Cytokines

Cytokines are small proteins secreted by cells of both the innate and adaptive immune systems and can regulate diverse functions in the immune response. Dysregulation of cytokine secretion and their consequent signaling networks are an important component of the pathogenesis of autoimmune disease. In systemic lupus erythematosus (SLE), a number of cytokines are aberrantly expressed, such as type I interferon, IL-6, and IL-17, and their effects on immune cells contribute to autoimmunity, facilitate abnormal cellular and humoral responses, and also directly mediate tissue pathology and damage.^1,2 On the other hand, aberrantly reduced levels of key cytokines such as IL-2 lead to defective regulatory T cell responses and promote autoimmunity. A key feature of lupus is the presence of autoantibodies, and therefore T cell-driven activation of B cells is a central aspect of lupus pathogenesis. Therefore, cytokines that promote the aberrant activation and function of T and B cells and their interactions are crucial drivers of disease.