Grupo de Biología del Cartílago, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), Spain; Centre for Neuroscience and Cell Biology and Faculty of Pharmacy, University of Coimbra, Portugal.
Grupo de Biología del Cartílago, Servicio de Reumatología, Instituto de Investigación Biomédica de A Coruña (INIBIC), Complexo Hospitalario Universitario de A Coruña (CHUAC), Spain.
Osteoarthritis Cartilage. 2016 Apr;24(4):731-9. doi: 10.1016/j.joca.2015.10.017. Epub 2015 Nov 5.
Autophagy, a key homeostasis mechanism, is defective in Osteoarthritis (OA) and Type 2 Diabetes (T2D). T2D has been proposed as a risk factor for OA. We hypothesized that diabetes impairs articular cartilage integrity by decreasing autophagy. Our objective was to investigate the effects of high glucose and insulin, characteristics of T2D, on cartilage homeostasis.
Immortalized human chondrocytes (TC28a2) and primary human chondrocytes (HC) were cultured in 25 mM or 0 mM glucose and treated with insulin (10, 100, 500 nM) for 2, 6 or 24 h. Activity of LC3-II, Akt and rpS6 was evaluated by Western blotting (WB). Human cartilage explants were cultivated with 25 mM glucose and insulin (100,1000 nM) for 24 h to evaluate histopathology. MMP-13 and IL-1β expression was determined by immunohistochemistry and WB. Effects of Rapamycin (10 μM) were analyzed by WB. LC3 and rpS6 expression was determined by WB in chondrocytes from Healthy, Non Diabetic-OA and Diabetic-OA patients.
Insulin downregulates autophagy by reducing LC3 II expression and increasing Akt and rpS6 phosphorylation. Loss of proteoglycans and increased MMP-13 and IL-1β expression was observed after insulin treatment. Autophagy activation by rapamycin reversed insulin effects. Importantly, chondrocytes from diabetic-OA patients showed decreased LC3 and increased p-rpS6 expression compared to Healthy and Non-Diabetic OA patients.
These results suggest that decreased autophagy might be a mechanism by which diabetes influences cartilage degradation. Pharmacological activation of autophagy may be an effective therapeutic approach to prevent T2D-induced cartilage damage.
自噬是一种关键的内稳态机制，在骨关节炎（OA）和 2 型糖尿病（T2D）中存在缺陷。T2D 已被提议为 OA 的危险因素。我们假设糖尿病通过降低自噬来损害关节软骨的完整性。我们的目的是研究高血糖和胰岛素（T2D 的特征）对软骨内稳态的影响。
培养永生化人软骨细胞（TC28a2）和原代人软骨细胞（HC），分别在 25mM 或 0mM 葡萄糖中培养，并在 10、100 和 500nM 胰岛素作用 2、6 或 24 小时。通过 Western blot（WB）评估 LC3-II、Akt 和 rpS6 的活性。用人软骨外植体在 25mM 葡萄糖和胰岛素（100、1000nM）中培养 24 小时，以评估组织病理学。通过免疫组织化学和 WB 测定 MMP-13 和 IL-1β 的表达。通过 WB 分析雷帕霉素（10μM）的作用。通过 WB 测定健康、非糖尿病性 OA 和糖尿病性 OA 患者软骨细胞中的 LC3 和 rpS6 表达。
胰岛素通过降低 LC3 II 表达和增加 Akt 和 rpS6 磷酸化来下调自噬。胰岛素处理后观察到蛋白聚糖丢失和 MMP-13 和 IL-1β 表达增加。雷帕霉素的自噬激活逆转了胰岛素的作用。重要的是，与健康和非糖尿病性 OA 患者相比，糖尿病性 OA 患者的软骨细胞中 LC3 表达降低，p-rpS6 表达增加。
这些结果表明，自噬减少可能是糖尿病影响软骨降解的一种机制。自噬的药理学激活可能是预防 T2D 诱导的软骨损伤的有效治疗方法。
