Dissecting the Cellular Mechanism of Prostacyclin Analog Iloprost in Reversing Vascular Dysfunction in Scleroderma

Abstract

Objective. Intravenous iloprost improves Raynaud's phenomenon (RP) and promotes healing of digital ulcers in systemic sclerosis (SSc; scleroderma). Despite a short half-life, its clinical efficacy lasts weeks. Endothelial adherens junctions, which are formed by VE-cadherin clustering between endothelial cells (ECs), regulate endothelial properties including barrier function, endothelial-to-mesenchymal transition (EndoMT), and angiogenesis. We undertook this study to investigate the hypothesis that junctional disruption contributes to vascular dysfunction in SSc, and that the protective effect of iloprost is mediated by strengthening of those junctions. Methods. Dermal ECs from SSc patients and healthy controls were isolated. The effect of iloprost on ECs was examined using immunofluorescence, permeability assays, Matrigel tube formation, and quantitative polymerase chain reaction. Results. Adherens junctions in SSc were disrupted compared to normal ECs, as indicated by reduced levels of VE-cadherin and increased permeability in SSc ECs (P < 0.05). Iloprost increased VE-cadherin clustering at junctions and restored junctional levels of VE-cadherin in SSc ECs (mean ± SD 37.3 ± 4.3 fluorescence units) compared to normal ECs (mean ± SD 29.7 ± 3.4 fluorescence units; P < 0.05), after 2 hours of iloprost incubation. In addition, iloprost reduced permeability of monolayers, increased tubulogenesis, and blocked EndoMT in both normal and SSc ECs (n ≥ 3; P < 0.05). The effects in normal ECs were inhibited by a function-blocking antibody that prevents junctional clustering of VE-cadherin. Conclusion. Our data suggest that the long-lasting effects of iloprost reflect its ability to stabilize adherens junctions, resulting in increased tubulogenesis and barrier function and reduced EndoMT. These findings provide a mechanistic basis for the use of iloprost in treating SSc patients with RP and digital ulcers.

Genome‐Wide Reduction in Chromatin Accessibility and Unique Transcription Factor Footprints in Endothelial Cells and Fibroblasts in Scleroderma Skin

“…It has been shown that production of NO is impaired in SSc ECs due to down-regulation of endothelial NO synthase (15). These cells also exhibit a mesenchymal phenotype with enhanced endothelial-to-mesenchymal transition that leads to higher ECM expression (16,17). Although the role of cilia in fibrosis has been implicated in SSc (18), their involvement in EC function has not been examined.…”

New Insights into Profibrotic Myofibroblast Formation in Systemic Sclerosis: When the Vascular Wall Becomes the Enemy

“…The synthetic retinoid tamibarotene (Am80) has been reported to significantly attenuate dermal/hypodermal fibrosis and EndoMT in bleomycin-treated mice [ 207 ], while the synthetic analogue of prostacyclin iloprost was able to promote angiogenesis and prevent EndoMT in SSc microvascular ECs [ 208 ].…”

Iloprost Attenuates Oxidative Stress-Dependent Activation of Collagen Synthesis Induced by Sera from Scleroderma Patients in Human Pulmonary Microvascular Endothelial Cells

“…In the same way, SSs sera-induced activation of collagen synthesis, which prominently occurs in the first hour, resulted significantly higher than that induced by HD sera ( Figure 1 E). Iloprost’s vasculoprotective properties have been also reported in a recent paper showing its ability to preserve vascular function by stabilizing endothelial adherens junctions, increasing tubulogenesis and barrier function, ultimately reducing ECs shift toward collagen-producing/αSMA-positive cells [ 32 ]. In agreement with these data, our current findings report the ability of Iloprost to counteract both ECs damage ( Figure 1 C–F) and collagen synthesis ( Figure 1 E) elicited by sera of SSc patients.…”