Insulin status and vascular responses to weight loss in obesity

The association between triglyceride-glucose index and related parameters and risk of cardiovascular disease in American adults under different glucose metabolic states

BACKGROUND

Cardiovascular disease (CVD) encompasses an array of cardiac and vascular disorders, posing a significant threat to global health. It remains unclear whether there exists an association between triglyceride-glucose index (TyG) and its derived indices and the incidence of cardiovascular disease, and in particular, the strength of the association in populations with different glucose metabolisms is not known.

METHODS

Data extracted from the National Health and Nutrition Examination Survey (NHANES) covering the period from 1999 to 2020, involving a cohort of 14,545 participants, were leveraged for the analysis. Statistical assessments were executed utilizing R software, employing multivariable logistic regression models to scrutinize the correlation between TyG and its associated parameters with the incidence of cardiovascular disease across diverse glucose metabolism categories. Interaction analyses and restricted cubic splines were applied to evaluate potential heterogeneity in associations and investigate the link between TyG and its derivatives with the occurrence of cardiovascular disease. Furthermore, receiver operating characteristic curves were constructed to evaluate the extent of variability in the predictive performance of TyG and its derived parameters for cardiovascular disease across distinct glucose metabolic statuses.

RESULTS

This study found that TyG and its related parameters were differentially associated with the occurrence of cardiovascular disease in different glucose metabolic states. Curvilinear correlations were found between TyG in the IFG population and TyG-WC, TyG-BMI, and TyG-WHtR in the impaired glucose tolerance (IGT) population with the occurrence of cardiovascular disease. In addition, the introduction of TyG and its derived parameters into the classical Framingham cardiovascular risk model improved the predictive performance in different glucose metabolism populations. Among them, the introduction of TyG-WHtR in the normal glucose tolerance (NGT), impaired fasting glucose (IFG), IFG & IGT and diabetes groups and TyG in the IGT group maximized the predictive power.

CONCLUSIONS

The findings provide new insights into the relationship between the TyG index and its derived parameters in different glucose metabolic states and the risk of cardiovascular disease, offering important reference value for future clinical practice and research. The study highlights the potential for improved risk stratification and prevention strategies based on TyG and its derived parameters.

Sleeve gastrectomy improved microvascular phenotypes from obesity cohort, detected with optical coherence tomography angiography

AIMS

To examine how metabolic status is associated with microvascular phenotype and to identify variables associated with vascular remodeling after bariatric surgery, using noninvasive optical coherence tomography angiography (OCTA).

METHODS

The study included 136 obese subjects scheduled for bariatric surgery and 52 normal-weight controls. Patients with obesity were divided into metabolically healthy obesity (MHO) and metabolic syndrome (MetS) groups according to the diagnosis criteria of the Chinese Diabetes Society. Retinal microvascular parameters were measured by OCTA, including superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel densities. Follow-ups were performed at the baseline and 6 months after bariatric surgery.

RESULTS

Fovea SCP, average DCP, fovea DCP, parafovea DCP, and perifovea DCP vessel densities were significantly lower in the MetS group, compared to controls (19.91% vs. 22.49%, 51.60% vs. 54.20%, 36.64% vs. 39.14%, 56.24% vs. 57.65% and 52.59% vs. 55.58%, respectively, all p < .05). Parafovea SCP, average DCP, parafovea DCP, and perifovea DCP vessel densities significantly improved in patients with obesity 6 months after surgery, compared to baseline (54.21% vs. 52.97%, 54.43% vs. 50.95%, 58.29% vs. 55.54% and 55.76% vs. 51.82%, respectively, all p < .05). Multivariable analyses showed that baseline blood pressure and insulin were independent predictors of vessel density changes 6 months after surgery.

CONCLUSIONS

Retinal microvascular impairment occurred mainly in MetS rather than MHO patients. Retinal microvascular phenotype improved 6 months after bariatric surgery and baseline blood pressure and insulin status may be key determinants. OCTA may be a reliable method to evaluate the microvascular complications associated with obesity.

Insulin Resistance-Varying Associations of Adiposity Indices with Cerebral Perfusion in Older Adults: A Population-Based Study

OBJECTIVES

Excessive accumulation of adipose tissue may accelerate brain aging, but the underlying mechanisms are poorly understood. Several adiposity indices were proposed to assess obesity, while their linkage with brain health in older adults remained unclear. Here we aimed to examine the associations of adiposity indices with global and regional cerebral blood flow (CBF) in older adults, while considering insulin resistance.

DESIGN

This was a cross-sectional population-based study that included older adults derived from the baseline participants in the ongoing Multimodal Interventions to Delay Dementia and Disability in rural China (MIND-China) study.

SETTING AND PARTICIPANTS

The study included 103 Chinese rural-dwelling older adults (age≥60 years; 69.9% women) who underwent brain magnetic resonance imaging scans.

METHODS

We estimated eight adiposity indices based on anthropometric measures. We automatically quantified global and regional CBF using the arterial spin labeling scans. Insulin resistance was assessed using the triglyceride-glucose index and then dichotomized into high and low levels according to the median. Data were analyzed using general linear model and voxel-wise analysis.

RESULTS

Of the eight examined adiposity indices, only higher waist-to-height ratio (WHtR) and body roundness index (BRI) were associated with reduced global CBF (multivariable-adjusted β-coefficients and 95%CI: -1.76; -3.25, -0.27 and -1.77; -3.25, -0.30, respectively) and hypoperfusion in bilateral middle temporal gyri, angular gyri and superior temporal gyri, left middle cingulum and precuneus (P<0.05). There were statistical interactions of WHtR and BRI with levels of insulin resistance on CBF, such that the significant associations of higher WHtR and BRI with lower global and regional CBF existed only in people with high insulin resistance (P<0.05).

CONCLUSION

Higher WHtR and BRI are associated with cerebral hypoperfusion in older adults, especially in people with high insulin resistance. This may highlight the pathological role of visceral fat in vascular brain aging.

Acute effects of singing on cardiovascular biomarkers

Background

Singing is a physical activity involving components of the vagal nerves manifested as changes in cardiac autonomic regulation.

Aims

The aim of this pilot study is to investigate the acute effects of singing on biomarkers of cardiovascular health.

Methods

Adult subjects were recruited from cardiology clinics to participate in a single 90-min study visit. Vascular function was measured at the fingertips with peripheral arterial tonometry (PAT) before and after singing to a 14-min video led by a voice expert. Heart rate variability (HRV) was measured with a chest strap sensor at baseline, during, and after singing. PAT measurements were expressed as reactive hyperemia index (RHI) and Framingham reactive hyperemia index (fRHI). Measures of HRV included root mean square of successive RR interval differences (RMSSD) and standard deviation of NN (or RR) intervals (SDNN).

Results

Sixty subjects completed the study (68% female, mean age 61 ±13 years, mean BMI 32 ± 8). There was a significant increase in fRHI (1.88 ± 0.14 to 2.10 ± 0.14, p = 0.02) after singing with no significant change in the RHI (1.99 ± 0.10 to 2.12 ± 0.09, p = 0.22). There was a reduction in HRV during singing (compared to baseline) (RMSSD: 42.0 ± 5 to 32.6 ± 4, p = 0.004 and SDNN: 54 ± 4 to 33.5 ± 3, p = 0.009). HRV measures trended back toward baseline after singing.

Conclusions

A short duration of singing improved vascular function acutely. Improvements were more substantial in subjects with abnormal baseline endothelial function. HRV patterns were similar to that of light-intensity exercise. Future studies should confirm favorable vascular adaptation to more sustained singing interventions.

Clinical trial registration

ClinicalTrials.gov, identifer: NCT03805529.

Benefits of weight loss of 10% or more in patients with overweight or obesity: A review

OBJECTIVE

Modest weight loss (5%-10%) is clinically meaningful in patients with overweight or obesity. However, greater weight loss may be required to achieve improvements in or remission of certain weight-related complications. Therefore, this study reviewed the effect of large weight loss (≥10%). Most studies reporting large weight loss and relevant outcomes used bariatric surgery or lifestyle modifications.

RESULTS

Benefits of large weight loss were observed in patients with various overweight- or obesity-related complications, including improvements in comorbidities such as type 2 diabetes and hypertension. Improvements in glucose metabolism and cardiovascular risk factors were observed in patients who achieved large weight loss through lifestyle interventions or pharmacotherapy (phentermine/topiramate 15/92 mg once daily or subcutaneous semaglutide 2.4 mg once weekly). Other benefits associated with large weight loss included reduced cancer risk and improvements in knee osteoarthritis, sleep apnea, fertility-related end points, and health-related quality of life. While costly, bariatric surgery is currently the most cost-effective intervention, although most weight-management programs are deemed cost-effective.

CONCLUSIONS

Overall, large weight loss has a major beneficial impact on overweight- and obesity-related complications. Large weight loss should be the main treatment target when modest weight loss has had insufficient effects on obesity-related complications and for patients with severe obesity.

Association of Bariatric Surgery With Vascular Outcomes

IMPORTANCE

Bariatric surgical weight loss is associated with reduced cardiovascular mortality; however, the mechanisms underlying this association are incompletely understood.

OBJECTIVES

To identify variables associated with vascular remodeling after bariatric surgery and to examine how sex, race, and metabolic status are associated with microvascular and macrovascular outcomes.

DESIGN, SETTING, AND PARTICIPANTS

This population-based longitudinal cohort included 307 individuals who underwent bariatric surgery. Participants were enrolled in the bariatric weight loss program at Boston Medical Center, a large, multi-ethnic urban hospital, with presurgical and postsurgical assessments. Data were collected from December 11, 2001 to August 27, 2019. Data were analyzed in September 2019.

EXPOSURE

Bariatric surgery.

MAIN OUTCOMES AND MEASURES

Flow-mediated dilation (FMD) and reactive hyperemia (RH) (as measures of macrovascular and microvascular function, respectively) and clinical variables were measured preoperatively at baseline and at least once postoperatively within 12 months of the bariatric intervention.

RESULTS

A total of 307 participants with obesity (mean [SD] age, 42 [12] years; 246 [80%] women; 199 [65%] White; mean [SD] body mass index, 46 [8]) were enrolled in this study. Bariatric surgery was associated with significant weight loss and improved macrovascular and microvascular function across subgroups of sex, race, and traditional metabolic syndrome (mean [SD] pre- vs postsurgery weight: 126 [25] kg vs 104 [25] kg; P < .001; mean [SD] pre- vs postsurgery FMD: 9.1% [5.3] vs 10.2% [5.1]; P < .001; mean [SD] pre- vs postsurgery RH: 764% [400] vs 923% [412]; P < .001). Factors associated with change in vascular phenotype correlated most strongly with adiposity markers and several metabolic variables depending on vascular territory (eg, association of weight change with change in RH: estimate, -3.2; 95% CI, -4.7 to -1.8; association of hemoglobin A1c with change in FMD: estimate, -0.5; 95% CI, -0.95 to -0.05). While changes in macrovascular function among individuals with metabolically healthy obesity were not observed, the addition of biomarker assessment using high-sensitivity C-reactive protein plasma levels greater than 2 mg/dL identified participants with seemingly metabolically healthy obesity who had low-grade inflammation and achieved microvascular benefit from weight loss surgery.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that bariatric intervention is associated with weight loss and favorable remodeling of the vasculature among a wide range of individuals with cardiovascular risk. Moreover, differences in arterial responses to weight loss surgery by metabolic status were identified, underscoring heterogeneity in physiological responses to adiposity change and potential activation of distinct pathological pathways in clinical subgroups. As such, individuals with metabolically healthy obesity represent a mixed population that may benefit from more refined phenotypic classification.

Insulin Resistance in Association with Thyroid Function, Psychoemotional State, and Cardiovascular Risk Factors

Background: Individuals with insulin resistance (IR) have a high risk of diabetes or metabolic syndrome, and they are more likely to have depression. Furthermore, IR by itself is a major cardiovascular risk factor in healthy persons. Thus, we aimed to investigate IR in association with thyroid function, psychoemotional state, and cardiovascular risk factors among 45–84-year-old citizens of Palanga. Methods: A randomized epidemiological study was performed with 850 subjects. All participants were evaluated for sociodemographic, clinical, and cardiovascular risk factors and biochemical analysis. IR was evaluated by the homeostasis model assessment of IR (HOMA-IR). Results: All study participants were stratified into groups without IR (HOMA-IR ≤ 2.7) and with IR (HOMA-IR > 2.7). The analysis of parameters between the two study groups showed some statistically significant relationships between IR and cardiovascular risk factors. The predictable accuracy was presented using receiver performance characteristic curves for HOMA-IR scores in women and men separately. If the HOMA-IR score is higher than 3.45, individuals are significantly more likely to have type 2 diabetes mellitus (T2DM). Conclusions: An increase of fasting glucose and more frequent incidence of metabolic syndrome, diabetes, and cardiovascular diseases in subjects with IR are associated with the prevalence of cardiovascular risk factors. There was no significant association between thyroid function and HOMA-IR. HOMA-IR cut-offs could predict the presence of T2DM.

Pyridoxamine and Caloric Restriction Improve Metabolic and Microcirculatory Abnormalities in Rats with Non-Alcoholic Fatty Liver Disease

INTRODUCTION

This study aims to examine the effect of a diet intervention and pyridoxamine (PM) supplementation on hepatic microcirculatory and metabolic dysfunction in nonalcoholic fatty liver disease (NAFLD).

METHODS

NAFLD in Wistar rats was induced with a high-fat diet for 20 weeks (NAFLD 20 weeks), and control animals were fed with a standard diet. The NAFLD diet intervention group received the control diet between weeks 12 and 20 (NAFLD 12 weeks), while the NAFLD 12 weeks + PM group also received PM. Fasting blood glucose (FBG) levels, body weight (BW), visceral adipose tissue (VAT), and hepatic microvascular blood flow (HMBF) were evaluated at the end of the protocol.

RESULTS

The NAFLD group exhibited a significant increase in BW and VAT, which was prevented by the diet intervention, irrespective of PM treatment. The FBG was elevated in the NAFLD group, and caloric restriction improved this parameter, although additional improvement was achieved by PM. The NAFLD group displayed a 31% decrease in HMBF, which was partially prevented by caloric restriction and completely prevented when PM was added. HMBF was negatively correlated to BW, FBG, and VAT content.

CONCLUSION

PM supplementation in association with lifestyle modifications could be an effective intervention for metabolic and hepatic vascular complications.

Fasting Plasma Glucose and Coronary Heart Disease in a Rural Population of North Henan, China

Even in individuals without diabetes, the incidence of coronary heart disease (CHD) increases with the rise in fasting plasma glucose (FPG); however, the threshold of FPG for CHD in rural areas of China is unclear. We retrospectively examined 2,987 people. Coronary angiography records were used to determine the presence of CHD as well as its severity. Risk factors for CHD and the relationship between different levels of FPG and CHD were analyzed. After adjusting for age, hypertension, dyslipidemia, smoking, drinking, chronic kidney disease, and previous ischemic stroke, the incidence of CHD in nondiabetic women began to increase when FPG exceeded 5.2 mmol/L (odds ratio (OR) = 1.438, 95% confidence interval (CI) = 1.099–1.880, p=0.008), and the degree of coronary artery lesions also became more severe (OR = 1.406, 95% CI = 1.107–1.788, p=0.005). However, no such correlations were found in nondiabetic men. In conclusion, among the nondiabetic women in rural areas of northern Henan, both the incidence of CHD and the severity of lesions increased when FPG levels were greater than 5.2 mmol/L, while no significant correlation between FPG and CHD was observed in diabetes-free men.

cGMP manipulation in cardiometabolic disease: chances and challenges

PURPOSE OF REVIEW

Cardiovascular and metabolic diseases are closely linked and commonly occur in the same patients. This review focuses on the cyclic guanosine monophosphate (cGMP) system and its crosstalk between metabolism and the cardiovascular system.

RECENT FINDINGS

Recent studies suggest that cGMP, which serves as second messenger for nitric oxide and for natriuretic peptides, improves oxidative metabolism and insulin signaling. The clinical evidence is particularly strong for the natriuretic peptide branch of the cGMP system. Clinical trials suggested improvements in insulin sensitivity and reductions in the risk of progressing to type 2 diabetes mellitus. However, further studies are needed.

SUMMARY

Enhancing cGMP signaling through nonpharmacological or pharmacological means may improve glucose metabolism in addition to affecting the cardiovascular system. However, excessive cGMP production could have significant unwanted cardiovascular and metabolic effects.

Post-occlusive reactive hyperemic response of skin microcirculation among extremely obese patients in the short and long term after bariatric surgery

OBJECTIVE

To assess changes of post-occlusive reactive hyperemic response in skin microcirculation among extremely obese patients 10 days and 6 months after bariatric surgery for patients with and without hypertension.

METHODS

Skin blood flow was measured using PeriFlux laser Doppler fluxmetry. Data were analyzed in the entire group and two subgroups: with and without hypertension.

RESULTS

Data from 88 patients (mean age 42.1 ± 11.2 years, 40.5% men) were analyzed. Six months after bariatric surgery, the time to reach peak flows had been shortened (2.4 ± 1.7 vs 2.1 ± 1.0 seconds, P < .05) and the area of hyperemia had increased (1027 ± 791 vs 1386 ± 699 AU*s, P < .05). The total power of post-occlusive reactive hyperemic after occlusion had been augmented mainly with power intensification of endothelial and myogenic origin. Post-occlusive reactive hyperemic parameters had changed mainly in the subgroup with hypertension. Variations of anthropometric parameters, metabolic characteristic, and adipokines mainly influenced on studied hyperemic flow parameters variations after the intervention in multiple regression analysis.

CONCLUSION

Cutaneous post-occlusive reactive hyperemic reactivity in time and frequency domains improved 6 months after bariatric surgery, and improvements in microvascular function were observed mainly in patients with hypertension. Variations of anthropometric parameters, metabolic characteristics, and adipokines had influence on hyperemic flow reactivity.

Microcirculatory Improvement Induced by Laparoscopic Sleeve Gastrectomy Is Related to Insulin Sensitivity Retrieval

AIMS

Microvascular dysfunction is a potential factor explaining the association of obesity, insulin resistance, and vascular damage in morbidly obese subjects. The purpose of the study was to evaluate possible determinants of microcirculatory improvement 1 year after laparoscopic sleeve gastrectomy (LSG) intervention.

METHODS

Thirty-seven morbidly obese subjects eligible for bariatric surgery were included in the study. Post-occlusive reactive hyperemia (PORH) of the forearm skin was measured as area of hyperemia (AH) by laser-Doppler flowmetry before LSG and after a 1-year follow-up.

RESULTS

After intervention, we observed a significant reduction in BMI, HOMA index, HbA1c, and a significant increase of AH in all patients after surgery; this variation was significant only in those patients having insulin resistance or prediabetes/diabetes. Although significant correlation between the increase of AH and the reduction of both BMI, HOMA index, and HbA1c was observed, BMI was the only independent predictor of AH variation after LSG at the linear regression analysis.

CONCLUSIONS

Our study shows that LSG intervention is correlated with a significant improvement in the microvascular function of morbidly obese subjects; this improvement seems to be related to the baseline degree of insulin-resistance and to the retrieval of insulin-sensitivity post-intervention.

Oxidative modifications of mitochondrial complex II are associated with insulin resistance of visceral fat in obesity

Obesity, particularly visceral adiposity, has been linked to mitochondrial dysfunction and increased oxidative stress, which have been suggested as mechanisms of insulin resistance. The mechanism(s) behind this remains incompletely understood. In this study, we hypothesized that mitochondrial complex II dysfunction plays a role in impaired insulin sensitivity in visceral adipose tissue of subjects with obesity. We obtained subcutaneous and visceral adipose tissue biopsies from 43 subjects with obesity (body mass index ≥ 30 kg/m²) during planned bariatric surgery. Compared with subcutaneous adipose tissue, visceral adipose tissue exhibited decreased complex II activity, which was restored with the reducing agent dithiothreitol (5 mM) ( P < 0.01). A biotin switch assay identified that cysteine oxidative posttranslational modifications (OPTM) in complex II subunit A (succinate dehydrogenase A) were increased in visceral vs. subcutaneous fat ( P < 0.05). Insulin treatment (100 nM) stimulated complex II activity in subcutaneous fat ( P < 0.05). In contrast, insulin treatment of visceral fat led to a decrease in complex II activity ( P < 0.01), which was restored with addition of the mitochondria-specific oxidant scavenger mito-TEMPO (10 µM). In a cohort of 10 subjects with severe obesity, surgical weight loss decreased OPTM and restored complex II activity, exclusively in the visceral depot. Mitochondrial complex II may be an unrecognized and novel mediator of insulin resistance associated with visceral adiposity. The activity of complex II is improved by weight loss, which may contribute to metabolic improvements associated with bariatric surgery.

Pathophysiology and Potential Non-Pharmacologic Treatments of Obesity or Kidney Disease Associated Refractory Hypertension

PURPOSE OF REVIEW

The review assesses the role of non-pharmacologic therapy for obesity and chronic kidney disease (CKD) associated refractory hypertension (rf HTN).

RECENT FINDINGS

Hypertensive patients with markedly heightened sympathetic nervous system (SNS) activity are prone to develop refractory hypertension (rfHTN). Patients with obesity and chronic kidney disease (CKD)-associated HTN have particularly heightened SNS activity and are at high risk of rfHTN. The role of bariatric surgery is increasingly recognized in treatment of obesity. Current evidence advocates for a greater role of bariatric surgery in the management of obesity-associated HTN. In contrast, renal denervation does not appear have a role in the management of obesity or CKD-associated HTN. The role of baroreflex activation as adjunctive anti-hypertensive therapy remains to be defined.

Sleeve Gastrectomy Efficacy on Metabolic and Cardiovascular Dysfunction With a Focus on the Role of Comorbidities

We evaluated the effects of sleeve gastrectomy (SG) on metabolic/cardiovascular parameters according to weight loss, visceral fat area (VFA), and homeostasis model assessment (HOMA)-insulin resistance index; we also assessed the influence of SG on comorbidities (diabetes/hypertension). At baseline and 10 to 12 months after SG, we assessed anthropometric and biochemical parameters, bioimpedentiometry, ultrasonographic VFA, liver steatosis, flow-mediated dilation, and echocardiography in 110 patients with obesity. We found that 23 (21%) patients had diabetes. Diabetic patients who normalized their glycated hemoglobin A_1C (HbA_1C) level experienced greater total weight loss (TWL), and the probability of normalizing HbA_1C levels directly correlated with TWL. Diabetic patients experienced a greater improvement in systolic blood pressure, VFA, and high-density lipoprotein cholesterol than nondiabetics, while patients with hypertension experienced a greater improvement in VFA, triglycerides, HOMA, and HbA_1C than nonhypertensive patients. The most important determinant of glucose control in diabetic patients was weight loss. Patients with diabetes and hypertension experienced a greater improvement in vascular and metabolic status after SG.

WNT5A regulates adipose tissue angiogenesis via antiangiogenic VEGF-A165b in obese humans

Experimental studies have suggested that Wingless-related integration site 5A (WNT5A) is a proinflammatory secreted protein that is associated with metabolic dysfunction in obesity. Impaired angiogenesis in fat depots has been implicated in the development of adipose tissue capillary rarefaction, hypoxia, inflammation, and metabolic dysfunction. We have recently demonstrated that impaired adipose tissue angiogenesis is associated with overexpression of antiangiogenic factor VEGF-A165b in human fat and the systemic circulation. In the present study, we postulated that upregulation of WNT5A is associated with angiogenic dysfunction and examined its role in regulating VEGF-A165b expression in human obesity. We biopsied subcutaneous and visceral adipose tissue from 38 obese individuals (body mass index: 44 ± 7 kg/m2, age: 37 ± 11 yr) during planned bariatric surgery and characterized depot-specific protein expression of VEGF-A165b and WNT5A using Western blot analysis. In both subcutaneous and visceral fat, VEGF-A165b expression correlated strongly with WNT5A protein (r = 0.9, P < 0.001). In subcutaneous adipose tissue where angiogenic capacity is greater than in the visceral depot, exogenous human recombinant WNT5A increased VEGF-A165b expression in both whole adipose tissue and isolated vascular endothelial cell fractions (P < 0.01 and P < 0.05, respectively). This was associated with markedly blunted angiogenic capillary sprout formation in human fat pad explants. Moreover, recombinant WNT5A increased secretion of soluble fms-like tyrosine kinase-1, a negative regulator of angiogenesis, in the sprout media (P < 0.01). Both VEGF-A165b-neutralizing antibody and secreted frizzled-related protein 5, which acts as a decoy receptor for WNT5A, significantly improved capillary sprout formation and reduced soluble fms-like tyrosine kinase-1 production (P < 0.05). We demonstrated a significant regulatory nexus between WNT5A and antiangiogenic VEGF-A165b in the adipose tissue of obese subjects that was linked to angiogenic dysfunction. Elevated WNT5A expression in obesity may function as a negative regulator of angiogenesis.NEW & NOTEWORTHY Wingless-related integration site 5a (WNT5A) negatively regulates adipose tissue angiogenesis via VEGF-A165b in human obesity.

Relations of Metabolically Healthy and Unhealthy Obesity to Digital Vascular Function in Three Community-Based Cohorts: A Meta-Analysis

Background

Microvascular dysfunction is a marker of early vascular disease that predicts cardiovascular events. Whether metabolically healthy obese individuals have impaired microvascular function remains unclear. The aim of this study was to evaluate the relation of obesity phenotypes stratified by metabolic status to microvascular function.

Methods and Results

We meta‐analyzed aggregate data from 3 large cohorts (Brazilian Longitudinal Study of Adult Health, the Framingham Heart Study, and the Gutenberg Heart Study; n=16 830 participants, age range 19–90, 51.3% men). Regression slopes between cardiovascular risk factors and microvascular function, measured by peripheral arterial tonometry (PAT), were calculated. Individuals were classified as normal‐weight, overweight, or obese by body mass index (BMI) and stratified by healthy or unhealthy metabolic status based on metabolic syndrome using the ATP‐III criteria. Male sex, BMI, and metabolic risk factors were associated with higher baseline pulse amplitude and lower PAT ratio. There was stepwise impairment of vascular measures from normal weight to obesity in both metabolic status strata. Metabolically healthy obese individuals had more impaired vascular function than metabolically healthy normal‐weight individuals (baseline pulse amplitude 6.12±0.02 versus 5.61±0.01; PAT ratio 0.58±0.01 versus 0.76±0.01, all P<0.0001). Metabolically unhealthy obese individuals had more impaired vascular function than metabolically healthy obese individuals (baseline pulse amplitude 6.28±0.01 versus 6.12±0.02; PAT ratio 0.49±0.01 versus 0.58±0.01, all P<0.0001).

Conclusions

Metabolically healthy obese individuals have impaired microvascular function, though the degree of impairment is less marked than in metabolically unhealthy obese individuals. Our findings suggest that obesity is detrimental to vascular health irrespective of metabolic status.

Comparable Attenuation of Sympathetic Nervous System Activity in Obese Subjects with Normal Glucose Tolerance, Impaired Glucose Tolerance, and Treatment Naïve Type 2 Diabetes following Equivalent Weight Loss

Background and Purpose: Elevated sympathetic nervous system (SNS) activity is a characteristic of obesity and type 2 diabetes (T2D) that contributes to target organ damage and cardiovascular risk. In this study we examined whether baseline metabolic status influences the degree of sympathoinhibition attained following equivalent dietary weight loss.

Methods: Un-medicated obese individuals categorized as normal glucose tolerant (NGT, n = 15), impaired glucose tolerant (IGT, n = 24), and newly-diagnosed T2D (n = 15) consumed a hypocaloric diet (29% fat, 23% protein, 45% carbohydrate) for 4-months. The three groups were matched for baseline age (56 ± 1 years), body mass index (BMI, 32.9 ± 0.7 kg/m²), and gender. Clinical measurements included whole-body norepinephrine kinetics, muscle sympathetic nerve activity (MSNA, by microneurography), spontaneous cardiac baroreflex sensitivity (BRS), and oral glucose tolerance test.

Results: Weight loss averaged −7.5 ± 0.8, −8.1 ± 0.5, and −8.0 ± 0.9% of body weight in NGT, IGT, and T2D groups, respectively. T2D subjects had significantly greater reductions in fasting glucose, 2-h glucose and glucose area under the curve (AUC₀₋₁₂₀) compared to NGT and IGT (group effect, P <0.001). Insulinogenic index decreased in IGT and NGT groups and increased in T2D (group × time, P = 0.04). The magnitude of reduction in MSNA (−7 ± 3, −8 ± 4, −15 ± 4 burst/100 hb, respectively) and whole-body norepinephrine spillover rate (−28 ± 8, −18 ± 6, and −25 ± 7%, respectively), time effect both P <0.001, did not differ between groups. After adjustment for age and change in body weight, Δ insulin AUC₀₋₁₂₀ was independently associated with reduction in arterial norepinephrine concentration, whilst Δ LDL-cholesterol and improvement in BRS were independently associated with decrease in MSNA.

Conclusions: Equivalent weight loss through hypocaloric diet is accompanied by similar sympathoinhibition in matched obese subjects with different baseline glucose tolerance. Attenuation of hyperinsulinemia and hyperlipidemia, rather than glycemic indices, is associated with reduction in SNS activity following weight loss intervention.

WNT5A-JNK regulation of vascular insulin resistance in human obesity

Obesity is associated with the development of vascular insulin resistance; however, pathophysiological mechanisms are poorly understood. We sought to investigate the role of WNT5A-JNK in the regulation of insulin-mediated vasodilator responses in human adipose tissue arterioles prone to endothelial dysfunction. In 43 severely obese (BMI 44±11 kg/m²) and five metabolically normal non-obese (BMI 26±2 kg/m²) subjects, we isolated arterioles from subcutaneous and visceral fat during planned surgeries. Using videomicroscopy, we examined insulin-mediated, endothelium-dependent vasodilator responses and characterized adipose tissue gene and protein expression using real-time polymerase chain reaction and Western blot analyses. Immunofluorescence was used to quantify endothelial nitric oxide synthase (eNOS) phosphorylation. Insulin-mediated vasodilation was markedly impaired in visceral compared to subcutaneous vessels from obese subjects (p<0.001), but preserved in non-obese individuals. Visceral adiposity was associated with increased JNK activation and elevated expression of WNT5A and its non-canonical receptors, which correlated negatively with insulin signaling. Pharmacological JNK antagonism with SP600125 markedly improved insulin-mediated vasodilation by sixfold (p<0.001), while endothelial cells exposed to recombinant WNT5A developed insulin resistance and impaired eNOS phosphorylation (p<0.05). We observed profound vascular insulin resistance in the visceral adipose tissue arterioles of obese subjects that was associated with up-regulated WNT5A-JNK signaling and impaired endothelial eNOS activation. Pharmacological JNK antagonism markedly improved vascular endothelial function, and may represent a potential therapeutic target in obesity-related vascular disease.

Effect of Bariatric Weight Loss on the Adipose Lipolytic Transcriptome in Obese Humans

Background. Dysregulated lipolysis has been implicated in mechanisms of cardiometabolic disease and inflammation in obesity. Purpose. We sought to examine the effect of bariatric weight loss on adipose tissue lipolytic gene expression and their relationship to systemic metabolic parameters in obese subjects. Methods/Results. We biopsied subcutaneous adipose tissue in 19 obese individuals (BMI 42 ± 5 kg/m², 79% female) at baseline and after a mean period of 8 ± 5 months (range 3–15 months) following bariatric surgery. We performed adipose tissue mRNA expression of proteins involved in triglyceride hydrolysis and correlated their weight loss induced alterations with systemic parameters associated with cardiovascular disease risk. mRNA transcripts of adipose triglyceride lipase (ATGL), hormone-sensitive lipase (HSL), and lipid droplet proteins comparative gene identification 58 (CGI-58) and perilipin increased significantly after weight loss (p < 0.05 for all). ATGL expression correlated inversely with plasma triglyceride (TG), hemoglobin A1C (HbA1C), and glucose, and HSL expression correlated negatively with glucose, while CGI-58 was inversely associated with HbA1C. Conclusion. We observed increased expression of adipose tissue lipolytic genes following bariatric weight loss which correlated inversely with systemic markers of lipid and glucose metabolism. Functional alterations in lipolysis in human adipose tissue may play a role in shaping cardiometabolic phenotypes in human obesity.

Visceral adiposopathy: a vascular perspective

Obesity has emerged as one of the most critical health care problems globally that is associated with the development of insulin resistance, type 2 diabetes mellitus, metabolic dysfunction and cardiovascular disease. Central adiposity with intra-abdominal deposition of visceral fat, in particular, has been closely linked to cardiometabolic consequences of obesity. Increasing epidemiological, clinical and experimental data suggest that both adipose tissue quantity and perturbations in its quality termed "adiposopathy" contribute to mechanisms of cardiometabolic disease. The current review discusses regional differences in adipose tissue characteristics and highlights profound abnormalities in vascular endothelial function and angiogenesis that are manifest within the visceral adipose tissue milieu of obese individuals. Clinical data demonstrate up-regulation of pro-inflammatory and pro-atherosclerotic mediators in dysfunctional adipose tissue that may support pathological vascular changes not only locally in fat but also in multiple organ systems, including coronary and peripheral circulations, potentially contributing to mechanisms of obesity-related cardiovascular disease.

Reduction in peripheral vascular resistance predicts improvement in insulin clearance following weight loss

Background

The hyperinsulinemia of obesity is a function of both increased pancreatic insulin secretion and decreased insulin clearance, and contributes to cardiovascular risk. Whilst weight loss is known to enhance insulin clearance, there is a paucity of data concerning the underlying mechanisms. This study was conducted to examine the inter-relationships between changes in sympathetic nervous system (SNS) activity, vascular function and insulin clearance during a weight loss program.

Methods

Seventeen non-smoking, un-medicated individuals aged 55 ± 1 years (mean ± SEM), body mass index (BMI) 33.9 ± 1.7 kg/m², underwent a 4-month hypocaloric diet (HCD), using a modified Dietary Approaches to Stop Hypertension diet, whilst seventeen age- and BMI-matched subjects acted as controls. Insulin sensitivity and insulin clearance were assessed via euglycemic hyperinsulinemic clamp (exogenous insulin clearance); hepatic insulin extraction was calculated as fasting C-peptide to insulin ratio (endogenous insulin clearance); SNS activity was quantified by microneurographic nerve recordings of muscle sympathetic nerve activity (MSNA) and whole-body norepinephrine kinetics; and vascular function by calf venous occlusion plethysmography and finger arterial tonometry.

Results

Weight loss averaged −8.3 ± 0.6 % of body weight in the HCD group and was accompanied by increased clamp-derived glucose utilization (by 20 ± 9 %, P = 0.04) and exogenous insulin clearance (by 12 ± 5 %, P = 0.02). Hepatic insulin extraction increased from 6.3 ± 0.8 to 7.1 ± 0.9 (P = 0.09). Arterial norepinephrine concentration decreased by −12 ± 5 %, whole-body norepinephrine spillover rate by −14 ± 8 %, and MSNA by −9 ± 5 bursts per 100 heartbeats in the HCD group (P all >0.05 versus control group). Step-wise regression analysis revealed a bidirectional relationship between enhanced exogenous insulin clearance post weight loss and reduction in calf vascular resistance (r = −0.63, P = 0.01) which explained 40 % of the variance. Increase in hepatic insulin extraction was predicted by enhanced finger reactive hyperaemic response (P = 0.006) and improvement in oral glucose tolerance (P = 0.002) which together explained 64 % of the variance.

Conclusions

Insulin clearance is independently and reciprocally associated with changes in vascular function during weight loss intervention.

Trial registration ClinicalTrials.gov: NCT01771042 and NCT00408850

Lipidomic profiling at the interface of metabolic surgery and cardiovascular disease

Bariatric surgery has helped patients attain not only significant and sustained weight loss but has also proved to be an effective means of mitigating or reversing various obesity-related comorbidities. The impressive rates of remission or resolution of type 2 diabetes mellitus (T2D) following bariatric surgery are well documented and have rightly received great attention. Less understood are the effects of bariatric surgery on cardiovascular disease (CVD) and its underlying risk factors. Thanks to the availability of increasingly sensitive laboratory tools, the emerging science of lipidomics and metagenomics is poised to offer significant contributions to our understanding of metabolically induced vascular diseases. They are set to identify novel mechanisms explaining how the varied approaches of bariatric surgery produce the remarkable improvements in multiple organs observed during patient follow-up. This article reviews recent and novel findings in patients through the lens of lipidomics with an emphasis on CVD.

Forkhead box O-1 modulation improves endothelial insulin resistance in human obesity

OBJECTIVE

Increased visceral adiposity has been closely linked to insulin resistance, endothelial dysfunction, and cardiometabolic disease in obesity, but pathophysiological mechanisms are poorly understood. We sought to investigate mechanisms of vascular insulin resistance by characterizing depot-specific insulin responses and gain evidence that altered functionality of transcription factor forkhead box O-1 (FOXO-1) may play an important role in obesity-related endothelial dysfunction.

APPROACH AND RESULTS

We intraoperatively collected paired subcutaneous and visceral adipose tissue samples from 56 severely obese (body mass index, 43 ± 7 kg/m(2)) and 14 nonobese subjects during planned surgical operations, and characterized depot-specific insulin-mediated responses using Western blot and quantitative immunofluorescence techniques. Insulin signaling via phosphorylation of FOXO-1 and consequent endothelial nitric oxide synthase stimulation was selectively impaired in the visceral compared with subcutaneous adipose tissue and endothelial cells of obese subjects. In contrast, tissue actions of insulin were preserved in nonobese individuals. Pharmacological antagonism with AS1842856 and biological silencing using small interfering RNA-mediated FOXO-1 knockdown reversed insulin resistance and restored endothelial nitric oxide synthase activation in the obese.

CONCLUSIONS

We observed profound endothelial insulin resistance in the visceral adipose tissue of obese humans which improved with FOXO-1 inhibition. FOXO-1 modulation may represent a novel therapeutic target to diminish vascular insulin resistance. In addition, characterization of endothelial insulin resistance in the adipose microenvironment may provide clues to mechanisms of systemic disease in human obesity.

Insulin resistance, diabetes, and cardiovascular risk

Obesity and type 2 diabetes mellitus (T2DM) are major drivers of cardiovascular disease (CVD). The link between environmental factors, obesity, and dysglycemia indicates that progression to diabetes with time occurs along a "continuum", not necessarily linear, which involves different cellular mechanisms including alterations of insulin signaling, changes in glucose transport, pancreatic beta cell dysfunction, as well as the deregulation of key genes involved in oxidative stress and inflammation. The present review critically addresses key pathophysiological aspects including (i) hyperglycemia and insulin resistance as predictors of CV outcome, (ii) molecular mechanisms underpinning the progression of diabetic vascular complications despite intensive glycemic control, and (iii) stratification of CV risk, with particular emphasis on emerging biomarkers. Taken together, these important aspects may contribute to the development of promising diagnostic approaches as well as mechanism-based therapeutic strategies to reduce CVD burden in obese and diabetic subjects.

Weight loss improves fasting flow-mediated vasodilation in adults: a meta-analysis of intervention studies

BACKGROUND

Obesity is associated with vascular endothelial dysfunction. Effects of weight loss on endothelial function are however not clear. Therefore, we performed a meta-analysis to quantify effects of weight loss on flow-mediated vasodilation (FMD) of the brachial artery, a measurement of endothelial function.

METHODS

Studies with experimental (RCTs) and quasi-experimental designs published before June 2014 were identified by a systematic search. Changes in FMD were defined as the difference between measurements before and after the study. For RCTs, changes were corrected for those in the no-weight loss control group. Summary estimates of weighted mean differences (WMDs) in FMD and 95% confidence intervals (CIs) were calculated using random-effect meta-analyses. The impact of subject characteristics, type of weight-loss treatment, and dietary composition on changes in FMD was also investigated.

RESULTS

Four RCTs involving 265 subjects were included. Weight loss increased FMD vs. control by 3.29% (95% CI: 0.98-5.59%; P = 0.005; mean weight loss: 8.6 kg). A total of 1517 subjects participated in 33 studies with 49 relevant study arms. It was estimated that each 10 kg decrease in body weight increased fasting FMD by 1.11% (95% CI: 0.47-1.76%; P = 0.001). Effects were more pronounced when participants had coexisting obesity-related morbidities. Also, effects may be larger when subjects received low-fat diets or weight-reduction regimens including exercise therapy or weight-loss medication.

CONCLUSION

Weight loss significantly improves fasting FMD in adults, which is a risk marker for cardiovascular disease. Effects may depend on subject characteristics, type of weight-loss treatment, and dietary composition.

Insulin resistance and skeletal muscle vasculature: significance, assessment and therapeutic modulators

Overnutrition and sedentarism are closely related to the alarming incidence of obesity and type 2 diabetes mellitus (DM2) in the Western world. Resistance to the actions of insulin is a common occurrence in conditions such as obesity, hypertension and DM2. In the skeletal muscle vasculature, insulin promotes vasodilation and its own transport across the vascular wall to reach its target tissue. Furthermore, insulin resistance (IR) in the skeletal muscle vasculature results in impaired skeletal muscle glucose uptake and altered whole-body glucose homeostasis. The development of different invasive and noninvasive techniques has allowed the characterization of the actions of insulin and other vasoactive hormones in the skeletal muscle vasculature in both health and disease. Current treatment strategies for DM2 do not necessarily address the impaired effect of insulin in the vasculature. Understanding the effects of insulin and other metabolically active hormones in the vasculature should facilitate the development of new therapeutic strategies targeted at the modulation of IR and improvement of whole-body glucose tolerance.

Insulin resistance: a key therapeutic target for cardiovascular risk reduction in obese patients?

The global obesity epidemic has emerged as one of the most important health care problems worldwide. Insulin resistance represents a prevalent pathophysiological abnormality that underlies mechanisms of cardiometabolic disease associated with obesity. Increasing basic, animal, and clinical data support a mechanistic link between insulin resistance and vascular dysfunction, and suggest that improving insulin sensitivity may represent a therapeutic target for combating atherosclerosis and cardiovascular disease. As clinical studies suggest that insulin resistance may play a key role in the cardiovascular benefit achieved with weight loss intervention, we will discuss our clinical perspective and provide evidence that obese individuals with hyperinsulinemia may derive the greatest improvement in vascular function with weight reduction. Lastly, we will address several important unanswered questions in the field that are likely to drive future clinical investigation.

High failure rate of the laparoscopic-adjustable gastric band as a primary bariatric procedure

BACKGROUND

Determinants of success of a bariatric procedure are many but paramount is the ability to durably produce significant and reliable weight loss. We sought to determine the primary success of the laparoscopic adjustable gastric band (LAGB) by defining failure as clinical weight loss failure with an intact band (excess weight loss [EWL]<20%) or band removal (terminal removal or conversion to a secondary bariatric procedure).

METHODS

A retrospective chart review was performed on patients who underwent an LAGB as a primary bariatric procedure between January 2003 and December 2007. Data collected included body mass index (BMI), weight, postoperative follow-up length, EWL, and adjustment number, as well as complications of the LAGB.

RESULTS

Sixteen of 120 patients had the band removed. Nine were terminally removed for unmanageable symptoms, and 7 were converted to an alternative bariatric procedure. The average follow-up for the 104 patients with an intact band was 4.8 years. The average EWL for successful intact bands was 44.9±19.4%; however, an additional 35.6% of patients had an EWL<20%. Patients with an EWL<20% had a significantly higher preoperative BMI and fewer band adjustments. In total, 44% of patients had band failure because of clinical weight loss failure (31%) or eventual band removal (13%).

CONCLUSION

This study finds that the LAGB failed as a primary bariatric procedure for 44% of patients because of either inadequate weight loss or adequate weight loss with unmanageable symptoms. This suggests that the LAGB should be abandoned as a primary bariatric procedure for the majority of morbidly obese patients because of its high failure rate.