DC isoketal-modified proteins activate T cells and promote hypertension

In vitro safety pharmacology evaluation of 2-hydroxybenzylamine acetate

2-hydroxybenzylamine (2-HOBA), a compound found in buckwheat, is a potent scavenger of reactive γ-ketoaldehydes, which are increased in diseases associated with inflammation and oxidative stress. While the potential of 2-HOBA is promising, studies were needed to characterize the safety of the compound before clinical trials. In a series of experiments, the risks of 2-HOBA-mediated mutagenicity and cardio-toxicity were assessed in vitro. The effects of 2-HOBA on the mRNA expression of select cytochrome P450 (CYP) enzymes were also assessed in cryopreserved human hepatocytes. Further, the distribution and metabolism of 2-HOBA in blood were determined. Our results indicate that 2-HOBA is not cytotoxic or mutagenic in vitro and does not induce the expression of CYP1A2, CYP2B6, or CYP3A4 in human hepatocytes. The results of the hERG testing showed a low risk of cardiac QT wave prolongation. Plasma protein binding and red blood cell distribution characteristics indicate low protein binding and no preferential distribution into erythrocytes. The major metabolites identified were salicylic acid and the glycoside conjugate of 2-HOBA. Together, these findings support development of 2-HOBA as a nutritional supplement and provide important information for the design of further preclinical safety studies in animals as well as for human clinical trials with 2-HOBA.

A proposed mechanism for the Berecek phenomenon with implications for cardiovascular reprogramming

Berecek et al reported in the 1990s that when spontaneously hypertensive rat (SHR) mating pairs were treated with captopril and the resulting pups were continued on the drug for 2 months followed by drug discontinuation, the pups did not develop full blown hypertension, and the cardiovascular structural changes associated with hypertension in SHR were mitigated. The offspring of the pups also displayed diminished hypertension and structural changes, suggesting that the drug therapy produced a heritable amelioration of the SHR phenotype. This observation is reviewed. The link between cellular renin angiotensin systems and epigenetic histone modification is explored, and a mechanism responsible for the observation is proposed. In any case, the observations of Berecek are sufficiently intriguing and biologically important to merit re-exploration and definitive explanation. Equally important is determining the role of renin angiotensin systems in epigenetic modification.

The chemokine receptor CX3CR1 reduces renal injury in mice with angiotensin II-induced hypertension

The role of CX₃CR1, also known as fractalkine receptor, in hypertension is unknown. The present study determined the role of the fractalkine receptor CX₃CR1 in hypertensive renal and cardiac injury. Expression of CX₃CR1 was determined using CX₃CR1^GFP/+ mice that express a green fluorescent protein (GFP) reporter in CX₃CR1⁺ cells. FACS analysis of leukocytes isolated from the kidney showed that 34% of CD45⁺ cells expressed CX₃CR1. Dendritic cells were the majority of positive cells (67%) followed by macrophages (10%), NK cells (6%), and T cells (10%). With the use of confocal microscopy, the receptor was detected in the kidney only on infiltrating cells but not on resident renal cells. To evaluate the role of CX₃CR1 in hypertensive end-organ injury, an aggravated model of hypertension was used. Unilateral nephrectomy was performed followed by infusion of angiotensin II (ANG II, 1.5 ng·g^-1·min^-1) and a high-salt diet in wild-type ( n = 15) and CX₃CR1-deficient mice ( n = 18). CX₃CR1 deficiency reduced the number of renal dendritic cells and increased the numbers of renal CD11b/F4/80⁺ macrophages and CD11b/Ly6G⁺ neutrophils in ANG II-infused mice. Surprisingly, CX₃CR1-deficient mice exhibited increased albuminuria, glomerular injury, and reduced podocyte density in spite of similar levels of arterial hypertension. In contrast, cardiac damage as assessed by increased heart weight, cardiac fibrosis, and expression of fetal genes, and matrix components were not different between both genotypes. Our findings suggest that CX₃CR1 exerts protective properties by modulating the invasion of inflammatory cells in hypertensive renal injury. CX₃CR1 inhibition should be avoided in hypertension because it may promote hypertensive renal injury.

Hypertension: Focus on autoimmunity and oxidative stress

Understanding the causal role of the immune and inflammatory responses in hypertension has led to questions regarding the links between hypertension and autoimmunity. Immune pathology in primary hypertension mimics several autoimmune mechanisms observed in the pathogenesis of systemic lupus erythematosus, psoriasis, systemic sclerosis, rheumatoid arthritis and periodontitis. More importantly, the prevalence of hypertension in patients with these autoimmune diseases is significantly increased, when compared to control populations. Clinical and epidemiological evidence is reviewed along with possible mechanisms linking hypertension and autoimmunity. Inflammation and oxidative stress are linked in a self-perpetuating cycle that significantly contributes to the vascular dysfunction and renal damage associated with hypertension. T cell, B cell, macrophage and NK cell infiltration into these organs is essential for this pathology. Effector cytokines such as IFN-γ, TNF-α and IL-17 affect Na⁺/H⁺ exchangers in the kidney. In blood vessels, they lead to endothelial dysfunction and loss of nitric oxide bioavailability and cause vasoconstriction. Both renal and vascular effects are, in part, mediated through induction of reactive oxygen species-producing enzymes such as superoxide anion generating NADPH oxidases and dysfunction of anti-oxidant systems. These mechanisms have recently become important therapeutic targets of novel therapies focused on scavenging oxidative (isolevuglandin) modification of neo-antigenic peptides. Effects of classical immune targeted therapies focused on immunosuppression and anti-cytokine treatments are also reviewed.

Hypertension and increased endothelial mechanical stretch promote monocyte differentiation and activation: roles of STAT3, interleukin 6 and hydrogen peroxide

Aims

Monocytes play an important role in hypertension. Circulating monocytes in humans exist as classical, intermediate, and non-classical forms. Monocyte differentiation can be influenced by the endothelium, which in turn is activated in hypertension by mechanical stretch. We sought to examine the role of increased endothelial stretch and hypertension on monocyte phenotype and function.

Methods and results

Human monocytes were cultured with confluent human aortic endothelial cells undergoing either 5% or 10% cyclical stretch. We also characterized circulating monocytes in normotensive and hypertensive humans. In addition, we quantified accumulation of activated monocytes and monocyte-derived cells in aortas and kidneys of mice with Angiotensin II-induced hypertension. Increased endothelial stretch enhanced monocyte conversion to CD14++CD16+ intermediate monocytes and monocytes bearing the CD209 marker and markedly stimulated monocyte mRNA expression of interleukin (IL)-6, IL-1β, IL-23, chemokine (C-C motif) ligand 4, and tumour necrosis factor α. STAT3 in monocytes was activated by increased endothelial stretch. Inhibition of STAT3, neutralization of IL-6 and scavenging of hydrogen peroxide prevented formation of intermediate monocytes in response to increased endothelial stretch. We also found evidence that nitric oxide (NO) inhibits formation of intermediate monocytes and STAT3 activation. In vivo studies demonstrated that humans with hypertension have increased intermediate and non-classical monocytes and that intermediate monocytes demonstrate evidence of STAT3 activation. Mice with experimental hypertension exhibit increased aortic and renal infiltration of monocytes, dendritic cells, and macrophages with activated STAT3.

Conclusions

These findings provide insight into how monocytes are activated by the vascular endothelium during hypertension. This is likely in part due to a loss of NO signalling and increased release of IL-6 and hydrogen peroxide by the dysfunctional endothelium and a parallel increase in STAT activation in adjacent monocytes. Interventions to enhance bioavailable NO, reduce IL-6 or hydrogen peroxide production or to inhibit STAT3 may have anti-inflammatory roles in hypertension and related conditions.

Inhibition of angiotensin II receptor I prevents inflammation and bone loss in periodontitis

BACKGROUND

Periodontal disease is characterized by alveolar bone destruction and degenerative lesions of the periodontal ligament (PDL); it is initiated by bacterial infection of the oral cavity, but the clinical effects are secondary to an aberrant host immune response. Primary hypertension (PH), which causes significant morbidity and mortality worldwide, has also been shown to be an inflammatory disease characterized by aberrant immune cell infiltration and activation. Clinical retrospective studies have shown a link between PH and periodontitis with PH exacerbating periodontitis and vice versa, but the pathophysiologic mechanisms responsible for this remain unknown.

METHODS

In this study, we investigate the underlying mechanisms behind PH exacerbation of periodontitis by using a bacteria-induced periodontitis model in normotensive and hypertensive (Nos3^-/- ) mice treated with or without an Angiotensin II (Ang II) specific receptor 1 (AT1) antagonist, losartan. The histologic analyses including immunohistochemistry, immunofluorescence were carried out. The qRT-PCR and ELISAs were applied for the target gene and protein detection.

RESULTS

We find that PH worsens bone resorption and PDL destruction in periodontitis and that treatment with losartan, rescues this. We also show that PH increases dendritic cell (DC) and osteoclast (OC) infiltration in periodontitis, which is also dependent on Ang II. Finally, we show that PH augments the pro-inflammatory state in periodontitis infiltrating DCs in an Ang II-dependent manner and use in vitro studies to show that Ang II directly augments DC Toll-like receptor 4 (TLR4) signaling.

CONCLUSION

Our studies show a central role for Ang II as a pro-inflammatory Toll-like receptor mediator in the pathogenesis of PH-exacerbated periodontitis, indicating that Ang II may be a reasonable target in patients with PH and periodontitis comorbidity.

Renal effects of cytokines in hypertension

PURPOSE OF REVIEW

Inflammatory cytokines contribute to the pathogenesis of hypertension through effects on renal blood flow and sodium handling. This review will update recent advances that explore the renal actions of immune cells and cytokines in the pathogenesis of hypertension.

RECENT FINDINGS

Populations of cells from both the innate and adaptive immune systems contribute to hypertension by modulating functions of the vasculature and epithelial cells in the kidney. Macrophages and T lymphocytes can directly regulate the hypertensive response and consequent target organ damage. Dendritic cells and B lymphocytes can alter blood pressure (BP) indirectly by facilitating T-cell activation. Proinflammatory cytokines, including tumor necrosis factor-α, interleukin 17, interleukin 1, and interferon-γ augment BP and/or renal injury when produced by T helper 1 cells, T helper 17 cells, and macrophages. In contrast, interleukin 10 improves vascular and renal functions in preclinical hypertension studies. The effects of transforming growth factor-β are complex because of its profibrotic and immunosuppressive functions that also depend on the localization and concentration of this pleiotropic cytokine.

SUMMARY

Preclinical studies point to a key role for cytokines in hypertension via their actions in the kidney. Consistent with this notion, anti-inflammatory therapies can attenuate BP elevation in human patients with rheumatologic disease. Conversely, impaired natriuresis may further polarize both T lymphocytes and macrophages toward a proinflammatory state, in a pathogenic, feed-forward loop of immune activation and BP elevation. Understanding the precise renal actions of cytokines in hypertension will be necessary to inhibit cytokine-dependent hypertensive responses while preserving systemic immunity and tumor surveillance.

Acute and 28-day repeated dose toxicity evaluations of 2-hydroxybenzylamine acetate in mice and rats

2-hydroxybenzylamine (2-HOBA), a compound naturally found in buckwheat, has been shown to protect cells and tissues from the damaging effects of oxidative stress. The purpose of this report was to evaluate 2-HOBA in preclinical oral rodent toxicity studies. This report includes the results from three oral toxicity studies in rodents: a preliminary 28-day feeding study in mice, a 14-day acute oral toxicity study in rats, and a 28-day repeated dose oral toxicity study in rats. The preliminary mouse feeding study showed no adverse effects of 2-HOBA at concentrations up to 0.456% by weight in feed, but decreased food intake and weight loss were observed at 1.56% 2-HOBA in the diet, likely due to poor palatability. In the acute dosing study, 2000 mg/kg BW 2-HOBA resulted in mortality in one of the six tested female rats, indicating a median lethal dose of 2500 mg/kg BW. In the 28-day repeated oral dose study, small differences were observed between 2-HOBA treated and control group rats, but none of these differences were determined to be of toxicological significance. Together, these studies support the lack of toxicity of oral administration of 2-HOBA acetate at doses up to 1000 mg/kg BW d^-1 in rodents.

Heat shock proteins and cardiovascular disease

The development of stress drives a host of biological responses that include the overproduction of a family of proteins named heat shock proteins (HSPs), because they were initially studied after heat exposure. HSPs are evolutionarily preserved proteins with a high degree of interspecies homology. HSPs are intracellular proteins that also have extracellular expression. The primary role of HSPs is to protect cell function by preventing irreversible protein damage and facilitating molecular traffic through intracellular pathways. However, in addition to their chaperone role, HSPs are immunodominant molecules that stimulate natural as well as disease-related immune reactivity. The latter may be a consequence of molecular mimicry, generating cross-reactivity between human HSPs and the HSPs of infectious agents. Autoimmune reactivity driven by HSPs could also be the result of enhancement of the immune response to peptides generated during cellular injury and of their role in the delivery of peptides to the major histocompatibility complex in antigen-presenting cells. In humans, HSPs have been found to participate in the pathogenesis of a large number of diseases. This review is focused on the role of HSPs in atherosclerosis and essential hypertension.

Role of immune cells in hypertension

Inflammatory processes have been shown to play an important role in the mechanisms involved in the pathogenesis of hypertension. Innate and adaptive immune responses participate in BP elevation and end-organ damage. Here, we discuss recent studies focusing on novel inflammatory and immune mechanisms that play roles in BP elevation. Different subpopulations of cells involved in innate and adaptive immune responses, such as dendritic cells, monocytes/macrophages and NK cells, on the one hand, and B and T lymphocytes, on the other, contribute to the vascular and kidney injury in hypertension. Unconventional innate-like T cells such as γδ T cells also participate in hypertensive mechanisms by priming both innate and adaptive immune cells, contributing to trigger vascular inflammation and BP elevation. These cells exert their effects in part via production of various cytokines including pro-inflammatory IFN-γ and IL-17 and anti-inflammatory IL-10. The present review summarizes some of these immune mechanisms that participate in the pathophysiology of hypertension. LINKED ARTICLES: This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

The emerging alliance of sphingosine-1-phosphate signalling and immune cells: from basic mechanisms to implications in hypertension

The immune system plays a considerable role in hypertension. In particular, T-lymphocytes are recognized as important players in its pathogenesis. Despite substantial experimental efforts, the molecular mechanisms underlying the nature of T-cell activation contributing to an onset of hypertension or disease perpetuation are still elusive. Amongst other cell types, lymphocytes express distinct profiles of GPCRs for sphingosine-1-phosphate (S1P) - a bioactive phospholipid that is involved in many critical cell processes and most importantly majorly regulates T-cell development, lymphocyte recirculation, tissue-homing patterns and chemotactic responses. Recent findings have revealed a key role for S1P chemotaxis and T-cell mobilization for the onset of experimental hypertension, and elevated circulating S1P levels have been linked to several inflammation-associated diseases including hypertension in patients. In this article, we review the recent progress towards understanding how S1P and its receptors regulate immune cell trafficking and function and its potential relevance for the pathophysiology of hypertension. LINKED ARTICLES: This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

Nox2 in regulatory T cells promotes angiotensin II-induced cardiovascular remodeling

The superoxide-generating enzyme Nox2 contributes to hypertension and cardiovascular remodeling triggered by activation of the renin-angiotensin system. Multiple Nox2-expressing cells are implicated in angiotensin II-induced (Ang II-induced) pathophysiology, but the importance of Nox2 in leukocyte subsets is poorly understood. Here, we investigated the role of Nox2 in T cells, particularly Tregs. Mice globally deficient in Nox2 displayed increased numbers of Tregs in the heart at baseline, whereas Ang II-induced effector T cell (Teff) infiltration was inhibited. To investigate the role of Treg Nox2, we generated a mouse line with CD4-targeted Nox2 deficiency (Nox2fl/flCD4Cre+). These animals showed inhibition of Ang II-induced hypertension and cardiac remodeling related to increased tissue-resident Tregs and reduction in infiltrating Teffs, including Th17 cells. The protection in Nox2fl/flCD4Cre+ mice was reversed by anti-CD25 antibody depletion of Tregs. Mechanistically, Nox2-/y Tregs showed higher in vitro suppression of Teff proliferation than WT Tregs, increased nuclear levels of FoxP3 and NF-κB, and enhanced transcription of CD25, CD39, and CD73. Adoptive transfer of Tregs confirmed that Nox2-deficient cells had greater inhibitory effects on Ang II-induced heart remodeling than WT cells. These results identify a previously unrecognized role of Nox2 in modulating suppression of Tregs, which acts to enhance hypertension and cardiac remodeling.

Inflammatory Signaling in Hypertension: Regulation of Adrenal Catecholamine Biosynthesis

The immune system is increasingly recognized for its role in the genesis and progression of hypertension. The adrenal gland is a major site that coordinates the stress response via the hypothalamic-pituitary-adrenal axis and the sympathetic-adrenal system. Catecholamines released from the adrenal medulla function in the neuro-hormonal regulation of blood pressure and have a well-established link to hypertension. The immune system has an active role in the progression of hypertension and cytokines are powerful modulators of adrenal cell function. Adrenal medullary cells integrate neural, hormonal, and immune signals. Changes in adrenal cytokines during the progression of hypertension may promote blood pressure elevation by influencing catecholamine biosynthesis. This review highlights the potential interactions of cytokine signaling networks with those of catecholamine biosynthesis within the adrenal, and discusses the role of cytokines in the coordination of blood pressure regulation and the stress response.

Immune cell trafficking, lymphatics and hypertension

Activated immune cell infiltration into organs contributes to the development and maintenance of hypertension. Studies targeting specific immune cell populations or reducing their inflammatory signalling have demonstrated a reduction in BP. Lymphatic vessels play a key role in immune cell trafficking and in resolving inflammation, but little is known about their role in hypertension. Studies from our laboratory and others suggest that inflammation-associated or induction of lymphangiogenesis is organ protective and anti-hypertensive. This review provides the basis for hypertension as a disease of chronic inflammation in various tissues and highlights how renal lymphangiogenesis is a novel regulator of kidney health and BP. LINKED ARTICLES: This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

Human monocyte transcriptional profiling identifies IL-18 receptor accessory protein and lactoferrin as novel immune targets in hypertension

BACKGROUND AND PURPOSE

Monocytes play a critical role in hypertension. The purpose of our study was to use an unbiased approach to determine whether hypertensive individuals on conventional therapy exhibit an altered monocyte gene expression profile and to perform validation studies of selected genes to identify novel therapeutic targets for hypertension.

EXPERIMENTAL APPROACH

Next generation RNA sequencing identified differentially expressed genes in a small discovery cohort of normotensive and hypertensive individuals. Several of these genes were further investigated for association with hypertension in multiple validation cohorts using qRT-PCR, regression analysis, phenome-wide association study and case-control analysis of a missense polymorphism.

KEY RESULTS

We identified 60 genes that were significantly differentially expressed in hypertensive monocytes, many of which are related to IL-1β. Uni- and multivariate regression analyses of the expression of these genes with mean arterial pressure (MAP) revealed four genes that significantly correlated with MAP in normotensive and/or hypertensive individuals. Of these, lactoferrin (LTF), peptidoglycan recognition protein 1 and IL-18 receptor accessory protein (IL18RAP) remained significantly elevated in peripheral monocytes of hypertensive individuals in a separate validation cohort. Interestingly, IL18RAP expression associated with MAP in a cohort of African Americans. Furthermore, homozygosity for a missense single nucleotide polymorphism in LTF that decreases antimicrobial function and increases protein levels (rs1126478) was over-represented in patients with hypertension relative to controls (odds ratio 1.16).

CONCLUSIONS AND IMPLICATIONS

These data demonstrate that monocytes exhibit enhanced pro-inflammatory gene expression in hypertensive individuals and identify IL18RAP and LTF as potential novel mediators of human hypertension.

LINKED ARTICLES

This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

Salt, inflammation, IL-17 and hypertension

Traditionally, arterial hypertension and subsequent end-organ damage have been attributed to haemodynamic factors, but increasing evidence indicates that inflammation also contributes to the deleterious consequences of this disease. The immune system has evolved to prevent invasion of foreign microorganisms and to promote tissue healing after injury. However, this beneficial activity comes at a cost of collateral damage when the immune system overreacts to internal injury, such as prehypertension. Over the past few years, important findings have revolutionized hypertension research. Firstly, in 2007, a seminal paper showed that adaptive immunity is involved in the pathogenesis of hypertension. Secondly, salt storage in the skin and its consequences for cardiovascular physiology were discovered. Thirdly, after the discovery that salt promotes the differentiation of CD4⁺ T cells into T_H 17 cells, it was demonstrated that salt directly changes several cells of the innate and adaptive immune system and aggravates autoimmune disease but may improve antimicrobial defence. Herein, we will review pathways of activation of immune cells by salt in hypertension as the framework for understanding the multiple roles of salt and immunity in arterial hypertension and autoimmune disease. LINKED ARTICLES: This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

Dendritic Cell Amiloride-Sensitive Channels Mediate Sodium-Induced Inflammation and Hypertension

Sodium accumulates in the interstitium and promotes inflammation through poorly defined mechanisms. We describe a pathway by which sodium enters dendritic cells (DCs) through amiloride-sensitive channels including the alpha and gamma subunits of the epithelial sodium channel and the sodium hydrogen exchanger 1. This leads to calcium influx via the sodium calcium exchanger, activation of protein kinase C (PKC), phosphorylation of p47^phox, and association of p47^phox with gp91^phox. The assembled NADPH oxidase produces superoxide with subsequent formation of immunogenic isolevuglandin (IsoLG)-protein adducts. DCs activated by excess sodium produce increased interleukin-1β (IL-1β) and promote T cell production of cytokines IL-17A and interferon gamma (IFN-γ). When adoptively transferred into naive mice, these DCs prime hypertension in response to a sub-pressor dose of angiotensin II. These findings provide a mechanistic link between salt, inflammation, and hypertension involving increased oxidative stress and IsoLG production in DCs.

The role of infiltrating immune cells in dysfunctional adipose tissue

Adipose tissue (AT) dysfunction, characterized by loss of its homeostatic functions, is a hallmark of non-communicable diseases. It is characterized by chronic low-grade inflammation and is observed in obesity, metabolic disorders such as insulin resistance and diabetes. While classically it has been identified by increased cytokine or chemokine expression, such as increased MCP-1, RANTES, IL-6, interferon (IFN) gamma or TNFα, mechanistically, immune cell infiltration is a prominent feature of the dysfunctional AT. These immune cells include M1 and M2 macrophages, effector and memory T cells, IL-10 producing FoxP3+ T regulatory cells, natural killer and NKT cells and granulocytes. Immune composition varies, depending on the stage and the type of pathology. Infiltrating immune cells not only produce cytokines but also metalloproteinases, reactive oxygen species, and chemokines that participate in tissue remodelling, cell signalling, and regulation of immunity. The presence of inflammatory cells in AT affects adjacent tissues and organs. In blood vessels, perivascular AT inflammation leads to vascular remodelling, superoxide production, endothelial dysfunction with loss of nitric oxide (NO) bioavailability, contributing to vascular disease, atherosclerosis, and plaque instability. Dysfunctional AT also releases adipokines such as leptin, resistin, and visfatin that promote metabolic dysfunction, alter systemic homeostasis, sympathetic outflow, glucose handling, and insulin sensitivity. Anti-inflammatory and protective adiponectin is reduced. AT may also serve as an important reservoir and possible site of activation in autoimmune-mediated and inflammatory diseases. Thus, reciprocal regulation between immune cell infiltration and AT dysfunction is a promising future therapeutic target.

The role of autoimmune reactivity induced by heat shock protein 70 in the pathogenesis of essential hypertension

Autoimmunity is increasingly recognized as having a central role in essential hypertension. Heat shock proteins (HSPs) are immunodominant molecules with high interspecies homology and autoimmune reactivity directed against HSP70 may play a role in the pathogenesis of hypertension. Autoimmunity to HSP70 may result from molecular mimicry between human HSP and bacterial HSP or, alternatively, as a response to HSP70-peptide complexes generated during cellular stress and delivered to the major histocompatibility complex by antigen-presenting cells. HSP70 is increased in the circulation and kidney of hypertensive patients, and genetic polymorphisms of HSP70 are associated with essential hypertension. Depending on the route and conditions of administration, HSP70 may induce or suppress immune-related inflammation. Renal inflammation induced by immunity to HSP70 causes hypertension in laboratory animals, and administration of specific peptide sequences of HSP70 results in a protective anti-inflammatory response that prevents and corrects salt-induced hypertension. Potential therapeutic uses of HSP70 in essential hypertension deserve to be investigated. LINKED ARTICLES: This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

Modification by isolevuglandins, highly reactive γ-ketoaldehydes, deleteriously alters high-density lipoprotein structure and function

Cardiovascular disease risk depends on high-density lipoprotein (HDL) function, not HDL-cholesterol. Isolevuglandins (IsoLGs) are lipid dicarbonyls that react with lysine residues of proteins and phosphatidylethanolamine. IsoLG adducts are elevated in atherosclerosis. The consequences of IsoLG modification of HDL have not been studied. We hypothesized that IsoLG modification of apoA-I deleteriously alters HDL function. We determined the effect of IsoLG on HDL structure-function and whether pentylpyridoxamine (PPM), a dicarbonyl scavenger, can preserve HDL function. IsoLG adducts in HDL derived from patients with familial hypercholesterolemia (n = 10, 233.4 ± 158.3 ng/mg) were found to be significantly higher than in healthy controls (n = 7, 90.1 ± 33.4 pg/mg protein). Further, HDL exposed to myeloperoxidase had elevated IsoLG-lysine adducts (5.7 ng/mg protein) compared with unexposed HDL (0.5 ng/mg protein). Preincubation with PPM reduced IsoLG-lysine adducts by 67%, whereas its inactive analogue pentylpyridoxine did not. The addition of IsoLG produced apoA-I and apoA-II cross-links beginning at 0.3 molar eq of IsoLG/mol of apoA-I (0.3 eq), whereas succinylaldehyde and 4-hydroxynonenal required 10 and 30 eq. IsoLG increased HDL size, generating a subpopulation of 16-23 nm. 1 eq of IsoLG decreased HDL-mediated [³H]cholesterol efflux from macrophages via ABCA1, which corresponded to a decrease in HDL-apoA-I exchange from 47.4% to only 24.8%. This suggests that IsoLG inhibits apoA-I from disassociating from HDL to interact with ABCA1. The addition of 0.3 eq of IsoLG ablated HDL's ability to inhibit LPS-stimulated cytokine expression by macrophages and increased IL-1β expression by 3.5-fold. The structural-functional effects were partially rescued with PPM scavenging.

Role of afferent and efferent renal nerves in the development of AngII-salt hypertension in rats

Hypertension is the leading modifiable risk factor for death worldwide, yet the causes remain unclear and treatment remains suboptimal. Catheter-based renal denervation (RDNX) is a promising new treatment for resistant hypertension, but the mechanisms underlying its antihypertensive effect remain unclear. We recently found that RDNX attenuates deoxycorticosterone acetate-salt hypertension and that this is dependent on ablation of afferent renal nerves and is associated with decreased renal inflammation. To determine if this is common to other models of salt-sensitive hypertension, rats underwent complete RDNX (n = 8), selective ablation of afferent renal nerves (n = 8), or sham denervation (n = 8). Mean arterial pressure (MAP) and heart rate were measure by telemetry and rats were housed in metabolic cages for measurement of sodium and water balance. Rats were then subjected to angiotensin II (AngII)-salt hypertension (10 ng/kg/min, intravenous + 4% NaCl diet) for 2 weeks. At the end of the study, renal T-cell infiltration was quantified by flow cytometry. AngII resulted in an increase in MAP of ~50 mmHg in all three groups with no between group differences, and a transient bradycardia that was blunted by selective ablation of afferent renal nerves. Sodium and water balance were unaffected by AngII-salt treatment and similar between groups. Lastly, AngII infusion was not associated with T-cell infiltration into the kidneys, and T-cell counts were unaffected by the denervation procedures. These results suggest that AngII-salt hypertension in the rat is not associated with renal inflammation and that neither afferent nor efferent renal nerves contribute to this model.

Myeloid CD11c+ Antigen-Presenting Cells Ablation Prevents Hypertension in Response to Angiotensin II Plus High-Salt Diet

Increasing evidence shows that antigen-presenting cells (APCs) are involved in the development of inflammation associated to hypertension. However, the potential role of APCs in the modulation of renal sodium transport has not been addressed. We hypothesized that APCs participate in renal sodium transport and, thus, development of high blood pressure in response to angiotensin II plus a high-salt diet. Using transgenic mice that allow the ablation of CD11c^high APCs, we studied renal sodium transport, the intrarenal renin-angiotensin system components, blood pressure, and cardiac/renal tissue damage in response to angiotensin II plus a high-salt diet. Strikingly, we found that APCs are required for the development of hypertension and that the ablation/restitution of APCs produces rapid changes in the blood pressure in mice with angiotensin II plus a high-salt diet. Moreover, APCs were necessary for the induction of intrarenal renin-angiotensin system components and affected the modulation of natriuresis and tubular sodium transporters. Consistent with the prevention of hypertension, the ablation of APCs also prevented cardiac hypertrophy and the induction of several indicators of renal and cardiac damage. Thus, our findings indicate a prominent role of APCs as modulators of blood pressure by mechanisms including renal sodium handling, with kinetics that suggest the involvement of tubular cell functions in addition to the modulation of inflammation and adaptive immune response.

The Role of Dendritic and Endothelial Cells in Cardiorenal Syndrome

BACKGROUNDS

Dendritic cells (DCs) are antigen-presenting cells that play a central role in innate and adaptive immune responses; however, the cross talk between cardiac and renal DCs in cardiorenal syndrome (CRS) has not yet been fully elucidated. In this setting, endothelial cells (ECs) also contribute to immune responses.

SUMMARY

DC and EC activation and dysfunction have a central role in the pathogenesis of CRS. Regarding immune responses in CRS, it is unknown whether ECs may serve as antigen-presenting cells or act synergistically with DCs to actively participate in innate and adaptive immune responses. This review first focuses on the burden of concomitant heart and renal DCs in the context of CRS; it examines what is known of DCs in animal models, and proposes a central role for DCs in all types of CRS. Second, this review briefly describes the role of ECs in the context of CRS. Key Messages: Understanding the role of DCs and ECs in immune response could lead to the development of novel therapies for the prevention and treatment of CRS.

Dichotomous roles of co-stimulatory molecules in diabetes mellitus

Numerous studies have established the importance of immune dysfunction in the development of diabetes mellitus, including typ1 and typ2 diabetes, and it is worth noting that T cell activation acts a key role in the pathogenesis of loss of β cell mass, adipose inflammation and insulin resistance. Regarding as an important checkpoint in the process of T cell activation, co-stimulatory molecules interaction between antigen present cells and T cells have been identified the critical role in the development of diabetes mellitus. Thus, blockage of co-stimulatory dyads interaction between antigen present cells and T cells was supposed to a potential of therapeutic strategies. However, studies also showed that inhibition or deletion of some co-stimulatory molecules do not always reduce the development of diabetes, and even exacerbate the disease activity. Here, in this context, we highlight the dichotomous role of co-stimulatory molecules interaction in the pathogenesis of diabetes.

The immunology of hypertension

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 cells in which they are formed and T cell activation. Efforts to prevent and reverse immune activation may prove beneficial in preventing the long-term sequelae of hypertension and its related cardiovascular diseases.

Macrophages under pressure: the role of macrophage polarization in hypertension

Hypertension is a multifactorial disease involving the nervous, renal, and cardiovascular systems. Macrophages are the most abundant and ubiquitous immune cells, placing them in a unique position to serve as key mediators between these components. The polarization of macrophages confers vast phenotypic and functional plasticity, allowing them to act as proinflammatory, homeostatic, and anti-inflammatory agents. Key differences between the M1 and M2 phenotypes, the 2 subsets at the extremes of this polarization spectrum, place macrophages at a juncture to mediate many mechanisms involved in the pathogenesis of hypertension. Neuronal and non-neuronal regulation of the immune system, that is, the "neuroimmuno" axis, plays an integral role in the polarization of macrophages. In hypertension, the neuroimmuno axis results in synchronization of macrophage mobilization from immune cell reservoirs and their chemotaxis, via increased expression of chemoattractants, to end organs critical in the development of hypertension. This complicated system is largely coordinated by the dichotomous actions of the autonomic neuronal and non-neuronal activation of cholinergic, adrenergic, and neurohormonal receptors on macrophages, leading to their ability to "switch" between phenotypes at sites of active inflammation. Data from experimental models and human studies are in concordance with each other and support a central role for macrophage polarization in the pathogenesis of hypertension.

Association of Antibodies to Citrullinated Protein Antigens with Blood Pressure in First-Degree Relatives of Rheumatoid Arthritis Patients: The Studies of the Etiology of Rheumatoid Arthritis

BACKGROUND

Hypertension is more common in patients with rheumatoid arthritis (RA) than in the general population. It is unknown whether hypertension is due to RA-related medications or the disease itself. Therefore, we sought to investigate associations between RA-related autoantibodies, specifically antibodies to citrullinated protein antigens (ACPA) and systolic blood pressure (SBP) and diastolic blood pressure (DBP) in first-degree relatives of RA patients, who were free of RA and RA-related medications. We hypothesized that a greater number of detectable ACPA would be associated with high SBP and DBP, independent of other risk factors in these first-degree relatives.

METHODS

We evaluated associations between ACPA and SBP and DBP in a cross-sectional study of 72 first-degree relatives (defined as parent, child, or sibling) of RA patients. Fifteen ACPA were measured using a Bio-Plex bead-based assay; each was dichotomized as positive/negative based on pre-specified cut-points. Analysis of covariance was used to evaluate associations between ACPA positivity and SBP and DBP, adjusting for age, sex, race, body mass index (BMI), pack-years of smoking, high sensitivity C-reactive protein (hsCRP), and current use of anti-hypertensive medications.

RESULTS

Average age was 51 and 69% were women. Mean SBP was 119 ± 18 and DBP was 74 ± 9 mm Hg. Thirty-three (46%) first-degree relatives were positive for ≥1 ACPA; and were younger, had lower BMI, more pack-years of smoking, and higher hsCRP concentrations compared to ACPA negative first-degree relatives. For each additional positive ACPA, SBP was 0.98 ± 0.5 mm Hg (p = 0.05) higher, and DBP was 0.66 ± 0.3 mm Hg (p = 0.04) higher. Anti-cit-fibrinogen A (211-230) positive and anti-cit-filaggrin positive first-degree relatives had 11.5 and 13.9 mm Hg higher SBP (p = 0.02) respectively. Anti-cit-clusterin, cit-filaggrin, and cit-vimentin positive first-degree relatives had 7-8 mm Hg higher DBP (p = 0.03, 0.05, 0.05 respectively), compared to being negative for these individual ACPA. Consistent with associations between ACPA, SBP, and DBP, anti-cyclic citrullinated peptides (anti-CCP2) positive first-degree relatives had 16.4± (p = 0.03) higher SBP and 12.1± mm Hg (p = 0.01) higher DBP than anti-CCP2 negative first-degree relatives.

CONCLUSION

In first-degree relatives without RA, ACPA positivity is associated with higher SBP and DBP. Subclinical autoimmune processes and ACPA may play a role in the vascular changes potentially leading to hypertension prior to RA onset.

Scavengers of reactive γ-ketoaldehydes extend Caenorhabditis elegans lifespan and healthspan through protein-level interactions with SIR-2.1 and ETS-7

Isoketals (IsoKs) are highly reactive γ-ketoaldehyde products of lipid peroxidation that covalently adduct lysine side chains in proteins, impairing their function. Using C. elegans as a model organism, we sought to test the hypothesis that IsoKs contribute to molecular aging through adduction and inactivation of specific protein targets, and that this process can be abrogated using salicylamine (SA), a selective IsoK scavenger. Treatment with SA extends adult nematode longevity by nearly 56% and prevents multiple deleterious age-related biochemical and functional changes. Testing of a variety of molecular targets for SA's action revealed the sirtuin SIR-2.1 as the leading candidate. When SA was administered to a SIR-2.1 knockout strain, the effects on lifespan and healthspan extension were abolished. The SIR-2.1-dependent effects of SA were not mediated by large changes in gene expression programs or by significant changes in mitochondrial function. However, expression array analysis did show SA-dependent regulation of the transcription factor ets-7 and associated genes. In ets-7 knockout worms, SA's longevity effects were abolished, similar to sir-2.1 knockouts. However, SA dose-dependently increases ets-7 mRNA levels in non-functional SIR-2.1 mutant, suggesting that both are necessary for SA's complete lifespan and healthspan extension.

Salt, Hypertension, and Immunity

The link between inappropriate salt retention in the kidney and hypertension is well recognized. However, growing evidence suggests that the immune system can play surprising roles in sodium homeostasis, such that the study of inflammatory cells and their secreted effectors has provided important insights into salt sensitivity. As part of the innate immune system, myeloid cells have diverse roles in blood pressure regulation, ranging from prohypertensive actions in the kidney, vasculature, and brain, to effects in the skin that attenuate blood pressure elevation. In parallel, T lymphocyte subsets, as key constituents of the adaptive immune compartment, have variable effects on renal sodium handling and the hypertensive response, accruing from the functions of the cytokines that they produce. Conversely, salt can directly modulate the phenotypes of myeloid and T cells, illustrating bidirectional regulatory mechanisms through which sodium and the immune system coordinately impact blood pressure. This review details the complex interplay between myeloid cells, T cells, and salt in the pathogenesis of essential hypertension.

Progressive Renal Disease Established by Renin-Coding Adeno-Associated Virus-Driven Hypertension in Diverse Diabetic Models

Progress in research and developing therapeutics to prevent diabetic kidney disease (DKD) is limited by a lack of animal models exhibiting progressive kidney disease. Chronic hypertension, a driving factor of disease progression in human patients, is lacking in most available models of diabetes. We hypothesized that superimposition of hypertension on diabetic mouse models would accelerate DKD. To test this possibility, we induced persistent hypertension in three mouse models of type 1 diabetes and two models of type 2 diabetes by adeno-associated virus delivery of renin (ReninAAV). Compared with LacZAAV-treated counterparts, ReninAAV-treated type 1 diabetic Akita/129 mice exhibited a substantial increase in albumin-to-creatinine ratio (ACR) and serum creatinine level and more severe renal lesions. In type 2 models of diabetes (C57BKLS db/db and BTBR ob/ob mice), compared with LacZAAV, ReninAAV induced significant elevations in ACR and increased the incidence and severity of histopathologic findings, with increased serum creatinine detected only in the ReninAAV-treated db/db mice. The uninephrectomized ReninAAV db/db model was the most progressive model examined and further characterized. In this model, separate treatment of hyperglycemia with rosiglitazone or hypertension with lisinopril partially reduced ACR, consistent with independent contributions of these disorders to renal disease. Microarray analysis and comparison with human DKD showed common pathways affected in human disease and this model. These results identify novel models of progressive DKD that provide researchers with a facile and reliable method to study disease pathogenesis and support the development of therapeutics.

Th1 effector T cells selectively orchestrate cardiac fibrosis in nonischemic heart failure

Despite emerging data indicating a role for T cells in profibrotic cardiac repair and healing after ischemia, little is known about whether T cells directly impact cardiac fibroblasts (CFBs) to promote cardiac fibrosis (CF) in nonischemic heart failure (HF). Recently, we reported increased T cell infiltration in the fibrotic myocardium of nonischemic HF patients, as well as the protection from CF and HF in TCR-α^-/- mice. Here, we report that T cells activated in such a context are mainly IFN-γ⁺, adhere to CFB, and induce their transition into myofibroblasts. Th1 effector cells selectively drive CF both in vitro and in vivo, whereas adoptive transfer of Th1 cells, opposite to activated IFN-γ^-/- Th cells, partially reconstituted CF and HF in TCR-α^-/- recipient mice. Mechanistically, Th1 cells use integrin α4 to adhere to and induce TGF-β in CFB in an IFN-γ-dependent manner. Our findings identify a previously unrecognized role for Th1 cells as integrators of perivascular CF and cardiac dysfunction in nonischemic HF.

Chemistry and analysis of HNE and other prominent carbonyl-containing lipid oxidation compounds

The process of lipid oxidation generates a diverse array of small aldehydes and carbonyl-containing compounds, which may occur in free form or esterified within phospholipids and cholesterol esters. These aldehydes mostly result from fragmentation of fatty acyl chains following radical oxidation, and the products can be subdivided into alkanals, alkenals (usually α,β-unsaturated), γ-substituted alkenals and bis-aldehydes. Isolevuglandins are non-fragmented di-carbonyl compounds derived from H₂-isoprostanes, and oxidation of the ω-3-fatty acid docosahexenoic acid yield analogous 22 carbon neuroketals. Non-radical oxidation by hypochlorous acid can generate α-chlorofatty aldehydes from plasmenyl phospholipids. Most of these compounds are reactive and have generally been considered as toxic products of a deleterious process. The reactivity is especially high for the α,β-unsaturated alkenals, such as acrolein and crotonaldehyde, and for γ-substituted alkenals, of which 4-hydroxy-2-nonenal and 4-oxo-2-nonenal are best known. Nevertheless, in recent years several previously neglected aldehydes have been investigated and also found to have significant reactivity and biological effects; notable examples are 4-hydroxy-2-hexenal and 4-hydroxy-dodecadienal. This has led to substantial interest in the biological effects of all of these lipid oxidation products and their roles in disease, including proposals that HNE is a second messenger or signalling molecule. However, it is becoming clear that many of the effects elicited by these compounds relate to their propensity for forming adducts with nucleophilic groups on proteins, DNA and specific phospholipids. This emphasizes the need for good analytical methods, not just for free lipid oxidation products but also for the resulting adducts with biomolecules. The most informative methods are those utilizing HPLC separations and mass spectrometry, although analysis of the wide variety of possible adducts is very challenging. Nevertheless, evidence for the occurrence of lipid-derived aldehyde adducts in biological and clinical samples is building, and offers an exciting area of future research.

Perivascular adipose tissue inflammation in vascular disease

Perivascular adipose tissue (PVAT) plays a critical role in the pathogenesis of cardiovascular disease. In vascular pathologies, perivascular adipose tissue increases in volume and becomes dysfunctional, with altered cellular composition and molecular characteristics. PVAT dysfunction is characterized by its inflammatory character, oxidative stress, diminished production of vaso-protective adipocyte-derived relaxing factors and increased production of paracrine factors such as resistin, leptin, cytokines (IL-6 and TNF-α) and chemokines [RANTES (CCL5) and MCP-1 (CCL2)]. These adipocyte-derived factors initiate and orchestrate inflammatory cell infiltration including primarily T cells, macrophages, dendritic cells, B cells and NK cells. Protective factors such as adiponectin can reduce NADPH oxidase superoxide production and increase NO bioavailability in the vessel wall, while inflammation (e.g. IFN-γ or IL-17) induces vascular oxidases and eNOS dysfunction in the endothelium, vascular smooth muscle cells and adventitial fibroblasts. All of these events link the dysfunctional perivascular fat to vascular dysfunction. These mechanisms are important in the context of a number of cardiovascular disorders including atherosclerosis, hypertension, diabetes and obesity. Inflammatory changes in PVAT's molecular and cellular responses are uniquely different from classical visceral or subcutaneous adipose tissue or from adventitia, emphasizing the unique structural and functional features of this adipose tissue compartment. Therefore, it is essential to develop techniques for monitoring the characteristics of PVAT and assessing its inflammation. This will lead to a better understanding of the early stages of vascular pathologies and the development of new therapeutic strategies focusing on perivascular adipose tissue.

LINKED ARTICLES

This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.

The effect of oxidized phospholipids on phenotypic polarization and function of macrophages

Oxidized phospholipids are products of lipid oxidation that are found on oxidized low-density lipoproteins and apoptotic cell membranes. These biologically active lipids were shown to affect a variety of cell types and attributed pro-as well as anti-inflammatory effects. In particular, macrophages exposed to oxidized phospholipids drastically change their gene expression pattern and function. These 'Mox,'macrophages were identified in atherosclerotic lesions, however, it remains unclear how lipid oxidation products are sensed by macrophages and how they influence their biological function. Here, we review recent developments in the field that provide insight into the structure, recognition, and downstream signaling of oxidized phospholipids in macrophages.

A new paradigm of sodium regulation in inflammation and hypertension

Dysregulation of sodium (Na⁺) balance is a major cause of hypertensive cardiovascular disease. The current dogma is that interstitial Na⁺ readily equilibrates with plasma and that renal excretion and reabsorption is sufficient to regulate extracellular fluid volume and control blood pressure. These ideas have been recently challenged by the discovery that Na⁺ accumulates in tissues without commensurate volume retention and activates immune cells, leading to hypertension and autoimmune disease. However, objections have been raised to this new paradigm, with some investigators concerned about where and how salt is stored in tissues. Further concerns also include how Na⁺ is mobilized from tissue stores and how it interacts with various organ systems to cause hypertension and end-organ damage. This review assesses these two paradigms of Na⁺ regulation in the context of inflammation-mediated hypertension and cardiovascular disease pathogenesis. Also highlighted are future perspectives and important gaps in our understanding of how Na⁺ is linked to inflammation and hypertension. Understanding mechanisms of salt and body fluid regulation is the sine qua non of research efforts to identify therapeutic targets for hypertension and cardiovascular disease.

Association between chronic idiopathic urticaria and hypertension: A population-based retrospective cohort study

BACKGROUND

Chronic idiopathic urticaria (CIU) is defined as urticaria that is not caused by external triggers. The pathogenesis of CIU remains unknown. A previous study investigated whether hypertension is associated with extended duration of CIU.

OBJECTIVE

To investigate the possible association between CIU and hypertension.

METHODS

We performed a population-based retrospective cohort study of 2,460 patients with CIU and 9,840 age-, sex-, and index year-matched comparison patients, using the National Health Insurance of Taiwan database. The median follow-up periods were 7.13 years for the CIU cohort and 7.20 years for the non-CIU cohort. The distributions by sex and age were similar for both cohorts.

RESULTS

The CIU cohort had a 1.37-fold (95% CI, 1.22-1.53) greater risk of developing subsequent hypertension than the non-CIU cohort after adjusting for sex, age, comorbidities, and nonsedating antihistamine use.

CONCLUSION

This nationwide retrospective cohort study found that CIU is associated with a higher future risk of hypertension after adjusting for sex, age, comorbidities, and nonsedating antihistamine use. The detailed pathophysiologic mechanisms require further clarification in prospective studies.

Redox regulation of cardiovascular inflammation - Immunomodulatory function of mitochondrial and Nox-derived reactive oxygen and nitrogen species

Oxidative stress is a major hallmark of cardiovascular diseases although a causal link was so far not proven by large clinical trials. However, there is a close association between oxidative stress and inflammation and increasing evidence for a causal role of (low-grade) inflammation for the onset and progression of cardiovascular diseases, which may serve as the missing link between oxidative stress and cardiovascular morbidity and mortality. With the present review we would like to highlight the multiple redox regulated pathways in inflammation, discuss the sources of reactive oxygen and nitrogen species that are of interest for these processes and finally discuss the importance of angiotensin II (AT-II) as a trigger of cardiovascular inflammation and the initiation and progression of cardiovascular diseases.

A salt-sensing kinase in T lymphocytes, SGK1, drives hypertension and hypertensive end-organ damage

We previously showed that angiotensin II (Ang II) increases T cell production of IL-17A, and that mice deficient in IL-17A have blunted hypertension and attenuated renal and vascular dysfunction. It was recently shown that salt enhances IL-17A production from CD4+ T cells via a serum- and glucocorticoid-regulated kinase 1-dependent (SGK1-dependent) pathway. Thus, we tested the hypothesis that SGK1 signaling in T cells promotes hypertension and contributes to end-organ damage. We show that loss of T cell SGK1 results in a blunted hypertensive response to Ang II infusion by 25 mmHg. Importantly, renal and vascular inflammation is abrogated in these mice compared with control mice. Furthermore, mice lacking T cell SGK1 are protected from Ang II-induced endothelial dysfunction and renal injury. Loss of T cell SGK1 also blunts blood pressure and vascular inflammation in response to deoxycorticosterone acetate-salt (DOCA-salt) hypertension. Finally, we demonstrate that the Na+-K+-2Cl- cotransporter 1 (NKCC1) is upregulated in Th17 cells and is necessary for the salt-induced increase in SGK1 and the IL-23 receptor. These studies demonstrate that T cell SGK1 and NKCC1 may be novel therapeutic targets for the treatment of hypertension and identify a potentially new mechanism by which salt contributes to hypertension.

Recent Advances in Immunity and Hypertension

Persistent immune system activation plays an important role in the development of various forms of hypertension. Activation of the innate immune system, inflammation, and subsequent adaptive immune system response causing end-organ injury and dysfunction ultimately leads to hypertension and its associated sequelae including coronary artery disease, heart failure, stroke, and chronic kidney disease. In this review, we will provide updates on the innate and adaptive immune cells involved in hypertension, the current understanding of how the immune system gets activated, and examine the recently discovered mechanisms involved in several forms of experimental hypertension.

Role of the Immune System in Hypertension

High blood pressure is present in more than one billion adults worldwide and is the most important modifiable risk factor of death resulting from cardiovascular disease. While many factors contribute to the pathogenesis of hypertension, a role of the immune system has been firmly established by a large number of investigations from many laboratories around the world. Immunosuppressive drugs and inhibition of individual cytokines prevent or ameliorate experimental hypertension, and studies in genetically-modified mouse strains have demonstrated that lymphocytes are necessary participants in the development of hypertension and in hypertensive organ injury. Furthermore, immune reactivity may be the driving force of hypertension in autoimmune diseases. Infiltration of immune cells, oxidative stress, and stimulation of the intrarenal angiotensin system are induced by activation of the innate and adaptive immunity. High blood pressure results from the combined effects of inflammation-induced impairment in the pressure natriuresis relationship, dysfunctional vascular relaxation, and overactivity of the sympathetic nervous system. Imbalances between proinflammatory effector responses and anti-inflammatory responses of regulatory T cells to a large extent determine the severity of inflammation. Experimental and human studies have uncovered autoantigens (isoketal-modified proteins and heat shock protein 70) of potential clinical relevance. Further investigations on the immune reactivity in hypertension may result in the identification of new strategies for the treatment of the disease.

Radiation-Induced Fibrosis: Mechanisms and Opportunities to Mitigate. Report of an NCI Workshop, September 19, 2016

A workshop entitled "Radiation-Induced Fibrosis: Mechanisms and Opportunities to Mitigate" (held in Rockville, MD, September 19, 2016) was organized by the Radiation Research Program and Radiation Oncology Branch of the Center for Cancer Research (CCR) of the National Cancer Institute (NCI), to identify critical research areas and directions that will advance the understanding of radiation-induced fibrosis (RIF) and accelerate the development of strategies to mitigate or treat it. Experts in radiation biology, radiation oncology and related fields met to identify and prioritize the key areas for future research and clinical translation. The consensus was that several known and newly identified targets can prevent or mitigate RIF in pre-clinical models. Further, basic and translational research and focused clinical trials are needed to identify optimal agents and strategies for therapeutic use. It was felt that optimally designed preclinical models are needed to better study biomarkers that predict for development of RIF, as well as to understand when effective therapies need to be initiated in relationship to manifestation of injury. Integrating appropriate endpoints and defining efficacy in clinical trials testing treatment of RIF were felt to be critical to demonstrating efficacy. The objective of this meeting report is to (a) highlight the significance of RIF in a global context, (b) summarize recent advances in our understanding of mechanisms of RIF,

Isolevuglandins as a gauge of lipid peroxidation in human tumors

The cellular production of free radicals or reactive oxygen species (ROS) can lead to protein, lipid or DNA modifications and tumor formation. The cellular lipids undergo structural changes through the actions of enzymes (e.g. cyclooxygenases) or free radicals to form a class of compounds called Isolevuglandins (IsoLGs). The recruitment and continued exposure of tissue to ROS and IsoLGs causes increased cell proliferation, mutagenesis, loss of normal cell function and angiogenesis. The elevated concentration of ROS in cancerous tissues suggests that these mediators play an important role in cancer development. We hypothesized that tumors with elevated ROS levels would similarly possess an increased concentration of IsoLGs when compared with normal tissue. Using D11, an ScFv recombinant antibody specific for IsoLGs, we utilized immunohistochemistry to visualize the presence of IsoLG in human tumors compared to normal adjacent tissue (NAT) to the same tumor. We found that IsoLG concentrations were elevated in human breast, colon, kidney, liver, lung, pancreatic and tongue tumor cells when compared to NAT and believe that IsoLGs can be used as a gauge indicative of lipid peroxidation in tumors.

Role of bone marrow-derived CD11c+ dendritic cells in systolic overload-induced left ventricular inflammation, fibrosis and hypertrophy

Inflammatory responses play an important role in the development of left ventricular (LV) hypertrophy and dysfunction. Recent studies demonstrated that increased T-cell infiltration and T-cell activation contribute to LV hypertrophy and dysfunction. Dendritic cells (DCs) are professional antigen-presenting cells that orchestrate immune responses, especially by modulating T-cell function. In this study, we investigated the role of bone marrow-derived CD11c+ DCs in transverse aortic constriction (TAC)-induced LV fibrosis and hypertrophy in mice. We observed that TAC increased the number of CD11c+ cells and the percentage of CD11c+ MHCII+ (major histocompatibility complex class II molecule positive) DCs in the LV, spleen and peripheral blood in mice. Using bone marrow chimeras and an inducible CD11c+ DC ablation model, we found that depletion of bone marrow-derived CD11c+ DCs significantly attenuated LV fibrosis and hypertrophy in mice exposed to 24 weeks of moderate TAC. CD11c+ DC ablation significantly reduced TAC-induced myocardial inflammation as indicated by reduced myocardial CD45+ cells, CD11b+ cells, CD8+ T cells and activated effector CD8+CD44+ T cells in LV tissues. Moreover, pulsing of autologous DCs with LV homogenates from TAC mice promoted T-cell proliferation. These data indicate that bone marrow-derived CD11c+ DCs play a maladaptive role in hemodynamic overload-induced cardiac inflammation, hypertrophy and fibrosis through the presentation of cardiac self-antigens to T cells.