IL17A and osteoporosis: It is already known that skin inflammation in psoriasis patients will lead to increased levels of IL-17A in serum, specifically inhibiting bone formation of osteoblasts and resulting in osteoporosis.11 Other studies have shown that in the process of normal aging, the secretion of cystatin-A in aging epidermal cells is reduced, which is an important reason for affecting osteoporosis.12 These evidences suggest that there is a strong connection between bone and skin.