PPARgamma--an important regulator of monocyte/macrophage function.

Regulation of monocyte/macrophage function is important in coordinating immune responses. Their contact with invading pathogens activates signaling pathways that provoke pro-inflammatory gene expression and thus causing a locally restricted inflammation. Recently, the peroxisome proliferator-activated receptor gamma (PPARgamma) has been identified to antagonize pro-inflammatory responses in monocytes/macrophages, causing an anti-inflammatory and/or desensitized phenotype to predominate. For PPARgamma, the general mechanisms facilitating the transition from a pro- to an anti-inflammatory phenotype have been elucidated. PPARgamma is a member of the nuclear receptor superfamily and is activated upon endogenous as well as exogenous agonist binding. Here we focus on its role in monocyte/macrophage biology in affecting inflammation. Summarizing current information, a model is proposed which gives rise to potential new therapeutic possibilities for the treatment of diseases presumably involving PPARgamma-dependent regulatory circuits.