Abstract 5656: Anticentromere Antibody Increases ICAM-1 Expression and Monocyte Adhesion in Pulmonary Endothelial Cells: Implications for Scleroderma-Associated Pulmonary Hypertension

Abstract

BACKGROUND: Scleroderma is characterized by the presence of high circulating levels of anticentromere antibody (ACA) and is commonly complicated by pulmonary hypertension (PHT). We hypothesized that ACA may alter pulmonary endothelial cell function. METHODS: Human pulmonary microvascular endothelial cells (HPMvECs) were treated with ACA (0.25 – 1.0 mg/mL, equivalent to serum titers of 1:320 – 1:2560) and IgG controls. Monocyte adhesion to HPMvECs was measured by automated cell count and cell adhesion molecule expression (ICAM-1 and VCAM-1) was assessed by flow cytometry (protein) and RT-PCR (mRNA). Promoter activity was assessed by luciferase reporter vector in HPMvECs and human umbilical vein endothelial cells (HUVECs). ACA uptake into HPMvECs was assessed by fluorescent microscopy. RESULTS: Fluorescently labeled ACA was shown to penetrate HPMvECs within 10 min. ACA increased ICAM-1 protein levels in a dose-dependent manner (118±11, 132±8 & 162±7% increase vs control (100%) for 0.50, 0.75 & 1.0 mg/mL respectively, P < 0.0001, n=5; Fig ). No effect was observed for VCAM-1. ICAM-1 increases were associated with enhanced monocyte adhesion to endothelial cells (211±9%, 1.0 mg/mL vs control, P < 0.0001, n=3). ICAM-1 mRNA levels were markedly increased by ACA (745±113%, 1.0 mg/mL vs control, P < 0.0001, n=4). ACA did not affect ICAM-1 mRNA stability but increased ICAM-1 promoter activity (136±9% & 148±12%, 1.0 mg/mL vs control for HPMvECs & HUVECs respectively, P < 0.01, n=3). CONCLUSION: ACA increases HPMvECs ICAM-1 expression and monocyte cell adhesion. These findings may implicate a role for ACA in the development of PHT in scleroderma.