Inositoylated Platelet-Activating Factor (Ino-C2-PAF) Modulates Dynamic Lymphocyte-Endothelial Cell Interactions and Alleviates Psoriasis-Like Skin Inflammation in Two Complementary Mouse Models

Psoriasis, a tumor necrosis factor alpha (TNF alpha)-governed inflammatory disorder with prominent dysregulation of cutaneous vascular functions, has evolved into a model disorder for studying anti-inflammatory therapies. We present experimental in vitro and in vivo data on 1-O-octadecyl-2-O-(2-(myo-inositolyl)-ethyl)-sn-glycero-3-(R/S)-phosphatidyl-choline (Ino-C2-PAF), the lead compound of a class of synthetic glycosylated phospholipids, in anti-inflammatory therapy. Ino-C2-PAF strongly induced apoptosis only in TNF alpha-stimulated, but not in untreated human vascular endothelial cells. Moreover, TNF alpha-induced endothelial adhesion molecules that mediated the rolling and firm adhesion of leukocytes (vascular cell adhesion protein-1 (VCAM-1), E-selectin, and ICAM-1) were selectively downregulated by Ino-C2-PAF. Similarly, expression of L-selectin, VCAM-1 receptor alpha(4)beta(1) integrin, and lymphocyte function-associated antigen-1 on human peripheral blood mononuclear cells was reduced without induction of apoptosis. Functionally, these changes were accompanied by significant impairment of rolling and adhesion of human peripheral blood lymphocytes on TNF alpha-activated endothelial cells in a dynamic flow chamber system. When the therapeutic potential of Ino-C2-PAF was assessed in two complementary mouse models of psoriasis, K5.hTGF beta 1 transgenic and JunB/c-Jun-deficient mice, Ino-C2-PAF led to significant alleviation of the clinical symptoms and normalized the pathological cutaneous changes including vascularization. There were no overt adverse effects. These findings suggested that Ino-C2-PAF is a potential candidate in the therapy of inflammatory skin diseases that include abnormal vascular functions.