A Novel Mechanism of γ/δ T-Lymphocyte and Endothelial Activation by Shear Stress The Role of Ecto-ATP Synthase β Chain

Rationale: Endothelial cells (ECs) have distinct mechanotransduction mechanisms responding to laminar versus disturbed flow patterns. Endothelial dysfunction, affected by imposed flow, is one of the earliest events leading to atherogenesis. The involvement of gamma/delta T lymphocytes in endothelial dysfunction under flow is largely unknown. Objective: To investigate whether shear stress regulates membrane translocation of ATP synthase beta chain (ATPS beta) in ECs, leading to the increased gamma/delta T-lymphocyte adhesion and the related functions. Method and Results: We applied different flow patterns to cultured ECs. Laminar flow decreased the level of membrane-bound ATPS beta (ecto-ATPS beta) and depleted membrane cholesterol, whereas oscillatory flow increased the level of ecto-ATPS beta and membrane cholesterol. Incubating ECs with cholesterol or depleting cellular cholesterol with beta-cyclodextrin mimicked the effect of oscillatory or laminar flow, respectively. Knockdown caveolin-1 by small interfering RNA prevented ATPS beta translocation in response to laminar flow. Importantly, oscillatory flow or cholesterol treatment elevated the number of gamma/delta T cells binding to ECs, which was blocked by anti-ATPS beta antibody. Furthermore, the incubation of gamma/delta T cells with ECs increased tumor necrosis fact alpha and interferon-gamma secretion from T cells and vascular cell adhesion molecule-1 expression in ECs. In vivo, gamma/delta T-cell adhesion and ATPS beta membrane translocation was elevated in the aortic inner curvature and disturbed flow areas in partially ligated carotid arteries of ApoE(-/-) mice fed a high-fat diet. Conclusions: This study provides evidence that disturbed flow and hypercholesterolemia synergistically promote gamma/delta T-lymphocyte activation by the membrane translocation of ATPS beta in ECs and in vivo in mice, which is a novel mechanism of endothelial activation. (Circ Res. 2011;108:410-417.)