Multimarker approach to evaluate the incidence of the metabolic syndrome and longitudinal changes in metabolic risk factors: the Framingham Offspring Study

The dynamic behaviour of metabolic syndrome and its components in an eight-year population-based cohort from the Mediterranean

Background

The significant rise in the prevalence of obesity coincides with the considerable increase in the prevalence of metabolic syndrome (MS) currently being observed worldwide. The components of MS are not static and their dynamics, such as the order of their occurrence, or the time of exposure to them are, as yet, unknown but could well be clinically relevant. Our objective was to study the dynamic behaviour of MS and its components in a large population-based cohort from a Mediterranean region.

Methods and findings

Our study employed a retrospective cohort (between January 1, 2005 and December 31, 2012) made up of individuals from the general population in a region in the northeast of Catalonia, Spain. Given that most of the explicative variables of the risk of having MS were time dependent and, therefore, the risk was not proportional, we used the Andersen-Gill (AG) model to perform a multivariate survival analysis and inferences were performed using a Bayesian framework.

Thirty-nine percent of the participants developed MS; 44.6% of them with a single limited episode. Triglycerides and low HDL cholesterol, together with obesity, are components associated with the first occurrence of MS. Components related to the metabolism of glucose are associated with a medium risk of having a first episode of MS, and those related to blood pressure are associated with a lower risk. When the components related to blood pressure and the metabolism of glucose appear first, they determine the appearance of the first episode of MS. The variables concerning the persistence of MS are those that correspond to clinical conditions that do not have well-established drug treatment criteria.

Conclusions

Our results suggest that the components related to the metabolism of glucose and to high blood pressure appear early on and act as biomarkers for predicting MS, while the components related to obesity and dyslipidaemia, although essential for the development of MS, appear later. Making lifestyle changes reduces the conditions associated with the persistence of MS.

Effect of eplerenone in patients with heart failure and reduced ejection fraction: potential effect modification by abdominal obesity. Insight from the EMPHASIS-HF trial

AIMS

An excessive production of aldosterone influences outcome in patients with heart failure (HF) and in obese patients. Findings from laboratory studies suggest that chronic aldosterone blockade maybe more beneficial in abdominally obese HF-prone rats. In the current study, we investigated if the clinical response to a mineralocorticoid receptor antagonist in mildly symptomatic HF patients varied by abdominal obesity.

METHODS AND RESULTS

A total of 2587 NYHA class II, reduced ejection fraction HF (HFrEF) patients enrolled in the EMPHASIS-HF trial were randomly assigned to eplerenone and placebo. In this post hoc analysis, patients were categorized according to waist circumference (WC) (normal if WC < 102 cm in men and < 88 cm in women; abdominal obesity if WC ≥ 102 cm in men and ≥ 88 cm women). The potential statistical interaction between the treatment and WC was assessed on the primary endpoint of death from cardiovascular causes or hospitalization for HF and other secondary endpoints. Over a median follow-up of 21 months, a significant benefit of eplerenone for the primary outcome was noted in both normal [hazard ratio (HR) 0.77, 95% confidence interval (CI) 0.61-0.98, P = 0.03] and increased (HR 0.48, 95% CI 0.37-0.63, P < 0.0001) WC subgroups, but the latter patients appeared to receive greater benefit than patients with normal WC (P for interaction = 0.01). This suggests a significant quantitative (treatment effect varies in magnitude by subgroup, but is always in same direction) rather than a qualitative interaction (direction of the treatment effect varies by subgroup) between eplerenone and WC in the adjusted analysis. Mean doses of eplerenone, blood pressure and serum potassium changes and adverse events were similar between WC subgroups.

CONCLUSION

In EMPHASIS-HF, eplerenone improved outcomes in HFrEF patients with and without abdominal obesity, although the benefit appeared to be more pronounced among those with abdominal obesity. The findings are potentially hypothesis generating and need to be replicated in other HFrEF populations.

A mini-network balance model for evaluating the progression of cardiovascular complications in Goto-Kakizaki rats

Cardiovascular complications represent a leading cause of mortality in patients with type 2 diabetes mellitus (T2DM). During such complicated progression, subtle variations in the cardiovascular risk (CVR)-related biomarkers have been used to identify cardiovascular disease at the incipient stage. In this study we attempt to integrally characterize the progression of cardiovascular complications and to assess the beneficial effects of metformin combined with salvianolic acid A (Sal A), in Goto-Kakizaki (GK) rats with spontaneous T2DM. The rats were treated with metformin (200 mg·kg^-1·d^-1, ig) alone or in combination with Sal A (1 mg·kg^-1·d^-1, ip) at ages from 8 to 22 weeks. During the treatment, the levels of asymmetric dimethylarginine, L-arginine, superoxide dismutase, malondialdehyde, glucose, high density lipoprotein and low density lipoprotein were assessed. Based on alterations in these biomarkers, a mini-network balance model was established using matrixes and vectors. Radar charts were created to visually depict the disruption of CVR-related modules (endothelial function, oxidative stress, glycation and lipid profiles). The description for the progression of cardiovascular disorder was quantitatively represented by u, the dynamic parameter of the model. The modeling results suggested that untreated GK rats tended to have more severe cardiovascular complications than the treatment groups. Metformin monotherapy retarded disease deterioration, whereas the combination treatment ameliorated the disease progression via restoring the balance. The current study, which focused on the balance of the mini-network and interactions among CVR-related modules, proposes a novel method for evaluating the progression of cardiovascular complications in T2DM as well as a more beneficial intervention strategy.

Serum potassium is a predictor of incident diabetes in African Americans with normal aldosterone: the Jackson Heart Study

BACKGROUND

Low-normal potassium is a risk factor for diabetes and may account for some of the racial disparity in diabetes risk. Aldosterone affects serum potassium and is associated with insulin resistance.

OBJECTIVES

We sought to confirm the association between potassium and incident diabetes in an African-American cohort, and to determine the effect of aldosterone on this association.

DESIGN

We studied participants from the Jackson Heart Study, an African-American adult cohort, who were without diabetes at baseline. With the use of logistic regression, we characterized the associations of serum, dietary, and urinary potassium with incident diabetes. In addition, we evaluated aldosterone as a potential effect modifier of these associations.

RESULTS

Of 2157 participants, 398 developed diabetes over 8 y. In a minimally adjusted model, serum potassium was a significant predictor of incident diabetes (OR: 0.83; 95% CI: 0.74, 0.92 per SD increment in serum potassium). In multivariable models, we found a significant interaction between serum potassium and aldosterone (P = 0.046). In stratified multivariable models, in those with normal aldosterone (<9 ng/dL, n = 1163), participants in the highest 2 potassium quartiles had significantly lower odds of incident diabetes than did those in the lowest potassium quartile [OR (95% CI): 0.61 (0.39, 0.97) and 0.54 (0.33, 0.90), respectively]. Among those with high-normal aldosterone (≥9 ng/dL, n = 202), we found no significant association between serum potassium and incident diabetes. In these stratified models, serum aldosterone was not a significant predictor of incident diabetes. We found no statistically significant associations between dietary or urinary potassium and incident diabetes.

CONCLUSIONS

In this African-American cohort, we found that aldosterone may modify the association between serum potassium and incident diabetes. In participants with normal aldosterone, high-normal serum potassium was associated with a lower risk of diabetes than was low-normal serum potassium. Additional studies are warranted to determine whether serum potassium is a modifiable risk factor that could be a target for diabetes prevention. This trial was registered at clinicaltrials.gov as NCT00415415.

Separation and dual detection of prostate cancer cells and protein biomarkers using a microchip device

Current efforts for the detection of prostate cancer using only prostate specific antigen are not ideal and indicate a need to develop new assays - using multiple targets - that can more accurately stratify disease states. We previously introduced a device capable of the concurrent detection of cellular and molecular markers from a single sample fluid. Here, an improved design, which achieves affinity as well as size-based separation of captured targets using antibody-conjugated magnetic beads and a silicon chip containing micro-apertures, is presented. Upon injection of the sample, the integration of magnetic attraction with the micro-aperture chip permits larger cell-bead complexes to be isolated in an upper chamber with the smaller protein-bead complexes and remaining beads passing through the micro-apertures into the lower chamber. This enhances captured cell purity for on chip quantification, allows the separate retrieval of captured cells and proteins for downstream analysis, and enables higher bead concentrations for improved multiplexed ligand targeting. Using LNCaP cells and prostate specific membrane antigen (PSMA) to model prostate cancer, the device was able to detect 34 pM of spiked PSMA and achieve a cell capture efficiency of 93% from culture media. LNCaP cells and PSMA were then spiked into diluted healthy human blood to mimic a cancer patient. The device enabled the detection of spiked PSMA (relative to endogenous PSMA) while recovering 85-90% of LNCaP cells which illustrated the potential of new assays for the diagnosis of prostate cancer.

Caveolin 1 Modulates Aldosterone-Mediated Pathways of Glucose and Lipid Homeostasis

Background

Overactivation of the aldosterone and mineralocorticoid receptor (MR) pathway is associated with hyperglycemia and dyslipidemia. Caveolin 1 (cav‐1) is involved in glucose/lipid homeostasis and may modulate MR signaling. We investigated the interplay between cav‐1 and aldosterone signaling in modulating insulin resistance and dyslipidemia in cav‐1–null mice and humans with a prevalent variant in the CAV1 gene.

Methods and Results

In mouse studies, cav‐1 knockout mice exhibited higher levels of homeostatic model assessment of insulin resistance, cholesterol, and resistin and lower ratios of high‐ to low‐density lipoprotein (all P<0.001 versus wild type). Moreover, cav‐1 knockout mice displayed hypertriglyceridemia and higher mRNA levels for resistin, retinol binding protein 4, NADPH oxidase 4, and aldose reductase in liver and/or fat tissues. MR blockade with eplerenone significantly decreased glycemia (P<0.01), total cholesterol (P<0.05), resistin (P<0.05), and described enzymes, with no effect on insulin or triglycerides. In the human study, we analyzed the CAV1 gene polymorphism rs926198 in 556 white participants; 58% were minor allele carriers and displayed higher odds of insulin resistance (odds ratio 2.26 [95% CI 1.40–3.64]) and low high‐density lipoprotein (odds ratio 1.54 [95% CI 1.01–3.37]). Aldosterone levels correlated with higher homeostatic model assessment of insulin resistance and resistin and lower high‐density lipoprotein only in minor allele carriers. CAV1 gene expression quantitative trait loci data revealed lower cav‐1 expression in adipose tissues by the rs926198 minor allele.

Conclusions

Our findings in mice and humans suggested that decreased cav‐1 expression may activate the effect of aldosterone/MR signaling on several pathways of glycemia, dyslipidemia, and resistin. In contrast, hyperinsulinemia and hypertriglyceridemia are likely mediated by MR‐independent mechanisms. Future human studies will elucidate the clinical relevance of MR blockade in patients with genotype‐mediated cav‐1 deficiency.

Aldosterone in vascular and metabolic dysfunction

PURPOSE OF REVIEW

This review will highlight recent developments in mineralocorticoid receptor research which impact aldosterone-associated vascular and cardiometabolic dysfunction.

RECENT FINDINGS

The mineralocorticoid receptor is also expressed in vascular smooth muscle and vascular endothelium, and contributes to vascular function and remodeling. Adipocyte-derived leptin stimulates aldosterone secretion, which may explain the observed link between obesity and hyperaldosteronism. Adipocyte mineralocorticoid receptor overexpression produces systemic changes consistent with metabolic syndrome. Ongoing studies with novel nonsteroidal mineralocorticoid receptor antagonists may provide a novel treatment for diabetic nephropathy and heart failure in patients with chronic kidney disease, with reduced risk of hyperkalemia.

SUMMARY

Ongoing research continues to demonstrate novel roles of the vascular and adipocyte mineralocorticoid receptor function, which may explain the beneficial metabolic and vascular benefits of mineralocorticoid receptor antagonists.

Obesity, Renin-Angiotensin System Blockade and Risk of Adverse Renal Outcomes: A Population-Based Cohort Study

BACKGROUND

Obesity substantially increases the risk of the development of chronic kidney disease. Adipose tissue expresses all of the components of the renin-angiotensin system (RAS), contributing to the high prevalence of hypertension in obese patients and driving renal hyperfiltration and subsequent glomerular injury.

METHODS

We performed a retrospective cohort study using a United Kingdom primary care database, evaluating the effect of time-updated exposure to RAS blockade versus all other antihypertensive medications in obese, hypertensive, non-diabetic patients. We used Cox proportional hazards modeling with and without marginal structural modeling to assess the hazards of developing a primary outcome of 50% reduction in estimated glomerular filtration rate (eGFR) (across 2 consecutive values), end stage renal disease or death.

RESULTS

A total of 219,701 patients met inclusion criteria, with a median 7.2 years of follow-up. Median baseline eGFR was 72.6 ml/min/1.73 m2. Compared to other antihypertensive medications, patients treated with RAS blockade had a modestly elevated hazard of adverse renal outcomes using traditional Cox regression (hazard ratio (HR) 1.04, 95% CI 1.01-1.07) and no significantly increased hazard by marginal structural modeling (HR 1.02, 95% CI 0.97-1.08). Patients treated with RAS blockade had a significantly reduced hazard of incident diabetes, but no significant difference in mortality.

CONCLUSION

This study, conducted in a large real-world cohort, provides evidence that RAS blockade may not provide benefit with regard to longitudinal renal outcomes in obese, hypertensive patients. Further research is needed to elucidate the hemodynamic and renoprotective role of antihypertensive medications in obese patients.

Plasminogen activator inhibitor-1 and type 2 diabetes: a systematic review and meta-analysis of observational studies

An emerging body of evidence has implicated plasminogen activator inhibitor-1 (PAI-1) in the development of type 2 diabetes (T2D), though findings have not always been consistent. We systematically reviewed epidemiological studies examining the association of PAI-1 with T2D. EMBASE, PubMed, Web of Science, and the Cochrane Library were searched to identify studies for inclusion. Fifty-two studies (44 cross-sectional with 47 unique analytical comparisons and 8 prospective) were included. In pooled random-effects analyses of prospective studies, a comparison of the top third vs. bottom third of baseline PAI-1 values generated a RR of T2D of 1.67 (95% CI 1.28–2.18) with moderate heterogeneity (I² = 38%). Additionally, of 47 cross-sectional comparisons, 34(72%) reported significantly elevated PAI-1 among diabetes cases versus controls, 2(4%) reported significantly elevated PAI-1 among controls, and 11(24%) reported null effects. Results from pooled analyses of prospective studies did not differ substantially by study design, length of follow-up, adjustment for various putative confounding factors, or study quality, and were robust to sensitivity analyses. Findings from this systematic review of the available epidemiological literature support a link between PAI-1 and T2D, independent of established diabetes risk factors. Given the moderate size of the association and heterogeneity across studies, future prospective studies are warranted.

Biomarkers of Metabolic Syndrome: Biochemical Background and Clinical Significance

Biomarkers of the metabolic syndrome are divided into four subgroups. Although dividing them in groups has some limitations, it can be used to draw some conclusions. In a first part, the dyslipidemias and markers of oxidative stress are discussed, while inflammatory markers and cardiometabolic biomarkers are reviewed in a second part. For most of them, the biochemical background and clinical significance are discussed, although here also a well-cut separation cannot always be made. Altered levels cannot always be claimed as the cause, risk, or consequence of the syndrome. Several factors are interrelated to each other and act in a concerted, antagonistic, synergistic, or modulating way. Most important conclusions are summarized at the end of every reviewed subgroup. Genetic biomarkers or influences of various food components on concentration levels are not included in this review article.

Aldosterone Predicts Cardiovascular, Renal, and Metabolic Disease in the General Community: A 4-Year Follow-Up

BACKGROUND

We recently reported that normal aldosterone levels are associated with cardiovascular, renal, and metabolic disease in a sample of the US general community (Visit 1). For the current analyses we used the same cohort in a new 4-year follow-up study (Visit 2).

METHODS AND RESULTS

We measured aldosterone at Visit 1 and analyzed its predictive role for new diseases at Visit 2 (n=1140). We measured aldosterone at Visit 2 and investigated its associations with disease at Visit 2 (n=1368). We analyzed aldosterone continuously and we also dichotomized the variable as whether subjects were in the third tertile versus second and first tertiles. As continuous variable at Visit 1, aldosterone predicted new onset hypertension (HTN) (OR=1.36, CI=1.13-1.63, P=0.001), central obesity (OR=1.36, CI=1.07-1.73, P=0.011), and use of lipid-lowering drugs (OR=1.25, CI=1.05-1.48, P=0.012) at Visit 2, after adjustment for age, sex, and body mass index. When in the third tertile (8.5-88.6 ng/dL), aldosterone predicted type 2 diabetes (T2DM, OR=1.96, CI=1.03-3.70, P=0.039). At Visit 2, aldosterone remained associated with HTN, obesity, and chronic kidney disease (CKD), as reported for Visit 1. However, aldosterone was not associated with heart failure (HF) at Visit 1 and 2, nor was aldosterone a predictor of HF between visits.

CONCLUSIONS

Aldosterone predicts new HTN, central obesity, T2DM, and use of lipid-lowering drugs in the general community and remains associated with HTN, obesity, and CKD over 4 years. Aldosterone is not associated nor predicts HF. Further studies are warranted to evaluate aldosterone as therapeutic target in the general community.

A possible role of serum uric acid as a marker of metabolic syndrome

BACKGROUND/AIMS

The association between serum uric acid (SUA) levels and metabolic syndrome (MetS) has recently been reported in several cross-sectional and longitudinal studies. We investigated SUA as a biomarker to predict future development of MetS in healthy Korean men without diabetes or hypertension and determined the optimal cut-off levels of SUA.

METHODS

A retrospective cohort study was conducted using data from healthy men who received a general health check-up in 2003. A total of 1809 participants free of MetS, diabetes and hypertension was enrolled. Participants were classified into three groups based on SUA levels: group 1 (<5.5 mg/dL), group 2 (5.5-6.9 mg/dL) and group 3 (≥7.0 mg/dL).

RESULTS

During 13,802 person-years of follow up, 127 participants developed MetS. After adjusting for multiple associated parameters, SUA was significantly associated with incident MetS (hazard ratios comparing groups 2 and 3 vs group 1, 2.45 and 3.47 respectively; P < 0.001). In receiver operating characteristic curve analysis, the optimal cut-off level for SUA to predict the development of MetS was 6.5 mg/dL.

CONCLUSION

Our results indicate that an increased level of SUA, even within the normal range, is associated with future development of MetS in healthy middle-aged men.

Pharmacological activation of PPAR gamma ameliorates vascular endothelial insulin resistance via a non-canonical PPAR gamma-dependent nuclear factor-kappa B trans-repression pathway

Vascular endothelial insulin resistance (IR) is a critically initial factor in cardiocerebrovascular events resulted from diabetes and is becoming a worldwide public health issue. Thiazolidinediones (TZDs) are clinical insulin-sensitizers acting through a canonical peroxisome proliferator-activated receptor gamma (PPARγ)-dependent insulin trans-activation pathway. However, it remains elusive whether there are other mechanisms. In current study, we investigated whether TZDs improve endothelial IR induced by high glucose concentration or hyperglycemia via a non-canonical PPARγ-dependent nuclear factor-kappa B (NF-κB) trans-repression pathway. Our results showed that pre-treatment with TZDs dramatically decrease the susceptibility of endothelial cell to IR, while post-treatment notably improve the endothelial IR both in vitro and in vivo. Moreover, TZDs substantially increase the levels of endothelial nitric oxide synthase (eNOS) and inhibitory κB alpha (IκBα), whereas decrease those of the phosphorylated inhibitory κB kinase alpha/beta (phosphor-IKKα/β) and the cytokines including tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cellular adhesion molecule-1 (sVCAM-1), suggesting that TZDs act indeed through a PPARγ-dependent NF-κB trans-repression pathway. These findings highlighted a non-canonical mechanism for TZDs to ameliorate endothelial IR which might provide a potential strategy to prevent and treat the diabetic vascular complications clinically.

Crosstalk between red blood cells and the immune system and its impact on atherosclerosis

Atherosclerosis is a chronic multifactorial disease of the arterial wall characterized by inflammation, oxidative stress, and immune system activation. Evidence exists on a pathogenic role of oxidized red blood cells (RBCs) accumulated in the lesion after intraplaque hemorrhage. This review reports current knowledge on the impact of oxidative stress in RBC modifications with the surface appearance of senescent signals characterized by reduced expression of CD47 and glycophorin A and higher externalization of phosphatidylserine. The review summarizes findings indicating that oxidized, senescent, or stored RBCs, due to surface antigen modification and release of prooxidant and proinflammatory molecules, exert an impaired modulatory activity on innate and adaptive immune cells and how this activity contributes to atherosclerotic disease. In particular RBCs from patients with atherosclerosis, unlike those from healthy subjects, fail to control lipopolysaccharide-induced DC maturation and T lymphocyte apoptosis. Stored RBCs, accompanied by shedding of extracellular vesicles, stimulate peripheral blood mononuclear cells to release proinflammatory cytokines, augment mitogen-driven T cell proliferation, and polarize macrophages toward the proinflammatory M1 activation pathway. Collectively, literature data suggest that the crosstalk between RBCs with immune cells represents a novel mechanism by which oxidative stress can contribute to atherosclerotic disease progression and may be exploited for therapeutic interventions.

A new insight into the role of plasma fibrinogen in the development of metabolic syndrome from a prospective cohort study in urban Han Chinese population

BACKGROUND

Elevated levels of fibrinogen may contribute to a prothrombotic state. Cross-sectional studies suggest fibrinogen possibly linked with MetS/its components, while results of cohort studies remain controversial. Thus, this study was designed to identify the association of plasma fibrinogen with metabolic syndrome (MetS) and further to clarify the role of fibrinogen in the development of MetS.

METHODS

A large-scale prospective cohort study was conducted in routine health check-up population. 6209 participants free of MetS at baseline were included in the original cohort, with annually routine health check-up for incident MetS from 2005 to 2011. Then, 4 pre-MetS sub-cohorts, with overweight, hypertension, hyperglycemia and dyslipidemia at baseline respectively, were also created from the original cohort. Various strategies of Cox model analysis were performed for attempting to confirm the role of fibrinogen in the development of MetS.

RESULTS

Total MetS incidence density was 75.58 per 1000 person-years. Cox regression analysis by adjusting for potential confounders as well as four MetS components showed a significant effect of fibrinogen on MetS just in female, with risk ratio (RR) (95 % CI) of 1.48 (1.02, 2.13) for Q4 vs. Q1. Further analysis in the 4 pre-MetS female sub-cohorts revealed this significant effect only in overweight sub-cohort, with RR (95 % CI) of 1.97 (1.20, 3.23), but no significant interaction of overweight with fibrinogen on MetS was revealed in original female cohort. Then, stratification analysis among the 4 sub-groups of fibrinogen quartiles showed that effects of overweight on MetS were different among the 4 sub-groups of fibrinogen quartiles, with RR of 2.98 for Q1, 4.40 for Q2, 3.93 for Q3, and 4.82 for Q4 respectively.

CONCLUSIONS

Fibrinogen was associated with MetS just in overweight sub-cohort of female individuals, and fibrinogen might be a potential modifier in the pathway from overweight to MetS.

Mineralocorticoid receptor in adipocytes and macrophages: a promising target to fight metabolic syndrome

Aldosterone is the primary ligand for the mineralocorticoid receptor (MR) and has been considered long time a "renal" hormone, acting at this site as a key regulator of plasma volume, electrolyte homeostasis and blood pressure. A new exciting era of MR biology began with the identification of MR in different non-epithelial tissues such as brain, heart, vessels, macrophages/monocytes, and adipose tissue. The distribution of MR in such a wide range of tissues has suggested novel and unexpected roles for MR, for example in energy metabolism and inflammation. An increasing body of evidence suggests a detrimental effect of aldosterone excess on the development of metabolic alterations. Disturbances in glucose metabolism due to inappropriate activation of MR are frequently observed in patients with primary aldosteronism as well as in obese subjects. MR antagonists have beneficial effects on glucose tolerance and metabolic parameters in experimental animals, whereas their role in humans remains unclear. The aim of this review is to discuss the pathophysiology of MR activation in experimental models, particularly at the level of adipocytes and macrophages, to discuss novel and sometimes contrasting insights from emerging studies, and to highlight deficiencies in the field.

Role of homocysteinylation of ACE in endothelial dysfunction of arteries

The direct impact of de novo synthesis of homocysteine (Hcy) and its reactive metabolites, Hcy-S-S-Hcy and Hcy thiolactone (HCTL), on vascular function has not been fully elucidated. We hypothesized that Hcy synthesized within endothelial cells affects activity of angiotensin-converting enzyme (ACE) by direct homocysteinylation of its amino- and/or sulfhydryl moieties. This covalent modification enhances ACE reactivity toward angiotensin II (ANG II)-NADPH oxidase-superoxide-dependent endothelial dysfunction. Mesenteric and coronary arteries isolated from normal rats were incubated for 3 days with or without exogenous methionine (Met, 0.1-0.3 mM), a precursor to Hcy. Incubation of arteries in Met-free media resulted in time-dependent decreases in vascular Hcy formation. By contrast, vessels incubated with Met produced Hcy in a dose-dependent manner. There was a notably greater de novo synthesis of Hcy from endothelial than from smooth muscle cells. Enhanced levels of Hcy production significantly impaired shear stress-induced dilation and release of nitric oxide, events that are associated with elevated production of vascular superoxide. Each of these processes was attenuated by ANG II type I receptor blocker or ACE and NADPH oxidase inhibitors. In addition, in vitro exposure of purified ACE to Hcy-S-S-Hcy/HCTL resulted in formation of homocysteinylated ACE and an enhanced ACE activity. The enhanced ACE activity was confirmed in isolated coronary and mesenteric arteries that had been exposed directly to Hcy-S-S-Hcy/HCTL or after Met incubation. In conclusion, vasculature-derived Hcy initiates endothelial dysfunction that, in part, may be mediated by ANG II-dependent activation of NADPH oxidase in association with homocysteinylation of ACE.

Circulating aldosterone and natriuretic peptides in the general community: relationship to cardiorenal and metabolic disease

We sought to investigate the role of aldosterone as a mediator of disease and its relationship with the counter-regulatory natriuretic peptide (NP) system. We measured plasma aldosterone (n=1674; aged≥45 years old) in a random sample of the general population from Olmsted County, MN. In a multivariate logistic regression model, aldosterone analyzed as a continuous variable was associated with hypertension (odds ratio [OR]=1.75; 95% confidence interval [CI]=1.57-1.96; P<0.0001), obesity (OR=1.34; 95% CI=1.21-1.48; P<0.0001), chronic kidney disease (OR=1.39; 95% CI=1.22-1.60; P<0.0001), central obesity (OR=1.47; 95% CI=1.32-1.63; P<0.0001), metabolic syndrome (OR=1.41; 95% CI=1.26-1.58; P<0.0001), high triglycerides (OR=1.23; 95% CI=1.11-1.36; P<0.0001), concentric left ventricular hypertrophy (OR=1.22; 95% CI=1.09-1.38; P=0.0007), and atrial fibrillation (OR=1.24; 95% CI=1.01-1.53; P=0.04), after adjusting for age and sex. The associations with hypertension, central obesity, metabolic syndrome, triglycerides, and concentric left ventricular hypertrophy remained significant after further adjustment for body mass index, NPs, and renal function. Furthermore, aldosterone in the highest tertile correlated with lower NP levels and increased mortality. Importantly, most of these associations remained significant even after excluding subjects with aldosterone levels above the normal range. In conclusion, we report that aldosterone is associated with hypertension, chronic kidney disease, obesity, metabolic syndrome, concentric left ventricular hypertrophy, and lower NPs in the general community. Our data suggest that aldosterone, even within the normal range, may be a biomarker of cardiorenal and metabolic disease. Further studies are warranted to evaluate a therapeutic and preventive strategy to delay the onset and progression of disease, using mineralocorticoid antagonists or chronic NP administration in high-risk subjects identified by plasma aldosterone.

Relationship between aldosterone and the metabolic syndrome in patients with obstructive sleep apnea hypopnea syndrome: effect of continuous positive airway pressure treatment

Background

Metabolic syndrome (MS) occurs frequently in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). We hypothesized that aldosterone levels are elevated in OSAHS and associated with the presence of MS.

Methods

We studied 66 patients with OSAHS (33 with MS and 33 without MS) and 35 controls. The occurrence of the MS was analyzed according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) clinical criteria. Measurements of plasma renin activity (PRA), aldosterone, aldosterone:PRA ratio, creatinine, glucose, triglycerides, cholesterol and HDL cholesterol were obtained at baseline and after CPAP treatment.

Results

Aldosterone levels were associated with the severity of OSAHS and higher than controls (p = 0.046). Significant differences in aldosterone levels were detected between OSAHS patients with and without MS (p = 0.041). A significant reduction was observed in the aldosterone levels in patients under CPAP treatment (p = 0.012).

Conclusion

This study shows that aldosterone levels are elevated in OSAHS in comparison to controls, and that CPAP therapy reduces aldosterone levels. It also shows that aldosterone levels are associated with the presence of metabolic syndrome, suggesting that aldosterone excess might predispose or aggravate the metabolic and cardiovascular complications of OSAHS.

Trial registration

The study is not a randomized controlled trial and was not registered.

Changes in serum aldosterone are associated with changes in obesity-related factors in normotensive overweight and obese young adults

Recent data suggest excess circulating aldosterone promotes cardiometabolic decline. Weight loss may lower aldosterone levels, but little longitudinal data is available in normotensive adults. We aimed to determine whether, independent of changes in sodium excretion, reductions in serum aldosterone are associated with favorable changes in obesity-related factors in normotensive overweight/obese young adults. We studied 285 overweight/obese young adult participants (body mass index ≥ 25 and<40 kg m⁻², age 20-45 years) in a clinical trial examining the effects of a 1-year diet and physical activity intervention with or without sodium restriction on vascular health. Body weight, serum aldosterone, 24-h sodium and potassium excretion and obesity-related factors were measured at baseline, 6, 12 and 24 months. Weight loss was significant at 6 (7%), 12 (6%) and 24 months (4%; all P<0.0001). Decreases in aldosterone were associated with decreases in C-reactive protein, leptin, insulin, homeostasis assessment of insulin resistance, heart rate, tonic cardiac sympathovagal balance and increases in adiponectin (all P<0.05) in models adjusting for baseline age, sex, race, intervention arm, time since baseline, and sodium and potassium excretion. Weight loss and reductions in thigh intermuscular fat (intermuscular adipose tissue area; IMAT) were associated with decreases in aldosterone in the subgroup (n=98) with metabolic syndrome (MetS) at baseline (MetS × weight loss, P=0.04; MetS × change in IMAT, P=0.04). Favorable changes in obesity-related factors are associated with reductions in aldosterone in young adults with no risk factors besides excess weight, an important finding, given aldosterone's emergence as an important cardiometabolic risk factor.

Aldosterone, C-reactive protein, and plasma B-type natriuretic peptide are associated with the development of metabolic syndrome and longitudinal changes in metabolic syndrome components: findings from the Jackson Heart Study

OBJECTIVE

Several pathomechanisms are implicated in the pathogenesis of metabolic syndrome (MetS), most of which have not been investigated in African Americans (AAs). We examined the contribution of a selected panel of biomarkers to the development of MetS in Jackson Heart Study (JHS) participants in this investigation.

RESEARCH DESIGN AND METHODS

We evaluated 3,019 JHS participants (mean age, 54 years; 64% women) with measurements for seven biomarkers representing inflammation (high-sensitivity C-reactive protein [CRP]), adiposity (leptin), natriuretic pathway (B-natriuretic peptide [BNP]), adrenal pathway (cortisol and aldosterone), and endothelial function (endothelin and homocysteine). We related the biomarker panel to the development of MetS on follow-up and to longitudinal changes in MetS components.

RESULTS

There were 278 (22.9%) of 1,215 participants without MetS at baseline who had development of new-onset MetS at follow-up. The incidence of MetS was significantly associated with serum aldosterone (P=0.004), CRP (P=0.03), and BNP (P for trend=0.005). The multivariable-adjusted odds ratios (95% CI) per SD increment of log biomarker were as follows: 1.25 (1.07-1.45) for aldosterone, 1.20 (1.02-1.43) for CRP, and 1.54 (1.07-2.23) and 1.91 (1.31-2.80) for low and high BNP quartiles, respectively. Aldosterone was positively associated with change in all MetS risk components, except low HDL cholesterol and waist circumference. CRP concentration was significantly and directly associated with change in systolic blood pressure (SBP) and waist circumference but inversely associated with HDL cholesterol. For BNP, we observed a U-shape relation with SBP and triglycerides.

CONCLUSIONS

Our analysis confirms that, in AAs, higher circulating aldosterone and CRP concentrations predict incident MetS. The nonlinear U-shape relation of BNP with MetS and its components has not been reported before and thus warrants replication.

Area-level socioeconomic characteristics and incidence of metabolic syndrome: a prospective cohort study

BACKGROUND

The evidence linking socioeconomic environments and metabolic syndrome (MetS) has primarily been based on cross-sectional studies. This study prospectively examined the relationships between area-level socioeconomic position (SEP) and the incidence of MetS.

METHODS

A prospective cohort study design was employed involving 1,877 men and women aged 18+ living in metropolitan Adelaide, Australia, all free of MetS at baseline. Area-level SEP measures, derived from Census data, included proportion of residents completing a university education, and median household weekly income. MetS, defined according to International Diabetes Federation, was ascertained after an average of 3.6 years follow up. Associations between each area-level SEP measure and incident MetS were examined by Poisson regression Generalised Estimating Equations models. Interaction between area- and individual-level SEP variables was also tested.

RESULTS

A total of 156 men (18.7%) and 153 women (13.1%) developed MetS. Each percentage increase in the proportion of residents with a university education corresponded to a 2% lower risk of developing MetS (age and sex-adjusted incidence risk ratio (RR)=0.98; 95% confidence interval (CI) =0.97-0.99). This association persisted after adjustment for individual-level income, education, and health behaviours. There was no significant association between area-level income and incident MetS overall. For the high income participants, however, a one standard deviation increase in median household weekly income was associated with a 29% higher risk of developing MetS (Adjusted RR=1.29; 95%CI=1.04-1.60).

CONCLUSIONS

While area-level education was independently and inversely associated with the risk of developing MetS, the association between area-level income and the MetS incidence was modified by individual-level income.

The renin angiotensin aldosterone system and insulin resistance in humans

Alterations in the renin angiotensin aldosterone system (RAAS) contribute to the underlying pathophysiology of insulin resistance in humans; however, individual differences in the treatment response of insulin resistance to RAAS blockade persist. Thus, understanding inter-individual differences in the relationship between the RAAS and insulin resistance may provide insights into improved personalized treatments and improved outcomes. The effects of the systemic RAAS on blood pressure regulation and glucose metabolism have been studied extensively; however, recent discoveries on the influence of local tissue RAAS in the skeletal muscle, heart, vasculature, adipocytes, and pancreas have led to an improved understanding of how activated tissue RAAS influences the development of insulin resistance and diabetes in humans. Angiotensin II (ANGII) is the predominant RAAS component contributing to insulin resistance; however, other players such as aldosterone, renin, and ACE2 are also involved. This review examines the role of local ANGII activity on insulin resistance development in skeletal muscle, adipocytes, and pancreas, followed by a discussion of the other RAAS components implicated in insulin resistance, including ACE2, Ang1-7, renin, and aldosterone.

Aldosterone excess impairs first phase insulin secretion in primary aldosteronism

CONTEXT

Primary aldosteronism (PA) represents the most frequent cause of secondary arterial hypertension. Conflicting data have been published regarding the effect of aldosterone excess on glucose metabolism.

OBJECTIVE

Our aim was to analyze insulin sensitivity and β-cell function in a cohort of PA patients. Prospective follow-up investigations were performed in a subgroup of patients before and after adrenalectomy to assess the metabolic outcome.

DESIGN

Oral glucose tolerance test, combined intravenous glucose tolerance test, hyperinsulinemic-euglycemic glucose clamp test, and arginine test were carried out after a 12-hour fasting period.

PATIENTS

Twenty-two consecutive patients with both unilateral aldosterone-producing adenoma and bilateral idiopathic adrenal hyperplasia were recruited through the Munich center of the German Conn's Registry. The control group of patients with essential hypertension (n = 11) of corresponding age and body mass index was recruited from our hypertension unit. A normotensive cohort (n = 11) served as a further control group.

RESULTS

At baseline, first-phase insulin reaction in intravenous glucose tolerance test was significantly reduced in patients with PA as compared to normal controls (36.0 [24.0; 58.7] vs 90.1 [52.6; 143.8] μU/mL, P = .031) and lower in comparison to essential hypertension without reaching statistical significance (53.2 [30.8; 73.3] μU/mL, P = .123). The study was repeated 6 months after unilateral adrenalectomy in 9 consecutive patients with aldosterone-producing adenoma. At this time point, blood pressure had been normalized in most of the patients while body mass index remained unchanged (26.9 [25.5; 37.6] vs 27.5 [25.1; 35.6] kg/m(2), P = .401). First-phase insulin reaction in response to glucose significantly increased at follow-up (from 36.0 [25.5; 58.7] to 48.5 [40.4; 95.2] μU/mL, P = .038, n = 9). In contrast, insulin sensitivity and response to iv arginine did not differ before and after adrenalectomy.

CONCLUSION

Aldosterone excess has a direct negative effect on β-cell function in patients with PA. After adrenalectomy, glucose-induced first-phase insulin secretion improves significantly in the patients.

Development of metabolic syndrome components in adults with a healthy obese phenotype: a 3-year follow-up

OBJECTIVE

There is a lack of data on the progression from a healthy obese phenotype toward an unhealthy obese phenotype and the development of metabolic syndrome (MetS). Our aim was to assess the development of MetS 3 years after screening in centrally obese individuals with a healthy obese phenotype and to evaluate the usefulness of repeated screening.

DESIGN AND METHODS

Eighty-eight individuals (mean age 47 years, 88% female) with central obesity as their only MetS component (ATP III criteria) at baseline screening were re-evaluated for MetS status after 3 years.

RESULTS

At follow-up, the cardiometabolic risk profile in centrally obese individuals with a healthy phenotype showed a tendency toward deterioration. Thirty-two percent developed at least one additional MetS component, 7% had developed MetS. Nobody had developed type 2 diabetes. An increased triglyceride level (n = 16) and an increased blood pressure (n = 18) were the components most often present at follow-up. The people developing additional MetS components had a lower education level compared with the group that preserved the healthy centrally obese phenotype (80 vs. 71% lower educated, P = 0.35). They also had slightly worse baseline levels of the risk factors.

CONCLUSION

The number of centrally obese individuals developing an unhealthy phenotype in this relatively short follow-up period emphasizes the need for a regular surveillance of cardiometabolic parameters in centrally obese individuals. However, it is questionable whether a repeated screening for type 2 diabetes every 3 years, as recommended by the American Diabetes Association, in this category of patients is appropriate.

Aldosterone deficiency prevents high-fat-feeding-induced hyperglycaemia and adipocyte dysfunction in mice

AIMS/HYPOTHESIS

Obesity is associated with aldosterone excess, hypertension and the metabolic syndrome, but the relative contribution of aldosterone to obesity-related complications is debated. We previously demonstrated that aldosterone impairs insulin secretion, and that genetic aldosterone deficiency increases glucose-stimulated insulin secretion in vivo. We hypothesised that elimination of endogenous aldosterone would prevent obesity-induced insulin resistance and hyperglycaemia.

METHODS

Wild-type and aldosterone synthase-deficient (As (-/-)) mice were fed a high-fat (HF) or normal chow diet for 12 weeks. We assessed insulin sensitivity and insulin secretion using clamp methodology and circulating plasma adipokines, and examined adipose tissue via histology.

RESULTS

HF diet induced weight gain similarly in the two groups, but As (-/-) mice were protected from blood glucose elevation. HF diet impaired insulin sensitivity similarly in As (-/-) and wild-type mice, assessed by hyperinsulinaemic-euglycaemic clamps. Fasting and glucose-stimulated insulin were higher in HF-fed As (-/-) mice than in wild-type controls. Although there was no difference in insulin sensitivity during HF feeding in As (-/-) mice compared with wild-type controls, fat mass, adipocyte size and adiponectin increased, while adipose macrophage infiltration decreased. HF feeding significantly increased hepatic steatosis and triacylglycerol content in wild-type mice, which was attenuated in aldosterone-deficient mice.

CONCLUSIONS/INTERPRETATION

These studies demonstrate that obesity induces insulin resistance independently of aldosterone and adipose tissue inflammation, and suggest a novel role for aldosterone in promoting obesity-induced beta cell dysfunction, hepatic steatosis and adipose tissue inflammation.

Abnormal aldosterone physiology and cardiometabolic risk factors

Abnormal aldosterone physiology has been implicated in the pathogenesis of cardiometabolic diseases. Single aldosterone measurements capture only a limited range of aldosterone physiology. New methods of characterizing aldosterone physiology may provide a more comprehensive understanding of its relationship with cardiometabolic disease. We evaluated whether novel indices of aldosterone responses to dietary sodium modulation, the sodium-modulated aldosterone suppression-stimulation index (SASSI for serum and SAUSSI for urine), could predict cardiometabolic risk factors. We performed cross-sectional analyses on 539 subjects studied on liberal and restricted sodium diets with serum and urinary aldosterone measurements. SASSI and SAUSSI were calculated as the ratio of aldosterone on liberal (maximally suppressed aldosterone) to the aldosterone on restricted (stimulated aldosterone) diets and associated with risk factors using adjusted regression models. Cardiometabolic risk factors associated with either impaired suppression of aldosterone on liberal diet, or impaired stimulation on restricted diet, or both; in all of these individual cases, these risk factors associated with higher SASSI or SAUSSI. In the context of abnormalities that constitute the metabolic syndrome, there was a strong positive association between the number of metabolic syndrome components (0-4) and both SASSI and SAUSSI (P<0.0001) that was independent of known aldosterone secretagogues (angiotensin II, corticotropin, potassium). SASSI and SAUSSI exhibited a high sensitivity in detecting normal individuals with zero metabolic syndrome components (86% for SASSI and 83% for SAUSSI). Assessing the physiological range of aldosterone responses may provide greater insights into adrenal pathophysiology. Dysregulated aldosterone physiology may contribute to, or result from, early cardiometabolic abnormalities.

Vascular actions of aldosterone

Aldosterone exerts direct effects on the vascular system by inducing oxidative stress, inflammation, hypertrophic remodeling, fibrosis, and endothelial dysfunction. Aldosterone exerts its effects through genomic and nongenomic pathways in a mineralocorticoid receptor (MR)-dependent or independent manner. Other aldosterone receptors such as GPR30 have been identified. A tight relation exists between the aldosterone and angiotensin II pathways, as well as with the endothelin-1 system. There is a correlation between plasma levels of aldosterone and cardiovascular risk. Recently, an increasing body of evidence has underlined the importance of aldosterone in cardiovascular complications associated with the metabolic syndrome, such as arterial remodeling and endothelial dysfunction. Blockade of MR is an increasingly used evidence-based therapy for many forms of cardiovascular disease, including hypertension, heart failure, chronic kidney disease, and diabetes mellitus.

Alterations in the QRS complex in the offspring of patients with metabolic syndrome and diabetes mellitus: early evidence of cardiovascular pathology

OBJECTIVE

This study was undertaken to evaluate the nature and onset of changes in the QRS complex in the offspring of patients with diabetes mellitus (DM) and metabolic syndrome (MetS).

METHODS AND METHODS

A total of 529 subjects, divided into 5 groups, were included in the study: (i) group DM (n = 92), patients with DM; (ii) group MetS (n = 125), patients with MetS; (iii) group O-DM (n = 109), offspring of patients with DM; (iv) group O-MetS (n = 122), offspring of patients with MetS; and (v) group HO (n = 81), offspring of healthy subjects. QRS parameters analyzed included amplitude, maximum QRS spatial vector magnitude, electrical axis (EA), and 3 electrocardiogram (ECG) criteria for left ventricular hypertrophy based on amplitude criteria: Sokolow-Lyon index, Cornell voltage, and Gubner criterion.

RESULTS

Patients with DM and MetS showed a significant leftward shift of the EA when compared with the control group. A modest but significant leftward shift of EA was also observed in both offspring groups. These EA and maximum QRS spatial vector magnitude changes were reflected in the individual leads of the 12-lead ECG. The prevalence of a positive diagnosis by accepted electrocardiographic criteria (ECG left ventricular hypertrophy) was low.

CONCLUSION

Patients with DM and MetS displayed significant changes in QRS complex that suggest depolarization sequence deterioration. Similar changes were observed also in the offspring of patients with DM and MetS, which suggests early subclinical cardiovascular damage. These findings have implications for prevention, early diagnosis, and treatment in the offspring of patients with DM and MetS.

Role of mineralocorticoid receptor in insulin resistance

PURPOSE OF REVIEW

Recent data suggest that mineralocorticoid receptor activation can affect insulin resistance independent of its effects on blood pressure. This review discusses new evidence linking mineralocorticoid receptor to insulin resistance and the underlying mechanisms of these effects.

RECENT FINDINGS

Observational studies have shown mineralocorticoid activity to be associated with insulin resistance irrespective of race, blood pressure or body weight. Increased mineralocorticoid activity may be the common link between obesity, hypertension, dyslipidemia and insulin resistance, features that make up the metabolic syndrome. Treatment of primary aldosteronism is associated with a decrease in insulin resistance and provides one of the most convincing evidences in favor of the contribution of mineralocorticoid receptor to insulin resistance. Dietary salt restriction, which increases aldosterone levels, is also associated with an increase in insulin resistance. Potential mechanisms by which mineralocorticoid receptor may contribute to insulin resistance include a decreased transcription of the insulin receptor gene, increased degradation of insulin receptor substrates, interference with insulin signaling mechanisms, decreased adiponectin production and increased oxidative stress and inflammation. Advantages of mineralocorticoid receptor antagonists on insulin resistance have been demonstrated in animal models.

SUMMARY

There may be a benefit of mineralocorticoid receptor antagonists in human insulin resistance states, but more clinical research is needed to explore these possibilities.

Genes implicated in insulin resistance are down-regulated in primary aldosteronism patients

Primary aldosteronism (PA) patients display an increased incidence of insulin resistance. Herein we demonstrate the decreased gene expression of lipid metabolism genes PCK1, PLIN, ADIPOQ and PPARG in the visceral adipose tissue (VAT) of PA patients compared to age-, sex- and BMI-matched controls. In VAT, the expression of PCK1, PLIN, ADIPOQ and PPARG was inversely correlated with aldosterone levels; furthermore, PLIN and ADIPOQ gene expression was correlated with potassium levels. Therefore, raised aldosterone and low potassium may contribute to the reduced expression of these genes in PA patients. Finally, incubation of primary cultures of human adipocytes with aldosterone resulted in a decrease in the expression of PCK1, PLIN and ADIPOQ and this effect was blocked by eplerenone. Therefore, the characteristic aldosterone excess of PA patients may mediate the down-regulation of PCK1, PLIN and ADIPOQ in VAT that in turn may contribute to the insulin resistance observed in PA patients.

Mineralocorticoid receptors in the pathophysiology of chronic kidney diseases and the metabolic syndrome

Recent studies indicate that aldosterone/mineralocorticoid receptor (MR) is a major contributor of chronic kidney disease (CKD) progression. Aldosterone/MR induces glomerular podocyte injury, causing the disruption of the glomerular filtration barrier and proteinuria. Conversely, MR antagonists substantially reduce proteinuria, which can be partly attributable to the protective effects on podocytes. Aldosterone excess, caused by adipocyte-derived aldosterone-releasing factors and other mechanisms, can be pathologically important in the renal complication of metabolic syndrome. A rat model of metabolic syndrome exhibits podocyte injury and proteinuria with serum aldosterone elevation, and the renal damage is prevented by MR blockade. Accumulating data also indicate that MR inhibition can confer renoprotection in a subgroup with low or normal aldosterone levels. We have recently identified the cross-talk between MR and small GTPase Rac1, providing one theoretical basis for the renoprotective effects of MR antagonists in non-high-aldosterone subjects. MR blockade can be a promising strategy for preventing CKD progression, and future clinical trials will conclusively determine the efficacy and tolerability of selective MR inhibition in CKD and metabolic syndrome.

The role of the mineralocorticoid receptor in adipocyte biology and fat metabolism

Aldosterone controls blood pressure by binding to the mineralocorticoid receptor (MR), a ligand-activated transcription factor which regulates critical genes controlling salt and water homeostasis in the kidney. In recent years, inappropriate MR activation has been shown to trigger deleterious responses in various tissues, including vessels, heart and brain, hence promoting vascular inflammation, cardiovascular remodeling, endothelial dysfunction, and oxidative stress. Moreover, epidemiological studies have shown a clear association between aldosterone levels and the incidence of metabolic syndrome. In particular, recent work has revealed functional MRs in adipose tissue, where they mediate the effects of aldosterone and glucocorticoids, displaying important and specific functions involving adipose differentiation, expansion and proinflammatory capacity. This recent evidence finally moved MR out of the shadow of the glucocorticoid receptor (GR), which had previously been considered the only player mediating corticosteroid action in adipose tissue. This has opened a new era of research focusing on the complexity and selectivity of MR function in adipocyte biology. The aim of this review is to summarize the latest concepts on the role of MR in white and brown adipocytes, and to discuss the potential benefits of tissue-selective MR blockade in the treatment of obesity and metabolic syndrome.

Differential effects of nebivolol and metoprolol on insulin sensitivity and plasminogen activator inhibitor in the metabolic syndrome

Early-generation β-blockers lower blood pressure and reduce cardiovascular morality in coronary artery disease and congestive heart failure but worsen glucose homeostasis and fibrinolytic balance. Nebivolol is a third-generation β-blocker that increases the bioavailability of nitric oxide. We compared the effect of nebivolol (5 mg/d) and the β(1)-selective antagonist metoprolol (100 mg/d) on glucose homeostasis and markers of fibrinolysis in 46 subjects with metabolic syndrome. Subjects underwent a frequently sampled IV glucose tolerance test after 3-week washout and placebo treatment and after randomized treatment with study drug. After 12-week treatment, nebivolol and metoprolol equivalently decreased systolic blood pressure, diastolic blood pressure, and heart rate. Neither drug affected β-cell function, disposition index, or acute insulin response to glucose. Metoprolol significantly decreased the insulin sensitivity index. In contrast, nebivolol did not affect insulin sensitivity, and the decrease in sensitivity was significantly greater after metoprolol than after nebivolol (-1.5±2.5×10(-4)×min(-1) per milliunit per liter versus 0.04±2.19×10(-4)×min(-1) per milliunit per liter after nebivolol; P=0.03). Circulating plasminogen activator inhibitor also increased after treatment with metoprolol (from 9.8±6.8 to 12.3±7.8 ng/mL) but not nebivolol (from 10.8±7.8 to 10.5±6.2 ng/mL; P=0.05 versus metoprolol). Metoprolol, but not nebivolol, increased F(2)-isoprostane concentrations. In summary, treatment with metoprolol decreased insulin sensitivity and increased oxidative stress and the antifibrinolytic plasminogen activator inhibitor 1 in patients with metabolic syndrome, whereas nebivolol lacked detrimental metabolic effects. Large clinical trials are needed to compare effects of nebivolol and the β(1) receptor antagonist metoprolol on clinical outcomes in patients with hypertension and the metabolic syndrome.

Mechanisms linking obesity to hypertension

Obesity-related hypertension is increasingly recognized as a distinct hypertensive phenotype requiring a modified approach to diagnosis and management. In this review rapidly evolving insights into the complex and interdependent mechanisms linking obesity to hypertension are discussed. Overweight and obesity are associated with adipose tissue dysfunction, characterized by enlarged hypertrophied adipocytes, increased infiltration by macrophages and marked changes in secretion of adipokines and free fatty acids. This results in chronic vascular inflammation, oxidative stress, activation of the renin-angiotensin-aldosterone system and sympathetic overdrive, eventually leading to hypertension. These mechanisms may provide novel targets for anti-hypertensive drug treatment. Recognition of obesity-related hypertension as a distinct diagnosis enables tailored therapy in clinical practice. This includes lifestyle modification and accommodated choice of blood pressure-lowering drugs.

On the role of autophagy in human diseases: a gender perspective

Cytopathological features of cells from males and females, i.e. XX and XY isolated cells, have been demonstrated to represent a key variable in the mechanism underlying gender disparity in human diseases. Major insights came from the studies of gender differences in cell fate, e.g. in apoptotic susceptibility. We report here some novel insights recently emerged from literature that are referred as to a cytoprotection mechanism by which cells recycle cytoplasm and dispose of excess or defective organelles, i.e. autophagy. Autophagy and related genes have first been identified in yeast. Orthologue genes have subsequently been found in other organisms, including human beings. This stimulated the research in the field and, thanks to the use of molecular genetics and cell biology in different model systems, autophagy gained the attention of several research groups operating to analyse the pathogenetic mechanisms of human diseases. It remains unclear, however, whether autophagy can exert a protective effect or instead contribute to the pathogenesis of important human diseases. On the basis of the growing importance of sex/gender as key determinant of human pathology and of the known differences between males and females in the onset, progression, drug susceptibility and outcome of a plethora of diseases, the idea that autophagy could represent key and critical factor should be taken into account. In the review, we summarize our current knowledge about the role of autophagy in some paradigmatic human diseases (cancer, neurodegenerative, autoimmune, cardiovascular) and the role of ‘cell sex’ differences in this context.

Redox imbalance of red blood cells impacts T lymphocyte homeostasis: implication in carotid atherosclerosis

Oxidative stress and immune/inflammatory responses are key pathogenetic factors of atherosclerotic disease. In this contest, mechanisms that regulate survival and death of immune cells may be relevant. Previous studies have demonstrated that red blood cells (RBCs) are physiologically able to inhibit apoptosis and to promote proliferation of activated T lymphocytes from healthy subjects. The aim of the present study was to evaluate whether RBCs from patients with carotid atherosclerosis maintain their property to modulate T cell homeostasis. Peripheral blood lymphocytes (PBLs) obtained from healthy subjects were activated in vitro by phytohemagglutinin in the presence/absence of RBCs from patients with carotid atherosclerosis or of in vitro oxidised RBCs from healthy subjects. Levels of reactive oxygen species (ROS) and aging markers of RBCs as well as susceptibility to apoptosis of PBLs were evaluated by flow cytometry. PBL proliferation was evaluated by 3H-methyl-thymidine incorporation assay whereas secretion of cytokines, analysed in view of their key role in T cell function, was assessed by ELISA. Levels of ROS and phosphatidyl-serine externalisation, a sign of RBC aging, resulted significantly higher in RBCs from patients than in those from healthy subjects, whereas surface glycophorin A expression and reduced glutathione content did the opposite. Unlike RBCs obtained from healthy subjects, RBCs from patients and in vitro oxidised RBCs did not protect activated T lymphocytes from apoptosis. Hence, RBCs from patients with carotid atherosclerosis, probably due to their oxidative imbalance, impact T cell integrity and function. Our results suggest a new regulatory role for RBCs in atherosclerosis.