The role of pigment epithelium-derived factor as an adipokine in psoriasis

Pigment epithelium-derived factor (PEDF), first purified from the conditioned medium of human retinal pigment epithelial cells, has been shown to be a highly effective inhibitor of angiogenesis. A recent study showed that PEDF is also a novel adipokine secreted mainly by adipocytes. Psoriasis has been shown to be associated with metabolic syndrome (MS) and some adipokines. Since PEDF levels were reported to be elevated in the serum of patients with MS, we examined PEDF levels in the serum of psoriasis patients and studied the relationships between PEDF levels and other cytokines. Circulating levels of PEDF were significantly elevated in the sera of psoriasis patients compared to normal controls. PEDF levels were highly negatively associated with TNF-α levels in normal controls. Furthermore, the association between PEDF and TNF-α had a negative correlation in psoriasis patients although not statistically significant. These data suggest that PEDF may be elevated as an anti-inflammatory system in patients with psoriasis.