Persistent and selective upregulation of renin–angiotensin system in circulating T lymphocytes in unstable angina

Abstract

Introduction: Unstable angina is associated with an acute systemic inflammatory reaction and circulating T lymphocytes are activated. We investigated whether in unstable angina with marked immune system activation a selective upregulation of the circulating T-cell renin–angiotensin system, modulated by angiotensin II, could occur. Methods: We studied 13 unstable angina patients, 10 patients with stable angina and 10 healthy subjects. After T-lymphocyte isolation, mRNAs for angiotensin-converting enzyme (ACE) and angiotensin type 1 receptor (AT1-R) were quantified at baseline and after angiotensin II stimulation. ACE activity in cell pellet and supernatant and angiotensin II cell content were measured. Results: Plasma renin activity was similar in controls, stable and unstable angina patients. At baseline ACE and AT1-R mRNA levels were higher (P<0.05) in T cells from unstable angina patients than in T cells from stable angina patients and controls, and further increased after angiotensin II addition to cultured T cells. ACE activity of unstable angina T cells was significantly higher than that of T cells from controls and stable angina patients. Only in T cells from unstable angina patients did angiotensin II stimulation cause the almost complete release of ACE activity in the supernatant. Conclusions: The circulating T-cell-based renin–angiotensin system from unstable angina patients was selectively upregulated. In vivo unstable angina T cells could locally increase angiotensin II concentration in tissues where they migrate independently of the circulating renin–angiotensin system.