Interleukin-32 Gamma as a New Face in Inflammatory Bone Diseases

Abstract

Interleukin-32 (IL-32), a recently identified pro-inflammatory cytokine, is involved in the pathogenesis and progression of infections, cancer, chronic inflammation, and autoimmune disease. IL-32γ is the most active isoform in cell death and cell activation among nine distinct isoforms of IL-32. IL-32γ potentiates both osteogenic and osteoclastogenic capacities, and is critical in the coupling of bone resorption and bone formation for maintenance of bone homeostasis. IL-32γ is strongly associated with inflammatory bone disorders such as rheumatoid arthritis, ankylosing spondylitis, and osteoporosis. In this review, we summarize current research on the role of IL-32γ in inflammatory bone disorders, highlighting this cytokine as a novel target for prognostic marker and control of these diseases. (J Rheum Dis 2017;24:14-20)

Role of IL-32 Gamma on Bone Metabolism in Autoimmune Arthritis

“…In RA, which is characterized by chronic synovitis and hyperplasia, the joints are the representative pathological sites of progressive cartilage and bone destruction ( 41 ). Activated macrophages are the predominant cell type in the inflamed synovial tissue and are responsible for promoting inflammation via the production of inflammatory cytokines, such as TNF-α, IL-17, IL-1β, and IL-6 ( 41 ). These cytokines promote the differentiation of preosteoclasts into mature OCs, enhance bone resorption, and prolong OC survival, thereby contributing to bony erosion in inflamed joints ( 42 ).…”