Immune mechanisms in hypertension and vascular injury.

Over the last 20 years it has become recognized that low-grade inflammation plays a role in cardiovascular disease. More recently, participation of the innate and the adaptive immune response in mechanisms that contribute to inflammation in cardiovascular disease has been reported in atherosclerosis and hypertension. Different subsets of lymphocytes and their cytokines are involved in vascular remodelling in hypertension, chronic kidney disease and heart disease. Effector T-cells include Th1 (interferon-γ-producing) and Th2 (interleukin-4 producing) lymphocytes, as well as Th17 (which produce interleukin-17) and T-suppressor lymphocytes such as T(reg)-cells (regulatory T-cells), which express the transcription factor Foxp3 (forkhead box P3) and participate respectively as pro- and anti-inflammatory cells. Pro-inflammatory T-lymphocytes participate in mechanisms of cardiovascular disease in part by mediating the effects of angiotensin II and mineralocorticoids. Involvement of immune mechanisms in cardiac, vascular and renal changes in hypertension has been demonstrated in many experimental models, an example being the Dahl-salt sensitive rat and the spontaneously hypertensive rat. How activation of immunity is triggered remains unknown, but neo-antigens could be generated by elevated blood pressure through damage-associated molecular pattern receptors or other mechanisms. Once activated, Th1 cells may contribute to blood pressure elevation by affecting the kidney, vascular remodelling of blood vessels directly via the effects of the cytokines produced or through their effects on perivascular fat. T(reg)-cells protect from blood pressure elevation by acting upon similar targets. Recent data suggests that participation of these mechanisms that have been demonstrated already in murine models also occurs in humans. These novel findings may open the way for new therapeutic approaches to improve outcomes in hypertension and cardiovascular disease in humans.