The role of endothelial cell apoptosis in the effect of etanercept in psoriasis.

Abstract

Psoriasis is a chronic inflammatory skin disease associated with abnormal vascular expansion in the papillary dermis. Tumour necrosis factor (TNF)-α is a proinflammatory cytokine that can induce antiapoptotic proteins and endothelial cell activation factors in psoriasis. The present study investigated the effect of the anti-TNF-α agent etanercept on the expression of endothelial nuclear factor-κB (NF-κB), angiogenic vascular endothelial growth factor (VEGF), endothelial cell marker CD31, antiangiogenic factor thrombospondin-1 (TSP-1), and antiapoptotic factors Bcl-2 and Bcl-xL in psoriasis. Sixteen patients with moderate-to-severe psoriasis were included in the study and treated with etanercept 50 mg twice weekly subcutaneously for 12 weeks. Biopsies of lesional skin (baseline, weeks 3, 6 and 10) were obtained and immunohistochemically stained with antibodies for CD31, VEGF, TSP-1, NF-κB, Bcl-2 and Bcl-xL. Double immunofluorescence staining for VEGF and CD31 was evaluated with confocal laser microscopy. The terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labelling (TUNEL) assay was applied for apoptosis detection. Etanercept caused a statistically significant time-dependent reduction in the number of dermal blood vessels, the number of CD31+ cells and VEGF in psoriatic lesions, with induction of endothelial cell apoptosis and statistically significant upregulation of TSP-1 in psoriatic vessels. Immunohistochemical analysis showed significant reduction of NF-κB, Bcl-2 and Bcl-xL expression in endothelial cells during treatment. These changes were accompanied by a marked clinical response. The present findings suggest that treatment with etanercept induces apoptosis, reduces apoptosis-inhibiting factors in psoriatic endothelial cells, and decreases angiogenesis in psoriatic skin.