Obesity-associated Metabolic Disorders Research Articles

Role of FKBP51 on the development of obesity-associated metabolic disorders

Role of FKBP51 on the development of obesity-associated metabolic disorders

Deciphering the Potential Role of Specialized Pro-Resolving Mediators in Obesity-Associated Metabolic Disorders.

Obesity-related metabolic disorders, including diabetes, non-alcoholic fatty liver disease (NAFLD), and cardiovascular disease, increasingly threaten global health. Uncontrolled inflammation is a key pathophysiological factor in many of these conditions. In the human body, inflammatory responses generate specialized pro-resolving mediators (SPMs), which are crucial for resolving inflammation and restoring tissue balance. SPMs derived from omega-3 polyunsaturated fatty acids (n-3 PUFAs) such as resolvins, protectins, and maresins hold promise in attenuating the chronic inflammatory diseases associated with lipid metabolism disorders. Recent research has highlighted the therapeutic potential of n-3 PUFA-derived metabolites in addressing these metabolic disorders. However, the understanding of the pharmacological aspects of SPMs, particularly in obesity-related metabolic disorders, remains limited. This review comprehensively summarizes recent advances in understanding the role of SPMs in resolving metabolic disorders, based on studies in animal models and humans. These studies indicate that SPMs have potential as therapeutic targets for combating obesity, as well as offering insights into their mechanisms of action.

Jaboticaba (Plinia jaboticaba (Vell.) Berg) polyphenols alleviate skeletal muscle insulin resistance by modulating PI3K/Akt/GLUT-4 and AMPK signaling pathways in diet-induced obese mice

Skeletal muscle responds for most of the insulin-stimulated glucose disposal at postprandial state, impacting glucose homeostasis. Polyphenols were shown to prevent obesity-associated glucose intolerance and peripheral insulin resistance in animal models, but the implication of skeletal muscle to these effects is unclear. We investigated the role of polyphenolic extracts from jaboticaba (Plinia jaboticaba (Vell.) Berg) (PEJ), a Brazilian native species, on skeletal muscle insulin resistance in diet-induced obese mice. PEJ administration was associated with an increase in skeletal muscle protein content of glucose transporter-4 (GLUT-4) and AMP-activated protein kinase (AMPK) phosphorylated at Thr172. PEJ also reduced skeletal muscle mRNA levels of inflammatory genes nuclear factor-ҡB (NF-κB), tumoral necrose factor-α (TNF-α), interleukin 1β (IL-1β), and c-Jun N-terminal kinase (JNK). This study demonstrates that polyphenols from jaboticaba may be a valuable therapeutic agent in the management and prevention of obesity-associated metabolic disorders by reducing skeletal muscle obesity-associated insulin resistance and inflammation.Graphical

Pro- and anti-inflammatory cytokines are the game-changers in childhood obesity-associated metabolic disorders (diabetes and non-alcoholic fatty liver diseases).

Childhood obesity is a chronic inflammatory epidemic that affects children worldwide. Obesity affects approximately 1 in 5 children worldwide. Obesity in children can worsen weight gain and raise the risk of obesity-related comorbidities like diabetes and non-alcoholic fatty liver disease (NAFLD). It can also negatively impact the quality of life for these children. Obesity disrupts immune system function, influencing cytokine (interleukins) balance and expression levels, adipokines, and innate and adaptive immune cells. The altered expression of immune system mediators, including interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-17 (IL-17), interleukin-18 (IL-18), transforming growth factor (TGF), tumor necrosis factor (TNF), and others, caused inflammation, progression, and the development of pediatric obesity and linked illnesses such as diabetes and NAFLD. Furthermore, anti-inflammatory cytokines, including interleukin-2 (IL-2), have been shown to have anti-diabetes and IL-1 receptor antagonist (IL-1Ra) anti-diabetic and pro-NAFLFD properties, and interleukin-10 (IL-10) has been shown to have a dual role in managing diabetes and anti-NAFLD. In light of the substantial increase in childhood obesity-associated disorders such as diabetes and NAFLD and the absence of an effective pharmaceutical intervention to inhibit immune modulation factors, it is critical to consider the alteration of immune system components as a preventive and therapeutic approach. Thus, the current review focuses on the most recent information regarding the influence of pro- and anti-inflammatory cytokines (interleukins) and their molecular mechanisms on pediatric obesity-associated disorders (diabetes and NAFLD). Furthermore, we discussed the current therapeutic clinical trials in childhood obesity-associated diseases, diabetes, and NAFLD.

Manipulation of feeding patterns in high fat diet fed rats improves microbiota composition dynamics, inflammation and gut-brain signaling

Chronic consumption of high fat (HF) diets has been shown to increase meal size and meal frequency in rodents, resulting in overeating. Reducing meal frequency and establishing periods of fasting, independently of caloric intake, may improve obesity-associated metabolic disorders. Additionally, diet-driven changes in microbiota composition have been shown to play a critical role in the development and maintenance of metabolic disorders. In this study, we used a pair-feeding paradigm to reduce meal frequency and snacking episodes while maintaining overall intake and body weight in HF fed rats. We hypothesized that manipulation of feeding patterns would improve microbiota composition and metabolic outcomes. Male Wistar rats were placed in three groups consuming either a HF, low fat diet (LF, matched for sugar), or pair-fed HF diet for 7 weeks (n = 11–12/group). Pair-fed animals received the same amount of food consumed by the HF fed group once daily before dark onset (HF-PF). Rats underwent oral glucose tolerance and gut peptide cholecystokinin sensitivity tests. Bacterial DNA was extracted from the feces collected during both dark and light cycles and sequenced via Illumina MiSeq sequencing of the 16S V4 region. Our pair-feeding paradigm reduced meal numbers, especially small meals in the inactive phase, without changing total caloric intake. This shift in feeding patterns reduced relative abundances of obesity-associated bacteria and maintained circadian fluctuations in microbial abundances. These changes were associated with improved gastrointestinal (GI) function, reduced inflammation, and improved glucose tolerance and gut to brain signaling. We concluded from these data that targeting snacking may help improve metabolic outcomes, independently of energy content of the diet and hyperphagia.

Fecal Microbiota Transplantation from Methionine-Restricted Diet Mouse Donors Reduces Fat Deposition in Obese Mice by Remodeling the Gut Microbiota

A methionine-restricted diet (MRD) has been shown to reduce body fat deposition and improve obesity-associated metabolic disorders, with emerging evidence implicating the gut microbiota in mediating these effects. This study investigated the effects and underlying mechanisms of fecal microbiota transplantation (FMT) from MRD mouse donors on body fat deposition in obese mice. Five-week-old male C57BL/6J mice were continuously fed a high-fat diet (HFD, 0.86% methionine + 24% fat) to induce obesity, and then randomly divided into three groups. These groups received FMT from 23-week-old male C57BL/6J mice donors continuously fed with normal diet (0.86% methionine + 4.2% fat), HFD, or MRD (0.17% methionine + 24% fat) for eight weeks, respectively. Our results indicate that FMT from MRD mouse donors reduced body weight, plasma lipid levels, and percentage fat mass. Moreover, FMT from MRD mouse donors elevated the abundance of short-chain fatty acid (SCFA)-producing bacteria while decreasing pro-inflammatory bacteria levels in cecal contents. In addition, systemic metabolic processes were altered, featuring heightened SCFA production and enhanced energy metabolism. FMT from MRD mouse donors further facilitated fat catabolism, inhibited fat anabolism, and decreased lipid levels and lipid accumulation in liver. Meanwhile, FMT from MRD mouse donors also promoted fat browning, decreased adipocyte volume, and reduced fat deposition in adipose tissues. These findings underscore the potential of FMT from MRD mouse donors to improve the gut microbiota and reduce body fat deposition in obese mice. Importantly, our results elucidate that MRD intervention in obesity is, in part, mediated by regulating intestinal microbial composition.

Liver ACOX1 regulates levels of circulating lipids that promote metabolic health through adipose remodeling.

The liver gene expression of the peroxisomal β-oxidation enzyme acyl-coenzyme A oxidase 1 (ACOX1), which catabolizes very long chain fatty acids (VLCFA), increases in the context of obesity, but how this pathway impacts systemic energy metabolism remains unknown. Here, we show that hepatic ACOX1-mediated β-oxidation regulates inter-organ communication involved in metabolic homeostasis. Liver-specific knockout of Acox1 (Acox1-LKO) protects mice from diet-induced obesity, adipose tissue inflammation, and systemic insulin resistance. Serum from Acox1-LKO mice promotes browning in cultured white adipocytes. Global serum lipidomics show increased circulating levels of several species of ω-3 VLCFAs (C24-C28) with previously uncharacterized physiological role that promote browning, mitochondrial biogenesis and Glut4 translocation through activation of the lipid sensor GPR120 in adipocytes. This work identifies hepatic peroxisomal β-oxidation as an important regulator of metabolic homeostasis and suggests that manipulation of ACOX1 or its substrates may treat obesity-associated metabolic disorders.

Adipose tissue macrophage–derived microRNA-210-3p disrupts systemic insulin sensitivity by silencing GLUT4 in obesity

Management of chronic obesity-associated metabolic disorders is a key challenge for biomedical researchers. During chronic obesity, visceral adipose tissue (VAT) undergoes substantial transformation characterized by a unique lipid-rich hypoxic AT microenvironment (ATenv) which plays a crucial role in VAT dysfunction, leading to insulin resistance (IR) and type 2 diabetes(T2D). Here, we demonstrate that obese ATenv triggers the release of miR-210-3p microRNA-loaded extracellular vesicles (EVs) from adipose tissue macrophages (ATMs), which disseminate miR-210-3p to neighboring adipocytes, skeletal muscle cells, and hepatocytes through paracrine and endocrine actions, thereby influencing insulin sensitivity. Moreover, EVs collected from Dicer-silenced miR-210-3p-overexpressed bone marrow-derived macrophages (BMDMs), induce glucose intolerance and IR in lean mice. Mechanistically, miR-210-3p interacts with the 3′-UTR of GLUT4 mRNA and silences its expression, compromising cellular glucose uptake and insulin sensitivity. Therapeutic inhibition of miR-210-3p in VAT notably rescues high-fat diet (HFD)-fed mice from obesity-induced systemic glucose intolerance. Thus, targeting ATM-specific miR-210-3p during obesity could be a promising strategy for managing IR and T2D.

Role of liver FGF21-KLB signaling in ketogenic diet-induced amelioration of hepatic steatosis

BackgroundThe effectiveness of ketogenic diet (KD) in ameliorating fatty liver has been established, although its mechanism is under investigation. Fibroblast growth factor 21 (FGF21) positively regulates obesity-associated metabolic disorders and is elevated by KD. FGF21 conventionally initiates its intracellular signaling via receptor β-klotho (KLB). However, the mechanistic role of FGF21-KLB signaling for KD-ameliorated fatty liver remains unknown. This study aimed to delineate the critical role of FGF21 signaling in the ameliorative effects of KD on hepatic steatosis.MethodsEight-week-old C57BL/6 J mice were fed a chow diet (CD), a high-fat diet (HFD), or a KD for 16 weeks. Adeno-associated virus-mediated liver-specific KLB knockdown mice and control mice were fed a KD for 16 weeks. Phenotypic assessments were conducted during and after the intervention. We investigated the mechanism underlying KD-alleviated hepatic steatosis using multi-omics and validated the expression of key genes.ResultsKD improved hepatic steatosis by upregulating fatty acid oxidation and downregulating lipogenesis. Transcriptional analysis revealed that KD dramatically activated FGF21 pathway, including KLB and fibroblast growth factor receptor 1 (FGFR1). Impairing liver FGF21 signaling via KLB knockdown diminished the beneficial effects of KD on ameliorating fatty liver, insulin resistance, and regulating lipid metabolism.ConclusionKD demonstrates beneficial effects on diet-induced metabolic disorders, particularly on hepatic steatosis. Liver FGF21-KLB signaling plays a critical role in the KD-induced amelioration of hepatic steatosis.

Effect of Indian gooseberry extract on improving methylglyoxal-associated leptin resistance in peripheral tissues of high-fat diet-fed rats.

Increased leptin resistance and methylglyoxal (MG) levels are observed in obese patients. However, whether MG deposits contribute to leptin resistance, oxidative stress, and inflammation in peripheral tissues remains unclear. In addition, the edible fruit of Indian gooseberry (Phyllanthus emblica L.) contains abundant bioactive components such as vitamin C, β-glucogallin (β-glu), gallic acid (GA), and ellagic acid (EA). Water extract of Indian gooseberry fruit (WEIG) and GA has been shown to improve cognitive decline by suppressing brain MG-induced insulin resistance in rats administered a high-fat diet (HFD). Accordingly, this study investigated the functions of WEIG and GA in inhibiting MG-induced leptin resistance, oxidative stress, and inflammation in the peripheral tissues of HFD-fed rats. The results showed that MG, advanced glycation end products (AGEs), and leptin resistance accumulation in the liver, kidney, and perinephric fat were effectively restored by elevated glyoxalase-1 (Glo-1) activity after WEIG and GA administration comparable to that of alagebrium chloride (positive control) treatment in HFD-fed rats. Furthermore, WEIG and GA supplementation increased adiponectin and antioxidant enzymes (glutathione peroxidase, superoxide dismutase, catalase) and decreased inflammatory cytokines (IL-6, IL-1β, TNF-α) in the peripheral tissues of HFD-fed rats. In conclusion, these findings demonstrated that MG may trigger leptin resistance, oxidative stress, and inflammation in peripheral tissues, which could be abolished by WEIG and GA treatment. These results show the potential of P. emblica for functional food development and improving obesity-associated metabolic disorders.

Role of Nutraceuticals in Obesity Management: A Mechanism and Prospective Supported by Molecular Docking Studies.

Obesity and its comorbidities represent a major health problem worldwide. Treatment by reducing food intake and physical activity interventions has limited success especially with elderly people with chronic diseases. Nutraceuticals are naturally originated and successfully used for their physiological and nutritional benefit in health care. They might be alternative means to help lose weight and reduce obesity-associated metabolic disorders with the improvement of health, delay the aging process, prevention of chronic diseases, increase of life expectancy, or support to the structure or function of the body. The current study enumerates the inherent role of nutraceuticals in the management of obesity and its related comorbidities. The study is supported with the molecular docking studies discussing the mechanism of action. An attempt to optimize the role of nutraceuticals is made in this article in addition to widen the scope of its use in this chronic worldwide disease.

Marine fungus Aspergillus c1. sp metabolite activates the HSF1/PGC-1α axis, inducing a thermogenic program for treating obesity

Background and aims: Obesity is one of the most prevalent diseases worldwide with less ideal approved agents in clinic. Activating the HSF1/PGC-1α axis in adipose tissues has been reported to induce thermogenesis in mice, which presents a promising therapeutic avenue for obesity treatment. The present study aimed to identified novel natural HSF1 activator and evaluated the therapeutic effects of the newly discovered compound on obesity-associated metabolic disorders and the molecular mechanisms of these effects.Methods: Our previous reported HSF1/PGC-1α activator screening system was used to identify novel natural HSF1 activator. The PGC-1α luciferase activity, immunoblot, protein nuclear-translocation, immunofluorescence, chromatin immunoprecipitation assays were used to evaluate the activity of compound HN-001 in activating HSF1. The experiments of mitochondrial number measurement, TG assay and imaging, cellular metabolic assay, gene assays, and CRISPR/Cas 9 were applied for investigating the metabolic effect of HN-001 in C3H10-T1/2 adipocytes. The in vivo anti-obesity efficacies and beneficial metabolic effects of HN-001 were evaluated by performing body and fat mass quantification, plasma chemical analysis, GTT, ITT, cold tolerance test, thermogenesis analysis.Results: HN-001 dose- and time-dependently activated HSF1 and induced HSF1 nuclear translocation, resulting in an enhancement in binding with the gene Pgc-1α. This improvement induced activation of adipose thermogenesis and enhancement of mitochondrial oxidation capacity, thus inhibiting adipocyte maturation. Deletion of HSF1 in adipocytes impaired mitochondrial oxidation and abolished the above beneficial metabolic effects of HN-001, including adipocyte browning induction, improvements in mitogenesis and oxidation capacity, and lipid-lowering ability. In mice, HN-001 treatment efficiently alleviated diet-induced obesity and metabolic disorders. These changes were associated with increased body temperature in mice and activation of the HSF1/PGC-1α axis in adipose tissues. UCP1 expression and mitochondrial biogenesis were increased in both white and brown adipose tissues of HN-001-treated mice.Conclusion: These data indicate that HN-001 may have therapeutic potential for obesity-related metabolic diseases by increasing the capacity of energy expenditure in adipose tissues through a mechanism involving the HSF1/PGC-1α axis, which shed new light on the development of novel anti-obesity agents derived from marine sources.

Lactobacillus acidophilus JYLA-126 Ameliorates Obesity-Associated Metabolic Disorders by Positively Regulating the AMPK Signaling Pathway Through the Gut-Liver Axis.

Obesity is a chronic metabolic disease worldwide and is considered a major health problem in contemporary society. Lactobacillus acidophilus have demonstrated beneficial effects on obesity, but the specific mechanism of how it exerts beneficial effects has not been elucidated. Here, we found that L. acidophilus JYLA-126 had good biological properties for intestinal health, such as antioxidation, acid tolerance, bile salt tolerance, antimicrobial activity, and gut colonization. We further identified that supplementation of L. acidophilus JYLA-126 obese mice possessed a dose-dependent amelioration of body weight, intestinal imbalance, and metabolic disorders compared to HFD-induced mice. Mechanistically, the excellent slimming effect of L. acidophilus JYLA-126 was achieved mainly by reversing HFD-induced gut dysbiosis, inhibiting inflammatory factors and balancing the homeostasis of the gut-liver axis. Specifically, L. acidophilus JYLA-126 improved hepatic glycogen synthesis, lowered oxidative stress, and facilitated lipid metabolism by regulating AMPK signaling pathway-related protein expression to restore the overall metabolic level. Accordingly, L. acidophilus JYLA-126 promoted energy uptake efficiency in obese mice, resulting in significant expression of uncoupling protein 1 (UCP1) protein in brown adipose tissue (BAT), and markedly reduced the size of adipocytes. These findings indicate that the anti-obesity activity of L. acidophilus JYLA-126 correlates with activation of the AMPK signaling pathway through improved gut-liver interactions.

Thrombospondin1 antagonist peptide treatment attenuates obesity-associated chronic inflammation and metabolic disorders in a diet-induced obese mouse model

Thrombospondin1 (TSP1) is a multifunctional matricellular protein. Previously, we demonstrated that TSP1 plays a pivotal role in obesity-related inflammation and insulin resistance (IR) by modulating macrophage accumulation and activation in adipose tissue. Moreover, in our in vitro studies, a CD36-derived peptide, functioning as a TSP1 antagonist, effectively inhibited TSP1-induced proinflammatory macrophage activation. However, whether this CD36 peptide can inhibit obesity-induced inflammation and IR in vivo is unknown and determined in this study in a high fat diet-induced obese mouse model (DIO). CD36 peptide or control peptide was intraperitoneally administered into the established obese mice triweekly for 6 weeks. We found that CD36 peptide treatment didn’t affect obesity or weight gain but significantly reduced proinflammatory cytokine production systemically and in visceral fat tissue. Adipose tissue exhibited fewer crown-like structures and reduced macrophage infiltration. CD36 peptide treatment also attenuated the proinflammatory phenotype of bone marrow derived macrophages from obese mice. Furthermore, CD36 peptide treatment improved glucose tolerance and insulin sensitivity, and mitigated obesity-related fatty liver disease and kidney damage. Collectively, this study suggests that the CD36 peptide, as a TSP1 antagonist, shows promise as a novel therapeutic approach for managing obesity-related metabolic disorders.

Correlation analysis of obesity phenotypes with leptin and adiponectin

Obesity can be categorized as metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO). However, individuals with MHO are characterized by the absence of metabolic syndrome (MS) and appear to have lower inflammation levels compared to MUO. This study aimed to investigate the association of obesity phenotypes with leptin (LEP) and adiponectin (ADP). According to the inclusion and exclusion criteria, we selected 178 subjects from the previous cross-sectional survey. Based on the body mass index (BMI) and diagnostic criteria of MS, we divided the individuals into three groups, including healthy control group (HC group), metabolically healthy obesity group (MHO group) and metabolically unhealthy obesity group (MUO group). The concentrations of LEP and ADP in serum were measured, and the association of these two cytokines with different obesity phenotypes were subsequently analyzed. Compared to both the HC and MHO groups, the MUO group showed significantly higher BMI, waist circumference (WC), waist-hip ratio (WHR), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), fasting plasma glucose (FPG), homeostasis model assessment of insulin resistance (Homa-IR) and blood pressure (P < 0.05). In contrast, serum high-density lipoprotein cholesterol (HDL-C) was notably lower in the MUO group (P < 0.05). ADP was found to have a positive correlation with systolic blood pressure (SBP) and a negative correlation with FPG in the MHO group. In the MUO group, LEP demonstrated a positive correlation with fasting insulin (FINS) and Homa-IR, while ADP showed a positive correlation with TC and SBP. Linear regression analysis further indicated that SBP (β = 0.234, P = 0.043), TG (β = − 0.292, P = 0.001) and LDL-C (β = 0.626, P = 0.000) were independently correlated with ADP, and BMI (β = 0.398, P = 0.002) was independently correlated with LEP in obese individuals. In conclusion, ADP and LEP were closely related with glucose and lipid metabolism in obese individuals, these two cytokines might play critical roles in obesity-associated metabolic disorders.

Skeletal muscles and gut microbiota-derived metabolites: novel modulators of adipocyte thermogenesis.

Obesity occurs when overall energy intake surpasses energy expenditure. White adipose tissue is an energy storage site, whereas brown and beige adipose tissues catabolize stored energy to generate heat, which protects against obesity and obesity-associated metabolic disorders. Metabolites are substrates in metabolic reactions that act as signaling molecules, mediating communication between metabolic sites (i.e., adipose tissue, skeletal muscle, and gut microbiota). Although the effects of metabolites from peripheral organs on adipose tissue have been extensively studied, their role in regulating adipocyte thermogenesis requires further investigation. Skeletal muscles and intestinal microorganisms are important metabolic sites in the body, and their metabolites play an important role in obesity. In this review, we consolidated the latest research on skeletal muscles and gut microbiota-derived metabolites that potentially promote adipocyte thermogenesis. Skeletal muscles can release lactate, kynurenic acid, inosine, and β-aminoisobutyric acid, whereas the gut secretes bile acids, butyrate, succinate, cinnabarinic acid, urolithin A, and asparagine. These metabolites function as signaling molecules by interacting with membrane receptors or controlling intracellular enzyme activity. The mechanisms underlying the reciprocal exchange of metabolites between the adipose tissue and other metabolic organs will be a focal point in future studies on obesity. Furthermore, understanding how metabolites regulate adipocyte thermogenesis will provide a basis for establishing new therapeutic targets for obesity.

Deletion of complement factor 5 amplifies glucose intolerance in obese male but not female mice.

Complement factor 5 of the innate immune system generates C5a and C5b ligands, which initiate inflammatory and cell lysis events, respectively. C5 activation has been linked with obesity-associated metabolic disorders; however, whether it has a causative role is unclear. We generated a C5 null (C5-/-) mouse using CRISPR-Cas9 gene editing to determine whether loss of C5 improves obesity-linked metabolic dysfunction. Generation of a new mouse model was prompted in part by the observation of off-target gene mutations in commercially available C5-/- lines. Male and female wild-type (WT), heterozygous (Het), and C5-/- mice were fed low-fat diet (LFD) or high-fat diet (HFD) for 22 wk. Body weight gain did not differ between genotypes on LFD or HFD. In lean animals, male C5-/- mice had similar glucose tolerance compared with WT controls; however, in obese conditions, glucose tolerance was worsened in C5-/- compared with controls. In contrast, female mice did not exhibit differences in glucose tolerance between genotypes under either dietary paradigm. Fasting insulin was not different between genotypes, whereas diet-induced obese male C5-/- mice had lower fed insulin concentrations compared with WT controls. No differences in adipose tissue inflammation or adipocyte size were identified between groups. Similarly, susceptibility to fatty liver and hepatic inflammation was similar between WT and C5-/- mice. However, the systemic cytokine response to acute endotoxin exposure was decreased in C5-/- mice. Together, these data suggest that loss of C5 worsens glucose tolerance in obese male but not female mice. Additional work is required to pinpoint the mechanisms by which loss of C5 amplifies glucose intolerance in obesity.NEW & NOTEWORTHY We generated a new mouse model of complement factor 5 deficiency. This work was prompted by a need for improved transgenic mouse lines of C5, due to off-target gene mutations. We find that loss of C5 worsens glucose tolerance in a sex-dependent manner. Though the mechanisms evoking glucose intolerance are not clear, we are confident this model will be useful in interrogating complement activation in obesity-associated diseases.

Potential role of serum Neutrophil gelatinase-associated lipocalin and legume-based dietary therapy in alleviation of obesity-associated metabolic and renal disorders.

Potential role of serum Neutrophil gelatinase-associated lipocalin and legume-based dietary therapy in alleviation of obesity-associated metabolic and renal disorders.

NGR4 and ERBB4 as Promising Diagnostic and Therapeutic Targets for Metabolic Disorders.

Obese individuals are at high risk for developing type 2 diabetes mellitus, cardiovascular diseases, and nonalcoholic fatty liver disease. The aim of this review was to analyze the scientific literature and databases to reveal the fundamental role of neuregulin 4 (NRG4) and its receptors in the development of obesity-associated metabolic disorders. This review demonstrates that NRG4 and its receptors are promising therapeutic targets for the treatment of socially significant obesity-associated pathologies. The review contains nine chapters. Information on the structure of ERBB4 and NRG4 splice isoforms and subsequent activation of downstream targets is presented. The tissue-specific features of the NRG4 and ERBB4 genes and protein production are also highlighted. The role of NRG4 and ERBB3/4 in the pathophysiological mechanisms of the development of metabolic disorders in obesity is discussed in detail. The final chapter of the review is devoted to the miRNA-dependent regulation of NRG4 and ERBB4. Recent studies have shown that several miRNAs regulate ERBB4 expression, but no information was found on the interaction of NRG4 with miRNAs. We now demonstrate the putative relationships between NRG4 and let-7a-5p, let-7c-5p, miR-423-5p, miR-93-5p, miR-23a-3p, and miR-15b-5p for the first time. In addition, we found SNP mutations affecting the interaction of NRG4 and ERBB4 with miRNA in these genes as well as in miRNAs. In summary, this review provides a detailed and comprehensive overview of the role of NRG4 in obesity-associated metabolic disorders. The review summarizes all current studies on this topic and opens perspectives for future research.

Adipocyte-Derived PXR Signaling Is Dispensable for Diet-Induced Obesity and Metabolic Disorders in Mice.

Pregnane X receptor (PXR) is a xenobiotic receptor that can be activated by numerous chemicals including endogenous hormones, dietary steroids, pharmaceutical agents, and environmental chemicals. PXR has been established to function as a xenobiotic sensor to coordinately regulate xenobiotic metabolism by regulating the expression of many enzymes and transporters required for xenobiotic metabolism. Recent studies have implicated a potentially important role for PXR in obesity and metabolic disease beyond xenobiotic metabolism, but how PXR action in different tissues or cell types contributes to obesity and metabolic disorders remains elusive. To investigate the role of adipocyte PXR in obesity, we generated a novel adipocyte-specific PXR deficient mouse model (PXRΔAd). Notably, we found that loss of adipocyte PXR did not affect food intake, energy expenditure, and obesity in high-fat diet-fed male mice. PXRΔAd mice also had similar obesity-associated metabolic disorders including insulin resistance and hepatic steatosis as control littermates. PXR deficiency in adipocytes did not affect expression of key adipose genes in PXRΔAd mice. Our findings suggest that adipocyte PXR signaling may be dispensable in diet-induced obesity and metabolic disorders in mice. Further studies are needed to understand the role of PXR signaling in obesity and metabolic disorders in the future. SIGNIFICANCE STATEMENT: The authors demonstrate that deficiency of adipocyte pregnane X receptor (PXR) does not affect diet-induced obesity or metabolic disorders in mice and infers that adipocyte PXR signaling may not play a key role in diet-induced obesity. More studies are needed to understand the tissue-specific role of PXR in obesity.