Expression of the Alpha, Beta, and Gamma Subunits of the Interleukin-2 Receptor by Human Vascular Smooth Muscle Cells

Interleukin 2 (IL-2) is a member of the cytokine family and contributes to the proliferation, survival, and death of lymphocytes [1]. The interleukin-2 receptor (IL-2) is a tripartite receptor commonly expressed on the surfaces of many lymphoid cells and is composed of three non-covalently associated subunits, alpha (CD25), beta (CD122), and gamma (CD132) [2]. Our laboratory has previously described IL-2 receptor Beta expression by vasculature smooth muscle cells (VSMC) in mice and humans [3]. The current work expands our previous observations by assessing the expression of the alpha and gamma subunits of the IL-2R by VSMCs. Analysis of IL-2R expression in human VSMCs revealed no detectable expression of the gamma subunit and low expression of the alpha subunit. Treatment of VSMCs with IL-2 induced VSMC proliferation with a concomitant increase in the expression of the gamma subunit while having no detectable effect on expression of the alpha or beta subunits. Treatment of VSMCs with LPS decreased expression of the beta subunits and had little effect on alpha or gamma expression. Understanding the mechanisms that regulate expression of the IL-2R by VSMCs and how binding of this receptor by IL-2 mediates VSMC proliferation will provide a better understanding of vascular biology and possible mechanisms underlying vascular diseases such as atherosclerosis