Peroxisome proliferator‐activated receptor‐ β / δ modulates mast cell phenotype

Summary The peroxisome proliferator‐activated receptor‐ β / δ ( PPAR β / δ ) is known to have multiple anti‐inflammatory effects, typically observed in endothelial cells, macrophages, T cells and B cells. Despite the fact that mast cells are important mediators of inflammation, to date, the role of PPAR β / δ in mast cells has not been examined. Hence, the present study examined the hypothesis that PPAR β / δ modulates mast cell phenotype. Bone‐marrow‐derived mast cells ( BMMC s) and peritoneal mast cells from Pparβ/δ +/+ mice expressed higher levels of high‐affinity IgE receptor (Fc ε RI ) compared with Pparβ/δ −/− mice. BMMC s from Pparβ/δ +/+ mice also exhibited dense granules, associated with higher expression of enzymes and proteases compared with Pparβ/δ −/− mice. Resting BMMC s from Pparβ/δ +/+ mice secreted lower levels of inflammatory cytokines, associated with the altered activation of phospholipase C γ 1 and extracellular signal‐regulated kinases compared with Pparβ/δ −/− mice. Moreover, the production of cytokines by mast cells induced by various stimuli was highly dependent on PPAR β / δ expression. This study demonstrates that PPAR β / δ is an important regulator of mast cell phenotype.