Variations in the genes encoding the peroxisome proliferator-activated receptors alpha and gamma in psoriasis

The three peroxisome proliferator-activated receptor (PPAR) subtypes alpha, delta (beta), and gamma belong to the group of nuclear receptors that act as ligand-activated transcription factors. Recently, expression of PPARalpha and gamma in keratinocytes has been demonstrated, and ligands of PPARalpha and gamma have been found to enhance epidermal maturation and protect against cutaneous inflammation. There is evidence for a possible role of PPARs in psoriasis, as the expression of PPARalpha and gamma is decreased in lesional skin and treatment with PPARgamma agonists improves psoriatic keratinocyte pathology in vitro and in vivo. We performed a case-control study to search for possible associations between variations in the genes encoding PPARalpha and gamma and psoriasis. Seven variations in these genes were analyzed in 192 patients with chronic plaque-type psoriasis and 330 healthy controls by PCR-based methods. No association between any of the investigated PPAR variants and psoriasis was found. Our findings argue against a significant contribution of the investigated PPAR variations to the genetic basis of psoriasis.