Inflammation, immunity, and hypertension

Can preeclampsia be considered a renal compartment syndrome? A hypothesis and analysis of the literature

The morbidity and mortality associated with preeclampsia is staggering. The physiology of the Page kidney, a condition in which increased intrarenal pressure causes hypertension, appears to provide a unifying framework to explain the complex pathophysiology. Page kidney hypertension is renin-mediated acutely and ischemia-mediated chronically. Renal venous outflow obstruction also causes a Page kidney phenomenon, providing a hypothesis for the increased vulnerability of a subset of women who have what we are hypothesizing is a "renal compartment syndrome" due to inadequate ipsilateral collateral renal venous circulation consistent with well-known variation in normal venous anatomy. Dynamic changes in renal venous anatomy and physiology in pregnancy appear to correlate with disease onset, severity, and recurrence. Since maternal recumbent position is well known to affect renal perfusion and since chronic outflow obstruction makes women vulnerable to the ischemic/inflammatory sequelae, heightened awareness of renal compartment syndrome physiology is critical. The anatomic and physiologic insights provide immediate strategies to predict and prevent preeclampsia with straightforward, low-cost interventions that make renewed global advocacy for pregnant women a realistic goal.

Blood pressure regulation by CD4+ lymphocytes expressing choline acetyltransferase

Blood pressure regulation is known to be maintained by a neuro-endocrine circuit, but whether immune cells contribute to blood pressure homeostasis has not been determined. We previously showed that CD4⁺ T lymphocytes that express choline acetyltransferase (ChAT), which catalyzes the synthesis of the vasorelaxant acetylcholine, relay neural signals. Here we show that these CD4⁺CD44^hiCD62L^lo T helper cells by gene expression are a distinct T-cell population defined by ChAT (CD4 T_ChAT). Mice lacking ChAT expression in CD4⁺ cells have elevated arterial blood pressure, compared to littermate controls. Jurkat T cells overexpressing ChAT (JT_ChAT) decreased blood pressure when infused into mice. Co-incubation of JT_ChAT and endothelial cells increased endothelial cell levels of phosphorylated endothelial nitric oxide synthase, and of nitrates and nitrites in conditioned media, indicating increased release of the potent vasorelaxant nitric oxide. The isolation and characterization of CD4 T_ChAT cells will enable analysis of the role of these cells in hypotension and hypertension, and may suggest novel therapeutic strategies by targeting cell-mediated vasorelaxation.

Gut Microbiota Promote Angiotensin II-Induced Arterial Hypertension and Vascular Dysfunction

Background

The gut microbiome is essential for physiological host responses and development of immune functions. The impact of gut microbiota on blood pressure and systemic vascular function, processes that are determined by immune cell function, is unknown.

Methods and Results

Unchallenged germ‐free mice (GF) had a dampened systemic T helper cell type 1 skewing compared to conventionally raised (CONV‐R) mice. Colonization of GF mice with regular gut microbiota induced lymphoid mRNA transcription of T‐box expression in T cells and resulted in mild endothelial dysfunction. Compared to CONV‐R mice, angiotensin II (AngII; 1 mg/kg per day for 7 days) infused GF mice showed reduced reactive oxygen species formation in the vasculature, attenuated vascular mRNA expression of monocyte chemoattractant protein 1 (MCP‐1), inducible nitric oxide synthase (iNOS) and NADPH oxidase subunit Nox2, as well as a reduced upregulation of retinoic‐acid receptor‐related orphan receptor gamma t (Rorγt), the signature transcription factor for interleukin (IL)‐17 synthesis. This resulted in an attenuated vascular leukocyte adhesion, less infiltration of Ly6G⁺ neutrophils and Ly6C⁺ monocytes into the aortic vessel wall, protection from kidney inflammation, as well as endothelial dysfunction and attenuation of blood pressure increase in response to AngII. Importantly, cardiac inflammation, fibrosis and systolic dysfunction were attenuated in GF mice, indicating systemic protection from cardiovascular inflammatory stress induced by AngII.

Conclusion

Gut microbiota facilitate AngII‐induced vascular dysfunction and hypertension, at least in part, by supporting an MCP‐1/IL‐17 driven vascular immune cell infiltration and inflammation.

Mast cell activation disease and the modern epidemic of chronic inflammatory disease

A large and growing portion of the human population, especially in developed countries, suffers 1 or more chronic, often quite burdensome ailments which either are overtly inflammatory in nature or are suspected to be of inflammatory origin, but for which investigations to date have failed to identify specific causes, let alone unifying mechanisms underlying the multiple such ailments that often afflict such patients. Relatively recently described as a non-neoplastic cousin of the rare hematologic disease mastocytosis, mast cell (MC) activation syndrome-suspected to be of greatly heterogeneous, complex acquired clonality in many cases-is a potential underlying/unifying explanation for a diverse assortment of inflammatory ailments. A brief review of MC biology and how aberrant primary MC activation might lead to such a vast range of illness is presented.

In silico and In vitro evaluation of the anti-inflammatory potential of Centratherum punctatum Cass-A

Centratherum punctatum Cass., a herb belonging to the family Asteraceae has been traditionally used as a curative against diverse disorders like inflammation, tumor, depression, and hypertension. Though the medicinal properties of this plant have been attributed to the presence of flavonoids, glucosides, alkaloids, Vitamin C, etc., the molecular constituents of this plant and of the flavonoids that contribute to its medicinal activity have not been explored yet. This work attempts to evaluate the potential of Centratherum punctatum extract as an anti-inflammatory agent. Ethanolic extracts of Centratherum punctatum analyzed by High Performance Thin Layer Chromatography (HPTLC) and Liquid Chromatography-Mass Spectrometry (LC-MS/MS) identified the presence of the flavones kaempferol, glycoside Isorhamnetin-3-O-rutinoside, and kaempferol-3-glucoside. The plant extract exhibited anti-oxidant property as confirmed by DPPH assay and IC₅₀ value of 271.6 μg/mL during inhibition of protein denaturation, 186.8 μg/mL during RBC membrane stabilization, and 278.2 μg/mL for proteinase inhibition. Membrane stabilizing functions of flavones and flavones glycosides validated the anti-inflammatory potential of the extract. In silico evaluation using a rigorous molecular docking protocol with receptors of Cox2, TNF-α, Interleukin 1β convertase, and Histamine H1 predicted high binding affinity of the isoflavones and isoflavone glycosides of Centratherum punctatum Cass. The interactions have also been shown to compare well with that of known drugs valdecoxib through Gln178, His342, and Gly340, desloratadine (through Lys191 and Thr194) and belnacasin (through Asp288 and Gly287) proven to function through the anti-inflammatory pathway. This work establishes the anti-inflammatory potential of Centratherum punctatum Cass. extract as an alternative to existing therapeutic approach to inflammation through a systematic in silico approach supplementing the findings.

Macrophage Superoxide Anion Production in Essential Hypertension: Associations With Biological and Psychological Cardiovascular Risk Factors

OBJECTIVE

Essential hypertension is an important risk factor for coronary artery disease and its underlying process atherosclerosis, but involved mechanisms are not fully understood. Both macrophages and superoxide anions have been proposed to play a major role in the pathogenesis of atherosclerosis. In the present study, we investigated whether macrophages of individuals with hypertension show higher nicotinamide adenine dinucleotide phosphate oxidase-derived superoxide anion production compared with normotensive individuals. Furthermore, we examined associations between macrophage superoxide anion production and the psychological factors depression and chronic stress independent from hypertension status.

METHODS

We studied 30 hypertensive (mean [standard deviation] = 48.7 [2.4] years) and 30 age-matched normotensive men (mean [standard deviation] = 48.6 [2.4] years). We assessed macrophage superoxide anion production using the WST-1 assay. The assay is based on the chemical reduction of the cell-impermeative tetrazolium salt WST-1 by superoxide anions that are produced by activated human ex vivo isolated monocyte-derived macrophages. We further evaluated whether chronic stress or depressive symptom severity was associated with macrophage superoxide anion production. All analyses were adjusted for potential confounders.

RESULTS

Individuals with hypertension showed higher superoxide anion production compared with normotensive individuals (F(1,58) = 11.56, p = .001). Complementary analyses using mean arterial blood pressure as a continuous measure revealed that higher mean arterial pressure correlated significantly with higher WST-1 reduction (ß = .38, p = .003, ΔR = .145). These results remained significant when controlling for potential confounding influences. Chronic stress was related to higher WST-1 reduction scores, but this association was not statistically significant (ß = .24, p = .067, ΔR = .053); depression levels were not significantly associated with WST-1 reduction scores (p = .24).

CONCLUSIONS

Our results indicate higher macrophage superoxide anion production in individuals with hypertension compared with normotensive individuals. This may suggest a mechanism underlying cardiovascular risk with hypertension.

Hyaluronic Acid in Vascular and Immune Homeostasis during Normal Pregnancy and Preeclampsia

Preeclampsia (PE) is a multisystem pathologic state that clinically manifests itself after the 20th week of pregnancy. It is characterized by high maternal and perinatal morbidity and mortality. According to modern concepts, the impairment of trophoblast invasion into maternal spiral arteries, leading to the development of ischemia in placenta, is considered to be the major pathogenetic factor of PE development. Ischemic lesions initiate the development of a systemic inflammatory response (SIR) and endothelial dysfunction, which is the main cause of the multiple organ failure in PE. Some data has appear indicating the importance of a glycans-forming endothelial glycocalyx and extracellular matrix (ECM) for placenta morphogenesis, as well as their role in the regulation of vascular permeability and vascular tone in hypertension disorders and, in particular, PE. Since intact glycocalyx and ECM are considered to be the major factors that maintain the physiological vascular tone and adequate intercellular interactions, their value in PE pathogenesis is underestimated. This review is focused on hyaluronic acid (HA) as the key glycan providing the organization and stabilization of the ECM and glycocalyx, its distribution in tissues in the case of presence or absence of placental pathology, as well as on the regulatory function of hyaluronic acids of various molecular weights in different physiological and pathophysiological processes. The summarized data will provide a better understanding of the PE pathogenesis, with the main focus on glycopathology.

Transglutaminase is a Critical Link Between Inflammation and Hypertension

Background

The pathogenesis of essential hypertension is multifactorial with different underlying mechanisms contributing to disease. We have recently shown that TNF superfamily member 14 LIGHT (an acronym for homologous to lymphotoxins, exhibits inducible expression, and competes with herpes simplex virus glycoprotein D for herpes virus entry mediator, a receptor expressed by T lymphocytes, also known as TNFSF14) induces hypertension when injected into mice. Research reported here was undertaken to examine the role of transglutaminase (TGase) in LIGHT‐induced hypertension.

Methods and Results

Initial experiments showed that plasma and kidney TGase activity was induced by LIGHT infusion (13.91±2.92 versus 6.75±1.92 mU/mL and 19.86±3.55 versus 12.00±0.97 mU/10 μg) and was accompanied with hypertension (169±7.16 versus 117.17±11.57 mm Hg at day 14) and renal impairment (proteinuria, 61.33±23.21 versus 20.38±9.01 μg/mg; osmolality, 879.57±93.02 versus 1407.2±308.04 mmol/kg). The increase in renal TGase activity corresponded to an increase in RNA for the tissue TGase isoform, termed TG2. Pharmacologically, we showed that LIGHT‐induced hypertension and renal impairment did not occur in the presence of cystamine, a well‐known competitive inhibitor of TGase activity. Genetically, we showed that LIGHT‐mediated induction of TGase, along with hypertension and renal impairment, was dependent on interleukin‐6 and endothelial hypoxia inducible factor‐1α. We also demonstrated that interleukin‐6, endothelial hypoxia inducible factor‐1α, and TGase are required for LIGHT‐induced production of angiotensin receptor agonistic autoantibodies.

Conclusions

Thus, LIGHT‐induced hypertension, renal impairment, and production of angiotensin receptor agonistic autoantibodies require TGase, most likely the TG2 isoform. Our findings establish TGase as a critical link between inflammation, hypertension, and autoimmunity.

Association of serum levels of AngII, KLK1, and ACE/KLK1 polymorphisms with acute myocardial infarction induced by coronary artery stenosis

Introduction:

The study aims to confirm the association of acute myocardial infarction (AMI) with serum angiotensin II (AngII), kallikrein1 (KLK1), and ACE/KLK1 polymorphisms.

Materials and methods:

Serum AngII/KLK1 levels and ACE and KLK1 genotypes were determined in 208 patients with AMI and 216 normal controls. Binary logistic regression was used for data analysis.

Results:

The differences in serum AngII levels were statistically significant between the groups. After adjusting for potential confounding factors, high serum levels of AngII and KLK1 significantly increased the risk of AMI. The individuals with ACE DD and KLK1 GG genotypes significantly increased the risk of AMI compared with those harboring the ACE II and KLK1 AA genotypes (OR = 8.77, 95% CI = 1.74–44.16).

Conclusions:

(1) Increasing the serum levels of AngII increased the risk of AMI. (2) The risk of AMI increased significantly when the serum levels of AngII and KLK1 simultaneously increased. (3) Individuals with the combined genotypes of ACE DD and KLK1 GG showed significantly increased risk of AMI compared with those with the combined genotypes of ACE II and KLK1 AA.

Host factors associated with serologic inflammatory markers assessed using multiplex assays

Chronic systemic inflammation contributes to the development of adverse health conditions, yet the influence of fixed and modifiable risk factors on many serologic biomarkers of inflammation remains largely unknown. Serum concentrations of twenty-three biomarkers, including C-reactive protein (CRP), cytokines (CXCL11, CXCL8, CXCL10, CCL2, CCL13, CCL4, CCL17, CXCL13, IL-10, IL-12p70, IL-6, TNF-α, IL-2, IFN-γ, IL-1β, GM-CSF, BAFF), and soluble immune receptors (sCD14, sIL-2Rα, sCD27, sgp130, sTNF-R2) were measured longitudinally using multiplexed immunometric assays in 250 HIV-uninfected men followed in the Multicenter AIDS Cohort Study (1984-2009). Generalized gamma regression was used to determine the statistical significance of factors associated with each biomarker. After accounting for age, race, and education, and for analysis of multiple biomarkers, higher concentrations of specific individual biomarkers were significantly (P<0.002) associated with hypertension, obesity, hepatitis C infection, stimulant use, and diabetes and lower concentrations with hypercholesterolemia. These associations should be taken into account in epidemiological studies of these biomarkers, and may provide potential targets for disease prevention and treatment.

Renal rescue of dopamine D2 receptor function reverses renal injury and high blood pressure

Dopamine D2 receptor (DRD2) deficiency increases renal inflammation and blood pressure in mice. We show here that long-term renal-selective silencing of Drd2 using siRNA increases renal expression of proinflammatory and profibrotic factors and blood pressure in mice. To determine the effects of renal-selective rescue of Drd2 expression in mice, the renal expression of DRD2 was first silenced using siRNA and 14 days later rescued by retrograde renal infusion of adeno-associated virus (AAV) vector with DRD2. Renal Drd2 siRNA treatment decreased the renal expression of DRD2 protein by 55%, and DRD2 AAV treatment increased the renal expression of DRD2 protein by 7.5- to 10-fold. Renal-selective DRD2 rescue reduced the expression of proinflammatory factors and kidney injury, preserved renal function, and normalized systolic and diastolic blood pressure. These results demonstrate that the deleterious effects of renal-selective Drd2 silencing on renal function and blood pressure were rescued by renal-selective overexpression of DRD2. Moreover, the deleterious effects of 45-minute bilateral ischemia/reperfusion on renal function and blood pressure in mice were ameliorated by a renal-selective increase in DRD2 expression by the retrograde ureteral infusion of DRD2 AAV immediately after the induction of ischemia/reperfusion injury. Thus, 14 days after ischemia/reperfusion injury, the renal expression of profibrotic factors, serum creatinine, and blood pressure were lower in mice infused with DRD2 AAV than in those infused with control AAV. These results indicate an important role of renal DRD2 in limiting renal injury and preserving normal renal function and blood pressure.

Identification of Serum Metabolites Associated With Incident Hypertension in the European Prospective Investigation into Cancer and Nutrition-Potsdam Study

Metabolomics is a promising tool to gain new insights into early metabolic alterations preceding the development of hypertension in humans. We therefore aimed to identify metabolites associated with incident hypertension using measured data of serum metabolites of the European Prospective Investigation Into Cancer and Nutrition (EPIC)-Potsdam study. Targeted metabolic profiling was conducted on serum blood samples of a randomly drawn EPIC-Potsdam subcohort consisting of 135 cases and 981 noncases of incident hypertension, all of them being free of hypertension and not on antihypertensive therapy at the time of blood sampling. Mean follow-up was 9.9 years. A validated set of 127 metabolites was statistically analyzed with a random survival forest backward selection algorithm to identify predictive metabolites of incident hypertension taking into account important epidemiological hypertension risk markers. Six metabolites were identified to be most predictive for the development of hypertension. Higher concentrations of serine, glycine, and acyl-alkyl-phosphatidylcholines C42:4 and C44:3 tended to be associated with higher and diacyl-phosphatidylcholines C38:4 and C38:3 with lower predicted 10-year hypertension-free survival, although visualization by partial plots revealed some nonlinearity in the above associations. The identified metabolites improved prediction of incident hypertension when used together with known risk markers of hypertension. In conclusion, these findings indicate that metabolic alterations occur early in the development of hypertension. However, these alterations are confined to a few members of the amino acid or phosphatidylcholine metabolism, respectively.

Activation of Human T Cells in Hypertension: Studies of Humanized Mice and Hypertensive Humans

Emerging evidence supports an important role for T cells in the genesis of hypertension. Because this work has predominantly been performed in experimental animals, we sought to determine whether human T cells are activated in hypertension. We used a humanized mouse model in which the murine immune system is replaced by the human immune system. Angiotensin II increased systolic pressure to 162 versus 116 mm Hg for sham-treated animals. Flow cytometry of thoracic lymph nodes, thoracic aorta, and kidney revealed increased infiltration of human leukocytes (CD45(+)) and T lymphocytes (CD3(+) and CD4(+)) in response to angiotensin II infusion. Interestingly, there was also an increase in the memory T cells (CD3(+)/CD45RO(+)) in the aortas and lymph nodes. Prevention of hypertension using hydralazine and hydrochlorothiazide prevented the accumulation of T cells in these tissues. Studies of isolated human T cells and monocytes indicated that angiotensin II had no direct effect on cytokine production by T cells or the ability of dendritic cells to drive T-cell proliferation. We also observed an increase in circulating interleukin-17A producing CD4(+) T cells and both CD4(+) and CD8(+) T cells that produce interferon-γ in hypertensive compared with normotensive humans. Thus, human T cells become activated and invade critical end-organ tissues in response to hypertension in a humanized mouse model. This response likely reflects the hypertensive milieu encountered in vivo and is not a direct effect of the hormone angiotensin II.

Hypertension and immunity: mechanisms of T cell activation and pathways of hypertension

PURPOSE OF REVIEW

The role of immune mechanisms to amplify hypertension in patients and animal models has been appreciated for decades. This review briefly summarizes recent studies exploring the mechanistic pathways, whereby the immune system participates in hypertension and renal disease.

RECENT FINDINGS

Emphasis in this review is placed upon recent studies exploring the role of T cell subtypes, newly described mechanisms of T cell activation, the identification of potential neoantigens, and environmental influences on immune cell activation.

SUMMARY

Significant advancements have been made in the search for antigens and pathways responsible for activation of the adaptive immune response, furthering our understanding of the factors contributing to hypertension and potentially leading to the development of new and more effective therapies.

Higher Prevalence of Hypertension in HIV-1-Infected Patients on Combination Antiretroviral Therapy Is Associated With Changes in Body Composition and Prior Stavudine Exposure

BACKGROUND

Individuals infected with human immunodeficiency virus (HIV) have a higher risk of cardiovascular disease, potentially partly mediated by a higher prevalence of hypertension. We therefore examined the prevalence and determinants of hypertension in HIV-1-infected patients compared with appropriate HIV-negative controls.

METHODS

Data from 527 HIV-1-infected and 517 HIV-uninfected participants at the time of enrollment into the ongoing AGEhIV Cohort Study were analyzed. Hypertension was defined as systolic blood pressure ≥140 mmHg, diastolic blood pressure ≥90 mmHg, and/or self-reported use of antihypertensive drugs.

RESULTS

Hypertension prevalence was higher among HIV-1-infected individuals compared with controls (48.2% vs 36.4%; odds ratio [OR], 1.63; 95% confidence interval [CI], 1.27-2.09). In logistic regression models adjusted for age, sex, ethnicity, family history of hypertension, smoking, alcohol use, physical activity, and body mass index, the association between HIV and hypertension remained statistically significant (ORHIV, 1.65; 95% CI, 1.25-2.19), but was attenuated after additional adjustment for waist-to-hip ratio (ORHIV, 1.29; 95% CI, .95-1.76). Among HIV-1-infected individuals, particularly among those with mono/dual nucleoside reverse transcriptase inhibitor therapy prior to combination antiretroviral therapy, stavudine exposure was independently associated with hypertension (ORstavudine, 1.54; 95% CI, 1.04-2.30). This association was attenuated after additional adjustment for either waist-to-hip ratio (ORstavudine, 1.30; 95% CI, .85-1.96) or hip circumference (ORstavudine, 1.40; 95% CI, .93-2.11).

CONCLUSIONS

Our findings suggest that changes in body composition, involving both abdominal obesity and stavudine-induced peripheral lipoatrophy, might contribute to the higher prevalence of hypertension in HIV-1-infected patients.

CLINICAL TRIALS REGISTRATION

NCT01466582.

Interleukin-17A Regulates Renal Sodium Transporters and Renal Injury in Angiotensin II-Induced Hypertension

Angiotensin II-induced hypertension is associated with an increase in T-cell production of interleukin-17A (IL-17A). Recently, we reported that IL-17A(-/-) mice exhibit blunted hypertension, preserved natriuresis in response to a saline challenge, and decreased renal sodium hydrogen exchanger 3 expression after 2 weeks of angiotensin II infusion compared with wild-type mice. In the current study, we performed renal transporter profiling in mice deficient in IL-17A or the related isoform, IL-17F, after 4 weeks of Ang II infusion, the time when the blood pressure reduction in IL-17A(-/-) mice is most prominent. Deficiency of IL-17A abolished the activation of distal tubule transporters, specifically the sodium-chloride cotransporter and the epithelial sodium channel and protected mice from glomerular and tubular injury. In human proximal tubule (HK-2) cells, IL-17A increased sodium hydrogen exchanger 3 expression through a serum and glucocorticoid-regulated kinase 1-dependent pathway. In mouse distal convoluted tubule cells, IL-17A increased sodium-chloride cotransporter activity in a serum and glucocorticoid-regulated kinase 1/Nedd4-2-dependent pathway. In both cell types, acute treatment with IL-17A induced phosphorylation of serum and glucocorticoid-regulated kinase 1 at serine 78, and treatment with a serum and glucocorticoid-regulated kinase 1 inhibitor blocked the effects of IL-17A on sodium hydrogen exchanger 3 and sodium-chloride cotransporter. Interestingly, both HK-2 and mouse distal convoluted tubule 15 cells produce endogenous IL-17A. IL17F had little or no effect on blood pressure or renal sodium transporter abundance. These studies provide a mechanistic link by which IL-17A modulates renal sodium transport and suggest that IL-17A inhibition may improve renal function in hypertension and other autoimmune disorders.

6β-Hydroxytestosterone, a Cytochrome P450 1B1-Testosterone-Metabolite, Mediates Angiotensin II-Induced Renal Dysfunction in Male Mice

6β-Hydroxytestosterone, a cytochrome P450 1B1-derived metabolite of testosterone, contributes to the development of angiotensin II-induced hypertension and associated cardiovascular pathophysiology. In view of the critical role of angiotensin II in the maintenance of renal homeostasis, development of hypertension, and end-organ damage, this study was conducted to determine the contribution of 6β-hydroxytestosterone to angiotensin II actions on water consumption and renal function in male Cyp1b1(+/+) and Cyp1b1(-/-) mice. Castration of Cyp1b1(+/+) mice or Cyp1b1(-/-) gene disruption minimized the angiotensin II-induced increase in water consumption, urine output, proteinuria, and sodium excretion and decreases in urine osmolality. 6β-Hydroxytestosterone did not alter angiotensin II-induced increases in water intake, urine output, proteinuria, and sodium excretion or decreases in osmolality in Cyp1b1(+/+) mice, but restored these effects of angiotensin II in Cyp1b1(-/-) or castrated Cyp1b1(+/+) mice. Cyp1b1 gene disruption or castration prevented angiotensin II-induced renal fibrosis, oxidative stress, inflammation, urinary excretion of angiotensinogen, expression of angiotensin II type 1 receptor, and angiotensin-converting enzyme. 6β-Hydroxytestosterone did not alter angiotensin II-induced renal fibrosis, inflammation, oxidative stress, urinary excretion of angiotensinogen, expression of angiotensin II type 1 receptor, or angiotensin-converting enzyme in Cyp1b1(+/+)mice. However, in Cyp1b1(-/-) or castrated Cyp1b1(+/+) mice, it restored these effects of angiotensin II. These data indicate that 6β-hydroxytestosterone contributes to increased thirst, impairment of renal function, and end-organ injury associated with angiotensin II-induced hypertension in male mice and that cytochrome P450 1B1 could serve as a novel target for treating renal disease and hypertension in male mice.

Interactions of hyperhomocysteinemia and T cell immunity in causation of hypertension

Although hyperhomocysteinemia (HHcy) is an independent risk factor for cardiovascular diseases (CVD), there is a debate on whether HHcy is a risk factor or just a biomarker. Interestingly, homocysteine lowering strategies in humans had very little effect on reducing the cardiovascular risk, as compared with animals; this may suggest heterogeneity in human population and epigenetic alterations. Moreover, there are only few studies that suggest the idea that HHcy contributes to CVD in the presence of other risk factors such as inflammation, a known risk factor for CVD. Elevated levels of homocysteine have been shown to contribute to inflammation. Here, we highlight possible relationships between homocysteine, T cell immunity, and hypertension, and summarize the evidence that suggested these factors act together in increasing the risk for CVD. In light of this new evidence, we further propose that there is a need for evaluation of the causes of HHcy, defective remethylation or defective transsulfuration, which may differentially modulate hypertension progression, not just the homocysteine levels.

Longitudinal genome-wide methylation study of Roux-en-Y gastric bypass patients reveals novel CpG sites associated with essential hypertension

BACKGROUND

Essential hypertension is a significant risk factor for cardiovascular diseases. Emerging research suggests a role of DNA methylation in blood pressure physiology. We aimed to investigate epigenetic associations of promoter related CpG sites to essential hypertension in a genome-wide methylation approach.

METHODS

The genome-wide methylation pattern in whole blood was measured in 11 obese patients before and six months after Roux-en-Y gastric bypass surgery using the Illumina 450 k beadchip. CpG sites located within 1500 bp of the transcriptional start site of adjacent genes were included in our study, resulting in 124 199 probes investigated in the subsequent analysis. Percent changes in methylation states and SBP measured before and six months after surgery were calculated. These parameters were correlated to each other using the Spearman's rank correlation method (Edgeworth series approximation). To further investigate the detected relationship between candidate CpG sites and systolic blood pressure levels, binary logistic regression analyses were performed in a larger and independent cohort of 539 individuals aged 19-101 years to elucidate a relationship between EH and the methylation state in candidate CpG sites.

RESULTS

We identified 24 promoter associated CpG sites that correlated with change in SBP after RYGB surgery (p < 10(-16)). Two of these CpG loci (cg00875989, cg09134341) were significantly hypomethylated in dependency of EH (p < 10(-03)). These results were independent of age, BMI, ethnicity and sex.

CONCLUSIONS

The identification of these novel CpG sites may contribute to a further understanding of the epigenetic regulatory mechanisms underlying the development of essential hypertension.

Cardiac remodelling and RAS inhibition

Risk factors such as hypertension and diabetes are known to augment the activity and tissue expression of angiotensin II (Ang II), the major effector peptide of the renin-angiotensin system (RAS). Overstimulation of the RAS has been implicated in a chain of events that contribute to the pathogenesis of cardiovascular (CV) disease, including the development of cardiac remodelling. This chain of events has been termed the CV continuum. The concept of CV disease existing as a continuum was first proposed in 1991 and it is believed that intervention at any point within the continuum can modify disease progression. Treatment with antihypertensive agents may result in regression of left ventricular hypertrophy, with different drug classes exhibiting different degrees of efficacy. The greatest decrease in left ventricular mass is observed following treatment with angiotensin converting enzyme inhibitors (ACE-Is), which inhibit Ang II formation. Although ACE-Is and angiotensin receptor blockers (ARBs) provide significant benefits in terms of CV events and stroke, mortality remains high. This is partly due to a failure to completely suppress the RAS, and, as our knowledge has increased, an escape phenomenon has been proposed whereby the human sequence of the 12 amino acid substrate angiotensin-(1-12) is converted to Ang II by the mast cell protease, chymase. Angiotensin-(1-12) is abundant in a wide range of organs and has been shown to increase blood pressure in animal models, an effect abolished by the presence of ACE-Is or ARBs. This review explores the CV continuum, in addition to examining the influence of the RAS. We also consider novel pathways within the RAS and how new therapeutic approaches that target this are required to further reduce Ang II formation, and so provide patients with additional benefits from a more complete blockade of the RAS.

Hypertension Among HIV-infected Patients in Clinical Care, 1996-2013

BACKGROUND

Persons infected with human immunodeficiency virus (HIV) are at higher risk for major cardiovascular disease (CVD) events than uninfected persons. Understanding the epidemiology of major traditional CVD risk determinants, particularly hypertension, in this population is needed.

METHODS

The study population included HIV-infected patients participating in the UNC CFAR HIV Clinical Cohort from 1996 to 2013. Annual incidence rates of hypertension were calculated. Multivariable Poisson models were fit to identify factors associated with incident hypertension.

RESULTS

3141 patients contributed 21 956 person-years (PY) of follow-up. Overall, 57% patients were black, 28% were women, and the median age was 35 years. Hypertension age-standardized incidence rates increased from 1.68 cases per 100 PYs in 1996 to 5.35 cases per 100 PYs in 2013 (P < .001). In adjusted analyses, hypertension rates were higher among obese patients (incidence rate ratio [IRR] 1.70, 95% confidence interval [CI], 1.43-2.02), and those with diabetes mellitus (IRR 1.44, 95% CI, 1.14-1.83) and renal insufficiency (IRR 1.36, 95% CI, 1.16-1.61), but lower among patients with a CD4 nadir of ≥500 cells/mm(3) (IRR 0.73, 95% CI, .53-1.01).

CONCLUSIONS

The incidence of hypertension increased from 1996 to 2013, alongside increases in traditional hypertension risk determinants. Notably, HIV-related immunosuppression and ongoing viral replication may contribute to an increased hypertension risk. Aggressive CVD risk factor management, early HIV diagnosis, linkage to care, antiretroviral therapy initiation, and durable viral suppression, will be important components of a comprehensive primary CVD prevention strategy in HIV-infected persons.

Hypertension as an autoimmune and inflammatory disease

Hypertension that is considered idiopathic is called essential hypertension and accordingly has no clear culprit for its cause. However, basic research and clinical studies in recent years have expanded our understanding of the mechanisms underlying the development of essential hypertension. Of these, increased oxidative stress, both in the kidney and arterial wall, closely coupled with inflammatory infiltration now appear to have a prominent role. Discovery of regulatory and interleukin-17-producing T cells has enabled us to better understand the mechanism by which inflammation and autoimmunity, or autoinflammation, lead to the development of hypertension. Despite achieving considerable progress, the intricate interactions between oxidative stress, the immune system and the development of hypertension remain to be fully elucidated. In this review, we summarize recent developments in the pathophysiology of hypertension with a focus on the oxidant stress-autoimmunity-inflammation interaction.

The Association Between Glycosylation of Immunoglobulin G and Hypertension: A Multiple Ethnic Cross-Sectional Study

More than half of all known proteins, and almost all membrane and extra-cellular proteins have oligosaccharide structures or glycans attached to them. Defects in glycosylation pathways are directly involved in at least 30 severe human diseases.A multiple center cross-sectional study (China, Croatia, and Scotland) was carried out to investigate the possible association between hypertension and IgG glycosylation. A hydrophilic interaction chromatography of fluorescently labeled glycans was used to analyze N-glycans attached to IgG in plasma samples from a total of 4757 individuals of Chinese Han, Croatian, and Scottish ethnicity.Five glycans (IgG with digalactosylated glycans) significantly differed in participants with prehypertension or hypertension compared to those with normal blood pressure, while additional 17 glycan traits were only significantly differed in participants with hypertension compared to those of normal blood pressure. These glycans were also significant correlated with systolic blood pressure (SBP) or diastolic blood pressure (DBP).The present study demonstrated for the 1st time an association between hypertension and IgG glycome composition. These findings suggest that the individual variation in N-glycosylation of IgG contributes to pathogenesis of hypertension, presumably via its effect on pro- and/or anti-inflammatory pathways.

The effects of telmisartan on the nuclear factor of activated T lymphocytes signalling pathway in hypertensive patients

HYPOTHESIS

Previous studies provide links between the nuclear factor of activated T lymphocytes (NFAT) signalling pathway and the development of hypertension. Our preliminary studies indicate that telmisartan can block Kv1.3 potassium channels and effectively inhibit potassium current densities, along with Kv1.3 mRNA and protein expression levels. This paper aims to investigate whether telmisartan has an inhibitory effect on the NFAT signalling pathway after activation and proliferation of peripheral blood T lymphocytes in Kazakh patients with essential hypertension (EH) from Xinjiang, China.

MATERIALS AND METHODS

T lymphocytes were isolated using the immunomagnetic cell sorting method (MACS). The mRNA expression of NFATc1, IL-6 and TNF-α was measured by quantitative polymerase chain reaction (qRT-PCR) and relative protein levels were evaluated by Western blot. T cell samples from 50 hypertensive Kazakh patients from Xinjiang were randomly divided into control, telmisartan, cyclosporin A (CsA), VIVIT, and 4-aminopytidine (4-AP) groups. Peripheral blood T lymphocytes were first activated and proliferated in vitro, then incubated for 48 h under different treatment conditions before determination of protein and mRNA expression of NFATc1, IL-6, and TNF-α by Western blot and qRT-PCR analyses, respectively.

RESULTS

There were no significant differences in cardiovascular risk factors among the patients with samples assigned to the five groups (p > 0.05). Expression of NFATc1, IL-6, and TNF-α mRNA and protein was significantly reduced in T lymphocytes in all treatment groups (telmisartan, CsA, VIVIT, and 4-AP) compared with controls.

CONCLUSIONS

Antihypertensive function and inhibitory effects of telmisartan on the T lymphocyte NFAT signalling pathway are unlikely to affect the normal immune function of hypertensive patients. Telmisartan may exert anti-inflammatory effects by inhibition of the NFAT signalling pathway in the T lymphocytes of hypertensive patients.

CD70 Exacerbates Blood Pressure Elevation and Renal Damage in Response to Repeated Hypertensive Stimuli

RATIONALE

Accumulating evidence supports a role of adaptive immunity and particularly T cells in the pathogenesis of hypertension. Formation of memory T cells, which requires the costimulatory molecule CD70 on antigen-presenting cells, is a cardinal feature of adaptive immunity.

OBJECTIVE

To test the hypothesis that CD70 and immunologic memory contribute to the blood pressure elevation and renal dysfunction mediated by repeated hypertensive challenges.

METHODS AND RESULTS

We imposed repeated hypertensive challenges using either N(ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME)/high salt or repeated angiotensin II stimulation in mice. During these challenges effector memory T cells (T(EM)) accumulated in the kidney and bone marrow. In the L-NAME/high-salt model, memory T cells of the kidney were predominant sources of interferon-γ and interleukin-17A, known to contribute to hypertension. L-NAME/high salt increased macrophage and dendritic cell surface expression of CD70 by 3- to 5-fold. Mice lacking CD70 did not accumulate T(EM) cells and did not develop hypertension to either high salt or the second angiotensin II challenge and were protected against renal damage. Bone marrow-residing T(EM) cells proliferated and redistributed to the kidney in response to repeated salt feeding. Adoptively transferred T(EM) cells from hypertensive mice homed to the bone marrow and spleen and expanded on salt feeding of the recipient mice.

CONCLUSIONS

Our findings illustrate a previously undefined role of CD70 and long-lived T(EM) cells in the development of blood pressure elevation and end-organ damage that occur on delayed exposure to mild hypertensive stimuli. Interventions to prevent repeated hypertensive surges could attenuate formation of hypertension-specific T(EM) cells.

Understanding mechanisms of hypertension in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder that predominately affects women of reproductive age. Hypertension is an important cardiovascular risk factor that is prevalent in this patient population. Despite the high incidence of hypertension in women with SLE, the pathophysiological mechanisms underlying the development of hypertension remain poorly understood. This review will focus on disease-related factors, including inflammation, autoantibodies, and sex hormones that may contribute to hypertension in patients with SLE. In addition, we will highlight studies performed by our laboratory using the female NZBWF1 (F1 hybrid of New Zealand Black and New Zealand White strains) mouse model, a spontaneous model of SLE that mimics human disease and develops hypertension and renal injury. Specifically, using female NZBWF1 mice, we have demonstrated that multiple factors contribute to the pathogenesis of hypertension, including the inflammatory cytokine, tumor necrosis factor (TNF)-α, oxidative stress, as well as B-cell hyperactivity and autoantibody production.

Glucocorticoid-induced fetal origins of adult hypertension: Association with epigenetic events

Hypertension is a predominant risk factor for cardiovascular diseases and a major health care burden. Accumulating epidemiological and experimental evidence suggest that adult-onset hypertension may have its origins during early development. Upon exposure to glucocorticoids, the fetus develops hypertension, and the offspring may be programmed to continue the hypertensive trajectory into adulthood. Elevated oxidative stress and deranged nitric oxide system are not only hallmarks of adult hypertension but are also observed earlier in life. Endothelial dysfunction and remodeling of the vasculature, which are robustly associated with increased incidence of hypertension, are likely to have been pre-programmed during fetal life. Apparently, genomic, non-genomic, and epigenomic factors play a significant role in the development of hypertension, including glucocorticoid-driven effects on blood pressure. In this review, we discuss the involvement of the aforementioned participants in the pathophysiology of hypertension and suggest therapeutic opportunities for targeting epigenome modifiers, potentially for personalized medicine.

Systemic T Cells and Monocyte Characteristics in Patients with Denture Stomatitis

PURPOSE

Chronic inflammatory disorders of the oral cavity, such as periodontitis, were recently linked to systemic immune activation. Since fungal oral infections have not yet been studied in this respect, the aim of our study is to determine whether the local inflammation caused by oral fungal infection of the palatal tissue (denture stomatitis-DS) is associated with the systemic inflammatory response. This question is becoming essential as the population ages.

MATERIALS AND METHODS

Peripheral blood of DS patients (n = 20) and control patients (n = 24) was assessed with flow cytometry to determine lymphocyte and monocyte profiles. Intracellular cytometric analysis was carried out to establish cytokine production by T cells. DS was diagnosed based on clinical symptoms of DS such as swelling and redness of oral mucosa, confirmed by microbiological swabs for fungal colonization with Candida species. The control group was recruited from denture users without clinical and microbiological signs of oral infections.

RESULTS

Percentages of peripheral lymphocytes, T cells, monocytes, and their subpopulations were similar in both studied groups. The exception was median percentages of CD25+ T cell subsets, which were significantly lower in DS patients than in control subjects. This reduction was observed in both CD4 T cell subset (16.7% and 28.1%; p = 0.0006) and CD8 T cell subset (4.6% and 7.0%; p = 0.007) CONCLUSIONS: While DS and associated local fungal infection do not overtly affect activation of monocytes or lymphocytes, the number of CD 25+ T cells is significantly lower in the DS patients, possibly indicating limited potential for the infection clearance in denture-using aging patients.

Cytosolic Phospholipase A2α Is Essential for Renal Dysfunction and End-Organ Damage Associated With Angiotensin II-Induced Hypertension

BACKGROUND

The kidney plays an important role in regulating blood pressure (BP). cPLA2α in the kidney is activated by various agents including angiotensin II (Ang II) and selectively releases arachidonic acid (AA) from tissue lipids, generating pro- and antihypertensive eicosanoids. Since activation of cPLA2α is the rate-limiting step in AA release, this study was conducted to determine its contribution to renal dysfunction and end-organ damage associated with Ang II-induced hypertension.

METHODS

cPLA2α(+/+) and cPLA2α(-/-) mice were infused with Ang II (700 ng/ kg/min) or its vehicle for 13 days. Mice were placed in metabolic cages to monitor their food and water intake, and urine was collected and its volume was measured. Doppler imaging was performed to assess renal hemodynamics. On the 13th day of Ang II infusion, mice were sacrificed and their tissues and blood collected for further analysis.

RESULTS

Ang II increased renal vascular resistance, water intake, and urine output and Na(+) excretion, decreased urine osmolality, and produced proteinuria in cPLA2α(+/+) mice. Ang II also caused accumulation of F4/80(+) macrophages and CD3(+) T cells and renal fibrosis, and increased oxidative stress in the kidneys of cPLA2α(+/+) mice. All these effects of Ang II were minimized in cPLA2α(-/-) mice.

CONCLUSION

cPLA2α contributes to renal dysfunction, inflammation, and end-organ damage, most likely via the action of pro-hypertensive eicosanoids and increased oxidative stress associated with Ang II-induced hypertension. Thus, cPLA2α could serve as a potential therapeutic target for treating renal dysfunction and end-organ damage in hypertension.

Primary hypertension is a disease of premature vascular aging associated with neuro-immuno-metabolic abnormalities

There is an increasing amount of data indicating that primary hypertension (PH) is not only a hemodynamic phenomenon but also a complex syndrome involving abnormal fat tissue distribution, over-activity of the sympathetic nervous system (SNS), metabolic abnormalities, and activation of the immune system. In children, PH usually presents with a typical phenotype of disturbed body composition, accelerated biological maturity, and subtle immunological and metabolic abnormalities. This stage of the disease is potentially reversible. However, long-lasting over-activity of the SNS and immuno-metabolic alterations usually lead to an irreversible stage of cardiovascular disease. We describe an intermediate phenotype of children with PH, showing that PH is associated with accelerated development, i.e., early premature aging of the immune, metabolic, and vascular systems. The associations and determinants of hypertensive organ damage, the principles of treatment, and the possibility of rejuvenation of the cardiovascular system are discussed.

Angiotensin II Regulation of Proliferation, Differentiation, and Engraftment of Hematopoietic Stem Cells

Emerging evidence indicates that differentiation and mobilization of hematopoietic cell are critical in the development and establishment of hypertension and hypertension-linked vascular pathophysiology. This, coupled with the intimate involvement of the hyperactive renin-angiotensin system in hypertension, led us to investigate the hypothesis that chronic angiotensin II (Ang II) infusion affects hematopoietic stem cell (HSC) regulation at the level of the bone marrow. Ang II infusion resulted in increases in hematopoietic stem/progenitor cells (83%) and long-term HSC (207%) in the bone marrow. Interestingly, increases of HSCs and long-term HSCs were more pronounced in the spleen (228% and 1117%, respectively). Furthermore, we observed higher expression of C-C chemokine receptor type 2 in these HSCs, indicating there was increased myeloid differentiation in Ang II-infused mice. This was associated with accumulation of C-C chemokine receptor type 2(+) proinflammatory monocytes in the spleen. In contrast, decreased engraftment efficiency of GFP(+) HSC was observed after Ang II infusion. Time-lapse in vivo imaging and in vitro Ang II pretreatment demonstrated that Ang II induces untimely proliferation and differentiation of the donor HSC resulting in diminished HSC engraftment and bone marrow reconstitution. We conclude that (1) chronic Ang II infusion regulates HSC proliferation, mediated by angiotensin receptor type 1a, (2) Ang II accelerates HSC to myeloid differentiation resulting in accumulation of C-C chemokine receptor type 2(+) HSCs and inflammatory monocytes in the spleen, and (3) Ang II impairs homing and reconstitution potentials of the donor HSCs. These observations highlight the important regulatory roles of Ang II on HSC proliferation, differentiation, and engraftment.

Dopamine D2 receptors' effects on renal inflammation are mediated by regulation of PP2A function

Lack or downregulation of the dopamine D2 receptor (D2R) results in increased renal expression of injury markers and proinflammatory factors that is independent of a blood pressure increase. This study aimed to determine the mechanisms involved in the regulation of renal inflammation by D2Rs. Silencing D2Rs in mouse renal proximal tubule cells increased the expression of the proinflammatory TNF-α, monocyte chemoattractant protein-1 (MCP-1), and IL-6. D2R downregulation also increased Akt phosphorylation and activity, and glycogen synthase kinase-3β (GSK3β) phosphorylation and cyclin D1 expression, downstream targets of Akt; however. phosphatidylinositol 3-kinase (PI3K) activity was not affected. Conversely, D2R stimulation decreased Akt and GSK3β phosphorylation and cyclin D1 expression. Increased phospho-Akt, in the absence of increased PI3K activity, may result from decreased Akt dephosphorylation. Inhibition of protein phosphatase 2A (PP2A) with okadaic acid reproduced the effects of D2R downregulation on Akt, GSK3β, and cyclin D1. The PP2A catalytic subunit and regulatory subunit PPP2R2C coimmunoprecipitated with the D2R. Basal phosphatase activity and the expression of PPP2R2C were decreased by D2R silencing that also blunted the increase in phosphatase activity induced by D2R stimulation. Similarly, silencing PPP2R2C also increased the phosphorylation of Akt and GSK3β. Moreover, downregulation of PPP2R2C resulted in increased expression of TNF-α, MCP-1, and IL-6, indicating that decreased phosphatase activity may be responsible for the D2R effect on inflammatory factors. Indeed, the increase in NF-κB reporter activity induced by D2R silencing was blunted by increasing PP2A activity with protamine. Our results show that D2R controls renal inflammation, at least in part, by modulation of the Akt pathway through effects on PP2A activity/expression.

Dysregulation of T cell subsets in the pathogenesis of hypertension

Essential hypertension (EH) and its complications have had a severe impact on public health. However, the underlying mechanisms of the pathogenesis of EH remain largely unknown. Recent investigations, predominantly in rats and mice, have provided evidence that dysregulation of distinct functions of T lymphocyte subsets is a potentially important mechanism in the pathogenesis of hypertension. We critically reviewed recent findings and propose an alternative explanation on the understanding of dysfunctional T lymphocyte subsets in the pathogenesis of hypertension. The hypothesis is that hypertensive stimuli, directly and indirectly, increase local IL-6 levels in the cardiovascular system and kidney, which may promote peripheral imbalance in the differentiation and ratio of Th17 and T regulatory cells. This results in increased IL-17 and decreased IL-10 in perivascular adipose tissue and adventitia contributing to the development of hypertension in experimental animal models. Further investigation in the field is warranted to inform new translational advances that will promote to understand the pathogenesis of EH and develop novel approaches to prevent and treat EH.

Interrelationship Between Periapical Lesion and Systemic Metabolic Disorders

BACKGROUND

Periapical periodontitis, also known as periapical lesion, is a common dental disease, along with periodontitis (gum disease). Periapical periodontitis is a chronic inflammatory disease, caused by endodontic infection, and its development is regulated by the host immune/inflammatory response. Metabolic disorders, which are largely dependent on life style such as eating habits, have been interpreted as a "metabolically-triggered" low-grade systemic inflammation and may interact with periapical periodontitis by triggering immune modulation. The host immune system is therefore considered the common fundamental mechanism of both disease conditions.

METHOD

We have reviewed >200 articles to discuss the interrelationship between periapical lesions and metabolic disorders including type 2 diabetes mellitus, hypertension, and non-alcoholic fatty liver diseases (NAFLD), and their common pathological background in immunology/osteoimmunology and cytokine biology.

RESULTS

An elevated inflammatory state caused by metabolic disorders can impact the clinical outcome of periapical lesions and interfere with wound healing after endodontic treatment. Although additional well-designed clinical studies are needed, periapical lesions appear to affect insulin sensitivity and exacerbate non-alcoholic steatohepatitis.

CONCLUSION

Immune regulatory cytokines produced by various cell types, including immune cells and adipose tissue, play an important role in this interrelationship.

Sympathetic-mediated activation versus suppression of the immune system: consequences for hypertension

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.

20-HETE Activates the Transcription of Angiotensin-Converting Enzyme via Nuclear Factor-κB Translocation and Promoter Binding

Increased vascular 20-hydroxyeicosatetraenoic acid (20-HETE), a cytochrome P450 arachidonic acid metabolite, promotes vascular dysfunction, injury, and hypertension that is dependent, in part, on the renin angiotensin system (RAS). We have shown that, in human microvascular endothelial cells, 20-HETE increases angiotensin-converting enzyme (ACE) mRNA, protein, and ACE activity via an epidermal growth factor receptor (EGFR)/tyrosine kinase/mitogen-activated protein kinase (MAPK)/inhibitor of κB kinase (IKK)β-mediated signaling pathway. In this work, we show that, similar to epidermal growth factor (EGF), 20-HETE (10 nM) activates EGFR by stimulating tyrosine phosphorylation; however, unlike 20-HETE, EGF does not induce ACE expression, and pretreatment with a neutralizing antibody against EGF does not prevent the 20-HETE-mediated ACE induction. Inhibition of nuclear factor κB (NF-κB) activation prevented the 4.58-fold (±0.78; P < 0.05) 20-HETE-mediated induction of ACE. The 20-HETE increased NF-κB-binding activity in nuclear extracts and the activity of both the somatic and germinal ACE promoters by 4.37-fold (±0.18; P < 0.05) and 2.53-fold (± 0.24; P < 0.05), respectively. The 20-HETE-stimulated ACE promoter activity was abrogated by the 20-HETE antagonist 20-hydroxy-6,15-eicosadienoic acid and by inhibitors of EGFR, MAPK, IKKβ, and NF-κB activation. Sequence analysis demonstrated the presence of two and one putative NF-κB binding sites on the human somatic and germinal ACE promoters, respectively. Chromatin immunoprecipitation assay indicated that 20-HETE stimulates the translocation and subsequent binding of NF-κB to each of the putative binding sites (S1, 3.43 ± 0.3-fold enrichment versus vehicle; S2, 3.72 ± 0.68-fold enrichment versus vehicle; S3, 3.20 ± 0.18-fold enrichment versus vehicle; P < 0.05). This is the first study to identify NF-κB as a transcriptional factor for ACE and to implicate a distinct EGFR/MAPK/IKK/NF-κB signaling cascade underlying 20-HETE-mediated transcriptional activation of ACE mRNA and stimulation of ACE activity.

Pentosan polysulfate preserves renal microvascular P2X1 receptor reactivity and autoregulatory behavior in DOCA-salt hypertensive rats

Inflammation contributes to ANG II-associated impairment of renal autoregulation and microvascular P2X1 receptor signaling, but its role in renal autoregulation in mineralocorticoid-induced hypertension is unknown. Autoregulatory behavior was assessed using the blood-perfused juxtamedullary nephron preparation. Hypertension was induced in uninephrectomized control rats (UNx) by subcutaneous implantation of a DOCA pellet plus administration of 1% NaCl in the drinking water (DOCA-salt) for 3 wk. DOCA-salt rats developed hypertension that was unaltered by anti-inflammatory treatment with pentosan polysulfate (DOCA-salt+PPS) but was suppressed with "triple therapy" (hydrochlorothiazide, hydralazine, and reserpine; DOCA-salt+TTx). Baseline arteriolar diameters were similar across all groups. UNx rats exhibited pressure-dependent vasoconstriction with diameters declining to 69 ± 2% of control at 170 mmHg, indicating intact autoregulation. DOCA-salt treatment significantly blunted this pressure-mediated vasoconstriction. Diameters remained between 91 ± 4 and 98 ± 3% of control over 65-170 mmHg, indicating impaired autoregulation. In contrast, pressure-mediated vasoconstriction was preserved in DOCA-salt+PPS and DOCA-salt+TTx rats, reaching 77 ± 7 and 75 ± 3% of control at 170 mmHg, respectively. ATP is required for autoregulation via P2X1 receptor activation. ATP- and β,γ-methylene ATP (P2X1 receptor agonist)-mediated vasoconstriction were markedly attenuated in DOCA-salt rats compared with UNx (P < 0.05), but significantly improved by PPS or TTx (P < 0.05 vs. DOCA-salt) treatment. Arteriolar responses to adenosine and UTP (P2Y2 receptor agonist) were unaffected by DOCA-salt treatment. PPS and TTx significantly reduced MCP-1 and protein excretion in DOCA-salt rats. These results support the hypothesis that hypertension triggers inflammatory cascades but anti-inflammatory treatment preserves renal autoregulation in DOCA-salt rats, most likely by normalizing renal microvascular reactivity to P2X1 receptor activation.

Sex, the brain and hypertension: brain oestrogen receptors and high blood pressure risk factors

Hypertension is a major contributor to worldwide morbidity and mortality rates related to cardiovascular disease. There are important sex differences in the onset and rate of hypertension in humans. Compared with age-matched men, premenopausal women are less likely to develop hypertension. However, after age 60, the incidence of hypertension increases in women and even surpasses that seen in older men. It is thought that changes in levels of circulating ovarian hormones as women age may be involved in the increase in hypertension in older women. One of the key mechanisms involved in the development of hypertension in both men and women is an increase in sympathetic nerve activity (SNA). Brain regions important for the regulation of SNA, such as the subfornical organ, the paraventricular nucleus and the rostral ventral lateral medulla, also express specific subtypes of oestrogen receptors. Each of these brain regions has also been implicated in mechanisms underlying risk factors for hypertension such as obesity, stress and inflammation. The present review brings together evidence that links actions of oestrogen at these receptors to modulate some of the common brain mechanisms involved in the ability of hypertensive risk factors to increase SNA and blood pressure. Understanding the mechanisms by which oestrogen acts at key sites in the brain for the regulation of SNA is important for the development of novel, sex-specific therapies for treating hypertension.

An Evolutionary Perspective of Nutrition and Inflammation as Mechanisms of Cardiovascular Disease

When cardiovascular diseases are viewed from an evolutionary biology perspective, a heightened thrifty and an inflammatory design could be their mechanisms. Human ancestors confronted a greater infectious load and were subjected to the selection for proinflammatory genes and a strong inflammatory function. Ancestors also faced starvation periods that pressed for a thrifty genotype which caused fat accumulation. The pressure of sustaining gluconeogenesis during periods of poor nourishment selected individuals with insulin resistance. Obesity induces a proinflammatory state due to the secretion of adipokines which underlie cardiometabolic diseases. Our actual lifestyle needs no more of such proinflammatory and thrifty genotypes and these ancestral genes might increase predisposition to diseases. Risk factors for atherosclerosis and diabetes are based on inflammatory and genetic foundations that can be accounted for by excess fat. Longevity has also increased in recent times and is related to a proinflammatory response with cardiovascular consequences. If human ancestral lifestyle could be recovered by increasing exercise and adapting a calorie restriction diet, obesity would decrease and the effects on chronic low-grade inflammation would be limited. Thereby, the rates of both atherosclerosis and diabetes could be reduced.

Effect of protein arginine methyltransferase-1 inhibition on hypoxia-induced vasoconstriction

Hypoxia is defined as a decrease in the oxygen supply to a level below physiological levels which is insufficient to maintain cellular function, in the presence of unrestricted coronary inflow. It is one of the leading causes of global mortality and morbidity, due to its association with the pathology of cancer, cardiovascular disease and stroke. The common feature in these pathologies is the limitation of oxygen availability that participates in the development of these conditions. The pulmonary response to hypoxia, when hypoxia is localized, is hypoxic pulmonary vasoconstriction (HPV). HPV is a physiological and self-regulatory mechanism by which pulmonary capillary blood flow is automatically adjusted to alveolar ventilation for maintaining the optimal balance of ventilation and perfusion. In pathological conditions, HPV occurs as an acute episode during progressive critical illness or as a sustained response with vascular remodeling and pulmonary hypertension. Inspite of the hypoxia-induced shift in the redox status to a more oxidized state, the endothelium-dependent mediators of HPV that cause vasoconstrictor response to hypoxia include nitric oxide (NO), endothelin-1 and angiotensin-II. Indeed, in chronic hypoxia, due to the enhanced reactive oxygen species (ROS) generation, inhibition of endothelial nitric oxide synthase (eNOS) activity and reduced nitric oxide (NO) production there is an imbalance in the vasoconstriction-vasodilation status toward constriction. It is our hypothesis that, in hypoxic stress, a key player in initiating this imbalance is the enzyme, protein arginine methyltransferase-1 (PRMT1) which indirectly affects eNOS activity by increased production of asymmetric dimethylarginine (ADMA), a NOS-inhibitor. Thus, pharmacological inhibition of PRMT1 should restore the cellular and vascular homeostasis in hypoxic conditions.

Blood Neutrophil to Lymphocyte Ratio as a Predictor of Hypertension

BACKGROUND

Hypertension is a significant global public health challenge. Low-grade inflammation is known to facilitate the development of essential hypertension and target-organ hypertensive damage. Neutrophil to lymphocyte ratio (NLR) is a simple and reliable indicator of inflammation that may also be useful in the prediction of hypertension.

METHODS

Participants were recruited from Tianjin Medical University's General Hospital-Health Management Centre. A total of 28,850 initially hypertension-free subjects were followed from 2007 to 2013. Adjusted Cox proportional hazards regression models were used to assess relationships between NLR categories and incidence of hypertension.

RESULTS

During the ~6-year follow-up period (median duration of follow-up (interquartile range): 2.63 (2.58-2.68)), 1,824 subjects developed hypertension. The hazard ratios of hypertension incidence were evaluated in increasing NLR quintiles. Compared with participants with the lowest NLR levels, the multivariable-adjusted hazard ratios (95% confidence interval) of hypertension were related to increasing NLR quintiles and were as follows: 1.08 (0.92, 1.26), 0.97 (0.83, 1.14), 1.10 (0.94, 1.28), and 1.23 (1.06, 1.43), respectively (P for trend < 0.01). Similar results also were observed in the white blood cell and neutrophil counts, but not lymphocyte counts.

CONCLUSIONS

The study is the first to show the elevated NLR levels significantly correlate with an increased risk of developing hypertension. This result may be useful in elucidating the mechanism underlying the development of hypertension. New therapeutic approaches aimed at inflammation might be proposed to control hypertension and hypertensive damage.

Is immune system-related hypertension associated with ovarian hormone deficiency?

NEW FINDINGS

What is the topic of this review? This review summarizes recent data on the role of ovarian hormones and sex in inflammation-related hypertension. What advances does it highlight? The adaptive immune system has recently been implicated in the development of hypertension in males but not in females. The role of the immune system in the development of hypertension in women and its relationship to ovarian hormone production are highlighted. The immune system is known to contribute to the development of high blood pressure in males. However, the role of the immune system in the development of high blood pressure in females and the role of ovarian hormones has only recently begun to be studied. In animal studies, both the sex of the host and the T cell are critical biological determinants of susceptibility and resistance to hypertension induced by angiotensin II. In women, natural menopause is known to result in significant changes in the expression of genes regulating the immune system. Likewise, in animal models, ovariectomy results in hypertension and an upregulation in T-cell tumour necrosis factor-α-related genes. Oestrogen replacement results in decreases in inflammatory genes in the brain regions involved in blood pressure regulation. Together, these studies suggest that the response of the adaptive immune system to ovarian hormone deficiency is a significant contributor to hypertension in women.

Macrophages dictate the progression and manifestation of hypertensive heart disease

BACKGROUND

Inflammation has been implicated in the initiation, progression and manifestation of hypertensive heart disease. We sought to determine the role of monocytes/macrophages in hypertension and pressure overload induced left ventricular (LV) remodeling.

METHODS AND RESULTS

We used two models of LV hypertrophy (LVH). First, to induce hypertension and LVH, we fed Sabra salt-sensitive rats with a high-salt diet. The number of macrophages increased in the hypertensive hearts, peaking at 10 weeks after a high-salt diet. Surprisingly, macrophage depletion, by IV clodronate (CL) liposomes, inhibited the development of hypertension. Moreover, macrophage depletion reduced LVH by 17% (p<0.05), and reduced cardiac fibrosis by 75%, compared with controls (p=0.001). Second, to determine the role of macrophages in the development and progression of LVH, independent of high-salt diet, we depleted macrophages in mice subjected to transverse aortic constriction and pressure overload. Significantly, macrophage depletion, for 3 weeks, attenuated LVH: a 12% decrease in diastolic and 20% in systolic wall thickness (p<0.05), and a 13% in LV mass (p=0.04), compared with controls. Additionally, macrophage depletion reduced cardiac fibrosis by 80% (p=0.006). Finally, macrophage depletion down-regulated the expression of genes associated with cardiac remodeling and fibrosis: transforming growth factor beta-1 (by 80%) collagen type III alpha-1 (by 71%) and atrial natriuretic factor (by 86%).

CONCLUSIONS

Macrophages mediate the development of hypertension, LVH, adverse cardiac remodeling, and fibrosis. Macrophages, therefore, should be considered as a therapeutic target to reduce the adverse consequences of hypertensive heart disease.