High-circulating leptin levels are associated with increased blood pressure in uncontrolled resistant hypertension

Probiotics Bifidobacterium lactis M8 and Lactobacillus rhamnosus M9 prevent high blood pressure via modulating the gut microbiota composition and host metabolic products

IMPORTANCE

Elevated blood pressure affects 40% of the adult population, which accounts for high cardiovascular disease risk and further high mortality yearly. The global understanding of the gut microbiome for hypertension may provide important insights into the prevention. Bifidobacterium lactis M8 and Lactobacillus rhamnosus M9 originated from human breast milk, were able to decrease blood pressure, and modified metabolites in a high fructose-induced elevated blood pressure mouse model. Moreover, we found there was a close relationship between unexplored gut microbes and elevated blood pressure. Also, subsequently, the cross-link was explored among gut microbes, metabolites, and some metabolic pathways in gut microbial environment through introducing novel prediction methodology and bioinformatic analysis. It allowed us to hypothesize that probiotics can prevent elevated blood pressure via gut microbiota and related metabolism.Thus, utilization of dietary strategies (such as probiotics) to maintain the blood pressure level is of crucial importance.

A genome-wide association study identifies a novel candidate locus at the DLGAP1 gene with susceptibility to resistant hypertension in the Japanese population

Numerous genetic variants associated with hypertension and blood pressure are known, but there is a paucity of evidence from genetic studies of resistant hypertension, especially in Asian populations. To identify novel genetic loci associated with resistant hypertension in the Japanese population, we conducted a genome-wide association study with 2705 resistant hypertension cases and 21,296 mild hypertension controls, all from BioBank Japan. We identified one novel susceptibility candidate locus, rs1442386 on chromosome 18p11.3 (DLGAP1), achieving genome-wide significance (odds ratio (95% CI) = 0.85 (0.81–0.90), P = 3.75 × 10⁻⁸) and 18 loci showing suggestive association, including rs62525059 of 8q24.3 (CYP11B2) and rs3774427 of 3p21.1 (CACNA1D). We further detected biological processes associated with resistant hypertension, including chemical synaptic transmission, regulation of transmembrane transport, neuron development and neurological system processes, highlighting the importance of the nervous system. This study provides insights into the etiology of resistant hypertension in the Japanese population.

Mineralocorticoid receptors in the pathogenesis of insulin resistance and related disorders: from basic studies to clinical disease

Aldosterone is a steroid hormone that regulates blood pressure and cardiovascular function by acting on renal and vascular mineralocorticoid receptors (MRs) to promote sodium retention and modulate endothelial function. Indeed, MRs are expressed in endothelial cells, vascular smooth muscle cells, adipocytes, immune cells, skeletal muscle cells, and cardiomyocytes. Excessive aldosterone and associated MR activation impair insulin secretion, insulin metabolic signaling to promote development of diabetes, and the related cardiometabolic syndrome. These adverse effects of aldosterone are mediated, in part, via increased inflammation, oxidative stress, dyslipidemia, and ectopic fat deposition. Therefore, inhibition of MR activation may have a beneficial effect in prevention of impaired insulin metabolic signaling, type 2 diabetes, and cardiometabolic disorders. This review highlights findings from the recent surge in research regarding MR-related cardiometabolic disorders as well as our contemporary understanding of the detrimental effects of excess MR activation on insulin metabolic signaling.

Advances in Cardiovascular Biomarker Discovery

Cardiovascular diseases are the leading causes of mortality worldwide. Among them, hypertension and its pathological complications pose a major risk for the development of other cardiovascular diseases, including heart failure and stroke. Identifying novel and early stage biomarkers of hypertension and other cardiovascular diseases is of paramount importance in predicting and preventing the major morbidity and mortality associated with these diseases. Biomarkers of such diseases or predisposition to their development are identified by changes in a specific indicator’s expression between healthy individuals and patients. These include changes in protein and microRNA (miRNA) levels. Protein profiling using mass spectrometry and miRNA screening utilizing microarray and sequencing have facilitated the discovery of proteins and miRNA as biomarker candidates. In this review, we summarized some of the different, promising early stage protein and miRNA biomarker candidates as well as the currently used biomarkers for hypertension and other cardiovascular diseases. Although a number of promising markers have been identified, it is unlikely that a single biomarker will unambiguously aid in the classification of these diseases. A multi-marker panel-strategy appears useful and promising for classifying and refining risk stratification among patients with cardiovascular disease.

Molecular Mechanisms of Adiponectin-Induced Attenuation of Mechanical Stretch-Mediated Vascular Remodeling

Hypertension induces vascular hypertrophy, which changes blood vessels structurally and functionally, leading to reduced tissue perfusion and further hypertension. It is also associated with dysregulated levels of the circulating adipokines leptin and adiponectin (APN). Leptin is an obesity-associated hormone that promotes vascular smooth muscle cell (VSMC) hypertrophy. APN is a cardioprotective hormone that has been shown to attenuate hypertrophic cardiomyopathy. In this study, we investigated the molecular mechanisms of hypertension-induced VSMC remodeling and the involvement of leptin and APN in this process. To mimic hypertension, the rat portal vein (RPV) was mechanically stretched, and the protective effects of APN on mechanical stretch-induced vascular remodeling and the molecular mechanisms involved were examined by using 10 μg/ml APN. Mechanically stretching the RPV significantly decreased APN protein expression after 24 hours and APN mRNA expression in a time-dependent manner in VSMCs. The mRNA expression of the APN receptors AdipoR1, AdipoR2, and T-cadherin significantly increased after 15 hours of stretch. The ratio of APN/leptin expression in VSMCs significantly decreased after 24 hours of mechanical stretch. Stretching the RPV for 3 days increased the weight and [³H]-leucine incorporation significantly, whereas APN significantly reduced hypertrophy in mechanically stretched vessels. Stretching the RPV for 10 minutes significantly decreased phosphorylation of LKB1, AMPK, and eNOS, while APN significantly increased p-LKB1, p-AMPK, and p-eNOS in stretched vessels. Mechanical stretch significantly increased p-ERK1/2 after 10 minutes, whereas APN significantly reduced stretch-induced ERK1/2 phosphorylation. Stretching the RPV also significantly increased ROS generation after 1 hour, whereas APN significantly decreased mechanical stretch-induced ROS production. Exogenous leptin (3.1 nM) markedly increased GATA-4 nuclear translocation in VSMCs, whereas APN significantly attenuated leptin-induced GATA-4 nuclear translocation. Our results decipher molecular mechanisms of APN-induced attenuation of mechanical stretch-mediated vascular hypertrophy, with the promising potential of ultimately translating this protective hormone into the clinic.

The Role of Adipokines in the Development of Arterial Stiffness and Hypertension

The study aimed to assess the role and the relationship of adipokines as well as parameters of arterial stiffness in newly diagnosed hypertension. Forty-nine newly diagnosed hypertensive cases (median age 47 ± 6 years) and 48 normotensive patients (median age 47 ± 6 years) were enrolled to this study. Patients underwent echocardiography, noninvasive assessment of hemodynamic parameters using SphygmoCor tonometer (Atcor Med). The levels of the adipokines-leptin, adiponectin, and resistin-were investigated. The augmentation pressure, augmentation index, and pulse wave velocity (PWV) were higher in patients with hypertension compared with controls (Ps < .05). Patients with hypertension had higher E/E' ratio, higher diameter of left atrium, and lower tricuspid annular plane systolic excursion compared with the control group (Ps < .05). Patients with hypertension had significant higher levels of leptin (ng/mL) and lower levels of adiponectin (μg/mL) compared with normotensive patients. The multivariate analysis showed that PWV (odds ratio [OR] 1.95, 95% CI, 1.2-2.9; P = .002) and leptin level (OR 1.01, 95% CI, 1.004-1.031; P = .01) were significantly associated with hypertension. Arterial stiffness as determined by PWV and leptin are associated with newly diagnosed hypertension. Elevated serum leptin level may influence the potential mechanism leading to sympathetic activation.

Pro-inflammatory Cytokines and Resistant Hypertension: Potential for Novel Treatments?

PURPOSE OF REVIEW

To gather data from studies evaluating the pro-inflammatory profile of individuals with resistant hypertension (RH), and bring a clinical update of new and potential complementary therapies to treat inflammation in RH.

RECENT FINDINGS

Increases in pro-inflammatory cytokines are related to elevated blood pressure and target organ damage in RH patients. Clinical and experimental studies have shown that some biological therapies, especially TNF-α inhibitors, regulated pro- and anti-inflammatory cytokines associated with improvements in clinical outcomes, although they are not yet reported in RH. New emerging therapies to treat inflammation in RH, although promising, are still hypotheses that have not been scientifically confirmed in clinical trials. For this reason, inflammation-target treatments, such as the TNF-α and IL-6 inhibitors, should be encouraged for testing as complementary therapies in RH in order to elucidate their potential benefits.

A Proposed Inflammatory Score of Circulating Cytokines/Adipokines Associated with Resistant Hypertension, but Dependent on Obesity Parameters

Background

There is evidence that subclinical systemic inflammation is present in resistant hypertension (RHTN).

Objective

The aim of the study was to develop an integrated measure of circulating cytokines/adipokines involved in the pathophysiology of RHTN.

Methods

RHTN (n = 112) and mild to moderate hypertensive (HTN) subjects (n=112) were studied in a cross-sectional design. Plasma cytokines/adipokines (TNF-alpha, interleukins [IL]-6, -8, -10, leptin and adiponectin) values were divided into tertiles, to which a score ranging from 1 (lowest tertile) to 3 (highest tertile) was assigned. The inflammatory score (IS) of each subject was the sum of each pro-inflammatory cytokine scores from which anti-inflammatory cytokines (adiponectin and IL-10) scores were subtracted. The level of significance accepted was alpha = 0.05.

Results

IS was higher in RHTN subjects compared with HTN subjects [4 (2-6) vs. 3 (2-5); p = 0.02, respectively]. IS positively correlated with body fat parameters, such as body mass index (r = 0.40; p < 0.001), waist circumference (r = 0.30; p < 0.001) and fat mass assessed by bioelectrical impedance analysis (r = 0.31; p < 0.001) in all hypertensive subjects. Logistic regression analyses revealed that IS was an independent predictor of RHTN (OR = 1.20; p = 0.02), independent of age, gender and race, although it did not remain significant after adjustment for body fat parameters.

Conclusion

A state of subclinical inflammation defined by an IS including TNF-alpha, IL-6, IL-8, IL-10, leptin and adiponectin is associated with obese RHTN. In addition, this score correlates with obesity parameters, independently of hypertensive status. The IS may be used for the evaluation of conditions involving low-grade inflammation, such as obesity-related RHTN. Indeed, it also highlights the strong relationship between obesity and inflammatory process.

Plasma leptin level is positively associated with blood pressure measures independent of gender and BMI

Background: Since the introduction of leptin, many studies suggest an important role for this hormone in obesity-related hypertension. However, in non-obese patients, there are controversial results regarding the possible role of leptin in essential hypertension especially in both sexes and different groups of body mass index (BMI). We aimed to evaluate the association of leptin and hypertension in both female and male gender.Materials and Methods: This cross-sectional study was conducted, recruiting 80 essential hypertensive patients and 80 healthy normotensive volunteers using convenience sampling method. Subjects without history of diabetes mellitus, hyperlipidemia, smoking, thyroid disease and insulin or corticosteroid use were included in two groups of normotensive and hypertensive subjects who were matched for age, sex and BMI. Systolic and diastolic blood pressure (SBP and DBP), weight and height were measured for all subjects and a blood sample was obtained for measurement of leptin, fasting blood sugar and lipid profiles.Results: Leptin was significantly higher in hypertensive patients as compared to normotensive subjects in all study population and both male and female subgroups (p < 0.001). Statistically significant correlation was also found between leptin and both SBP and DBP in above-mentioned subgroups. In comparison of controlled and uncontrolled hypertensive patients, leptin was significantly higher in uncontrolled hypertensive patients (p < 0.001).Conclusion: Comparing two groups of hypertensive and normotensive subjects, leptin is found to be positively correlated with hypertension in both genders. Leptin level also tends to be higher in uncontrolled hypertensive patients which may indicate a possible role for leptin in mechanism of uncontrolled hypertension.

Plasma Leptin Concentration and Sympathetic Nervous Activity in Older Adults With Physical Dysfunction

Context

Previous research has shown a positive relationship between plasma leptin and sympathetic nervous activity. High plasma leptin activate inflammatory cytokines and lead to muscle wasting. However, studies have detected low sympathetic nervous activity and high plasma leptin in older adults with muscle wasting, sarcopenia, and frailty. High plasma leptin do not seem to correlate with high sympathetic nervous activity. However, their relationship in older adults remains unclear.

Objective

We investigated the relationship between plasma leptin and sympathetic nervous activity in older adults.

Design, Setting, and Participants

We conducted a cross-sectional study and analyzed the results from 69 participants aged ≥75 years. Sympathetic nervous activity was measured by heart rate variability, obtained from 24-hour Holter monitoring. A functional independence measure (FIM) and Barthel index were used to assess physical function.

Results

The plasma leptin was higher in women (men, 3.4 ± 2.8 ng/mL; women, 6.6 ± 6.5 ng/mL; P = 0.024). Plasma leptin was negatively and substantially related to the FIM (β = −0.233; P = 0.049) and Barthel index (β = −0.298, P = 0.018) after adjustment for covariates. However, the data showed no relationship between the plasma leptin and sympathetic nervous activity.

Conclusions

We could not detect an association between sympathetic nervous activity and plasma leptin in older adults. This might suggest a failure of the feedback system of the sympathetic nervous system, leading to muscle wasting in older adults.

Continuous Positive Airway Pressure Reduces Night-Time Blood Pressure and Heart Rate in Patients With Obstructive Sleep Apnea and Resistant Hypertension: The RHOOSAS Randomized Controlled Trial

Objective

Most patients with resistant hypertension (RH) have obstructive sleep apnea (OSA). We aimed to determine the impact of OSA and continuous positive airway pressure (CPAP) treatment on the leptin profile and blood pressure (BP) in patients with RH.

Methods

After an initial case-control study (RH with and without OSA), we performed a randomized, single blind study in OSA + RH patients receiving either sham CPAP (3 months) followed by active CPAP (6 months) or 6 months of active CPAP. The primary outcome was the comparison of leptin levels between groups of RH patients with or without OSA. Secondary outcomes were the comparison of metabolic parameters, biomarkers of sympathetic activity, and BP indices between the two groups of RH patients with or without OSA. The same outcomes were then evaluated and compared before and after sham and effective CPAP intervention.

Results

Sixty-two patients (60 ± 10 years; 77% men) with RH (24-h daytime systolic BP (SBP)/diastolic BP: 145 ± 13/85 ± 10 mmHg, 3.7 antihypertensive drugs) were included. The 37 RH patients exhibiting OSA (60%) were predominantly men (87 vs 64% for non-OSA patients), with a greater prevalence of metabolic syndrome and higher creatininemia. Their leptin concentrations were significantly lower than in non-OSA patients [9 (6; 15) vs 17 (6; 29) ng/mL] but increased after 6 months of CPAP. Three months of effective CPAP significantly decreased night-time SBP by 6.4 mmHg and heart rate (HR) by 6.0 bpm, compared to sham CPAP.

Conclusion

The association between OSA and RH corresponds to a specific, predominately male phenotype with a higher burden of metabolic syndrome and higher creatininemia but there was no significant difference between OSA and non-OSA patients regarding BP indices, and the number of antihypertensive drugs used. Active CPAP could be efficient at decreasing night-time BP and HR, but there was no difference between CPAP and sham CPAP groups for all metabolic and SNS markers (NCT00746902 RHOOSAS).

Associations of the hypertension-related single nucleotide polymorphism rs11191548 with high-density lipoprotein cholesterol and leptin in Chinese children

Background

The genome-wide association study has founded hypertension-related single nucleotide polymorphism (SNP) rs11191548 near CYP17A1 encoding a key enzyme involved in steroid metabolism, but the molecular mechanisms are not understood and the associations of the SNP with hypertension-related traits are not fully described, especially in children. The aim of the present study is to investigate the associations between the SNP and two hypertension-related traits, lipids and leptin.

Methods

We genotyped the SNP in Beijing Child and Adolescent Metabolic Syndrome (BCAMS) study. A total of 3503 children participated in the study.

Results

The SNP rs11191548 was significantly associated with high-density lipoprotein cholesterol (HDL) (P = 0.014 and 0.028, respectively) and leptin (P = 0.011 and 0.026, respectively) under an additive model after adjustment for age, gender, and systolic blood pressure (SBP) or diastolic blood pressure (DBP). There was a statistically significant association of rs11191548 with high leptin after adjustment for age, gender, and SBP or DBP. The P-values remain significant after correction for multiple testing.

Conclusions

We demonstrate for the first time that the SNP rs11191548 near CYP17A1 is associated with HDL and leptin in Chinese children. These novel findings provide important evidence that HDL and leptin maybe possibly mediate the process of CYP17A1 involved in hypertension.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0523-y) contains supplementary material, which is available to authorized users.

Decoding resistant hypertension signalling pathways

Resistant hypertension (RH) is a clinical condition in which the hypertensive patient has become resistant to drug therapy and is often associated with increased cardiovascular morbidity and mortality. Several signalling pathways have been studied and related to the development and progression of RH: modulation of sympathetic activity by leptin and aldosterone, primary aldosteronism, arterial stiffness, endothelial dysfunction and variations in the renin-angiotensin-aldosterone system (RAAS). miRNAs comprise a family of small non-coding RNAs that participate in the regulation of gene expression at post-transcriptional level. miRNAs are involved in the development of both cardiovascular damage and hypertension. Little is known of the molecular mechanisms that lead to development and progression of this condition. This review aims to cover the potential roles of miRNAs in the mechanisms associated with the development and consequences of RH, and explore the current state of the art of diagnostic and therapeutic tools based on miRNA approaches.

Effects of leptin and leptin receptor SNPs on clinical- and metabolic-related traits in apparent treatment-resistant hypertension

Leptin is associated to the lack of blood pressure control as well as target organ damage in resistant hypertensive (RH) subjects. Single-nucleotide polymorphisms (SNPs) rs7799039 and rs1137101 in leptin (LEP) and leptin receptor (LEPR) genes, respectively, are associated with cardiovascular disease and metabolic syndrome. We evaluated the association of these two SNPs with clinical and biochemical features in 109 apparent treatment-RH subjects (aTRH) and 125 controlled hypertensives. Homozygous genotypes GG (n = 43) vs. AA (n = 14) for rs7799039 and AA (n = 34) vs. GG (n = 26) genotypes for rs1137101 were compared in aTRH subjects. There was no difference in leptin levels among both SNPs. On the other hand, LEP SNP (GG vs. AA) associated with the levels of glycated haemoglobin (6.4 ± 1.4 vs. 7.8 ± 2.3%, p = 0.03), insulin (8.6 ± 4.6 vs. 30.6 ± 27.7 uUI/mL, p = 0.01), HDL-cholesterol (51 ± 16 vs. 39 ± 11 mg/dL, p = 0.001) and PWV (9.5 ± 2.1 vs. 11.2 ± 2.8 m/s, p = 0.03). LEPR SNP (AA vs. GG), associated with heart rate (69 ± 12 vs. 67 ± 12 bpm, p = 0.03), fat mass (31 ± 11 vs. 24 ± 8 kg, p = 0.03) and triglycerides levels (175 ± 69 vs. 135 ± 75 mg/dL, p = 0.03). These findings may be clinically useful for identifying a group of aTRH who may have a LEP and/or LEPR gene variants, which may predispose this specific group to worse or better outcomes.

An update on the role of adipokines in arterial stiffness and hypertension

Adipokines are hormones produced by adipocytes and have been involved in multiple pathologic pathways, including inflammatory and cardiovascular complications in essential hypertension. Arterial stiffness is a frequent vascular complication that represents increased cardiovascular risk in hypertensive patients. Adipokines, such as adiponectin, leptin and resistin, might be implicated in hypertension, as well as in vascular alterations associated with this condition. Arterial stiffness has proven to be a predictor of cardiovascular events. Obesity and target-organ damage such as arterial stiffness are features associated with hypertension. This review aims to update the association between adipokines and arterial stiffness in essential and resistant hypertension (RHTN).

Adipocyte-Derived Hormone Leptin Is a Direct Regulator of Aldosterone Secretion, Which Promotes Endothelial Dysfunction and Cardiac Fibrosis

BACKGROUND

In obesity, the excessive synthesis of aldosterone contributes to the development and progression of metabolic and cardiovascular dysfunctions. Obesity-induced hyperaldosteronism is independent of the known regulators of aldosterone secretion, but reliant on unidentified adipocyte-derived factors. We hypothesized that the adipokine leptin is a direct regulator of aldosterone synthase (CYP11B2) expression and aldosterone release and promotes cardiovascular dysfunction via aldosterone-dependent mechanisms.

METHODS AND RESULTS

Immunostaining of human adrenal cross-sections and adrenocortical cells revealed that adrenocortical cells coexpress CYP11B2 and leptin receptors. Measurements of adrenal CYP11B2 expression and plasma aldosterone levels showed that increases in endogenous (obesity) or exogenous (infusion) leptin dose-dependently raised CYP11B2 expression and aldosterone without elevating plasma angiotensin II, potassium or corticosterone. Neither angiotensin II receptors blockade nor α and β adrenergic receptors inhibition blunted leptin-induced aldosterone secretion. Identical results were obtained in cultured adrenocortical cells. Enhanced leptin signaling elevated CYP11B2 expression and plasma aldosterone, whereas deficiency in leptin or leptin receptors blunted obesity-induced increases in CYP11B2 and aldosterone, ruling out a role for obesity per se. Leptin increased intracellular calcium, elevated calmodulin and calmodulin-kinase II expression, whereas calcium chelation blunted leptin-mediated increases in CYP11B2, in adrenocortical cells. Mineralocorticoid receptor blockade blunted leptin-induced endothelial dysfunction and increases in cardiac fibrotic markers.

CONCLUSIONS

Leptin is a newly described regulator of aldosterone synthesis that acts directly on adrenal glomerulosa cells to increase CYP11B2 expression and enhance aldosterone production via calcium-dependent mechanisms. Furthermore, leptin-mediated aldosterone secretion contributes to cardiovascular disease by promoting endothelial dysfunction and the expression of profibrotic markers in the heart.

Drug therapy of apparent treatment-resistant hypertension: focus on mineralocorticoid receptor antagonists

Apparent treatment-resistant hypertension (aTRH) is defined as blood pressure (BP) >140/90 mmHg despite three different antihypertensive drugs including a diuretic. aTRH is associated with an increased risk of cardiovascular events, including stroke, chronic renal failure, myocardial infarction, congestive heart failure, aortic aneurysm, atrial fibrillation, and sudden death. Preliminary studies of renal nerve ablation as a therapy to control aTRH were encouraging. However, these results were not confirmed by the Symplicity 3 trial. Therefore, attention has refocused on drug therapy. Secondary forms of hypertension and associated conditions such as obesity, sleep apnea, and primary aldosteronism are common in patients with aTRH. The pivotal role of aldosterone in the pathogenesis of aTRH in many cases is well recognized. For patients with aTRH, the Joint National Committee-8, the European Society of Hypertension, and a recent consensus conference recommend that a diuretic, ACE inhibitor, or angiotensin receptor blocker and calcium channel blocker combination be used to maximally tolerated doses before starting a 'fourth-line' drug such as a mineralocorticoid receptor (MR) antagonist. Although the best fourth-line drug for aTRH has not been extensively investigated, a number of studies summarized here show that an MR antagonist is effective in reducing BP when added to the standard multi-drug regimen.

Role of MMP-2 and MMP-9 in resistance to drug therapy in patients with resistant hypertension

Background

Despite the increased evidence of the important role of matrix metalloproteinases (MMP-9 and MMP‑2) in the pathophysiology of hypertension, the profile of these molecules in resistant hypertension (RHTN) remains unknown.

Objectives

To compare the plasma levels of MMP-9 and MMP-2 and of their tissue inhibitors (TIMP-1 and TIMP-2, respectively), as well as their MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios, between patients with controlled RHTN (CRHTN, n=41) and uncontrolled RHTN (UCRHTN, n=35). In addition, the association of those parameters with clinical characteristics, office blood pressure (BP) and arterial stiffness (determined by pulse wave velocity) was evaluate in those subgroups.

Methods

This study included 76 individuals diagnosed with RHTN and submitted to physical examination, electrocardiogram, and laboratory tests to assess biochemical parameters.

Results

Similar values of MMP-9, MMP-2, TIMP-1, TIMP-2, and MMP-9/TIMP-1 and MMP-2/TIMP-2 ratios were found in the UCRHTN and CRHTN subgroups (P>0.05). A significant correlation was found between diastolic BP (DBP) and MMP-9/TIMP-1 ratio (r=0.37; P=0.02) and DPB and MMP-2 (r=-0.40; P=0.02) in the UCRHTN subgroup. On the other hand, no correlation was observed in the CRHTN subgroup. Logistic regression models demonstrated that MMP-9, MMP-2, TIMP-1, TIMP-2 and their ratios were not associated with the lack of BP control.

Conclusion

These findings suggest that neither MMP-2 nor MMP-9 affect BP control in RHTN subjects.

The Intricate Network of Adipokines and Stroke

Cerebrovascular disorders, particularly ischemic stroke, are one of the most common neurological disorders. High rates of overweight and obesity support an interest in the role of adipose tissue and adipose tissue releasing cytokines in inducing associated comorbidities. Adipokines can serve as a key messenger to central energy homeostasis and metabolic homeostasis. They can contribute to the crosstalk between adipose tissue and brain. However recent research has offered ambiguous data on the network of adipose tissue, adipokines, and vascular disorders. In our paper we provide a critical insight into the role of adipokines in evolution of ischemic stroke.

Adiponectin -11377C/G and +276G/T polymorphisms affect adiponectin levels but do not modify responsiveness to therapy in resistant hypertension

Resistant hypertension (RHTN) is a multifactorial and polygenic disease, frequently associated with obesity. Low plasma adiponectin levels, a hormone produced by the adipose tissue, were associated with RHTN. Single nucleotide polymorphisms (SNPs) -11377C/G (rs266729) and +276G/T (rs1501299) in ADIPOQ (adiponectin gene) were associated with hypertension. This study evaluated the association between two SNPs (-11377C/G and +276G/T) and adiponectin levels in RHTN. This study comprised 109 patients with RHTN genotyped for both polymorphisms. A cross-sectional study was designed to compare features of CC homozygous versus G allele carriers for -11377C/G and GG homozygous versus T allele carriers for +276G/T. Office and ambulatory BP measurements were similar among genotypes subgroups in both SNPs as well as the markers of target organ damage (arterial stiffness, left ventricular mass index and microalbuminuria). Adiponectin concentrations were significantly higher in CC compared to G carrier for -11377C/G (CC:7.0 (4.0-10.2) versus G allele:5.5 (2.5-7.9), p = 0.04) and lower in GG compared to T carrier for +276G/T (GG:5.3 (2.3-7.7) versus T allele:7.1 (3.6-10.5), p = 0.04). Adjusting for systolic ambulatory BP, body mass index, age, gender, race and presence of type 2 diabetes, multiple linear regression analyses revealed that the minor alleles G (β-coefficient= -0.14, SE=0.07, p = 0.03) and T (β-coefficient=0.12, SE=0.06, p = 0.04) were independent predictors of adiponectin. The -11377C/G and +276G/T SNPs in ADIPOQ were associated with adiponectin levels in RHTN individuals.

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.

Resistant hypertension in diabetes mellitus

Resistant hypertension in diabetes is associated with poor cardiovascular and renal outcomes. This brief review will examine the definitions and epidemiology of resistant hypertension and consider the differences between apparent resistant hypertension and truly resistant or refractory hypertension. It will review the role of the sympathetic nervous system in resistant hypertension. It will consider the relationship between obesity and leptin resistance and sympathetic signaling; the role of obstructive sleep apnea in resistant hypertension; and the role of aldosterone in resistant hypertension. It will conclude by mentioning briefly renal nerve ablation.

Modulation of aldosterone levels by -344 C/T CYP11B2 polymorphism and spironolactone use in resistant hypertension

Interindividual variability in plasma aldosterone levels comprises environmental and genetic sources. Increased aldosterone levels have been associated with higher risk of hypertension and target-organ damage related to hypertension. Aldosterone excess and intravascular volume expansion are implicated in pathophysiology of resistant hypertension (RH). We sought to investigate whether -344 C/T polymorphism (rs1799998) in aldosterone synthase gene (CYP11B2) is associated with plasma aldosterone levels in patients with resistant hypertension. Sixty-two patients with resistant hypertension were enrolled in this cross-sectional study. Genotypes were obtained by allelic discrimination assay using real time polymerase chain reaction. Multivariable linear regression was used to identify whether TT genotype was a predictor of aldosterone levels. No differences in clinical and laboratorial parameters were found among genotype groups. We found an additive effect of the T allele on plasma aldosterone concentration in RH. Also, there was higher aldosterone levels in TT homozygous under use of spironolactone compared with C carriers and compared with TT subjects who was not under use of spironolactone. TT genotype and the use of spironolactone were significant predictors of aldosterone levels in RH subjects. Plasma aldosterone concentration is significantly associated with -344 C/T CYP11B2 polymorphism and with the treatment with spironolactone in resistant hypertensive subjects.

Deregulation of adipokines related to target organ damage on resistant hypertension

Resistant hypertension (RHTN) includes patients with controlled blood pressure (BP) (CRHTN) and uncontrolled BP (UCRHTN). In fact, RHTN patients are more likely to have target organ damage (TOD), and resistin, leptin and adiponectin may affect BP control in these subjects. We assessed the relationship between adipokines levels and arterial stiffness, left ventricular hypertrophy (LVH) and microalbuminuria (MA). This cross-sectional study included CRHTN (n=51) and UCRHTN (n=38) patients for evaluating body mass index, ambulatory blood pressure monitoring, plasma adiponectin, leptin and resistin concentrations, pulse wave velocity (PWV), MA and echocardiography. Leptin and resistin levels were higher in UCRHTN, whereas adiponectin levels were lower in this same subgroup. Similarly, arterial stiffness, LVH and MA were higher in UCRHTN subgroup. Adiponectin levels negatively correlated with PWV (r=-0.42, P<0.01), and MA (r=-0.48, P<0.01) only in UCRHTN. Leptin was positively correlated with PWV (r=0.37, P=0.02) in UCRHTN subgroup, whereas resistin was not correlated with TOD in both subgroups. Adiponectin is associated with arterial stiffness and renal injury in UCRHTN patients, whereas leptin is associated with arterial stiffness in the same subgroup. Taken together, our results showed that those adipokines may contribute to vascular and renal damage in UCRHTN patients.

Leptin-induced endothelial dysfunction is mediated by sympathetic nervous system activity

BACKGROUND

The adipocyte-derived hormone leptin is elevated in obesity and may contribute to vascular risk associated with obesity. The mechanism(s) by which leptin affects vascular disease is unclear, although leptin has been shown to increase sympathetic activity. The aim of this study was to investigate the effect of leptin treatment on endothelial function and the role of the local sympathetic nervous system in mediating these effects.

METHODS AND RESULTS

Recombinant leptin was administered to C57BL6/J mice every other day for 1 week. Mesenteric arteriole myography revealed that leptin treatment caused significant impairment of endothelium-dependent vasorelaxation. Although leptin alone did not raise aortic blood pressure, leptin treatment augmented the blood pressure response to angiotensin II. The effects of leptin on mesenteric arteriolar function and aortic blood pressure response to angiotensin II were neutralized following sympathetic denervation to the mesenteric vasculature. The superoxide scavenger TEMPOL was also effective in preventing the effects of leptin on endothelial dysfunction.

CONCLUSIONS

Leptin causes endothelial dysfunction and enhances the effects of angiotensin II on blood pressure. These effects of leptin are mediated by sympathetic nervous system activation and superoxide and may contribute to vascular stiffness and hypertension in obesity.