Emerging roles of peroxisome proliferator-activated receptor-β/δ in inflammation

Peroxisome proliferator-activated receptor (PPAR)-β/δ is a member of the PPAR nuclear hormone receptor family. The PPARs are a family of 3 ligand-activated transcription factors: PPARα (NR1C1), PPARβ/δ (NR1C2), and PPARγ (NR1C3). All the PPARs play important roles in the regulation of metabolic pathways, including those of lipid of biosynthesis and glucose metabolism, as well as in a variety of cell differentiation, proliferation, and apoptosis pathways. Recently, there has been a great deal of interest in the involvement of PPARs in the inflammatory processes. In particular, PPARα and PPARγ inhibit the activation of inflammatory gene expression and can negatively interfere with pro-inflammatory transcription factor signalling pathways in vascular and inflammatory cells. In contrast, the roles of PPARβ/δ regulating inflammation and immunity are only just emerging. This review will focus on these emerging roles of PPARβ/δ in regulating inflammatory processes.