Implication of circulating omentin-1 level on the arterial stiffening in type 2 diabetes mellitus

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.

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.

Adipokines and Arterial Stiffness in Obesity

Adipokines are active molecules with pleiotropic effects produced by adipose tissue and involved in obesity-related metabolic and cardiovascular diseases. Arterial stiffness, which is a consequence of arteriosclerosis, has been shown to be an independent predictor of cardiovascular morbidity and mortality. The pathogenesis of arterial stiffness is complex but incompletely understood. Adipokines dysregulation may induce, by various mechanisms, vascular inflammation, endothelial dysfunction, and vascular remodeling, leading to increased arterial stiffness. This article summarizes literature data regarding adipokine-related pathogenetic mechanisms involved in the development of arterial stiffness, particularly in obesity, as well as the results of clinical and epidemiological studies which investigated the relationship between adipokines and arterial stiffness.

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.

Association between omentin-1 and major cardiovascular events after lower extremity endovascular revascularization in diabetic patients: a prospective cohort study

Background

Cardiovascular complications represent the major cause of morbidity and mortality of type 2 diabetes mellitus (T2DM) patients. In particular, peripheral artery disease (PAD) represents a frequent T2DM vascular complication and a risk factor for the development of major adverse cardiovascular events (MACE). Among adipokines, omentin-1 serum levels are reduced in T2DM patients with PAD and are inversely related to disease severity.

Objective

To study the relationship between omentin-1 levels, at baseline, with outcomes after endovascular procedures in T2DM patients with PAD and chronic limb-threatening ischemia (CLTI).

Research design and methods

We enrolled for our prospective non-randomized study, 207 T2DM patients with PAD and CLTI, requiring revascularization. Omentin-1 serum levels were collected before revascularization and patients incidence outcomes were evaluated at 1, 3, 6 and 12 months.

Results

Omentin-1 was reduced in patients with more severe disease (27.24 ± 4.83 vs 30.82 ± 5.48 ng/mL, p < 0.001). Overall, 84 MACE and 96 major adverse limb events (MALE) occurred during the 12-month follow-up. We observed that omentin-1 levels were lower in patients with MACE (26.02 ± 4.05 vs 31.33 ± 5.29 ng/mL, p < 0.001) and MALE (26.67 ± 4.21 vs 31.34 ± 5.54 ng/mL, p < 0.001). The association between omentin-1, MACE and MALE remained significant after adjusting for major risk factors in a multivariate analysis. Receiver operating characteristics (ROC) curve using omentin-1 levels predicted incidence events (area under the curve = 0.80).

Conclusions

We demonstrated that reduced omentin-1 levels, at baseline, are related with worse vascular outcomes in T2DM patients with PAD and CLTI undergoing an endovascular procedure.

Clinical relevance of serum omentin-1 levels as a biomarker of prognosis in patients with acute cerebral infarction

BACKGROUND AND PURPOSE

Previous studies have shown that adipocytokines are associated with atherosclerosis, diagnosis, and functional prognosis after ischemic stroke. However, few studies have investigated the relationship between omentin-1 and atherosclerotic acute cerebral infarction (ACI).

METHODS

In this study, we investigated the association between serum omentin-1 levels at admission and severity, infarction volume, and functional prognosis of patients 90 days after atherosclerotic ACI.

RESULTS

A total of 109 patients with atherosclerotic ACI were enrolled. Serum omentin-1 levels at admission were lower in patients with ACI than those in healthy controls (47.18 ± 13.64 vs. 56.27 ± 34.44 ng/ml, p = .014). Serum omentin-1 levels at admission were negatively correlated with severity of ACI (r = -.271, p = .004) and infarction volume (r = -.264, p = .006), respectively. Moreover, serum omentin-1 levels were lower in the poor functional prognosis group than those in the good functional prognosis group in patients with large artery and small artery atherosclerotic ACI. In a logistic regression analysis, higher serum omentin-1 level (>43.10 ng/ml) at admission was negatively associated with a poor functional prognosis 90 days after atherosclerotic ACI.

CONCLUSIONS

Serum omentin-1 levels at admission were significantly lower among patients with ACI. A higher plasma omentin-1 level (>43.10 ng/ml) was negatively associated with poor functional prognosis 90 days after atherosclerotic ACI. Further studies are needed to investigate the pathophysiological mechanism of omentin-1 in affecting attacks and prognosis of ACI as well as to confirm the value of plasma omentin-1 level as a potential biomarker.

New Insights into Adipokines as Potential Biomarkers for Type-2 Diabetes Mellitus

A large number of studies have been focused on investigating serum biomarkers associated with risk or diagnosis of type-2 diabetes mellitus. In the last decade, promising studies have shown that circulating levels of adipokines could be used as a relevant biomarker for diabetes mellitus progression as well as therapeutic future targets. Here, we discuss the possible use of recently described adipokines, including apelin, omentin-1, resistin, FGF-21, neuregulin-4 and visfatin, as early biomarkers for diabetes. In addition, we also include recent findings of other well known adipokines such as leptin and adiponectin. In conclusion, further studies are needed to clarify the pathophysiological significance and clinical value of these biological factors as potential biomarkers in type-2 diabetes and related dysfunctions.

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.

Insights into the molecular mechanisms of diabetes-induced endothelial dysfunction: focus on oxidative stress and endothelial progenitor cells

Diabetes mellitus is a heterogeneous, multifactorial, chronic disease characterized by hyperglycemia owing to insulin insufficiency and insulin resistance (IR). Recent epidemiological studies showed that the diabetes epidemic affects 382 million people worldwide in 2013, and this figure is expected to be 600 million people by 2035. Diabetes is associated with microvascular and macrovascular complications resulting in accelerated endothelial dysfunction (ED), atherosclerosis, and cardiovascular disease (CVD). Unfortunately, the complex pathophysiology of diabetic cardiovascular damage is not fully understood. Therefore, there is a clear need to better understand the molecular pathophysiology of ED in diabetes, and consequently, better treatment options and novel efficacious therapies could be identified. In the light of recent extensive research, we re-investigate the association between diabetes-associated metabolic disturbances (IR, subclinical inflammation, dyslipidemia, hyperglycemia, dysregulated production of adipokines, defective incretin and gut hormones production/action, and oxidative stress) and ED, focusing on oxidative stress and endothelial progenitor cells (EPCs). In addition, we re-emphasize that oxidative stress is the final common pathway that transduces signals from other conditions-either directly or indirectly-leading to ED and CVD.

Association of serum omentin levels with cardiac autonomic neuropathy in patients with type 2 diabetes mellitus: a hospital-based study

Background

Whereas a few studies have reported associations of serum omentin levels with subclinical atherosclerosis in patients with diabetes, little information is available with respect to the associations of serum omentin levels and diabetic microvascular complications. The aim of this study was to investigate the relationships of serum omentin levels and vascular complications including cardiac autonomic neuropathy (CAN) in patients with type 2 diabetes mellitus (T2DM).

Methods

We recruited 97 patients who evaluated complications of diabetes. CAN was assessed by five standard cardiovascular reflex tests according to Ewing’s protocol. Diabetic nephropathy (DN), retinopathy (DR), and peripheral neuropathy (DPN) were evaluated. Serum omentin levels were assessed by ELISA. Atherosclerotic burden was evaluated by measuring the brachial-ankle pulse wave velocity (baPWV) and ankle brachial index (ABI).

Results

The prevalence of CAN increased borderline significantly across the omentin tertiles (p = 0.05) and CAN point increased significantly and progressively across the omentin tertiles (p = 0.013). The prevalence of other microvascular complications (DPN, DN, and DR) did not differ among omentin tertiles. The mean levels of baPWV also increased significantly and progressively across the omentin tertiles (p = 0.002). Serum omentin levels were significantly positively correlated with CAN point (p = 0.004) and borderline significantly correlated with baPWV (p = 0.05) after multivariate adjustment. Regarding linear regression analysis for CAN point, univariate regression analysis demonstrated that CAN point associated with omentin, diastolic blood pressure (DBP) and hsCRP. Multiple regression analysis revealed that omentin levels, together DBP and baPWV correlated with CAN point. This present study suggests that serum omentin levels may be independently associate with CAN in patients with T2DM.

Serum and Vitreous Concentrations of Omentin-1 in Diabetic Retinopathy

Objective. Omentin, a new discovered adipokine, is implicated to inhibit inflammation. Inflammation is one important mechanism of diabetic retinopathy (DR). The purpose of this work was to evaluate serum and vitreous concentrations of omentin-1 in patients with diabetic retinopathy (DR). Methods. This study enrolled 204 diabetic patients (60 without DR, 49 with NPDR, and 95 with PDR) and 65 control subjects. Results. Serum and vitreous omentin-1 levels in PDR patients were markedly decreased compared with those in the other three groups. NPDR patients showed reduced vitreous omentin-1 compared with patients without DR. In addition, control subjects had significantly higher levels of serum and vitreous omentin-1 compared with diabetic patients without DR, NPDR patients, and PDR patients. In addition, serum/vitreous omentin-1 ratio was positively correlated with the development and severity of DR. Conclusion. Serum and vitreous omentin-1 levels, as well as serum/vitreous omentin-1 ratio, are correlated with the presence and severity of DR.

The protective functions of omentin in cardiovascular diseases

Adipose tissue is considered as a large gland that can produce paracrine and endocrine hormones. Growing evidence suggests that adipocytes may link obesity to cardiovascular diseases (CVD). Adipose tissue produces a large number of mediators, which affect metabolism, inflammation and coagulation. Omentin, a novel adipocytokine, has come into the center of interest due to its favorable effects on inflammation, glucose homeostasis and CVD. The present review provides a concise and general overview on the roles of omentin in CVD. The knowledge of these concepts may provide a new strategy to reduce disease risks on CVD in the future.

Evaluation of body composition changes, epicardial adipose tissue, and serum omentin-1 levels in overt hypothyroidism

Our aim was to investigate body composition changes, epicardial adipose tissue thickness (EATT), serum omentin-1 levels, and the relationship among them along with some atherosclerosis markers in overt hypothyroidism. Twenty-eight newly diagnosed overt hypothyroid patients were evaluated before and after 6 months of thyroid hormone replacement therapy (THRT) and compared to the healthy subjects in this prospective longitudinal study. Body compositions were measured with dual-energy X-ray absorptiometry, and EATT was measured by echocardiography. Carotid intima-media thickness (c-IMT), flow-mediated dilatation (FMD), thyroid hormone levels, lipid parameters, high sensitive c-reactive protein, homocysteine, and omentin-1 levels were measured in all subjects. Body weight and lean body mass were higher in patients with hypothyroidism compared to euthyroid state after THRT (p = 0.012, 0.034, respectively). EATT was higher in patients with hypothyroidism than the control group (p < 0.001) and decreased with THRT (p = 0.012) but still remained higher than the control group (p < 0.001). Free T4 levels were found to be an independent factor to predict EATT (p < 0.001). In hypothyroid state, omentin-1 levels were lower than controls (p = 0.037) but increased in 6 months with THRT (p = 0.001). The c-IMT was higher, and FMD was lower in hypothyroidism compared to euthyroid state and control group (p < 0.05). Increasing lean body mass, but not adipose tissue mass, was found to be responsible for weight gain in hypothyroidism. The increased amount of EATT and decreased omentin-1 levels can contribute to the development of atherosclerosis in addition to other factors in hypothyroidism.

Circulating irisin, omentin-1, and lipoprotein subparticles in adults at higher cardiovascular risk

OBJECTIVE

Muscle and fat are now recognized as metabolism-regulating endocrine organs. However, muscle and adipocyte-derived novel cytokines such as irisin and omentin-1 remain understudied in relation to metabolic biomarkers that are associated with cardiovascular risk.

SUBJECTS AND METHODS

Thirty-nine subjects with mean (± SD) BMI of 29.2 ± 5.4 kg/m(2) and either diabetes or two other cardiovascular risk factors were enrolled in a 6-month randomized trial of low-dose ethanol. We examined cross-sectional data at baseline, 3-month, and 6-month visits to assess (1) within-person stability of novel cytokines (irisin, omentin-1, visfatin, resistin, and soluble tumor necrosis factor receptor II) and (2) their associations with metabolic parameters, particularly lipoprotein subparticle profile.

RESULTS

Repeated measures of irisin and omentin-1 were highly correlated, with intra-class correlations of 0.84 (95% CI: 0.74, 0.91; P < 0.001) and 0.81 (0.70, 0.89; P < 0.001), respectively. Irisin was negatively correlated with omentin-1 (7.4% irisin decrease per a 1-SD increment in omentin-1; 95% CI: 0.5%, 13.9%; P = 0.04). In models adjusted for age, sex, and race, irisin was negatively associated with HDL cholesterol (7.3% decrease per a 10mg/dL increment; 1.0%, 13.3%; P = 0.02) and large HDL particles (15.5% decrease per a 1-SD or 3.5-μmol/L increment; 5.2%, 24.7%; P=0.005). Omentin-1 was positively associated with mean VLDL size (3.8% increase per a 1-SD increment; 0.06%, 7.8%; P = 0.05). Adjustment for alcohol intervention, BMI, and other cytokines did not materially affect these associations.

CONCLUSIONS

Irisin and omentin-1 are stable within-person, inversely associated with each other, and closely related to lipoprotein profile. These molecules may be promising markers for cardiovascular risk.

Analysis of pericardial effusion from idiopathic pericarditis patients by two-dimensional gel electrophoresis

Pericardial fluid (PF) is often considered to be reflection of the serum by which information regarding the physiological status of the heart can be obtained. Some local and systemic disorders may perturb the balance between synthesis and discharge of PF and may cause its aberrant accumulation in the pericardial cavity as pericardial effusion (PE). PE may then lead to an increased intrapericardial pressure from which the heart function is undesirably affected. For some cases, the causes for the perturbance of fluid balance are well understood, but in some other cases, they are not apparent. It may, thus, be helpful to understand the molecular mechanisms behind this troublesome condition to elucidate a clinical approach for therapeutic uses. In this study, protein profiles of PEs from idiopathic pericarditis patients were analyzed. Control samples from patients undergoing elective cardiac surgery (ECS) were included for comparison. In addition to high abundant serum-originated proteins that may not hold significance for understanding the molecular mechanisms behind this disease, omentin-1 was identified and its level was higher for more than two-fold in PE of IP patients. Increased levels of omentin-1 in PE may open a way for understanding the molecular mechanisms behind idiopathic pericarditis (IP).