Variations in the genes encoding the peroxisome proliferator-activated receptors α and γ in psoriasis

The three peroxisome proliferator-activated receptor (PPAR) subtypes α, δ (β), and γ belong to the group of nuclear receptors that act as ligand-activated transcription factors. Recently, expression of PPARα and γ in keratinocytes has been demonstrated, and ligands of PPARα and γ 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 PPARα and γ is decreased in lesional skin and treatment with PPARγ 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 PPARα and γ 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.