An increasing number of studies have demonstrated a critical role of FABP4 secretion by macrophages in diabetes, hepatocellular carcinoma, and autoimmune disease via the regulation of inflammation and angiogenesis.10,33,34 In addition to IL-1β, IL-6, and TNFα, we found that FABP4 secretion by M1-polarized macrophages played a vital role in RA progression. Here, IL1B is linked to rheumatoid arthritis.