Immune Cells in Cardiovascular Disease: Has the Time Arrived for New Targets in Human Hypertension?

Immune System and Microvascular Remodeling in Humans

Low-grade inflammatory processes and related oxidative stress may have a key role in the pathogenesis of hypertension and hypertension-mediated organ damage. Innate immune cells, such as neutrophils, dendritic cells, monocytes/macrophages, as well as unconventional T lymphocytes like γδ T cells contribute to hypertension and may trigger vascular inflammation. Adaptive immunity has been demonstrated to participate in elevation of blood pressure and in vascular and kidney injury. In particular, effector T lymphocytes (Th1, Th2, and Th17) may play a relevant role in promoting hypertension and microvascular remodeling, whereas T-regulatory lymphocytes may have a protective role. Effector cytokines produced by these immune cells lead to increased oxidative stress, endothelial dysfunction and contribute to target organ damage in hypertension. A possible role of immune cell subpopulations in the development and regression of microvascular remodeling has also been proposed in humans with hypertension. The present review summarizes the key immune mechanisms that may participate in the pathophysiology of hypertension-mediated inflammation and vascular remodeling; advances in this field may provide the basis for novel therapeutics for hypertension.

Decreased circulating T regulatory lymphocytes in obese patients undergoing bariatric surgery

OBJECTIVE

It has been previously demonstrated that T lymphocytes may be involved in the development of hypertension and microvascular remodeling, and that circulating T effector lymphocytes may be increased in hypertension. In particular, Th1 and Th 17 lymphocytes may contribute to the progression of hypertension and microvascular damage while T-regulatory (Treg) lymphocytes seem to be protective in this regard. However, no data is available about patients with severe obesity, in which pronounced microvascular alterations were observed.

DESIGN AND METHODS

We have investigated 32 severely obese patients undergoing bariatric surgery, as well as 24 normotensive lean subjects and 12 hypertensive lean subjects undergoing an elective surgical intervention. A peripheral blood sample was obtained before surgery for assessment of CD4+ T lymphocyte subpopulations. Lymphocyte phenotype was evaluated by flow cytometry in order to assess T-effector and Treg lymphocytes.

RESULTS

A marked reduction of several Treg subpopulations was observed in obese patients compared with controls, together with an increased in CD4+ effector memory T-effector cells.

CONCLUSION

In severely obese patients, Treg lymphocytes are clearly reduced and CD4+ effector memory cells are increased. It may be hypothesized that they might contribute to the development of marked microvascular alterations previously observed in these patients.

Role of Inflammatory Diseases in Hypertension

Chronic inflammatory diseases (CID) are characterized by an increased risk of cardiovascular (CV) morbidity and mortality. Several mechanisms, including early acceleration of subclinical atherosclerotic damage, inflammatory markers and immune system deregulation factors, have been demonstrated to strictly interplay for development and progression of atherosclerosis. Moreover, traditional CV risk factors are likely to explain at least some of the excess of CV risk in these patients. Among traditional CV risk factors, compelling evidence suggests a higher incidence and prevalence of hypertension in patients with CID in comparison to the general population. Moreover, hypertension represents an important predictor of CV events in these patients. Pathogenic mechanisms underlying the rise of blood pressure in CID are multifactorial and still poorly investigated. Indeed, multiple disease-related factors may affect blood pressure control in these patients and hypertension may affect disease prognosis and increase CV risk. Better knowledge of the complex interplay between hypertension and CID will be important to elucidate pathogenic mechanisms and to improve CV outcome in these patients. Aim of this review is to highlight available evidence on the relationship between hypertension and CID and to elucidate the multiple factors that may affect blood pressure control in these disorders.