Role of the Immune System in Hypertension (original) (raw)

Immune System and Inflammation in Hypertension

IntechOpen eBooks, 2022

Hypertension is a widely prevalent and a major modifiable risk factor for cardiovascular diseases. Despite the available long list of anti-hypertension drugs and lifestyle modification strategies for blood pressure control, a large number of hypertensive patients fail to achieve adequate blood pressure control even when prescribed a combination of drugs from three or more classes. Thus, identifying and targeting of further mechanisms that underlie hypertension is decisive in alleviating burden of this disorder. In recent decades research have shown that perturbed immune system and inflammation contribute to hypertension. Experimental studies on animal models have shown that immune cells such as dendritic cells, macrophages, and lymphocytes contribute for the development and/or sustaining of hypertension. In hypertension, inflammatory immune cells that infiltrated the kidney cause retention of sodium, renal fibrosis, glomerular injury, and chronic kidney disease, all of them contribute for elevated blood pressure. Similarly, immune cells and inflammatory cytokines are involved in blood vessels structural and functional changes associated with hypertension. Perturbed immune system and chronic low-grade systemic inflammation enhance SNS activity and this contributes to elevated blood pressure by its effect on blood vessels tone, on the kidneys, and on immune system.

The immune system in hypertension

AJP: Advances in Physiology Education, 2014

While hypertension has predominantly been attributed to perturbations of the vasculature, kidney, and central nervous system, research for almost 50 yr has shown that the immune system also contributes to this disease. Inflammatory cells accumulate in the kidneys and vasculature of humans and experimental animals with hypertension and likely contribute to end-organ damage. We and others have shown that mice lacking adaptive immune cells, including recombinase-activating gene-deficient mice and rats and mice with severe combined immunodeficiency have blunted hypertension to stimuli such as ANG II, high salt, and norepinephrine. Adoptive transfer of T cells restores the blood pressure response to these stimuli. Agonistic antibodies to the ANG II receptor, produced by B cells, contribute to hypertension in experimental models of preeclampsia. The central nervous system seems important in immune cell activation, because lesions in the anteroventral third ventricle block hypertension and...

Targeting the immune system to treat hypertension

Current Opinion in Nephrology and Hypertension, 2014

Purpose of review Research over the past decade has significantly deepened our understanding of mechanisms that drive the development of hypertension. In particular, a novel paradigm of inflammation as a common mediator of cardiovascular and kidney disease has emerged. This review will summarize the role of the immune system in cardiovascular disease, explore some of the most promising new therapeutic directions and consider their potential as new treatments for hypertension. Recent findings Recent data continue to demonstrate that targeting the immune system can prevent hypertension in a variety of experimental models. Tempering the enthusiasm for a long-awaited new approach to treating hypertension is decades of clinical data, showing that classic immunosuppression regimens are associated with significant side-effects-including cardiovascular disease-that effectively preclude their use in the setting of chronic hypertension. New, more specific therapies are being developed that target cytokines including IL-17, IL-6 and TNFa.

The immunology of hypertension

The Journal of experimental medicine, 2018

Although systemic hypertension affects a large proportion of the population, its etiology remains poorly defined. Emerging evidence supports the concept that immune cells become activated and enter target organs, including the vasculature and the kidney, in this disease. Mediators released by these cells, including reactive oxygen species, metalloproteinases, cytokines, and antibodies promote dysfunction of the target organs and cause damage. In vessels, these factors enhance constriction, remodeling, and rarefaction. In the kidney, these mediators increase expression and activation of sodium transporters, and cause interstitial fibrosis and glomerular injury. Factors common to hypertension, including oxidative stress, increased interstitial sodium, cytokine production, and inflammasome activation promote immune activation in hypertension. Recent data suggest that isolevuglandin-modified self-proteins in antigen-presenting cells are immunogenic, promoting cytokine production by the ...

The immune system and hypertension

Immunologic Research, 2014

A powerful interaction between the autonomic and the immune systems plays a prominent role in the initiation and maintenance of hypertension and significantly contributes to cardiovascular pathology, end-organ damage and mortality. Studies have shown consistent association between hypertension, proinflammatory cytokines and the cells of the innate and adaptive immune systems. The sympathetic nervous system, a major determinant of hypertension, innervates the bone marrow, spleen and peripheral lymphatic system and is proinflammatory, whereas the parasympathetic nerve activity dampens the inflammatory response through a7-nicotinic acetylcholine receptors. The neuro-immune synapse is bidirectional as cytokines may enhance the sympathetic activity through their central nervous system action that in turn increases the mobilization, migration and infiltration of immune cells in the end organs. Kidneys may be infiltrated by immune cells and mesangial cells that may originate in the bone marrow and release inflammatory cytokines that cause renal damage. Hypertension is also accompanied by infiltration of the adventitia and perivascular adipose tissue by inflammatory immune cells including macrophages. Increased cytokine production induces myogenic and structural changes in the resistance vessels, causing elevated blood pressure. Cardiac hypertrophy in hypertension may result from the mechanical afterload and the inflammatory response to resident or migratory immune cells. Toll-like receptors on innate immune cells function as sterile injury detectors and initiate the inflammatory pathway. Finally, abnormalities of innate immune cells and the molecular determinants of their activation that include toll-like receptor, adrenergic, cholinergic and AT1 receptors can define the severity of inflammation in hypertension. These receptors are putative therapeutic targets.

Innate Immune Response in Hypertension

Current Pharmaceutical Design

: Even though an association between inflammation and hypertension has been known for many years, it has not been simple to ascertain the role of several physiological responses involved. The innate immune response plays a critical role in these physiological responses. Innate immune cells can be activated directly by shear stress, activate the inflammasome and produce numerous cytokines and soluble mediators essential in hypertension. NFkB activation is mainly involved in the activation of innate immune cells. Shear stress also stimulates the expression of DAMP and PAMP receptors, enhancing pathogen and danger signals and magnifying inflammation. The adaptative immune response is activated with the increased antigen presentation resulting from the insults mentioned. Chronic inflammation may lead to autoimmunity. Peripheral hypoxia, a consequence of hypertension, activates hypoxia-inducing factors 1-α and 1-β (HIF-1α, HIF-1β), which modulate innate immune cells and promote inflammation. HIF-1α is involved in the upregulation of oxygen and nitrogen radical production proteins. HIF-1β down-regulates antioxidant enzymes. However, the critical evidence of the role of innate immune cells in hypertension came from the results of clinical trials involving therapies blocking inflammatory cytokines and Toll-like receptor expression. Several lines of research have been conducted on this complex disease. Pro-tolerogenic innate immune cells, myeloid suppressor cells, and M2 macrophages may play a crucial role in promoting or resolving inflammation, cardiovascular diseases and hypertension, and should be studied in detail.

The link between immunity and hypertension in the kidney and heart

Frontiers in Cardiovascular Medicine

Hypertension is the primary cause of cardiovascular disease, which is a leading killer worldwide. Despite the prevalence of this non-communicable disease, still between 90% and 95% of cases are of unknown or multivariate cause (“essential hypertension”). Current therapeutic options focus primarily on lowering blood pressure through decreasing peripheral resistance or reducing fluid volume, but fewer than half of hypertensive patients can reach blood pressure control. Hence, identifying unknown mechanisms causing essential hypertension and designing new treatment accordingly are critically needed for improving public health. In recent years, the immune system has been increasingly implicated in contributing to a plethora of cardiovascular diseases. Many studies have demonstrated the critical role of the immune system in the pathogenesis of hypertension, particularly through pro-inflammatory mechanisms within the kidney and heart, which, eventually, drive a myriad of renal and cardiov...

Vascular Inflammatory Cells in Hypertension

Frontiers in Physiology, 2012

Hypertension is a common disorder with uncertain etiology. In the last several years, it has become evident that components of both the innate and adaptive immune system play an essential role in hypertension. Macrophages and T cells accumulate in the perivascular fat, the heart and the kidney of hypertensive patients, and in animals with experimental hypertension. Various immunosuppressive agents lower blood pressure and prevent endorgan damage. Mice lacking lymphocytes are protected against hypertension, and adoptive transfer of T cells, but not B cells in the animals restores their blood pressure response to stimuli such as angiotensin II or high salt. Recent studies have shown that mice lacking macrophages have blunted hypertension in response to angiotensin II and that genetic deletion of macrophages markedly reduces experimental hypertension. Dendritic cells have also been implicated in this disease. Many hypertensive stimuli have triggering effects on the central nervous system and signals arising from the circumventricular organ seem to promote inflammation. Studies have suggested that central signals activate macrophages and T cells, which home to the kidney and vasculature and release cytokines, including IL-6 and IL-17, which in turn cause renal and vascular dysfunction and lead to blood pressure elevation. These recent discoveries provide a new understanding of hypertension and provide novel therapeutic opportunities for treatment of this serious disease.

Sympathetic-mediated activationversussuppression of the immune system: consequences for hypertension

The Journal of Physiology, 2015

It is generally well-accepted that the immune system is a significant contributor in the pathogenesis of hypertension. Specifically, activated and pro-inflammatory T-lymphocytes located primarily in the vasculature and kidneys appear to have a causal role in exacerbating elevated blood pressure. It has been proposed that increased sympathetic nerve activity and noradrenaline outflow associated with hypertension may be primary contributors to the initial activation of the immune system early in the disease progression. However, it has been repeatedly demonstrated in many different human and experimental diseases that sympathoexcitation is immunosuppressive in nature. Moreover, human hypertensive patients have demonstrated increased susceptibility to secondary immune insults like infections. Thus, it is plausible, and perhaps even likely, that in diseases like hypertension, specific immune cells are activated by increased noradrenaline, while others are in fact suppressed. We propose a model in which this differential regulation is based upon activation status of the immune cell as well as the resident organ. With this, the concept of global immunosuppression is obfuscated as a viable target for hypertension treatment, and we put forth the concept of focused organ-specific immunotherapy as an alternative option.