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

Associations of circulating omentin-1 levels and long noncoding RNA MALAT1 expression with coronary heart disease in patients with type 2 diabetes mellitus

Coronary heart disease (CHD) is a severe diabetic vascular complication and the main cause of mortality among diabetes patients. Early diagnosis of CHD could prevent its development. Both omentin-1 (Oment-1) and the long noncoding RNA MALAT1 (lncRNA MALAT1) can be detected in peripheral blood and exhibit protective or detrimental effects on CHD. However, whether these two factors could be predictive of CHD in T2DM patients remains unclear. Therefore, this study aimed to investigate the associations of circulating Oment-1 levels and the expression of MALAT1 with CHD in T2DM patients and to assess their predictive efficacy. A total of 137 T2DM patients were enrolled, including 68 patients without CHD (T2DM group) and 69 patients with CHD (T2DM + CHD group). Clinical parameters were collected, and plasma Oment-1 was measured by enzyme-linked immunosorbent assay (ELISA). RNA was isolated from peripheral monocytes, and the expression of MALAT1 was determined by quantitative PCR. Cardiac function was measured by echocardiography. Compared with that in T2DM patients, the plasma Oment-1 level was significantly lower, while the expression of MALAT1 was significantly greater in T2DM + CHD patients (all P values < 0.01). Bivariate correlation analysis indicated that Oment-1 was positively correlated with the left ventricular ejection fraction (LVEF) (P < 0.01). MALAT1 expression was negatively correlated with LVEF but positively correlated with age and DM duration (P < 0.05). Binary logistic regression suggested that Oment-1 and MALAT1 were significantly associated with the presence of CHD. Receiver operating characteristic (ROC) curve analysis demonstrated that both Oment-1 (AUC = 0.663, sensitivity = 75%, specificity = 49%) and MALAT1 (AUC = 0.749, sensitivity = 73%, specificity = 66%) had significant diagnostic value for CHD among T2DM patients. Notably, the combination of Oment-1 and MALAT1 exhibited better diagnostic efficiency (AUC = 0.771, sensitivity = 66.7%, specificity = 75.3%). In conclusion, decreased circulating Oment-1 levels and increased MALAT1 expression are closely associated with CHD in T2DM patients, and their combination offers superior diagnostic efficiency, suggesting Oment-1 and MALAT1 may serve as a non-invasive tool for the early CHD detection and risk stratification in high-risk T2DM patients. Further studies are warranted to explore the pathophysiological mechanisms of Omentin-1 and MALAT1 in the pathogenesis of CHD in T2DM and to validate their clinical utility as potential biomarkers in large cohort studies.

Targeting of AMPK/MTOR signaling in the management of atherosclerosis: Outmost leveraging

Atherosclerosis (AS) is a chronic vascular disorder that is characterized by the thickening and narrowing of arteries due to the development of atherosclerotic plaques. The traditional risk factors involved in AS are obesity, type 2 diabetes (T2D), dyslipidemia, hypertension, and smoking. Furthermore, non-traditional risk factors for AS, such as inflammation, sleep disturbances, physical inactivity, air pollution, and alterations of gut microbiota, gained attention in relation to the pathogenesis of AS. Interestingly, the pathogenesis of AS, is complex and related to different abnormalities of cellular and sub-cellular signaling pathways. It has been illustrated that AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (MTOR) pathways are involved in AS pathogenesis. Mounting evidence indicated that AMPK plays a critical role in attenuating the development of AS by activating autophagy, which is impaired during atherogenesis. AMPK has a vasculoprotective effect by reducing lipid accumulation, inflammatory cell proliferation, and the release of pro-inflammatory cytokines, as well as decreasing inflammatory cell adhesion to the vascular endothelium. AMPK activation by metformin inhibits the migration of vascular smooth muscle cells (VSMCs) and AS development. However, the MTOR pathway contributes to AS by inhibiting autophagy, highlighting autophagy as a crucial link between the AMPK and MTOR pathways in AS pathogenesis. The MTOR is a key inducer of endothelial dysfunction and is involved in the development of AS. Therefore, both the AMPK and MTOR pathways play a crucial role in the pathogenesis of AS. However, the exact role of AMPK and MTOR pathways in the pathogenesis of AS is not fully clarified. Therefore, this review aims to discuss the potential role of the AMPK/MTOR signaling pathway in AS, and how AMPK activators and MTOR inhibitors influence the development and progression of AS. In conclusion, AMPK activators and MTOR inhibitors have vasculoprotective effects against the development and progression of AS.

Intelectin-1 promotes granulosa cells proliferation and modulates apoptosis via ERK1/2, AKT, and insulin receptor signaling pathways in Large White and Meishan pigs

Maintaining the proper balance between granulosa cells (Gc) proliferation and apoptosis is crucial for folliculogenesis and female fertility. Our previous study showed expression of omentin-1 (intelectin-1, ITLN1) in the porcine ovarian follicles; however, its impact on Gc functions remains unknown. Therefore, this study aimed to determine the in vitro effects of ITLN1 on Gc proliferation and apoptosis in Large White (LW) and Meishan (MS) pigs. These breeds were chosen due to their distinct reproductive characteristics: MS pigs are known for maintaining a higher number of follicles during the follicular phase and exhibiting greater estradiol synthesis compared to LW pigs. Porcine Gc were incubated with ITLN1 (10-100 ng/mL) for 24-72 h, and the viability/proliferation (alamarBlue/BrdU assays), cell cycle progression (flow cytometry) and the gene and protein expression of proliferation/apoptotic markers (PCNA, cyclins A1, B2, D1, E1, caspases-3, -9, BCL-2, BAX, FAS, FADD, XIAP) (real-time PCR, western blotting) were assessed. Next, the effect of ITLN1 on the phosphorylation of several kinases (AKT, AMPK, ERK1/2, STAT3, PKA) and the gene and protein expression of the insulin receptor (INSR) were studied (real-time PCR, western blotting). Then, using pharmacological inhibitors of ERK1/2 (PD98059, 5 μM), AKT (LY294002, 10 μM) and INSR (1 μM), treated alone or with ITLN1 (S961, 50 ng/mL), we analyzed its involvement in the effects of ITLN1 on Gc proliferation/apoptosis. We demonstrated that ITLN1 had a mitogenic effect on Gc by enhancing cell cycle progression and modulating the levels of PCNA, cyclins and apoptotic factors via ERK1/2, AKT, and INSR, suggesting that ITLN1 is a newly identified regulator in ovarian folliculogenesis, regardless of the fatness degree of pigs.

ANGPTL3 accelerates atherosclerotic progression via direct regulation of M1 macrophage activation in plaque

INTRODUCTION

The N-terminal domain of angiopoietin-like protein 3 (ANGPTL3) inhibits lipoprotein lipase activity. Its C-terminal fibrinogen-like (FBN) domain is a ligand of macrophage integrin αvβ3.

OBJECTIVES

ANGPTL3 might home to plaque where it directly regulates macrophage function via integrin αvβ3 for atherosclerosis progression.

METHODS

Ldlr-/- mice on a high-fat diet and ApoE-/- mice on a chow diet were received adeno-associated virus (AAV)-mediated Angptl3 gene transfer and followed up for 12 weeks. ApoE-/- mice were injected AAV containing FLAG-tagged Angptl3 cDNA for tracing. Atherosclerotic features were compared between Angptl3-/-ApoE-/- mice and ApoE-/- littermates. THP-1 cells were exposed to 0 or 50 μg/ml ANGPTL3 FBN domain for 24 h to evaluate Toll-like receptor (TLR)4 expression using western blot analysis and circulating cytokine and chemokine profiles by the MILLIPLEX MAP assay. Phospho-proteomic profile was established in ANGPTL3-treated macrophages. Integrin β3 deficient THP-1 cells were obtained by sgRNAs targeting RGD sequence using Lentivirus-Cas9 system.

RESULTS

Angptl3 overexpression increased atherosclerotic progression and CD68+ macrophages in plaque (p < 0.05 for all). By immunostaining, FLAG+ cells were identified in plaque of gene transferred ApoE-/- mice. Fluorescent immunostaining detected co-localisation of Angptl3 and CD68 in plaque macrophages. Phospho-proteomic analysis revealed that Angptl3 induced phosphorylation of proteins that were involved in the IL-17 signalling pathway in THP-1 cells. In vitro, ANGPTL3 treatment increased the production of interleukin (IL)-1β and tumour necrosis factor-α in THP-1 cells (p < 0.05 for both). Exposure of ANGPTL3 to THP-1 cells induced Akt phosphorylation which was weakened in integrin β3 deficient ones. ANGPTL3 elevated TLR4 expression via Akt phosphorylation. In response to lipopolysaccharide, nuclear factor-κB activity was 2.2-fold higher in THP-1 cells pre-treated with ANGPTL3 than in untreated cells (p < 0.05).

CONCLUSIONS

Targeting ANGPTL3 could yield a dual benefit of lowering lipid levels in the blood and suppressing macrophage activation in plaque.

Mouse model of post-traumatic stress disorder negatively impacts cardiac homeostasis

Post-traumatic stress disorder (PTSD) is a disabling psychological disorder characterized by chronic symptoms of intrusiveness, avoidance, and hyperarousal after a traumatic event. Retrospective studies have indicated PTSD increases the risk for cardiovascular disease (CVD) including arrhythmia, hypertension, and myocardial infarction. The goal of this study was to: 1) use a murine model of cued fear conditioning (inescapable foot shock, IFS) to develop a scoring method to distinguish a PTSD-like phenotype, and 2) use this model system to characterize the cardiac phenotype and function in mice with extreme PTSD-like behaviors. We compared 3 groups, controls, non-responders (NR), and PTSD-like mice at 2 time points [4-weeks and 8-weeks post-IFS] to compare left ventricular structure and function. Assessment of cardiac function showed both male and female PTSD-like mice had increased isovolumetric relaxation time at 8-weeks post-IFS, whereas only females demonstrated increases in E/e', left atrial diameter, and decreased ejection fraction compared to control mice. Female PTSD-like mice also demonstrated increased interstitial fibrosis through picrosirius red staining and increased expression of fibrotic genes including Col3a1 and Lox. Overall, our data indicated that mice displaying behavioral characteristics associated with PTSD present with sex-dependent diastolic dysfunction likely due, at least in part, to an activation of cardiac fibrosis.

Omentin-1 as a promising biomarker and therapeutic target in hypertension and heart failure: a comprehensive review

Omentin-1, a novel adipocytokine predominantly secreted by visceral adipose tissue, has emerged as a significant factor in cardiovascular health, particularly regarding hypertension (HTN) and heart failure (HF). This manuscript investigates the multifaceted roles of omentin-1 in these conditions, emphasizing its protective effects on vascular function and its potential as both a biomarker and therapeutic target. Clinical studies indicate that reduced circulating levels of omentin-1 are associated with metabolic syndrome (MetS) and increased cardiovascular risk, while animal studies demonstrate its ability to ameliorate endothelial dysfunction and lower blood pressure. Omentin-1 exerts its beneficial effects through various signaling pathways, including AMP-activated protein kinase (AMPK) and protein kinase B (Akt), thereby promoting vasodilation, enhancing insulin sensitivity, and mitigating inflammation. In the context of HF, particularly heart failure with preserved ejection fraction (HFpEF), omentin-1 levels exhibit a negative correlation with diastolic dysfunction and inflammatory markers, suggesting its role in cardiac protection. Additionally, the manuscript discusses the implications of omentin-1 in managing obesity-related cardiovascular diseases and its potential utility as a prognostic marker for adverse outcomes in HF patients. Collectively, omentin-1 represents a promising avenue for research in cardiovascular health, with the potential to inform novel therapeutic strategies aimed at improving outcomes in patients with HTN and HF. Further research is necessary to elucidate the details of omentin-1 function and evaluate its potential in the treatment of cardiovascular disease.

Omentin-1 modulates interleukin expression and macrophage polarization: Implications for rheumatoid arthritis therapy

BACKGROUND

Rheumatoid arthritis (RA) is a systemic inflammatory and autoimmune disorder in which monocytes/macrophage infiltrate synovial membrane, differentiating into the pro- and anti-inflammatory M1 and M2 macrophage phenotypes. Omentin-1 is one of the adipokines that has anti-inflammatory and immunomodulatory effects; nevertheless, investigators have yet to elucidate the function of omentin-1 in RA development. It is still unclear how omentin-1 affects human autoimmune disease and what its beneficial role is. Thus, we show that omentin-1 exhibits a therapeutic effect on RA.

METHODS

Utilizing patient or animal tissue, MH7A cell-line, ELISA, and qPCR, we examined the expression of omentin-1 and inflammatory cytokines in the GEO databases. Omentin-1's effects on macrophage polarization were investigated using Immunofluorescence staining (IF) and qPCR. Additionally, the method by which omentin-1 regulates interleukins was discovered by IF labeling for STAT6 translocation, siRNA transfection, IPA software using several and pharmacological inhibitors. Omentin-1's effects were examined in an in vivo investigation using the type II collagen-induced arthritis model, micro-CT, and histological evaluation.

RESULTS

Results from the GSE97779 dataset and patients' tissues discovered that the level of omentin-1 and M2 macrophage markers are downregulated in human RA tissue samples compared to healthy tissue and negatively correlated with the expression of pro-inflammatory interleukins (ILs) and M1 macrophage. Stimulation of RA synovial fibroblasts with omentin-1 augmented IL-4 synthesis and subsequently enhanced anti-inflammatory ability as well as M2 polarization. The STAT6 transactivation through AMPK, PI3K, ERK, and JAK cascades regulates omentin-1-induced promotion of IL-4. Importantly, intra-articular injection of omentin-1 blocked collagen-induced arthritis-augmented pro-inflammatory response, cartilage degradation, and bone loss through upregulating IL-4 and M2 macrophages in vivo.

CONCLUSION

Our findings support a potential therapy goal for RA and a tenable mechanism to explain the relationship between omentin-1.

Omentin-General Overview of Its Role in Obesity, Metabolic Syndrome and Other Diseases; Problem of Current Research State

Background: Omentin (omentin-1, intelectin-1, ITLN-1) is an adipokine considered to be a novel substance. Many chronic, inflammatory, or civilization diseases are linked to obesity, in which omentin plays a significant role. Methods: MEDLINE and SCOPUS databases were searched using the keywords "omentin" or "intelectin-1". Then the most recent articles providing new perspectives on the matter and the most important studies, which revealed crucial insight, were selected to summarize the current knowledge on the role of omentin in a literature review. Results and Conclusions: The valid role of this adipokine is evident in the course of metabolic syndrome. In most cases, elevated omentin expression is correlated with the better course of diseases, including: type 2 diabetes mellitus, polycystic ovary syndrome, rheumatoid arthritis, metabolic dysfunction-associated steatotic liver disease, Crohn's disease, ulcerative colitis, atherosclerosis, or ischemic stroke, for some of which it can be a better marker than the currently used ones. However, results of omentin studies are not completely one-sided. It was proven to participate in the development of asthma and atopic dermatitis and to have different concentration dynamics in various types of tumors. All of omentin's effects and properties make it an attractive subject of research, considering still unexplored inflammation mechanisms, in which it may play an important role. Omentin was proven to prevent osteoarthritis, hepatocirrhosis, and atherosclerosis in mouse models. All of the above places omentin among potential therapeutic products, and not only as a biomarker. However, the main problems with the omentin's research state are the lack of standardization, which causes many contradictions and disagreements in this field.

In vitro effect of omentin-1 on level of other adipokines in granulosa cells from ovaries of Large White and Meishan pigs

Omentin-1, also known as intelectin-1 (ITLN1), is an adipokine produced by visceral adipose tissue and effect on improve insulin sensitivity, regulate energy metabolism and reproduction. Our previously data has shown that ITLN1 expression in porcine ovarian follicles is influenced by both the level of adiposity and the phase of the estrous cycle. Additionally, recent studies have indicated variations in the serum levels of adipokines in pigs with higher fat content, suggest their common interaction. It was therefore hypothesized that ITLN1 regulates the levels of other adipokines and their receptors in the ovary of pigs with different fat content. The aim of this study was to investigate the in vitro effect of ITLN1 (10-100 ng/mL) on the levels of other adipokines, namely adiponectin, apelin, leptin, chemerin, resistin, visfatin, and vaspin in the culture medium, assessed by ELISA. In addition, the effect of ITLN1 on the mRNA expression of the above-mentioned adipokines with their receptors was investigated using RT-qPCR in granulosa cells (Gc) from normal weight Large White (LW) and fat Meishan (MS) pigs on days 10-12 of the estrous cycle. The results showed that ITLN1 reduced apelin levels, increased leptin, and had no effect on vaspin in the culture medium. ITLN1 was found to have a modulating effect on the mRNA expression of the other adipokines with their receptors in porcine Gc. It can, therefore, be proposed that ITLN1 represents a previously unidentified auto- and paracrine regulator of the functions of ovarian microenvironmental compartments in different types of pig breeds.

Omentin-1, a Protective Adipokine for Irritable Bowel Syndrome

Introduction

Irritable bowel syndrome (IBS) is characterized by patients' high level of suffering. There is increasing evidence for involvement of the immune system in this disease. Adipokines have been reported to be critical immunoregulators in many clinical conditions, including gastrointestinal (GI) inflammatory diseases. Our study aimed to investigate associations of omentin-1 (a newly discovered adipokine) with IBS.

Methods

In the current study, serum levels of omentin-1 were measured in 209 patients with IBS (including three subtypes) and 188 healthy controls by enzyme-linked immunosorbent assay (ELISA). The somatic symptoms of IBS were determined by the 5-item IBS symptoms severity score (IBS-SSS), quality of life (QOL) by 34-item IBS-QOL questionnaire, and psychological disorders by Patient Health Questionnaire (PHQ-9), Hospital Anxiety and Depression Scale (HADS), Visceral Sensitivity Index (VSI). Therapeutic effect of omentin-1 for IBS was investigated in a 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced IBS mouse model.

Results

We found that serum levels of omentin-1 were significantly decreased in patients with the diarrhea-predominant IBS (IBS-D) subtype (not the constipation or alternating subtype) compared to those in healthy subjects. Patients with lower serum omentin-1 levels suffered from higher severity of somatic symptoms (abdominal pain and distention, flatulence, rumbling), lower QOL, and worse psychological status. In a one-year follow-up, serum omentin-1 levels showed potential to reflect the disease progression. Additionally, lower omentin-1 levels were found to be accompanied with higher levels of serum pro-inflammatory cytokine concentrations in patients with IBS-D. Supplement of omentin-1 was protective against visceral hypersensitivity and mucosal inflammation in an IBS mouse model.

Discussion

Our findings highlight the potential value of serum omentin-1 levels as an innovative biomarker in IBS, emphasizing its significance in improving clinical treatment and management of the disease.

pH-sensitive nano-drug delivery systems dual-target endothelial cells and macrophages for enhanced treatment of atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease characterized by vascular endothelial dysfunction. In the early stage of the disease, endothelial cell injury induces the infiltration of inflammatory macrophages, which secrete large amounts of inflammatory factors, further aggravating endothelial cell dysfunction and exacerbating the disease. Therefore, it is promising for co-targeting endothelial cells and macrophages further regulating the inflammatory microenvironment and endothelial cell function for effective treatment. The current nano-drug delivery system (NDDS) for AS treatment is mainly focused on anti-inflammatory therapy, while ignoring the potential value of suppressing inflammation and simultaneously improving vascular endothelial function. In this study, a pH-responsive dual-targeted NDDS based on plaque microenvironment, BC@CS/cRGD NPs, was prepared by combining baicalin (BC) with chondroitin sulfate (CS) through amidation reaction, and further modified with a targeting group cRGD peptide. In vitro release experiments illustrated a faster release of the nanoparticle at pH 5.0 than at pH 7.4. Meanwhile, in vitro cellular experiments demonstrated its ability to target activated endothelial cells and macrophages. In a mouse model of AS, BC@CS/cRGD NPs accumulated at plaque sites and effectively attenuated the plaque progression. In conclusion, this pH-sensitive BC@CS/cRGD NPs offered a very potential strategy for modulating endothelial dysfunction and inflammatory microenvironment for the treatment of AS.

Omentin-1 mitigates non-alcoholic fatty liver disease by preserving autophagy through AMPKα/mTOR signaling pathway

Adipose tissue-derived adipokines facilitate inter-organ communication between adipose tissue and other organs. Omentin-1, an adipokine, has been implicated in the regulation of glucose and insulin metabolism. However, limited knowledge exists regarding the regulatory impact of endogenous omentin-1 on hepatic steatosis. C57BL/6J mice were fed with high-fat diet (HFD) for 8 weeks to induce nonalcoholic fatty liver disease (NAFLD), while HepG2 cells were exposed to a 0.1 mM free fatty acid (FFA) mixture for 24 h to induce hepatic steatosis. Both the mice and cells were treated with omentin-1, and the therapeutic effects as well as the underlying molecular mechanisms were investigated. Our data demonstrate that omentin-1 attenuates weight and fat mass gain, preserves glucose homeostasis, normalizes the expression of lipogenesis-related proteins, and alleviates hepatic lipid accumulation in HFD fed mice. Furthermore, omentin-1 normalized AMPKα/mTOR signaling and preserves autophagy in these mice. In vitro, omentin-1 also preserves autophagy and attenuates lipid accumulation by normalizing AMPKα/mTOR signaling in a cell model of FFA treated HepG2 cells. However, inhibition of AMPK with Compound C or AMPKα whole-body knockout reverses the above beneficial effects of omentin-1. The present study demonstrates that omentin-1 exerts a preventive effect on non-alcoholic fatty liver disease (NAFLD) by preserving autophagy through normalizing the AMPKα/mTOR pathway, thereby suggesting its potential as a promising therapeutic agent against NAFLD.

Omentin-1 and diabetes: more evidence but far from enough

AIMS AND BACKGROUND

Omentin-1 (oment-1) is a type of adipokines that is mainly expressed in visceral fat tissue. Based on accumulating evidence, oment-1 is closely related to diabetes and its complications. However, so far data about oment-1 and diabetes is fragmented. In this review, we focus on the role of oment-1 on diabetes, including its possible signalling pathways, the correlation of circulating omens-1 levels with diabetes and its complications.

METHODS

The web of PubMed was searched for articles of relevant studies published until February, 2023.

RESULTS AND CONCLUSIONS

Oment-1 might exert its effects by inhibiting the NF-κB pathway and activating the Akt and AMPK-dependent pathways. The level of circulating oment-1 is negatively correlated with the occurrence of type 2 diabetes and some complications, including diabetic vascular disease, cardiomyopathy, and retinopathy, which can be affected by anti-diabetic therapies. Oment-1 could be a promising marker for screening and targeted therapy for diabetes and its complications; however, more studies are still needed.

Omentin Increases Glucose Uptake, but Not Insulin Sensitivity in Human Myotubes Dependent on Extracellular Lactotransferrin

INTRODUCTION

Omentin (intelectin-1) is an adipokine produced by the stromal vascular fraction of visceral adipose tissue and has been positively associated with insulin sensitivity. The underlying mechanism of action, however, is largely unknown. It has been described that omentin may increase insulin sensitivity and glucose uptake of adipocytes, but effects on other insulin-sensitive tissues such as skeletal muscle are unexplored. We therefore investigated effects of omentin on insulin sensitivity and metabolism of primary human myotubes.

METHODS

Primary human myotubes were treated with 0.5 or 2 µg/mL omentin and subsequently protein detection, glucose uptake assay, lactate assay, and lipidomics analysis were performed.

RESULTS

Omentin did not affect skeletal muscle insulin signaling, as assessed by basal and insulin-stimulated phosphorylation of IRS1 and AKT. Omentin increased basal, but not insulin-stimulated glucose uptake. While increased glycolytic activity was confirmed by elevated lactate release after omentin treatment, effects on cellular lipid composition were limited to an increase in total triacylglycerol concentration. Increased glucose uptake by omentin was counteracted by addition of extracellular lactotransferrin, which can bind to omentin.

CONCLUSIONS

Overall, increased basal glucose uptake in skeletal muscle cells suggests differential effects of omentin on insulin-sensitive tissues. Moreover, an involvement of lactotransferrin in omentin's mechanism of action may partially explain contradictory results of epidemiological studies on the role of omentin in different diseases.

The Impact of the Endocrine and Immunological Function of Adipose Tissue on Reproduction in Women with Obesity

Obesity, which leads to metabolic dysregulation and body function impairment, emerges as one of the pressing health challenges worldwide. Excessive body fat deposits comprise a dynamic and biologically active organ possessing its own endocrine function. One of the mechanisms underlying the pathophysiology of obesity is low-grade systemic inflammation mediated by pro-inflammatory factors such as free fatty acids, lipopolysaccharides, adipokines (including leptin, resistin and visfatin) and cytokines (TNF-α, IL-1β, Il-6), which are secreted by adipose tissue. Together with obesity-induced insulin resistance and hyperandrogenism, the exacerbated immune response has a negative impact on the hypothalamic-pituitary-gonadal axis at all levels and directly affects reproduction. In women, it results in disrupted ovarian function, irregular menstrual cycles and anovulation, contributing to infertility. This review focuses on the abnormal intracellular communication, altered gene expression and signaling pathways activated in obesity, underscoring its multifactorial character and consequences at a molecular level. Extensive presentation of the complex interplay between adipokines, cytokines, immune cells and neurons may serve as a foundation for future studies in search of potential sites for more targeted treatment of reproductive disorders related to obesity.

Adipokines in pregnancy

Reproductive success consists of a sequential events chronology, starting with the ovum fertilization, implantation of the embryo, placentation, and cellular processes like proliferation, apoptosis, angiogenesis, endocrinology, or metabolic changes, which taken together finally conduct the birth of healthy offspring. Currently, many factors are known that affect the regulation and proper maintenance of pregnancy in humans, domestic animals, or rodents. Among the determinants of reproductive success should be distinguished: the maternal microenvironment, genes, and proteins as well as numerous pregnancy hormones that regulate the most important processes and ensure organism homeostasis. It is well known that white adipose tissue, as the largest endocrine gland in our body, participates in the synthesis and secretion of numerous hormones belonging to the adipokine family, which also may regulate the course of pregnancy. Unfortunately, overweight and obesity lead to the expansion of adipose tissue in the body, and its excess in both women and animals contributes to changes in the synthesis and release of adipokines, which in turn translates into dramatic changes during pregnancy, including those taking place in the organ that is crucial for the proper progress of pregnancy, i.e. the placenta. In this chapter, we are summarizing the current knowledge about levels of adipokines and their role in the placenta, taking into account the physiological and pathological conditions of pregnancy, e.g. gestational diabetes mellitus, preeclampsia, or intrauterine growth restriction in humans, domestic animals, and rodents.

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.

Influence of Adipokines on Metabolic Dysfunction and Aging

Currently, 30% of the global population is overweight or obese, with projections from the World Obesity Federation suggesting that this figure will surpass 50% by 2035. Adipose tissue dysfunction, a primary characteristic of obesity, is closely associated with an increased risk of metabolic abnormalities, such as hypertension, hyperglycemia, and dyslipidemia, collectively termed metabolic syndrome. In particular, visceral fat accretion is considered as a hallmark of aging and is strongly linked to higher mortality rates in humans. Adipokines, bioactive peptides secreted by adipose tissue, play crucial roles in regulating appetite, satiety, adiposity, and metabolic balance, thereby rendering them key players in alleviating metabolic diseases and potentially extending health span. In this review, we elucidated the role of adipokines in the development of obesity and related metabolic disorders while also exploring the potential of certain adipokines as candidates for longevity interventions.

Roles of Integrin in Cardiovascular Diseases: From Basic Research to Clinical Implications

Cardiovascular diseases (CVDs) pose a significant global health threat due to their complex pathogenesis and high incidence, imposing a substantial burden on global healthcare systems. Integrins, a group of heterodimers consisting of α and β subunits that are located on the cell membrane, have emerged as key players in mediating the occurrence and progression of CVDs by regulating the physiological activities of endothelial cells, vascular smooth muscle cells, platelets, fibroblasts, cardiomyocytes, and various immune cells. The crucial role of integrins in the progression of CVDs has valuable implications for targeted therapies. In this context, the development and application of various integrin antibodies and antagonists have been explored for antiplatelet therapy and anti-inflammatory-mediated tissue damage. Additionally, the rise of nanomedicine has enhanced the specificity and bioavailability of precision therapy targeting integrins. Nevertheless, the complexity of the pathogenesis of CVDs presents tremendous challenges for monoclonal targeted treatment. This paper reviews the mechanisms of integrins in the development of atherosclerosis, cardiac fibrosis, hypertension, and arrhythmias, which may pave the way for future innovations in the diagnosis and treatment of CVDs.

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.

Use of Machine Learning for the Identification and Validation of Immunogenic Cell Death Biomarkers and Immunophenotypes in Coronary Artery Disease

Objective

Immunogenic cell death (ICD) is part of the immune system's response to coronary artery disease (CAD). In this study, we bioinformatically evaluated the diagnostic and therapeutic utility of immunogenic cell death-related genes (IRGs) and their relationship with immune infiltration features in CAD.

Methods

We acquired the CAD-related datasets GSE12288, GSE71226, and GSE120521 from the Gene Expression Omnibus (GEO) database and the IRGs from the GeneCards database. After identifying the immune cell death-related differentially expressed genes (IRDEGs), we developed a risk model and detected immune subtypes in CAD. IRDEGs were identified using least absolute shrinkage and selection operator (LASSO) analysis. Using a nomogram, we confirmed that both the LASSO model and ICD signature genes had good diagnostic performance.

Results

There was a high degree of coincidence and immune representativeness between two CAD groups based on characteristic genes and hub genes. Hub genes were associated with the interaction of neuroactive ligands with receptors and cell adhesion receptors. The two groups differed in terms of adipogenesis, allograft rejection, and apoptosis, as well as the ICD signature and hub gene expression levels. The two CAD-ICD subtypes differed in terms of immune infiltration.

Conclusion

Quantitative real-time PCR (qRT-PCR) correlated CAD with the expression of OAS3, ITGAV, and PIBF1. The ICD signature genes are candidate biomarkers and reference standards for immune grouping in CAD and can be beneficial in precise immune-targeted therapy.

Association between omentin-1 and heart failure with preserved ejection fraction in Chinese elderly patients

BACKGROUND

Omentin-1 is a novel adipokine and is associated with chronic inflammation and cardiovascular diseases. However, it remains unclear whether omentin-1 levels are associated with diagnostic significance in elderly patients with heart failure with preserved ejection fraction (HFpEF). This study aimed to investigate the correlation between omentin-1 and HFpEF in Chinese elderly patients.

HYPOTHESIS

Omentin-1 may be invovled in HFpEF and there may be a difference of omentin-1 levels between HFpEF and control.

METHODS

217 subjects were selected, including 115 patients with HFpEF and 102 control subjects. Enzyme-linked immuno sorbent assay (ELISA) was used to detect plasma levels of omentin-1, tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). The receiver operating characteristics (ROC) curve was used to examine the diagnostic performance of omentin-1 in HFpEF.

RESULTS

The levels of omentin-1 decreased significantly in the HFpEF group (14.02 ± 8.35 vs. 19.74 ± 8.45 ng/mL, p < .001), while NT-proBNP, IL-6, and TNF-α levels were significantly increased in the HFpEF group compared with the control group. Spearman correlation analysis showed that omentin-1 levels were negatively correlated with E/e' (r = -.340, p < .001). The multivariate logistic regression analysis indicated that omentin-1 was an independent protective factor for HFpEF (odd ratio = 0.948, 95% confidence interval [CI] 0.905-0.993, p = .025). Omentin-1 levels were negatively correlated with NT-proBNP (r = -.273, p < .001) and TNF-α (r = -.221, p = .001). Diagnostic efficiency by ROC curve analysis in the patients with HFpEF showed that the area under the curve (AUC) for omentin-1 was equivalent to NT-proBNP (AUC: 0.734, 95%CI 0.667-0.802; AUC: 0.800, 95%CI 0.738-0.861). Subgroup analysis showed that in the patients between the age of 70 and 80, the predictive capability of omentin-1 was stronger than NT-proBNP (AUC: 0.809, 95%CI 0.680-0.937; AUC: 0.674, 95%CI 0.514-0.833).

CONCLUSIONS

Omentin-1 levels which were associated with inflammation, were decreased in the HFpEF patients. It could be regarded as a valuable biomarker for the occurrence and development of HFpEF in elderly patients.

Plasma level of omentin-1, its expression, and its regulation by gonadotropin-releasing hormone and gonadotropins in porcine anterior pituitary cells

Omentin-1 (OMNT1) is an adipokine involved in the regulation of energy metabolism, insulin sensitivity, and reproduction. The present study was the first to investigate the plasma levels and expression of OMNT1 in the anterior pituitary (AP) gland on days 2-3, 10-12, 14-16, and 17-19 of the estrous cycle of normal-weight Large White (LW) and fat Meishan (MS) pigs. Next, we determined the effect of GnRH, LH, and FSH on the OMNT1 levels in cultured AP cells. The gene and protein expression of OMNT1 in AP fluctuated during the estrous cycle, with a higher expression in MS than in LW (except on days 10-12). However, plasma levels of OMNT1 were higher in LW than in MS. OMNT1 was localized in somatotrophs, lactotrophs, thyrotrophs, and gonadotrophs. In LW pituitary cells, GnRH and gonadotropins stimulated OMNT1 protein expression (except FSH on days 14-16) and had no effect on OMNT1 levels in the culture medium. In MS pituitary cells, we observed that GnRH and LH increased while FSH decreased OMNT1 protein expression. These findings showed OMNT1 expression and regulation in the porcine AP and suggested that OMNT1 could be a new player modifying the pituitary functions.

Inflammation-Involved Proteins in Blood Serum of Cataract Patients-A Preliminary Study

Approximately 50% of all global blindness is caused by cataract in adults aged ≥50 years. The mechanisms of the disease are most arguably related to a redox imbalance and inflammation; therefore, the aim of the study was to evaluate the processes associated with inflammation in cataract patients. Twenty-four patients aged 22-60 years (62.5% females) participated in the study, with 33 controls aged 28-60 years (66.7% females). Venous blood serum of the subjects was examined for alpha 1-antitrypsin, as well as selected lysosomal enzymes and adipokines. The activities of lysosomal enzymes, as well as the activity of alpha 1-antitrypsin and the concentrations of c-reactive protein and leptin, were similar in the patients versus the controls. The concentrations of interleukin 6 and resistin were lower, in turn, whereas omentin-1 and adiponectin were higher. Moreover, the study revealed the existence of many linear relationships between the parameters, including multiple linear regression, especially gender-wise. No systemic inflammation was probably noted in the cataract patients tested; nevertheless, the deregulation of adiponectin, omentin-1 and resistin secretion was observed.

Role of omentin-1 in susceptibility to anxiety and depression like behaviors

Neuro-inflammation and blood-brain barrier (BBB) dysfunction are associated with depression. Evidence shows that adipokines enter the brain from the circulation, which regulates depressive behaviors. Omentin-1 is a newly identified adipocytokine that has anti-inflammatory effects, but little is known about its role in neuro-inflammation and mood-relevant behavior. Our results showed omentin-1 knockout mice (Omentin-1-/-) increased susceptibility to anxiety and depressive-like behaviors, which are associated with abnormalities of cerebral blood flow (CBF) and impaired BBB permeability. Moreover, omentin-1 depletion significantly increased hippocampal pro-inflammatory cytokines (IL-1β, TNFα, IL-6), caused microglial activation, inhibited hippocampus neurogenesis, and resulted in autophagy impairment by dysregulating ATG genes. Omentin-1 deficiency also sensitized mice to the behavioral changes induced by lipopolysaccharide (LPS), suggesting that omentin-1 could rescue neuro-inflammation by acting as an anti-depressant. Our in vitro microglia cell culture data confirmed that recombinant omentin-1 suppresses microglial activation and pro-inflammatory cytokine expression induced by LPS. Our study suggests that omentin-1 can be used as a promising therapeutic agent for the prevention or treatment of depression by providing a barrier-promoting effect and an endogenous anti-inflammatory balance to downregulate the proinflammatory cytokines.

Human Omentin-1 Administration Ameliorates Hypertensive Complications without Affecting Hypertension in Spontaneously Hypertensive Rats

Hypertension is one of the major risk factors for cardiovascular diseases and is caused by various abnormalities including the contractility of blood vessels. Spontaneously hypertensive rats (SHR), whose systemic blood pressure increases with aging, are a frequently used animal model for investigating essential hypertension and related complications in humans due to the damage of several organs. Human omentin-1 is an adipocytokine consisting of 313 amino acids. Serum omentin-1 levels decreased in hypertensive patients compared with normotensive controls. Furthermore, omentin-1 knockout mice showed elevated blood pressure and impaired endothelial vasodilation. Taken together, we hypothesized that adipocytokine, human omentin-1 may improve the hypertension and its complications including heart and renal failure in the aged SHR (65-68-weeks-old). SHR were subcutaneously administered with human omentin-1 (18 μg/kg/day, 2 weeks). Human omentin-1 had no effect on body weight, heart rate, and systolic blood pressure in SHR. The measurement of isometric contraction revealed that human omentin-1 had no influence on the enhanced vasocontractile or impaired vasodilator responses in the isolated thoracic aorta from SHR. On the other hand, human omentin-1 tended to improve left ventricular diastolic failure and renal failure in SHR. In summary, human omentin-1 tended to improve hypertensive complications (heart and renal failure), while it had no influence on the severe hypertension in the aged SHR. The further study of human omentin-1 may lead to the development of therapeutic agents for hypertensive complications.

Intelectin-1 binds and alters the localization of the mucus barrier-modifying bacterium Akkermansia muciniphila

Intelectin-1 (ITLN1) is a lectin secreted by intestinal epithelial cells (IECs) and upregulated in human ulcerative colitis (UC). We investigated how ITLN1 production is regulated in IECs and the biological effects of ITLN1 at the host-microbiota interface using mouse models. Our data show that ITLN1 upregulation in IECs from UC patients is a consequence of activating the unfolded protein response. Analysis of microbes coated by ITLN1 in vivo revealed a restricted subset of microorganisms, including the mucolytic bacterium Akkermansia muciniphila. Mice overexpressing intestinal ITLN1 exhibited decreased inner colonic mucus layer thickness and closer apposition of A. muciniphila to the epithelial cell surface, similar to alterations reported in UC. The changes in the inner mucus layer were microbiota and A. muciniphila dependent and associated with enhanced sensitivity to chemically induced and T cell-mediated colitis. We conclude that by determining the localization of a select group of bacteria to the mucus layer, ITLN1 modifies this critical barrier. Together, these findings may explain the impact of ITLN1 dysregulation on UC pathogenesis.

Lectin recruits pathogenic bugs

Colitis is an irritable bowel disorder affecting about 7 million patients worldwide, but the causes are diverse and not fully understood. In this issue, Matute et al. (2022. J. Exp. Med.https://doi.org/10.1084/jem.20211938) found that a stress-induced lectin, intelectin-1, recruits pathogenic bacteria to the gut and exacerbates colitis.

The Role of Adipokines in Inflammatory Mechanisms of Obesity

Adipokines are currently widely studied cellular signaling proteins produced by adipose tissue and involved in various processes, including inflammation; energy and appetite modulation; lipid and glucose metabolism; insulin sensitivity; endothelial cell functioning; angiogenesis; the regulation of blood pressure; and hemostasis. The current review attempted to highlight the key functions of adipokines in the inflammatory mechanisms of obesity, its complications, and its associated diseases. An extensive search for materials on the role of adipokines in the pathogenesis of obesity was conducted online using the PubMed and Scopus databases until October 2022.

The Complex Roles of Adipokines in Polycystic Ovary Syndrome and Endometriosis

Polycystic ovary syndrome (PCOS) and endometriosis are frequent diseases of the female reproductive tract causing high morbidity as they can significantly affect fertility and quality of life. Adipokines are pleiotropic signaling molecules secreted by white or brown adipose tissues with a central role in energy metabolism. More recently, their involvement in PCOS and endometriosis has been demonstrated. In this review article, we provide an update on the role of adipokines in both diseases and summarize previous findings. We also address the results of multi-omics approaches in adipokine research to examine the role of single nucleotide polymorphisms (SNPs) in genes coding for adipokines and their receptors, the secretome of adipocytes and to identify epigenetic alterations of adipokine genes that might be conferred from mother to child. Finally, we address novel data on the role of brown adipose tissue (BAT), which seems to have notable effects on PCOS. For this review, original research articles on adipokine actions in PCOS and endometriosis are considered, which are listed in the PubMed database.

The Effect of Mineralocorticoid Receptor 3 Antagonists on Anti-Inflammatory and Anti-Fatty Acid Transport Profile in Patients with Heart Failure

Epicardial fat thickness is associated with cardiovascular disease. Mineralocorticoid receptor antagonist (MRA), a pharmaceutical treatment for CVD, was found to have an effect on adipose tissue. Our aim was to analyse the main epicardial fat genesis and inflammation-involved cell markers and their regulation by risk factors and MRA. We included blood and epicardial or subcutaneous fat (EAT or SAT) from 71 patients undergoing heart surgery and blood from 66 patients with heart failure. Cell types (transcripts or proteins) were analysed by real-time polymerase chain reaction or immunohistochemistry. Plasma proteins were analysed by Luminex technology or enzyme-linked immunoassay. Our results showed an upregulation of fatty acid transporter levels after aldosterone-induced genesis. The MRA intake was the main factor associated with lower levels in epicardial fat. On the contrary, MRA upregulated the levels and its secretion of the anti-inflammatory marker intelectin 1 and reduced the proliferation of epicardial fibroblasts. Our results have shown the local MRA intake effect on fatty acid transporters and anti-inflammatory marker levels and the proliferation rate on epicardial fat fibroblasts. They suggest the role of MRA on epicardial fat genesis and remodelling in patients with cardiovascular disease. Translational perspective: the knowledge of epicardial fat genesis and its modulation by drugs might be useful for improving the treatments of cardiovascular disease.

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 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.