Abstract
IL-40 is a recently described cytokine associated with malignancies and autoimmune rheumatic diseases. It is mainly produced by immune cells, in particular by activated B lymphocytes and neutrophils.
Local and systemic up-regulation of IL-40 was documented in several rheumatic diseases. Levels of IL-40 are elevated in the serum and in the synovial fluid of RA patients and correlate with neutrophil activation and the levels of autoantibodies.
Serum IL-40 decreases following different therapies in RA and participates in the regulation of inflammation and tissue remodeling via activation of neutrophils and synovial fibroblasts. Increased expression of IL-40 was also demonstrated in the serum and the salivary glands of patients with Sjögren's syndrome.
Based on the recent data, IL-40 is a multifunctional cytokine implicated in the pathogenesis of autoimmune inflammatory diseases.