Vanessa Fontana

DC isoketal-modified proteins activate T cells and promote hypertension

Oxidative damage and inflammation are both implicated in the genesis of hypertension; however, the mechanisms by which these stimuli promote hypertension are not fully understood. Here, we have described a pathway in which hypertensive stimuli promote dendritic cell (DC) activation of T cells, ultimately leading to hypertension. Using multiple murine models of hypertension, we determined that proteins oxidatively modified by highly reactive γ-ketoaldehydes (isoketals) are formed in hypertension and accumulate in DCs. Isoketal accumulation was associated with DC production of IL-6, IL-1β, and IL-23 and an increase in costimulatory proteins CD80 and CD86. These activated DCs promoted T cell, particularly CD8+ T cell, proliferation; production of IFN-γ and IL-17A; and hypertension. Moreover, isoketal scavengers prevented these hypertension-associated events. Plasma F2-isoprostanes, which are formed in concert with isoketals, were found to be elevated in humans with treated hypertension and were markedly elevated in patients with resistant hypertension. Isoketal-modified proteins were also markedly elevated in circulating monocytes and DCs from humans with hypertension. Our data reveal that hypertension activates DCs, in large part by promoting the formation of isoketals, and suggest that reducing isoketals has potential as a treatment strategy for this disease.

Increased arterial stiffness in resistant hypertension is associated with inflammatory biomarkers

Abstract Background. Increased levels of inflammatory biomarkers such as interleukin-6 (IL-6), 10 (IL-10), 1β (IL-1β), tumor necrosis factor-α (TNF-α) high-sensitivity C-reactive protein (hs-CRP) are associated with arterial stiffness in hypertension. Indeed, resistant hypertension (RHTN) leads to unfavorable prognosis attributed to poor blood pressure (BP) control and target organ damage. This study evaluated the potential impact of inflammatory biomarkers on arterial stiffness in RHTN. Methods. In this cross-sectional study, 32 RHTN, 20 mild hypertensive (HTN) and 20 normotensive (NT) patients were subjected to office BP and arterial stiffness measurements assessed by pulse wave velocity (PWV). Inflammatory biomarkers were measured in plasma samples. Results. PWV was increased in RHTN compared with HTN and NT (p < 0.05). TNF-α levels were significantly higher in RHTN and HTN than NT patients. No differences in IL-6 levels were observed. RHTN patients had a higher frequency of subjects with increased levels of IL-10 and IL-1β compared with HTN and NT patients. Finally, IL-1β was independently associated with PWV (p < 0.001; R2 = 0.5; β = 0.077). Conclusion. RHTN subjects have higher levels of inflammatory cytokines (TNF-α, IL-1β and IL-10) as well as increased arterial stiffness, and detectable IL-1β levels are associated arterial stiffness. These findings suggest that inflammation plays a possible role in the pathophysiology of RHTN.

Hypoadiponectinemia and aldosterone excess are associated with lack of blood pressure control in subjects with resistant hypertension

Obesity, arterial stiffness and high aldosterone levels can interact to cause resistant hypertension (RHTN). Lower adiponectin (APN) levels may be significantly associated with hypertension. However, the importance of hypoadiponectinemia as a complicating factor in the lack of blood pressure (BP) control in individuals with RHTN has not been demonstrated. Ninety-six RHTN patients were classified into uncontrolled (UCRHTN, n=44) and controlled (CRHTN, n=52) subgroups. Their APN and aldosterone levels, office and ambulatory BP (ABPM) measurements, endothelium-dependent brachial artery responses (flow-mediated dilation (FMD)), left ventricular mass index (LVMI) and pulse wave velocity (PWV) were evaluated. The UCRHTN subgroup had increased aldosterone levels, as well as higher LVMI and PWV. In addition, lower APN levels and impaired FMD response were found in this subgroup. The brachial and ABPM pulse pressures were inversely associated with the APN levels (r=−0.45, P=0.002; r=−0.33, P=0.03, respectively), as were the aldosterone levels and the PWV (r=−0.38, P=0.01; r=−0.36, P=0.02, respectively) in UCRHTN patients. The PWV was only significantly influenced by the APN level in the UCRHTN subgroup in the multivariate regression analysis. None of the correlations mentioned above were observed in the CRHTN subgroup. Hypoadiponectinemia and high aldosterone levels may therefore be implicated in resistance to antihypertensive therapy related to arterial stiffness.

An update on the pharmacogenetics of treating hypertension

Hypertension is a leading cause of cardiovascular mortality, but only one third of patients achieve blood pressure goals despite antihypertensive therapy. Genetic polymorphisms may partially account for the interindividual variability and abnormal response to antihypertensive drugs. Candidate gene and genome-wide approaches have identified common genetic variants associated with response to antihypertensive drugs. However, there is no currently available pharmacogenetic test to guide hypertension treatment in clinical practice. In this review, we aimed to summarize the recent findings on pharmacogenetics of the most commonly used antihypertensive drugs in clinical practice, including diuretics, angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers, beta-blockers and calcium channel blockers. Notably, only a small percentage of the genetic variability on response to antihypertensive drugs has been explained, and the vast majority of the genetic variants associated with antihypertensives efficacy and toxicity remains to be identified. Despite some genetic variants with evidence of association with the variable response related to these most commonly used antihypertensive drug classes, further replication is needed to confirm these associations in different populations. Further studies on epigenetics and regulatory pathways involved in the responsiveness to antihypertensive drugs might provide a deeper understanding of the physiology of hypertension, which may favor the identification of new targets for hypertension treatment and genetic predictors of antihypertensive response.

Plasma 8-isoprostane levels are associated with endothelial dysfunction in resistant hypertension.

BACKGROUND Impaired endothelial function and arterial stiffness are associated with hypertension and are important risk factors for cardiovascular events. Reactive oxygen species reduce nitric oxide bioavailability and have a pivotal role in endothelial function. Resistant hypertension (RHTN) is characterized by blood pressure (BP) above goal (140/90mmHg) in spite of the concurrent use of ≥3 antihypertensive drugs of different classes. This study evaluated the association between 8-isoprostane levels, an oxidative stress marker, endothelial function and arterial stiffness, in RHTN. METHODS Ninety-four RHTN and 55 well-controlled hypertensive (HT) patients were included. Plasma 8-isoprostane levels were determined by ELISA. Also, flow-mediated dilation (FMD) and pulse wave velocity (PWV) were evaluated to determine endothelial function and arterial stiffness, respectively. RESULTS Levels of 8-isoprostane were markedly higher in RHTN compared to HT patients (22.5±11.2 vs. 17.3±9.8pg/ml, p<0.05, respectively). A significant inverse correlation was observed between FMD and 8-isoprostane (r=-0.35, p=0.001) in RHTN. Finally, multiple logistic regression revealed that 8-isoprostane was a significant predictor of endothelial dysfunction (FMD≤median) in RHTN group. CONCLUSION RHTN showed markedly higher oxidative stress measured by 8-isoprostane, compared to HT patients. Taken together, our findings suggest the involvement of oxidative stress in endothelial function in RHTN.

Large-Scale Gene-Centric Analysis Identifies Polymorphisms for Resistant Hypertension

Background Resistant hypertension (RHTN), defined by lack of blood pressure (BP) control despite treatment with at least 3 antihypertensive drugs, increases cardiovascular risk compared with controlled hypertension. Yet, there are few data on genetic variants associated with RHTN. Methods and Results We used a gene‐centric array containing ≈50 000 single‐nucleotide polymorphisms (SNPs) to identify polymorphisms associated with RHTN in hypertensive participants with coronary artery disease (CAD) from INVEST‐GENES (the INnternational VErapamil‐SR Trandolapril STudy—GENEtic Substudy). RHTN was defined as BP≥140/90 on 3 drugs, or any BP on 4 or more drugs. Logistic regression analysis was performed in European Americans (n=904) and Hispanics (n=837), using an additive model adjusted for age, gender, randomized treatment assignment, body mass index, principal components for ancestry, and other significant predictors of RHTN. Replication of the top SNP was conducted in 241 European American women from WISE (Womens Ischemia Syndrome Evaluation), where RHTN was defined similarly. To investigate the functional effect of rs12817819, mRNA expression was measured in whole blood. We found ATP2B1 rs12817819 associated with RHTN in both INVEST European Americans (P‐value=2.44×10−3, odds ratio=1.57 [1.17 to 2.01]) and INVEST Hispanics (P=7.69×10−4, odds ratio=1.76 [1.27 to 2.44]). A consistent trend was observed at rs12817819 in WISE, and the INVEST‐WISE meta‐analysis result reached chip‐wide significance (P=1.60×10−6, odds ratio=1.65 [1.36 to 1.95]). Expression analyses revealed significant differences in ATP2B1 expression by rs12817819 genotype. Conclusions The ATP2B1 rs12817819 A allele is associated with increased risk for RHTN in hypertensive participants with documented CAD or suspected ischemic heart disease. Clinical Trial Registration URL: www.clinicaltrials.gov; Unique identifiers: NCT00133692 (INVEST), NCT00000554 (WISE).

Differential Gene Expression Profiles May Differentiate Responder and Nonresponder Patients with Rheumatoid Arthritis for Methotrexate (MTX) Monotherapy and MTX plus Tumor Necrosis Factor Inhibitor Combined Therapy

Objective. We aimed to evaluate whether the differential gene expression profiles of patients with rheumatoid arthritis (RA) could distinguish responders from nonresponders to methotrexate (MTX) and, in the case of MTX nonresponders, responsiveness to MTX plus anti-tumor necrosis factor-α (anti-TNF) combined therapy. Methods. We evaluated 25 patients with RA taking MTX 15–20 mg/week as a monotherapy (8 responders and 17 nonresponders). All MTX nonresponders received infliximab and were reassessed after 20 weeks to evaluate their anti-TNF responsiveness using the European League Against Rheumatism response criteria. A differential gene expression analysis from peripheral blood mononuclear cells was performed in terms of hierarchical gene clustering, and an evaluation of differentially expressed genes was performed using the significance analysis of microarrays program. Results. Hierarchical gene expression clustering discriminated MTX responders from nonresponders, and MTX plus anti-TNF responders from nonresponders. The evaluation of only highly modulated genes (fold change > 1.3 or < 0.7) yielded 5 induced (4 antiapoptotic and CCL4) and 4 repressed (4 proapoptotic) genes in MTX nonresponders compared to responders. In MTX plus anti-TNF non-responders, the CCL4, CD83, and BCL2A1 genes were induced in relation to responders. Conclusion. Study of the gene expression profiles of RA peripheral blood cells permitted differentiation of responders from nonresponders to MTX and anti-TNF. Several candidate genes in MTX non-responders (CCL4, HTRA2, PRKCD, BCL2A1, CAV1, TNIP1, CASP8AP2, MXD1, and BTG2) and 3 genes in MTX plus anti-TNF nonresponders (CCL4, CD83, and BCL2A1) were identified for further study.

Adipokines: Novel Players in Resistant Hypertension

Resistant hypertension (RH) is a multifactorial disease, frequently associated with obesity and characterized by blood pressure above goal (140/90 mm Hg) despite the concurrent use of ≥3 antihypertensive drugs of different classes. The mechanisms of obesity‐related hypertension include, among others, aldosterone excess and inflammatory adipokines, which have demonstrated a significant role in the pathogenesis of metabolic syndrome and RH. This review aims to summarize recent studies on the role of the adipokines leptin, resistin, and adiponectin in the pathophysiology of RH and target‐organ damage associated with this condition. The deregulation of adipokine levels has been associated with clinical characteristics frequently recognized in RH such as diabetes, hyperactivity of sympathetic and renin‐angiotensin‐aldosterone systems, and vascular and renal damage. Strategies to regulate adipokines may be promising for the management of RH and some clinical implications must be considered when managing controlled and uncontrolled patients with RH.

Effects of Angiotensin-Converting Enzyme Inhibition on Leptin and Adiponectin Levels in Essential Hypertension

Activation of the renin‐angiotensin‐aldosterone system (RAAS) and abnormal adipokine levels are biological alterations that affect blood pressure regulation and interact to link hypertension, obesity and metabolic diseases. While imbalanced levels of hormones produced by adipocytes including hypo‐adiponectinaemia and hyperleptinaemia were reported in hypertension, little is known about how antihypertensive therapy affects these alterations. This study aimed to evaluate the effects of enalapril on plasma adiponectin and leptin levels in hypertensive individuals. Thirty‐seven untreated hypertensive patients were prospectively treated with enalapril for 8 weeks. Blood samples were collected at baseline and after the treatment with enalapril. Plasma adiponectin and leptin levels were measured by enzyme‐linked immunoassay. We found significant increases in adiponectin levels after enalapril treatment (5.4 ± 3.7 versus 6.0 ± 4.5 μg/mL, mean±S.D., p = 0.04). Conversely, leptin levels were unchanged (18.0 ± 14.7 versus 18.4 ± 14.8 ng/mL, mean ± S.D., p = 0.31). Multiple linear regression revealed that baseline leptin is a significant predictor of systolic blood pressure reduction (β=0.269, p = 0.01) in hypertensive individuals treated with enalapril. While enalapril increases adiponectin levels in hypertensive individuals, baseline leptin levels predict blood pressure reduction in response to this therapy. These findings support the idea of an important relationship between RAAS and adipose tissue in hypertension and suggest that enalapril improves the adipokine profile, possibly allowing beneficial effects to overweight or obese hypertensive individuals.

Vascular Damage in Resistant Hypertension: TNF-Alpha InhibitionEffects on Endothelial Cells

Inflammatory cytokines have been associated with the pathophysiology of hypertension and target organ damage (TOD). Resistant hypertensive patients (RHTN) are characterized by poor blood pressure control and higher prevalence of TOD. This study evaluated the relationship between plasma levels of TNF-α and arterial stiffness (pulse wave velocity—PWV) in 32 RHTN and 19 normotensive subjects. Moreover, we investigated the effect of TNF-α inhibition on human endothelial cells (HUVECs) incubated with serum from RHTN and normotensive subjects. HUVECs containing serum obtained from normotensive (n = 8) and hypertensive (n = 8) individuals were treated with TNF-α inhibitor (infliximab). Cell suspensions were used for measurement of DNA fragmentation and reactive oxygen species (ROS) content. RHTN patients showed higher levels of TNF-α compared to normotensive subjects, as well as higher PWV. Positive correlation was found between TNF-α levels and PWV measures in the whole group. HUVECs incubated with serum from RHTN showed increased cell apoptosis and higher ROS content compared to normotensive subjects. Infliximab attenuated the apoptosis of HUVECs incubated with serum from RHTN, but no effect in ROS production was observed. Our findings suggest that TNF-α might mediate, at least in part, vascular damage in resistant hypertension.