Major depressive disorder (MDD) is a type of mood disorder characterized by a significant and persistent group of depressive symptoms. Gut microbiota may play a critical role in the pathogenesis of MDD. It has been found that the gut microbiota composition of MDD patients is significantly different from that of healthy controls, and depression phenotype can be transferred to rodents by fecal microbiota transplantation. Nevertheless, the mechanism of gut microbiota dysbiosis contributing to depression is complicated, and it is currently accepted that the microbiota-gut-brain axis is a crucial part. A set of probiotics and prebiotics have been found to have antidepressant properties, and related microbial therapies are expected to become an important method for treating depression and other mental diseases in the future.

BACKGROUND:Studies have shown that imbalance of bone metabolism during glucocorticoid-induced osteonecrosis of the femoral head necrosis is closely related to oxidative stress. OBJECTIVE:To investigate the pathological mechanism by which oxidative stress-induced ferroptosis promote apoptosis in osteoblasts involved in steroid-induced osteonecrosis of the femoral head. METHODS:General data and serum specimens were collected from 47 patients with steroid-induced osteonecrosis of the femoral head.In addition,six femoral head specimens were collected from these patients.According to the Association Research Circulation Osseous(ARCO)staging system,serum specimens were grouped into ARCO Ⅱ,Ⅲ,and IV,while femoral head specimens were classified into ARCO Ⅲ and IV.Serum levels of malondialdehyde and superoxide dismutase 1 were measured.The protein expression of superoxide dismutase 1,glutathione peroxidase 4,Bcl-2 in the femoral head was detected and verified by Data independent acquisition(DIA)for quantitative sequencing,western blot and alkaline phosphate detection. RESULTS AND CONCLUSION:The ARCO stage of patients with steroid-induced osteonecrosis of the femoral head was independent of age,sex and necrotic side.The serum levels of malondialdehyde and superoxide dismutase 1 were higher in patients with ARCO stage Ⅲ compared with those with ARCO stage Ⅱ and IV.The results of DIA protein quantification showed that the function of differential proteins was mainly related to redox.The levels of superoxide dismutase 1,glutathione peroxidase 4,and Bcl-2 in the necrotic region were lower than in the normal region,as well as lower in ARCO stage IV than in ARCO stage Ⅲ.Western blot verified the results of DIA protein quantification.The alkaline phosphatase activity was lower in the necrotic region than in the normal region,as well as lower in ARCO stage IV than in ARCO stage Ⅲ.In the necrotic and sclerotic regions,the function of differential proteins was also related to redox,and superoxide dismutase 1,glutathione peroxidase 4,Bcl-2 protein expression and alkaline phosphatase activity were lower in the necrotic area than in the sclerotic region,as well as lower in ARCO stage IV than in ARCO stage Ⅲ.To conclude,glucocorticoids can influence the progression of steroid-induced osteonecrosis of the femoral head by upregulating oxidative stress levels,inducing osteoblast ferroptosis,and inhibiting osteogenic function.