Low plasma levels of adiponectin are associated with low risk for future cardiovascular events in patients with clinical evident vascular disease

Low level of adiponectin predicts the development of Nonalcoholic fatty liver disease: is it irrespective to visceral adiposity index, visceral adipose tissue thickness and other obesity indices?

We aimed to study the correlation of adiponectin level with insulin resistance (IR), carotid intima-media thickness (cIMT), and various obesity indices especially visceral adipose tissue (VAT) thickness, and visceral adiposity index (VAI), in patients with NAFLD (n = 41), T2D (n = 22), NAFLD + T2D (n = 41), and healthy subjects (n = 20). Results showed the median level of adiponectin in patients with NAFLD (2.97 μg/mL) and ones with NAFLD + T2D (3.21 μg/mL) is significantly lower rather than in controls (4.39 μg/mL). Moreover, VAI is the only predictor for adiponectin concentration in the combination of patient groups and also in all participants independent of IR and other obesity indices. Adiponectin level had also a positive correlation with cIMT and IR in NAFLD patients. Interestingly, lower level of adiponectin was associated with the presence of T2D, NAFLD, and NAFLD + T2D independent of IR and obesity indices. Collectively, it seems that VAI reflecting visceral adipose tissue function is a possible predictor of adiponectin level.

The prognostic role of RBP-4 and adiponectin in patients with peripheral arterial disease undergoing lower limb endovascular revascularization

BACKGROUND

RBP4 is an adipokine with an established role in atherosclerosis, while adiponectin has unique anti-inflammatory properties. We investigated the association of RBP4 and adiponectin with the presence of symptomatic peripheral artery disease (PAD) and their possible prognostic role in major adverse cardiovascular events (MACE).

METHODS

We enrolled 168 consecutive patients with symptomatic, established PAD, requiring revascularization by endovascular means of any or both of their lower limbs. 88 age- and sex-matched subjects with less than 2 classical cardiovascular risk factors served as controls. Clinical parameters, glycemic and lipid profile, RBP4 and adiponectin levels were assayed. The occurrence of MACE was recorded during the 6-month follow-up and patients were assigned to MACE and non-MACE subgroups.

RESULTS

The presence of symptomatic PAD was significantly correlated with age, diabetes, hsCRP, RBP4 and low adiponectin levels (p < 0.05). After adjustment for age, RBP4 (β = 0.498, p < 0.001), and adiponectin (β = -0.288, p < 0.001) levels remained as independent predictors of PAD presence in the whole study cohort. At baseline, MACE subgroup appeared with higher RBP-4 and hsCRP serum levels than non-MACE subgroup (p < 0.001), but no differences were detected for adiponectin (p = 0.758). Serum RBP4 levels remained independent predictor of MACE (β = 0.455, p < 0.001) after adjustment for traditional cardiovascular risk factors.

CONCLUSIONS

High RBP4 and low adiponectin serum levels are independently associated with PAD presence. In addition, RBP4 is an independent predictor of MACE incidence in symptomatic PAD patients.

Impact of Ramadan diurnal intermittent fasting on the metabolic syndrome components in healthy, non-athletic Muslim people aged over 15 years: a systematic review and meta-analysis

Studies on the impact of Ramadan diurnal intermittent fasting (RDIF) on the metabolic syndrome (MetS) components among healthy Muslims observing Ramadan month have yielded contradictory results. This comprehensive meta-analysis aimed to obtain a more stable estimate of the effect size of fasting during Ramadan on the MetS components, examine variability among studies, assess the generalisability of reported results and perform subgroup analyses for associated factors. We searched the CINAHL, Cochrane, EBSCOhost, Google Scholar, ProQuest Medical, PubMed/MEDLINE, ScienceDirect, Scopus and Web of Science databases for relevant studies published from 1950 to March 2019. The MetS components analysed were: waist circumference (WC), systolic blood pressure (SBP), fasting plasma/serum glucose (FG), TAG, and HDL-cholesterol. We identified eighty-five studies (4326 participants in total) that were conducted in twenty-three countries between 1982 and 2019. RDIF-induced effect sizes for the MetS components were: small reductions in WC (no. of studies K = 24, N 1557, Hedges' g = -0·312, 95 % CI -0·387, -0·236), SBP (K = 22, N 1172, Hedges' g = -0·239, 95 % CI -0·372, -0·106), FG (K = 51, N 2318, Hedges' g = -0·101, 95 % CI -0·260, 0·004) and TAG (K = 63, N 2862, Hedges' g = -0·088, 95 % CI -0·171, -0·004) and a small increase in HDL-cholesterol (K = 57, N 2771, Hedges' g = 0·150, 95 % CI 0·064, 0·236). We concluded that among healthy people, RDIF shows small improvement in the five MetS components: WC, SBP, TAG, FG and HDL.

Cardiovascular Adiponectin Resistance: The Critical Role of Adiponectin Receptor Modification

For the past two decades, a great deal of research has been published concerning adiponectin (APN), an abundant protein responsible for regulating numerous biologic functions including antioxidative, antinitrative, anti-inflammatory, and cardioprotective effects. A review of APN and its two major receptors is timely because of new findings concerning the mechanisms by which APN signaling may be altered in pathologic processes such as diabetes and heart failure. In this review we elaborate on currently known information regarding the physiologic role of APN and the known mechanisms underlying pathologic APN resistance - namely, APN receptor downregulation and phosphorylation - and provide insight regarding the future directions of APN research including an assessment of the clinical applicability of preventing pathologic post-translational modification of the APN receptor.

Novel Biomarkers to Improve the Prediction of Cardiovascular Event Risk in Type 2 Diabetes Mellitus

BACKGROUND

We evaluated the ability of 23 novel biomarkers representing several pathophysiological pathways to improve the prediction of cardiovascular event (CVE) risk in patients with type 2 diabetes mellitus beyond traditional risk factors.

METHODS AND RESULTS

We used data from 1002 patients with type 2 diabetes mellitus from the Second Manifestations of ARTertial disease (SMART) study and 288 patients from the European Prospective Investigation into Cancer and Nutrition-NL (EPIC-NL). The associations of 23 biomarkers (adiponectin, C-reactive protein, epidermal-type fatty acid binding protein, heart-type fatty acid binding protein, basic fibroblast growth factor, soluble FMS-like tyrosine kinase-1, soluble intercellular adhesion molecule-1 and -3, matrix metalloproteinase [MMP]-1, MMP-3, MMP-9, N-terminal prohormone of B-type natriuretic peptide, osteopontin, osteonectin, osteocalcin, placental growth factor, serum amyloid A, E-selectin, P-selectin, tissue inhibitor of MMP-1, thrombomodulin, soluble vascular cell adhesion molecule-1, and vascular endothelial growth factor) with CVE risk were evaluated by using Cox proportional hazards analysis adjusting for traditional risk factors. The incremental predictive performance was assessed with use of the c-statistic and net reclassification index (NRI; continuous and based on 10-year risk strata 0-10%, 10-20%, 20-30%, >30%). A multimarker model was constructed comprising those biomarkers that improved predictive performance in both cohorts. N-terminal prohormone of B-type natriuretic peptide, osteopontin, and MMP-3 were the only biomarkers significantly associated with an increased risk of CVE and improved predictive performance in both cohorts. In SMART, the combination of these biomarkers increased the c-statistic with 0.03 (95% CI 0.01-0.05), and the continuous NRI was 0.37 (95% CI 0.21-0.52). In EPIC-NL, the multimarker model increased the c-statistic with 0.03 (95% CI 0.00-0.03), and the continuous NRI was 0.44 (95% CI 0.23-0.66). Based on risk strata, the NRI was 0.12 (95% CI 0.03-0.21) in SMART and 0.07 (95% CI -0.04-0.17) in EPIC-NL.

CONCLUSIONS

Of the 23 evaluated biomarkers from different pathophysiological pathways, N-terminal prohormone of B-type natriuretic peptide, osteopontin, MMP-3, and their combination improved CVE risk prediction in 2 separate cohorts of patients with type 2 diabetes mellitus beyond traditional risk factors. However, the number of patients reclassified to a different risk stratum was limited.

Ion Channels in Obesity: Pathophysiology and Potential Therapeutic Targets

Obesity is a multifactorial disease related to metabolic disorders and associated with genetic determinants. Currently, ion channels activity has been linked to many of these disorders, in addition to the central regulation of food intake, energetic balance, hormone release and response, as well as the adipocyte cell proliferation. Therefore, the objective of this work is to review the current knowledge about the influence of ion channels in obesity development. This review used different sources of literature (Google Scholar, PubMed, Scopus, and Web of Science) to assess the role of ion channels in the pathophysiology of obesity. Ion channels present diverse key functions, such as the maintenance of physiological homeostasis and cell proliferation. Cell biology and pharmacological experimental evidences demonstrate that proliferating cells exhibit ion channel expression, conductance, and electrical properties different from the resting cells. Thereby, a large variety of ion channels has been identified in the pathogenesis of obesity such as potassium, sodium, calcium and chloride channels, nicotinic acetylcholine receptor and transient receptor potential channels. The fundamental involvement of these channels on the generation of obesity leads to the progress in the knowledge about the mechanisms responsible for the obesity pathophysiology, consequently emerging as new targets for pharmacological modulation.

The relation between body iron stores and adipose tissue function in patients with manifest vascular disease

BACKGROUND

We investigated whether plasma ferritin levels through the pro-inflammatory effects of free iron are associated with adipose tissue dysfunction in a relevant population of patients with manifest vascular disease who would potentially benefit the most from further aetiological insights.

MATERIALS AND METHODS

In a cohort of 355 patients with vascular diseases, the association between plasma ferritin and adiponectin levels was quantified using linear regression analysis. Interleukin-6 and adiponectin levels were measured in medium from pre-adipocytes and adipocytes after incubation with increasing concentrations of Fe(III)-citrate and after co-incubation with iron chelators or radical scavengers.

RESULTS

Increasing ferritin plasma concentrations were not related to plasma adiponectin levels in patients without (β -0·13; 95% CI -0·30 to 0·04) or with the metabolic syndrome (β -0·04; 95% CI -0·17 to 0·10). Similar results were found in patients who developed a new cardiovascular event in the follow-up period. In vitro, incubation with increasing concentrations of Fe(III)-citrate-induced inflammation in pre-adipocyte cultures as witnessed by increased IL-6 secretion at 30 μm Fe(III)-citrate vs. control (500 ± 98 pg/mL vs. 194 ± 31 pg/mL, P = 0·03). Co-incubation of pre-adipocytes with iron chelators or radical scavengers prevented this inflammatory response. Incubation of adipocytes with 30 μm Fe(III)-citrate did not influence adiponectin secretion compared with control.

CONCLUSIONS

In patients with vascular disease, there is no association between plasma ferritin and adiponectin levels. In vitro, free iron induces an inflammatory response in pre-adipocytes, but not in adipocytes. This response was blocked by co-incubation with iron chelators or radical scavengers. Adiponectin secretion by adipocytes was not influenced by free iron.

Adipocyte reporter assays: application for identification of anti-inflammatory and antioxidant properties of mangosteen xanthones

SCOPE

Three fluorescence biosensors were developed based on a 3T3-L1 preadipocyte line that stably expressed Nfkb-RE/GFP, Fabp4-P/CFP, and Nrf2-P/YFP fluorescent reporters. We hypothesized that nutraceuticals' inflammatory, adipogenic, and antioxidant status will be identified based on the change in fluorescence in reporter adipocytes. We validated these assays with activators of NFκB, FABP4-regulating peroxisome proliferator activated receptor gamma, NFR2 and, thereafter, tested known and unknown properties of mangostines (MGs), the xanthone metabolites in mangosteen fruit.

METHODS AND RESULTS

We validated inflammatory and adipogenic properties of α-MG using an Nfkb-RE/GFP biosensor assay. Next, we identified unique properties of γ-MG, a minor MG xanthone. γ-MG suppressed adipogenesis and expression of adiponectin, but inhibited the Nfkb-RE/GFP reporter and secretion of inflammatory monocyte chemotactic protein 1 as compared to the control adipocytes. We found that the inhibition of adipogenesis and Nfkb-mediated inflammation depends on a dose-dependent reduction of Nrf2 promoter activity by α-MG. The Nrf2 inhibition resulted in the reduced Pparg expression. α-MG did not directly influence Pparg activity in Fabp4-P/CFP adipocytes.

CONCLUSION

α-MG-mediated antioxidant response via Nrf2 is a mechanism preventing adipogenesis and inflammation in adipocytes. Combined application of high-throughput biosensors could provide an effective platform for the identification of nutraceuticals and the mechanism of their actions in adipocytes and, potentially, in obese patients.

Adiponectin and incident coronary heart disease and stroke. A systematic review and meta-analysis of prospective studies

The plasma concentration of adiponectin, an adipokine that has anti-inflammatory, anti-atherogenic and insulin sensitizing properties, is lower in obese subjects and could therefore be a target for therapy. In order to review and meta-analyse prospective cohort studies investigating adiponectin concentration and the risk for incident coronary heart disease (CHD) or stroke, a systematic search of MEDLINE, EMBASE and Cochrane databases was performed. Two independent reviewers selected prospective cohort studies investigating the relationship between adiponectin level and incident CHD or stroke using 'adiponectin' and 'cardiovascular disease' or 'stroke' and their synonyms, excluding patients with clinically manifest vascular disease. Random-effects models were used to calculate pooled relative risks (RRs) and 95% confidence intervals (95% CI). Generalized least squares regression was used to assess dose-response relationships for adiponectin concentrations from studies that provided RRs solely based upon categorical data regression. In total, 16 prospective cohort studies, comprising 23,919 patients and 6,870 CHD or stroke outcome events, were included in the meta-analyses. An increase of 1 standard deviation in log-transformed adiponectin did not lower the risk for CHD (RR 0.97; 95% CI 0.86-1.09). A 10 μg mL(-1) increase in adiponectin conferred a RR of 0.91 (95% CI 0.80-1.03) for CHD and a RR 1.01 (95% CI 0.97-1.06) for stroke. In conclusion, plasma adiponectin is not related to the risk for incident CHD or stroke.

Adiponectin in renal disease--a review of the evidence as a risk factor for cardiovascular and all-cause mortality

Adiponectin, an adipokine, was discovered in 1995. The initial evidence led to the study of adiponectin as a determinant of insulin sensitivity and blood glucose levels. The literature then evolved to reports of the inverse association of adiponectin with incident Type 2 diabetes mellitus and coronary heart disease. Shortly thereafter, reports of a positive association with heart failure and mortality appeared and were replicated. We review here the basic science evidence and clinical studies of the role of renal function and kidney disease as a determinant of adiponectin.

Dietary fat and heart failure: moving from lipotoxicity to lipoprotection

There is growing evidence suggesting that dietary fat intake affects the development and progression of heart failure. Studies in rodents show that in the absence of obesity, replacing refined carbohydrate with fat can attenuate or prevent ventricular expansion and contractile dysfunction in response to hypertension, infarction, or genetic cardiomyopathy. Relatively low intake of n-3 polyunsaturated fatty acids from marine sources alters cardiac membrane phospholipid fatty acid composition, decreases the onset of new heart failure, and slows the progression of established heart failure. This effect is associated with decreased inflammation and improved resistance to mitochondrial permeability transition. High intake of saturated, monounsaturated, or n-6 polyunsaturated fatty acids has also shown beneficial effects in rodent studies. The underlying mechanisms are complex, and a more thorough understanding is needed of the effects on cardiac phospholipids, lipid metabolites, and metabolic flux in the normal and failing heart. In summary, manipulation of dietary fat intake shows promise in the prevention and treatment of heart failure. Clinical studies generally support high intake of n-3 polyunsaturated fatty acids from marine sources to prevent and treat heart failure. Additional clinical and animals studies are needed to determine the optimal diet in terms of saturated, monounsaturated, and n-6 polyunsaturated fatty acids intake for this vulnerable patient population.

Adiponectin protects endothelial cells from the damages induced by the intermittent high level of glucose

Globular adiponectin (gAd) has anti-atherogenic effects on the vascular wall. Intermittent hyperglycemia induces endothelial cells (ECs) injury but the physiological factors that may protect against ECs damage are largely unknown. In the present study, we investigated the effect of gAd on ECs dysfunction induced by intermittent high glucose. The gAd significantly attenuated intermittent high glucose-induced apoptosis and oxidative stress in human umbilical vein endothelial cells. This was achieved by decreasing caspase-3 and 3-nitrotyrosine protein expression, increasing nitric oxide (NO) secretion and phosphorylation of Akt, AMPK, and endothelial nitric oxide synthase protein expression. Pretreatment with a phosphatidylinositol 3' kinase (PI3K) inhibitor, LY294002, partly reversed adiponectin's anti-apoptotic effect. Taken together, our results indicate that gAd acts as a critical physiological factor which protects against fluctuating high glucose-induced endothelial damage. It may act via attenuating apoptosis and increasing synthesis of NO through both the PI3K/AKT and AMPK signaling pathway to reduce oxidative stress and cell apoptosis.

Pharmacological and non-pharmacological interventions to influence adipose tissue function

Obesity is associated with metabolic derangements such as insulin resistance, inflammation and hypercoagulobility which can all be understood as consequences of adipose tissue dysfunction. The potential role for adipose tissue derived cytokines and adipokines in the development of vascular disease and diabetes may produce a clinical need to influence adipose tissue function. Various pharmacological and non-pharmacological interventions affect plasma cytokine and adipokine levels. The effects of these interventions depend on weight loss per se, changes in fat distribution without weight loss and/or direct effects on adipose tissue inflammation.

Weight loss, as a result of diet, pharmacology and surgery, positively influences plasma adipokines and systemic inflammation. Several classes of drugs influence systemic inflammation directly through their anti-inflammatory actions. PPAR-γ agonism positively influences adipose tissue inflammation in several classes of intervention such as the thiazolidinediones and perhaps salicylates, CB1-antagonists and angiotensin II receptor blockers. Furthermore, within drug classes there are differential effects of individual pharmacologic agents on adipose tissue function.

It can be concluded that several commonly used pharmacological and non-pharmacological interventions have unintended influences on adipose tissue function. Improving adipose tissue function may contribute to reducing the risk of vascular diseases and the development of type 2 diabetes.

Association of adiponectin, resistin, and vascular inflammation: analysis with 18F-fluorodeoxyglucose positron emission tomography

OBJECTIVE

Adiponectin and resistin are adipokines that are linked to obesity, inflammation, and atherosclerosis. (18)F-Fluorodeoxyglucose (FDG) positron emission tomography is a promising imaging technique that can be used to evaluate vascular inflammation.

METHODS AND RESULTS

We measured adiponectin and resistin levels, as well as traditional cardiovascular risk factors, in 60 obese subjects and 60 nonobese controls. In addition, we compared carotid intima-media thickness and target-to-background ratio (TBR) measured using (18)F-fluorodeoxyglucose-positron emission tomography/computed tomography. The mean TBR values were significantly higher in the obese group compared with normal subjects, although their mean carotid intima-media thickness levels were not significantly different. Serum adiponectin levels showed a significant negative correlation with mean TBR values (r = -0.215, P = 0.020), whereas resistin levels were positively correlated with mean TBR values (r = 0.214, P = 0.021). Multiple linear regression analysis showed that mean TBR values were independently associated with body mass index, high-sensitivity C-reactive protein, and resistin levels (R(2) = 0.308).

CONCLUSIONS

Adiponectin and resistin may be useful as biomarkers to reflect vascular inflammation. In particular, resistin levels were independently associated with vascular inflammation even after adjusting for other cardiovascular risk factors.

Review: Adiponectin for prediction of cardiovascular risk?

Adiponectin is an endogenous insulin-sensitising and anti-inflammatory hormone, released by the adipose tissue. Because of its in vitro effects on endothelial cells, macrophages and vascular smooth muscle cells, adiponectin is thought to have anti-atherogenic properties. Moreover, findings from the Health Professionals Follow-up Studies and other cohort studies, mainly in male populations, suggest that adiponectin may be an independent predictor for cardiovascular risk. This, however, was not confirmed by subsequent studies that included female subjects, different ethnicities and patients with established coronary artery disease. The present article briefly summarises recent findings regarding the potential role of adiponectin as a predictor of risk and its biological role.

Br J Diabetes Vasc Dis 2009;9: 150—154

Hypoadiponectinemia in lipodystrophic HIV individuals: a metabolic marker of subclinical cardiac damage

BACKGROUND AND AIM

To evaluate cardiovascular abnormalities in highly active antiretroviral therapy (HAART) treated HIV patients with no signs or symptoms of cardiovascular impairment, and to assess the relative role of multiple concomitant risk factors.

METHODS AND RESULTS

Forty-four consecutive HIV subjects (mean age 41+/-6 yrs) were enrolled. Inclusion criteria were HIV infection, CD4+cell count>150/ml, HAART treatment for at least 4 years. Metabolic serum levels, morphological and functional echocardiographic parameters were assessed in all subjects. Sixteen healthy age and sex matched subjects with no cardiovascular risk factors were recruited as controls. HIV patients showed increased left ventricular mass index with reduced mid-wall fractional shortening (mFS) when compared to controls (50.2+/-10.5 vs. 38.6+/-14.4, p=0.05 and 18.3+/-0.6 vs. 21.9+/-0.7, p<0.05, respectively). Twenty-nine patients were lipodystrophic (LD) and showed a longer HAART period (p=0.0004) and greater use of protease inhibitors (PI) (p=0.001). Coronary flow reserve (CFR) was significantly reduced in HIV patients as compared to controls (p<0.0001), as it was in LD subjects when compared to non-lipodystrophic ones (NLD) (p<0.001). Adiponectin concentrations were found to be significantly lower in LD subjects than in NLD ones (7.8+/-0.8 vs. 13.8+/-1.2 microg/ml, p=0.01), and showed a direct correlation with CFR. In multiple regression analysis, insulin, HDL and adiponectin accounted for 63% of CFR variations.

CONCLUSIONS

Left ventricular hypertrophy, depressed mFS and reduced CFR represent the main signs of subclinical cardiac damage in HIV subjects treated with HAART. Hypoadiponectinemia in these subjects seems to be a metabolic risk factor of cardiovascular impairment.

Adipose tissue and the metabolic syndrome: focusing on adiponectin and several novel adipokines

The metabolic syndrome represents a cluster of metabolic risk factors that predispose an individual to an increased risk for Type 2 diabetes, cardiovascular diseases and their associated morbidity and mortality. Visceral obesity is thought to be a major culprit. Adipokines secreted from the adipose tissue are now believed to be key factors mediating the metabolic and inflammatory effects of obesity. In this review, we shall examine the evidence suggesting that several novel adipokines, adiponectin, adipocyte fatty acid-binding protein, retinol-binding protein-4 and lipocalin-2, may hold promise as important clinical biomarkers to identify individuals at risk for the metabolic syndrome and related comorbidities.

Factors contributing to the risk of cardiovascular disease reflected by plasma adiponectin: data from the coronary risk factors for atherosclerosis in women (CORA) study

OBJECTIVE

An inverse association of adiponectin with coronary heart disease (CHD) has been reported, but the results are inconsistent. We used data from the CORA study to investigate into plasma concentrations of adiponectin and factors that may mediate the link to incident CHD.

DESIGN

The CORA study is a population-based case-control study on 200 women with incident CHD and 255 age-matched controls.

RESULTS

Plasma concentrations of adiponectin were significantly lower in women with CHD (p<0.0001), and in women with BMI >or=25 kg/m(2) (p<0.02), even more so with central obesity (WHR >or=0.85), prevalent diabetes or insulin resistance (HOMA-IR >or=3.8), or low HDL-cholesterol (<50mg/dl), and in smokers (each p<0.0001). Adiponectin also correlated with intake of fruit and vegetables, meat and sausage and alcohol as dietary markers of cardiovascular risk. Strikingly, the trend towards lower adiponectin concentrations with increasing BMI or waist circumference was less marked than the difference of adiponectin between CHD cases and controls. In a logistic regression model the odds ratio of adiponectin of 0.943 per 1 microg/ml (CI 0.919-0.968, p<0.0001) for risk of CHD was progressively reduced by elevated WHR, obesity-related risk factors, smoking, and dietary parameters.

CONCLUSIONS

Plasma adiponectin indicates protection from CHD in women that is attenuated by combined effects of central obesity and dependent risk factors, parameters of nutrition and smoking. Thus, the impact of adiponectin goes beyond its relation to central adiposity, but may also reflect independent effects of lifestyle.