Abstract
With the ageing of the world population, osteoporosis has become a problem affecting quality of life. According to the traditional view, the causes of osteoporosis mainly include endocrine disorders, metabolic disorders and mechanical factors. However, in recent years, the immune system and immune factors have been shown to play important roles in the occurrence and development of osteoporosis. Among these components, regulatory T (Treg) cells and T helper 17 (Th17) cells are crucial for maintaining bone homeostasis, especially osteoclast differentiation. Treg cells and Th17 cells originate from the same precursor cells, and their differentiation requires involvement of the TGF-β regulated signalling pathway. Treg cells and Th17 cells have opposite functions. Treg cells inhibit the differentiation of osteoclasts in vivo and in vitro, while Th17 cells promote the differentiation of osteoclasts. Therefore, understanding the balance between Treg cells and Th17 cells is anticipated to provide a new idea for the development of novel treatments for osteoporosis.