Increased expression of interferon regulated and antiviral response genes in CD31+/CD102+ lung microvascular endothelial cells from systemic sclerosis patients with end-stage interstitial lung disease.

Abstract

Systemic sclerosis (SSc) is characterised by severe fibroproliferative vasculopathy, fibrosis in skin and multiple internal organs, and humoral, cellular and innate immunity abnormalities. Vascular alterations are the earliest and most severe SSc manifestations, however, the mechanisms responsible have remained elusive. To investigate the molecular abnormalities involved in SSc-vasculopathy we examined global gene expression differences between highly purified lung microvascular endothelial cells (MVECs) from patients with SSc-interstitial lung disease (SSc-ILD) and normal lung MVECs. MVECs were isolated from fresh transplanted lungs from patients with SSc-ILD. Sequential CD31 and CD102 immunopurification was performed to obtain highly purified CD31+/CD102+ lung MVECs. Global gene expression analysis was successfully performed in CD31+/CD102+ MVEC from two SSc-ILD patients and from two normal lungs. RT-PCR, Western blots, and indirect immunofluorescence validated the gene expression results. Numerous interferon-regulated genes (IRGs) including IFI44, IFI44L, IFI6, IFIH1, IFIT1, ISG-15, BST-2/Tetherin, and RSAD2/Viperin, genes encoding innate immunity antiviral responses (OAS1, OAS2, OAS3, OASL) and antiviral MX1 and MX2 proteins, and mesenchymal cell-specific genes were significantly overexpressed in CD31+/CD102+ SSc-ILD lung MVECs. Highly purified CD31+/CD102+ MVECs from lungs from SSc patients with end stage SSc-ILD displayed remarkable overexpression of numerous IRGs and of genes encoding antiviral innate immune response and antiviral proteins. These observations suggest that interferon-induced and antiviral response proteins may participate in the pathogenesis of SSc vasculopathy and SSc-ILD. The CD31+/CD102+ lung MVECs from SSc-ILD also showed elevated expression of mesenchymal cell-specific genes confirming the presence of endothelial to mesenchymal transition in SSc-ILD.