The role of Interleukin‐32 in autoimmunity

Abstract Interleukin‐32 (IL‐32) is a pro‐inflammatory cytokine that induces other cytokines involved in inflammation, including tumour necrosis factor (TNF)‐α, IL‐6 and IL‐1β. Recent evidence suggests that IL‐32 has a crucial role in host defence against pathogens, as well as in the pathogenesis of chronic inflammation. Abnormal IL‐32 expression has been linked to several autoimmune diseases, such as rheumatoid arthritis and inflammatory bowel diseases, and a recent study suggested the importance of IL‐32 in the pathogenesis of type 1 diabetes. However, despite accumulating evidence, many molecular characteristics of this cytokine, including the secretory route and the receptor for IL‐32, remain largely unknown. In addition, the IL‐32 gene is found in higher mammals but not in rodents. In this review, we outline the current knowledge of IL‐32 biological functions, properties, and its role in autoimmune diseases. We particularly highlight the role of IL‐32 in rheumatoid arthritis and type 1 diabetes.