Multifaceted Roles of IL-26 in Physiological and Pathological Conditions.

Cytokines are a diverse group of signaling proteins that regulate immune responses by mediating cell communication. Among them, interleukins (ILs) play essential roles in immune regulation, influencing diverse cell processes through tightly controlled signaling networks. Dysregulation of interleukin signaling could lead to chronic inflammation, contributing to the development of autoimmune and inflammatory diseases as well as cancer. IL-26, a cytokine of the IL-10 family, has emerged as a unique modulator of immune function. Although structurally related to IL-10 and sharing one of its receptor subunits, IL-26 exerts distinct biological effects, particularly in promoting inflammatory responses and interacting with extracellular DNA to activate immune pathways. Increasing evidence implicates IL-26 in the development of several chronic conditions, such as psoriasis, rheumatoid arthritis, inflammatory bowel disease, asthma, and various types of cancer. This review summarizes current knowledge on IL-26's biology, including its structural and receptor characteristics, immunomodulatory functions, and roles in inflammation and disease. Understanding IL-26's dual functions in normal and inflammatory states may provide insights into novel therapeutic strategies targeting IL-26-mediated pathways in pathological conditions.