Vasculature in the Margin of the Psoriatic Lesion

Background: Factors initiating capillary conversion in the immunopathogenesis of psoriasis are not well established and quantification of vascular changes in- and outside visible psoriatic plaque has not been studied extensively. Objectives: To assess the pathological involvement of capillaries in the context of well-established features of psoriasis in different phases: symptomless psoriatic skin distant from a lesion (SDL), adjacent to a lesion (SAL), the margin zone of the lesion (ML) and the center of the psoriatic lesion (CL). Methods: In 10 patients with chronic plaque psoriasis, and 10 healthy matched controls, vascular parameters (vascular tonicity (VD), vascular surface area (VAR), microvascular density (MVD), angiogenesis (pEC)) and hypoxia in the context of well-established features (keratinocyte proliferation, neutrophils and T-cells) were analyzed within the psoriatic lesion and symptomless psoriatic skin, using immunohistochemical markers (Ki67/CD31 double-staining and HIF-1α-, Elastase- and T-Bet-staining). Results: VD and neutrophils were significantly increased in all sites, compared to healthy controls. The VAR, MVD, Ki67+ nuclei, HIF-1α and T-Bet start to augment in the SAL. Within the overt psoriatic plaque angiogenesis increases. Biopsies closer to the center of a plaque, exhibited increased values of the MVD, VAR, VD, Ki67+ nuclei, T-Bet+ Th1 cells and neutrophils. Conclusion: In SDL, vasodilatation and activation of the innate immune system (increased neutrophils) was detected. This could indicate that psoriasis is not restricted to lesional skin, but rather is a systemic disease. Closer to the psoriatic plaque, vascular and epithelial proliferation was observed, along with hypoxic cells and activation of the acquired immunity (augmented T-Bet cells).