Metabolic Regulation of Adipose Tissue Macrophage Function in Obesity and Diabetes

Osteogenic effect and mechanism of IL-10 in diabetic rat jaw defect mode

OBJECTIVE

The aim of this study was to investigate the effect of IL-10 on the phenotype polarization of macrophages and osteogenesis in diabetes mellitus type 2 (T2DM) rat jaw defects.

METHODS

Lipopolysaccharide (LPS) and interleukin-10 (IL-10) were chosen to induce the polarization of macrophages. In vitro assessment included wound-healing assay, western blotting, and alizarin red staining after co-culture of the bone marrow-derived mesenchymal stem cells (BMSCs) and induced macrophages. For in vivo study, IL-10 was loaded on GelMA-Heparin and applied to bone defects of the alveolar ridge in diabetic rats, while Bio-Oss Collagen, simple GelMA-Heparin, and blank control groups were set for contrast experiment. The mandibles of rats were processed for micro-computed tomography, histology, and immunohistochemistry 1 week and 4 weeks after the operation.

RESULTS

IL-10 induced expression of arginase 1, TGF-β1, EGR2, and Mannose Receptor (CD206), whereas LPS induced expression of iNOS, TNF-α, IL-6, CD80. The BMSCs co-cultured with macrophages induced by IL-10 showed increased migration, osteogenic differentiation, and mineralization in vitro. Notably, the IL-10-laden GelMA-Heparin group showed quicker new bone formation and a higher M2/M1 ratio of macrophages in the jawbone defect area compared with the control groups.

CONCLUSIONS

IL-10 can stably induce macrophages to M2 type, thereby influencing BMSCs and improving the osteogenesis of jaw bone defects.

The Expression of MAFB Gene in Circulating Monocytes Is Related to Chronic Inflammatory Status in T2DM Patients

Immune cell-mediated chronic inflammation is one of the causes of type 2 diabetes mellitus (T2DM). Therefore, identifying inflammatory markers in circulating immune cells is highly important for predicting insulin resistance (IR) and the occurrence of T2DM. In this study, we discovered that differentially expressed genes (DEGs) in peripheral blood mononuclear cells (PBMCs) from T2DM patients were associated with innate immunity and chronic inflammatory responses through bulk transcriptome sequencing (bulk RNA-seq). Gene integration analysis revealed that nine DEGs were upregulated, and receiver operating characteristic (ROC) curve analysis revealed that V-maf musculoaponeurotic fibrosarcoma oncogene homolog B (MAFB), a candidate biomarker, has a certain predictive value for T2DM. In population-based cohort studies, we found that MAFB expression was significantly upregulated in the PBMCs of T2DM patients and was significantly correlated with homeostasis model assessment of IR (HOMA-IR), tumor necrosis factor-α (TNF-α), adiponectin (Adipoq), etc. We further evaluated the sensitivity and specificity of MAFB and other clinical parameters for predicting and diagnosing T2DM and found that MAFB expression in PBMCs had a positive effect on the prediction and diagnosis of T2DM. Finally, single-cell RNA sequencing (scRNA-seq) analysis revealed that the increase in MAFB expression was mainly in nonclassical monocytes. Our results suggest that increased MAFB expression in circulating monocytes may mediate chronic inflammatory status in patients with T2DM. Therefore, MAFB gene expression in circulating monocytes has certain clinical significance for predicting and assisting in the diagnosis of T2DM.

Adipose organ dysfunction and type 2 diabetes: Role of nitric oxide

Adipose organ, historically known as specialized lipid-handling tissue serving as the long-term fat depot, is now appreciated as the largest endocrine organ composed of two main compartments, i.e., subcutaneous and visceral adipose tissue (AT), madding up white and beige/brown adipocytes. Adipose organ dysfunction manifested as maldistribution of the compartments, hypertrophic, hypoxic, inflamed, and insulin-resistant AT, contributes to the development of type 2 diabetes (T2D). Here, we highlight the role of nitric oxide (NO·) in AT (dys)function in relation to developing T2D. The key aspects determining lipid and glucose homeostasis in AT depend on the physiological levels of the NO· produced via endothelial NO· synthases (eNOS). In addition to decreased NO· bioavailability (via decreased expression/activity of eNOS or scavenging NO·), excessive NO· produced by inducible NOS (iNOS) in response to hypoxia and AT inflammation may be a critical interfering factor diverting NO· signaling to the formation of reactive oxygen and nitrogen species, resulting in AT and whole-body metabolic dysfunction. Pharmacological approaches boosting AT-NO· availability at physiological levels (by increasing NO· production and its stability), as well as suppression of iNOS-NO· synthesis, are potential candidates for developing NO·-based therapeutics in T2D.

Severity of adipose tissue dysfunction is associated with progression of pre-diabetes to type 2 diabetes: the Tehran Lipid and Glucose Study

BACKGROUND

The association of prediabetes (Pre-DM) regression and progression with visceral adiposity index (VAI) and adipose tissue dysfunction (ATD) remains to be investigated.

METHODS

The present cohort study was conducted within the framework of the Tehran Lipid and Glucose Study (TLGS) on 1458 Pre-DM cases (aged ≥ 21 years) who were followed for nine years. VAI was estimated based on waist circumference, body mass index, triglycerides, and high-density lipoprotein cholesterol. ATD status (i.e., absent, mild-moderate, and severe) was defined based on the age-stratified cutoff values of VAI. Multinomial logistic regression models with adjustment of potential confounders were used to estimate the chance of Pre-DM regression to normoglycemia or progression to T2D across ATD status.

RESULTS

During the study follow-up, 39.0% of the participants developed T2D, and 37.7% returned to normoglycemia. Compared to mild-moderate ATD, Pre-DM subjects with severe ATD had a higher risk of developing T2D by 45% (OR = 1.45, 95% CI = 11.08-1.93). Severe ATD was also associated with a decreased chance of returning to normoglycemia by 26% (OR = 0.74, 95% CI = 0.55-0.99). Participants with severe ATD had significantly higher fasting (overall mean = 111, 95% CI = 109-112 vs. 106, 95% CI = 105-108 mg/dL) and 2h-serum glucose (overall mean = 165, 95% CI = 161-168 vs. 153, 95% CI = 149-156 mg/dL) concentrations over time.

CONCLUSION

Severe ATD was associated with an elevated risk of developing T2D and longitudinal poor-glycemic controls in Pre-DM subjects. ATD may be a simple and useful index for detecting subjects at a higher risk of Pre-DM progression to T2D, allowing for timely intervention strategies.

MiR-221-3p/222-3p Cluster Expression in Human Adipose Tissue Is Related to Obesity and Type 2 Diabetes

The progression of obesity and type 2 diabetes (T2D) is intricately linked with adipose tissue (AT) angiogenesis. Despite an established network of microRNAs (miRNAs) regulating AT function, the specific role of angiogenic miRNAs remains less understood. The miR-221/222 cluster has recently emerged as being associated with antiangiogenic activity. However, no studies have explored its role in human AT amidst the concurrent development of obesity and T2D. Therefore, this study aims to investigate the association between the miR-221-3p/222-3p cluster in human AT and its regulatory network with obesity and T2D. MiR-221-3p/222-3p and their target gene (TG) expression levels were quantified through qPCR in visceral (VAT) and subcutaneous (SAT) AT from patients (n = 33) categorized based on BMI as normoweight (NW) and obese (OB) and by glycemic status as normoglycemic (NG) and type 2 diabetic (T2D) subjects. In silico analyses of miR-221-3p/222-3p and their TGs were conducted to identify pertinent signaling pathways. The results of a multivariate analysis, considering the simultaneous expression of miR-221-3p and miR-222-3p as dependent variables, revealed statistically significant distinctions when accounting for variables such as tissue depot, obesity, sex, and T2D as independent factors. Furthermore, both miRNAs and their TGs exhibited differential expression patterns based on obesity severity, glycemic status, sex, and type of AT depot. Our in silico analysis indicated that miR-221-3p/222-3p cluster TGs predominantly participate in angiogenesis, WNT signaling, and apoptosis pathways. In conclusion, these findings underscore a promising avenue for future research, emphasizing the miR-221-3p/222-3p cluster and its associated regulatory networks as potential targets for addressing obesity and related metabolic disorders.

Thou shall not heal: Overcoming the non-healing behaviour of diabetic foot ulcers by engineering the inflammatory microenvironment

Diabetic foot ulcers (DFUs) are a devastating complication for diabetic patients that have debilitating effects and can ultimately lead to limb amputation. Healthy wounds progress through the phases of healing leading to tissue regeneration and restoration of the barrier function of the skin. In contrast, in diabetic patients dysregulation of these phases leads to chronic, non-healing wounds. In particular, unresolved inflammation in the DFU microenvironment has been identified as a key facet of chronic wounds in hyperglyceamic patients, as DFUs fail to progress beyond the inflammatory phase and towards resolution. Thus, control over and modulation of the inflammatory response is a promising therapeutic avenue for DFU treatment. This review discusses the current state-of-the art regarding control of the inflammatory response in the DFU microenvironment, with a specific focus on the development of biomaterials-based delivery strategies and their cargos to direct tissue regeneration in the DFU microenvironment.

Chronic inflammation in high-fat diet-fed mice: Unveiling the early pathogenic connection between liver and adipose tissue

Obesity-induced chronic inflammation has been linked to several autoimmune diseases, including rheumatoid arthritis, type 1 diabetes, and multiple sclerosis. The underlying mechanisms are not yet fully understood, but it is believed that chronic inflammation in adipose tissue can lead to the production of pro-inflammatory cytokines and chemokines, which can trigger immune responses and contribute to the development of autoimmune diseases. However, the underlying mechanisms that lead to the infiltration of immune cells into adipose tissue are not fully understood. In this study, we observed a time-dependent response to a high-fat diet in the liver and epididymal white adipose tissue using gene set enrichment analysis. Our findings revealed a correlation between early abnormal innate immune responses in the liver and late inflammatory response in the adipose tissue, that eventually leads to systemic inflammation. Specifically, our data suggest that the dysregulated NADH homeostasis in the mitochondrial matrix, interacting with the mitochondrial translation process, could serve as a sign marking the transition from liver inflammation to adipose tissue inflammation. Taken together, our study provides valuable insights into the molecular mechanisms underlying the development of chronic inflammation and associated autoimmune diseases in obesity.

Polarization of Melatonin-Modulated Colostrum Macrophages in the Presence of Breast Tumor Cell Lines

Human colostrum and milk contain diverse cells and soluble components that have the potential to act against tumors. In breast cancer, macrophages play a significant role in immune infiltration and contribute to the progression and spread of tumors. However, studies suggest that these cells can be reprogrammed to act as an antitumor immune response. This study aimed to evaluate the levels of melatonin and its receptors, MT1 (melatonin receptor 1) and MT2 (melatonin receptor 2), in colostrum and assess the differentiation and polarization of the colostrum macrophages modulated by melatonin in the presence of breast tumor cells. Colostrum samples were collected from 116 mothers and tested for their melatonin and receptor levels. The colostrum cells were treated with or without melatonin and then cultured for 24 h in the presence or absence of breast tumor cells. The results showed that melatonin treatment increased the expression of MT1 and MT2 in the colostrum cells. Furthermore, melatonin treatment increased the percentage of M1 macrophages and decreased the percentage of M2 macrophages. When the colostrum macrophages were cocultured with breast tumor cells, melatonin reduced the percentage of both macrophage phenotypes and the cytokines tumor necrosis factor-alpha (TNF-α) and interleukin 8 (IL-8). These data suggest that melatonin can regulate the inflammatory process via M1 macrophages in the tumor microenvironment and, simultaneously, the progression of M2 macrophages that favor tumorigenesis.

Apocynin alleviates weight gain and obesity-induced adipose tissue inflammation in high-fat diet-fed C57BL/6 mice

Obesity involves chronic low-grade inflammation within adipose tissue. Apocynin (APO) is a therapeutic agent for the treatment of inflammatory diseases. Therefore, the present study aimed to investigate whether APO can reduce weight gain and obesity-induced adipose tissue inflammation. C57BL/6 mice were administered APO or orlistat (Orli) as a positive control with a high-fat diet (HFD) for 12 weeks. Lipopolysaccharide-stimulated 3T3-L1 adipocytes were used for the in vitro study. Our results showed a significantly lower white adipose tissue (WAT) mass index in 10 mg/kg APO-treated mice than in 20 mg/kg Orli-treated mice. Moreover, the protein expression of adipose triglyceride lipase, fatty acid synthase, sterol regulatory element-binding transcription factor 1, and peroxisome proliferator-activated receptor γ was reversed in the WAT of 10 mg/kg APO-treated mice. Furthermore, APO reduced the expression of the macrophage marker F4/80, decreased the mRNA levels of tumor necrosis factor-α and monocyte chemoattractant protein-1, and increased the mRNA levels of interleukin-10 in WAT. APO decreased the phosphorylation of c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p65 in vivo and in vitro. Notably, APO had a stronger effect on the amelioration of adipose tissue inflammation than Orli did. Our findings lay the foundation for research on the use of APO as an agent to ameliorate weight gain and obesity-induced inflammatory diseases.

Research progress into adipose tissue macrophages and insulin resistance

In recent years, there has been an increasing incidence of metabolic syndrome, type 2 diabetes, and cardiovascular events related to insulin resistance. As one of the target organs for insulin, adipose tissue is essential for maintaining in vivo immune homeostasis and metabolic regulation. Currently, the specific adipose tissue mechanisms involved in insulin resistance remain incompletely understood. There is increasing evidence that the process of insulin resistance is mostly accompanied by a dramatic increase in the number and phenotypic changes of adipose tissue macrophages (ATMs). In this review, we discuss the origins and functions of ATMs, some regulatory factors of ATM phenotypes, and the mechanisms through which ATMs mediate insulin resistance. We explore how ATM phenotypes contribute to insulin resistance in adipose tissue. We expect that modulation of ATM phenotypes will provide a novel strategy for the treatment of diseases associated with insulin resistance.

Insights into the Role of Plasmatic and Exosomal microRNAs in Oxidative Stress-Related Metabolic Diseases

A common denominator of metabolic diseases, including type 2 diabetes Mellitus, dyslipidemia, and atherosclerosis, are elevated oxidative stress and chronic inflammation. These complex, multi-factorial diseases are caused by the detrimental interaction between the individual genetic background and multiple environmental stimuli. The cells, including the endothelial ones, acquire a preactivated phenotype and metabolic memory, exhibiting increased oxidative stress, inflammatory gene expression, endothelial vascular activation, and prothrombotic events, leading to vascular complications. There are different pathways involved in the pathogenesis of metabolic diseases, and increased knowledge suggests a role of the activation of the NF-kB pathway and NLRP3 inflammasome as key mediators of metabolic inflammation. Epigenetic-wide associated studies provide new insight into the role of microRNAs in the phenomenon of metabolic memory and the development consequences of vessel damage. In this review, we will focus on the microRNAs related to the control of anti-oxidative enzymes, as well as microRNAs related to the control of mitochondrial functions and inflammation. The objective is the search for new therapeutic targets to improve the functioning of mitochondria and reduce oxidative stress and inflammation, despite the acquired metabolic memory.

Role of obesity related inflammation in pathogenesis of peripheral artery disease in patients of type 2 diabetes mellitus

Objective

Type 2 diabetes mellitus (T2DM) has emerged as one of the greatest global health challenges of twenty-first century. Visceral obesity is one of the most important determinant of insulin resistance (IR) as well as T2DM complications. Therefore this review focuses on the molecular mechanism of obesity induced inflammation, signaling pathways contributing to diabetes, as well as role of lifestyle interventions and medical therapies in the prevention and management of T2DM.

Method

Articles were searched on digital data base PubMed, Cochrane Library, and Web of Science. The key words used for search included Type 2 diabetes mellitus, obesity, insulin resistance, vascular inflammation and peripheral arterial disease.

Result

Visceral obesity is associated with chronic low grade inflammation and activation of immune systems which are involved in pathogenesis of obesity related IR and T2DM.

Conclusion

Metabolic dysregulation of adipose tissue leads to local hypoxia, misfolded/unfolded protein response and increased circulating free fatty acids, which in turn initiate inflammatory signaling cascades in the population of infiltrating cells. Mechanism that relates the role of adipocytokines with insulin sensitivity and glucose homeostasis might throw a light on the development of therapeutic interventions and subsequently might result in the reduction of vascular complications.

Integration of nutrigenomics, melatonin, serotonin and inflammatory cytokines in the pathophysiology of pregnancy-specific urinary incontinence in women with gestational diabetes mellitus

Gestational diabetes mellitus is an important public health problem and has been associated with the development of pregnancy-specific urinary incontinence. The interaction is related to hyperglycemia, and inflammatory and hormonal patterns, which favor functional alterations in different organs and systems. Several genes associated with human diseases have been identified and partially characterized. Most of these genes are known to cause monogenic diseases. However, about 3 % of diseases do not fit the monogenic theory due to the complex interactions between multiple genes and environmental factors, as in chronic metabolic diseases such as diabetes. The nutritional, immunological, and hormonal patterns associated with changes in maternal metabolism may influence and contribute to greater susceptibility to urinary tract disorders. However, early systematic reviews have not yielded consistent findings for these associations. This literature review summarizes important new findings from integrating nutrigenomics, hormones, and cytokines in women with Gestational diabetes mellitus and pregnancy-specific urinary incontinence. Changes in maternal metabolism due to hyperglycemia can generate an inflammatory environment with increased inflammatory cytokines. This environment modulated by inflammation can alter tryptophan uptake through food and thus influence the production of serotonin and melatonin. As these hormones seem to have protective effects against smooth muscle dysfunction and to restore the impaired contractility of the detrusor muscle, it is assumed that these changes may favor the onset of urinary incontinence specific to pregnancy.

Targeting immunometabolism during cardiorenal injury: roles of conventional and alternative macrophage metabolic fuels

Macrophages play critical roles in mediating and resolving tissue injury as well as tissue remodeling during cardiorenal disease. Altered immunometabolism, particularly macrophage metabolism, is a critical underlying mechanism of immune dysfunction and inflammation, particularly in individuals with underlying metabolic abnormalities. In this review, we discuss the critical roles of macrophages in cardiac and renal injury and disease. We also highlight the roles of macrophage metabolism and discuss metabolic abnormalities, such as obesity and diabetes, which may impair normal macrophage metabolism and thus predispose individuals to cardiorenal inflammation and injury. As the roles of macrophage glucose and fatty acid metabolism have been extensively discussed elsewhere, we focus on the roles of alternative fuels, such as lactate and ketones, which play underappreciated roles during cardiac and renal injury and heavily influence macrophage phenotypes.

Exosomes from Inflamed Macrophages Promote the Progression of Parkinson's Disease by Inducing Neuroinflammation

Inflammation is a common feature both for Parkinson's disease (PD) and obesity-associated metabolic syndromes. Inflammation mediated by inflamed macrophages in white adipose tissue plays a pivotal role for the pathogenesis of metabolic syndromes. Exosomes are important carriers connecting peripheral tissues and the central nervous system (CNS). Therefore, we speculate that exosomes derived from inflamed macrophages may be involved in the pathological progression of PD. Here, we prepared exosomes from lipopolysaccharide (LPS) or interferon gamma (IFNγ) treated macrophages (inflamed macrophages) and examined their potential roles in PD. Our data showed that exosomes from inflamed macrophages stimulate proinflammatory cytokine expression in primary microglia and astrocytes. In vivo, inflamed macrophage exosomes induce behavioral defects in mice as evidenced by shortened duration in the rotarod test and prolonged latency in the pole test. The treatment of exosomes also reduces tyrosine hydroxylase (TH) positive cells in the substantia nigra pars compacta (SNpc) and striatum. All these PD-like phenotypes are likely due to the activation of microglia and astrocytes induced by exosomes from inflamed macrophages. Exosome sequencing, together with bioinformatics analysis and functional studies, revealed that exosomal miRNAs such as miR-155-5p are likely a key factor for inducing an inflammatory response in glial cells. These results indicate that exosomes derived from inflamed macrophages are likely a causative factor for developing PD. In this regard, inflamed macrophage exosomes might be a linker transducing the peripheral tissue inflammation into the CNS.

Role of Macrophage in Type 2 Diabetes Mellitus: Macrophage Polarization a New Paradigm for Treatment of Type 2 Diabetes Mellitus

Metabolic diseases such as type 2 diabetes mellitus are usually associated with meta-inflammation. β-cell failure is a marked feature observed in the pathogenesis of type 2 diabetes mellitus. Type 2 diabetes mellitus (T2DM) is a heterogeneous situation that is accompanied by not only defective insulin secretion but also peripheral insulin resistance. β-cells are the primary organ for insulin secretion; hence, it is crucial to maintain a significant β-cell mass in response to a variety of changes. Insulin resistance is a chief cause of T2DM, leading to increased free fatty acid (FFA) levels, which in turn elevates β-cell mass and insulin secretion as compensation for insulin insensitivity. It has recently been established that amplified numbers of innate immune cells, cytokines, and chemokines result in detrimental effects on islets in chronic conditions. Macrophage migration inhibitory factor (MIF) is the lymphokine that prevents arbitrary migration of macrophages and assembles macrophages at inflammatory loci. Inflammation is known to trigger monocytes to differentiate into macrophages. Progress of complications associated with type 2 diabetes mellitus, as indicated through recent findings, is also dependent on the buildup of macrophages in tissues vulnerable to diabetic injury. The present article scientifically evaluates the present knowledge concerning the mechanisms of monocyte and macrophage-mediated injury recruitment in complications associated with type 2 diabetes mellitus. It also describes some of the established and experimental therapies that might bring about a reduction in these inflammatory complications. Recent discoveries in the field of drug delivery have facilitated phenotype-specific targeting of macrophages. This review highlights the pathophysiology of type 2 diabetes mellitus, how macrophage induces type 2 diabetes mellitus and potential therapeutics for type 2 diabetes mellitus via macrophage-specific delivery.

Cinnamaldehyde Supplementation Reverts Endothelial Dysfunction in Rat Models of Diet-Induced Obesity: Role of NF-E2-Related Factor-2

Cinnamaldehyde (CN) is an activator of NF-E2-related factor 2 (Nrf2), which has the potential to reduce endothelial dysfunction, oxidative stress and inflammation in metabolic disorders. Our main purpose was to evaluate the effects of CN on vascular dysfunction in metabolic syndrome rats. Normal Wistar (W) rats were divided into eight groups: (1) Wistar (W) rats; (2) W rats fed with a high-fat diet (WHFD); (3) W rats fed with a sucrose diet (WS); (4) WHFD fed with a sucrose diet (WHFDS); (5) W treated with CN (WCn); (6) WS treated with CN (WSCn); (7) WHFD treated with CN (WHFDCn); (8) WHFDS treated with CN (WHFDSCn). CN treatment with 20 mg/kg/day was administered for 8 weeks. Evaluation of metabolic profile, inflammation, endothelial function, oxidative stress, eNOS expression levels and Nrf2 activation was performed. The metabolic dysfunction was greatly exacerbated in the WHFDS rats, accompanied by significantly higher levels of vascular oxidative stress, inflammation, and endothelial dysfunction. In addition, the WHFDS rats displayed significantly reduced activity of Nrf2 at the vascular level. CN significantly reverted endothelial dysfunction in the aortas and the mesenteric arteries. In addition, CN significantly decreased vascular oxidative damage, inflammation at vascular and perivascular level and up-regulated Nrf2 activity in the arteries of WHFDS rats. Cinnamaldehyde, an activator of Nrf2, can be used to improve metabolic profile, and to revert endothelial dysfunction in obesity and metabolic syndrome.

Obesity and Its Multiple Clinical Implications between Inflammatory States and Gut Microbiotic Alterations

Obesity is a chronic multifactorial disease that has become a serious health problem and is currently widespread over the world. It is, in fact, strongly associated with many other conditions, including insulin resistance, type 2 diabetes, cardiovascular and neurodegenerative diseases, the onset of different types of malignant tumors and alterations in reproductive function. According to the literature, obesity is characterized by a state of low-grade chronic inflammation, with a substantial increase in immune cells, specifically macrophage infiltrates in the adipose tissue which, in turn, secrete a succession of pro-inflammatory mediators. Furthermore, recent studies on microbiota have postulated new possible mechanisms of interaction between obesity and unbalanced nutrition with inflammation. This intestinal "superorganism" complex seems to influence not only the metabolic balance of the host but also the immune response, favoring a state of systemic inflammation and insulin resistance. This review summarizes the major evidence on the interactions between the gut microbiota, energetic metabolism and host immune system, all leading to a convergence of the fields of immunology, nutrients physiology and microbiota in the context of obesity and its possible clinical complications. Finally, possible therapeutic approaches aiming to rebalance the intestinal microbial ecosystem are evaluated to improve the alteration of inflammatory and metabolic states in obesity and related diseases.

l-Arginine supplementation regulates energy-substrate metabolism in skeletal muscle and adipose tissue of diet-induced obese rats

Dietary supplementation with l-arginine has been reported to reduce white fat mass in diet-induced obese rats and in obese humans. This study was conducted to test the hypothesis that the arginine treatment regulates glucose and fatty acid metabolism in insulin-sensitive tissues. Male Sprague–Dawley rats (4-week-old) were fed either low- or high-fat diets for 15 weeks ( n = 16/diet). Thereafter, lean or obese rats were fed their respective diets and received drinking water containing either 1.51% l-arginine-HCl or 2.55% alanine (isonitrogenous control) ( n = 8/treatment group). After 12 weeks of treatment, rats were euthanized and tissue samples were collected for biochemical assays. High-fat feeding increased the size of adipocytes isolated from retroperitoneal (RP) adipose tissue, while arginine treatment reduced their size. The total number of adipocytes in the adipose tissue did not differ among the four groups of rats. Glucose oxidation in extensor digitorum longus (EDL) muscle, soleus muscle, and RP adipose tissue were reduced in response to high-fat feeding. On the contrary, oleic acid oxidation in RP adipose tissue was enhanced in rats fed the high-fat diet. Arginine treatment stimulated both glucose and oleic acid oxidation in EDL and soleus muscles, while having no effect on glucose oxidation, oleic acid oxidation, or basal lipolysis per 106 adipocytes in RP adipose tissue. Collectively, these results indicate that oral supplementation with arginine to diet-induced obese rats promoted the oxidation of energy substrates in skeletal muscle, thereby reducing white fat in the body.

Innate Immune Memory in Monocytes and Macrophages: The Potential Therapeutic Strategies for Atherosclerosis

Atherosclerosis is a complex metabolic disease characterized by the dysfunction of lipid metabolism and chronic inflammation in the intimal space of the vessel. As the most abundant innate immune cells, monocyte-derived macrophages play a pivotal role in the inflammatory response, cholesterol metabolism, and foam cell formation. In recent decades, it has been demonstrated that monocytes and macrophages can establish innate immune memory (also termed trained immunity) via endogenous and exogenous atherogenic stimuli and exhibit a long-lasting proinflammatory phenotype. The important cellular metabolism processes, including glycolysis, oxidative phosphorylation (OXPHOS), the tricarboxylic acid (TCA) cycle, fatty acid synthesis, and cholesterol synthesis, are reprogrammed. Trained monocytes/macrophages with innate immune memory can be persistently hyperactivated and can undergo extensive epigenetic rewiring, which contributes to the pathophysiological development of atherosclerosis via increased proinflammatory cytokine production and lipid accumulation. Here, we provide an overview of the regulation of cellular metabolic processes and epigenetic modifications of innate immune memory in monocytes/macrophages as well as the potential endogenous and exogenous stimulations involved in the progression of atherosclerosis that have been reported recently. These elucidations might be beneficial for further understanding innate immune memory and the development of therapeutic strategies for inflammatory diseases and atherosclerosis.

The Significance of COVID-19 Diseases in Lipid Metabolism Pregnancy Women and Newborns

Coronavirus disease (COVID-19) is an infectious disease caused by SARS-CoV-2. Elderly people, people with immunodeficiency, autoimmune and malignant diseases, as well as people with chronic diseases have a higher risk of developing more severe forms of the disease. Pregnant women and children can becomesick, although more often they are only the carriers of the virus. Recent studies have indicated that infants can also be infected by SARS-CoV-2 and develop a severe form of the disease with a fatal outcome. Acute Respiratory Distress Syndrome (ARDS) ina pregnant woman can affect the supply of oxygen to the fetus and initiate the mechanism of metabolic disorders of the fetus and newborn caused by asphyxia. The initial metabolic response of the newborn to the lack of oxygen in the tissues is the activation of anaerobic glycolysis in the tissues and an increase in the concentration of lactate and ketones. Lipid peroxidation, especially in nerve cells, is catalyzed by iron released from hemoglobin, transferrin and ferritin, whose release is induced by tissue acidosis and free oxygen radicals. Ferroptosis-inducing factors can directly or indirectly affect glutathione peroxidase through various pathways, resulting in a decrease in the antioxidant capacity and accumulation of lipid reactive oxygen species (ROS) in the cells, ultimately leading to oxidative cell stress, and finally, death. Conclusion: damage to the mitochondria as a result of lipid peroxidation caused by the COVID-19 disease can cause the death of a newborn and pregnant women as well as short time and long-time sequelae.

Skin inflammation and impaired adipogenesis in a mouse model of acid ceramidase deficiency

Acid ceramidase catalyzes the degradation of ceramide into sphingosine and a free fatty acid. Acid ceramidase deficiency results in lipid accumulation in many tissues and leads to the development of Farber disease (FD). Typical manifestations of classical FD include formation of subcutaneous nodules and joint contractures as well as the development of a hoarse voice. Healthy skin depends on a unique lipid profile to form a barrier that confers protection from pathogens, prevents excessive water loss, and mediates cell-cell communication. Ceramides comprise ~50% of total epidermis lipids and regulate cutaneous homeostasis and inflammation. Abnormal skin development including visual skin lesions has been reported in FD patients, but a detailed study of FD skin has not been performed. We conducted a pathophysiological study of the skin in our mouse model of FD. We observed altered lipid composition in FD skin dominated by accumulation of all studied ceramide species and buildup of abnormal storage structures affecting mainly the dermis. A deficiency of acid ceramidase activity also led to the activation of inflammatory IL-6/JAK/signal transducer and activator of transcription 3 and noncanonical NF-κB signaling pathways. Last, we report reduced proliferation of FD mouse fibroblasts and adipose-derived stem/stromal cells (ASC) along with impaired differentiation of ASCs into mature adipocytes.

TBK1-mTOR Signaling Attenuates Obesity-Linked Hyperglycemia and Insulin Resistance

The innate immune kinase TBK1 (TANK-binding kinase 1) responds to microbial-derived signals to initiate responses against viral and bacterial pathogens. More recent work implicates TBK1 in metabolism and tumorigenesis. The kinase mTOR (mechanistic target of rapamycin) integrates diverse environmental cues to control fundamental cellular processes. Our prior work demonstrated in cells that TBK1 phosphorylates mTOR (on S2159) to increase mTORC1 and mTORC2 catalytic activity and signaling. Here we investigate a role for TBK1-mTOR signaling in control of glucose metabolism in vivo. We find that mice with diet-induced obesity (DIO) but not lean mice bearing a whole-body "TBK1-resistant" Mtor S2159A knock-in allele (MtorA/A) display exacerbated hyperglycemia and systemic insulin resistance with no change in energy balance. Mechanistically, Mtor S2159A knock-in in DIO mice reduces mTORC1 and mTORC2 signaling in response to insulin and innate immune agonists, reduces anti-inflammatory gene expression in adipose tissue, and blunts anti-inflammatory macrophage M2 polarization, phenotypes shared by mice with tissue-specific inactivation of TBK1 or mTOR complexes. Tissues from DIO mice display elevated TBK1 activity and mTOR S2159 phosphorylation relative to lean mice. We propose a model whereby obesity-associated signals increase TBK1 activity and mTOR phosphorylation, which boost mTORC1 and mTORC2 signaling in parallel to the insulin pathway, thereby attenuating insulin resistance to improve glycemic control during diet-induced obesity.

Impaired wound healing in diabetes

Impaired wound healing for patients with diabetes is due to a constellation of structural, biochemical, cellular and microbial factors. Hyperglycaemia and its associated inflammation contribute to immune dysfunction, vascular damage, neuropathy, cellular senescence, impaired transition beyond the inflammatory stage, microbiome disruptions, failed extracellular matrix formation, growth factor and cytokine imbalance, limited re-epithelialisation, and alterations in fibroblast migration and proliferation. Optimising glycaemic control remains the primary intervention to prevent continual dysfunction and comorbid disease progression.

Adipose tissue-to-breast cancer crosstalk: Comprehensive insights

The review focuses on mechanistic evidence for the link between obesity and breast cancer. According to the IARC study, there is sufficient evidence that obesity is closely related to a variety of cancers. Among them, breast cancer is particularly disturbed by adipose tissue due to the unique histological structure of the breast. The review introduces the relationship between obesity and breast cancer from two aspects, including factors that promote tumorigenesis or metastasis. We summarize alterations in adipokines and metabolic pathways that contribute to breast cancer development. Breast cancer metastasis is closely related to obesity-induced pro-inflammatory microenvironment, adipose stem cells, and miRNAs. Based on the mechanism by which obesity causes breast cancer, we list possible therapeutic directions, including reducing the risk of breast cancer and inhibiting the progression of breast cancer. We also discussed the risk of autologous breast remodeling and fat transplantation. Finally, the causes of the obesity paradox and the function of enhancing immunity are discussed. Evaluating the balance between obesity-induced inflammation and enhanced immunity warrants further study.

Macrophage Polarization Mediated by Mitochondrial Dysfunction Induces Adipose Tissue Inflammation in Obesity

Obesity is one of the prominent global health issues, contributing to the growing prevalence of insulin resistance and type 2 diabetes. Chronic inflammation in adipose tissue is considered as a key risk factor for the development of insulin resistance and type 2 diabetes in obese individuals. Macrophages are the most abundant immune cells in adipose tissue and play an important role in adipose tissue inflammation. Mitochondria are critical for regulating macrophage polarization, differentiation, and survival. Changes to mitochondrial metabolism and physiology induced by extracellular signals may underlie the corresponding state of macrophage activation. Macrophage mitochondrial dysfunction is a key mediator of obesity-induced macrophage inflammatory response and subsequent systemic insulin resistance. Mitochondrial dysfunction drives the activation of the NLRP3 inflammasome, which induces the release of IL-1β. IL-1β leads to decreased insulin sensitivity of insulin target cells via paracrine signaling or infiltration into the systemic circulation. In this review, we discuss the new findings on how obesity induces macrophage mitochondrial dysfunction and how mitochondrial dysfunction induces NLRP3 inflammasome activation. We also summarize therapeutic approaches targeting mitochondria for the treatment of diabetes.

Biology of macrophage fate decision: Implication in inflammatory disorders

The activation of immune cells in response to stimuli present in their microenvironment is regulated by their metabolic profile. Unlike the signal transduction events, which overlap to a huge degree in diverse cellular processes, the metabolome of a cell reflects a more precise picture of cell physiology and function. Different factors governing the cellular metabolome include receptor signaling, macro and micronutrients, normoxic and hypoxic conditions, energy needs, and biomass demand. Macrophages have enormous plasticity and can perform diverse functions depending upon their phenotypic state. This review presents recent updates on the cellular metabolome and molecular patterns associated with M1 and M2 macrophages, also termed "classically activated macrophages" and "alternatively activated macrophages," respectively. M1 macrophages are proinflammatory in nature and predominantly Th1-specific immune responses induce their polarization. On the contrary, M2 macrophages are anti-inflammatory in nature and primarily participate in Th2-specific responses. Interestingly, the same macrophage cell can adapt to the M1 or M2 phenotype depending upon the clues from its microenvironment. We elaborate on the various tissue niche-specific factors, which govern macrophage metabolism and heterogeneity. Furthermore, the current review provides an in-depth account of deregulated macrophage metabolism associated with pathological disorders such as cancer, obesity, and atherosclerosis. We further highlight significant differences in various metabolic pathways governing the cellular bioenergetics and their impact on macrophage effector functions and associated disorders.

Changes of Th17 cells, regulatory T cells, Treg/Th17, IL-17 and IL-10 in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

PURPOSE

The aim of this study was to investigate the changes of Helper T cells 17 (Th17 cells), Regulatory T cells (Treg cells), Treg/Th17, Interleukin-17 (IL-17) and Interleukin-10 (IL-10) in patients with type 2 diabetes mellitus (T2DM).

METHODS

Four electronic resource databases were searched from their inception to 1 August 2021. Case-control studies about changes of Th17 cells, Treg cells, Treg/Th17, IL-17 and IL-10 in patients with T2DM were retrieved. We performed this meta-analysis via RevMan V.5.3 and Stata14.

RESULTS

20 studies with 1242 individuals were included in the meta-analysis. Compared with the controls, the patients with T2DM had significantly increased levels of percentage of Th17 cells (SMD, 1.74; 95% CI, 0.47-3.01; p < 0.001), IL-17 (SMD, 2.17; 95% CI, 0.06-4.28; p < 0.001), IL-10 (SMD, 1.20; 95% CI, 0.81-1.59; p = 0.003), but decreased levels of percentage of Treg cells (SMD, -1.17; 95% CI, -2.22 to -0.13; p < 0.001) and Treg/Th17 ratio (SMD, -4.43; 95% CI, -7.07 to -1.78; p < 0.001). Subgroup analysis showed that percentage of CD4⁺CD25⁺FOXP3⁺ Tregs (SMD, -2.36; 95% CI, -3.19 to -1.52; p = 0.003) in patients was notably lower than controls. While not significant changes were found in the percentage of CD4⁺CD25⁺Tregs (SMD, 0.03; 95% CI, -0.34-0.40; p = 0.63) between patients and controls. For plasma or serum IL-10, a higher plasma IL-10 level (SMD,1.37; 95% CI, 0.92-1.82; p = 0.01) was observed in T2DM. While serum IL-10 (SMD, 0.73; 95% CI, 0.35-1.12; p = 0.79) had no obvious difference between patients and controls. For ELISA or flow cytometry, IL-10 (SMD, 1.2; 95% CI, 0.71-1.70; p = 0.001) was higher in T2DM patients by using detection method of ELISA. Yet IL-10 using flow cytometry and subgroup analysis of IL-17 had no significant differences.

CONCLUSIONS

Adaptive immune system indeed plays an essential role in the process of T2DM. Imbalance between Th17 and Treg triggers pro-inflammatory environment in patients with T2DM.

NEAT1: A novel long non-coding RNA involved in mediating type 2 diabetes and its various complications

Background:

Nuclear‐enriched abundant transcript 1 (abbreviated as NEAT1) refers to a long-chain non-coding RNA involved within various physiological and pathological processes. This study aimed at clarifying the effect and molecule system of neat1 within nonalcoholic fatty liver disease (NAFLD) as well as type 2 diabetes (T2DM).

Method:

In this review, we summarize and analyze current studies concerning mechanisms of NEAT1 in the development of type 2 diabetes and its complications. Also, we search the papers of NEAT1 in applying to NAFLD. The related studies were obtained through a systematic search of Pubmed.

Results:

Neat1 displays a close correlation with how T2DM occurs and develops, and it was confirmed to be significantly up-regulated in T2DM and its various complications (e.g., diabetics nephropathy, diabetics cardiomyopathy, diabetics retinopathy as well as diabetic neuropathy). Besides, neat1 is capable of impacting the occurrence, development and prognosis of NAFLD and T2DM.

Conclusion:

LncRNA neat1 is likely to act as a novel therapeutic target for and T2DM and its complications. Moreover, nonalcoholic fatty liver disease is also correlated with NEAT1.

Quercetin: an effective polyphenol in alleviating diabetes and diabetic complications

Various studies, especially in recent years, have shown that quercetin has beneficial therapeutic effects in various human diseases, including diabetes. Quercetin has significant anti-diabetic effects and may be helpful in lowering blood sugar and increasing insulin sensitivity. Quercetin appears to affect many factors and signaling pathways involved in insulin resistance and the pathogenesis of type 2 of diabetes. TNFα, NFKB, AMPK, AKT, and NRF2 are among the factors that are affected by quercetin. In addition, quercetin can be effective in preventing and ameliorating the diabetic complications, including diabetic nephropathy, cardiovascular complications, neuropathy, delayed wound healing, and retinopathy, and affects the key mechanisms involved in the pathogenesis of these complications. These positive effects of quercetin may be related to its anti-inflammatory and anti-oxidant properties. In this article, after a brief review of the pathogenesis of insulin resistance and type 2 diabetes, we will review the latest findings on the anti-diabetic effects of quercetin with a molecular perspective. Then we will review the effects of quercetin on the key mechanisms of pathogenesis of diabetes complications including nephropathy, cardiovascular complications, neuropathy, delayed wound healing, and retinopathy. Finally, clinical trials investigating the effect of quercetin on diabetes and diabetes complications will be reviewed.

Obesity and Leptin Resistance in the Regulation of the Type I Interferon Early Response and the Increased Risk for Severe COVID-19

Obesity, and obesity-associated conditions such as hypertension, chronic kidney disease, type 2 diabetes, and cardiovascular disease, are important risk factors for severe Coronavirus disease-2019 (COVID-19). The common denominator is metaflammation, a portmanteau of metabolism and inflammation, which is characterized by chronically elevated levels of leptin and pro-inflammatory cytokines. These induce the “Suppressor Of Cytokine Signaling 1 and 3” (SOCS1/3), which deactivates the leptin receptor and also other SOCS1/3 sensitive cytokine receptors in immune cells, impairing the type I and III interferon early responses. By also upregulating SOCS1/3, Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV)-2 adds a significant boost to this. The ensuing consequence is a delayed but over-reactive immune response, characterized by high-grade inflammation (e.g., cytokine storm), endothelial damage, and hypercoagulation, thus leading to severe COVID-19. Superimposing an acute disturbance, such as a SARS-CoV-2 infection, on metaflammation severely tests resilience. In the long run, metaflammation causes the “typical western” conditions associated with metabolic syndrome. Severe COVID-19 and other serious infectious diseases can be added to the list of its short-term consequences. Therefore, preventive measures should include not only vaccination and the well-established actions intended to avoid infection, but also dietary and lifestyle interventions aimed at improving body composition and preventing or reversing metaflammation.

Extracellular miRNAs as mediators of obesity-associated disease

Extracellular miRNAs are found in a variety of body fluids and mediate intercellular and interorgan communication, thus regulating gene expression and cellular metabolism. These miRNAs are secreted either in small vesicles/exosomes (sEV) or bound to proteins such as Argonaute and high-density lipoprotein. Both exosomal and protein-bound circulating miRNAs are altered in obesity. Although all tissues can contribute to changes in circulating miRNAs, adipose tissue itself is an important source of these miRNAs, especially those in sEVs. These are derived from both adipocytes and macrophages and participate in crosstalk between these cells, as well as peripheral tissues, including liver, skeletal muscle and pancreas, whose function may be impaired in obesity. Changes in levels of circulating miRNAs have also been linked to the beneficial effects induced by weight loss interventions, including diet, exercise and bariatric surgery, further indicating a role for these miRNAs as mediators of disease pathogenesis. Here, we review the role of circulating miRNAs in the pathophysiology of obesity and explore their potential use as biomarkers and in therapy of obesity-associated metabolic syndrome.

Trained immunity: A Yin-Yang balance

Traditionally, immune memory is regarded as an exclusive hallmark of adaptive immunity. However, a growing body of evidence suggesting that innate immune cells show adaptive characteristics has challenged this dogma. In the past decade, trained immunity, a de facto innate immune memory, has been defined as a long-term functional reprogramming of cells of the innate immune system: the reprogramming is evoked by endogenous or exogenous insults, the cells return to a nonactivated state and subsequently show altered inflammatory responses against a second challenge. Trained immunity became regarded as a mechanism selected in evolution to protect against infection; however, a maladaptive effect might result in hyperinflammation. This dual effect is consistent with the Yin-Yang theory in traditional Chinese philosophy, in which Yang represents active, positive, and aggressive factors, whereas Yin represents passive, negative, and inhibitory factors. In this review, we give a brief overview of history and latest progress about trained immunity, including experimental models, inductors, molecular mechanisms, clinical application and so on. Moreover, this is the first time to put forward the theory of Yin-Yang balance to understand trained immunity. We envision that more efforts will be focused on developing novel immunotherapies targeting trained immunity in the coming years.

A Systemic Review of the Integral Role of TRPM2 in Ischemic Stroke: From Upstream Risk Factors to Ultimate Neuronal Death

Ischemic stroke causes a heavy health burden worldwide, with over 10 million new cases every year. Despite the high prevalence and mortality rate of ischemic stroke, the underlying molecular mechanisms for the common etiological factors of ischemic stroke and ischemic stroke itself remain unclear, which results in insufficient preventive strategies and ineffective treatments for this devastating disease. In this review, we demonstrate that transient receptor potential cation channel, subfamily M, member 2 (TRPM2), a non-selective ion channel activated by oxidative stress, is actively involved in all the important steps in the etiology and pathology of ischemic stroke. TRPM2 could be a promising target in screening more effective prophylactic strategies and therapeutic medications for ischemic stroke.

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.

Exploring the common gene signatures and pathogeneses of obesity with Alzheimer's disease via transcriptome data

BACKGROUND

Obesity is a complex condition that influences several organ systems and physiologic systems. Obesity (OB) is closely linked to Alzheimer's disease (AD). However, the interrelationship between them remains unclear. The purpose of this study is to explore the key genes and potential molecular mechanisms in obesity and AD.

METHODS

The microarray data for OB and AD were downloaded from the Gene Expression Omnibus (GEO) database. Weighted gene correlation network analysis (WGCNA) was used to delineate the co-expression modules related to OB and AD. The shared genes existing in obesity and AD were identified through biological process analyses using the DAVID website, which then constructed the Protein-Protein Interaction (PPI) Network and selected the hub genes by Cytoscape. The results were validated in other microarray data by differential gene analysis. Moreover, the hub gene expressions were further determined in mice by qPCR.

RESULTS

The WGCNA identifies five modules and four modules as significant modules with OB and AD, respectively. Functional analysis of shared genes emphasized that inflammation response and mitochondrial functionality were common features in the pathophysiology of OB and AD. The results of differential gene analysis in other microarray data were extremely similar to them. Then six important hub genes were selected and identified using cytoHubba, including MMP9, PECAM1, C3AR1, IL1R1, PPARGC1α, and COQ3. Finally, we validated the hub gene expressions via qPCR.

CONCLUSIONS

Our work revealed the high inflammation/immune response and mitochondrial impairment in OB patients, which might be a crucial susceptibility factor for AD. Meanwhile, we identified novel gene candidates such as MMP9, PECAM1, C3AR1, IL1R1, PPARGC1α, and COQ3 that could be used as biomarkers or potential therapeutic targets for OB with AD.

Association of metabolic syndrome and the risk of bladder cancer: A prospective cohort study

Background

Metabolic syndrome (MetS) and its components have been shown as risk factors for several solid cancers. However, current epidemiological evidence about the relevance of MetS and bladder cancer risk was limited.

Methods

We conducted a prospective cohort study of 476,986 participants with undiagnosed bladder cancer based on the UK Biobank. MetS was defined as the presence of at least three of the five selected indicators: hypertension, central obesity, raised triglyceride, reduced HDL-cholesterol, and raised fasting plasma glucose. Bladder cancer has been identified through contact with the British Cancer Registry (median follow-up time: 6.6 years). We assessed hazard ratio (HR) and 95% confidence interval (CI) through Cox proportional hazard regression after adjusting for demographic and lifestyle factors. Non-linear associations for individual MetS components were assessed by the restricted cubic spline method.

Results

During a follow-up of 3,112,566 person-years, 487 cases of bladder cancer were ascertained. MetS (HR = 1.32, 95% CI = 1.08-1.61), central obesity (HR = 1.39, 95% CI = 1.15-1.68), dyslipidemia for HDL cholesterol (HR = 1.31, 95% CI = 1.04-1.66), and hyperglycemia (HR = 1.44, 95% CI = 1.16-1.79) were associated with elevated risk of bladder cancer. Bladder cancer risk increased with the number of MetS components. In stratified analyses, MetS showed similar effects in bladder cancer independently with sex, age, cigarette and alcohol use, physical activity, and dietary factors. Higher waist circumference, BMI, fasting blood glucose, and glycosylated hemoglobin were independently associated with increased risk of bladder cancer, with no evidence against non-linearity.

Conclusion

MetS might be an independent risk factor for bladder cancer. Our findings highlighted the importance of individualized management of MetS components for preventing bladder cancer.

Current Perspectives on Nonalcoholic Fatty Liver Disease in Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is one of the most common reproductive, endocrine, and metabolic disorders in premenopausal women. Clinically, PCOS is mainly caused by androgen excess and ovarian dysfunction, manifested by anovulatory menstrual cycles, infertility, and hirsutism. In addition, PCOS increases the risk of insulin resistance, obesity, cardiovascular disease, anxiety and depression, dyslipidemia, and endometrial cancer. Nonalcoholic fatty liver disease (NAFLD) is defined as ≥5% fat accumulation in the liver in the absence of remaining secondary causes and has become one of the most common chronic liver diseases worldwide. The prevalence of NAFLD is significantly higher and more severe in women with PCOS, and its pathogenesis can be associated with various risk factors such as hyperandrogenemia, insulin resistance, obesity, chronic low-grade inflammation, and genetic factors. Although there is no definitive solution for the management of NAFLD in PCOS, some progress has been made. Lifestyle modification should be the basis of management, and drugs to improve metabolism, such as insulin sensitizers and glucagon-like peptide-1 agonists, may show better efficacy. Bariatric surgery may also be a treatment of NAFLD in obese women with PCOS. This paper reviews three aspects of prevalence, risk factors, and management, in order to better understand the current state of research on NAFLD in PCOS, to explore the pathogenesis of NAFLD in PCOS, and to encourage further research on the application of drugs in this field.

Network Analyses Reveal Negative Link Between Changes in Adipose Tissue GDF15 and BMI During Dietary-induced Weight Loss

CONTEXT

Adipose tissue (AT) transcriptome studies provide holistic pictures of adaptation to weight and related bioclinical settings changes.

OBJECTIVE

To implement AT gene expression profiling and investigate the link between changes in bioclinical parameters and AT gene expression during 3 steps of a 2-phase dietary intervention (DI).

METHODS

AT transcriptome profiling was obtained from sequencing 1051 samples, corresponding to 556 distinct individuals enrolled in a weight loss intervention (8-week low-calorie diet (LCD) at 800 kcal/day) followed with a 6-month ad libitum randomized DI. Transcriptome profiles obtained with QuantSeq sequencing were benchmarked against Illumina RNAseq. Reverse transcription quantitative polymerase chain reaction was used to further confirm associations. Cell specificity was assessed using freshly isolated cells and THP-1 cell line.

RESULTS

During LCD, 5 modules were found, of which 3 included at least 1 bioclinical variable. Change in body mass index (BMI) connected with changes in mRNA level of genes with inflammatory response signature. In this module, change in BMI was negatively associated with changes in expression of genes encoding secreted protein (GDF15, CCL3, and SPP1). Through all phases of the DI, change in GDF15 was connected to changes in SPP1, CCL3, LIPA and CD68. Further characterization showed that these genes were specific to macrophages (with LIPA, CD68 and GDF15 expressed in anti-inflammatory macrophages) and GDF15 also expressed in preadipocytes.

CONCLUSION

Network analyses identified a novel AT feature with GDF15 upregulated with calorie restriction induced weight loss, concomitantly to macrophage markers. In AT, GDF15 was expressed in preadipocytes and macrophages where it was a hallmark of anti-inflammatory cells.

TNFα Mediates Inflammation-Induced Effects on PPARG Splicing in Adipose Tissue and Mesenchymal Precursor Cells

Low-grade chronic inflammation and reduced differentiation capacity are hallmarks of hypertrophic adipose tissue (AT) and key contributors of insulin resistance. We identified PPARGΔ5 as a dominant-negative splicing isoform overexpressed in the AT of obese/diabetic patients able to impair adipocyte differentiation and PPARγ activity in hypertrophic adipocytes. Herein, we investigate the impact of macrophage-secreted pro-inflammatory factors on PPARG splicing, focusing on PPARGΔ5. We report that the epididymal AT of LPS-treated mice displays increased PpargΔ5/cPparg ratio and reduced expression of Pparg-regulated genes. Interestingly, pro-inflammatory factors secreted from murine and human pro-inflammatory macrophages enhance the PPARGΔ5/cPPARG ratio in exposed adipogenic precursors. TNFα is identified herein as factor able to alter PPARG splicing—increasing PPARGΔ5/cPPARG ratio—through PI3K/Akt signaling and SRp40 splicing factor. In line with in vitro data, TNFA expression is higher in the SAT of obese (vs. lean) patients and positively correlates with PPARGΔ5 levels. In conclusion, our results indicate that inflammatory factors secreted by metabolically-activated macrophages are potent stimuli that modulate the expression and splicing of PPARG. The resulting imbalance between canonical and dominant negative isoforms may crucially contribute to impair PPARγ activity in hypertrophic AT, exacerbating the defective adipogenic capacity of precursor cells.

Expression of the miR-17~92a cluster of microRNAs by regulatory T cells controls blood glucose homeostasis

Regulatory T cells (Tregs) are a specialized immune cell type that play important roles in regulating immune responses. However, those found in adipose tissue, particularly visceral adipose tissue (VAT), have also been shown to exert metabolic regulatory functions. This study investigated the requirement of the miR-17~92a cluster of microRNAs in VAT Tregs and the impact on blood glucose. This cluster of microRNAs is one that we previously showed to be important for the fitness of Tregs found in secondary lymphoid organs. It was found that male mice with Treg-specific miR-17~92a deficiency are resistant to impaired glucose tolerance induced by a high-fat diet. However, high-fat feeding still impaired glucose tolerance in female mice with Treg-specific miR-17~92a deficiency. There was an increase in KLRG1^- naïve Tregs and a loss of KLRG1⁺ terminally differentiated Tregs in the VAT of Treg-specific miR-17~92a-deficient male mice but not in female mice. The protection of male mice from high-fat feeding was also associated with increased interleukin-10 and reduced interferonγ expression by conventional CD4⁺ T cells and reduced interleukin-2 expression by both CD4⁺ and CD8⁺ T cells in the VAT. Together this suggests that expression of miR-17~92a by VAT Tregs regulates the effector phenotype of conventional T cells and in turn the metabolic function of adipose tissue and blood glucose homeostasis.

Potential Applications and Functional Roles of Exosomes in Cardiometabolic Disease

Despite diagnostic and therapeutic advances, cardiometabolic disease remains the leading cause of death worldwide. Extracellular vesicles (EVs), which include exosomes and microvesicles, have gained particular interest because of their role in metabolic homeostasis and cardiovascular physiology. Indeed, EVs are recognized as critical mediators of intercellular communication in the cardiovascular system. Exosomes are naturally occurring nanocarriers that transfer biological information in the setting of metabolic abnormalities and cardiac dysfunction. The study of these EVs can increase our knowledge on the pathophysiological mechanisms of metabolic disorders and their cardiovascular complications. Because of their inherent properties and composition, exosomes have been proposed as diagnostic and prognostic biomarkers and therapeutics for specific targeting and drug delivery. Emerging fields of study explore the use exosomes as tools for gene therapy and as a cell-free alternative for regenerative medicine. Furthermore, innovative biomaterials can incorporate exosomes to enhance tissue regeneration and engineering. In this work, we summarize the most recent knowledge on the role of exosomes in cardiometabolic pathophysiology while highlighting their potential therapeutic applications.

Effects of a pinitol-rich Glycyrrhiza glabra L. leaf extract on insulin and inflammatory signaling pathways in palmitate-induced hypertrophic adipocytes

Glycyrrhiza glabra roots have been well studied for their pharmacological activities, whereas less research has been conducted on liquorice aerial parts. Leaves represent a good source of D-pinitol, useful in the treatment of insulin resistance-related pathologies. Herein, we analyzed the in vitro effects of a D-pinitol-rich methanolic extract from Glycyrrhiza glabra leaves (GGLME) against lipotoxicity-related hypertrophy, inflammation, and insulin resistance in 3T3-L1 adipocytes exposed to palmitic acid (PA), comparing its activity with D-pinitol. GGLME pretreatment decreased lipid deposition, PPAR-γ, and NF-κB pathway induced by PA, similarly to D-pinitol, and improved insulin sensitivity, in presence or not of PA, increasing PI3K, pAkt, and GLUT1 levels. This study confirms that liquorice leaves, considered a waste of resource, could potentially be reused, and support further in vivo studies on animal and human models. In conclusion, liquorice leaves extract represents a potential candidate for prevention of metabolically induced inflammation, frequently leading to metabolic disorders.

From obesity to Alzheimer's disease through insulin resistance

Alzheimer's disease is one of the most frequent forms of dementia. It is a progressive neurodegenerative disease, characterized by presence of amyloid plaques and neurofibrillary tangles in the brain. Obesity is regarded as abnormal fat accumulation with deleterious impact on human health. There is full scientific evidence that obesity and the metabolic comorbidities (e.g., insulin resistance, hyperglycaemia, and type 2 diabetes) are related to Alzheimer's disease and likely in the causative pathway. Numerous studies have identified several overlapping neurodegenerative mechanisms, including oxidative stress, mitochondrial dysfunction, and inflammation. In this review, we present how obesity and the associated lipotoxicity as well as chronic inflammation initiate a state of insulin resistance that in turn, may have a role in causing the characteristic cerebral alterations of AD. In particular, we focus on the molecular mechanisms linking the obesity-induced impairment in insulin signalling to the upregulation of Aβ aggregation, tau hyper-phosphorylation, inflammation, oxidative stress and mitochondrial dysfunction.

Association of measures of body fat with serum alpha-tocopherol and its metabolites in middle-aged individuals

BACKGROUND AND AIMS

The accumulation of fat increases the formation of lipid peroxides, which are partly scavenged by alpha-tocopherol (α-TOH). Here, we aimed to investigate the associations between different measures of (abdominal) fat and levels of urinary α-TOH metabolites in middle-aged individuals.

METHODS AND RESULTS

In this cross-sectional analysis in the Netherlands Epidemiology of Obesity study (N = 511, 53% women; mean [SD] age of 55 [6.1] years), serum α-TOH and α-TOH metabolites from 24-h urine were measured as alpha-tocopheronolactone hydroquinone (α-TLHQ, oxidized) and alpha-carboxymethyl-hydroxychroman (α-CEHC, enzymatically converted) using liquid-chromatography-tandem mass spectrometry. Body mass index and total body fat were measured, and abdominal subcutaneous and visceral adipose tissue (aSAT and VAT) were assessed using magnetic resonance imaging. Using multivariable-adjusted linear regression analyses, we analysed the associations of BMI, TBF, aSAT and VAT with levels of urinary α-TOH metabolites, adjusted for confounders. We observed no evidence for associations between body fat measures and serum α-TOH. Higher BMI and TBF were associated with lower urinary levels of TLHQ (0.95 [95%CI: 0.90, 1.00] and 0.94 [0.88, 1.01] times per SD, respectively) and with lower TLHQ relative to CEHC (0.93 [0.90, 0.98] and 0.93 [0.87, 0.98] times per SD, respectively). We observed similar associations for VAT (TLHQ: 0.94 [0.89, 0.99] times per SD), but not for aSAT.

CONCLUSIONS

Opposite to our research hypothesis, higher abdominal adiposity was moderately associated with lower levels of oxidized α-TOH metabolites, which might reflect lower vitamin E antioxidative activity in individuals with higher abdominal fat instead.

Modulation of TRIB3 and Macrophage Phenotype to Attenuate Insulin Resistance After Downhill Running in Mice

Eccentric exercise training accompanied by a low-fat diet can prevent insulin resistance (IR) and is currently an effective method for the treatment of IR induced by high-fat diet (HFD)-associated obesity. However, the molecular mechanisms underlying this improvement of IR in adipose tissue are still not completely clear. In this study, 5–6-week-old male mice were randomly divided into a standard control diet (SCD) group (SC, n = 12) and a HFD group (HF, n = 72). After 12 weeks, 12 mice in each group were randomly sacrificed. The remaining mice in the HF group were randomly submitted to one of the following experimental protocols for 8 weeks: obesity-HFD-sedentary (OHF-Sed, n = 14), obesity-HFD-exercise (OHF-Ex, n = 16), obesity-SCD-sedentary (OSC-Sed, n = 14), and obesity-SCD-exercise (OSC-Ex, n = 16). All obese mice in the exercise group were subjected to downhill running. Half of the mice in each group received an insulin injection (0.75 U/kg) before sample collection. Epididymal fat was removed and weighed. Adipocyte size and inflammatory cell infiltration were observed by H&E staining. Both basal and insulin-stimulated GLUT4 fluorescence and protein contents were detected by immunofluorescence and Western blot. Levels of IL-1β and IL-10 were detected by ELISA. Protein contents of iNOS, Arg-1, TRIB3, p-AKT, and AKT were determined by Western blot. CD86 and CD206 fluorescence were determined by immunofluorescence. The results showed that a HFD for 12 weeks induced IR accompanied by adipose tissue macrophages M1 polarization (increased iNOS protein content and CD86 fluorescence) and TRIB3-AKT activation. Downhill running accompanied by a low-fat diet attenuated IR (p < 0.01), reduced inflammation levels (increased IL-10 protein content and decreased IL-1β protein content), inhibited adipose tissue macrophages M1 polarization (decreased iNOS protein content and CD86 fluorescence) and promoted M2 polarization (increased Arg-1 protein content and CD206 fluorescence), and suppressed TRIB3-AKT signaling. We concluded that downhill running accompanied by dietary fat regulation attenuates HFD-related IR in mice, which may be associated with reduced TRIB3-AKT signaling and activated M2 macrophages in adipose tissue.