Abstract 550: Differential Regulation of CD39 Expression by Il-1ß in Leukocytes and Endothelial Cells

Background CD39 (ENTPD-1) is a membrane-spanning ectonucleotidase that is responsible for the phosphohydrolysis of ATP to ADP and ADP to AMP. CD39 levels are modulated in multiple conditions, including pulmonary hypertension, cardiac, liver and renal injury, cancer, and autoimmune diseases. However, little is known about the upstream regulation of this molecule, or whether modulation of CD39 represents a response to inflammatory cytokines or is integral to the pathological process. Elevated levels of cytokine IL-1β are a hallmark of many inflammatory states. Objectives Objectives were to measure CD39 expression after stimulation with the IL-1β. CD39 is expressed on leukocytes and endothelial cells; therefore, CD39 expression was evaluated in these cell types. Methods Human umbilical vein endothelial cells (HUVECs) were treated with either 10 pg/ml or 1 ng/ml IL-1β for 12 hours. Cells were harvested and CD39 mRNA expression was measured using qPCR. CD39 protein expression was measured using Western Blot. Mononuclear leukocytes were isolated from whole blood of healthy humans via density gradient cell separation (n=3). Leukocytes were cultured for 12 hours with or without the addition of IL-1β (1ng/ml). Leukocytes were then assessed for expression of CD39, CD73, CD14, CD19, CD4, CD8, and CD25 by flow cytometry. Findings IL-1β (1 ng/ml) treatment resulted in decreased CD39 mRNA expression in HUVECs (1.1 vs. 3.9, p Conclusions This is the first report of modulation of CD39 expression in response to the inflammatory cytokine IL-1β. Interestingly, IL-1β downregulated CD39 expression in HUVECs, but resulted in increased CD39 expression on a T-reg population positive for CD4 and CD25. CD39 could be differentially regulated depending on the inflammatory stimulus and target cell type.