Inflammatory Cytokines in Systemic Lupus Erythematosus

Figure 3

Dysregulated cytokine expression by T cells contributes to pathogenesis of SLE. SLE T cells secrete enhanced levels of IL-17 and IL-21 compared to healthy persons. IL-17 induces secretion of chemokines and other proinflammatory cytokines and therefore participates in tissue inflammation and organ damage. IL-21 and IL-17 both promote differentiation of B cells into plasma cells and production of IgG antibodies. IL-21 further maintains and expands occurrence of Th17 cells. In contrast SLE T cells have a defective production of IL-2, which leads to reduced level of regulatory T cells and defective function of T cells, which might also be caused by IL-21. Since IL-2 is crucial for AICD, low levels of IL-2 might be responsible for reduced AICD leading to expansion of autoreactive T cells, which further trigger B-cell activation and tissue inflammation.