Changes of serum omentin levels and relationship between omentin and adiponectin concentrations in type 2 diabetes mellitus

Effect of Exercise Training on Some Anti-Inflammatory Adipokines, High Sensitivity C-Reactive Protein, and Clinical Outcomes in Sedentary Adults With Metabolic Syndrome

OBJECTIVE

This study aimed to investigate the effects of aerobic interval training and resistance training on anti-inflammatory adipokines, high sensitivity C-reactive protein, and clinical outcomes in sedentary men with metabolic syndrome.

METHODS

A total of 33 sedentary men with metabolic syndrome (age: 46.2 ± 4.6 years; body mass index: 35.4 ± 1.9 kg.m2) were randomly assigned to one of 3 groups: aerobic interval training (n = 12), resistance training (n = 10), or control (n = 11). Participants in the exercise groups completed a 12-week training program, 3 sessions per week, while those in the control group maintained their sedentary lifestyle. The levels of high sensitivity C-reactive protein (hs-CRP), omentin-1, adiponectin, lipid profiles, blood pressure, glucose metabolism, body composition, and peak oxygen uptake (VO2peak) were measured at baseline and after the intervention.

RESULTS

Both aerobic interval training and resistance training significantly improved the levels of omentin-1 and adiponectin, as well as reduced inflammation, as indicated by a decrease in hs-CRP levels. Exercise training also led to significant improvements in lipid profiles, blood pressure, glucose metabolism, and body composition. Specifically, the aerobic interval training group had significantly greater increases in high-density lipoprotein cholesterol and VO2peak, as well as greater reductions in low-density lipoprotein cholesterol, triglycerides, and total cholesterol compared to the resistance training group.

CONCLUSION

Exercise training, particularly aerobic interval training and resistance training, can be an effective non-pharmacological intervention for managing inflammation and improving cardiovascular health in metabolic syndrome patients.

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.

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.

Aerobic Exercise Training Effects on Omentin-1, Insulin Resistance, and Lipid Profile Among Male Smokers

Background: Omentin-1 is a circulating adipokine that can serve as a biomarker for assessment of metabolic risk factors. We investigated the effect of eight weeks of aerobic exercise training on serum omentin-1, insulin resistance and lipid profile in nonsmokers and smokers. Methods: Nineteen male nonsmokers (aged 27.88 ± 2.47 years, and with BMI of 22.69 ± 1.77 kg.m-2) and twenty male smokers (aged 30.11 ± 1.96 years, and with BMI of 23.12 ± 1.91 kg.m-2) were randomly assigned into nonsmokers control group (C), nonsmokers exercise group (E), control smoker group (CS), and exercise smoker group (ES). Exercise groups participated in an eight-week aerobic exercise training program (three times a week, 20-35 min per session at 55%-70% of maximum heart rate). Serum omentin-1 and insulin values were determined by ELISA. The Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), glucose level and lipid profile were measured before and after the intervention. Pearson correlation test, Eta test, paired samples t-test, one and two-way analysis of variance (ANOVA) and post-hoc Tukey test were applied for data analysis (p < .05). Results: Aerobic exercise improved both serum omentin-1 and high lipoprotein cholesterol (HDL-C) in the exercise groups (P < .05). Also, exercise training reduced insulin, glucose, HOMA-IR, triglyceride (TG), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels (p < .05). Omentin-1 was significantly correlated with glucose, insulin, HOMA-IR, TG, TC, LDL-C and HDL-C in both nonsmokers and smokers. Conclusions: The findings suggest that aerobic exercise-induced changes in omentin-1 in the exercise-trained groups may be associated with the beneficial effects of exercise on reduced insulin resistance and lipid profile.

The Interplay of Lifestyle and Adipokines in the Non-Obese Stroke-Prone Spontaneously Hypertensive Rats

Although the morphological features and functions of adipose tissue are well-described in obesity-prone animal models, less information is available on animals such as the stroke-prone spontaneously hypertensive (SHRSP) strain with cardiovascular abnormalities, which is not characterized by excessive adiposity. Our aim was to focus on lifestyle-induced (type of diet and physical exercise) effects on adipokine profile and lipid peroxidation in SHRSP rats. In our study, male Wistar-kyoto (control) and SHRSP rats were used. SHRSP rats were fed either standard chow or a high-fat diet with 40% fat content (HFD). One group of the animals was placed into cages fitted with a running-wheel; thus, the dietary and training period started at the same time and lasted for 12 weeks. At the end of the experimental period, adiponectin, leptin, omentin, and chemerin concentrations were determined from adipose tissue and serum. Besides adipokines, malondialdehyde (MDA) levels were also measured. Twelve weeks of HFD significantly decreased adiponectin and omentin concentrations of both adipose tissue and serum, which were ameliorated by physical exercise. Serum leptin, chemerin, and MDA values were elevated in HFD groups; however, physical exercise was able to mitigate these adverse changes. Our results underpin the crosstalk between lifestyle changes and dysfunctional adipose tissue in SHRSP rats.

Impact of Two Types of Exercise Interventions on Leptin and Omentin Concentrations and Indicators of Lipid and Carbohydrate Metabolism in Males with Metabolic Syndrome

Leptin (LEP) and omentin (OMEN) are proteins whose concentrations change with the development of the metabolic syndrome (MetS). There are few intervention studies using various forms of physical activity in people with MetS that aim to determine the impact of physical exercise on the fluctuations of the presented hormones, and their results are contradictory. The present study aimed to examine the effect of two types of exercise intervention on LEP and OMEN concentrations and indicators of lipid and carbohydrate metabolism in males with MetS. The study included 62 males with MetS (age 36.6 ± 6.9 years, body mass 110.31 ± 17.37 kg), randomly allocated to EG1, the examined group with aerobic training (n = 21); EG2, the examined group with combined aerobic and resistance training (n = 21), both for 12 weeks, and the control group (CG) without interventions (n = 20). Anthropometric measurements, body composition (body fat [BF], android body fat [ANDR]), as well as a biochemical blood analysis (omentin [OMEN], leptin [LEP], quantitative insulin sensitivity check index [QUICKI], high-density lipoprotein cholesterol [HDL-C] and nonHDL-C) were performed at baseline, and at 6 and 12 weeks of interventions and after 4 weeks after ending intervention (follow-up). Intergroup and intragroup comparisons were performed. In the intervention groups EG1 and EG2, a decrease in BF was observed as well as an improvement in carbohydrate metabolism parameters. In the EG1 group, the level of ANDR was reduced. In EG2 a decrease in LEP concentration between measurements was confirmed. However, no significant changes were found in the concentration of OMEN in any groups. Combined aerobic and resistance exercises led to a higher reduction of LEP concentration than applying only aerobic training in males with MetS.

Exogenous glutamine ameliorates diabetic nephropathy in a rat model of type 2 diabetes mellitus through its antioxidant and anti-inflammatory activities

This study aimed to evaluate the effects of glutamine (Gln) on diabetic nephropathy and other complications in a rat model of type 2 diabetes mellitus. Streptozotocin/nicotinamide induced diabetic rats were enrolled as an animal model of type 2 diabetes mellitus. Animals were divided into control, diabetic, and Gln (1000 mg/l in drinking water, eight weeks) treated diabetic groups. Gln alleviated renal inflammatory and oxidative stress biomarkers (tumour necrosis factor-alpha, interleukin 6, glutathione peroxidase, total superoxide dismutase, and glutathione), decreased serum uric acid and creatinine, and restored renal histopathological changes (glomerular volume, sclerosis, and leukocyte infiltration). Additionally, Gln ameliorated other complications, including systemic oxidative stress (serum malondialdehyde and nitric oxide, serum and liver glutathione, glutathione peroxidase, and total superoxide dismutase, and liver catalase), insulin resistance, hyperglycaemia, and hyperlipidaemia. Collectively, Gln attenuates diabetic nephropathy and other complications in type 2 diabetes mellitus in rats through its antioxidant and anti-inflammatory activities.

Adipokines from white adipose tissue in regulation of whole body energy homeostasis

Diseases originating from altered energy homeostasis including obesity, and type 2 diabetes are rapidly increasing worldwide. Research in the last few decades on animal models and humans demonstrates that the white adipose tissue (WAT) is critical for energy balance and more than just an energy storage site. WAT orchestrates the whole-body metabolism through inter-organ crosstalk primarily mediated by cytokines named "Adipokines". The adipokines influence metabolism and fuel selection of the skeletal muscle and liver thereby fine-tuning the load on WAT itself in physiological conditions like starvation, exercise and cold. In addition, adipokine secretion is influenced by various pathological conditions like obesity, inflammation and diabetes. In this review, we have surveyed the current state of knowledge on important adipokines and their significance in regulating energy balance and metabolic diseases. Furthermore, we have summarized the interplay of pro-inflammatory and anti-inflammatory adipokines in the modulation of pathological conditions.

Evaluation of serum adipokines (omentin-1 and visfatin) in coronary artery disease at a North Indian hospital

Objective. Adipose tissue is considered to be an endocrine organ that secretes bioactive substances known as adipokines that contribute to the pathophysiology of metabolic and coronary diseases related to obesity. In this study, various novel biomarkers, such as inflammatory markers that are pro-inflammatory (visfatin) and anti-inflammatory (omentin-1), as prognostic indicators for people with coronary artery disease (CAD) were investigated. Methods. In this study, 30 diabetic patients with CAD, 30 diabetic patients without CAD, and 30 healthy control counterparts were included. Serum omentin and visfatin concentrations were evaluated by solid-phase enzyme linked immunosorbent assay (ELISA) kit. Patients with established diagnosis of CAD based on angiography, ECG, and elevated cardiac marker level were included into the study. Patients with cardioembolic stroke, cerebral venous sinus thrombosis, CNS vasculitis, and hemorrhage due to trauma, tumor, vascular malformation, and coagulopathy were excluded. Results. The serum omentin-1 levels were significantly higher in the healthy controls in comparison with the diabetic group (p<0.0001) and serum visfatin levels were significantly higher in the diabetic group in comparison with the healthy controls (p<0.0001). The serum omentin levels were significantly higher in the diabetic group in comparison with the cardio-diabetic group (p<0.0001) and serum visfatin levels were significantly higher in the cardio-diabetic group in comparison with the diabetic group (p<0.0001). The serum omentin-1 showed negative correlation with the serum visfatin in the cardio-diabetic group. Conclusion. The adipokines, such as omentin and visfatin, may be good therapeutic candidates in preventing or ameliorating CAD.

A Physiological Approach to Inflammatory Markers in Obesity

Obesity is one of the most critical health problems all over the world; it is associated with metabolic dysfunction and overnutrition. Changes in the physiological function of adipose tissue, leading to altered secretion of adipocytokines, inflammatory mediators release, and chronic low-grade inflammation, are seen in obesity. Macrophages, neutrophils, CD4+ and CD8+ T cells, B cells, natural killer T (NKT) cells, eosinophils, mast cells, and adipocytes are involved in the inflammatory response that occurs during obesity. Various inflammatory markers are released from these cells. In this chapter, we will mention inflammatory mechanisms and markers of obesity.

Thromboinflammatory Processes at the Nexus of Metabolic Dysfunction and Prostate Cancer: The Emerging Role of Periprostatic Adipose Tissue

Simple Summary

As overweight and obesity increase among the population worldwide, a parallel increase in the number of individuals diagnosed with prostate cancer was observed. There appears to be a relationship between both diseases where the increase in the mass of fat tissue can lead to inflammation. Such a state of inflammation could produce many factors that increase the aggressiveness of prostate cancer, especially if this inflammation occurred in the fat stores adjacent to the prostate. Another important observation that links obesity, fat tissue inflammation, and prostate cancer is the increased production of blood clotting factors. In this article, we attempt to explain the role of these latter factors in the effect of increased body weight on the progression of prostate cancer and propose new ways of treatment that act by affecting how these clotting factors work.

Abstract

The increased global prevalence of metabolic disorders including obesity, insulin resistance, metabolic syndrome and diabetes is mirrored by an increased incidence of prostate cancer (PCa). Ample evidence suggests that these metabolic disorders, being characterized by adipose tissue (AT) expansion and inflammation, not only present as risk factors for the development of PCa, but also drive its increased aggressiveness, enhanced progression, and metastasis. Despite the emerging molecular mechanisms linking AT dysfunction to the various hallmarks of PCa, thromboinflammatory processes implicated in the crosstalk between these diseases have not been thoroughly investigated. This is of particular importance as both diseases present states of hypercoagulability. Accumulating evidence implicates tissue factor, thrombin, and active factor X as well as other players of the coagulation cascade in the pathophysiological processes driving cancer development and progression. In this regard, it becomes pivotal to elucidate the thromboinflammatory processes occurring in the periprostatic adipose tissue (PPAT), a fundamental microenvironmental niche of the prostate. Here, we highlight key findings linking thromboinflammation and the pleiotropic effects of coagulation factors and their inhibitors in metabolic diseases, PCa, and their crosstalk. We also propose several novel therapeutic targets and therapeutic interventions possibly modulating the interaction between these pathological states.

Exercise training modulates adipokines dysregulations in metabolic syndrome

Metabolic syndrome (MetS) is a cluster of risk factors for various metabolic diseases, and it is characterized by central obesity, dyslipidemia, hypertension, and insulin resistance. The core component for MetS is adipose tissue, which releases adipokines and influences physical health. Adipokines consist of pro and anti-inflammatory cytokines and contribute to various physiological functions. Generally, a sedentary lifestyle promotes fat accumulation and secretion of pro-inflammatory adipokines. However, regular exercise has been known to exert various beneficial effects on metabolic and cognitive disorders. Although the mechanisms underlying exercise beneficial effects in MetS are not fully understood, changes in energy expenditure, fat accumulation, circulatory level of myokines, and adipokines might be involved. This review article focuses on some of the selected adipokines in MetS, and their responses to exercise training considering possible mechanisms.

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Adipokines are a potential link between visceral fats and complications of MetS.

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Physical inactivity increases pro-inflammatory adipokines.

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Moderate aerobic exercise increases anti-inflammatory adipokines partly via reducing adipose tissue mass.

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Physical exercise-induced myokines might mediate beneficial effects via a cross-talk with adipose tissues.

Correlation of Serum Vaspin, Omentin-1, and adiponectin with metabolic phenotypes in Type-2 diabetes mellitus patients

Objectives:

To investigate adipocytokines’ (vaspin, omentin-1, and adiponectin) correlation with metabolic phenotypes in type 2 diabetes mellitus (T2DM) patients.

Methods:

This case-control research was done at the Diabetic Clinic in Jeddah, Kingdom of Saudi Arabia (KSA), from November 2018 to March 2019. Seventy-five T2DM patients and 75 gender, age, and BMI-matched healthy subjects were recruited for this research.

Results:

In DM patients, the concentrations of serum vaspin and omentin-1 were substantially lower (p<0.001) than in the control group. A significant positive relationship between vaspin concentration and DBP (p<0.001), BMI (p<0.001), and waist circumference (p<0.001) was found in patients and control subjects, while FPG (p<0.016), serum insulin (p<0.001), HOMA-IR (p<0.001), TC (p<0.001), TG (p<0.001), and LDLc (p<0.001) were significantly interrelated among patients. Serum concentrations of omentin-1 and ADN were significantly negatively correlated with serum insulin, HOMA-IR, and TG among the DM group. Serum vaspin and ADN levels were significantly higher in the cases and control groups with BMI>25, and no gender-wise variance was observed in adipocytokines levels. Binary logistic regression analysis showed a significantly negative predictive relationship of vaspin and omentin-1 with DM.

Conclusion:

The DM group displayed substantially lower serum vaspin and omentin-1 levels. However, there was no consistent relationship observed between these adipocytokines and metabolic phenotypes.

Relationship between circulating serum omentin-1 levels and nascent metabolic syndrome in patients with hypertension

The prevalence of metabolic syndrome (MetS) is more common in patients with hypertension and is associated with an increased risk of target organ damage and/or cardiovascular disease (CVD). Omentin-1 is a beneficial adipokine considered to play a role in MetS and MetS-related states such as obesity, diabetes, and coronary artery disease. The aim of this study was to determine the relationship between circulating omentin-1 levels and MetS uncomplicated by diabetes or CVD (nascent MetS) in patients with hypertension. In this study, 110 patients (54 men, 49%; average age: 49.72±11.32 years) treated for hypertension but without overt diabetes and/or CVD were enrolled. 66 patients were stratified into MetS (+) (group 1) and 44 patients into MetS (-) (group 2) according to the American Heart Association/National Heart, Lung, and Blood Institute criteria. The triglyceride glucose (TyG) index was used to assess insulin resistance. Circulating omentin-1 levels in venous blood samples were measured by an ELISA kit. Circulating omentin-1 levels in patients with MetS were significantly lower than in patients without MetS (46.35 ng/mL (42.70-57.70 ng/mL) vs 130.95 ng/mL (62.83-236.48 ng/mL), p<0.001). Omentin-1 was inversely correlated with TyG index (r=-0.204, p=0.033). In a multivariate logistic regression analysis, omentin-1, TyG index, and body mass index were independent predictors of MetS. A receiver operating characteristic curve analysis determined that the best cut-off value for omentin-1 in predicting MetS was 62.20 ng/mL and the area under the curve was 0.880 (95% CI 0.817 to 0.942, p<0.001). The findings of this study suggest that circulating omentin-1 levels are inversely related to the presence of MetS and may be a reliable marker to predict the development of MetS in patients with hypertension.

Association of Plasma Omentin-1 Levels With Diabetes and Its Complications

Introduction: Plasma omentin-1 is a relatively new biomarker that has anti-diabetogenic and its level is inversely related with insulin resistance and diabetes mellitus, thus, increasing the risk of diabetic complications. In this study, we will determine the association between serum plasma omentin-1 levels and diabetes and its complications.

Methods: This case control study was conducted from July 2020 to August 2021 in the internal medicine unit of a tertiary care hospital in Pakistan. There was a total of three groups, each comprising 250 patients. One group was type 2 diabetic patients with complications, the second group was type 2 diabetic patients without complications, and the third group was the control group, i.e. participants without type 2 diabetes. Their plasma omentin-1 levels were compared.

Results: Patients with diabetic complications had significantly lower serum omentin levels than patients without complications (59.01 ± 9.21 ug/dL vs. 75.72 ± 14.11 ug/L; p-value: <0.0001). Patients with diabetes had significantly lower serum omentin levels in comparison to patients without diabetes (75.72 ± 14.11 ug/dL vs. 90.12 ± 17.89 ug/L; p-value: <0.0001).

Conclusion: Based on our study, plasma omentin-1 is negatively associated with diabetes and its complications. Therefore, adequate levels of omentin-1 are needed in order to prevent diabetic complications.

Changes of omentin-1 and chemerin during 4 weeks of lifestyle intervention and 1 year follow-up in children with obesity

AIMS

Data about the influence of short-term lifestyle intervention in children with obesity on long-term follow-up body weight, adipokines and cardiometabolic risk parameters is scarce.

METHODS

In a subgroup of the LOGIC-trial (Long-term Effects of Lifestyle Intervention in Obesity and Genetic Influence in Children), we assessed anthropometry (BMI, BMI-SDS (Standard Deviation Score), adipokines (omentin-1, chemerin, leptin, adiponectin) and cardiometabolic risk parameters, (e.g. hsCRP) in children with overweight/obesity after 4 weeks of lifestyle intervention (n = 156, 14.0 ± 1.8 yrs) and after one year follow-up (n = 50). Data were compared to normal weight children (JuvenTUM school cohort; n = 152, 13.3 ± 0.7 yrs).

RESULTS

Short-term lifestyle intervention was associated with a significant reduction in BMI and BMI-SDS (p < 0.001), with significant reductions in hsCRP, leptin, and chemerin levels, and an increase in adiponectin and omentin-1 levels (p < 0.001 for all). After one year follow-up a significant reduction in BMI and BMI-SDS was observed in children from the LOGIC-trial (p < 0.001). Improvements in adiponectin (p = 0.025) and chemerin levels (p = 0.027) were seen in children with clear weight loss success (BMI-SDS reduction ≥ 0.2), whereas children with no or only mild weight loss success showed an increase in leptin levels (p < 0.001). An increase in omentin-1 levels was observed after 1 year independent of weight change (p < 0.001).

CONCLUSION

Effects of short-term weight reduction on mean BMI and BMI-SDS persist over one year. Improvements in omentin-1 levels were independent of short-term or long-term weight loss.

TRIAL REGISTRATION

ClinicalTrials.gov: LOGIC-trial: NCT01067157, JuvenTUM-trial: NCT00988754.

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.

Relationships between serum omentin-1 concentration, body composition and physical activity levels in older women

This study aimed to investigate the relationships between omentin-1, body composition and physical activity (PA) levels in older women.Eighty-one older women (age = 64 ± 6years; body mass index = 24.2 ± 3.2 kg/m2; body fat percentage = 36.1 ± 5.7%) participated in this study. We divided the subjects into overweight/obesity and normal weight group. Body composition was measured by dual energy X-ray absorptiometry. Serum omentin-1 concentration was measured using enzyme linked immunosorbent assay. PA levels were obtained by using accelerometers. In addition, anthropometric and insulin resistance values were determined.Omentin-1 level in overweight/obesity group was significantly lower than in the normal weight group (P < .01). Analysis of all subjects showed that serum omentin-1 was negatively correlated with body weight, BMI (body mass index), waist circumference (WC), WHR (waist-to-hip ratio), percentage of body fat, total body fat mass (FM), fat-free mass (FFM) (r = -.571, -0.569, -0.546, -0.382, -0.394, -0.484, -0.524, all P < .01), respectively. We also found a negative correlation between moderate-to-vigorous physical activity (MVPA) and total body FM (r = -.233, P < .05). However, no significant correlation was found between omentin-1 and sedentary behavior and MVPA (both P > .05). Moreover, the relationship between omentin-1, body composition and PA was analyzed by using multiple linear stepwise regressions. The results showed that serum omentin-1 concentration was inversely correlated with total body FM (β = -0.334, P = .004) in multiple linear stepwise regression analysis.We found that total body FM was inversely related to serum omentin-1 concentration and PA levels, but there was no correlation between omentin-1 and PA levels. These results showed that PA may participate in the regulation of body composition, which may be also affected by serum omentin-1. However, the mechanism by which PA affects body composition may not be through omentin-1 and was more likely through other metabolic pathways.

Omentin-1: Protective impact on ischemic stroke via ameliorating atherosclerosis

Omentin-1, a newly identified adipokine, has recently been revealed as a novel biomarker for ischemic stroke (IS). Low circulating omentin-1 levels could indicate a high risk of IS, and elevated omentin-1 levels exert a favorable impact on cerebral ischemia. Furthermore, omentin-1 has anti-atherosclerotic, anti-inflammatory, and cardiovascular protective capabilities through the intracellular Akt/AMP-activated protein kinase (AMPK)/ nuclear factor-κB (NF-κB) and certain protein kinase (ERK, JNK, and p38) signaling pathways. Omentin-1 also alleviates endothelial cell dysfunction, improves revascularization via the Akt-endothelial nitric-oxide synthase (eNOS) regulatory axis, promotes endothelium-dependent vasodilation through endothelium-derived NO in an eNOS fashion, and inhibits VSMC proliferation by means of AMPK/ERK signaling pathways, VSMC migration via inactivation of the NADPH oxidase (NOX)/ROS/p38/HSP27 pathways and artery calcification via the PI3K-Akt pathway. These findings indicate that omentin-1 may be a negative mediator of IS. Pharmacologically, several lines of clinical evidence indicate that metformin and statins could elevate omentin-1 levels, although the specific mechanism has not been precisely delineated until now. This study is the first to summarize the comprehensive mechanisms between omentin-1 and atherosclerosis and to review the shielding effect of omentin-1 on IS. We shed light on omentin-1 as a novel therapeutic target for combating IS.

Role of Omentin in Obesity Paradox in Lung Cancer

Simple Summary

Unlike other cancers, lung cancer risk is inversely associated with body mass index (BMI) with limited mechanistic understanding. Overweight and obese patients have been consistently found to respond better to therapy and show better survival. The adipose tissue—in addition to storing energy—secretes multiple unique cytokines or adipokines. Our in silico analysis reveals that a novel adipokine, omentin, is significantly and consistently downregulated in lung cancers compared to healthy lung tissue. Omentin was also found to be negatively correlated with important oncogenic transcription factors like ELK4, FOXA1 and FOXC1. Our study warrants further mechanistic studies on the role of omentin in lung cancers.

Abstract

Lung cancer remains the second-most-common cancer worldwide and is associated with the highest number of cancer-related mortality. While tobacco smoking is the most important risk factor for lung cancer, many other lifestyles and occupational factors significantly contribute. Obesity is a growing global health concern and contributes to ~30% cancer-related mortality, but unlike other lifestyle diseases, lung cancer is negatively associated with obesity. We meta-analyzed multiple case-control studies confirming increased survival and better outcomes in overweight and obese lung cancer patients. Tumor heterogeneity analysis showed significant enrichment of adipocytes and preadipocytes in normal lungs compared to lung cancers. Interestingly, one of the understudied adipokine, omentin, was significantly and consistently lower in lung neoplasms compared to normal lungs. Omentin has been examined in relation to osteoarthritis, inflammatory bowel disease, cardiovascular diseases, diabetes, chronic liver disease, psoriasis and some other cancers. Aberrant expression of omentin has been reported in solid tumors; however, little is known about its role in lung cancer. We found omentin to be consistently downregulated in lung cancers, and it exhibited a negative correlation with important transcription factors FOXA1, EN1, FOXC1 and ELK4. We, therefore, suggest that omentin may serve as a prognostic factor in lung cancer and explain the “obesity paradox” in lung cancer.

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.

The association between serum omentin level and bodyweight: A systematic review and meta-analysis of observational studies

BACKGROUND AND AIMS

A number of studies have examined the association between omentin and body weight, but the findings have been inconclusive. Here in, we systematically reviewed available observational studies to elucidate the overall relationship between omentin and body weight, by comparison of serum omentin level in overweight/obese and normal weight subjects.

METHODS

PubMed, Science direct, Scopus and ISI web of science databases were searched for all available literature until January 2020 for studies assessing the association between omentin and body weight. The Newcastle-Ottawa Quality Assessment Scale was used to assess the quality of each study.

RESULTS

A total of 27 articles met the inclusion criteria and were included in our systematic review and meta-analysis. There was a significant association between omentin serum level and body weight (Standard Mean Difference (SMD) -0.43; 95% CI, -0.70 to -0.15; P = 0.002; I² = 93.2%). In order to find the probable source of heterogeneity subgroup analysis based on the participants' age (adolescent, adult), gender (male, female, both gender), health status (healthy, unhealthy), geographical location (Asian, non-Asian countries), study quality (low, medium, high), study design (case-control, cross-sectional), participants' health status (healthy, unhealthy) and BMI (obese, overweight) was carried out.

CONCLUSION

According to what was discussed, we found that serum omentin level is significantly lower in overweight subjects but not obese ones. This finding should be interpreted cautiously because of significant heterogeneity among included studies.

Omentin: a biomarker of cardiovascular risk in individuals with axial spondyloarthritis

Cardiovascular (CV) disease is the main cause of mortality in axial spondyloarthritis (axSpA). CV risk is enhanced by dysregulation of adipokines. Low omentin levels were associated with metabolic dysfunction and CV disease in conditions different from axSpA. Accordingly, we evaluated the genetic and functional implication of omentin in CV risk and subclinical atherosclerosis in a cohort of 385 axSpA patients. Subclinical atherosclerosis was evaluated by carotid ultrasound. Omentin rs12409609, in linkage disequilibrium with a polymorphism associated with CV risk, was genotyped in 385 patients and 84 controls. Serum omentin levels were also determined. omentin mRNA expression was assessed in a subgroup of individuals. Serum and mRNA omentin levels were lower in axSpA compared to controls. Low serum omentin levels were related to male sex, obesity, inflammatory bowel disease (IBD) and high atherogenic index. rs12409609 minor allele was associated with low omentin mRNA expression in axSpA. No association was observed with subclinical atherosclerosis at the genetic or functional level. In conclusion, in our study low omentin serum levels were associated with CV risk factors in axSpA. Furthermore, rs12409609 minor allele may be downregulating the expression of omentin. These data support a role of omentin as a CV risk biomarker in axSpA.

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.

Are Omentin Rs2274907 and Vaspin Rs2236242 Gene Polymorphisms Related to Body Composition, Lipid Profile and Other Adipokines in Prepubertal Healthy Children?

Purpose/Aim: So far no research concerning the omentin-1 (ITLN1) rs2274907 and vaspin (SERPINA12) rs2236242 polymorphisms has been carried out in a healthy pediatric population. We analyzed associations of these polymorphisms with anthropometric parameters, lipid profile, as well as adiponectin, leptin and soluble leptin receptor (sOB-R) levels in prepubertal healthy children, to search for their possible role in the risk of obesity and obesity-related disorders.Materials and Methods: Frequencies of these polymorphisms were analyzed by the restriction fragment length polymorphism in 89 normal-weight children. The body composition was measured by dual-energy X-ray absorptiometry. Serum levels of adipokines were measured using ELISA methods.Results: We observed differences in values of HDL-cholesterol (p = 0.002) and triglycerides (p = 0.039) in children carrying different genotypes of the ITLN1 rs2274907 polymorphism. In children carrying different genotypes of the SERPINA12 rs2236242 polymorphism differences in BMI (p =0.025) and BMI Z-score (p = 0.01) values were found. Significant relations between anthropometric parameters and levels of HDL-cholesterol and triglycerides were associated with minor alleles of the studied polymorphisms. In addition, leptin/sOB-R ratio was related to HDL-cholesterol (p = 0.004) and triglycerides (p = 0.03) levels in children carrying minor allele of the SERPINA12 rs2236242 SNP.Conclusions: We suggest that both ITLN1 rs2274907 and SERPINA12 rs2236242 polymorphisms influence body composition and lipid profile in prepubertal healthy children. Relations between anthropometric parameters, lipid and adipokine levels may be associated with minor alleles of the studied polymorphisms. The possible role of these polymorphisms in the modulation of the risk of obesity and obesity-related disorders in the later life might be considered.

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

AIMS/HYPOTHESIS

Higher concentrations of the adipokine omentin are associated with lower levels of cardiometabolic risk factors in experimental and cross-sectional studies, but with higher risk of type 2 diabetes and cardiovascular diseases in population-based cohort studies. However, it is unknown whether high omentin concentrations are associated with increased risk of cardiovascular events in people with established diabetes. Therefore, the present study investigated the association between serum omentin concentrations and the risk of cardiovascular events in individuals with diabetes.

METHODS

This prospective study was based on participants of the German ESTHER cohort with diabetes and without previous cardiovascular event. The ESTHER cohort consists of individuals aged 50-75 years at baseline who were recruited by their general practitioners. After exclusion of individuals with serum C-reactive protein ≥10 mg/l (≥95.24 nmol/l), the final analysis population consisted of 933 individuals. At baseline, serum omentin concentrations were measured by ELISA. Cox regression models were fitted to estimate HRs and their corresponding 95% CIs for associations of omentin tertiles with a composite endpoint of cardiovascular events and separately with incident myocardial infarction, stroke and cardiovascular death.

RESULTS

During 14 years of follow-up, 228 individuals experienced a primary cardiovascular event (myocardial infarction, stroke or cardiovascular death). After comprehensive adjustment for age, sex, BMI, metabolic and lifestyle factors and medication use, HRs (95% CIs) for the 2nd and 3rd tertile of omentin compared with the 1st tertile were: 1.24 (95% CI 0.86, 1.79) and 1.63 (1.15, 2.32) (p_trend = 0.005) for the composite cardiovascular endpoint; 1.39 (0.78, 2.47) and 1.71 (0.98, 2.99) (p_trend = 0.065) for incident myocardial infarction; 1.40 (0.78, 2.53) and 2.05 (1.17, 3.58) (p_trend = 0.010) for incident stroke; and 1.43 (0.85, 2.40) and 1.72 (1.04, 2.83) (p_trend = 0.040) for cardiovascular death. Effect estimates and p values were almost unaltered after additional adjustment for adiponectin.

CONCLUSIONS/INTERPRETATION

Higher omentin concentrations are associated with an increased risk for cardiovascular events in individuals with diabetes after adjustment for multiple cardiovascular risk factors. Given data from preclinical studies, it appears possible that this association reflects a compensatory, but insufficient upregulation of omentin concentrations as a response to stimuli that increase cardiovascular risk.

New Biomarkers as Prognostic Factors for Cardiovascular Complications in Type 2 Diabetic Patients

This study was initiated to explore some novel biomarkers like pro-inflammatory markers (chemerin and visfatin) and anti-inflammatory marker (omentin-1) as prognostic factors for cardiovascular complications in type 2 diabetic patients. Forty diabetic patients without cardiovascular disease, 40 diabetic patients with cardiovascular disease and twenty healthy control counterparts were included in this study. Serum chemerin, omentin-1 and visfatin levels were quantified. Receiver operating characteristic curve analysis was done to identify the cut off value for each marker. The mean serum level of chemerin was 57.65 ± 15.69 ng/l in diabetic patients versus 93.97 ± 26.62 ng/l for the cardio-diabetic ones (P < 0.0001). The mean serum level of omentin-1 was 8.77 ± 1.53 ng/ml in diabetic patients versus 1.76 ± 0.96 ng/ml for the cardio-diabetic ones (P < 0.0001). The mean level of visfatin was 1.44 ± 0.71 ug/l in diabetic patients versus 3.92 ± 3.32 ug/l for the cardio-diabetic ones (P < 0.0001). Chemerin and Visfatin levels were significantly enhanced in the cardio-diabetic patients with increasing C-reactive protein (CRP), triglycerides (TG), fasting blood glucose (FBG), micro-albumin and cholesterol. Omentin-1 level was significantly reduced in the cardio-diabetic patients with increasing CRP, TG, FBG, and cholesterol. It was observed that the area under curve for chemerin, omentin-1and visfatin was 0.877, 0.998 and 0.735, respectively. In conclusion, this study evidences that the measuring serum levels of chemerin, omentin-1 and visfatin may help in the prognosis of cardiovascular complications in type 2 diabetic patients.

Plasma omentin levels are inversely associated with atherosclerosis in type 2 diabetes patients with increased plasma adiponectin levels: a cross-sectional study

Background

Omentin and adiponectin are among the anti-inflammatory and anti-atherogenic adipokines that have potentially beneficial effects on cardiovascular disorders. Recent studies indicate a paradoxical relationship between adiponectin and cardiovascular mortality across many clinical settings including type 2 diabetes. In this study, we characterized the clinical features of type 2 diabetes patients with increased adiponectin levels and examined the association between omentin and atherosclerosis in those patients.

Methods

The subjects were 413 patients with type 2 diabetes. Fasting plasma omentin and total adiponectin levels were measured by enzyme-linked immunosorbent assay. The intima-media thickness (IMT) of the common carotid artery was measured by ultrasonography. The subjects were stratified according to the median value of plasma adiponectin.

Results

In high-adiponectin group, omentin levels were higher, while IMT tended to be greater than those in low-adiponectin group. The high-adiponectin group also exhibited older age, higher systolic blood pressure, lower kidney function, body mass index, and insulin resistance index compared to the low-adiponectin group. Multivariate analysis revealed that omentin levels were independently and negatively associated with IMT in high-adiponectin group, but not in low-adiponectin group, after adjusting for adiponectin levels and traditional cardiovascular risk factors. On the other hand, adiponectin levels were not significantly associated with IMT in either group.

Conclusions

Plasma omentin levels are inversely associated with IMT in type 2 diabetes patients with increased adiponectin levels and multiple cardiovascular risk factors. This study suggests a protective role of omentin against atherosclerosis in type 2 diabetes patients, which is potentially influenced by adiponectin level and cardiovascular risk status.

Clinical significance of circulating omentin levels in various malignant tumors: Evidence from a systematic review and meta-analysis

Aberrant circulating level of omentin has been reported in various solid tumors. However, whether decreased or increased levels of omentin contribute in cancer risk is remained controversial in different epidemiological studies. This comprehensive meta-analysis of observational studies was conducted to investigate the association between circulating omentin level and human cancer risk. An electronic search of health-related databases, was performed to identify all eligible studies in English, up to July 2019. Combined standard mean difference (SMD) with 95%CI was computed to assess the correlation of omentin levels with human cancer risk in a random effect model. The risk of publication bias was also evaluated using Funnel plot and Egger regression tests. A total of 16 studies with 1106 cases and 3078 healthy controls were included. Pooled SMD analysis based on the cancer type, revealed a strong correlation of omentin level and cancer risk in patients with colorectal (SMD = 2.08, 95%CI: 1.67-2.50, P < 0.001), prostate (SMD = 1.38, 95%CI: 1.15-1.62, P < 0.001), and breast (SMD = -0.78, 95%CI: -1.1, -0.45, P < 0.001) cancers. Elevated circulating omentin levels was also found in cancer patients with BMI ≥ 25 (SMD = 1.33, 95%CI: 0.52-2.15, P = 0.001) indicating a potential role for omentin in development of some obesity-linked cancers. The findings of this meta-analysis indicated a significant association of omentin level with greater risk of colorectal, pancreas, and breast tumors. Circulating omentin level may represent a potential novel biomarker for early detection of colorectal, prostate, and breast cancers especially in overweight/obese subjects. Further prospective well-designed studies are warranted to confirm our findings.

The association between omentin and diabetes: a systematic review and meta-analysis of observational studies

AIMS

A number of studies have examined the association between the serum levels of omentin and diabetes, but the findings have been inconclusive. Herein, we systematically reviewed available observational studies to elucidate the overall relationship between omentin and diabetes, including type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM), and impaired glucose tolerance (IGT) among adolescent and adult population.

METHODS

PubMed, Cochrane's Library, Science Direct, Scopus, Google Scholar, and ISI Web of Science databases were searched for all available literature until January 2019 for studies assessing the association between omentin and diabetes. The Newcastle-Ottawa Quality Assessment Scale was used to assess the quality of each study.

RESULTS

A total of 28 articles met the inclusion criteria and were included in our systematic review and meta-analysis. There was a significant association between serum omentin and diabetes (WMD-1.68; 95% CI, -2.17 to -1.19; P<0.001). The result of our sub-group analysis based on participants' health status revealed that omentin was significantly lower in T2DM and IGT subjects but not in T1DM ones compared to healthy controls.

CONCLUSION

We found that serum omentin level is significantly lower in T2DM and IGT patients but not in T1DM ones. These data could be used by clinicians for early diagnosis and management of diabetes. Furthermore, we need more clinical trials to investigate new agents which could influence omentin levels.

The potential of adipokines as biomarkers and therapeutic agents for vascular complications in type 2 diabetes mellitus

Over the past decades, there has been a major increase in type 2 diabetes (T2D) prevalence in most regions of the world. Diabetic patients are more prone to cardiovascular complications. Accumulating evidence suggests that adipose tissue is not simply an energy storage tissue but it also functions as a secretory tissue producing a variety of bioactive substances, also referred to as adipokines. The balance between pro-inflammatory adipokines and protective adipokines is disturbed in type 2 diabetes, this can be regarded as adipose tissue dysfunction which partly promote the pathogenesis of diabetes complications. In this review, we not only discuss the favorable adipokines like adiponectin, omentin, C1q tumor necrosis factor-related proteins, but also unfavorable ones like resisitin and visfatin, in the aim of finding potential biomarkers recommended for the clinical use in the diagnosis, prognosis and follow up of patients with T2D at high risk of developing cardiovascular diseases as well as leading to new therapeutic approaches.

Circulatory Omentin-1 levels but not genetic variants influence the pathophysiology of Type 2 diabetes

OBJECTIVE

Omentin-1, an anti-inflammatory protein, is secreted by the visceral adipose tissue. Altered levels of Omentin-1 are associated with obesity and Type 2 Diabetes (T2D). Although Omentin-1 is implicated in the insulin signaling pathway, the relationship between the genetic variants of Omentin-1 and T2D is not yet explored. The current study evaluates the association of Omentin-1 polymorphisms (rs2274907 A/T and rs1333062 G/T), its transcript and protein levels, and genotype-phenotype correlation with metabolic parameters and T2D susceptibility.

METHODS

Plasma and Peripheral Blood Mononuclear Cells (PBMCs) were separated from venous blood taken from 250 controls and 250 T2D patients recruited from Gujarat, India. Genomic DNA was isolated from PBMCs and genotyping of Omentin-1 variants was performed by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). RNA was isolated from Visceral Adipose Tissue (VAT) samples of 12 controls and 10 patients, and transcript levels of Omentin-1 were assessed by qPCR. Plasma Omentin-1 levels were estimated by ELISA. Fasting Blood Glucose, Body Mass Index (BMI) and plasma lipid profile were considered for the genotype-phenotype correlation analysis.

RESULTS

Our study revealed no association of Omentin-1 genetic variants with T2D risk (p > 0.05). However, the AT genotype of Omentin-1 rs2274907 A/T polymorphism was associated with increased BMI (p = 0.0247). Plasma Omentin-1 levels were significantly decreased (p < 0.0001) however, increased VAT Omentin-1 transcript levels (p = 0.0127) were observed in T2D patients.

CONCLUSION

Our findings suggest that decreased circulatory Omentin-1 levels could pose a risk towards T2D susceptibility.

Plasma omentin levels are associated with vascular endothelial function in patients with type 2 diabetes at elevated cardiovascular risk

AIMS

Omentin is an adipokine that has protective effects against cardiovascular damage. Previous studies showed an inverse relationship between omentin and obesity, diabetes, and cardiovascular disease. This study aimed to investigate the association between omentin and vascular endothelial function in patients with type 2 diabetes (T2D).

METHODS

The subjects were 425 patients with T2D and 223 non-diabetic controls. Fasting plasma omentin levels were measured by enzyme-linked immunosorbent assay, and the endothelium-dependent, flow-mediated dilatation (FMD) was measured by ultrasonography.

RESULTS

Plasma omentin levels were higher, while FMD was lower in participants with T2D than in non-diabetic controls. No significant correlation was found between plasma omentin levels and FMD in either non-diabetic controls or participants with T2D on multivariate analysis. However, stratified analysis in T2D patients revealed that plasma omentin levels were independently and positively associated with FMD in high cardiovascular risk subgroups according to age (≥65 years), estimated glomerular filtration rate (<60 mL/min/1.73 m²), or preexisting cardiovascular diseases but not in low-risk subgroups.

CONCLUSIONS

Plasma omentin levels are independently associated with endothelial function in subgroups of patients with T2D at elevated cardiovascular risk. This study suggests a protective role of omentin against endothelial dysfunction, particularly in high-risk patients.

Exercise and Omentin: Their Role in the Crosstalk Between Muscle and Adipose Tissues in Type 2 Diabetes Mellitus Rat Models

This study aims to analyze the effects of resisted, aerobic, and combined exercises on omentin levels in visceral adipose tissue and muscle of rats with experimental diabetes to verify whether these adipokines are related to the glucose pathway and inflammation process in this model. Male Wistar rats received a high-fat diet for 4 weeks and a low dose of streptozotocin (35 mg/kg) to induce experimental diabetes. After inducing diabetes, the animals were divided into 4 experimental groups (n = 10): diabetic control (C); resistance training (RT); aerobic training (AT); and combined training (CT). The groups were exercised for 12 weeks, 3 times/week, where: RT means the stair climbing protocol until exhaustion; AT is the 30 min/day reaching 20 m/min protocol, and CT is the combination of RT and AT. The AT group showed reduced retroperitoneal and mesenteric adipose tissue and abdominal fat deposits. Our study also showed a possible control of blood glucose, as well as decreased Interleukin 6 (IL-6) and C-reactive protein, increased circulating adiponectin and increased omentin in visceral adipose tissue. In addition, the AT group affected the glucose pathway by stimulating phosphorylation of Akt in muscle tissue. Omentin also showed a strong positive correlation with adiponectin and a moderate negative correlation with IL-6. Thus, our findings indicated that omentin in type 2 diabetes is changed by AT. Furthermore, increased omentin levels had a close association with the glucose pathway by stimulating phosphorylation of Akt in muscle tissue and with IL-6 in serum, suggesting that omentin is likely to have anti-inflammatory and protective action in experimental diabetes.

Serum omentin-1 levels in type 2 diabetic obese women in relation to glycemic control, insulin resistance and metabolic parameters

Background

Omentin-1 a new anti-inflammatory adipokine has been identified as a major visceral (omental) secretory adipokine which plays important roles in glucose homeostasis, lipid metabolism, insulin resistance and diabetes. The aim of our study was to evaluate serum omentin-1 levels in type 2 diabetic obese females and assess its relation with glycemic control, insulin resistance and metabolic parameters.

Methods

The study included 60 obese type 2 diabetic females and 30 healthy female subjects formed the control group. They subjected to full clinical examination, weight, height, waist and hip circumference. Fasting (blood glucose, insulin, lipid profile, omentin-1) and HbA1c were measured. BMI and HOMA-IR were calculated. Our data analyzed and expressed in terms of mean ± SD. Pearson correlation performed to study the correlation of serum omentin-1 in relation to glycemic control, insulin resistance and metabolic parameters in the studied groups.

Results

We found significant decrease in serum omentin-1 levels in cases with mean ± SD (16.5 ± 2.6 pg/ml) compared to controls (25.3 ± 1.0 pg/ml) (P < 0.001). We also found strong significant negative correlations between serum omentin-1 and (BMI, fasting insulin, HOMA-IR) (r = −0.909, −0.853, −0.511) respectively (P < 0.001) and systolic blood pressure (r = −0.274, p = 0.031). The best cut off point of serum omentin-1 was 22.2 pg/ml to differentiate cases from controls using ROC curve analysis.

Conclusion

Our study has shown significant low levels of serum omentin-1 in obese type 2 diabetic females in comparison to healthy subjects. Omentin-1 inversely related to obesity, insulin resistance and SBP. No significant associations with glycemic control and fasting lipids. Serum omentin-1 can be used as a biomarker for obesity related metabolic disorders.

Role of omentin 1 and IL-6 in type 2 diabetes mellitus patients with diabetic nephropathy

AIMS

Diabetic nephropathy (DN) is one of the major chronic vascular complication of T2DM and leading cause of end-stage renal disease. Inflammation is one of the proposed pathway which explains microvascular complications in T2DM but exact mechanism is still unclear. Omentin-1 is an anti-inflammatory adipokine which promotes insulin signaling. IL-6 is a multifunctional cytokine having role in immune and inflammatory responses. The present study was conducted to elucidate the role of omentin-1 and IL-6 in the pathogenesis of DN and its association with insulin resistance. We aimed to assess and compare the serum levels of omentin-1 and IL-6 in T2DM patients with and without DN.

MATERIALS & METHODS

Our study comprised of 2 groups of 41 each. Group A (controls) included T2DM without nephropathy patients and group B (cases) included T2DM nephropathy patients. Parameters studied were serum omentin-1, insulin, IL-6, fasting blood glucose, urea, creatinine, lipid profile, HOMA-IR, eGFR and BMI.

RESULTS & CONCLUSION

Omentin-1 (p=0.03) was significantly decreased; concomitantly, significant increase in levels of insulin (p=0.004), IL-6 (p=0.023) and HOMA-IR (p=0.0004) were found in cases compared to controls. Bivariate analysis showed eGFR correlating positively with omentin-1 and negatively with insulin in the study population. Our study results, based on serum omentin-1 and IL-6 data suggest important role played by inflammatory mechanism and insulin resistance in the pathogenesis of diabetic nephropathy in type 2 diabetes mellitus patients.

Independent and opposite associations of serum levels of omentin-1 and adiponectin with increases of glycaemia and incident type 2 diabetes in an older population: KORA F4/FF4 study

OBJECTIVE

Cross-sectional studies found that higher levels of the novel adipokine omentin-1 were associated with higher adiponectin and lower levels of risk factors for type 2 diabetes, but its relevance for incident type 2 diabetes is currently not understood. Therefore this study investigated whether serum omentin-1 was associated with changes in glycaemia and incident type 2 diabetes independently of adiponectin.

DESIGN AND METHODS

The study was based on participants aged 62-81 years from the population-based Cooperative Health Research in the Region of Augsburg (KORA) F4/FF4 cohort. Associations of baseline serum levels of omentin-1 and adiponectin with changes in glycaemia were assessed in 471 non-diabetic participants, and associations between both adipokines and incident type 2 diabetes were assessed in 76 cases and 430 non-cases (follow-up time 6.5 years). Multivariable linear and logistic regression models were adjusted for multiple potential confounders.

RESULTS

Higher serum levels of omentin-1 were associated with increases in fasting glucose, 2-h glucose and HbA1c (all P < 0.001) and with incident type 2 diabetes (adjusted odds ratio (OR) (95% CI): 1.40 (1.03; 1.90) per s.d. of log₂-transformed omentin-1; P = 0.032). These associations were independent from adiponectin levels, which showed associations with changes in glycaemia and risk of type 2 diabetes in the opposite direction. We found no statistically significant interactions of omentin-1 with adiponectin or sex in the association with incident type 2 diabetes (all P > 0.1).

CONCLUSIONS

Systemic levels of omentin-1 were positively associated with increases in glycaemia and incident type 2 diabetes in this older population. These associations were independent of potential confounders including adiponectin.

Insights into the Link Between Obesity and Cancer

PURPOSE OF REVIEW

Adipocytes have adapted to store energy in the form of lipid and also secrete circulating factors called adipokines that signal to other tissues to coordinate energy homeostasis. These functions are disrupted in the setting of obesity, promoting the development of diseases such as diabetes, cardiovascular disease, and cancer.

RECENT FINDINGS

Obesity is linked to an increased risk of many types of cancer and increased cancer-related mortality. The basis for the striking association between obesity and cancer is not well understood. Here, we review the cellular and molecular pathways that appear to be involved in obesity-driven cancer. We also describe possible therapeutic considerations and highlight important unanswered questions in the field.

Association of Serum Omentin-1 Concentrations with the Presence of Atrial Fibrillation

BACKGROUND Omentin-1 is one of the adipokines associated with obesity, diabetes, and coronary heart disease development. We determined to investigate whether serum omentin-1 concentrations were correlated with the presence of atrial fibrillation (AF). MATERIAL AND METHODS Serum omentin-1 concentrations were examined in a cross-sectional population that included 220 patients with AF (70 with paroxysmal AF, 78 with persistent AF, and 72 with permanent AF) and 115 healthy controls. RESULTS Reduced serum omentin-1 concentrations were found in AF patients compared to the controls. In addition, patients with permanent AF had lower serum omentin-1 concentrations compared to patients with persistent AF and patients with paroxysmal AF. Significantly decreased serum omentin-1 concentrations were observed in persistent AF patients compared to paroxysmal AF patients. Spearman correlation analysis suggested that serum omentin-1 concentrations were negatively correlated with left atrial diameter in AF patients. CONCLUSIONS Serum omentin-1 concentrations were correlated with the presence of AF and atrial remolding.

Lactoferrin, a Pleiotropic Protein in Health and Disease

SIGNIFICANCE

Lactoferrin (Lf) is a nonheme iron-binding glycoprotein strongly expressed in human and bovine milk and it plays many functions during infancy such as iron homeostasis and defense against microorganisms. In humans, Lf is mainly expressed in mucosal epithelial and immune cells. Growing evidence suggests multiple physiological roles for Lf after weaning.

RECENT ADVANCES

The aim of this review is to highlight the recent advances concerning multifunctional Lf activities.

CRITICAL ISSUES

First, we will provide an overview of the mechanisms related to Lf intrinsic synthesis or intestinal absorption as well as its interaction with a wide spectrum of mammalian receptors and distribution in organs and cell types. Second, we will discuss the large variety of its physiological functions such as iron homeostasis, transportation, immune regulation, oxidative stress, inflammation, and apoptosis while specifying the mechanisms of action. Third, we will focus on its recent physiopathology implication in metabolic disorders, including obesity, type 2 diabetes, and cardiovascular diseases. Additional efforts are necessary before suggesting the potential use of Lf as a diagnostic marker or as a therapeutic tool.

FUTURE DIRECTIONS

The main sources of Lf in human cardiometabolic disorders should be clarified to identify new perspectives for future research and develop new strategies using Lf in therapeutics. Antioxid. Redox Signal. 24, 813-836.

A role for novel adipose tissue-secreted factors in obesity-related carcinogenesis

Obesity, a pandemic disease, is caused by an excessive accumulation of fat that can have detrimental effects on health. Adipose tissue plays a very important endocrine role, secreting different molecules that affect body physiology. In obesity, this function is altered, leading to a dysfunctional production of several factors, known as adipocytokines. This process has been linked to various comorbidities associated with obesity, such as carcinogenesis. In fact, several classical adipocytokines with increased levels in obesity have been demonstrated to exert a pro-carcinogenic role, including leptin, TNF-α, IL-6 and resistin, whereas others like adiponectin, with decreased levels in obesity, might have an anti-carcinogenic function. In this expanding field, new proteomic techniques and approaches have allowed the identification of novel adipocytokines, a number of which exhibit an altered production in obesity and type 2 diabetes and thus are related to adiposity. Many of these novel adipocytokines have also been identified in various tumour types, such as that of the breast, liver or endometrium, thereby increasing the list of potential contributors to carcinogenesis. This review is focused on the regulation of these novel adipocytokines by obesity, including apelin, endotrophin, FABP4, lipocalin 2, omentin-1, visfatin, chemerin, ANGPTL2 or osteopontin, emphasizing its involvement in tumorigenesis.

Coronary patients with high plasma omentin are at a higher cardiovascular risk

The adipokine omentin, also known as intelectin, is a secretory protein, expressed in visceral adipose tissue and is highly abundant in plasma. It is involved in the development of chronic inflammatory diseases, but nothing is known about its impact on the cardiovascular event risk. Here, plasma omentin was measured in 295 patients undergoing coronary angiography for the evaluation of established or suspected stable coronary artery disease (CAD). Patients were separated according to the median plasma omentin concentrations into a high and low omentin group and cardiovascular events occurring during a period of 3.5 years have been recorded. We observed that patients within the high omentin group had significantly more cardiovascular events than patients in the low omentin group. This was true even if using different study endpoints. This article describes data related to a research article titled “High Plasma Omentin Predicts Cardiovascular Events Independently From the Presence and Extent of Angiographically Determined Atherosclerosis” (Saely et al., 2015) [1].

Omentin-1 plasma levels and cholesterol metabolism in obese patients with diabetes mellitus type 1: impact of weight reduction

Background:

Omentin-1 is an anti-inflammatory adipokine produced preferentially by visceral adipose tissue. Plasma levels of omentin-1 are decreased in obesity and other insulin-resistant states. Insulin resistance contributes to the changes of cholesterol synthesis and absorption as well. The aim of this study was to characterise omentin-1 plasma levels in obese patients with diabetes mellitus type 1 during weight reduction, and to elucidate the relationship between cholesterol metabolism and omentin-1.

Methods:

Plasma levels of omentin-1 were measured in obese type 1 diabetics (n=14, body mass index >30 kg m⁻², age 29–62 years) by enzyme-linked immunosorbent assay (BioVendor). Gas chromatography with flame ionisation detector (Fisons Plc.,) was used to measure squalene and non-cholesterol sterols—markers of cholesterol synthesis and absorption (phase I). Measurements were repeated after 1 month (phase II; 1 week of fasting in the hospital setting and 3 weeks on a diet containing 150 g saccharides per day) and after 1 year (phase III) on a diet with 225 g saccharides per day.

Results:

Omentin-1 plasma levels were stable during phases I and II, but significantly increased (P<0.001) during phase III. Omentin-1 plasma dynamics were significantly associated with plasma levels of high-density lipoprotein (P=0.005) and triacylglycerols (P=0.01), as well as with lathosterol (P=0.03).

Conclusion:

Omentin-1 plasma levels significantly increased during the weight reduction programme. Omentin-1 plasma dynamics suggest a close relationship with cholesterol metabolism.

Serum omentin-1 levels as a possible risk factor of mortality in patients with diabetes on haemodialysis

AIM

The main cause of mortality in haemodialysis (HD) patients is cardiovascular disease. Serum omentin-1 level was found to be associated with cardio-metabolic disorders. The aim of this study was to examine the role of omentin-1 as a predictor of mortality in a group of diabetes positive HD patients.

METHODS

A total of 120 prevalent HD patients were included in the study from December 2012 to May 2014. Patients were divided into two groups according to the presence or absence of diabetes. Venous blood samples were taken at months 0 and 18 following an overnight fast (prior to a midweek HD session). Serum omentin-1 level was assessed by enzyme-linked immunosorbent assay.

RESULTS

A total of 84 HD patients were analysed at the end of an 18-month follow-up. Omentin-1 levels of HD patients with diabetes were found to be lower than of HD patients without diabetes (9.1±5.8 ng/mL vs. 11.4±4.1 ng/mL, respectively; P=0.015) at the end of follow-up. Omentin-1 levels of survived patients with diabetes were found to be higher than of nonsurvived patients with diabetes (16.5±10.1 ng/mL vs. 12.9±5.3 ng/mL, respectively; P=0.045). During follow-up, 36 patients (30%) died, of whom 25 had diabetes (34%).

CONCLUSIONS

Serum omentin-1 levels were significantly lower in HD patients with diabetes. A decrease in omentin-1 levels could be an independent mortality risk factor in this patient group. Further investigation in a greater number of patients is needed.