Coronary Vasodilation Mediated by T Cells Expressing Choline Acetyltransferase

CD4(+) T cells expressing choline acetyltransferase (ChAT) have recently been shown to cause a drop in systemic blood pressure when infused into mice. The aim of this study was to determine if ChAT-expressing T cells could regulate coronary vascular reactivity. Preconstricted segments of epicardial and intramyocardial porcine coronary arteries relaxed in response to Jurkat T cells (JT) that overexpressed ChAT (JT(ChAT) cells). The efficacy of the JT(ChAT) cells was similar in epicardial and intramyocardial vessels with a maximum dilator response to 3 x 10(5) cells/mL of 38.0 +/- 6.7% and 38.7 +/- 7.25%, respectively. In contrast, nontransfected JT cells elicited a weak dilator response, followed by a weak contraction. The response of JT(ChAT) cells was dependent on the presence of the endothelial cells. In addition, the response could be significantly reduced by W-nitro-L-arginine methyl ester (L-NAME) and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) in the presence of indomethacin. JT(ChAT )cells, but not JT cells, increased the expression of phosphorylated endothelial nitric oxide synthase (eNOS). JT(ChAT )cells contained significantly greater levels of acetylcholine compared with JT cells; however, the nonselective muscarinic antagonist atropine and the M-1 receptor antagonist pirenzepine both failed to block the dilator effect of JT(ChAT )cells. Exogenously added acetylcholine induced only a weak relaxation (similar to 10%) at low concentrations, which became a contractile response at higher concentrations. These data illustrate the capacity for cells that express ChAT to regulate coronary vascular reactivity, via mechanisms that are dependent on interaction with the endothelium and in part mediated by the release of nitric oxide. NEW & NOTEWORTHY This study shows ChAT-expressing T cells can induce vasodilation of the blood vessel in the coronary circulation and that this effect relies on a direct interaction between T cells and the coronary vascular endothelium. The study establishes a potential immunomodulatory role for T cells in the coronary circulation. The present findings offer an additional possibility that a deficiency of ChAT-expressing T cells could contribute to reduced coronary blood flow and ischemic events in the myocardium.