The role of the Peroxisome Proliferators Activated Receptors alpha (PPAR-a) in the regulation of acute inflammation

The peroxisome proliferator-activated receptor-α (PPAR- α) is a member of the nuclear receptor superfamily of ligand-dependent transcription factors related to retinoid, steroid, and thyroid hormone receptors. The aim of the present study was to evaluate the role of the PPAR- α receptor on the development of acute inflammation. To address this question, we used two animal models of acute inflammation (carrageenan-induced paw edema and carrageenan-induced pleurisy). We report here that when compared with PPAR- α wild-type mice, PPAR- α knockout mice (PPAR- α KO) mice experienced a higher rate of the extent and severity when subjected to carrageenan injection in the paw edema model or to carrageenan administration in the pleurisy model. In particular, the absence of a functional PPAR- α gene in PPAR- α KO mice resulted in a significant augmentation of various inflammatory parameters (e.g., enhancement of paw edema, pleural exudate formation, mononuclear cell infiltration, and histological injury) in vivo. Furthermore, the absence of a functional PPAR- α gene enhanced the staining (immunohistochemistry) for FAS ligand in the paw and in the lung and the expression of tumor necrosis factor α and interleukin-1β in the lungs of carrageenan- treated mice. In conclusion, the increased inflammatory response observed in PPAR- αKO mice strongly suggests that a PPAR- α pathway modulates the degree of acute inflammation in the mice.