Cytokines and fibrosis.

Inflammation is frequently associated with changes in the surrounding connective tissue. Inflammatory mononuclear cells (MNC) produce biologically active molecules, cytokines (CK), which may regulate the growth and function of connective tissue fibroblasts. In this article, we review the characteristics of lymphocyte and monocyte CK which appear to be involved in regulating fibroblast recruitment, proliferation, and matrix synthesis. Whereas these MNC products are important in normal physiologic wound healing, an imbalance of these CK may lead to pathophysiologic fibrosis and/or destruction of connective tissue components. Clinical states associated with MNC-mediated connective tissue pathology include scleroderma, rheumatoid arthritis, diffuse pulmonary idiopathic fibrosis, sarcoidosis and atherosclerosis. Characterization of the molecular pathways linking inflammatory mononuclear cells and fibrosis may provide avenues for therapeutic intervention.