Higher circulating omentin is associated with increased risk of primary cardiovascular events in individuals with diabetes

Improving 10-year cardiovascular risk prediction in patients with type 2 diabetes with metabolomics

BACKGROUND

Existing cardiovascular risk prediction models still have room for improvement in patients with type 2 diabetes who represent a high-risk population. This study evaluated whether adding metabolomic biomarkers could enhance the 10-year prediction of major adverse cardiovascular events (MACE) in these patients.

METHODS

Data from 10,257 to 1,039 patients with type 2 diabetes from the UK Biobank (UKB) and the German ESTHER cohort, respectively, were used for model derivation, internal and external validation. A total of 249 metabolites were measured with nuclear magnetic resonance (NMR) spectroscopy. Sex-specific LASSO regression with bootstrapping identified significant metabolites. The enhanced model's predictive performance was evaluated using Harrell's C-index.

RESULTS

Seven metabolomic biomarkers were selected by LASSO regression for enhanced MACE risk prediction (three for both sexes, three male- and one female-specific metabolite(s)). Especially albumin and the omega-3-fatty-acids-to-total-fatty-acids-percentage among males and lactate among females improved the C-index. In internal validation with 30% of the UKB, adding the selected metabolites to the SCORE2-Diabetes model increased the C-index statistically significantly (P = 0.037) from 0.660 to 0.678 in the total sample. In external validation with ESTHER, the C-index increase was higher (+ 0.043) and remained statistically significant (P = 0.011).

CONCLUSIONS

Incorporating seven metabolomic biomarkers in the SCORE2-Diabetes model enhanced its ability to predict MACE in patients with type 2 diabetes. Given the latest cost reduction and standardization efforts, NMR metabolomics has the potential for translation into the clinical routine.

Omentin roles in physiology and pathophysiology: an up-to-date comprehensive review

Omentin (intelectin) was first detected in the visceral omental adipose tissue. It has mainly two isoforms, omentin-1 and -2, with isoform-1 being the main form in human blood. It possesses insulin-sensitizing, anti-inflammatory, anti-atherogenic, cardio-protective, and oxidative stress-decreasing effects. Omentin's cardiovascular protective actions are caused by the improved endothelial cell survival and function, increased endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) bioavailability, enhanced vascular smooth muscle cells (VSMCs) relaxation with reduced proliferation, decreased inflammation, and suppressed oxidative stress. Omentin may also have a potential role in different cancer types and rheumatic diseases. Thus, omentin is an excellent therapeutic target in many diseases, including diabetes mellitus (DM), metabolic syndrome (MetS), cardiovascular diseases (CVDs), inflammatory diseases, and cancer. This review demonstrates the physiological functions of omentin in ameliorating insulin resistance (IR), vascular function, and inflammation and its possible share in managing obesity-linked diseases, such as metabolic disorders, DM, and cardiovascular conditions.

Omentin-1 and diabetic foot

Introduction: Diabetic foot disease is an advanced complication of diabetes mellitus, which is associated with severe invalidization and high mortality rate among affected people. Many factors are involved in its pathogenesis but not all of them are fully elucidated. Objectives: Adipose tissue and its hormones - adipokines, are related to diabetic complications and metabolic disorders. Until now, there are limited data on their role in diabetic foot. The aim of this cross-sectional study is to determine the levels of the adipokine omentin-1 in people with and without diabetic foot disease and to look for its potential involvement in this complication. Methods: Eighty patients with type 2 diabetes and mean age of 60.8±10.5 years were included in this study. They were divided into two groups: with (n=36) and without (n=44) diabetic foot disease. Standard antrometric, clinical and laboratory tests were made. Body composition was analyzed by bioelectrical impedance based device. Serum omentin-1 was measured using ELISA method. Results: Levels of omentin-1 were significantly higher among people with diabetic foot disease (700.2±345.1 ng/ml), compared to the other group (560.2±176.7 ng/ml). This difference remained significant even after adjusting for potential confounders. In a regression model omentin-1 proved its predictive value for development of diabetic foot. Conclusion: Adipokines, and particularly omentin-1, might be included in the pathogenesis of diabetic foot disease.

Omentin reduces venous neointimal hyperplasia in arteriovenous fistula through hypoxia-inducible factor-1 alpha inhibition

Arteriovenous fistula (AVF) failure often involves venous neointimal hyperplasia (VNH) driven by elevated hypoxia-inducible factor-1 alpha (HIF-1α) in the venous wall. Omentin, known for its anti-inflammatory and anti-hyperplasia properties, has an uncertain role in early AVF failure. This study investigates omentin's impact on VNH using a chronic renal failure (CRF) rabbit model. The CRF rabbit model of AVF received omentin-expressing adenoviral vector or control β-gal vector to assess omentin's effects on VNH. Human vascular smooth muscle cells (HVSMCs), stimulated with tumor necrosis factor-α (TNF-α), were exposed to recombinant human omentin (Rh-OMT) to study its influence on cell proliferation and migration. The AMP-activated protein kinase (AMPK) inhibitor compound C and the mammalian target of rapamycin (mTOR) activator MHY1485 were employed to explore omentin's mechanisms in VNH reduction through HIF-1α inhibition. Omentin treatment reduced VNH in CRF rabbits, concomitant with HIF-1α down-regulation and the suppression of downstream factors, including vascular endothelial growth factor and matrix metalloproteinases. Rh-OMT inhibited TNF-α-induced HVSMC proliferation and migration by modulating both cell cycle and cell adhesion proteins. Additionally, omentin reduced HIF-1α expression through the AMPK/mTOR pathway activation. Notably, the blockade of AMPK/mTOR signaling reversed omentin-mediated inhibition of VNH, cell proliferation, and migration, both in vivo and in vitro. In conclusion, omentin mitigates VNH post-AVF creation by restraining HIF-1α via AMPK/mTOR signaling. Strategies boosting circulating omentin levels may offer promise in averting AVF failure.

Determination of serum and gingival crevicular fluid levels of omentin in healthy and rheumatoid arthritis subjects with and without periodontitis

OBJECTIVE

The aim of this study was to assess and correlate the serum and GCF levels of omentin with the periodontal status of rheumatoid arthritis (RA) patients with and without periodontitis.

METHODS

Forty-four patients were divided into four groups: group H: 11 systemically and periodontally healthy subjects; group P: 11 systemically healthy subjects with periodontitis; group RA: 11 periodontally healthy subjects with rheumatoid arthritis and group RA + P: 11 rheumatoid arthritis subjects with periodontitis. Periodontal parameters (plaque index, modified gingival index, probing depth, and clinical attachment level) were recorded and serum and GCF samples were collected for the estimation of omentin using ELISA.

RESULTS

The mean value of plaque index, modified gingival index, probing depth, and clinical attachment level were significantly higher whereas serum and GCF omentin levels were found to be decreased in group IV when compared to the other groups. The significant correlation was found between the serum and GCF omentin levels with all the periodontal parameters.

CONCLUSION

The omentin level in serum and GCF was found to be lower in RA patients with periodontitis. It is also inversely correlated with the periodontal parameters. Thus, omentin can serve as a significant diagnostic and therapeutic tool in both periodontal and rheumatoid disease.

Omentin associates with serum metabolite profiles indicating lower diabetes risk: KORA F4 Study

INTRODUCTION

Circulating omentin levels have been positively associated with insulin sensitivity. Although a role for adiponectin in this relationship has been suggested, underlying mechanisms remain elusive. In order to reveal the relationship between omentin and systemic metabolism, this study aimed to investigate associations of serum concentrations of omentin and metabolites.

RESEARCH DESIGN AND METHODS

This study is based on 1124 participants aged 61-82 years from the population-based KORA (Cooperative Health Research in the Region of Augsburg) F4 Study, for whom both serum omentin levels and metabolite concentration profiles were available. Associations were assessed with five multivariable regression models, which were stepwise adjusted for multiple potential confounders, including age, sex, body mass index, waist-to-hip ratio, lifestyle markers (physical activity, smoking behavior and alcohol consumption), serum adiponectin levels, high-density lipoprotein cholesterol, use of lipid-lowering or anti-inflammatory medication, history of myocardial infarction and stroke, homeostasis model assessment 2 of insulin resistance, diabetes status, and use of oral glucose-lowering medication and insulin.

RESULTS

Omentin levels significantly associated with multiple metabolites including amino acids, acylcarnitines, and lipids (eg, sphingomyelins and phosphatidylcholines (PCs)). Positive associations for several PCs, such as diacyl (PC aa C32:1) and alkyl-alkyl (PC ae C32:2), were significant in models 1-4, whereas those with hydroxytetradecenoylcarnitine (C14:1-OH) were significant in all five models. Omentin concentrations were negatively associated with several metabolite ratios, such as the valine-to-PC ae C32:2 and the serine-to-PC ae C32:2 ratios in most models.

CONCLUSIONS

Our results suggest that omentin may influence insulin sensitivity and diabetes risk by changing systemic lipid metabolism, but further mechanistic studies investigating effects of omentin on metabolism of insulin-sensitive tissues are needed.

Omentin: A Key Player in Glucose Homeostasis, Atheroprotection, and Anti-Inflammatory Potential for Cardiovascular Health in Obesity and Diabetes

Omentin is an adipokine mainly produced by visceral fat tissue. It has two isoforms, omentin-1 and omentin-2. Omentin-1 is predominantly secreted by visceral adipose tissue, derived specifically from the stromal vascular fraction cells of white adipose tissue (WAT). Levels of omentin-1 are also expressed in other WAT depots, such as epicardial adipose tissue. Omentin-1 exerts several beneficial effects in glucose homeostasis in obesity and diabetes. In addition, research has suggested that omentin-1 may have atheroprotective (protective against the development of atherosclerosis) and anti-inflammatory effects, potentially contributing to cardiovascular health. This review highlights the potential therapeutic targets of omentin-1 in metabolic disorders.

Inter-organ crosstalk during development and progression of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is characterized by tissue-specific insulin resistance and pancreatic β-cell dysfunction, which result from the interplay of local abnormalities within different tissues and systemic dysregulation of tissue crosstalk. The main local mechanisms comprise metabolic (lipid) signalling, altered mitochondrial metabolism with oxidative stress, endoplasmic reticulum stress and local inflammation. While the role of endocrine dysregulation in T2DM pathogenesis is well established, other forms of inter-organ crosstalk deserve closer investigation to better understand the multifactorial transition from normoglycaemia to hyperglycaemia. This narrative Review addresses the impact of certain tissue-specific messenger systems, such as metabolites, peptides and proteins and microRNAs, their secretion patterns and possible alternative transport mechanisms, such as extracellular vesicles (exosomes). The focus is on the effects of these messengers on distant organs during the development of T2DM and progression to its complications. Starting from the adipose tissue as a major organ relevant to T2DM pathophysiology, the discussion is expanded to other key tissues, such as skeletal muscle, liver, the endocrine pancreas and the intestine. Subsequently, this Review also sheds light on the potential of multimarker panels derived from these biomarkers and related multi-omics for the prediction of risk and progression of T2DM, novel diabetes mellitus subtypes and/or endotypes and T2DM-related complications.

Association of Intelectin 1 Gene rs2274907 A > T Polymorphism with Obesity, Type 2 Diabetes, Serum Intelectin-1 Levels and Lipid Profiles in Turkish Adults

The anti-inflammatory adipokine intelectin-1, which is encoded by the ITLN1 gene, is hypothesized to be linked to the pathogenesis of type 2 diabetes (T2DM) and obesity. The purpose of this study was to examine the effect of the ITLN1 gene polymorphism rs2274907 on obesity and T2DM in Turkish adults. The impact of genotype on lipid profiles and serum intelectin levels in the obese and diabetes groups was also investigated. Randomly selected 2266 adults (mean age, 55.0 ± 11.7 years; 51.2% women) participating in the population-based Turkish adult risk factor study were cross-sectionally analyzed. The genotyping of rs2274907 A > T polymorphism was performed by using the hybridization probe based LightSNiP assay in real-time PCR. T2DM were defined using the criteria of the American Diabetes Association. Obesity was described as Body mass index ≥ 30 kg/m2. Statistical analyses were used to investigate the association of genotypes with clinical and biochemical measurements. According to findings, there was no vital connection between the rs2274907 polymorphism and obesity, T2DM, or serum intelectin-1 level. The TA+AA carriers had significantly higher triglyceride levels (p = 0.007) compared with the TT carriers in both obese and T2DM women when adjusted for relevant covariates. ITLN1 rs2274907 polymorphism is not correlated with the risk of obesity and T2DM and not affect serum ITLN1 levels in Turkish adults. However, this polymorphism appears to be important in regulating triglyceride levels in obese and diabetic women.

Fat and inflammation: adipocyte-myeloid cell crosstalk in atherosclerosis

Adipose tissue inflammation has been implicated in various chronic inflammatory diseases and cancer. Perivascular adipose tissue (PVAT) surrounds the aorta as an extra layer and was suggested to contribute to atherosclerosis development. PVAT regulates the function of endothelial and vascular smooth muscle cells in the aorta and represent a reservoir for various immune cells which may participate in aortic inflammation. Recent studies demonstrate that adipocytes also express various cytokine receptors and, therefore, may directly respond to inflammatory stimuli. Here we will summarize current knowledge on immune mechanisms regulating adipocyte activation and the crosstalk between myeloid cells and adipocytes in pathogenesis of atherosclerosis.

Association of Serum Omentin-1 Concentration with the Content of Adipose Tissue and Glucose Tolerance in Subjects with Central Obesity

Omentin is one of the few adipokines with potentially beneficial metabolic effects. The main aim of this study was to determine the association between serum omentin-1 levels and the occurrence of central obesity and abnormal glucose tolerance, taking into account gender. The study involved 88 participants aged 30-60, including 47 women and 41 men. Two subgroups among the obese subjects were distinguished-those with normal and abnormal glucose tolerance. Anthropometric and biochemical examinations and blood pressure measurements were performed. Omentin-1 concentrations were significantly lower among patients with obesity compared to those without obesity (p = 0.027) and, similarly, comparing men with abnormal glucose tolerance with men with normal glucose tolerance (p = 0.035). In contrast, no such pattern was observed in women. The multivariable regression model showed a significant effect of gender status and important factors of tissue insulin sensitivity, such as OGGT results, WHR and amount of body fat, on the variability of serum omentin-1 concentration in the entire study population (R²adj. = 13.7%; p = 0.003). High omentin-1 levels found in men with obesity and normal glucose tolerance suggest that omentin-1 protects against metabolic disorders associated with obesity in the male population.

Targeting adipokines in polycystic ovary syndrome and related metabolic disorders: from experimental insights to clinical studies

Polycystic ovary syndrome (PCOS) affects approximately 15% of women of reproductive age worldwide. It is the most prevalent endocrine disorder with marked risks for female infertility, type 2 diabetes mellitus (T2DM), psychiatric disorders and gynecological cancers. Although the pathophysiology of PCOS remains largely elusive, growing evidence suggests a close link with obesity and its related metabolic disorders. As a highly active endocrine cell population, hypertrophic adipocytes in obesity have disturbed production of a vast array of adipokines, biologically active peptides that exert pleiotropic effects on homeostatic regulation of glucose and lipid metabolism. In parallel with their crucial roles in the pathophysiology of obesity-induced metabolic diseases, adipokines have recently been identified as promising targets for novel therapeutic strategies for multiple diseases. Current treatments for PCOS are suboptimal with insufficient alleviation of all symptoms. Novel findings in adipokine-targeted agents may provide important insight into the development of new drugs for PCOS. This Review presents an overview of the current understanding of mechanisms that link PCOS to obesity and highlights emerging evidence of adipose-ovary crosstalk as a pivotal mediator of PCOS pathogenesis. We summarize recent findings of preclinical and clinical studies that reveal the therapeutic potential of adipokine-targeted novel approaches to PCOS and its related metabolic disorders. We also discuss the critical gaps in knowledge that need to be addressed to guide the development of adipokine-based novel therapies for PCOS.

Omentin1 ameliorates myocardial ischemia-induced heart failure via SIRT3/FOXO3a-dependent mitochondrial dynamical homeostasis and mitophagy

Background

Adipose tissue-derived adipokines are involved in various crosstalk between adipose tissue and other organs. Omentin1, a novel adipokine, exerts vital roles in the maintenance of body metabolism, insulin resistance and the like. However, the protective effect of omentin1 in myocardial ischemia (MI)-induced heart failure (HF) and its specific mechanism remains unclear and to be elucidated.

Methods

The model of MI-induced HF mice and oxygen glucose deprivation (OGD)-injured cardiomyocytes were performed. Mice with overexpression of omentin1 were constructed by a fat-specific adeno-associated virus (AAV) vector system.

Results

We demonstrated that circulating omentin1 level diminished in HF patients compared with healthy subjects. Furthermore, the fat-specific overexpression of omentin1 ameliorated cardiac function, cardiac hypertrophy, infarct size and cardiac pathological features, and also enhanced SIRT3/FOXO3a signaling in HF mice. Additionally, administration with AAV-omentin1 increased mitochondrial fusion and decreased mitochondrial fission in HF mice, as evidenced by up-regulated expression of Mfn2 and OPA1, and downregulation of p-Drp1(Ser616). Then, it also promoted PINK1/Parkin-dependent mitophagy. Simultaneously, treatment with recombinant omentin1 strengthened OGD-injured cardiomyocyte viability, restrained LDH release, and enhanced the mitochondrial accumulation of SIRT3 and nucleus transduction of FOXO3a. Besides, omentin1 also ameliorated unbalanced mitochondrial fusion-fission dynamics and activated mitophagy, thereby, improving the damaged mitochondria morphology and controlling mitochondrial quality in OGD-injured cardiomyocytes. Interestingly, SIRT3 played an important role in the improvement effects of omentin1 on mitochondrial function, unbalanced mitochondrial fusion-fission dynamics and mitophagy.

Conclusion

Omentin1 improves MI-induced HF and myocardial injury by maintaining mitochondrial dynamical homeostasis and activating mitophagy via upregulation of SIRT3/FOXO3a signaling. This study provides evidence for further application of omentin1 in cardiovascular diseases from the perspective of crosstalk between heart and adipose tissue.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03642-x.

Omentin-1: A newly discovered warrior against metabolic related diseases

INTRODUCTION

: Chronic metabolism-related diseases are challenging clinical problems. Omentin-1 is mainly expressed in stromal vascular cells of adipose tissue and can also be expressed in airway goblet cells, mesothelial cells, and vascular cells. Omentin-1 has been found to exert important anti-inflammatory, antioxidative and anti-apoptotic roles and to regulate endothelial dysfunction. Moreover, omentin-1 also has protective effects against cancer, atherosclerosis, type 2 diabetes mellitus, and bone metabolic diseases. The current review will discuss the therapeutic potential of omentin-1.

AREAS COVERED

: This review summarizes the biological actions of omentin-1 and provides an overview of omentin-1 in metabolic-related diseases. The relevant literature was derived from a PubMed search spanning 1998-2021 using these search terms: omentin-1, atherosclerosis, diabetes mellitus, bone, cancer, inflammation, and oxidative stress.

EXPERT OPINION

: As a novel adipocytokine, omentin-1 is a promising therapeutic target in metabolic-related diseases. Preclinical animal studies have shown encouraging results. Moreover, circulating omentin-1 has excellent potential as a noninvasive biomarker. In the future, strategies for regulating omentin-1 need to be investigated further in clinical trials in a large cohort.

The Roles and Associated Mechanisms of Adipokines in Development of Metabolic Syndrome

Metabolic syndrome is a cluster of metabolic indicators that increase the risk of diabetes and cardiovascular diseases. Visceral obesity and factors derived from altered adipose tissue, adipokines, play critical roles in the development of metabolic syndrome. Although the adipokines leptin and adiponectin improve insulin sensitivity, others contribute to the development of glucose intolerance, including visfatin, fetuin-A, resistin, and plasminogen activator inhibitor-1 (PAI-1). Leptin and adiponectin increase fatty acid oxidation, prevent foam cell formation, and improve lipid metabolism, while visfatin, fetuin-A, PAI-1, and resistin have pro-atherogenic properties. In this review, we briefly summarize the role of various adipokines in the development of metabolic syndrome, focusing on glucose homeostasis and lipid metabolism.

Endogenous Protective Factors and Potential Therapeutic Agents for Diabetes-Associated Atherosclerosis

The complications of macrovascular atherosclerosis are the leading cause of disability and mortality in patients with diabetes. It is generally believed that the pathogenesis of diabetic vascular complications is initiated by the imbalance between injury and endogenous protective factors. Multiple endogenous protective factors secreted by endothelium, liver, skeletal muscle and other tissues are recognized of their importance in combating injury factors and maintaining the homeostasis of vasculatures in diabetes. Among them, glucagon-like peptide-1 based drugs were clinically proven to be effective and recommended as the first-line medicine for the treatment of type 2 diabetic patients with high risks or established arteriosclerotic cardiovascular disease (CVD). Some molecules such as irisin and lipoxins have recently been perceived as new protective factors on diabetic atherosclerosis, while the protective role of HDL has been reinterpreted since the failure of several clinical trials to raise HDL therapy on cardiovascular events. The current review aims to summarize systemic endogenous protective factors for diabetes-associated atherosclerosis and discuss their mechanisms and potential therapeutic strategy or their analogues. In particular, we focus on the existing barriers or obstacles that need to be overcome in developing new therapeutic approaches for macrovascular complications of diabetes.

Omentin Is Independently Associated with Stroke Severity and Ipsilateral Carotid Artery Stenosis in Patients with Acute Cerebral Ischemia

Mounting evidence indicates an association between adipokines and inflammation-related atherosclerosis. Here, we sought to investigate the association of vaspin and omentin with clinical characteristics and outcomes of patients with acute cerebral ischemia (ACI). Consecutive ACI patients were evaluated within 24 h from symptom-onset. Stroke aetiology was classified using TOAST criteria. Adipokines were assayed using quantikine enzyme immunoassay commercially available kits. Stroke severity was assessed by NIHSS-score, and ipsilateral carotid stenosis (≥50% by NASCET criteria) by ultrasound and CT/MR angiography. Major cerebrovascular events were assessed at three months. We included 135 ACI patients (05 (78%) and 30 (22%) with acute ischemic stroke and transient ischemic attack, respectively; mean age ± SD: 59 ± 10 years; 68% men; median NIHSS-score: 3 (IQR:1–7)). Omentin was strongly correlated to admission stroke severity (Spearman rho coefficient: +0.303; p < 0.001). Patients with ipsilateral carotid stenosis had higher omentin levels compared to patients without stenosis (13.3 ± 8.9 ng/mL vs. 9.5 ± 5.5 ng/mL, p = 0.014). Increasing omentin levels were independently associated with higher stroke severity (linear regression coefficient = 0.290; 95%CI: 0.063–0.516; p = 0.002) and ipsilateral carotid stenosis (linear regression coefficient = 3.411; 95%CI: 0.194–6.628; p = 0.038). No association of vaspin with clinical characteristics and outcomes was found. Circulating omentin may represent a biomarker for the presence of atherosclerotic plaque, associated with higher stroke severity in ACI patients.

Inter-Organ Crosstalk in the Development of Obesity-Associated Insulin Resistance

The epidemics of obesity and type 2 diabetes have led to intensive investigation of the underlying mechanisms of these diseases and their main complications such as cardiovascular diseases and non-alcoholic fatty liver disease. This search has contributed to better understand how organs and tissues communicate with each other in the so-called inter-organ crosstalk. Adipose tissue, the liver, or skeletal muscle can actively release secreted factors termed "organokines" which can interact with other distant targets in complex networks. More recently, other novel mediators of inter-organ crosstalk such as extracellular vesicles and their non-traditional cargoes as miRNAs and lncRNAs are gaining importance and represent potential therapeutic targets. In the present chapter we summarize some of the current knowledge on inter-organ communication with a focus on adipose tissue-released factors and their modulation on other organs and tissues like pancreas, liver, skeletal muscle, the cardiovascular system, and the gut in the context of obesity and its progression to insulin resistance. We also provide a perspective on mediators of inter-organ crosstalk as potential therapeutic targets.

The impact of omentin-1 gene polymorphisms (rs2274907 and rs2274908) on serum lipid concentrations and coronary artery disease in a sample of Iraqi individuals (A pilot study)

BACKGROUND

Coronary artery disease (CAD) is the primary cause of death worldwide. It is mainly caused by atherosclerosis that initiates from a genetic-environmental interaction. Studies highlighted the association of numerous gene polymorphisms with CAD. Omentin-1 is secreted from visceral adipose tissues, intestine, and others; it has anti-inflammatory and insulin sensitivity improving roles.

AIM

To explore the association of the omentin-1 gene polymorphisms (rs2274907 and rs2274908) with serum lipid concentrations and CAD in a sample of the Iraqi population.

METHODS

A case-control study was followed, in which CAD patients were analyzed versus a group of healthy persons. Serum lipid concentrations were measured by enzymatic methods. Genotyping of the omentin-1 gene for rs2274907 SNP was achieved by ARMS-PCR, while for rs2274908 SNP by allele-specific PCR (AS-PCR) techniques.

RESULTS

Atherogenic serum lipid concentrations increased significantly in CAD patients relative to the control group. Genotyping of the omentin-1 gene for rs2274907 SNP revealed a significant (OR = 4.11, P = 0.035) elevation of the AT genotype carriers in CAD versus the control groups. The genotype analysis of the rs2274908 SNP failed to exhibit a significant variation. The two analyzed SNPs were indicated to be in linkage disequilibrium (r = 0.772, P < 0.0001). The global haplotype association of the 2 SNPs was demonstrated to be significant (P = 0.006). Serum lipid concentrations were found to be independent of the genotype distribution of the rs2274907 SNP.

CONCLUSION

Carriers of the AT genotype of rs2274907 SNP in the omentin-1gene may have a four-fold risk of developing CAD compared to those of the wild genotype. Alterations of serum lipid concentrations may do not depend on the genotypes of this SNP.

Circulating adiponectin mediates the association between omentin gene polymorphism and cardiometabolic health in Asian Indians

BACKGROUND

Plasma omentin levels have been shown to be associated with circulating adiponectin concentrations and cardiometabolic disease-related outcomes. In this study, we aim to examine the association of omentin gene polymorphism with serum adiponectin levels and cardiometabolic health status using a genetic approach, and investigate whether these associations are modified by lifestyle factors.

METHODS

The study included 945 normal glucose tolerant and 941 unrelated individuals with type 2 diabetes randomly selected from the Chennai Urban Rural Epidemiology Study (CURES), in southern India. Study participants were classified into cardiometabolically healthy and unhealthy, where cardiometabolically healthy were those without hypertension, diabetes, and dyslipidemia. Fasting serum adiponectin levels were measured by radioimmunoassay. The omentin A326T (rs2274907) single nucleotide polymorphism (SNP) was screened by polymerase chain reaction-restriction fragment length polymorphism and direct sequencing.

RESULTS

The 'A' allele of the omentin SNP was significantly associated with lower adiponectin concentrations after adjusting for age, sex, body mass index (BMI), waist circumference (WC) and cardiometabolic health status (p = 1.90 x 10-47). There was also a significant association between circulating adiponectin concentrations and cardiometabolic health status after adjusting for age, sex, BMI, WC and Omentin SNP (p = 7.47x10-10). However, after adjusting for age, sex, BMI, WC and adiponectin levels, the association of 'A' allele with cardiometabolic health status disappeared (p = 0.79) suggesting that adiponectin serves as a mediator of the association between omentin SNP and cardiometabolic health status. There were no significant interactions between the SNP and dietary factors on adiponectin levels and cardiometabolic health status (p>0.25, for all comparisons).

CONCLUSIONS

Our findings show that adiponectin might function as a mechanistic link between omentin SNP and increased risk of cardiometabolic diseases independent of common and central obesity in Asian Indians. Before strategies to promote adiponectin modulation could be implemented, further studies are required to confirm the molecular mechanisms involved in this triangular relationship between omentin gene, adiponectin and cardiometabolic diseases.

Does Dietary Intake Impact Omentin Gene Expression and Plasma Concentration? A Systematic Review

BACKGROUND

Omentin is an adipokine with anti-inflammatory and insulin-sensitizing effects that can play a protective role against cardiovascular disease and diabetes. The aim was to systematically review and summarize the existing evidence on the association between overall dietary intake and omentin gene expression and circulation.

SUMMARY

A literature search was conducted in PubMed, Scopus, and Web of Science up to September 2019. Of the 1,940 retrieved articles, 20 relevant studies were included, 6 of which were observational, 11 were clinical trials in humans, and 3 were animal studies. Four randomized controlled trials (RCTs) had a high risk of bias (RoB), 1 had "some concerns", and 2 had a low RoB. Among the nonrandomized studies with comparators, 4 had a serious RoB and 2 had a moderate RoB. In the experimental animal studies with a moderate RoB, conflicting results for omentin serum concentration were found for high-fat and low-fat diets. A high-fat diet (HFD) was shown to reduce omentin gene expression in one animal study. In the observational studies, omentin serum concentration was reduced by Ramadan fasting and saturated fatty acid (SFA) intake, and an increase in omentin gene expression was observed with monounsaturated fatty acid (MUFA) intake. There was no association of dietary inflammatory index (DII), macronutrient intake, or total calorie intake with omentin plasma concentrations. In the human interventional studies, omentin plasma concentration increased with a long-term low-calorie, low-fat diet (LFD), and no change was seen with a HFD or a short-term low-calorie diet (LCD). Key Messages: It seems that a long-term diet with a lower fat content and a balanced distribution of fatty acids, i.e., a higher MUFA and lower SFA intake, may effectively increase omentin plasma concentration, possibly via improved insulin resistance and reduced inflammation, but more research is needed to confirm or refute this.

Association of Circulating Omentin-1 with Osteoporosis in a Chinese Type 2 Diabetic Population

Aims

Omentin-1, a newly identified adipokine, has been demonstrated to be associated with bone metabolism, but the results have been inconsistent. Moreover, the potential relationship of circulating omentin-1 with diabetic osteoporosis has never been reported. This study is intended for studying the association between circulating omentin-1, bone mineral density (BMD), prior fragility fractures, and other bone metabolic-related parameters.

Methods

Circulating omentin-1 levels were measured in 172 patients with type 2 diabetes mellitus (T2DM), and participants were divided into the normal BMD group (n = 52), the osteopenia group (n = 66), and the osteoporosis group (n = 54). The relationship between circulating omentin-1 and diabetic osteoporosis and other parameters was analyzed.

Results

Circulating omentin-1 was significantly higher in the osteoporosis group than in the normal group and in the osteopenia group (both P < 0.05). Circulating omentin-1 levels were correlated significantly and positively with sex; high-density lipoprotein cholesterol; apolipoprotein A; and prevalence of prior fragility fractures, diabetic nephropathy, and retinopathy; they were correlated negatively with diastolic blood pressure, triglyceride, hemoglobin, atherogenic index of plasma, osteoporosis self-assessment tool for Asians, BMD at different skeletal sites, and corresponding T scores, irrespective of age, sex, and body mass index (P < 0.01 or P < 0.05). Moreover, circulating omentin-1 was an independent decisive factor for the presence of osteoporosis only in women after multivariate adjustment (odds ratio: 1.069; 95% confidence interval: 1.003-1.139; P < 0.05). Lastly, the analysis of receiver operating characteristic curves revealed that the best cutoff value for circulating omentin-1 to predict diabetic osteoporosis was 15.37 ng/mL (sensitivity: 71.7%; specificity: 58.5%) in female subjects.

Conclusions

High levels of circulating omentin-1 may be associated with the development of osteoporosis in female diabetic subjects and may be a potential biomarker for diabetic osteoporosis in women.

Cardiovascular autonomic neuropathy in patients with type 2 diabetes mellitus and its association with serum omentin and leptin

Cardiovascular autonomic neuropathy (CAN) is a major cause of morbidity and mortality in patients with diabetes as it is associated with a high risk of cardiac arrhythmias.

Newly Discovered Adipokines: Pathophysiological Link Between Obesity and Cardiometabolic Disorders

With the increasing prevalence of obesity, obesity-related problems such as cardiometabolic disorders (CMD), are also rapidly increasing. To prevent and alleviate the progressive course of CMD, it is important to discover the pathophysiological mechanisms between obesity and CMD. Adipose tissue is now recognized as an active endocrine organ that releases adipokines. Adipokines play a pivotal role in chronic low-grade inflammation, oxidative stress, and impaired insulin signaling, contributing to metabolic derangement and leading to CMD. Recent studies have provided substantial evidence supporting the association between adipokines and CMD. In this review, we highlight the pathophysiological action of adipokines in CMD that includes metabolic syndrome, type 2 diabetes, non-alcoholic fatty liver disease, and cardiovascular diseases. We focused on translational and clinical research of novel adipokines associated with metabolic and cardiovascular regulation. Exploration of the role of these adipokines connecting obesity and CMD may provide a perspective on adipokine-based therapeutic implications for CMD.

Genetic variation, adipokines, and cardiometabolic disease

Adipokines are adipocyte-secreted cell signalling proteins that travel to distant target organs and tissues, where they regulate a variety of biological actions implicated in cardiometabolic health. In the past decade, genome-wide association studies have identified multiple genetic variants associated with circulating levels of adipokines, providing new instruments for examining the role of adipokines in cardiometabolic pathologies. Currently, there is limited genetic evidence of causal relationships between adipokines and cardiometabolic disease, which is consistent with findings from randomized clinical trials that have thus far shown limited success for adipokine-based treatments in improving cardiometabolic health. Incorporating human genetic data in early phases of target selection is essential for enhancing the success of adipokine-based therapies for cardiometabolic disease.

Serum Omentin Levels in Patients with Prostate Cancer and Associations with Sex Steroids and Metabolic Syndrome

Mechanisms linking obesity and prostate cancer (PC) include increased insulin signaling, persistent inflammation, and altered adipocytokines secretion. Previous studies indicated that omentin may play a potential role in cancerogenesis of different sites, including the prostate. In this study, we focused on the hormonal and metabolic characteristics of men recruited for prostate biopsy. We evaluated serum concentrations of adipocytokines and sex steroids where concentrations are related to the adiposity: omentin, leptin, testosterone, estradiol, and sex hormone-binding globulin (SHBG). Aim: The aim of the study was to assess the concentration of serum omentin in men with PC. We also investigated relationships between omentin, leptin, sex steroids, SHBG, age, and metabolic syndrome (MS). Methods: Our study was conducted on 72 patients with PC and 65 men with benign prostate hyperplasia (BPH). Both groups were compared for body mass index. Results: Comparing men with PC to subjects with BPH there were significantly higher serum concentrations of omentin, estradiol, and prostate specific antigen (PSA) in the former. Estradiol/testosterone ratio, which is a marker of testosterone to estradiol conversion, was also significantly higher in the PC group. MS was diagnosed in 47 men with PC and in 30 men with BPH, the prevalence was significantly higher in the PC group. When the subjects with PC were subdivided into two subgroups, the serum omentin did not differ between those with MS and without MS. In the overall sample serum, omentin was positively associated with age, SHBG, and leptin. A positive correlation was also found between omentin and estradiol/testosterone ratio, and negatively with testosterone/SHBG ratio. Positive correlations were noted between age and SHBG, PSA and estradiol/testosterone ratio. In our study, a drop of total testosterone and testosterone/SHBG ratio, due to age, was also demonstrated. Conclusions: In patients with prostate cancer, serum omentin may be a diagnostic indicator. Omentin levels do not correlate with estradiol or testosterone concentrations but they are related to the testosterone/SHBG ratio. Omentin is not associated with an increased likelihood of having metabolic syndrome in men with prostate cancer.

The Role of Secretory Activity Molecules of Visceral Adipocytes in Abdominal Obesity in the Development of Cardiovascular Disease: A Review

Adipose tissue is considered one of the endocrine organs in the body because of its ability to synthesize and release a large number of hormones, cytokines, and growth and vasoactive factors that influence a variety of physiological and pathophysiological processes, such as vascular tone, inflammation, vascular smooth muscle cell migration, endothelial function, and vascular redox state. Moreover, genetic factors substantially contribute to the risk of obesity. Research into the biochemical effects of molecules secreted by visceral adipocytes as well as their molecular genetic characteristics is actively conducted around the world mostly in relation to pathologies of the cardiovascular system, metabolic syndrome, and diabetes mellitus. Adipokines could be developed into biomarkers for diagnosis, prognosis, and therapeutic targets in different diseases. This review describes the relevance of secretory activity molecules of visceral adipocytes in cardiovascular disease associated abdominal obesity.