Tumour necrosis factor-α promotes BMHSC differentiation by increasing P2X7 receptor in oestrogen-deficient osteoporosis

The exact mechanism of tumour necrosis factor α (TNF-α) promoting osteoclast differentiation is not completely clear. A variety of P2 purine receptor subtypes have been confirmed to be widely involved in bone metabolism. Thus, the purpose of this study was to explore whether P2 receptor is involved in the differentiation of osteoclasts. Mouse bone marrow haematopoietic stem cells (BMHSCs) were co-cultured with TNF-α to explore the effect of TNF-α on osteoclast differentiation and bone resorption capacity in vitro, and changes in the P2 receptor were detected at the same time. The P2 receptor was silenced and overexpressed to explore the effect on differentiation of BMHSCs into osteoclasts. In an in vivo experiment, the animal model of PMOP was established in ovariectomized mice, and anti-TNF-α intervention was used to detect the ability of BMHCs to differentiate into osteoclasts as well as the expression of the P2 receptor. It was confirmed in vitro that TNF-α at a concentration of 20 ng/mL up-regulated the P2X7 receptor of BMHSCs through the PI3K/Akt signalling pathway, promoted BMHSCs to differentiate into a large number of osteoclasts and enhanced bone resorption. In vivo experiments showed that more P2X7 receptor positive osteoclasts were produced in postmenopausal osteoporotic mice. Anti-TNF-α could significantly delay the progression of PMOP by inhibiting the production of osteoclasts. Overall, our results revealed a novel function of the P2X7 receptor and suggested that suppressing the P2X7 receptor may be an effective strategy to delay bone formation in oestrogen deficiency-induced osteoporosis.