New developments in mechanisms of obesity-induced hypertension: role of adipose tissue

Visceral adipose tissue and risk of diabetic nephropathy: A Mendelian randomization study

OBJECTIVE

Previous observational studies have established a correlation between visceral adipose tissue (VAT) and diabetic nephropathy (DN). However, the causality of this association remains unclear. Therefore, the aim of this study was to investigate the causal association between VAT and DN by employing two-sample Mendelian randomization (MR) methods.

METHODS

The primary MR approach employed was the random-effects inverse-variance weighted (IVW) method. Additionally, we employed alternative methods, including the weighted median (WM) approach, MR-Egger regression, and Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO). Sensitivity analyses were conducted to evaluate the robustness of the MR analyses.

RESULTS

Genetically predicted higher VAT mass was causally associated with a higher risk of DN. The results of the MR analyses were as follows: IVW(Beta = 0.948, odds ratio (OR) = 2.581, 95 % confidence interval (CI) = 2.100-3.173, p = 1.980e-19), WM (Beta = 1.126, OR = 3.082, 95 % CI = 2.278-4.171, p = 2.997e-13), MR-Egger (Beta = 1.315, OR = 3.724, 95 % CI = 1.981-6.998, p = 6.446e-05), and MR-PRESSO (Beta = 0.914, OR = 2.493, 95 % CI = 2.292-2.695, p = 3.121e-16). No pleiotropy was detected (p = 0.230).

CONCLUSIONS

This study provided genetic evidence that higher VAT mass was causally associated with a higher risk of DN.

Sex-Specific Changes in Body Composition Following Metabolic and Bariatric Surgery Are Associated with the Remission of Metabolic Syndrome

PURPOSE

Metabolic and bariatric surgery (MBS) is the most effective treatment for metabolic syndrome (MetS). However, the mechanism of MetS remission after MBS remains unclear. We aimed to explore the relationship between sex differences, body composition, and the remission of MetS after MBS.

MATERIALS AND METHODS

Cross-sectional study of 80 patients with obesity and MetS who underwent MBS with case-control design. The International Diabetes Federation criteria were used to define MetS. Body composition was measured using dual-energy X-ray absorptiometry before and 1 year after the operation. In addition to calculating changes in MetS and its prevalence, we performed a multiple logistic regression to determine predictors of MetS remission.

RESULTS

There were significant differences in body composition between males and females after MBS. Both males and females had significant improvements in the overall prevalence of MetS, decreasing from 100 to 21.74% (P <0.001) and from 100 to 35.29% (P <0.001), respectively. A higher percentage of visceral adipose tissue (VAT) reduction tends to be associated with a higher chance of MetS remission in men. In females, the MetS nonremission subgroup had a higher %Trunk lean body mass (LBM), and %Android LBM reduction than the remission subgroup, but the multiple logistic regression analysis result was not statistically significant.

CONCLUSION

After MBS, reduced VAT might be related to MetS reversibility in males, while reduced LBM may result in MetS nonremission in females.

Visceral adipose tissue and residual cardiovascular risk: a pathological link and new therapeutic options

Obesity is a heterogeneous disease that affects almost one-third of the global population. A clear association has been established between obesity and cardiovascular disease (CVD). However, CVD risk is known to be related more to the local distribution of fat than to total body fat. Visceral adipose tissue (VAT) in particular has a high impact on CVD risk. This manuscript reviews the role of VAT in residual CV risk and the available therapeutic strategies for decreasing residual CV risk related to VAT accumulation. Among the many pathways involved in residual CV risk, obesity and particularly VAT accumulation play a major role by generating low-grade systemic inflammation, which in turn has a high prognostic impact on all-cause mortality and myocardial infarction. In recent years, many therapeutic approaches have been developed to reduce body weight. Orlistat was shown to reduce both weight and VAT but has low tolerability and many drug-drug interactions. Naltrexone-bupropion combination lowers body weight but has frequent side effects and is contraindicated in patients with uncontrolled hypertension. Liraglutide and semaglutide, glucagon-like peptide 1 (GLP-1) agonists, are the latest drugs approved for the treatment of obesity, and both have been shown to induce significant body weight loss. Liraglutide, semaglutide and other GLP-1 agonists also showed a positive effect on CV outcomes in diabetic patients. In addition, liraglutide showed to specifically reduce VAT and inflammatory biomarkers in obese patients without diabetes. GLP-1 agonists are promising compounds to limit inflammation in human visceral adipocytes.

Artificial intelligence and abdominal adipose tissue analysis: a literature review

Body composition imaging relies on assessment of tissues composition and distribution. Quantitative data provided by body composition imaging analysis have been linked to pathogenesis, risk, and clinical outcomes of a wide spectrum of diseases, including cardiovascular and oncologic. Manual segmentation of imaging data allows to obtain information on abdominal adipose tissue; however, this procedure can be cumbersome and time-consuming. On the other hand, quantitative imaging analysis based on artificial intelligence (AI) has been proposed as a fast and reliable automatic technique for segmentation of abdominal adipose tissue compartments, possibly improving the current standard of care. AI holds the potential to extract quantitative data from computed tomography (CT) and magnetic resonance (MR) images, which in most of the cases are acquired for other purposes. This information is of great importance for physicians dealing with a wide spectrum of diseases, including cardiovascular and oncologic, for the assessment of risk, pathogenesis, clinical outcomes, response to treatments, and complications. In this review we summarize the available evidence on AI algorithms aimed to the segmentation of visceral and subcutaneous adipose tissue compartments on CT and MR images.

Modification of the effects of intensive systolic blood pressure control on kidney outcomes by baseline body mass index

AIM

Obesity and intensive systolic blood pressure (SBP) control are independently associated with greater risk of acute kidney injury (AKI) and incident chronic kidney disease (CKD). We examined whether baseline body mass index (BMI) modifies the effects of intensive SBP lowering on AKI or incident CKD.

METHODS

The systolic blood pressure intervention trial (SPRINT) randomized 9361 participants with high blood pressure to an SBP target of either <120 mm Hg or < 140 mm Hg. In a secondary analysis of 9210 SPRINT participants with a baseline BMI of ≥18.5 and < 50 kg/m² , we examined the interactions of baseline BMI and SPRINT SBP intervention on subsequent AKI and incident CKD.

RESULTS

Each 5 kg/m² increase in baseline BMI was associated with higher risk of AKI (hazard ratio [HR] 1.12, 95% confidence interval [CI] 1.01 to 1.25) and incident CKD (HR 1.17, 95% CI 1.01 to 1.32). Intensive SBP control increased the risk of AKI (HR 1.68, 95% CI 1.22-2.11) and incident CKD (HR 3.49, 95% CI 2.47-4.94). The increased risk of AKI with intensive SBP control was consistent across the baseline BMI spectrum (linear interaction p = 0.55); however, the risk of incident CKD with SPRINT intervention increased with higher BMI (linear interaction p = 0.043).

CONCLUSION

The increased risk of adverse kidney events seen with intensive SBP control in the SPRINT persisted across the baseline BMI spectrum. A higher baseline BMI was associated with an augmented risk of incident CKD with intensive SBP control.

Multi-Omics Analysis to Examine Gene Expression and Metabolites From Multisite Adipose-Derived Mesenchymal Stem Cells

This study aimed at exploring the gene expression and metabolites among multisite adipose-derived mesenchymal stem cells (ASCs) and investigate the metabolic pathway using a multi-omics analysis. Subcutaneous adipose-derived mesenchymal stem cells (SASCs), perirenal adipose-derived mesenchymal stem cells (PASCs), and epididymal adipose-derived mesenchymal stem cells (EASCs) were isolated from Sprague Dawley rats. RNA and metabolites were extracted and sequenced using transcriptomics and metabolomics analyses, respectively. There were 720 differentially expressed genes (DEGs) in EASCs and 688 DEGs in PASCs compared with SASCs; there were 166 unique DEGs in EASCs, 134 unique DEGs in PASCs, and 554 common DEGs between EASCs and PASCs. Furthermore, there were 226 differential metabolites in EASCs, 255 differential metabolites in PASCs, 83 unique differential metabolites in EASCs, 112 unique differential metabolites in PASCs, and 143 common differential metabolites between EASCs and PASCs. The transcriptomics and metabolomics analyses identified four hub genes, one in EASCs and three in PASCs. There are functional differences among multisite ASCs that may be related to the hub genes Atac2, Rrm1, Rrm2, and Gla. The relevant signaling pathways are the Ras signaling pathway, HIF-1 signaling pathway, and the p53 signaling pathway. In conclusion, compared with SASCs, our multi-omics analysis identified that EASCs with higher Acat2 expression may be more correlated to fat metabolism and insulin resistance, while PASCs with abnormal expression of Rrm1/2 and Gla may be more correlated with some malignant tumors and cardiac-cerebral vascular disease.

The Factors Affecting Lower Urinary Tract Functions in Patients Undergoing Laparoscopic Sleeve Gastrectomy

BACKGROUND

We prospectively assessed changes in the lower urinary system functions of women with morbid obesity following laparoscopic sleeve gastrectomy and the factors affecting these changes.

METHODS

Data from 40 females who had undergone laparoscopic sleeve gastrectomy due to morbid obesity (body mass index, BMI ≥ 40 kg/m²) between January 2014-2016 at S.B.U. Bursa Yuksek Ihtisas Training and Research Hospital were prospectively evaluated. The presence of comorbidities, onset of obesity, smoking, American Society of Anesthesiologists (ASA) score, pre and 12-month postoperative weights and BMIs, fasting blood glucose (FBG), blood urea nitrogen, creatinine, insulin, homeostatic model assessment-insulin resistance (HOMA-IR) test results, overactive bladder survey (OAB-Q) scores, volume of urination, and Qmax values obtained from uroflowmetry studies were recorded and assessed.

RESULTS

Statistically significant differences in weight, BMI, FBG, insulin, HOMA-IR score and creatinine values pre-operation, and the corresponding values obtained at 12 months post-operation were observed (all, p < 0.001). OAB-Q scores were observed to be statistically significantly lower in the postoperative period relative to those in the preoperative period (p < 0.001). Urination volume was statistically significantly higher during the postoperative period (p = 0.048) than during the preoperative period. Non-smoking patients showed a reduction in OAB-Q score and a statistically significant increase in urination volume during the postoperative period (p < 0.001, p = 0.011, respectively); smoking patients indicated a statistically significant reduction in OAB-Q score only during the postoperative period; however, urination volume was not statistically significant between two groups (p = 0.013, p = 0.303). In patients with an ASA score of 1, preoperative OAB-Q scores were statistically significantly lower (p = 0.035) than those obtained post-operation. Patients with childhood-onset obesity showed statistically significantly increased urination volumes during postoperative period in comparison with values obtained pre-operation (p = 0.042).

CONCLUSION

Improvements in lower urinary system functions were affected by patient-related factors, such as comorbidity, obesity onset, smoking, ASA score, and weight loss, following laparoscopic sleeve gastrectomy.

Genetically driven adiposity traits increase the risk of coronary artery disease independent of blood pressure, dyslipidaemia, glycaemic traits

Adiposity has been associated with the risk of coronary artery disease (CAD) in observational studies, but their association may differ according to specific characteristics of studies. In Mendelian randomization (MR) analyses, genetic variants are used as instrumental variables (IVs) of exposures to examine causal effects to overcome confounding factors and reverse causation. We performed MR analyses for adiposity (n = 322,154) on risk of CAD (60,801 cases and 123,504 controls) based on the currently largest genome-wide association studies. The estimated associations between adiposity traits and CAD were calculated by an inverse-variance weighted method with and without excluding the IVs, which are associated with the well-known risk factors of CAD. Genetic variants are identified to be associated with the well-known risk factors of CAD by a cross-phenotype meta-analysis method. Our results furnished strong evidence for a causal role of adiposity in risk of CAD, with the odds ratios (ORs) for CAD being 1.53 (95% CI 1.36-1.72) for body mass index (BMI), 1.48 (1.20-1.96) for waist-hip ratio (WHR), and 1.34 (1.07-1.59) for WHR adjusted for BMI (WHRadjBMI), respectively. After excluding mediators-associated IVs from the MR analyses, the corresponding ORs were 1.46 (1.28-1.67) for BMI, 1.39 (1.01-1.93) for WHR, and 1.38 (1.04-1.84) for WHRadjBMI, respectively. Furthermore, our results suggested that central adiposity and general adiposity might pose a similar risk for CAD. In summary, our data supported that genetically driven adiposity traits imposed the risk of CAD independent of blood pressure, dyslipidaemia, glycaemic traits, and type 2 diabetes.

Assessing causal estimates of the association of obesity-related traits with coronary artery disease using a Mendelian randomization approach

Obesity-related traits have been associated with coronary artery disease (CAD) in observational studies, but these associations may be biased by confounding factors and reverse causation. In this study, we specifically conducted two-sample Mendelian randomization (MR) analyses to overcome these limitations and test the associations of obesity-related traits (other than body mass index (BMI)) (n = 322,154) with CAD (22,233 cases and 64,762 controls) by using summary-level data from previous studies. The methods utilized to estimate these associations included the inverse-variance weighted method, the weighted median method and MR-Egger regression. Our results supported causal effects of BMI, hip circumference (HC), waist circumference (WC), and waist-hip ratio (WHR) on CAD. The associations of BMI-adjusted HC and WC with CAD were reversed, unlike that of WHR. In MR analyses excluding overlapping single nucleotide polymorphisms (SNPs) from obesity-related traits, the associations of these traits with CAD were preserved. The associations of BMI-adjusted HC and WC with CAD require further investigation, as collider stratification may be occurring. Additionally, central adiposity (measured by WHR) separated from general adiposity (measured by BMI) and general adiposity might pose similar risks for CAD. In clinical practice, physicians should pay attention to the potential effects of different obesity-related traits on CAD.

PVAT and Its Relation to Brown, Beige, and White Adipose Tissue in Development and Function

Adipose tissue is commonly categorized into three types with distinct functions, phenotypes, and anatomical localizations. White adipose tissue (WAT) is the major energy store; the largest depots of WAT are found in subcutaneous or intravisceral sites. Brown adipose tissue (BAT) is responsible for energy dissipation during cold-exposure (i.e., non-shivering thermogenesis) and is primarily located in the interscapular region. Beige or brite (brown-in-white) adipose tissue can be found interspersed in WAT and can attain a brown-like phenotype. These three types of tissues also have endocrine functions and play major roles in whole body metabolism especially in obesity and its co-morbidities, such as cardiovascular disease. Over the last years, perivascular adipose tissue (PVAT) has emerged as an adipose organ with endocrine and paracrine functions. Pro and anti-inflammatory agents released by PVAT affect vascular health, and are implicated in the inflammatory aspects of atherosclerosis. PVAT shares several of the defining characteristics of brown adipose tissue, including its cellular morphology and expression of thermogenic genes characteristic for brown adipocytes. However, PVATs from different vessels are phenotypically different, and significant developmental differences exist between PVAT and other adipose tissues. Whether PVAT represents classical BAT, beige adipose tissue, or WAT with changing characteristics, is unclear. In this review, we summarize the current knowledge on how PVAT relates to other types of adipose tissue, both in terms of functionality, developmental origins, and its role in obesity-related cardiovascular disease and inflammation.

Association of reproductive history with hypertension and prehypertension in Chinese postmenopausal women: a population-based cross-sectional study

Hypertension and prehypertension may have important roles in the etiology of cardiovascular disease. However, the risk factors of hypertension and prehypertension have not been thoroughly elucidated to date. This study intended to explore the relative effects between reproductive history and the prevalence of hypertension and prehypertension. A population-based cross-sectional survey of postmenopausal women (n=6252), aged 41-93 years, was conducted from August 2013 to August 2015. All subjects, selected by the multistage random sampling method in Henan province, were categorized as normotension, prehypertension and hypertension according to blood pressure (BP) levels. Ordinal logistic regression models were used to estimate the risks of prehypertension and hypertension with three categories of BP as dependent variables. Hypertension was associated with a positive history of induced abortion (adjusted odds ratio (OR)=1.190, 95% confidence interval (CI): 1.020, 1.388), but there was no association between hypertension and a positive history of spontaneous abortion (adjusted OR=1.126, 95% CI: 0.973, 1.303) after adjusting for age, alcohol consumption, education status, smoking, body mass index, physical activity and occupation. Compared with women with one or no children, those with two or three children were at a lower risk of hypertension (adjusted OR=0.605, 95% CI: 0.434, 0.845). In addition, individuals with an age of menopause between 46 and 51 years may have a decreased risk of both prehypertension and hypertension, especially in terms of systolic BP. In conclusion, a positive history of induced abortion may be a predictive risk factor for hypertension and prehypertension. However, a menopausal age of 46-51 years or having two children may be protective factors against hypertension and prehypertension.

An Analysis of Anthropometric Indicators and Modifiable Lifestyle Parameters Associated with Hypertensive Nephropathy

The surge in prevalence of chronic noncommunicable diseases like hypertension and chronic kidney disease has been linked with modifiable lifestyle practices and increased body fat. This study sought to compare the association between different modifiable lifestyle practices, adiposity indices, renal function parameters, and hypertension as well as the predictive implications for levels of these parameters in target cardiac organ damage among an urban Ghanaian hypertensive population. Using a hospital-based case-control study design, 241 Ghanaian indigenes from the Kumasi metropolis were recruited for this study. The case group was made up of 180 hypertensives and 61 normotensives served as controls. In addition to sociodemographic data, standard haemodynamic, anthropometric, renal function, and cardiac organ damage assessments were done. The prevalence of chronic kidney disease (CKD) ranged from 13.3% to 16.6% depending on the equation used in estimating the glomerular filtration rate (eGFR). Percentage cluster distribution by chronic kidney disease was observed to be significantly tilted toward the upper quartiles (3rd and 4th) of the haemodynamic parameters measured. Chronic kidney disease was significantly higher among self-reported smokers and alcoholic hypertensives. In this urban population, adiposity was associated with hypertension and renal insufficiency. Chronic kidney disease was associated with hypertension and cardiac abnormalities.

Association of PPAR-γ2 and β3-AR Polymorphisms With Postmenopausal Hypertension

The aim of this study was to test the association of peroxisome proliferator-activated receptor (PPAR-γ2) (Pro12Ala, C1431T) and β3-AR (Trp64Arg) polymorphisms with metabolic, nutritional, and blood pressure parameters in 271 postmenopausal women (151 hypertensive and 120 normotensive controls). The TaqMan genotyping assay and restriction fragment length polymorphism methods were used to determine the distributions of selected alleles and genotype frequencies. Nutritional status was determined by a bioimpedance method and dietary habits were assessed via 7-day dietary recall. The distribution of selected genotypes and allele frequencies did not differ between hypertensive women and normal controls after analysis by chi-square test. The postmenopausal hypertensive women were older and had higher body fat mass, serum glucose, and triglyceride levels. The cluster analysis showed that the hypertensive group with Pro12Pro genotype had highest pulse pressure and mean arterial pressure values when compared with Pro12Ala patients. In the logistic regression analysis, blood glucose (Pro12Ala polymorphism) and energy intake (C1431Tand T1431T polymorphisms) determined hypertension.

Blood pressure control and weight loss in overweight or obese patients with previously treated or untreated mild to moderate hypertension given valsartan: An open-label study comparing pretreatment and posttreatment values

BACKGROUND

Hypertension is associated with obesity. Recent studies have indicated that therapy with an angiotensin II antagonist, in addition to having an antihypertensive effect, may cause a reduction in body weight.

OBJECTIVE

The aim of this study was to assess the efficacy and tolerability of valsartan in the treatment of overweight or obese patients with mild to moderate essential hypertension.

METHODS

Overweight or obese outpatients aged 18 to <70 years with previously treated or untreated mild to moderate essential hypertension were eligible for this open-label study conducted at the Department of Internal Medicine and Aging, Clinica Medica II, Policlinico S. Orsola-Malpighi (Bologna, Italy). After a 1-week pharmacologic washout period, patients were treated with valsartan capsules at a fixed dosage of 80 mg once daily for 8 weeks. The dosage was increased to 160 mg once daily if, at 8 weeks, diastolic blood pressure (DBP) was not normalized; otherwise, the 80-mg/d dosage was maintained. Treatment was continued for an additional 16 weeks. Patients' heart rate, systolic blood pressure (SBP) and DBP, body mass index (BMI), and waist-hip ratio (WHR) were measured/calculated at baseline (week 0) and 8, 16, and 24 weeks. Patients were asked to maintain a 1600-kcal/d diet throughout the study.

RESULTS

Forty-eight patients (28 men, 20 women; mean [SD] age, 57 [9] years) were included in the study. In the 45 patients (93.8%) who completed the study, mean SBP, DBP, and BMI were significantly decreased compared with baseline (all P < 0.001), but WHR was significantly increased (P < 0.05). After 24 weeks of treatment, 71.1 % of patients had SBP/DBP ≤ 140/≤90 mm Hg. Three patients (6.3%) withdrew from the study due to treatment-related adverse events.

CONCLUSION

In this population of overweight or obese patients with mild to moderate hypertension, valsartan was well tolerated, and could be effective in controlling blood pressure and achieving weight loss in such patients.

Factors associated with the prevalence of hypertension in the southeastern United States: insights from 69,211 blacks and whites in the Southern Community Cohort Study

BACKGROUND

Lifestyle and socioeconomic status have been implicated in the prevalence of hypertension; thus, we evaluated factors associated with hypertension in a cohort of blacks and whites with similar socioeconomic status characteristics.

METHODS AND RESULTS

We evaluated the prevalence and factors associated with self-reported hypertension (SR-HTN) and ascertained hypertension (A-HTN) among 69,211 participants in the Southern Community Cohort Study. Multivariable logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) for factors associated with hypertension. The prevalence of SR-HTN was 57% overall. Body mass index was associated with SR-HTN in all race-sex groups, with the OR rising to 4.03 (95% CI, 3.74-4.33) for morbidly obese participants (body mass index, >40 kg/m(2)). Blacks were more likely to have SR-HTN than whites (OR, 1.84; 95% CI, 1.75-1.93), and the association with black race was more pronounced among women (OR, 2.08; 95% CI, 1.95-2.21) than men (OR, 1.47; 95% CI, 1.36-1.60). Similar findings were noted in the analysis of A-HTN. Among those with SR-HTN and A-HTN who reported use of an antihypertensive agent, 94% were on at least one of the major classes of antihypertensive agents, but only 44% were on ≥2 classes and only 29% were on a diuretic. The odds of both uncontrolled hypertension (SR-HTN and A-HTN) and unreported hypertension (no SR-HTN and A-HTN) were twice as high among blacks as whites (OR, 2.13; 95% CI, 1.68-2.69; and OR, 1.99; 95% CI, 1.59-2.48, respectively).

CONCLUSIONS

Despite socioeconomic status similarities, we observed suboptimal use of antihypertensives in this cohort and racial differences in the prevalence of uncontrolled and unreported hypertension, which merit further investigation.

Oleic acid inhibits the K(ATP) channel subunit Kir6.1 and the K(ATP) current in human umbilical artery smooth muscle cells

BACKGROUND

The objective of the present study was to determine the effect of various concentrations of oleic acid (OA) on KATP channel expression and the potential relationship to exogenous nitrogen monoxide and protein kinase C levels.

METHODS

Human umbilical artery smooth muscle cells (HUASMCs), between the 7th and 10th passages, were divided into control group, OA group (final OA concentration of 0, 50, 100 or 200 μmol/L), nitric oxide (NO) intervention group, protein kinase C inhibitor group or GF-109203X (GFX) intervention group. Western immunoblotting was used to detect the protein expression of the KATP channel subunit Kir6.1. Also, quantitative real-time polymerase chain reaction analysis to determine Kir6.1 messenger RNA levels and whole-cell patch clamping to measure KATP currents were performed.

RESULTS

The results suggested that OA inhibited Kir6.1 protein and messenger RNA expression in HUASMCs. Under a high concentration of potassium (140 mmol/L), 100 μmol/L OA significantly reduced ATP-sensitive potassium current density, whereas a low extracellular concentration of potassium (5.4 mmol/L) did not influence KATP density. Pretreatment with either exogenous NO or GFX weakened the OA-induced inhibition of KATP in HUASMCs.

CONCLUSIONS

The study demonstrated that OA inhibited Kir6.1, a KATP channel subunit, in HUASMCs, and indirectly inhibited the KATP current. In addition, the results indicated that NO and/or GFX partially reversed OA inhibition in HUASMCs.

Neuroinflammatory basis of metabolic syndrome

Inflammatory reaction is a fundamental defense mechanism against threat towards normal integrity and physiology. On the other hand, chronic diseases such as obesity, type 2 diabetes, hypertension and atherosclerosis, have been causally linked to chronic, low-grade inflammation in various metabolic tissues. Recent cross-disciplinary research has led to identification of hypothalamic inflammatory changes that are triggered by overnutrition, orchestrated by hypothalamic immune system, and sustained through metabolic syndrome-associated pathophysiology. While continuing research is actively trying to underpin the identity and mechanisms of these inflammatory stimuli and actions involved in metabolic syndrome disorders and related diseases, proinflammatory IκB kinase-β (IKKβ), the downstream nuclear transcription factor NF-κB and some related molecules in the hypothalamus were discovered to be pathogenically significant. This article is to summarize recent progresses in the field of neuroendocrine research addressing the central integrative role of neuroinflammation in metabolic syndrome components ranging from obesity, glucose intolerance to cardiovascular dysfunctions.

Urogenital complications of obesity

We performed a critical review focused on the main non-oncologic disorders that have a strong, direct association with obesity: chronic kidney disease, kidney stones and female and male lower urinary tract symptoms/disorders. We discuss the epidemiology, pathogenesis and therapeutic aspects regarding the association between obesity and non-diabetic and non-hypertensive forms of chronic kidney disease directly caused or worsened by weight excess, with particular attention on obesity-related glomerulopathy (ORG), which is typical of severe obesity, and the consequences of intentional weight loss on proteinuria and glomerular filtration rate. The associations of obesity with kidney stones and lower urinary tract conditions are also discussed from the epidemiological, physiopathological and therapeutical points of view, with emphasis on the principal concerns raised by the heterogeneity of study designs and outcome definitions typical of research in these fields. We also call attention to important clinical and scientific questions that should be addressed by future research.

Impact of obesity on cardiovascular health

This review examines the impact of obesity on cardiovascular health. We will review first, relationship between obesity and hypertension. Second, we will describe obesity-related subclinical abnormalities in cardiovascular function and structure. Third, we will summarize evidence linking obesity to overt cardiovascular disease including coronary artery disease, congestive heart failure, stroke, arrhythmias and sudden cardiac death. Fourth, we will discuss the potential mechanisms underlying increased cardiovascular risk in obese subjects. Last, we will discuss contribution of sleep apnea to the link between obesity and cardiovascular disease. Despite recent progress in understanding epidemiologic and pathophysiological links between obesity and cardiovascular disease, several issues remain to be addressed in the future studies. There is a clear need to identify better markers of obesity-related subclinical cardiovascular damage. Furthermore, we should improve identification of obese subjects at highest cardiovascular risk.

The effect of obesity on chronic kidney disease

Overweightness and obesity are associated with many hemodynamic, structural, and histopathologic alterations in the kidney and with metabolic and biochemical changes that predispose to these abnormalities. Consequent to these disorders, these individuals are more likely to develop chronic kidney disease and end-stage renal failure. Overweight and obese people are more prone to develop albuminuria and, for at least some types of kidney disease, a greater amount of albuminuria and more rapid progression of renal failure. These individuals are more likely to develop diabetes mellitus and hypertension. Diabetic nephropathy, hypertensive nephrosclerosis, focal and segmental glomerulosclerosis, renal cell carcinoma, and urate and calcium oxalate urolithiasis are the more common kidney and urological diseases reported in obese people. Preliminary data indicate that many of the clinical and nephropathologic manifestations associated with obesity can be reversed or ameliorated with reductions in body fat induced by dietary energy restriction or surgical procedures that reduce intake and gastrointestinal absorption of calories.

The effect of nutrition on blood pressure

The incidence and severity of hypertension are affected by nutritional status and intake of many nutrients. Excessive energy intake and obesity are major causes of hypertension. Obesity is associated with increased activity of the renin-angiotensin-aldosterone and sympathetic nervous systems, possibly other mineralcorticoid activity, insulin resistance, salt-sensitive hypertension and excess salt intake, and reduced kidney function. High sodium chloride intake strongly predisposes to hypertension. Increased alcohol consumption may acutely elevate blood pressure. High intakes of potassium, polyunsaturated fatty acids, and protein, along with exercise and possibly vitamin D, may reduce blood pressure. Less-conclusive studies suggest that amino acids, tea, green coffee bean extract, dark chocolate, and foods high in nitrates may reduce blood pressure. Short-term studies indicate that specialized diets may prevent or ameliorate mild hypertension; most notable are the Dietary Approaches to Stop Hypertension (DASH) diet, which is high in fruits, vegetables, and low-fat dairy products, and the DASH low-sodium diet. Long-term compliance to these diets remains a major concern.

Effect of body weight loss and normalization on blood pressure in overweight non-obese patients with stage 1 hypertension

We evaluated the effects of body weight (BW) loss on blood pressure (BP) in overweight non-obese patients with stage 1 hypertension. We enrolled 376 overweight (body mass index (BMI) >or=25 and <30 kg m(-2)) stage 1 hypertensive patients in this prospective 12-month trial. Each patient received tailored, low caloric dietary advice. After 6 months, patients with a BW reduction <5% were excluded. Body weight, BMI, BP, fasting plasma glucose (FPG), fasting plasma insulin (FPI), leptin (pL), renin and aldosterone levels were evaluated at baseline and after 6 and 12 months. In 222 patients who completed the study, a mean weight reduction of 8.1 kg reduced systolic blood pressure (SBP) by 4.2 mm Hg and diastolic blood pressure (DBP) by 3.3 mm Hg (P<0.05), which was accompanied by a significant decrease in FPI, pL and aldosterone levels (P<0.05). Larger SBP/DBP reductions were observed in 106 patients with normalized BMI (-5/-4.5 mm Hg, P<0.01) compared with the 116 patients who did not become normalized (-3.3/-1.6 mm Hg). The former also presented with greater decreases in FPG, FPI, pL, renin and aldosterone levels. Of the 106 patients who had normalized BMI, 52 also had normalized BP. Clinical and metabolic characteristics of these patients were similar to those of the 56 patients who did not have normalized BP. In overweight, mild hypertensive patients, weight loss was effective in reducing BP and in reversing some endocrinologic alterations associated with being overweight. Half of the patients who had normalized BMI also had normalized BP, which could indicate that these patients essentially did not have a form of hypertension but that these effects were instead secondary to being overweight.

Subcutaneous and visceral adipose tissue: structural and functional differences

Obesity is a heterogeneous disorder. Obese individuals vary in their body fat distribution, their metabolic profile and degree of associated cardiovascular and metabolic risk. Abdominal obesity carries greater risk of developing diabetes and future cardiovascular events than peripheral or gluteofemoral obesity. There are differences between adipose tissue present in subcutaneous areas (SCAT) and visceral adipose tissue (VAT) present in the abdominal cavity. These include anatomical, cellular, molecular, physiological, clinical and prognostic differences. Anatomically, VAT is present mainly in the mesentery and omentum, and drains directly through the portal circulaion to the liver. VAT compared with SCAT is more cellular, vascular, innervated and contains a larger number of inflammatory and immune cells, lesser preadipocyte differentiating capacity and a greater percentage of large adipocytes. There are more glucocorticoid and androgen receptors in VAT than in SCAT. VAT adipocytes are more metabolically active, more sensitive to lipolysis and more insulin-resistant than SCAT adipocytes. VAT has a greater capacity to generate free fatty acids and to uptake glucose than SCAT and is more sensitive to adrenergic stimulation, while SCAT is more avid in absorption of circulating free fatty acids and triglycerides. VAT carries a greater prediction of mortality than SCAT.

Interaction of aldosterone and extracellular volume in the pathogenesis of obesity-associated kidney disease: a narrative review

Obesity and obesity-associated kidney injuries have played an important role in the rising prevalence of chronic kidney disease (CKD). The link between obesity and kidney disease begins with obesity's well-known associations with diabetes and hypertension, the two leading etiologies of CKD. However, a growing body of evidence suggests that elevated aldosterone levels and expanded extracellular volume are key components of obesity-induced renal disease via aldosterone's non-epithelial effects on the kidney. Highlighting these blood pressure- and diabetes-independent mechanisms of kidney injury in obesity allows an exploration of whether mineralocorticoid receptor blockade, coupled with weight loss and salt restriction, is an optimal treatment for overweight CKD patients.

Non-esterified fatty acids and blood pressure elevation: a mechanism for hypertension in subjects with obesity/insulin resistance?

The prevalence of hypertension in individuals with obesity or type II diabetes is substantially elevated. Increased levels of non-esterified fatty acids (NEFAs) in abdominally obese subjects were reported to contribute in the development of various disturbances related to the metabolic syndrome, such as hepatic and peripheral insulin resistance (IR), dyslipidaemia, beta-cell apoptosis, endothelial dysfunction and others. However, the involvement of NEFAs in the development of hypertension has been much less studied in comparison to other mechanisms linking IR and central obesity with blood pressure (BP) elevation. This article reviews the existing evidence on the relation between NEFA and hypertension in an attempt to shed a light on it. In vivo data from both animal and human studies support that acute plasma NEFA elevation leads to increase in BP levels, whereas epidemiological evidence suggests a link between increased NEFA levels and hypertension. Further, accumulating data indicate the existence of several pathways through which NEFAs could promote BP elevation, that is alpha(1)-adrenergic stimulation, endothelial dysfunction, increase in oxidant stress, stimulation of vascular cell's growth and others. The above data support a possible important role of NEFA in hypertension development in patients with obesity and the metabolic syndrome and raise hypotheses for future research.

The role of obesity and its bioclinical correlates in the progression of chronic kidney disease

In spite of a progressive fall in the incidence of traditional risk factors of cardiovascular morbidity (cigarette smoking, high blood pressure, and hyperlipidemia), there is an upward trend in the prevalence of obesity and chronic kidney disease (CKD). Furthermore, there is a strong correlation between body mass indices and the relative risk of progression of CKD. The close biophysiological interaction between obesity and CKD is evident by a similar occurrence of comorbidities including insulin resistance, hyperlipidermia, endothelial dysfunction, and sleep disorders. Truncal obesity is a primary component of metabolic syndrome; unlike peripheral fat, the visceral adipocytes are more resistant to insulin. In addition, lipolysis results in a release of free fatty acid and TG, whereas hypertriglycedemia is potentiated by uremic activation of fatty acid synthase. Hypertriglycedemia and low HDL cholesterol increase the relative risk of progression of CKD. Furthermore, endothelial inflammation and premature atherosclerosis are promoted by hyperhomocysteinemia and oxidation of LDL, both of which are commonly observed in CKD and obesity. Predominance of oxidative stress in both obesity and azotemia stimulate synthesis of angiotensin II, which in turn increases TGF-B and plasminogen activator inhibitor-1, thereby propagating glomerular fibrosis. Furthermore, local synthesis of angiotensinogen by adipocytes, leptin activation of sympathetic nervous system, and hyperinsulinemia contribute to the development of hypertension in obesity and CKD. In addition, increased renal tubular expression of Na-K-ATPase and a blunted response to natiuretic hormones in obesity promote salt and water retention. Glomerular hyperfiltration from systemic volume load and hypertension results in mesangial cellular proliferation and progressive renal fibrosis. In addition, maternal nutritional deprivation increases the incidence of obesity, hypertension, and diabetes in adulthood. Reduced fetal protein synthesis contributes to oxidative glomerular injury and impairment of renal morphogenesis. Thus, kidneys are poorly equipped to handle physiologic stress that may result from the rapid body growth and programmed metabolic dysfunction later in life. Finally, in order to minimize morbidity of obesity-related kidney disease, preventive strategy must include optimal maternal health care, promotion of healthy nutrition and routine physical exercise, and early detection of CKD.

Diagnosis and management of hypertension in obesity

Cardiovascular risk in a patient with obesity hypertension increases with the extent of risk factor clustering. It is therefore important to determine the global risk of a patient with hypertension rather than to focus solely on blood pressure. Every hypertensive should be screened for other than blood pressure risk factors, target organ damage and concomitant diseases or accompanying clinical conditions. Assessment of blood pressure and target organ damage might be more difficult in obese hypertensives than in normal-weight patients. Intensive lifestyle interventions can reduce weight, and decrease blood pressure and cardiovascular risk in obese hypertensive patients. Current guidelines do not provide specific recommendation for pharmacological management of the hypertensive patients with obesity. Recent trials have consistently shown that therapy involving beta-blockers and diuretics may induce more new-onset diabetes compared with other combination therapies. Several lines of evidence suggest that anti-hypertensive agents that block the renin-angiotensin system may be especially beneficial in treating obese hypertensive patients. Hypertension management in obese individuals is complicated by poorer response to treatment, and the increased need for multiple medications. It is important to consider obstructive sleep apnoea in the differential diagnosis of hypertensive patients who respond poorly to combination therapy with anti-hypertensive medications.

The role of saturation of fat depots in the pathogenesis of insulin resistance

Insulin resistance is the earliest observable abnormality in individuals who are predisposed to, and who later develop type 2 diabetes mellitus. We hypothesize that saturation of the subcutaneous fat depot is the primary event in the pathophysiology of insulin resistance in the majority of patients and postulate that this seminal event may lead to the development of hypertension, hypertriglyceridemia and depressed HDL levels (i.e., the metabolic syndrome). Our hypothesis has the following clinical implications: (1) differing responses to weight loss may be seen with regards to insulin resistance depending on the size of the fat depot; individuals with small fat depots having to maintain an extremely low body mass to preserve an insulin sensitive phenotype while individuals with a large fat depot may become insulin sensitive even when still clinically obese with some amount of weight loss; (2) peroxisome proliferator activated receptor gamma agonists, such as thiazoledinediones which expand the subcutaneous fat depot, may be especially useful in improving insulin resistance in individuals with small fat depots; (3) expanding alternate storage sites for triglycerides by a variety of techniques, such as resistance training-induced muscle hypertrophy, may also improve insulin resistance; (4) drugs, such as beta 3 adrenergic receptor agonists which promote lipolysis and have been suggested as possible agents in the treatment of obesity may actually increase insulin resistance by releasing free fatty acids into the circulation. Similarly, inhibitors of the beta oxidation of free fatty acids (e.g., carnitine palmitoyl transferase inhibitors) may also actually cause insulin resistance by sparing fat from oxidation and thus worsening fat depot saturation and (5) liposuction, by reducing the size of the subcutaneous fat depot may actually worsen insulin resistance, thus increasing the risk of type 2 diabetes mellitus.

Efficacy and safety of sibutramine in 2225 subjects with cardiovascular risk factors: short-term, open-label, observational study

This study aims to determine the efficacy and tolerability of sibutramine hydrochloride in overweight and obese patients with cardiovascular risk factors. This was a 12-week, open-label, observational trial carried out in primary care settings. Patients' data were obtained from questionnaires received from 153 physicians. A total of 2225 overweight and obese (BMI> or =27 kg/m2) patients received sibutramine in single daily doses of 10 and/or 15 mg. The study population included patients in general good health and with controlled hypertension (41.2%), type II diabetes mellitus (15.6%), hyperlipidaemia (45.5%), and who were chronic tobacco users (smokers) (37.0%). The main outcome measures were changes in body weight, blood pressure and heart rate, and evaluation of reported adverse events. Reduction of body weight of at least >5% from baseline to week 12 was achieved in 2030 (91%) patients and >10% was achieved in 987 (44%) patients. Baseline differences in the percentages of male and female patients, presence or absence of hyperlipidaemia or smoking status did not appear to affect the rate of weight change. Weight loss was less in patients with type II diabetes mellitus and/or controlled systolic hypertension at baseline compared to those patients without these conditions. Mean systolic and diastolic blood pressure and heart rate decreased from baseline to week 12. Overall, sibutramine was well tolerated. In conclusions, treatment with sibutramine resulted in clinically significant weight loss during short-term therapy in obese adults with a range of cardiovascular risk factors..

Management of hypertension in overweight and obese patients: A practical guide for clinicians

The association between obesity and cardiovascular disease is well established, and up to 60% of overweight or obese patients have hypertension. Dietary interventions associated with modest weight loss are effective in controlling blood pressure and in reducing use of antihypertensive drug therapy in overweight and obese patients. However, long-term maintenance of weight loss is achieved only in a small proportion of patients. Orlistat and sibutramine may help to achieve and maintain weight loss but may not be sufficient to control blood pressure in overweight and obese hypertensive patients. Consequently, antihypertensive drug therapy is often necessary in addition to weight loss interventions. Few studies have investigated different antihypertensive drugs, specifically in overweight and obese patients with hypertension. Based on studies involving obese and nonobese patients, first-line treatment options include a diuretic alone or an angiotensin-converting enzyme (ACE) inhibitor alone. If monotherapy is inadequate for blood pressure control, combination therapy with diuretic and ACE inhibitor and/or combining either of these drugs with a calcium channel blocker are reasonable treatment options. Additional studies to further clarify the management of these patients are warranted.

The Management of Hypertension in the Overweight and Obese Patient

The management of hypertension in the overweight and obese patient is a frequently encountered but under investigated clinical problem. The conventional management of such patients involves weight reduction with dietary therapy or a combined approach with dietary and anti-obesity drug therapy. However, long-term weight reduction, which is necessary to sustain blood pressure (BP) control, is not feasible in over 80% of patients. Anti-obesity therapy with orlistat has inconsistent effects on BP and may benefit only patients who have uncontrolled or non-medicated hypertension. Anti-obesity therapy with sibutramine may be associated with a modest worsening of BP control. Consequently, antihypertensive drug therapy is often required to supplement a weight reduction programme, and also in patients with severe hypertension or hypertension-associated end-organ damage. Treatment with a thiazide diuretic should be considered as first-line antihypertensive drug therapy in overweight and obese patients. ACE inhibitors or non-dihydropyridine calcium channel antagonists are reasonable alternatives where clinically indicated, or they can be used in combination with a thiazide diuretic if treatment with the diuretic alone is insufficient. If such treatment is inadequate for BP control, the addition or substitution of an alpha- or beta-adrenoceptor antagonist may be considered, although the latter can be associated with weight gain. Concurrent disease is an important determinant of first-line and supplementary antihypertensive drug therapy. Additional studies are needed to determine the long-term (>1 year) efficacy and safety of antihypertensive and anti-obesity management strategies in the overweight and obese hypertensive patient.

Endocrine effects of nasal continuous positive airway pressure in male patients with obstructive sleep apnoea

OBJECTIVE

Obstructive sleep apnoea (OSA) is a relatively common condition producing disabling somnolence and profound physiological responses to hypoxaemic episodes during sleep, including significant oscillations in blood pressure. This study aimed to provide controlled data on the interaction between OSA and endocrine axes to establish whether overrepresentation of pathology such as hypertension and hypogonadism in OSA subjects might have an endocrine basis.

DESIGN, SETTING AND SUBJECTS

Parallel randomized sham placebo controlled 1-month trial of nasal continuous positive airway pressure (nCPAP) in 101 male subjects with OSA presenting to a respiratory sleep clinic.

METHODS

Analysis of gonadotrophins, testosterone, sex hormone binding protein (SHBG), prolactin, cortisol, thyroid stimulating hormone (TSH), free thyroxine (free T4), insulin-like growth factor-1 (IGF-1), renin and aldosterone were performed at baseline and after 1 month's active or placebo nCPAP intervention. Quality of life questionnaire scoring was also recorded over the same time period.

RESULTS

Testosterone and SHBG showed significant negative correlations with baseline OSA severity. Active treatment of OSA produced SHBG elevation and TSH reduction (P< or =0.03). Both groups showed an increase in aldosterone (P<0.001) and IGF-1 (P< or =0.03), associated with a large improvement in subjective quality of life scoring.

CONCLUSIONS

These findings demonstrate significant changes in endocrine axes not previously reported in a placebo-controlled trial. OSA is a recognized reversible cause of testosterone reduction; SHBG suppression correlating to baseline OSA severity supports a diagnosis of secondary hypogonadism. Significant rises in aldosterone and IGF-1 on treatment coincide with increased physical activity and an improved quality of life score.

Obesity-associated activation of angiotensin and endothelin in the cardiovascular system

The renin-angiotensin system (RAS) and the endothelin system have been implicated in the pathogenesis of human cardiovascular and renal diseases, and inhibition of the RAS markedly improves morbidity and survival. Obesity in humans is associated with an increased risk for the development of hypertension, atherosclerosis and focal-segmental glomerulosclerosis, however the exact mechanisms underlying these pathologies in obese individuals are not known. This article discusses the clinical importance of obesity and the current evidence for local activation of the renin-angiotensin system and its interactions with the endothelin system in obesity and the cardiovascular pathologies associated with it.