Omentin as a novel biomarker of metabolic risk factors

Association of serum omentin levels with microvascular complications of type 2 diabetes mellitus: a systematic review and meta-analysis

Background and aims

Type 2 diabetes mellitus (T2DM) is a chronic condition associated with various microvascular complications, including neuropathy, retinopathy, and nephropathy. Recent studies have suggested a potential association between serum omentin levels and the risk of developing microvascular complications in patients with T2DM. However, the existing evidence remains inconclusive. Therefore, we conducted a systematic review and meta-analysis to examine the association between serum omentin levels and microvascular complications in T2DM patients.

Methods

A comprehensive search was conducted in PubMed, Scopus, and Google Scholar databases to retrieve relevant articles published up to May 2023. Observational studies investigating omentin levels association with microvascular complications in T2DM patients were included. Data was extracted and hence analyzed.

Results

A total of seven cross-sectional articles met the inclusion criteria, with a total population of 1587 participants. The meta-analysis revealed a significant association between serum omentin levels and microvascular complications in patients with T2DM. Serum omentin levels were lower in patients with microvascular complications than in those without complications (Mean difference, 95% confidence interval: -1.31 [-2.50, -0.13], I2 = 99.62%).

Conclusion

This systematic review and meta-analysis provides evidence supporting an association between serum omentin levels and microvascular complications in patients with T2DM. The findings suggest that Omentin may be lower in T2DM patients with microvascular complications. Further research is warranted to elucidate the underlying mechanisms and explore the clinical implications of these findings.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01359-2.

Enhancing cardiometabolic health: unveiling the synergistic effects of high-intensity interval training with spirulina supplementation on selected adipokines, insulin resistance, and anthropometric indices in obese males

This study investigated the combined effects of 12 weeks of high-intensity interval training (HIIT) and spirulina supplementation on adipokine levels, insulin resistance, anthropometric indices, and cardiorespiratory fitness in 44 obese males (aged 25-40 years). The participants were randomly assigned to one of four groups: control (CG), supplement (SG), training (TG), or training plus supplement (TSG). The intervention involved daily administration of either spirulina or a placebo and HIIT three times a week for the training groups. Anthropometric indices, HOMA-IR, VO2peak, and circulating adipokines (asprosin and lipocalin2, omentin-1, irisin, and spexin) were measured before and after the 12-week intervention. Post-intervention analysis indicated differences between the CG and the three interventional groups for body weight, fat-free mass (FFM), percent body fat (%BF), HOMA-IR, and adipokine levels (p < 0.05). TG and SG participants had increased VO2peak (p < 0.05). Spirulina supplementation with HIIT increased VO2peak, omentin-1, irisin, and spexin, while causing decreases in lipocalin-2 and asprosin levels and improvements in body composition (weight, %fat), BMI, and HOMA-IR. Notably, the combination of spirulina and HIIT produced more significant changes in circulating adipokines and cardiometabolic health in obese males compared to either supplementation or HIIT alone (p < 0.05). These findings highlight the synergistic benefits of combining spirulina supplementation with HIIT, showcasing their potential in improving various health parameters and addressing obesity-related concerns in a comprehensive manner.

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.

Exploring the Diversity of Visceral, Subcutaneous and Perivascular Adipose Tissue in a Vascular Surgery Population

The prevalence of obesity has doubled, with a concomitant increase in cardiovascular disease. This study aimed to compare the characteristics of visceral, subcutaneous and peri-aortic adipose tissue determined with computed tomography (CT) scans and to correlate them with cardiovascular risk factors, anthropometric measures and medication. An observational and prospective study was conducted, and 177 subjects were included. Peri-aortic adipose tissue had the highest density, while the subcutaneous adipose tissue had the lowest. The density of subcutaneous adipose tissue differs from the density of visceral (p = 0.00) and peri-aortic adipose tissue (p = 0.00). Smokers/ex-smokers had a lower area (p = 0.00) and density (p = 0.02) of subcutaneous adipose tissue. Multiple linear regression analysis showed that sex was a predictor of subcutaneous adipose tissue area (β = -0.27, t = -3.12, p = 0.00) but smoking habits were not. After controlling for sex, we found that the association between smokers/ex-smokers and area of subcutaneous adipose tissue was lost, but the association with density persisted. Patients with hypertension had a higher visceral adipose tissue area, and this relationship was maintained even after adjusting for gender. Peri-aortic adipose tissue is similar to visceral and distinct from subcutaneous adipose tissue. Cardiovascular risk factors have different influences in distinct adipose compartments.

Bombax ceiba Linn. leaf extract rich in phenolic compounds to mitigate non-alcoholic fatty liver-related complications in experimental model

OBJECTIVES

Obesity, diabetes mellitus, insulin resistance (IR), and hypertriglyceridemia are common features observed in non-alcoholic fatty liver diseases (NAFLD). There is a critical medical necessity to find novel therapeutics that can halt the development of NAFLD.

METHODS

Bombax ceiba Linn. leaf extract was prepared and its phytochemical profile was determined. Standard and high carbohydrate high-fat diets (HCHF) were prepared. Rats were fed HCHF for 18 weeks to induce a non-alcoholic fatty liver (NAFL) model. Forty male rats were divided into control, B. ceiba Linn. leaf extract, NAFL, prophylactic, and treated groups. Serum fasting blood sugar (FBS), insulin, insulin resistance (HOMA-IR), cholesterol, high-density lipoprotein (HDL), triglycerides (TG), low density lipoprotein (LDL), alanine aminotransferase (ALT), aspartate aminotransferase (AST), intelectin-1 (ITLN1), p38 MAP kinase (MAPK), peroxisome proliferator-activated receptor alpha (PPAR-α), and interleukin-6 (IL-6) were evaluated.

RESULTS

Data obtained showed that HCHF-induced NAFL resulting in a significant increase in FBS, serum insulin, HOMA-IR, cholesterol, LDL, TG, ALT, AST, and IL-6 and a significant decrease in serum levels of HDL, ITLN1, p38 MAP kinase, and PPAR-α compared to the control group. The analysis of B. ceiba Linn. leaf extract showed high content of phenol compounds which may cause a significant decrease in the levels of FBS, insulin, HOMA-IR values, lipid profile, and levels of IL-6 while a significant increase in serum levels of LDL, ITLN1, p38 MAP kinase, and PPAR-α compared to the NAFL group.

CONCLUSIONS

B. ceiba Linn. Leaf extract is a highly protective and promising therapeutic agent against inflammation and oxidative stress in the NAFLD model induced by HCHF.

Mediterranean Diet Improves Plasma Biomarkers Related to Oxidative Stress and Inflammatory Process in Patients with Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) shows liver fat depots without alcohol consumption. NAFLD does not have specific drug therapies, with a healthy lifestyle and weight loss being the main approaches to prevent and treat NAFLD. The aim was to assess the antioxidant and pro-inflammatory state in patients with NAFLD after 12-month-lifestyle intervention depending on the change in adherence to a Mediterranean diet (AMD). Antioxidant and inflammatory biomarkers were measured in 67 adults (aged 40–60 years old) diagnosed with NAFLD. Anthropometric parameters and dietary intake were measured by a validated semi-quantitative 143-item food frequency questionnaire. The nutritional intervention improved anthropometric and biochemical parameters after a 12-month follow-up. However, decreases in alanine aminotransferase (ALT) and C reactive protein (CRP) were higher in participants with high AMD, which also showed higher improvement in physical fitness (Chester step test) and intrahepatic fat contents. The intervention reduced plasma levels of malondialdehyde, myeloperoxidase, zonulin, and omentin, and increased resolvin D1 (RvD1), whereas the decrease in leptin, ectodysplasin-A (EDA), cytokeratin-18 (CK-18), interleukin-1ra (IL-1ra) and endotoxin was only significant in participants with higher AMD. The current study showed that a one-year nutritional intervention improved main NAFLD features such as body mass index, IFC, liver enzymes, and prooxidant and proinflammatory status. There was also a decrease in the concentration of plasmatic endotoxin, suggesting an improvement in intestinal permeability. These health benefits were more evident in participants that improved AMD to a greater extent. The trial was registered at ClinicalTrials.gov with registry number NCT04442620.

Omentin Modulates Chronic Cardiac Remodeling After Myocardial Infarction

Background: Omentin, a circulating adipokine, is downregulated in complications of obesity, including heart disease. Here, we investigated whether omentin modulates adverse cardiac remodeling in mice after myocardial infarction (MI). Methods and Results: Transgenic mice expressing the human omentin gene in fat tissue (OMT-Tg) and wild-type (WT) mice were subjected to permanent ligation of the left anterior descending coronary artery (LAD) to induce MI. OMT-Tg mice had a higher survival rate after permanent LAD ligation than WT mice. Moreover, OMT-Tg mice had lower heart weight/body weight (HW/BW) and lung weight/body weight (LW/BW) ratios at 4 weeks after coronary artery ligation compared with WT mice. OMT-Tg mice also showed decreased left ventricular diastolic diameter (LVDd) and increased fractional shortening (%FS) following MI. Moreover, an increase in capillary density in the infarct border zone and a decrease in myocardial apoptosis, myocyte hypertrophy, and interstitial fibrosis in the remote zone following MI, were more prevalent in OMT-Tg than WT mice. Finally, intravenous administration of adenoviral vectors expressing human omentin to WT mice after MI resulted in decreases in HW/BW, LW/BW, and LVDd, and an increase in %FS. Conclusions: Our findings document that human omentin prevents pathological cardiac remodeling after chronic ischemia, suggesting that omentin represents a potential therapeutic molecule for the treatment of ischemic heart disease.

Nutritional Status and Selected Adipokines in Children with Irritable Bowel Syndrome

BACKGROUND

The aim of this study was to assess the nutritional status and serum concentrations of adipokines in children with irritable bowel syndrome (IBS) and healthy controls. We also sought to evaluate their relation to metabolic parameters.

METHODS

We studied 33 IBS patients (11 girls, 22 boys) aged 5-17 years and 30 healthy age-matched controls (11 girls, 19 boys). The analysis included anthropometric measurements, body composition parameter measurements using bioimpedance, and biochemical tests and measurements of serum concentrations of leptin, adiponectin, chemerin, and omentin-1.

RESULTS

The results of the anthropometric measurements were comparable between the patients and the controls. The patients had higher triglycerides, HOMA-IRs, and chemerin concentrations than the healthy subjects. The HDL cholesterol and omentin-1 levels were lower than in the controls. Leptin and adiponectin did not differ significantly between the groups. An analysis of the receiver operator curves (ROCs) showed that serum concentrations of chemerin ≥ 232.8 ng/mL had 30% sensitivity and 87% specificity when they were used to differentiate between children with IBS and healthy subjects. In the case of serum omentin-1 concentrations ≤ 279.4 ng/mL, the sensitivity and specificity were 60% and 80%, respectively.

CONCLUSIONS

The nutritional status of children with IBS did not differ from that of the healthy controls. We found significant differences in serum chemerin and omentin-1 concentrations between IBS patients and healthy children. These adipokines could be used as IBS biomarkers as they demonstrate good specificity and moderate sensitivity. The serum concentrations of chemerin and omentin-1 in IBS patients were related to nutritional status and insulin resistance.

Characterization of an intelectin-1 (Itln1) knockout mouse model

Intelectins are carbohydrate-binding proteins implicated in innate immunity and highly conserved across chordate evolution, including both ascidians and humans. Human intelectin-1 (ITLN1) is highly abundant within the intestinal mucosa and binds microbial but not host glycans. Genome-wide association studies identified SNPs in ITLN1 that are linked to susceptibility for Crohn's disease. Moreover, ITLN1 has been implicated in the pathophysiology of obesity and associated metabolic disease. To gain insight on biological activities of human ITLN1 in vivo, we developed a C57BL/6 mouse model genetically targeting the gene encoding the functional mouse ortholog. In wild-type C57BL/6 mice, both mRNA and protein analysis showed high expression of Itln1 in the small intestine, but manifold lower levels in colon and other extraintestinal tissues. Whereas intestinal expression of human ITLN1 localizes to goblet cells, our data confirm that mouse Itln1 is expressed in Paneth cells. Compared to wild-type littermate controls, mice homozygous for the Itln1 hypomorphic trapping allele had reduced expression levels of Itln1 expression (~10,000-fold). The knockout mice exhibited increased susceptibility in an acute model of experimentally induced colitis with 2% w/v dextran sulfate sodium (DSS). In a model of chronic colitis using a lower dose of DSS (1.5% w/v), which enabled a detailed view of disease activity across a protracted period, no differences were observed in body weight, fecal texture, hemoccult scores, food/water intake, or colon length at necropsy, but there was a statistically significant genotype over time effect for the combined fecal scores of disease activity. In model of diet-induced obesity, using two western-style diets, which varied in amounts of sugar (as sucrose) and saturated fat (as lard), mice with Itln1 expression ablated showed no increased susceptibility, in terms of weight gain, food intake, plasma markers of obesity compared to wildtype littermates. While the mouse genetic knockout model for Itln1 holds promise for elucidating physiological function(s) for mammalian intelectins, results reported here suggest that Itln1, a Paneth cell product in C57BL/6 mice, likely plays a minor role in the pathophysiology of chemically induced colitis or diet-induced obesity.

Blood and Urinary Biomarkers of Antipsychotic-Induced Metabolic Syndrome

Metabolic syndrome (MetS) is a clustering of at least three of the following five medical conditions: abdominal obesity, high blood pressure, high blood sugar, high serum triglycerides, and low serum high-density lipoprotein (HDL). Antipsychotic (AP)-induced MetS (AIMetS) is the most common adverse drug reaction (ADR) of psychiatric pharmacotherapy. Herein, we review the results of studies of blood (serum and plasma) and urinary biomarkers as predictors of AIMetS in patients with schizophrenia (Sch). We reviewed 1440 studies examining 38 blood and 19 urinary metabolic biomarkers, including urinary indicators involved in the development of AIMetS. Among the results, only positive associations were revealed. However, at present, it should be recognized that there is no consensus on the role of any particular urinary biomarker of AIMetS. Evaluation of urinary biomarkers of the development of MetS and AIMetS, as one of the most common concomitant pathological conditions in the treatment of patients with psychiatric disorders, may provide a key to the development of strategies for personalized prevention and treatment of the condition, which is considered a complication of AP therapy for Sch in clinical practice.

The Emerging Role of Intelectin-1 in Cancer

BACKGROUND

Intelectin (ITLN) is an adipokine with two homologs-ITLN1 and ITLN2-that has various physiological functions. Studies analyzing the relationship between ITLN and cancer are focused on ITLN1; the available literature on ITLN2 and cancer is limited. This review aims to evaluate the role of ITLN1 in cancer without imposing any inclusion criteria, to examine pro- and anticancer roles for ITLN1 and to discuss whether the relationship between ITLN and cancer is mediated by obesity.

FINDINGS

Overall, ITLN1 level was highly variable in cancer patients but different from healthy individuals. Compared with control groups, patients with gastrointestinal and prostate cancer showed increased concentrations of circulating ITLN1, while patients with gynecological, breast, bladder, and renal cancer had lower ITLN1 levels. Several studies also evaluated tissue and tumor expression of ITLN1. In gastrointestinal cancer, ITLN1 was increased in tumor tissue compared with adjacent healthy tissue and elevated in the visceral adipose tissue of patients compared with controls. Consequently, the high levels of circulating ITLN1 might be determined by the tumor and by the cancer-associated weight loss in gastrointestinal cancer. ITLN1 can activate the phosphoinositide-3-kinase-protein kinase B/Akt (PI3K/Akt) pathway. The improper regulation of this pathway may contribute to a series of cellular events that favor tumor development and progression. Obesity has been linked with an increased risk of developing some cancers. Indeed, low circulating ITLN1 levels may be a marker of the metabolic effects of obesity, rather than obesity per se, and might contribute to a deregulation of the PI3K/Akt pathway.

CONCLUSIONS

ITLN1 could be associated with cancer formation and progression. Since circulating ITLN1 levels are highly variable and differ between cancer types, the local tumor production of ITLN1 could be more relevant in determining malignant behavior. Future research should aim to identify the source of ITLN1 variability, to understand the differences in ITLN1 between distinct tumor types, and to further explore the signaling pathways through which this adipokine influences cancer biology.

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.

Omentin as an Independent Predictor of Metabolic Syndrome and Obesity Among Adolescents in Northeast China

PURPOSE

We investigated the association of omentin with metabolic syndrome (MetS), MetS components, and obesity in adolescents.

METHODS

A total of 742 middle-school students from Liaoyang City were enrolled in this cross-sectional study using the stratified cluster sampling method. Clinical information and blood samples were collected, and serum omentin levels were measured using enzyme-linked immunosorbent assay.

RESULTS

Mean plasma omentin levels were lower in male than in female participants (88.25 (interquartile range 63.02-133.61) vs 99.46 (interquartile range 69.08-188.35) ng/L, P = 0.004). The participants were divided into four groups according to the quartile (Q) values of omentin from low to high. With increasing omentin levels from Q1 to Q4, the age of adolescents and the proportion of males gradually increased (P < 0.05), whereas the body mass index (BMI) (P < 0.05) and prevalence of MetS (P > 0.05) tended to decrease. Omentin levels were significantly and negatively correlated with waist circumference and BMI (correlation coefficients of -0.099 and -0.115, respectively). Regression analysis showed that omentin level was independently associated with the risk of MetS (Odds ratio, OR = 0.639, 95% confidence interval, CI (0.432, 0.945)), which was attributed to the association with central obesity (OR = 0.775, 95% CI (0.605, 0.993)) among MetS components. Increased omentin levels also indicated a reduced risk of obesity (OR = 0.700, 95% CI (0.563, 0.870)).

CONCLUSION

Omentin is an independent predictor of MetS and obesity among adolescents in northeast China.

The relation of omentin gene expression and glucose homeostasis of visceral and subcutaneous adipose tissues in non-diabetic adults

BACKGROUND

Adipose tissue (AT) is a passive reservoir for energy storage and an active endocrine organ responsible for synthesizing bioactive molecules called adipokines. Omentin is known as an anti-inflammatory adipokine that can modulate insulin sensitivity. The present study aimed to investigate the relationship between omentin mRNA expression and glucose homeostasis of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) in non-diabetic adults.

METHODS

VAT and SAT adipose tissues were collected from 137 adults aged ≥ 18 years hospitalized for abdominal surgery. Before surgery, preoperative blood samples were taken from the participants to measure fasting plasma glucose, insulin, and triglyceride. BMI, HOMA-IR, HOMA-B, and QUICKI were calculated. Insulin levels were measured with Mercodia kits using enzyme-linked immunosorbent assay (ELISA). In order to obtain omentin mRNA expression, real-time PCR was performed.

RESULTS

Overall, 91 (66.4%) subjects were healthy [without insulin resistance (IR)], and 46 (33.6%) participants were with IR. In healthy and IR subjects, omentin gene expression was 1.04 and 2.32, respectively in VAT, and 3.06 and 1.30, respectively, in SAT (P > 0.05). After controlling for age and BMI, linear regression analysis indicated a significant positive association of SAT omentin expression with insulin concentration (β = 0.048; 95% CI 0.009, 0.088, P = 0.017) and HOMA-IR (β = 0.173; 95% CI 0.023, 0.323, P = 0.014). Moreover, a negative association of SAT omentin expression with HOMA-B (β = - 0.001; 95% CI 0.002, - 0.001, P < 0.001) was observed.

CONCLUSION

This study's finding confirms a direct association between IR with omentin mRNA levels in SAT. Besides, the indicator of insulin sensitivity had an inverse association with omentin gene expression in SAT. This aspect of research suggests that omentin secretion from SAT has a strong link with insulin regulation.

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.

Metabolic syndrome and hidradenitis suppurativa: epidemiological, molecular, and therapeutic aspects

Hidradenitis suppurativa (HS) is a chronic, suppurative condition of the pilosebaceous unit. Patients suffering from HS demonstrate a molecular profile in keeping with a state of systemic inflammation and are often found to fit the criteria for a diagnosis of metabolic syndrome (MetS). In this paper, we review the literature with regards to established data on the prevalence of MetS in HS patients and revise the odds ratio of comorbid disease. Furthermore, we attempt to draw parallels between inflammatory pathways in HS and MetS and evaluate how convergences may explain the risk of comorbid disease, necessitating the need for multidisciplinary care.

Omentin attenuates angiotensin II-induced abdominal aortic aneurysm formation in apolipoprotein-E knockout mice

AIMS

Abdominal aortic aneurysm (AAA) is an increasing and life-threatening disease. Obesity contributes to an increased risk of AAA. Omentin is a circulating adipokine, which is downregulated in obese complications. Here we examined whether omentin could modulate angiotensin (Ang) II-induced AAA formation in apolipoprotein-E knockout (apoE-KO) mice.

METHODS AND RESULTS

ApoE-KO mice were crossed with transgenic mice expressing the human omentin gene in fat tissue (OMT-Tg mice) to generate ApoE-KO/OMT-Tg mice. ApoE-KO/OMT-Tg and apoE-KO mice were subjected to continuous Ang II infusion by using osmotic mini pumps. ApoE-KO/OMT-Tg mice exhibited a lower incidence of AAA formation and a reduced maximal diameter of AAA compared with apo-E KO mice. ApoE-KO/OMT-Tg mice showed attenuated disruption of medial elastic fibers in response to Ang II compared with apo-E KO mice. ApoE-KO/OMT-Tg mice also displayed reduced expression levels of matrix metalloproteinase (MMP) 9, MMP2 and pro-inflammatory genes in aortic walls compared with apo-E KO mice. Furthermore, systemic administration of omentin also attenuated AAA formation and disruption of medial elastic fibers in response to Ang II in apoE-KO mice. Treatment of human monocyte-derived macrophages with omentin protein attenuated expression of MMP9 and pro-inflammatory mediators, and MMP9 activation after stimulation with lipopolysaccharide (LPS). Treatment of human vascular smooth muscle cells with omentin protein reduced expression and activation of MMP2 after stimulation with tumor necrosis factor α. Omentin treatment increased phosphorylation levels of Akt in human macrophages and vascular smooth muscle cells. The suppressive effects of omentin on MMP9 and MMP2 expression were reversed by inhibition of integrin-αVβ3/PI3-kinase/Akt signaling in macrophages and vascular smooth muscle cells, respectively.

CONCLUSION

These data suggest that omentin acts as an adipokine that can attenuate Ang II-induced development of AAA through suppression of MMP9 and MMP2 expression and inflammatory response in the vascular wall.

Omentin: A novel therapeutic approach for the treatment of endothelial dysfunction in type 2 diabetes

BACKGROUND

Perivascular adipose tissue (PVAT) locally influences the functioning of blood vessels and promotes vascular complications associated with diabetes and obesity. The aim of this work was to study the impact of omentin-1 on endothelial function and PVAT in a non-obese type 2 diabetes mellitus animal model, Goto-Kakizaki (GK) rats with or without high fat diet.

MATERIAL AND METHODS

Diabetic GK rats were divided into four groups: 1) control group; 2) group treated with omentin-1; 3) group of GK rats fed a high fat diet (GKHFD) and 4) group of GKHFD treated with omentin-1. Several in vivo parameters such as adiposity and Lee indexes, lipid profile, fasting glucose levels, glucose and insulin tolerance tests were determined. At the vascular level, endothelial dependent and independent relaxation and contraction studies were performed in aortic rings in the absence (PVAT-) or in the presence (PVAT+) of thoracic PVAT. We also evaluated vascular oxidative stress and determined the pro-inflammatory status of PVAT.

RESULTS

Endothelium-dependent relaxation to acetylcholine, assessed by wire myography, was impaired in GK and GKHFD rats and improved by the omentin-1 treatment. In addition, vascular superoxide production was increased in the vascular wall of diabetic rats, accompanied by reduced nitric oxide bioavailability and significantly improved by omentin treatment. PVAT anti-contractile action found under physiological conditions was lost in type 2 diabetes, and partially recovered with omentin-1 administration. In addition, omentin-1 treatment significantly improved proinflammatory and pro-oxidant PVAT phenotype (decreasing C-reactive protein and nitrotyrosine levels). Furthermore, it was observed an improvement in various systemic and metabolic biochemical parameters of diabetic animals treated for one month with omentin.

CONCLUSIONS

Omentin-1 ameliorates endothelial dysfunction in type 2 diabetes and presents therapeutic potential for the treatment of vascular complications associated with type 2 diabetes.

The effects of physical activity on adipokines in individuals with overweight/obesity across the lifespan: A narrative review

This narrative review summarizes current knowledge on the effects of physical activity (PA) on adipokine levels in individuals with overweight and obesity. Approximately 90 investigations including randomized control, cross-sectional and longitudinal studies that reported on the effects of a single session of PA (acute) or long-term PA (chronic) on adipokine levels in individuals with overweight/obesity were reviewed. The findings support the notion that there is consensus on the benefits of chronic exercise training-regardless of the mode (resistance vs. aerobic), intensity and cohort (healthy vs. diabetes)-on adipokine levels (such as tumour necrosis factor-alpha, interleukin-6, adiponectin, visfatin, omentin-1 and leptin). However, several confounding factors (frequency, intensity, time and type of exercise) can alter the magnitude of the effects of an acute exercise session. Available evidence suggests that PA, as a part of routine lifestyle behaviour, improves obesity complications by modulating adipokine levels. However, additional research is needed to help identify the most effective interventions to elicit the most beneficial changes in adipokine levels in individuals with overweight/obesity.

Association between Omentin-1 and Coronary Artery Disease: Pathogenesis and Clinical Research

Like other adipokines, omentin-1 is secreted from visceral adipose tissue and plays a vital role in the development of chronic inflammatory diseases, including cardiovascular events. Recent studies have shown that circulating omentin-1 levels are associated with various metabolic risk factors, such as high blood pressure, increased waist circumference, dyslipidemia, and glucose intolerance. The decrease in serum omentin level is an independent predictor of Coronary Artery Disease (CAD) and is associated with the severity of this disease. Since there is no relevant review in the literature, we aimed to summarize the studies on the relationship between omentin-1 and CAD.

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.

Adipose Tissue Distribution, Inflammation and Its Metabolic Consequences, Including Diabetes and Cardiovascular Disease

Adipose tissue plays essential roles in maintaining lipid and glucose homeostasis. To date several types of adipose tissue have been identified, namely white, brown, and beige, that reside in various specific anatomical locations throughout the body. The cellular composition, secretome, and location of these adipose depots define their function in health and metabolic disease. In obesity, adipose tissue becomes dysfunctional, promoting a pro-inflammatory, hyperlipidemic and insulin resistant environment that contributes to type 2 diabetes mellitus (T2DM). Concurrently, similar features that result from adipose tissue dysfunction also promote cardiovascular disease (CVD) by mechanisms that can be augmented by T2DM. The mechanisms by which dysfunctional adipose tissue simultaneously promote T2DM and CVD, focusing on adipose tissue depot-specific adipokines, inflammatory profiles, and metabolism, will be the focus of this review. The impact that various T2DM and CVD treatment strategies have on adipose tissue function and body weight also will be discussed.

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.

Impact of serum omentin-1 concentrations on functional outcome among acute intracerebral hemorrhage patients

BACKGROUND

Reduced serum omentin-1 concentrations might be related to an increased risk for poor functional outcome after acute ischemic stroke. We intended to explore whether serum omentin-1 could be a promising prognostic biomarker for acute intracerebral hemorrhage.

METHODS

A total of 104 consecutive patients with hemorrhagic stroke underwent 90-day follow-up. The modified Rankin scale score >2 was evaluated as worse prognosis. A multivariable logistic model was conFig.d for assessing the relationship between serum omentin-1 concentrations and functional outcome.

RESULTS

Serum omentin-1 concentrations, with the median value of 147.9 ng/ml (interquartile range, 114.7-199.8 ng/ml), were substantially declined with rising modified Rankin scale scores (P < 0.001). Serum omentin-1 concentrations <147.9 ng/ml was independently related to higher risk of 90-day worse prognosis (odds ratio, 3.789; 95% confidence interval, 1.819-8.608; P = 0.018). Under receiver operating characteristic curve, an optimal value of serum omentin-1 concentrations was selected as 179.7 ng/ml, which yielded 0.88 sensitivity value and 0.70 specificity value for discriminating patients at risk of 90-day worse prognosis (area under curve, 0.82; 95% confidence interval, 0.73-0.89).

CONCLUSIONS

Lower serum omentin-1 concentrations are closely associated with poor functional outcome after hemorrhagic stroke, substantializing serum omentin-1 as a potential prognostic biomarker for acute intracerebral hemorrhage.

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.

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.

Evaluation of the Association of Omentin 1 rs2274907 A>T and rs2274908 G>A Gene Polymorphisms with Coronary Artery Disease in Indian Population: A Case Control Study

Coronary artery disease (CAD) is a major cause of death all over the world. CAD is caused by atherosclerosis which is induced by the interaction of genetic factors and environmental factors. Traditional environmental risk factors include hyperlipidemia, diabetes mellitus, lack of exercise, obesity, poor diet and others. Genome-wide association studies have revealed the association of certain gene polymorphisms with susceptibility to CAD. Omentin 1 is an adipokine secreted by the visceral adipose tissues and has been reported to have anti-inflammatory, cardioprotective, and enhances insulin sensitivity. In this study, we examined the role of omentin-1 common single nucleotide polymorphisms (SNPs) (rs2274907 A>T and rs2274908 G>A) in CAD. We genotyped 100 CAD patients and 100 matched healthy controls from the south Indian population using an amplification refractory mutation system (ARMS-PCR) and allele-specific PCR (AS-PCR). Our result indicated the rs2274908 G>A is not associated with CAD. Results showed that there was a significant difference in rs2274907 A>T genotype distribution between controls and CAD cases (P-value < 0.05). Results indicated that the AT genotype of the rs2274907 is associated with CAD with OR = 3.0 (95% confidence interval (CI), 1.64 to 5.49), 1.65 (1.27 to 2.163), P = 0.002. The T allele of the rs2274907 was also associated with CAD with OR = 1.82 (95% CI, 1.193 to 2.80), 1.37 (1.08 to 1.74), P = 0.005. Rs2274907 genotype distribution was also correlated with serum total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), hypertension and diabetes. We conclude that the AT genotype and the T allele of the rs2274907 A>T is associated with Cad in the south Indian population. Further studies on the effect of the rs2274907 A>T on omentin-1 function are recommended, and future well-designed studies with larger sample sizes and in different populations are required to validate our findings.

Impact of serum omentin-1 levels on functional prognosis in nondiabetic patients with ischemic stroke

OBJECTIVE

Omentin-1, an adipokine released from visceral fat tissue, is associated with diabetes and stroke. The purpose of this study was to assess the impact of serum omentin-1 levels on functional prognosis in nondiabetic patients with ischemic stroke.

METHODS

From March 2016 to December 2017, consecutive patients with first-ever ischemic stroke admitted to our hospital, China, were recorded. Functional impairment was evaluated at 3-month after admission using the modified Rankin scale (mRS). Uni-and multivariate analyses with Cox proportional hazard regression was used for assessing the relationship between serum level of omentin-1 and functional outcome.

RESULTS

We recorded 209 stroke patients, 52 of them (24.9%) experienced as poor functional outcome. The obtained omentin-1 level in patients with poor outcome was lower than in those patients with good outcome [100.8 (80.9-131.6) ng/ml vs. 137.6 (IQR, 106.1-171.5) ng/ml; Z=4.692; P<0.001). Multivariate analysis models were used to assess stroke outcome according to omentin-1 quartiles (the highest quartile [Q4] as the reference), the 1^st and 2^nd quartile of omentin-1 were compared against the Q4, and the risks were increased by 505% (HR=6.05; 95% CI: 2.13-12.15; P=0.007) and 215% (31.5; 1.21-7.98; P=0.03), respectively. The inclusion of omentin-1 in the routine prediction model for the prediction of poor functional outcome, enhanced the NRI (P=0.006) and IDI (P=0.001) values, confirming the effective reclassification and discrimination. Kaplan-Meier analysis suggested that the patients with low serum omentin-1 levels had a higher risk of death than those patients with high levels of omentin-1 (log-rank test P=0.033).

CONCLUSION

In this cohort of nondiabetic patients with ischemic stroke, a reduced baseline level of serum omentin-1 was related with an increased risk for poor functional outcome or death, independent of baseline variables.

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.

The association between resting metabolic rate and metabolic syndrome May Be mediated by adipokines in overweight and obese women

AIMS

Adipokines play a major role in developing metabolic syndrome (MetS), and it has been found that there is a significant relationship between MetS and resting metabolic rate (RMR) in obese people. The present study aimed to investigate the mediatory effect of adipokines on the RMR-MetS relationship.

METHODS

This cross-sectional study included 263 obese and overweight women, mean BMI 33.28 (4.93) kg/m, and mean age 39.02 (11.60) who were assessed for RMR using indirect calorimetry. Moreover, using the body composition analyzer the Body composition was measured. Also, Enzyme-linked Immunosorbent Assay (ELISA) test provided a quantitative measurement of biochemical parameters.

RESULTS

The results indicated that women in low RMR group had higher fat mass (P < 0.0001), FFM (P = 0.002), weight (P = 0.006), BMI (P < 0.0001), age (P = 0.01), and hs-CRP (P = 0.001). The results did not confirm any significant mediating roles for RBP4 (P = 0.051, β = -0.28) and Vaspin (P = 0.06, β = 0.32) in the RMR-MetS relationship. Additionally, after a binary regression test, Omentin-1 showed a significant mediating role (P = 0.25, β = 0.04) as an interrelated agent to RMR and MetS.

CONCLUSION

As this study shows, Omentin-1 was found to play a significant mediating role as a mediatory agent in relationship between RMR and MetS.

The Impact of Aging on Adipose Function and Adipokine Synthesis

During the last 40 years, there has been a world-wide increase in both the prevalence of obesity and an increase in the number of persons over the age of 60 due to a decline in deaths from infectious disease and the nutrition transition in low and middle income nations. While the increase in the elderly population indicates improvements in global public health, this population may experience a diminished quality of life due to the negative impacts of obesity on age-associated inflammation. Aging alters adipose tissue composition and function resulting in insulin resistance and ectopic lipid storage. A reduction in brown adipose tissue activity, declining sex hormones levels, and abdominal adipose tissue expansion occur with advancing years through the redistribution of lipids from the subcutaneous to the visceral fat compartment. These changes in adipose tissue function and distribution influence the secretion of adipose tissue derived hormones, or adipokines, that promote a chronic state of low-grade systemic inflammation. Ultimately, obesity accelerates aging by enhancing inflammation and increasing the risk of age-associated diseases. The focus of this review is the impact of aging on adipose tissue distribution and function and how these effects influence the elaboration of pro and anti-inflammatory adipokines.

Classic and Novel Adipocytokines at the Intersection of Obesity and Cancer: Diagnostic and Therapeutic Strategies

PURPOSE OF REVIEW

In this review, we investigate the role of classic and novel adipocytokines in cancer pathogenesis synopsizing the mechanisms underlying the association between adipocytokines and malignancy. Special emphasis is given on novel adipocytokines as new evidence is emerging regarding their entanglement in neoplastic development.

RECENT FINDINGS

Recent data have emphasized the role of the triad of overweight/obesity, insulin resistance and adipocytokines in cancer. In the setting of obesity, classic and novel adipocytokines present independent and joint effects on activation of major intracellular signaling pathways implicated in cell proliferation, expansion, survival, adhesion, invasion, and metastasis. Until now, more than 15 adipocytokines have been associated with cancer, and this list continues to expand. While the plethora of circulating pro-inflammatory adipocytokines, such as leptin, resistin, extracellular nicotinamide phosphoribosyl transferase, and chemerin are elevated in malignancies, some adipocytokines such as adiponectin and omentin-1 are generally decreased in cancers and are considered protective against carcinogenesis. Elucidating the intertwining of inflammation, cellular bioenergetics, and adiposopathy is significant for the development of preventive, diagnostic, and therapeutic strategies against cancer. Novel more effective and safe adipocytokine-centered therapeutic interventions may pave the way for targeted oncotherapy.

Changes in omentin levels and its mRNA expression in epicardial adipose tissue in patients undergoing elective cardiac surgery: the influence of type 2 diabetes and coronary heart disease

Omentin is a protein produced by numerous tissues including adipose tissue. Its concentrations are decreased in patients with obesity, type 2 diabetes mellitus (DM) and coronary artery disease (CAD). Experimental studies suggest that omentin may have anti-inflammatory and insulin-sensitizing properties. In the present study, we measured circulating omentin levels and its mRNA expression in epicardial and subcutaneous fat, intercostal and heart muscle before and after elective cardiac surgery in patients with CAD (CAD+, DM-, n=18), combination of CAD and DM (CAD+, DM+, n=9) or with none of these conditions (CAD-, DM-, n=11). The groups did not differ in baseline anthropometric and biochemical characteristics with the exception of higher blood glucose and HBA(1c) in CAD+, DM+ group. Baseline circulating omentin levels tended to be lower in CAD+, DM- and CAD+, DM+ groups as compared to CAD-, DM- group and cardiac surgery increased its concentration only in CAD-, DM- group. The change in serum omentin levels during surgery inversely correlated with epicardial fat thickness. While baseline omentin mRNA expression did not differ among the groups in any of the studied tissues, its increase after surgery was present only in subcutaneous fat in CAD-, DM- and CAD+, DM- groups, but not in CAD+, DM+ group. Intercostal muscle omentin mRNA expression increased after surgery only in CAD-, DM- group. In conclusion, cardiac surgery differentially affects omentin levels and subcutaneous fat and skeletal muscle mRNA expression in patients without coronary artery disease and diabetes as compared to patients with these conditions.

Adiponectin, Omentin, Ghrelin, and Visfatin Levels in Obese Patients with Severe Obstructive Sleep Apnea

Objectives

Obstructive sleep apnea (OSA) is closely associated with obesity, insulin resistance, and inflammation. Adiponectin, omentin, ghrelin, and visfatin are adipokines involved in insulin sensitivity or regulation of inflammatory disease. This study aims to clarify the relationship between OSA and associated adipokines.

Patients and Methods

Thirty overweight male patients with severe OSA and twenty controls underwent standard diagnostic polysomnography (PSG), and 10 patients underwent overnight continuous positive airway pressure (CPAP) treatment. Blood samples were collected in the morning after PSG or CPAP procedures.

Results

Among the investigated adipokines, only plasma omentin levels of patients with OSA were significantly lower than those of control subjects (442.94 ± 191.89 ng/ml versus 573.52±228.67 ng/ml, p=0.034) and levels did not change after CPAP treatment. In patients with OSA, omentin levels were positively correlated with high-density lipoprotein cholesterol (HDL) levels (r=0.378, p=0.007), adiponectin levels (r=0.709, p<0.001), percentage of sleep at the rapid eye movement (REM) stage (r=0.307, p=0.003), and average and minimum SpO₂ (p=0.041, 0.046, respectively) and negatively with hypersensitive C-reactive protein (hsCRP, r=-0.379, p=0.007) and apnea-hypopnea index (AHI, r=-0.315, p=0.026). However, plasma concentrations of adiponectin, ghrelin, and visfatin in patients with OSA did not significantly differ from those of the control or correlate with sleep parameters and CPAP treatment.

Conclusions

Patients with OSA have decreased omentin levels, which are associated with sleep parameters, including AHI, SpO₂, percentage of REM sleep, hsCRP, HDL, and adiponectin levels.

Population-based serum omentin-1 levels: paradoxical association with cardiometabolic disorders primarily in men

AIM

The conflicting relationships of serum omentin with inflammation markers and cardiometabolic disorders were investigated. Results & methods: Unselected 864 population-based middle-aged adults were cross-sectionally studied by sex-specific omentin tertiles. Men in the lowest omentin tertile (T1) had lower systolic blood pressure, HbA1c and glucose values and tended in T3 to higher lipoprotein(a) levels. Logistic regression analysis, adjusted for four covariates, revealed significant independent associations with the presence of hypertension and diabetes only in men. Sex- and age-adjusted odds ratio in gender combined for T2 & T3 versus T1 was 1.34 (95% CI: 1.00-1.79) for metabolic syndrome.

DISCUSSION & CONCLUSION

The elicited adverse relationships of omentin-1 support the notion of oxidative stress-induced proinflammatory conversion of omentin, rendering loss of anti-inflammatory properties.

Serum levels of omentin-1 are increased after weight loss and are particularly associated with increases in obese children with metabolic syndrome

AIM

There have been very few paediatric studies on omentin-1, an anti-inflammatory adipokine that provides a link between adiposity, insulin resistance and metabolic syndrome. This Chinese study evaluated the association between omentin-1 and metabolic syndrome and analysed the effect of a six-month lifestyle intervention on the levels in obese children.

METHODS

We recruited 119 obese outpatients (75% boys) aged 7-18 years from the Second Affiliated Hospital of Xi'an Jiaotong University, who underwent a six- month lifestyle intervention. Our controls were 55 matched children with normal weight. Anthropometric parameters, biochemical data and circulating omentin-1 levels were measured at baseline and after six months.

RESULTS

Of the 119 obese children, 32 (27%) had metabolic syndrome. The obese children, particularly those with metabolic syndrome, had significantly lower serum omentin-1 levels at baseline than the controls. We also found that the omentin-1 levels were negatively associated with their body mass index, waist circumference and homoeostasis model assessment of insulin resistance. After the six-month lifestyle intervention, the obese children showed significant weight loss and their omentin-1 levels increased.

CONCLUSION

Serum omentin-1 was regulated by weight and seemed to be associated with children's metabolic disorders. A six-month lifestyle intervention significantly increased serum omentin-1 levels.

Melatonin Supplementation Lowers Oxidative Stress and Regulates Adipokines in Obese Patients on a Calorie-Restricted Diet

Obesity is one of the major global health problems. Melatonin deficiency has been demonstrated to correlate with obesity. The aim of the study was to estimate the effect of melatonin on oxidative stress and adipokine levels in obese patients on a calorie-restricted diet. Thirty obese patients were supplemented with a daily dose of 10 mg of melatonin (n = 15) or placebo (n = 15) for 30 days with a calorie-restricted diet. Serum levels of melatonin, 4-hydroxynonenal (HNE), adiponectin, omentin-1, leptin, and resistin, as well as erythrocytic malondialdehyde (MDA) concentration and Zn/Cu-superoxide dismutase, catalase, and glutathione peroxidase (GPx) activities, were measured at baseline and after supplementation. Significant body weight reduction was observed only in the melatonin group. After melatonin supplementation, the adiponectin and omentin-1 levels and GPx activities statistically increased, whereas the MDA concentrations were reduced. In the placebo group, a significant rise in the HNE and a drop in the melatonin concentrations were found. The results show evidence of increased oxidative stress accompanying calorie restriction. Melatonin supplementation facilitated body weight reduction, improved the antioxidant defense, and regulated adipokine secretion. The findings strongly suggest that melatonin should be considered in obesity management. This trial is registered with CTRI/2017/07/009093.

Adipose Tissue-Derived Omentin-1 Function and Regulation

Omentin-1, also known as intelectin-1, is a recently identified novel adipocytokine of 313 amino acids, which is expressed in visceral (omental and epicardial) fat as well as mesothelial cells, vascular cells, airway goblet cells, small intestine, colon, ovary, and plasma. The level of omentin-1 expression in (pre)adipocytes is decreased by glucose/insulin and stimulated by fibroblast growth factor-21 and dexamethasone. Several lines of experimental evidence have shown that omentin-1 plays crucial roles in the maintenance of body metabolism and insulin sensitivity, and has anti-inflammatory, anti-atherosclerotic, and cardiovascular protective effects via AMP-activated protein kinase/Akt/nuclear factor-κB/mitogen-activated protein kinase (ERK, JNK, and p38) signaling. Clinical studies have indicated the usage of circulating omentin-1 as a biomarker of obesity, metabolic disorders including insulin resistance, diabetes, and metabolic syndrome, and atherosclerotic cardiovascular diseases. It is also possible to use circulating omentin-1 as a biomarker of bone metabolism, inflammatory diseases, cancers, sleep apnea syndrome, preeclampsia, and polycystic ovary syndrome. Decreased omentin-1 levels are generally associated with these diseases. However, omentin-1 increases to counteract the acute phase after onset of these diseases. These findings indicate that omentin-1 may be a negative risk factor for these diseases, and also act as an acute-phase reactant by its anti-inflammatory and atheroprotective effects. Therapeutic strategies to restore omentin-1 levels may be valuable for the prevention or treatment of these diseases. Weight loss, olive oil-rich diet, aerobic training, and treatment with atorvastatin and antidiabetic drugs (metformin, pioglitazone, and exenatide) are effective means of increasing circulating omentin-1 levels. This review provides insights into the potential use of omentin-1 as a biomarker and therapeutic target for these diseases. © 2017 American Physiological Society. Compr Physiol 7:765-781, 2017.

Effect of Body Mass Index on Posttonsillectomy Hemorrhage

OBJECTIVE

Obesity affects adverse outcomes in patients undergoing various surgeries. Tonsillectomy is one of the most common surgical procedures and posttonsillectomy hemorrhage (PTH) is the major complication in patients with tonsillectomy. However, the effect of body mass index (BMI) on posttonsillectomy bleeding episodes is not well known. This study aimed to assess the clinical association between obesity and PTH.

METHODS

A total of 98 tonsillectomies were retrospectively reviewed. Patient charts were analyzed regarding demographic data and the indication for surgery. Patients with PTH were compared with uneventful cases. Patients were divided into three groups based on BMI: normal weight (BMI < 25 kg/m²), overweight (BMI ≥ 25 and <30 kg/m²), and obese (≥30 kg/m²).

RESULTS

PTH occurred in 13% of patients with normal weight, in 23.5% of patients with overweight, and in 50% patients with obesity. The occurrence of PTH was significantly higher in patients with obesity than in those with normal weight and overweight (p = 0.008). Multivariate analysis showed that obesity was a significant factor affecting the incidence of PTH after adjusting for confounding factors.

CONCLUSIONS

Our findings suggest that the obese condition is independently associated with the incidence of PTH.

Obesity-Induced Changes in Adipose Tissue Microenvironment and Their Impact on Cardiovascular Disease

Obesity is causally linked with the development of cardiovascular disorders. Accumulating evidence indicates that cardiovascular disease is the collateral damage of obesity-driven adipose tissue dysfunction that promotes a chronic inflammatory state within the organism. Adipose tissues secrete bioactive substances, referred to as adipokines, which largely function as modulators of inflammation. The microenvironment of adipose tissue will affect the adipokine secretome, having actions on remote tissues. Obesity typically leads to the upregulation of proinflammatory adipokines and the downregulation of anti-inflammatory adipokines, thereby contributing to the pathogenesis of cardiovascular diseases. In this review, we focus on the microenvironment of adipose tissue and how it influences cardiovascular disorders, including atherosclerosis and ischemic heart diseases, through the systemic actions of adipokines.

Serum omentin and vaspin levels in cirrhotic patients with and without portal vein thrombosis

AIM

To investigate serum omentin and vaspin levels in cirrhotic patients; and to assess the relationship of these levels with hemostatic parameters, metabolic abnormalities, cirrhosis severity and etiology.

METHODS

Fifty-one cirrhotic patients (17 with portal vein thrombosis) were analyzed. Serum omentin and vaspin levels were measured with commercially available direct enzyme-linked immunosorbent assays (ELISAs). To assess platelet activity, the following tests were performed using a MULTIPLATE^®PLATELET FUNCTION ANALYZER: (1) an ADP-induced platelet activation test; (2) a cyclooxygenase dependent aggregation test (ASPI test); (3) a von Willebrand factor and glycoprotein Ib-dependent aggregation (using ristocetin) test (RISTO test); and (4) a test for thrombin receptor-activating peptide-6 induced activation of the thrombin receptor, which is sensitive to IIb/IIIa receptor antagonists.

RESULTS

Omentin, but not vaspin, serum concentrations were significantly decreased in patients with portal vein thrombosis (PVT) (P = 0.01). Prothrombin levels were significantly increased in patients with PVT (P = 0.01). The thrombin receptor activating peptide (TRAP) test results were significantly lower in the PVT group (P = 0.03). No significant differences in adipokines serum levels were found regarding the etiology or severity of liver cirrhosis assessed according to the Child-Pugh or Model of End-Stage Liver Disease (MELD) scores. There was a significant increase in the TRAP (P = 0.03), ASPI (P = 0.001) and RISTO high-test (P = 0.02) results in patients with lower MELD scores. Serum omentin and vaspin levels were significantly down-regulated in patients without insulin resistance (P = 0.03, P = 0.02, respectively). A positive relationship between omentin and vaspin levels were found both when all of the patients were analyzed (r = 0.41, P = 0.01) and among those with PVT (r = 0.94, P < 0.001).

CONCLUSION

Serum omentin levels are increased in patients without PVT. Cirrhosis origin and grade do not affect omentin and vaspin levels. The analyzed adipokines do not influence platelet activity.

Levels of metabolic markers in drug-naive prediabetic and type 2 diabetic patients

AIMS

Type 2 diabetes mellitus (T2DM) and prediabetes (pre-DM) are associated with changes in levels of metabolic markers. The main aim of this study is to compare the levels of omentin, irisin, endothelin-1, nesfatin, hepatocyte growth factor (HGF), fibroblast growth factor, and oxytocin (OXT) between normoglycemic and pre-DM/T2DM obese Jordanian patients.

METHODS

One hundred and ninety-eight adult Jordanian subjects were recruited. Demographic data and clinical parameters were collected. The serum levels of biomarkers were measured by enzymatic assay procedure.

RESULTS

Compared to normoglycemic (95 subjects), pre-DM/T2DM (103 subjects) displayed higher HGF (ng/ml) = 78.8 (71.4-104) versus 55.9 (45.3-66.6), p < 0.0001; and nesfatin (ng/ml) = 0.5 (0.4-0.7) versus 0.2 (0.1-0.4), p < 0.0001; betatrophin (ng/ml) = 1.2 (0.8-1.6) versus 0.22 (0.15-0.41), p < 0.0001. On the other hand, they had lower levels of omentin (ng/ml) = 2.1 (0.9-3.3) versus 3.6 (2.0-6.4), p < 0.0001, irisin (ng/ml) = 113.7 (88.9-142.9) versus 132.6 (110.7-147.8), p < 0.0001; and oxytocin (pg/ml) = 1077.9 (667.3-1506.0) versus 2180.1 (1464.5-2795.6), p < 0.0001; respectively. In comparison, FGF-21 (ng/ml) = 0.3 (0.2-0.5) versus 0.2 (0.1-0.4), and endothelin (pg/ml) = 2.7 (1.3-5.2) versus 2.8 (1.6-5.6) did not differ between the two groups (p > 0.05).

CONCLUSIONS

In the present study, patients with pre-DM and T2DM have higher serum levels of metabolic HGF, nesfatin, and betatrophin and lower levels of omentin, irisin, and OXT. Future longitudinal and interventional studies are required to confirm the utility of these markers as novel progression or therapeutic targets in the pharmacotherapy of diabetes.