Lysophosphatidylcholine increases expression of heparin-binding epidermal growth factor-like growth factor in human T lymphocytes.

Abstract

Atherosclerotic lesions contain substantial numbers of activated T lymphocytes in addition to monocytes/macrophages. T cell-derived cytokines and growth factors may play a role in atherogenesis; however, stimuli responsible for T-cell activation in atherogenesis have not been fully elucidated. In this study, we provide evidence that lysophosphatidylcholine (lyso-PC), a polar phospholipid component increased in atherogenic lipoproteins and atherosclerotic lesions, can upregulate gene expression and secretion of heparin-binding epidermal growth factor-like growth factor (HB-EGF) in cultured T lymphocytes isolated from human peripheral blood. Effects of lyso-PC on T lymphocytes appear to be selective and specific, since lyso-PC also increases interleukin (IL)-2 receptor expression but does not affect mRNA levels for IL-2 or IL-4. Lyso-PC-induced upregulation of HB-EGF and IL-2 receptor mRNA in peripheral T cells is mostly dependent on exogenous IL-2 in conditioned medium. The effect of lyso-PC on HB-EGF induction was more potent in CD4+ cells than in CD8+ cells, although lyso-PC increases IL-2 receptor expression dramatically in both CD4+ cells and CD8+ cells. Lyso-PC similarly increased HB-EGF expression in Jurkat cells, a cell line for human CD4+ T lymphocytes. These results in vitro suggest that lyso-PC may be an important stimulus for T cells in atherogenesis in vivo to upregulate HB-EGF and that T cell-derived smooth muscle growth factors may modulate atherosclerotic progression.