Counteractive effects of omentin-1 against atherogenesis†

The role of adipokines in the pathogenesis of psoriasis - a focus on resistin, omentin-1 and vaspin

BACKGROUND

Psoriasis is a chronic immune-mediated skin condition with several types of manifestation, including psoriatic arthritis. In recent years, studies have demonstrated multiple molecules and mechanisms that play important roles in the pathophysiology of psoriasis. Studies have been conducted to determine the role of adipokines, bioactive peptides secreted by the adipose tissue, in the pathogenesis of inflammatory diseases. These studies have shown that adipokines are dysregulated in psoriasis and their abnormal expression profile could contribute to the inflammatory mechanisms observed in psoriasis.

AREAS COVERED

In this review, we discuss the immunomodulatory features of resistin, omentin-1, and vaspin, and discuss their potential involvement in the pathogenesis of psoriasis.

EXPERT OPINION

The adipokines resistin, omentin, and vaspin appear to be promising therapeutic targets in psoriasis. It is important to seek to block the action of resistin, either by blocking its receptors or by blocking its systemic effects with antibodies. In the case of omentin and vaspin, substances that are receptor mimetics of these adipokines should be sought and studies conducted of their analogues for the treatment of psoriasis. To introduce these therapies into clinical practice, multicentre clinical trials are required to confirm their efficacy and safety after initial studies in animal models.

Human omentin-1 reduces vascular insulin resistance and hypertension in Otsuka Long-Evans Tokushima Fatty rats

PURPOSE

Hypertension is one of the major risk factors for renal failure and cardiovascular diseases, and is caused by various abnormalities including the contractility of blood vessels. Otsuka Long-Evans Tokushima Fatty (OLETF) rats, which mimic human type 2 diabetes, are frequently used to study obesity-induced insulin resistance (IR) and hypertension. Human omentin-1 is one of the recently identified adipocytokines. We previously demonstrated that human omentin-1 not only caused vasodilation in rat isolated blood vessels, but also prevented inflammatory responses, a possible mechanism relating IR, in human vascular endothelial cells. Taken together, we hypothesized that human omentin-1 may reduce obesity-induced IR and hypertension in OLETF rats.

METHODS

OLETF rats were intraperitoneally administered with human omentin-1 for 7 days.

RESULTS

Human omentin-1 had no influence on overweight, hyperglycemia, urinary glucose extraction, hyperinsulinemia, and systemic IR in OLETF rats. Human omentin-1 decreased systolic blood pressure in OLETF rats. The measurement of isometric contraction revealed that human omentin-1 had no influence on the agonist-induced contractile and relaxant responses in isolated thoracic aorta from OLETF rats. However, the relaxant response mediated by human insulin was converted into the contractile response in thoracic aorta from OLETF rats, which was prevented by human omentin-1. The Western blotting revealed that human omentin-1 improved the decrease in endothelial nitric oxide synthase activation in isolated thoracic aorta from OLETF rats.

CONCLUSION

In summary, we for the first time revealed that human omentin-1 partly reduces vascular IR and thereby inhibits hypertension in OLETF rats.

The Role of Epicardial Adipose Tissue in Acute Coronary Syndromes, Post-Infarct Remodeling and Cardiac Regeneration

Epicardial adipose tissue (EAT) is a fat deposit surrounding the heart and located under the visceral layer of the pericardium. Due to its unique features, the contribution of EAT to the pathogenesis of cardiovascular and metabolic disorders is extensively studied. Especially, EAT can be associated with the onset and development of coronary artery disease, myocardial infarction and post-infarct heart failure which all are significant problems for public health. In this article, we focus on the mechanisms of how EAT impacts acute coronary syndromes. Particular emphasis was placed on the role of inflammation and adipokines secreted by EAT. Moreover, we present how EAT affects the remodeling of the heart following myocardial infarction. We further review the role of EAT as a source of stem cells for cardiac regeneration. In addition, we describe the imaging assessment of EAT, its prognostic value, and its correlation with the clinical characteristics of patients.

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.

A Mediterranean Eating Pattern Combining Energy and Time-Restricted Eating Improves Vaspin and Omentin Concentrations Compared to Intermittent Fasting in Overweight Individuals

Athonian Orthodox fasting (AOF) is characterized by energy- and time-restricted eating (TRE) and is based on the Mediterranean diet. We aimed to investigate the impact of AOF compared to another TRE model on vaspin, omentin, nesfatin, and visfatin levels. We included 25 individuals (mean age 50.3 ± 8.6 years, 24% men) who practiced AOF and abstained from animal products, with the exception of seafood and fish. This group adopted a 12 h eating interval (08.00 to 20.00). In total, 12 participants (mean age 47.7 ± 8.7 years, 33.3% men) who practiced 16:8 TRE (eating from 09:00 to 17:00) and were allowed to consume meat served as the controls. Anthropometric and dietary data and adipokine levels were prospectively collected at three time points: at baseline, after the end of the diets (7 weeks), and 5 weeks after the participants returned to their typical eating habits (12 weeks from baseline). Vaspin levels decreased [795.8 (422.1-1299.4) (baseline) vs. 402.7 (203.8-818.9) (7 weeks) pg/mL, p = 0.002] and omentin levels increased [568.5 (437.7-1196.5) (baseline) vs. 659.0 (555.7-1810.8) (12 weeks) pg/mL, p = 0.001] in the AOF group, while none of the analyzed adipokines changed significantly in the TRE group. The variations observed in vaspin and omentin concentrations in the AOF group were independent of age, sex, changes in anthropometry and fat intake. In conclusion, AOF can significantly reduce vaspin and increase omentin, whose levels are known to increase and decrease, respectively, in obesity and type 2 diabetes. The implications of these findings for cardiometabolic health warrant further investigation.

Tanshinone IIA: a Chinese herbal ingredient for the treatment of atherosclerosis

Tanshinone IIA (Tan IIA) is a fat-soluble compound extracted from Salvia miltiorrhiza, which has a protective effect against atherosclerosis (AS). Tan IIA can inhibit oxidative stress and inflammatory damage of vascular endothelial cells (VECs) and improve endothelial cell dysfunction. Tan IIA also has a good protective effect on vascular smooth muscle cells (VSMCs). It can reduce vascular stenosis by inhibiting the proliferation and migration of vascular smooth muscle cells (VSMCs), and improve the stability of the fibrous cap of atherosclerotic plaque by inhibiting apoptosis and inflammation of VSMCs. In addition, Tan IIA inhibits the inflammatory response of macrophages and the formation of foam cells in atherosclerotic plaques. In summary, Tan IIA improves AS through a complex pathway. We propose to further study the specific molecular targets of Tan IIA using systems biology methods, so as to fundamentally elucidate the mechanism of Tan IIA. It is worth mentioning that there is a lack of high-quality evidence-based medical data on Tan IIA treatment of AS. We recommend that a randomized controlled clinical trial be conducted to evaluate the exact efficacy of Tan IIA in improving AS. Finally, sodium tanshinone IIA sulfonate (STS) can cause adverse drug reactions in some patients, which needs our attention.

Bioinformatics analysis identifies the protective targets of omentin in mice with focal cerebral ischemia injury

Omentin is known to play a protective role in ischemic stroke. However, its regulatory networks and downstream targets in the pathogenesis of IS are incompletely revealed now. In this study, the model of photochemical brain ischemia was constructed after omentin over-expression. 8 key differentially expressed genes (DEGs) were obtained and analyzed by transcriptome analysis. These DEGs were mainly related to the negative regulation of hormone secretion, cellular phosphate ion homeostasis, and other pathways. Moreover, the mRNA expression of predicted gene 3435 (Gm3435), ankyrin repeat domain 53 (Ankrd53), fibroblast growth factor 23 (Fgf23) and the Fgf23 protein expression were down-regulated after omentin over-expression in HT22 cells injured by oxygen-glucose deprivation (OGD). In conclusion, our findings identified 8 key DEGs regulated by omentin after IS. In vitro models, the Gm3435, Ankrd53, Fgf23 mRNA expression and the Fgf23 protein expression were further verified to consistent with the transcriptomics results.

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

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

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

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

Adipokines in atherosclerosis: unraveling complex roles

Adipokines are biologically active factors secreted by adipose tissue that act on local and distant tissues through autocrine, paracrine, and endocrine mechanisms. However, adipokines are believed to be involved in an increased risk of atherosclerosis. Classical adipokines include leptin, adiponectin, and ceramide, while newly identified adipokines include visceral adipose tissue-derived serpin, omentin, and asprosin. New evidence suggests that adipokines can play an essential role in atherosclerosis progression and regression. Here, we summarize the complex roles of various adipokines in atherosclerosis lesions. Representative protective adipokines include adiponectin and neuregulin 4; deteriorating adipokines include leptin, resistin, thrombospondin-1, and C1q/tumor necrosis factor-related protein 5; and adipokines with dual protective and deteriorating effects include C1q/tumor necrosis factor-related protein 1 and C1q/tumor necrosis factor-related protein 3; and adipose tissue-derived bioactive materials include sphingosine-1-phosphate, ceramide, and adipose tissue-derived exosomes. However, the role of a newly discovered adipokine, asprosin, in atherosclerosis remains unclear. This article reviews progress in the research on the effects of adipokines in atherosclerosis and how they may be regulated to halt its progression.

The Potency of Serum Omentin-1 Quantification in Predicting Major Adverse Cardiac and Cerebrovascular Events Risk in Patients Receiving Hemodialysis

Omentin-1 regulates inflammation, lipid accumulation, endothelial dysfunction, and atherosclerosis; the latter factors contribute to the occurrence of major adverse cardiac and cerebrovascular events (MACCE). This study aimed to explore the predictive implication of serum omentin-1 for MACCE risk in patients receiving hemodialysis. A total of 319 patients receiving hemodialysis and 160 healthy controls were prospectively enrolled in this study. Omentin-1 from serum was detected by enzyme-linked immunosorbent assay. MACCE was recorded during follow-up (median 18.9 months; range 1.9-62.9 months) in patients receiving hemodialysis. Omentin-1 was reduced in patients receiving hemodialysis versus healthy controls (P < 0.001). In patients receiving hemodialysis, omentin-1 was negatively related to C-reactive protein, total cholesterol, and low-density lipoprotein cholesterol (all P < 0.05); whereas omentin-1 was not related to other clinical characteristics. Notably, the 1-year, 2-year, 3-year, 4-year, and 5-year accumulating MACCE rates in patients receiving hemodialysis were 7.9%, 18.3%, 25.9%, 36.1%, and 41.4%, respectively. Interestingly, high omentin-1 related to decreased accumulating MACCE rate (P = 0.003), which was further validated by multivariate Cox regression analysis (hazard ratio = 0.458, P = 0.006). Additionally, by direct comparison, omentin-1 was reduced in hemodialysis patients who experienced MACCE compared to those who did not (P < 0.001); meanwhile, the receiver operator characteristic curve displayed that omentin-1 had an acceptable ability to estimate MACCE risk with an area under the curve (95% confidence interval) of 0.703 (0.628-0.777). Serum omentin-1 reflects reduced inflammation and lipid accumulation, as well as predicts decreased MACCE risk in patients receiving hemodialysis.

Omentin-1 drives cardiomyocyte cell cycle arrest and metabolic maturation by interacting with BMP7

Mammalian cardiomyocytes (CMs) undergo maturation during postnatal heart development to meet the increased demands of growth. Here, we found that omentin-1, an adipokine, facilitates CM cell cycle arrest and metabolic maturation. Deletion of omentin-1 causes mouse heart enlargement and dysfunction in adulthood and CM maturation retardation in juveniles, including delayed cell cycle arrest and reduced fatty acid oxidation. Through RNA sequencing, molecular docking analysis, and proximity ligation assays, we found that omentin-1 regulates CM maturation by interacting directly with bone morphogenetic protein 7 (BMP7). Omentin-1 prevents BMP7 from binding to activin type II receptor B (ActRIIB), subsequently decreasing the downstream pathways mothers against DPP homolog 1 (SMAD1)/Yes-associated protein (YAP) and p38 mitogen-activated protein kinase (p38 MAPK). In addition, omentin-1 is required and sufficient for the maturation of human embryonic stem cell-derived CMs. Together, our findings reveal that omentin-1 is a pro-maturation factor for CMs that is essential for postnatal heart development and cardiac function maintenance.

Development of a biomarker panel for assessing cardiovascular risk in diabetic patients with chronic limb-threatening ischemia (CLTI): a prospective study

BACKGROUND

Lower-extremity endovascular revascularization (LER) is often required for diabetic patients with chronic limb threatening ischemia (CLTI). During the post-revascularization period patients may unpredictably experience major adverse cardiac events (MACE) and major adverse limb events (MALE). Several families of cytokines are involved in the inflammatory process that underlies the progression of atherosclerosis. According to current evidence, we have identified a panel of possible biomarkers related with the risk of developing MACE and MALE after LER. The aim was to study the relationship between a panel of biomarkers - Interleukin-1 (IL-1) and 6 (IL-6), C-Reactive Protein (CRP), Tumor Necrosis Factor-α (TNF-α), High-Mobility Group Box-1 (HMGB-1), Osteoprotegerin (OPG), Sortilin and Omentin-1- at baseline, with cardiovascular outcomes (MACE and MALE) after LER in diabetic patients with CLTI.

METHODS

In this prospective non-randomized study, 264 diabetic patients with CLTI undergoing endovascular revascularization were enrolled. Serum levels of each biomarker were collected before revascularization and outcomes' incidence was evaluated after 1, 3, 6 and 12 months.

RESULTS

During the follow-up period, 42 cases of MACE and 81 cases of MALE occurred. There was a linear association for each biomarker at baseline and incident MACE and MALE, except Omentin-1 levels that were inversely related to the presence of MACE or MALE. After adjusting for traditional cardiovascular risk factors, the association between each biomarker baseline level and outcomes remained significant in multivariable analysis. Receiver operating characteristics (ROC) models were constructed using traditional clinical and laboratory risk factors and the inclusion of biomarkers significantly improved the prediction of incident events.

CONCLUSIONS

Elevated IL-1, IL-6, CRP, TNF-α, HMGB-1, OPG and Sortilin levels and low Omentin-1 levels at baseline correlate with worse vascular outcomes in diabetic patients with CLTI undergoing LER. Assessment of the inflammatory state with this panel of biomarkers may support physicians to identify a subset of patients more susceptible to the procedure failure and to develop cardiovascular adverse events after LER.

Regulation of cardiovascular health and disease by visceral adipose tissue-derived metabolic hormones

Visceral adipose tissue (VAT) is a metabolic organ known to regulate fat mass, and glucose and nutrient homeostasis. VAT is an active endocrine gland that synthesizes and secretes numerous bioactive mediators called 'adipocytokines/adipokines' into systemic circulation. These adipocytokines act on organs of metabolic importance like the liver and skeletal muscle. Multiple preclinical and in vitro studies showed strong evidence of the roles of adipocytokines in the regulation of metabolic disorders like diabetes, obesity and insulin resistance. Adipocytokines, such as adiponectin and omentin, are anti-inflammatory and have been shown to prevent atherogenesis by increasing nitric oxide (NO) production by the endothelium, suppressing endothelium-derived inflammation and decreasing foam cell formation. By inhibiting differentiation of vascular smooth muscle cells (VSMC) into osteoblasts, adiponectin and omentin prevent vascular calcification. On the other hand, adipocytokines like leptin and resistin induce inflammation and endothelial dysfunction that leads to vasoconstriction. By promoting VSMC migration and proliferation, extracellular matrix degradation and inflammatory polarization of macrophages, leptin and resistin increase the risk of atherosclerotic plaque vulnerability and rupture. Additionally, the plasma concentrations of these adipocytokines alter in ageing, rendering older humans vulnerable to cardiovascular disease. The disturbances in the normal physiological concentrations of these adipocytokines secreted by VAT under pathological conditions impede the normal functions of various organs and affect cardiovascular health. These adipokines could be used for both diagnostic and therapeutic purposes in cardiovascular disease.

Perivascular Adipose Tissue and Vascular Smooth Muscle Tone: Friends or Foes?

Perivascular adipose tissue (PVAT) is a specialized type of adipose tissue that surrounds most mammalian blood vessels. PVAT is a metabolically active, endocrine organ capable of regulating blood vessel tone, endothelium function, vascular smooth muscle cell growth and proliferation, and contributing critically to cardiovascular disease onset and progression. In the context of vascular tone regulation, under physiological conditions, PVAT exerts a potent anticontractile effect by releasing a plethora of vasoactive substances, including NO, H₂S, H₂O₂, prostacyclin, palmitic acid methyl ester, angiotensin 1-7, adiponectin, leptin, and omentin. However, under certain pathophysiological conditions, PVAT exerts pro-contractile effects by decreasing the production of anticontractile and increasing that of pro-contractile factors, including superoxide anion, angiotensin II, catecholamines, prostaglandins, chemerin, resistin, and visfatin. The present review discusses the regulatory effect of PVAT on vascular tone and the factors involved. In this scenario, dissecting the precise role of PVAT is a prerequisite to the development of PVAT-targeted therapies.

Prospects of potential adipokines as therapeutic agents in obesity-linked atherogenic dyslipidemia and insulin resistance

BACKGROUND

In normal circumstances, AT secretes anti-inflammatory adipokines (AAKs) which regulates lipid metabolism, insulin sensitivity, vascular hemostasis, and angiogenesis. However, during obesity AT dysfunction occurs and leads to microvascular imbalance and secretes several pro-inflammatory adipokines (PAKs), thereby favoring atherogenic dyslipidemia and insulin resistance. Literature suggests decreased levels of circulating AAKs and increased levels of PAKs in obesity-linked disorders. Importantly, AAKs have been reported to play a vital role in obesity-linked metabolic disorders mainly insulin resistance, type-2 diabetes mellitus and coronary heart diseases. Interestingly, AAKs counteract the microvascular imbalance in AT and exert cardioprotection via several signaling pathways such as PI3-AKT/PKB pathway. Although literature reviews have presented a number of investigations detailing specific pathways involved in obesity-linked disorders, literature concerning AT dysfunction and AAKs remains sketchy. In view of the above, in the present contribution an effort has been made to provide an insight on the AT dysfunction and role of AAKs in modulating the obesity and obesity-linked atherogenesis and insulin resistance.

MAIN BODY

"Obesity-linked insulin resistance", "obesity-linked cardiometabolic disease", "anti-inflammatory adipokines", "pro-inflammatory adipokines", "adipose tissue dysfunction" and "obesity-linked microvascular dysfunction" are the keywords used for searching article. Google scholar, Google, Pubmed and Scopus were used as search engines for the articles.

CONCLUSIONS

This review offers an overview on the pathophysiology of obesity, management of obesity-linked disorders, and areas in need of attention such as novel therapeutic adipokines and their possible future perspectives as therapeutic agents.

Correlation of serum omentin-1 level with clinical features and major adverse cardiac and cerebral events in patients undergoing continuous ambulatory peritoneal dialysis

Omentin-1 shows a critical protective role of cardiovascular events in chronic kidney disease. This study aimed to further assess serum omentin-1 level and its relationship with clinical features and accumulating major adverse cardiac/cerebral events (MACCE) risk in end-stage renal disease patients undergoing continuous ambulatory peritoneal dialysis (CAPD-ESRD). Totally, 290 CAPD-ESRD patients and 50 healthy controls (HCs) were recruited, and their serum omentin-1 levels were measured by enzyme-linked immunosorbent assay. All CAPD-ESRD patients were followed up for 36 months to assess accumulating MACCE rate. Omentin-1 level in CAPD-ESRD patients was lower than that in HCs [median (interquartile range): 229.350 (153.575-355.550) vs. 449.800 (354.125-527.450) pg/mL] (p < 0.001). Moreover, omentin-1 level was inversely related to C-reactive protein (CRP) (p = 0.028), total cholesterol (p = 0.023), and low-density lipoprotein cholesterol (p = 0.005), while there was no correlation in omentin-1 level with other clinical features in CAPD-ESRD patients. The accumulating MACCE rate was 4.5%, 13.1%, and 15.5% in the first, second, and third years respectively, and it was lower in CAPD-ESRD patients with high level of omentin-1 than those with low level of omentin-1 (p = 0.004). Furthermore, omentin-1 (hazard ratio (HR)=0.422, p = 0.013) and high-density lipoprotein cholesterol (HR = 0.396, p = 0.010) were independently associated with reduced accumulating MACCE rate; while age (HR = 3.034, p = 0.006), peritoneal dialysis duration (HR = 2.741, p = 0.006), CRP (HR = 2.289, p = 0.026), serum uric acid (HR = 2.538, p = 0.008) were independently related to higher accumulating MACCE rate in CAPD-ESRD patients. In conclusion, serum high omentin-1 level is associated with decreased inflammation, lipid levels, and accumulating MACCE risk in CAPD-ESRD patients.

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

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

Evaluation of Blood Levels of Omentin-1 and Orexin-A in Adults with Obstructive Sleep Apnea: A Systematic Review and Meta-Analysis

Background and objective: Obstructive sleep apnea (OSA) can be related to changes in the levels of adipokines and neuropeptides, which in turn may affect the energy balance components of neuronal cells. Herein, a systematic review and meta-analysis checked the changes in serum/plasma levels of omentin-1 (OM-1: an adipokine) and orexin-A (OXA: a neuropeptide) in adults (age > 18 years old) with OSA (aOSA) compared to controls. Materials and methods: Four databases (Cochrane Library, PubMed, Web of Science, and Scopus) were systematically searched until 14 November 2022, without any restrictions. The Joanna Briggs Institute (JBI) critical appraisal checklist adapted for case−control studies was used to assess the quality of the papers. The effect sizes were extracted using the Review Manager 5.3 software for the blood levels of OM-1 and OXA in aOSA compared with controls. Results: Thirteen articles, with six studies for OM-1 levels and eight for OXA levels, were included. The pooled standardized mean differences were −0.85 (95% confidence interval (CI): −2.19, 0.48; p = 0.21; I2 = 98%) and −0.20 (95%CI: −1.16, 0.76; p = 0.68; I2 = 96%) for OM-1 and OXA levels, respectively. Among the studies reporting OM-1, five were high and one was moderate quality. Among the studies reporting OXA, six were moderate, one was high, and one was low quality. Based on the trial sequential analysis, more participants are needed to confirm the pooled results of the analyses of blood levels of OM-1 and OXA. In addition, the radial plot showed outliers as significant factors for high heterogeneity. Conclusions: The main findings indicated a lack of association between the blood levels of OM-1 and OXA and OSA risk. Therefore, OM-1 and OXA did not appear to be suitable biomarkers for the diagnosis and development of OSA.

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

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

Lower circulating omentin-1 is independently linked to subclinical hypothyroidism reflecting cardiometabolic risk: an observational case-control and interventional, longitudinal study

BACKGROUND

Omentin-1, a newly discovered adipokine, is implicated in the modulation of the adipose phenotype, ameliorating systemic metabolism and exhibiting anti-atherogenic, anti-oxidative, cardioprotective, anti-inflammatory and insulin-sensitizing properties. Our goal was to explore circulating omentin-1 in subclinical hypothyroidism (SH) and determine its correlations with cardiometabolic risk factors.

METHODS

In a large case-control and interventional longitudinal study, serum omentin-1, metabolic and lipid parameters, inflammatory biomarkers, classic adipocytokines and cardiovascular risk factors were assessed in 120 consecutive patients with SH and 120 healthy controls matched on age, gender and date of blood draw. Sixteen patients with SH were administered L-T4 and, after six months, circulating omentin-1 and other biomarkers were determined.

RESULTS

SH subjects presented significantly decreased circulating omentin-1 than control individuals (P<0.001). In all study participants, omentin-1 was negatively correlated with TSH, anti-thyroid antibodies, HOMA-IR, C-peptide, lipid and inflammatory biomarkers, adipokines and cardiovascular risk factors, including Framingham score and apolipoprotein B. Omentin-1 was positively associated with adiponectin and HDL-C. Circulating omentin-1 was independently associated with SH occurrence, above and beyond clinical and cardiometabolic factors (P=0.04). TSH was a negative independent predictor of serum omentin-1 levels (P<0.001). L-T4 treatment did not alter considerably the lower omentin-1 levels in treated SH patients (P=0.07).

CONCLUSIONS

Omentin-1 may be a useful non-invasive biomarker reflecting cardiometabolic risk as well as a promising therapeutic target. More mechanistic and larger prospective studies shedding light on the pathogenetic role of omentin-1 in SH are required to confirm these findings.

Therapeutic Effects of Omentin-1 on Pulmonary Fibrosis by Attenuating Fibroblast Activation via AMP-Activated Protein Kinase Pathway

Idiopathic pulmonary fibrosis (IPF) is a fatal age-related chronic lung disease, characterized by progressive scarring of the lungs by activated fibroblasts. The effect of omentin-1 against pulmonary fibrosis and fibroblast activation has not been investigated. The purpose of this experiment is to investigate the role of omentin-1 in bleomycin (BLM)-induced lung fibrosis and its mechanism. Our results showed that the loss of omentin-1 exaggerated lung fibrosis induced by BLM. On the contrary, adenoviral-overexpression of omentin-1 significantly alleviated BLM-induced lung fibrosis both in preventive and therapeutic regimens. Moreover, omentin-1 prevented fibroblast activation determined by a decreased number of S100A4+ (fibroblasts marker) α-SMA+ cells in vivo, and a decreased level of α-SMA expression both in mice primary fibroblasts and human primary fibroblasts induced by TGF-β in vitro. Furthermore, the phosphorylation of AMP-activated protein kinase (p-AMPK) was significantly lower in the fibrotic foci induced by BLM, and the adenoviral-overexpression of omentin-1 significantly increased the p-AMPK level in vivo. Importantly, Compound C, the inhibitor of AMPK, significantly attenuated the protective effect of omentin-1 on BLM-induced lung fibrosis and reversed the effect of omentin-1 on fibroblast activation by TGF-β. Omentin-1 can be a promising therapeutic agent for the prevention and treatment of lung fibrosis.

Epicardial Adipose Tissue as an Independent Cardiometabolic Risk Factor for Coronary Artery Disease

During the last decades, visceral adiposity has been at the forefront of scientific research because of its complex role in the pathogenesis of cardiovascular diseases. Epicardial adipose tissue (EAT) is the visceral lipid compartment between the myocardium and the visceral pericardium. Due to their unobstructed anatomic vicinity, epicardial fat and myocardium are nourished by the same microcirculation. It is widely known that EAT serves as an energy lipid source and thermoregulator for the human heart. In addition to this, epicardial fat exerts highly protective effects since it releases a great variety of anti-inflammatory molecules to the adjacent cardiac muscle. Taking into account the unique properties of human EAT, it is undoubtedly a key factor in cardiac physiology since it facilitates complex heart functions. Under pathological circumstances, however, epicardial fat promotes coronary atherosclerosis in a variety of ways. Therefore, the accurate estimation of epicardial fat thickness and volume could be utilized as an early detecting method and future medication target for coronary artery disease (CAD) elimination. Throughout the years, several therapeutic approaches for dysfunctional human EAT have been proposed. A balanced healthy diet, aerobic and anaerobic physical activity, bariatric surgery, and pharmacological treatment with either traditional or novel antidiabetic and antilipidemic drugs are some of the established medical approaches. In the present article, we review the current knowledge regarding the anatomic and physiological characteristics of epicardial fat. In addition to this, we describe the pathogenic mechanisms which refer to the crosstalk between epicardial fat alteration and coronary arterial atherosclerosis development. Lastly, we present both lifestyle and pharmacological methods as possible treatment options for EAT dysfunction.

Adipokines, adiposity, and atherosclerosis

Characterized by a surplus of whole-body adiposity, obesity is strongly associated with the prognosis of atherosclerosis, a hallmark of coronary artery disease (CAD) and the major contributor to cardiovascular disease (CVD) mortality. Adipose tissue serves a primary role as a lipid-storage organ, secreting cytokines known as adipokines that affect whole-body metabolism, inflammation, and endocrine functions. Emerging evidence suggests that adipokines can play important roles in atherosclerosis development, progression, as well as regression. Here, we review the versatile functions of various adipokines in atherosclerosis and divide these respective functions into three major groups: protective, deteriorative, and undefined. The protective adipokines represented here are adiponectin, fibroblast growth factor 21 (FGF-21), C1q tumor necrosis factor-related protein 9 (CTRP9), and progranulin, while the deteriorative adipokines listed include leptin, chemerin, resistin, Interleukin- 6 (IL-6), and more, with additional adipokines that have unclear roles denoted as undefined adipokines. Comprehensively categorizing adipokines in the context of atherosclerosis can help elucidate the various pathways involved and potentially pave novel therapeutic approaches to treat CVDs.

Exercise training modulates adipokine dysregulations in metabolic syndrome

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

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

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

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

The Role of Anti-Inflammatory Adipokines in Cardiometabolic Disorders: Moving beyond Adiponectin

The global burden of obesity has multiplied owing to its rapidly growing prevalence and obesity-related morbidity and mortality. In addition to the classic role of depositing extra energy, adipose tissue actively interferes with the metabolic balance by means of secreting bioactive compounds called adipokines. While most adipokines give rise to inflammatory conditions, the others with anti-inflammatory properties have been the novel focus of attention for the amelioration of cardiometabolic complications. This review compiles the current evidence on the roles of anti-inflammatory adipokines, namely, adiponectin, vaspin, the C1q/TNF-related protein (CTRP) family, secreted frizzled-related protein 5 (SFRP5), and omentin-1 on cardiometabolic health. Further investigations on the mechanism of action and prospective human trials may pave the way to their clinical application as innovative biomarkers and therapeutic targets for cardiovascular and metabolic disorders.

Omentin-1 Modulates Macrophage Function via Integrin Receptors αvβ3 and αvβ5 and Reverses Plaque Vulnerability in Animal Models of Atherosclerosis

Backgrounds: Omentin-1 is a novel cytokine that is primarily released by the epicardial adipose tissue. Molecular structure analysis revealed that it contained a fibrinogen-like domain. Clinical studies have demonstrated that the expression of omentin-1 is tightly associated with the development of cardiovascular diseases, but the receptor by which omentin-1 modulates macrophage function has not been identified yet. Objective: This study sought to investigate the effect of omentin-1 on already-established atherosclerosis (AS) lesions in both ApoE-/- and Ldlr^-/- mice and further, study its underlying mechanisms. Methods and Results: We investigated the effect of omentin-1 on the plaque phenotype by implanting a minipump in ApoE-/- and Ldlr^-/- mice. In vivo studies showed that the infusion of omentin-1 increased the collagen content and mitigated the formation of the necrotic core in both animal models. Immunohistochemistry and immunofluorescence analysis revealed that omentin-1 suppressed inflammatory cytokines expression, macrophage infiltration, and apoptosis within the plaque. An immunoprecipitation experiment and confocal microscopy analysis confirmed the binding of omentin-1 to the integrin receptors αvβ3 and αvβ5. The cell studies demonstrated that omentin-1 suppressed the apoptosis and inflammatory cytokines expression induced by the oxidized low-density lipoprotein in the macrophage. In addition, omentin-1 promoted the phosphorylation of the integrin-relevant signaling pathway as well as the Akt and AMPK in the macrophage. The addition of the inhibitor of the integrin receptor or interfering with the expression of the integrin subunit αv (ITGAV) both significantly abrogated the bioeffects induced by omentin-1. A flow cytometry analysis indicated that the antibodies against αvβ3 and αvβ5 had a competitive effect on the omentin-1 binding to the cell membrane. Conclusions: The administration of adipokine omentin-1 can inhibit the necrotic cores formation and pro-inflammatory cytokines expression within the AS lesion. The mechanisms may include the suppression of apoptosis and pro-inflammatory cytokines expression in the macrophage by binding to the integrin receptors αvβ3 and αvβ5.

Circulating Omentin-1 as a Biomarker at the Intersection of Postmenopausal Breast Cancer Occurrence and Cardiometabolic Risk: An Observational Cross-Sectional Study

Aberrant circulating omentin-1, which is an anti-inflammatory and pro-apoptotic adipokine, has been reported in various solid tumors. Therefore, we investigated whether or not circulating omentin-1 could be associated with postmenopausal BC (PBC) and could be used as a potential diagnostic and clinical tool taking into consideration clinicopathologic features, tumor markers, as well as anthropometric, metabolic, and inflammatory parameters. Serum omentin-1, tumor markers (CA15-3 and CEA); metabolic (insulin, glucose, HOMA index, and serum lipids), anthropometric (BMI, waist circumference, and fat mass), and inflammatory (TNF-α, IL-6, hsCRP) parameters; classic adipokines (leptin and adiponectin); the Mediterranean diet (MedDiet) score; and cardiovascular (CVD) risk were determined in 103 postmenopausal women with pathologically confirmed incident invasive BC, 103 controls matched on age, 51 patients with benign breast lesions (BBL), and 50 obese postmenopausal women of similar age. The mean serum omentin-1 was significantly lower in cases than in controls and patients with BBL (p < 0.001). In the patients, omentin-1 was inversely associated with tumor, metabolic and inflammatory biomarkers, cancer stage, and the number of infiltrated lymph nodes (p < 0.05). In all study participants, omentin-1 was negatively correlated with CVD risk and positively correlated with MedDiet score. Lower circulating omentin-1 was independently associated with PBC occurrence above and beyond known risk factors. According to the ROC curve analysis, the overall diagnostic performance of omentin-1 (0.84, 95% CI 0.79-0.89) is similar to CA15-3. Circulating omentin-1 may be a biomarker at the intersection of PBC and cardiometabolic risk in postmenopausal women, and could be modulated by the adoption of a MedDiet. Further mechanistic and large multicentric prospective and longitudinal studies are required to elucidate the ontological role of omentin-1 in BC and CVD risks, as well as its diagnostic and prognostic ability and its therapeutic potential.

Association of increased levels of omentin-1 and carotid intima-media thickness with early signs of cardiovascular risk in patients with polycystic ovary syndrome: A prospective case control study

AIM

Omentin-1, an adipokine primarily secreted from visceral adipose tissue, regulates metabolic homeostasis, whereas carotid intima-media thickness (CIMT) is a valid marker for early diagnosis of atherosclerosis. We aimed to investigate whether polycystic ovary syndrome (PCOS) is related to levels of omentin-1 and CIMT and demonstrate the association with cardiovascular risk.

METHODS

A prospective case-control study was performed on 47 PCOS patients and 35 healthy subjects. Hormonal and metabolic parameters, levels of serum omentin-1, and CIMT were evaluated in the two groups.

RESULTS

The right, left, total CIMT, and levels of serum omentin-1 were significantly higher in the PCOS group than in the healthy controls (p = 0.015, p = 0.009, p = 0.021, and p = 0.002, respectively). Using multiple linear and backward elimination regression analyses, serum omentin-1 was found to be independently associated with age and Ln-transformed homeostasis model assessment of insulin resistance, and cardiovascular parameters were independently associated with body mass index (BMI). In the PCOS group, the means of right, left, and total CIMT were significantly higher in the subgroup with BMI levels ≥25 kg/m² compared to the subgroup with BMI levels <25 kg/m² (p < 0.001 for all comparisons).

CONCLUSION

A significant increase in CIMT is associated with cardiovascular risk in patients with PCOS. Levels of serum omentin-1 were found to be significantly higher in early PCOS cases at a younger age, acting as a protective acute-phase reactant.

Association Between Coronary Artery Disease and Plasma Omentin-1 Levels

Introduction: Omentin-1 is secreted from visceral adipose tissue that contributes to chronic inflammatory diseases’ pathogenesis, including cardiovascular events. In this case-control study, we will determine the association between plasma omentin and coronary artery disease (CAD).

Methods: This is a case-control study, conducted from June 2020 to April 2021 in the cardiology unit of a tertiary care hospital in Pakistan. Patients diagnosed with CAD (n = 300) within the last six months were included in the study. Another 300 participants without CAD and with similar demographic profiles were included in the control group. A blood sample of 5 ml was drawn from participants of both groups and sent to the laboratory to test for plasma omentin level.

Results: Plasma omentin level was significantly lower in patients with CAD compared to the patients without CAD (61.21 ± 10.21 ng/dL vs. 95.22 ± 12.21 ug/L; p-value: <0.0001). In both genders, the plasma omentin-1 was lower in patients with CAD compared to patients without CAD (p-value: <0.0001).

Conclusion: The present study revealed a negative association between omentin-1 and CAD. We speculate that low levels of omentin-1 might play a role in the pathogenesis of atherosclerosis. Therefore, plasma omentin-1 can be a potential biomarker to predict the development and progression of CAD.

Adipokines and Chronic Rheumatic Diseases: from Inflammation to Bone Involvement

Besides its well-known role as energy storage tissue, adipose tissue is a biologically active tissue that can also be considered as an endocrine organ, as it is able to secrete adipokines. These bioactive factors, similar in structure to cytokines, are involved in several physiological and pathological conditions, such as glucose homeostasis, angiogenesis, blood pressure regulation, control of food intake, and also inflammation and bone homeostasis via endocrine, paracrine, and autocrine mechanisms. Given their pleiotropic functions, the role of adipokines has been evaluated in chronic rheumatic osteoarticular inflammatory diseases, particularly focusing on their effects on inflammatory and immune response and on bone alterations. Indeed, these diseases are characterized by different bone complications, such as local and systemic bone loss and new bone formation. The aim of this review is to summarize the role of adipokines in rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, osteoarthritis, and osteoporosis, especially considering their role in the pathogenesis of bone complications typical of these conditions.

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

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

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.

Metabolic regulation of immune cells in proinflammatory microenvironments and diseases during ageing

The process of ageing includes molecular changes within cells and interactions between cells, eventually resulting in age-related diseases. Although various cells (immune cells, parenchymal cells, fibroblasts and endothelial cells) in tissues secrete proinflammatory signals in age-related diseases, immune cells are the major contributors to inflammation. Many studies have emphasized the role of metabolic dysregulation in parenchymal cells in age-related inflammatory diseases. However, few studies have discussed metabolic modifications in immune cells during ageing. In this review, we introduce the metabolic dysregulation of major nutrients (glucose, lipids, and amino acids) within immune cells during ageing, which leads to dysfunctional NAD + metabolism that increases immune cell senescence and leads to the acquisition of the corresponding senescence-associated secretory phenotype (SASP). We then focus on senescent immune cell interactions with parenchymal cells and the extracellular matrix and their involvement in angiogenesis, which lead to proinflammatory microenvironments in tissues and inflammatory diseases at the systemic level. Elucidating the roles of metabolic modifications in immune cells during ageing will provide new insights into the mechanisms of ageing and therapeutic directions for age-related inflammatory diseases.

Cell senescence: basic mechanisms and the need for computational networks in vascular ageing

This review seeks to provide an update of the mechanisms of vascular cell senescence, from newly identified molecules to arterial ageing phenotypes, and finally to present a computational approach to connect these selected proteins in biological networks. We will discuss current key signalling and gene expression pathways by which these focus proteins and networks drive normal and accelerated vascular ageing. We also review the possibility that senolytic drugs, designed to restore normal cell differentiation and function, could effectively treat multiple age-related vascular diseases. Finally, we discuss how cell senescence is both a cause and a consequence of vascular ageing because of the possible feedback controls between identified networks.

Emerging Role of Adipocyte Dysfunction in Inducing Heart Failure Among Obese Patients With Prediabetes and Known Diabetes Mellitus

Adipose tissue dysfunction is a predictor for cardiovascular (CV) events and heart failure (HF) in patient population with obesity, metabolic syndrome, and known type 2 diabetes mellitus. Previous preclinical and clinical studies have yielded controversial findings regarding the role of accumulation of adipose tissue various types in CV risk and HF-related clinical outcomes in obese patients. There is evidence for direct impact of infiltration of epicardial adipocytes into the underlying myocardium to induce adverse cardiac remodeling and mediate HF development and atrial fibrillation. Additionally, perivascular adipocytes accumulation is responsible for release of proinflammatory adipocytokines (adiponectin, leptin, resistin), stimulation of oxidative stress, macrophage phenotype switching, and worsening vascular reparation, which all lead to microvascular inflammation, endothelial dysfunction, atherosclerosis acceleration, and finally to increase in CV mortality. However, systemic effects of white and brown adipose tissue can be different, and adipogenesis including browning of adipose tissue and deficiency of anti-inflammatory adipocytokines (visfatin, omentin, zinc-α2-glycoprotein, glypican-4) was frequently associated with adipose triglyceride lipase augmentation, altered glucose homeostasis, resistance to insulin of skeletal muscles, increased cardiomyocyte apoptosis, lowered survival, and weak function of progenitor endothelial cells, which could significantly influence on HF development, as well as end-organ fibrosis and multiple comorbidities. The exact underlying mechanisms for these effects are not fully understood, while they are essential to help develop improved treatment strategies. The aim of the review is to summarize the evidence showing that adipocyte dysfunction may induce the onset of HF and support advance of HF through different biological mechanisms involving inflammation, pericardial, and perivascular adipose tissue accumulation, adverse and electrical cardiac remodeling, and skeletal muscle dysfunction. The unbalancing effects of natriuretic peptides, neprilysin, and components of renin–angiotensin system, as exacerbating cause of altered adipocytokine signaling on myocardium and vasculature, in obesity patients at high risk of HF are disputed. The profile of proinflammatory and anti-inflammatory adipocytokines as promising biomarker for HF risk stratification is discussed in the review.

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.

The role of adipokines in the modulation of lymphoid lineage cell development and activity: An overview

Adipokines are predominantly known to play a vital role in the control of food intake, energy homeostasis and regulation of glucose and lipid metabolism. However, evidence supporting the concept of their extensive involvement in immune system defence mechanisms and inflammatory processes continues to grow. Some of the adipokines, that is, leptin and resistin, have been recognized to exhibit mainly pro-inflammatory properties, whereas others such as visfatin, chemerin, apelin and vaspin have been found to exert regulatory effects. In contrast, adiponectin or omentin are known for their anti-inflammatory activities. Hence, adipokines influence the activity of various cells engaged in innate immune response and inflammatory processes mainly by affecting adhesion molecule expression, chemotaxis, apoptosis and phagocytosis, as well as mediators production and release. However, much less is known about the role of adipokines in processes involving lymphoid lineage cells. This review summarizes the current knowledge regarding the importance of different adipokines in the lymphopoiesis, recirculation, differentiation and polarization of lymphoid lineage cells. It also provides insight into the influence of selected adipokines on the activity of those cells in tissues.

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.

Newly Discovered Adipokines: Pathophysiological Link Between Obesity and Cardiometabolic Disorders

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

Is there a relationship between serum omentin level and acute phase response in patients with familial Mediterranean fever?

OBJECTIVES

Familial Mediterranean fever (FMF) is an autoinflammatory disease characterized by frequent attacks and chronic inflammation. Subclinical inflammation continues during the attack-free period. Omentin is an anti-inflammatory adipokine, which plays important roles in the adjustments of glucose metabolism, cardiovascular homeostasis and atherosclerosis. The aim is to investigate the omentin levels in FMF patients and to assess the association with markers of subclinical inflammation in FMF patients such as serum amyloid A (SAA), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP).

METHOD

This cross-sectional study included 54 consecutive adult FMF patients (27 male, 27 female) and 28 healthy individuals (16 male, 12 female). The FMF patients were separated into 3 groups: (1) attack-free group, (2) active-attack group and (3) colchicine-resistant group. Serum omentin levels were compared between the FMF patients and the healthy control group.

RESULTS

A significant difference was determined between the FMF patients and healthy control subjects in terms of omentin levels (108.05 (19.97-343.22) vs. 199.5 (42.98-339.41) p < 0.05). SAA values were significantly higher in the FMF patients compared with the healthy control group. When the FMF patients were examined as separate groups, serum omentin values were lower in the colchicine-resistant group than in the groups without resistance (76.64 (19.77-224.33) vs. 186.47 (28.41-343.21) p = 0.006).

CONCLUSIONS

FMF patients with colchicine resistance are associated with decreased omentin concentrations, probably mediated by inflammation-driven mechanisms. Key Points • Omentin is a type of adipokine which has an anti-inflammatory effect by inhibiting the inflammatory cytokine network. • Decreased omentin levels are associated with increased obesity, insulin resistance and comorbidities. • We report that omentin levels fluctuate in various diseases. In addition, we have focused on the levels of omentin in patients with FMF, as it may act as a biomarker for colchicine resistance.

Association of selected adipokines with metabolic syndrome and cardio-metabolic risk factors in young males

The study aimed to investigate association of circulating leptin, adiponectin, chemerin, and omentin-1 with metabolic syndrome (MetS) and cardio-metabolic risk factors in youths. Thirty eight young males were enrolled. Participants underwent anthropometric and blood pressure measures, and fasting blood sampling. Plasma leptin, adiponectin, chemerin, omentin-1 and insulin were measured by ELISA methods. Multiple linear regression models, adjusting for age, MetS traits, C-reactive protein (CRP) and homeostasis model assessment of insulin resistance (HOMA-IR), were applied to determine correlates for each adipokine. Eleven participants meet criteria of MetS. These individuals had higher leptin and chemerin and lower adiponectin plasma concentrations than those without MetS. Plasma leptin and chemerin were positively related, and adiponectin and omentin-1 were inversely related to cardio-metabolic traits. In multivariate models, predictors of leptin were age (β, 0.20, P = 0.01), abdominal obesity (β, 0.24, P = 0.06), raised blood pressure (β, 0.40, P = 0.01), raised triglycerides (β, 0.19, P = 0.01) and CRP (β, 0.31, P = 0.01). Chemerin was associated with abdominal obesity (β, 0.33, P = 0.09) and CRP (β, 0.29, P = 0.04), and adiponectin was associated with raised triglycerides (β, -0.26, P = 0.05), decreased HDL-C (β, -0.28, P = 0.06) and CRP (β, -0.48, P = 0.01). HOMA-IR (β, -0.39, P = 0.09) was the only predictor for omentin. MetS is associated with an altered plasma adipokines profile, with increased leptin and chemerin and decreased adiponectin circulating levels. These findings suggest a beneficial potential of adiponectin and omentin, but a detrimental potential of leptin and chemerin. Further research is needed to lighten the role of adipose tissue-derived adipokines in cardio-metabolic health.

Pregnancy-induced Cardiovascular Pathologies: Importance of Structural Components and Lipids

Pregnancy leads to adaptations for maternal and fetal energy needs. The cardiovascular system bears the brunt of the adaptations as the heart and vessels enable nutrient supply to maternal organs facilitated by the placenta to the fetus. The components of the cardiovascular system are critical in the balance between maternal homeostatic and fetus driven homeorhetic regulation. Since lipids intersect maternal cardiovascular function and fetal needs with growth and in stress, factors affecting lipid deposition and mobilization impact risk outcomes. Here, the cardiovascular components and functional derangements associated with cardiovascular pathology in pregnancy, vis-à-vis lipid deposition, mobilization and maternal and/or cardiac and fetal energy needs are detailed. Most reports on the components and associated pathology in pregnancy, are on derangements affecting the extracellular matrix and epicardial fat, followed by the endothelium, vascular smooth muscle, pericytes and myocytes. Targeted studies on all cardiovascular components and pathological outcomes in pregnancy will enhance targeted interventions.

Omentin-1 is associated with atrial fibrillation in patients with cardiac valve disease

BACKGROUND

Epicardial adipose tissue (EAT) remodeling and adipocytokines are associated with structural remodeling in atrial fibrillation (AF). However, the role of omentin-1, a novel adipocytokine, in structural remodeling remains unknown.

METHODS

Hematoxylin and eosin (H&E) and Masson's trichrome stains were used to investigate the histology of EAT and right atrial appendages. The expression levels of adipocytokines in these human samples were determined by immunohistochemical assay and western blotting. Models of transforming growth factor (TGF)-β1-induced activation of cardiac fibroblasts (CFs) and TGF-β1-induced endothelial-mesenchymal transition (EndMT) of human umbilical vein endothelial cell (HUVEC) were established to explore roles of omentin-1 in these processes. To determine changes in adipocytokines secretion under hypoxia conditions, adipocytes were treated with 5% O₂ and 95% N₂, and then CFs and HUVECs were co-cultured with the conditioned medium of adipocytes to determine the effects of hypoxia-treated adipocytes on these cells.

RESULTS

Expression of omentin-1 was downregulated in the EAT and right atrial appendages from patients with AF compared to samples from patients without AF, while the TGF-β1 level was upregulated in EAT from patients with AF. EAT from patients with AF exhibited adipocyte hypertrophy and severe interstitial fibrosis. Omentin-1 inhibited TGF-β1-induced CF activation and reversed TGF-β1-induced HUVEC EndMT. Adipocytes treated with hypoxia exhibited downregulation of omentin-1 and partly activated CFs.

CONCLUSIONS

This study demonstrated that omentin-1 was an antifibrotic adipocytokine and was downregulated in patients with AF, which was partly mediated by hypoxia.

Biomarkers of vascular disease in diabetes: the adipose-immune system cross talk

Experimental and clinical studies aimed at investigating the mechanism(s) underlying vascular complications of diabetes indicate that a great number of molecules are involved in the pathogenesis of these complications. Most of these molecules are inflammatory mediators or markers generated by immune or adipose tissue. Some of them, i.e. resistin and sortilin, have been shown to be involved in the cross talk between adipocytes and inflammatory cells. This interaction is an attractive area of research, particularly in type 2 diabetes and obesity. Other proteins, such as adiponectin and visfatin, appear to be more promising as possible vascular markers. In addition, some molecules involved in calcium/phosphorus metabolism, such as klotho and FGF23, have an involvement in the pathogenesis of diabetic vasculopathy, which appears to be dependent on the degree of vascular impairment. Inflammatory markers are a promising tool for treatment decisions while measuring plasma levels of adipokines, sortilin, Klotho and FGF23 in adequately sized longitudinal studies is expected to allow a more precise characterization of diabetic vascular disease and the optimal use of personalized treatment strategies.

Omentin-1 Ameliorated Free Fatty Acid-Induced Impairment in Proliferation, Migration, and Inflammatory States of HUVECs

Objectives

Endothelial cell injury is a critical pathological change during the development of atherosclerosis. Here, we explored the effect of omentin-1 on free fatty acid- (FFA-) induced endothelial cell injury.

Methods

An FFA-induced endothelial cell injury model was established to investigate the role of omentin-1 in this process. Cell proliferation was analyzed with the Cell Counting Kit assay and flow cytometry. Scratch and transwell assays were used to evaluate cell migration. Factors secreted by endothelial cells after injury were detected by western blotting, reverse-transcription quantitative polymerase chain reaction, and cellular fluorescence assay.

Results

Omentin-1 rescued the FFA-induced impaired proliferation and migration capabilities of human umbilical vein endothelial cells (HUVECs). It decreased the number of THP-1 cells attached to HUVECs in response to injury and inhibited the FFA-induced proinflammatory state of HUVECs.

Conclusion

Omentin-1 could partly ameliorate FFA-induced endothelial cell injury.