Other studies have found that hypoxia and proinflammatory cytokines can play a synergistic role in enhancing osteoclast-mediated bone erosion and MMPs expression, thereby aggravating RA bone destruction, mainly through IL-1β/HIF-1α, IL-17/HIF-1α and other pathways (61, 62). This evidence concerns the gene HIF1A and rheumatoid arthritis.