assay and immunohistochemical analysis. Tendon fibroblasts were obtained from the rat Achilles tendon, and the role of BBR in regulating cell apoptosis, the production of inflammatory cytokines, and autophagy activation were assessed using flow cytometry, quantitative real-time PCR (qRT-PCR), and western blot analysis. We demonstrated that BBR treatment significantly increased autophagy activation and decreased cell apoptosis in tendon tissues of T2DM rats. In tendon fibroblasts, BBR repressed High glucose (HG)-induced cell apoptosis and production of proinflammatory cytokines. HG treatment resulted in a decrease of autophagy activation in tendon fibroblasts, whereas BBR restored autophagy activation. More important, pharmacological inhibition of autophagy by 3-MA weakened the protective effects of BBR against HG-induced tendon fibroblasts injury. Taken together, the current results demonstrate that BBR helps relieve diabetic tendon injury by activating autophagy of tendon fibroblasts.