Endocrine functions of adipose tissue

FAM19A5 in vascular aging and osteoporosis: Mechanisms and the "calcification paradox"

Aging induces a progressive decline in the vasculature's structure and function. Vascular aging is a determinant factor for vascular ailments in the elderly. FAM19A5, a recently identified adipokine, has demonstrated involvement in multiple vascular aging-related pathologies, including atherosclerosis, cardio-cerebral vascular diseases and cognitive deficits. This review summarizes the current understanding of FAM19A5' role and explores its putative regulatory mechanisms in various aging-related disorders, including cardiovascular diseases (CVDs), metabolic diseases, neurodegenerative diseases and malignancies. Importantly, we provide novel insights into the underlying therapeutic value of FAM19A5 in osteoporosis. Finally, we outline future perspectives on the diagnostic and therapeutic potential of FAM19A5 in vascular aging-related diseases.

Targeting the GLP-2 receptor in the management of obesity

Recent advancements in understanding glucagon-like peptide 2 (GLP-2) biology and pharmacology have sparked interest in targeting the GLP-2 receptor (GLP-2R) in the treatment of obesity. GLP-2 is a proglucagon-derived 33-amino acid peptide co-secreted from enteroendocrine L cells along with glucagon-like peptide 1 (GLP-1) and has a range of actions via the GLP-2R, which is particularly expressed in the gastrointestinal tract, the liver, adipose tissue, and the central nervous system (CNS). In humans, GLP-2 evidently induces intestinotrophic effects (i.e., induction of intestinal mucosal proliferation and improved gut barrier function) and promotes mesenteric blood flow. However, GLP-2 does not seem to have appetite or food intake-reducing effects in humans, but its gut barrier-promoting effect may be of interest in the context of obesity. Obesity is associated with reduced gut barrier function, increasing the translocation of proinflammatory gut content to the circulation. This phenomenon constitutes a strong driver of obesity-associated systemic low-grade inflammation, which in turn plays a major role in the development of most obesity-associated complications. Thus, the intestinotrophic and gut barrier-improving effect of GLP-2, which in obese rodent models shows strong anti-inflammatory potential, may, in combination with food intake-reducing strategies, e.g., GLP-1 receptor (GLP-1) agonism, be able to rectify core pathophysiological mechanism of obesity. Here, we provide an overview of GLP-2 physiology in the context of obesity pathophysiology and review the pharmacological potential of GLP-2R activation in the management of obesity and related comorbidities.

A meta-analysis approach for annotation and identification of lncRNAs controlling perirenal fat deposition in suckling lambs

Long non-coding RNAs (lncRNAs) are being studied in farm animals due to their association with traits of economic interest, such as fat deposition. Based on the analysis of perirenal fat transcriptomes, this research explored the relevance of these regulatory elements to fat deposition in suckling lambs. To that end, meta-analysis techniques have been implemented to efficiently characterize and detect differentially expressed transcripts from two different RNA-seq datasets, one including samples of two sheep breeds that differ in fat deposition features, Churra and Assaf (n = 14), and one generated from Assaf suckling lambs with different fat deposition levels (n = 8). The joint analysis of the 22 perirenal fat RNA-seq samples with the FEELnc software allowed the detection of 3953 novel lncRNAs. After the meta-analysis, 251 differentially expressed genes were identified, 21 of which were novel lncRNAs. Additionally, a co-expression analysis revealed that, in suckling lambs, lncRNAs may play a role in controlling angiogenesis and thermogenesis, processes highlighted in relation to high and low fat deposition levels, respectively. Overall, while providing information that could be applied for the improvement of suckling lamb carcass traits, this study offers insights into the biology of perirenal fat deposition regulation in mammals.

Neuregulin 4 mediates the metabolic benefits of mild cold exposure by promoting beige fat thermogenesis

Interorgan crosstalk via secreted hormones and metabolites is a fundamental aspect of mammalian metabolic physiology. Beyond the highly specialized endocrine cells, peripheral tissues are emerging as an important source of metabolic hormones that influence energy and nutrient metabolism and contribute to disease pathogenesis. Neuregulin 4 (Nrg4) is a fat-derived hormone that protects mice from nonalcoholic steatohepatitis (NASH) and NASH-associated liver cancer by shaping hepatic lipid metabolism and the liver immune microenvironment. Despite its enriched expression in brown fat, whether NRG4 plays a role in thermogenic response and mediates the metabolic benefits of cold exposure are areas that remain unexplored. Here we show that Nrg4 expression in inguinal white adipose tissue (iWAT) is highly responsive to chronic cold exposure. Nrg4 deficiency impairs beige fat induction and renders mice more susceptible to diet-induced metabolic disorders under mild cold conditions. Using mice with adipocyte and hepatocyte-specific Nrg4 deletion, we reveal that adipose tissue-derived NRG4, but not hepatic NRG4, is essential for beige fat induction following cold acclimation. Furthermore, treatment with recombinant NRG4-Fc fusion protein promotes beige fat induction in iWAT and improves metabolic health in mice with diet-induced obesity. These findings highlight a critical role of NRG4 in mediating beige fat induction and preserving metabolic health under mild cold conditions.

Endothelial Dysfunction in Obesity and Therapeutic Targets

Parallel to the increasing prevalence of obesity in the world, the mortality from cardiovascular disease has also increased. Low-grade chronic inflammation in obesity disrupts vascular homeostasis, and the dysregulation of adipocyte-derived endocrine and paracrine effects contributes to endothelial dysfunction. Besides the adipose tissue inflammation, decreased nitric oxide (NO)-bioavailability, insulin resistance (IR), and oxidized low-density lipoproteins (oxLDLs) are the main factors contributing to endothelial dysfunction in obesity and the development of cardiorenal metabolic syndrome. While normal healthy perivascular adipose tissue (PVAT) ensures the dilation of blood vessels, obesity-associated PVAT leads to a change in the profile of the released adipo-cytokines, resulting in a decreased vasorelaxing effect. Higher stiffness parameter β, increased oxidative stress, upregulation of pro-inflammatory cytokines, and nicotinamide adenine dinucleotide phosphate (NADP) oxidase in PVAT turn the macrophages into pro-atherogenic phenotypes by oxLDL-induced adipocyte-derived exosome-macrophage crosstalk and contribute to the endothelial dysfunction. In clinical practice, carotid ultrasound, higher leptin levels correlate with irisin over-secretion by human visceral and subcutaneous adipose tissues, and remnant cholesterol (RC) levels predict atherosclerotic disease in obesity. As a novel therapeutic strategy for cardiovascular protection, liraglutide improves vascular dysfunction by modulating a cyclic adenosine monophosphate (cAMP)-independent protein kinase A (PKA)-AMP-activated protein kinase (AMPK) pathway in PVAT in obese individuals. Because the renin-angiotensin-aldosterone system (RAAS) activity, hyperinsulinemia, and the resultant IR play key roles in the progression of cardiovascular disease in obesity, RAAS-targeted therapies contribute to improving endothelial dysfunction. By contrast, arginase reciprocally inhibits NO formation and promotes oxidative stress. Thus, targeting arginase activity as a key mediator in endothelial dysfunction has therapeutic potential in obesity-related vascular comorbidities. Obesity-related endothelial dysfunction plays a pivotal role in the progression of type 2 diabetes (T2D). The peroxisome proliferator-activated receptor gamma (PPARγ) agonist, rosiglitazone (thiazolidinedione), is a popular drug for treating diabetes; however, it leads to increased cardiovascular risk. Selective sodium-glucose co-transporter-2 (SGLT-2) inhibitor empagliflozin (EMPA) significantly improves endothelial dysfunction and mortality occurring through redox-dependent mechanisms. Although endothelial dysfunction and oxidative stress are alleviated by either metformin or EMPA, currently used drugs to treat obesity-related diabetes neither possess the same anti-inflammatory potential nor simultaneously target endothelial cell dysfunction and obesity equally. While therapeutic interventions with glucagon-like peptide-1 (GLP-1) receptor agonist liraglutide or bariatric surgery reverse regenerative cell exhaustion, support vascular repair mechanisms, and improve cardiometabolic risk in individuals with T2D and obesity, the GLP-1 analog exendin-4 attenuates endothelial endoplasmic reticulum stress.

Adipsin inhibits Irak2 mitochondrial translocation and improves fatty acid β-oxidation to alleviate diabetic cardiomyopathy

BACKGROUND

Diabetic cardiomyopathy (DCM) causes the myocardium to rely on fatty acid β-oxidation for energy. The accumulation of intracellular lipids and fatty acids in the myocardium usually results in lipotoxicity, which impairs myocardial function. Adipsin may play an important protective role in the pathogenesis of DCM. The aim of this study is to investigate the regulatory effect of Adipsin on DCM lipotoxicity and its molecular mechanism.

METHODS

A high-fat diet (HFD)-induced type 2 diabetes mellitus model was constructed in mice with adipose tissue-specific overexpression of Adipsin (Adipsin-Tg). Liquid chromatography-tandem mass spectrometry (LC-MS/MS), glutathione-S-transferase (GST) pull-down technique, Co-immunoprecipitation (Co-IP) and immunofluorescence colocalization analyses were used to investigate the molecules which can directly interact with Adipsin. The immunocolloidal gold method was also used to detect the interaction between Adipsin and its downstream modulator.

RESULTS

The expression of Adipsin was significantly downregulated in the HFD-induced DCM model (P < 0.05). Adipose tissue-specific overexpression of Adipsin significantly improved cardiac function and alleviated cardiac remodeling in DCM (P < 0.05). Adipsin overexpression also alleviated mitochondrial oxidative phosphorylation function in diabetic stress (P < 0.05). LC-MS/MS analysis, GST pull-down technique and Co-IP studies revealed that interleukin-1 receptor-associated kinase-like 2 (Irak2) was a downstream regulator of Adipsin. Immunofluorescence analysis also revealed that Adipsin was co-localized with Irak2 in cardiomyocytes. Immunocolloidal gold electron microscopy and Western blotting analysis indicated that Adipsin inhibited the mitochondrial translocation of Irak2 in DCM, thus dampening the interaction between Irak2 and prohibitin (Phb)-optic atrophy protein 1 (Opa1) on mitochondria and improving the structural integrity and function of mitochondria (P < 0.05). Interestingly, in the presence of Irak2 knockdown, Adipsin overexpression did not further alleviate myocardial mitochondrial destruction and cardiac dysfunction, suggesting a downstream role of Irak2 in Adipsin-induced responses (P < 0.05). Consistent with these findings, overexpression of Adipsin after Irak2 knockdown did not further reduce the accumulation of lipids and their metabolites in the cardiac myocardium, nor did it enhance the oxidation capacity of cardiomyocytes expose to palmitate (PA) (P < 0.05). These results indicated that Irak2 may be a downstream regulator of Adipsin.

CONCLUSIONS

Adipsin improves fatty acid β-oxidation and alleviates mitochondrial injury in DCM. The mechanism is related to Irak2 interaction and inhibition of Irak2 mitochondrial translocation.

Adipose distribution patterns as prognostic factors in patients with HCC: A systematic review and meta-analysis

PURPOSES

The present meta-analysis aimed at identifying potential prognostic indicators associated with adipose distribution patterns for predicting the survival outcomes of patients diagnosed with hepatocellular carcinoma (HCC).

METHODS

A systematic retrieve was performed to identify studies investigating the association of adipose distribution patterns and the prognosis of HCC from the inception of PubMed, Embase, Cochrane Library, and Web of Science databases to May 25, 2023. The Newcastle-Ottawa scale was applied to assess the quality of included studies. The hazard ratios (HRs) and 95 % confidence intervals (CIs) of adipose distribution parameters of visceral, subcutaneous, and intermuscular adipose tissue were extracted. Univariate and multivariable meta-analyses were performed by Stata 12.0 to evaluate the relationship between these factors and overall survival (OS) and recurrence-free survival (RFS).

RESULTS

A total of 31 studies, comprising 7021 patients, including 2456 patients with HCV and 1466 patients with HBV were included. The pooled results indicated that only high visceral to subcutaneous adipose area ratio (VSR) (univariate analysis of OS: HR = 1.42, 95 % CI = 1.28-1.58, P < 0.001; multivariate analysis of OS: HR = 1.45, 95 % CI = 1.27-1.65, P < 0.001; univariate analysis of RFS: HR = 1.30, 95 % CI = 1.08-1.56, P = 0.006; multivariate analysis of RFS: HR = 1.36, 95 % CI = 1.10-1.67, P = 0.004) was both related to worse OS and RFS, with no significant heterogeneity observed.

CONCLUSION

Pretreatment VSR, as the sole parameter among adipose distribution-related factors exhibiting independent and stable associations with OS and RFS in patients with HCC, may hold promise as a potential prognostic factor for HCC.

Insights into the function of HDAC3 and NCoR1/NCoR2 co-repressor complex in metabolic diseases

Histone deacetylase 3 (HDAC3) and nuclear receptor co-repressor (NCoR1/2) are epigenetic regulators that play a key role in gene expression and metabolism. HDAC3 is a class I histone deacetylase that functions as a transcriptional co-repressor, modulating gene expression by removing acetyl groups from histones and non-histone proteins. NCoR1, on the other hand, is a transcriptional co-repressor that interacts with nuclear hormone receptors, including peroxisome proliferator-activated receptor gamma (PPARγ) and liver X receptor (LXR), to regulate metabolic gene expression. Recent research has revealed a functional link between HDAC3 and NCoR1 in the regulation of metabolic gene expression. Genetic deletion of HDAC3 in mouse models has been shown to improve glucose intolerance and insulin sensitivity in the liver, skeletal muscle, and adipose tissue. Similarly, genetic deletion of NCoR1 has improved insulin resistance and reduced adiposity in mouse models. Dysregulation of this interaction has been associated with the development of cardio-metabolic diseases such as cardiovascular diseases, obesity and type 2 diabetes, suggesting that targeting this pathway may hold promise for the development of novel therapeutic interventions. In this review, we summarize the current understanding of individual functions of HDAC3 and NCoR1/2 and the co-repressor complex formation (HDAC3/NCoR1/2) in different metabolic tissues. Further studies are needed to thoroughly understand the mechanisms through which HDAC3, and NCoR1/2 govern metabolic processes and the implications for treating metabolic diseases.

The development and benefits of metformin in various diseases

Metformin has been used for the treatment of type II diabetes mellitus for decades due to its safety, low cost, and outstanding hypoglycemic effect clinically. The mechanisms underlying these benefits are complex and still not fully understood. Inhibition of mitochondrial respiratory-chain complex I is the most described downstream mechanism of metformin, leading to reduced ATP production and activation of AMP-activated protein kinase (AMPK). Meanwhile, many novel targets of metformin have been gradually discovered. In recent years, multiple pre-clinical and clinical studies are committed to extend the indications of metformin in addition to diabetes. Herein, we summarized the benefits of metformin in four types of diseases, including metabolic associated diseases, cancer, aging and age-related diseases, neurological disorders. We comprehensively discussed the pharmacokinetic properties and the mechanisms of action, treatment strategies, the clinical application, the potential risk of metformin in various diseases. This review provides a brief summary of the benefits and concerns of metformin, aiming to interest scientists to consider and explore the common and specific mechanisms and guiding for the further research. Although there have been countless studies of metformin, longitudinal research in each field is still much warranted.

Adipose Tissue Caveolin-1 Upregulation in Obesity Involves TNF-α/NF-κB Mediated Signaling

Obesity is characterized by chronic low-grade inflammation. Obese people have higher levels of caveolin-1 (CAV1), a structural and functional protein present in adipose tissues (ATs). We aimed to define the inflammatory mediators that influence CAV1 gene regulation and the associated mechanisms in obesity. Using subcutaneous AT from 27 (7 lean and 20 obese) normoglycemic individuals, in vitro human adipocyte models, and in vivo mice models, we found elevated CAV1 expression in obese AT and a positive correlation between the gene expression of CAV1, tumor necrosis factor-alpha (TNF-α), and the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). CAV1 gene expression was associated with proinflammatory cytokines and chemokines and their cognate receptors (r ≥ 0.447, p ≤ 0.030), but not with anti-inflammatory markers. CAV1 expression was correlated with CD163, indicating a prospective role for CAV1 in the adipose inflammatory microenvironment. Unlike wild-type animals, mice lacking TNF-α exhibited reduced levels of CAV1 mRNA/proteins, which were elevated by administering exogenous TNF-α. Mechanistically, TNF-α induces CAV1 gene transcription by mediating NF-κB binding to its two regulatory elements located in the CAV1 proximal regulatory region. The interplay between CAV1 and the TNF-α signaling pathway is intriguing and has potential as a target for therapeutic interventions in obesity and metabolic syndromes.

VLDL-VLDLR axis facilitates brown fat thermogenesis through replenishment of lipid fuels and PPARβ/δ activation

In mammals, brown adipose tissue (BAT) is specialized to conduct non-shivering thermogenesis for survival under cold acclimation. Although emerging evidence suggests that lipid metabolites are essential for heat generation in cold-activated BAT, the underlying mechanisms of lipid uptake in BAT have not been thoroughly understood. Here, we show that very-low-density lipoprotein (VLDL) uptaken by VLDL receptor (VLDLR) plays important roles in thermogenic execution in BAT. Compared with wild-type mice, VLDLR knockout mice exhibit impaired thermogenic features. Mechanistically, VLDLR-mediated VLDL uptake provides energy sources for mitochondrial oxidation via lysosomal processing, subsequently enhancing thermogenic activity in brown adipocytes. Moreover, the VLDL-VLDLR axis potentiates peroxisome proliferator activated receptor (PPAR)β/δ activity with thermogenic gene expression in BAT. Accordingly, VLDL-induced thermogenic capacity is attenuated in brown-adipocyte-specific PPARβ/δ knockout mice. Collectively, these data suggest that the VLDL-VLDLR axis in brown adipocytes is a key factor for thermogenic execution during cold exposure.

Body fatness associations with cancer: evidence from recent epidemiological studies and future directions

This narrative review highlights current evidence linking greater body fatness to risk of various cancers, with focus on evidence from recent large cohort studies and pooled analyses of cohort studies as well as Mendelian randomization studies (which utilized genetic variants associated with body mass index to debrief the causal effect of higher body fatness on cancer risk). This review also provides insights into the biological mechanisms underpinning the associations. Data from both observational and Mendelian randomization studies support the associations of higher body mass index with increased risk of many cancers with the strongest evidence for digestive system cancers, including esophageal, stomach, colorectal, liver, gallbladder, and pancreatic cancer, as well as kidney, endometrial, and ovarian (weak association) cancer. Evidence from observational studies suggests that greater body fatness has contrasting effects on breast cancer risk depending on menopausal status and on prostate cancer risk depending on disease stage. Experimental and Mendelian randomization studies indicate that adiponectin, insulin, and sex hormone pathways play an important role in mediating the link between body fatness and cancer risk. The possible role of specific factors and pathways, such as other adipocytokines and hormones and the gut microbiome in mediating the associations between greater body fatness and cancer risk is yet uncertain and needs investigation in future studies. With rising prevalence of overweight and obesity worldwide, the proportion of cancer caused by excess body fatness is expected to increase. There is thus an urgent need to identify efficient ways at the individual and societal level to improve diet and physical activity patterns to reduce the burden of obesity and accompanying comorbidities, including cancer.

IL-6 and IL-8: An Overview of Their Roles in Healthy and Pathological Pregnancies

Interleukin-6 (IL-6) is an acknowledged inflammatory cytokine with a pleiotropic action, mediating innate and adaptive immunity and multiple physiological processes, including protective and regenerative ones. IL-8 is a pro-inflammatory CXC chemokine with a primary function in attracting and activating neutrophils, but also implicated in a variety of other cellular processes. These two ILs are abundantly expressed at the feto-maternal interface over the course of a pregnancy and have been shown to participate in numerous pregnancy-related events. In this review, we summarize the literature data regarding their role in healthy and pathological pregnancies. The general information related to IL-6 and IL-8 functions is followed by an overview of their overall expression in cycling endometrium and at the feto-maternal interface. Further, we provide an overview of their involvement in pregnancy establishment and parturition. Finally, the implication of IL-6 and IL-8 in pregnancy-associated pathological conditions, such as pregnancy loss, preeclampsia, gestational diabetes mellitus and infection/inflammation is discussed.

Dectin-1 as a Potential Inflammatory Biomarker for Metabolic Inflammation in Adipose Tissue of Individuals with Obesity

In obesity, macrophage activation and infiltration in adipose tissue (AT) underlie chronic low-grade inflammation-induced insulin resistance. Although dectin-1 is primarily a pathogen recognition receptor and innate immune response modulator, its role in metabolic syndromes remains to be clarified. This study aimed to investigate the dectin-1 gene expression in subcutaneous AT in the context of obesity and associated inflammatory markers. Subcutaneous AT biopsies were collected from 59 nondiabetic (lean/overweight/obese) individuals. AT gene expression levels of dectin-1 and inflammatory markers were determined via real-time reverse transcriptase-quantitative polymerase chain reaction. Dectin-1 protein expression was assessed using immunohistochemistry. Plasma lipid profiles were measured by ELISA. AT dectin-1 transcripts and proteins were significantly elevated in obese as compared to lean individuals. AT dectin-1 transcripts correlated positively with body mass index and fat percentage (r ≥ 0.340, p ≤ 0.017). AT dectin-1 RNA levels correlated positively with clinical parameters, including plasma C-reactive protein and CCL5/RANTES, but negatively with that of adiponectin. The expression of dectin-1 transcripts was associated with that of various proinflammatory cytokines, chemokines, and their cognate receptors (r ≥ 0.300, p ≤ 0.05), but not with anti-inflammatory markers. Dectin-1 and members of the TLR signaling cascade were found to be significantly associated, suggesting an interplay between the two pathways. Dectin-1 expression was correlated with monocyte/macrophage markers, including CD16, CD68, CD86, and CD163, suggesting its monocytes/macrophage association in an adipose inflammatory microenvironment. Dectin-1 expression was independently predicted by CCR5, CCL20, TLR2, and MyD88. In conclusion, dectin-1 may be regarded as an AT biomarker of metabolic inflammation in obesity.

Adipose tissue macrophage in obesity-associated metabolic diseases

Adipose tissue macrophage (ATM) has been appreciated for its critical contribution to obesity-associated metabolic diseases in recent years. Here, we discuss the regulation of ATM on both metabolic homeostatsis and dysfunction. In particular, the macrophage polarization and recruitment as well as the crosstalk between ATM and adipocyte in thermogenesis, obesity, insulin resistance and adipose tissue fibrosis have been reviewed. A better understanding of how ATM regulates adipose tissue remodeling may provide novel therapeutic strategies against obesity and associated metabolic diseases.

Adipocyte differentiation between obese and lean conditions depends on changes in miRNA expression

Adipogenesis is the process by which precursor cells, preadipocytes (preACs), differentiate into adipocytes (ACs). Here, we investigated differentially expressed miRNAs (DEMs) between the two conditions to understand the regulatory role of miRNAs in altering adipogenesis-related mRNAs. A total of 812 and 748 DEMs were obtained in lean and obese conditions, respectively. The up- and downregulated DEMs were highly concordant with each other in both lean and obese conditions; however, DEMs related to adipogenesis in obese conditions were more strongly downregulated than DEMs related to adipogenesis in lean conditions. There were more obese-specific downregulated DEMs than lean-specific downregulated DEMs; in contrast, there were more lean-specific upregulated DEMs than obese-specific upregulated DEMs. Approximately 45% of DEMs were mapped to the list of miRNA-target mRNA pairs when DEMs were matched to the experimentally validated list of miRNA-target mRNA information of miRTarBase. Many of the target mRNAs were differentially expressed genes (DEGs) with functions in processes such as inflammatory responses and fat metabolism. In particular, a total of 25 miRNAs that target three upregulated adipogenesis-associated inflammatory genes (IL-6, TNF-α, and IL-1β) were commonly altered during adipogenesis. Taken together, our study reveals the types of adipogenesis-related miRNAs that are altered and the degree to which they influence healthy or pathogenic adipogenesis.

Non-Alcoholic Fatty Liver Disease and Metabolic Syndrome in Women: Effects of Lifestyle Modifications

Non-alcoholic fatty liver disease (NAFLD) is the most widespread liver disease, characterized by fatty acids liver accumulation and subsequent fibrosis. NAFLD prevalence ranges from 80% to 90% in obese subjects and is estimated to be around 50% in patients with metabolic syndrome. In this clinical scenario, diet and lifestyle modifications can play an important role. There are several imaging techniques that can accurately diagnose fatty liver. Recently, ultrasound has acquired a leading role in the diagnosis and follow-up of fatty liver disease. Furthermore, elastosonography represents a valid alternative to liver biopsy. Shear wave elastosonography evaluates the elastic and mechanical properties of liver tissue. The aim is to evaluate the effects of lifestyle and nutritional interventions and a loss of body weight during hepatic steatosis through ultrasonographic and elastosonographic techniques. Thirty-two female subjects with metabolic syndrome were subjected to clinical, anthropometric, and laboratory assessments, as well as abdominal ultrasonographic/elastosonographic measurements taken from enrollment time (T0) and after 3 months (T1) of lifestyle modifications. After 3 months of lifestyle changes, significant weight loss was observed, with a marked improvement in all adiposity indices. The laboratory parameters at T1 showed significant decreases in total and LDL cholesterol, triglycerides, basal blood glucose, 120 min glycaemia, basal insulin and HOMA Index (p < 0.001). A similar improvement was observed at T1 for steatosis degree (p < 0.01) and elastosonographic measurements (Kpa p < 0.001). The linear regression analysis of the baseline conditions documented that the size of the liver positively correlated with body weight, BMI, neck and waist circumferences, waist to height ratio (WhtR), insulin and HOMA Index, fat mass and visceral fat, and steatosis grade. After 3 months, the liver size showed improvement with positive correlations to all previous variables. Hepatic stiffness (Kpa) positively correlated with neck circumference, visceral fat, and ALT, with basal insulin, gamma-GT, and AST, and with waist circumference, WhtR, and fat mass. The degree of steatosis was positively correlated with more variables and with greater statistical significance at T1 with respect to T0. Particularly, the positive correlations between the degree of steatosis and neck circumference (p < 0.001), HOMA Index, and triglycerides (p < 0.001) appeared to be very significant. NAFLD management in women with metabolic syndrome should be focused on lifestyle modifications. Moreover, liver involvement and improvement at follow-up could be evaluated in a non-invasive manner through ultrasonographic and elastosonographic techniques.

SREBP1c-PARP1 axis tunes anti-senescence activity of adipocytes and ameliorates metabolic imbalance in obesity

Emerging evidence indicates that the accretion of senescent cells is linked to metabolic disorders. However, the underlying mechanisms and metabolic consequences of cellular senescence in obesity remain obscure. In this study, we found that obese adipocytes are senescence-susceptible cells accompanied with genome instability. Additionally, we discovered that SREBP1c may play a key role in genome stability and senescence in adipocytes by modulating DNA-damage responses. Unexpectedly, SREBP1c interacted with PARP1 and potentiated PARP1 activity during DNA repair, independent of its canonical lipogenic function. The genetic depletion of SREBP1c accelerated adipocyte senescence, leading to immune cell recruitment into obese adipose tissue. These deleterious effects provoked unhealthy adipose tissue remodeling and insulin resistance in obesity. In contrast, the elimination of senescent adipocytes alleviated adipose tissue inflammation and improved insulin resistance. These findings revealed distinctive roles of SREBP1c-PARP1 axis in the regulation of adipocyte senescence and will help decipher the metabolic significance of senescence in obesity.

3-tert-Butyl-4-hydroxyanisole Impairs Hepatic Lipid Metabolism in Male Mice Fed with a High-Fat Diet

3-tert-Butyl-4-hydroxyanisole (3-BHA), one of the widely used food antioxidants, has been found to act as a potential obesogen by promoting adipogenesis in vitro and inducing white adipose tissue development in vivo. Whether 3-BHA-induced visceral obesity was accompanied by a disruption of hepatic lipid homeostasis in mammals remained unclear. In this study, we evaluated the effect of 3-BHA on the development of nonalcoholic fatty liver disease (NAFLD) in male C57BL/6J mice. After 18 weeks of oral administration of 10 mg/kg 3-BHA, the mice fed with a high-fat diet (HFD) had higher hepatic triglyceride concentrations (0.32 mg/mg protein) and severer steatosis (1.57 for the NAFLD score) than the control ones. The in vivo hepatic lipid deposition disturbed by 3-BHA was transcriptionally regulated by the genes involved in lipid uptake, de novo lipogenesis, fatty acid oxidation, and lipid export. The in vitro studies further confirmed that 24 h of exposure to 50 μM 3-BHA could induce intracellular oleic acid (OA) uptake and triglyceride accumulation (1.5-fold of the OA control) in HepG2 cells. Lipidomic analysis indicated the perturbation of 3-BHA in the levels of 30 lipid species related to sphingolipids, glycerophospholipids, and glycerolipids under HFD conditions. The findings herein first revealed the disruption effect of 3-BHA on hepatic lipid homeostasis, thus exacerbating the development of HFD-induced NAFLD.

Obesity: A Chronic Low-Grade Inflammation and Its Markers

As the prevalence of obesity continues to rise, the world is facing a major public health concern. Obesity is a complex disease associated with an increase in several inflammatory markers, leading to chronic low-grade inflammation. Of multifactorial etiology, it is often used as a measurement of morbidity and mortality. There remains much unknown regarding the association between obesity and inflammation. This review seeks to compile scientific literature on obesity and its associated inflammatory markers in chronic disease and further discusses the role of adipose tissue, macrophages, B-cells, T-cells, fatty acids, amino acids, adipokines, and hormones in obesity. Data were obtained using PubMed and Google Scholar. Obesity, inflammation, immune cells, hormones, fatty acids, and others were search words used to acquire relevant articles. Studies suggest brown adipose tissue is negatively associated with body mass index (BMI) and body fat percentage. Researchers also found the adipose tissue of lean individuals predominantly secretes anti-inflammatory markers, while in obese individuals more pro-inflammatory markers are secreted. Many studies found that adipose tissue in obese individuals showed a shift in immune cells from anti-inflammatory M2 macrophages to pro-inflammatory M1 macrophages, which was also correlated with insulin resistance. Obese individuals generally present with higher levels of hormones such as leptin, visfatin, and resistin. With obesity on the rise globally, it is predicted that severe obesity will become most common amongst low-income adults, black individuals, and women by 2030, making the need for intervention urgent. Further investigation into the association between obesity and inflammation is required to understand the mechanism behind this disease.

Shared and distinct mechanisms of skeletal muscle atrophy: A narrative review

Maintenance of skeletal muscle mass and function is an incredibly nuanced balance of anabolism and catabolism that can become distorted within different pathological conditions. In this paper we intend to discuss the distinct intracellular signaling events that regulate muscle protein atrophy for a given clinical occurrence. Aside from the common outcome of muscle deterioration, several conditions have at least one or more distinct mechanisms that creates unique intracellular environments that facilitate muscle loss. The subtle individuality to each of these given pathologies can provide both researchers and clinicians with specific targets of interest to further identify and increase the efficacy of medical treatments and interventions.

Complement Factor D as a Strategic Target for Regulating the Alternative Complement Pathway

The complement system is central to first-line defense against invading pathogens. However, excessive complement activation and/or the loss of complement regulation contributes to the development of autoimmune diseases, systemic inflammation, and thrombosis. One of the three pathways of the complement system, the alternative complement pathway, plays a vital role in amplifying complement activation and pathway signaling. Complement factor D, a serine protease of this pathway that is required for the formation of C3 convertase, is the rate-limiting enzyme. In this review, we discuss the function of factor D within the alternative pathway and its implication in both healthy physiology and disease. Because the alternative pathway has a role in many diseases that are characterized by excessive or poorly mediated complement activation, this pathway is an enticing target for effective therapeutic intervention. Nonetheless, although the underlying disease mechanisms of many of these complement-driven diseases are quite well understood, some of the diseases have limited treatment options or no approved treatments at all. Therefore, in this review we explore factor D as a strategic target for advancing therapeutic control of pathological complement activation.

Deletion of the Feeding-Induced Hepatokine TSK Ameliorates the Melanocortin Obesity Syndrome

Work in recent decades has established that metabolic hormones released by endocrine cells and diverse other cell types serve to regulate nutrient intake and energy homeostasis. Tsukushi (TSK) is a leucine-rich repeat-containing protein secreted primarily by the liver that exerts an inhibitory effect on brown fat sympathetic innervation and thermogenesis. Despite this, physiological regulation of TSK and the mechanisms underlying its effects on energy balance remain poorly understood. Here we show that hepatic expression and plasma concentrations of TSK are induced by feeding and regulated by melanocortin-4 receptor (MC4R) signaling. We generated TSK and MC4R-double-knockout mice to elucidate the nature of cross talk between TSK and the central regulatory circuit of energy balance. Remarkably, TSK inactivation restores energy balance, ameliorates hyperphagia, and improves metabolic health in MC4R-deficient mice. TSK ablation enhances thermogenic gene expression in brown fat, dampens obesity-association inflammation in the liver and adipose tissue, and protects MC4R-null mice from diet-induced nonalcoholic steatohepatitis. At the cellular level, TSK deficiency augments feeding-induced c-Fos expression in the paraventricular nucleus of the hypothalamus. These results illustrate physiological cross talk between TSK and the central regulatory circuit in maintaining energy balance and metabolic homeostasis.

Oxidative Stress Biomarkers in the Relationship between Type 2 Diabetes and Air Pollution

The incidence and prevalence of type 2 diabetes have increased in the last decades and are expected to further grow in the coming years. Chronic hyperglycemia triggers free radical generation and causes increased oxidative stress, affecting a number of molecular mechanisms and cellular pathways, including the generation of advanced glycation end products, proinflammatory and procoagulant effects, induction of apoptosis, vascular smooth-muscle cell proliferation, endothelial and mitochondrial dysfunction, reduction of nitric oxide release, and activation of protein kinase C. Among type 2 diabetes determinants, many data have documented the adverse effects of environmental factors (e.g., air pollutants) through multiple exposure-induced mechanisms (e.g., systemic inflammation and oxidative stress, hypercoagulability, and endothelial and immune responses). Therefore, here we discuss the role of air pollution in oxidative stress-related damage to glycemic metabolism homeostasis, with a particular focus on its impact on health. In this context, the improvement of new advanced tools (e.g., omic techniques and the study of epigenetic changes) may provide a substantial contribution, helping in the evaluation of the individual in his biological totality, and offer a comprehensive assessment of the molecular, clinical, environmental, and epidemiological aspects.

Successful weight loss reduces endothelial activation in individuals with severe obesity participating in a multimodal weight loss program

INTRODUCTION

Endothelial dysfunction is a very common finding in obesity and metabolic syndrome. The aim of our study was to investigate if longterm weight reduction (WR) success may reverse endothelial activation in individuals with severe obesity participating in a multimodal WR program.

METHODS

Participants with obesity (øBMI 40.3 ±7.5 kg/m²) underwent a standardized non-surgical 1-year WR program. Carotid artery studies and determination of endothelial function biomarkers were performed at baseline and after 1 year. Individuals were dichotomized in "successful WR" (% WR≥10% of initial body weight) and "failed WR" (% WR<10% of initial body weight).

RESULTS

From 191 people with obesity, 115 achieved successful WR. Compared to controls without obesity (n=44) participants with obesity had higher carotid intima media thickness as well as higher sICAM-1, sE-selectin, MMP-9, hsCRP and IL-6 levels. After 12 months follow up delta values of inflammation and endothelial adhesion markers were significantly different between participants with obesity and successful WR and participants with obesity and failed WR, in favour of the successful WR group (mean ± standard deviation): ΔhsCRP (-5.2 mg/L ±7.8 vs. 1.1 mg/L ±5.1, P<0.001; P_adj=0.009), ΔIL-6 (-1.0 pg/mL ±3.4 vs. 0.5 pg/mL ±2.6, P<0.001; P_adj=0.057), ΔsE-selectin (-19.0 ng/mL ±24.4 vs. 39.2 ng/mL ±20.3, P<0.001; P_adj<0.001), ΔsICAM-1 (-26.4 ng/mL ±68.8 vs. 10.6 ng/mL ±73.9, P=0.004; P_adj=0.805) and ΔoxLDL (-4 mg/dL ±30 vs. 5 mg/dL ±25, P=0.004; P_adj=0.473). In linear regression analysis reduction of BMI was significantly associated with improvement of several endothelial dysfunction biomarkers with the strongest effects for ΔsE-selectin and ΔhsCRP.

CONCLUSION

Our data corroborate the finding that obesity leads to endothelial dysfunction. Furthermore, successful non-surgical WR may at least partially reverse endothelial activation implicating cardiovascular health benefits of WR in people with severe obesity.

Growth arrest-specific 6 modulates adiponectin expression and insulin resistance in adipose tissue

AIMS/INTRODUCTION

Obesity is characterized by disturbed adipocytokine expression and insulin resistance in adipocytes. Growth arrest-specific 6 (GAS6) is a gene encoding the Gas6 protein, which is expressed in fibroblasts, and its related signaling might be associated with adipose tissue inflammation, glucose intolerance and insulin resistance. The aim of this study was to investigate the associations among Gas6, adipocytokines and insulin resistance in adipocytes.

MATERIALS AND METHODS

Mature Simpson Golabi Behmel Syndrome adipocytes were treated with high levels of insulin to mimic insulin resistance, and were examined for the expressions of Gas6, cytokines and adipocytokines from preadipocytes in differentiation. In an animal study, high-fat diet-induced obese mice were used to verify the Gas6 expression in vitro.

RESULTS

During the differentiation of adipocytes, the expression of Gas6 gradually decreased, and was obviously downregulated with adipocyte inflammation and insulin resistance. Gas6 levels were found to be in proportion to the expression of adiponectin, which has been regarded as closely relevant to improved insulin sensitivity after metformin treatment. Similar results were also confirmed in the animal study.

CONCLUSIONS

Our results suggest that Gas6 might modulate the expression of adiponectin, and might therefore be associated with insulin resistance in adipose tissues.

Hexane Extract of Chloranthus japonicus Increases Adipocyte Differentiation by Acting on Wnt/β-Catenin Signaling Pathway

Chloranthus japonicus has been heavily investigated for the treatment of various diseases. This paper attempts to show that Chloranthus japonicus can modulate adipocyte differentiation of preadipocytes. To establish this, we investigated the effects of Chloranthus japonicus extract in peroxisome proliferator-activated receptor γ (PPARγ) expression, adipogenesis, and the underlying molecular mechanisms in C3H10T1/2 and 3T3-L1 cells. Our data showed that Chloranthus japonicus methanol extract increased lipid accumulation and promoted adipocyte differentiation. Further studies on the fractionation with various solvents led to the identification of Chloranthus japonicus hexane extract (CJHE) as the most potent inducer of adipocyte differentiation. CJHE consistently increased lipid accumulation and adipocyte marker expression including Pparγ and it acted during the early stages of adipocyte differentiation. Mechanistic studies revealed that CJHE and a Wnt inhibitor similarly stimulated adipogenesis and were active in Wnt-selective reporter assays. The effects of CJHE were inhibited by Wnt3a protein treatment and were significantly blunted in β-catenin-silenced cells, further suggesting that CJHE acted on Wnt pathways to promote adipogenesis. We also showed that Chloranthus japonicus extracts generated from different plant parts similarly promoted adipocyte differentiation. These results identified Chloranthus japonicus as a pro-adipogenic natural product and suggest its potential use in metabolic syndrome.

Adipokines in vascular calcification

Adipose tissue (AT), a critical endocrine gland, is capable of producing and secreting abundant adipokines. Adipokines act on distant or adjacent organ tissues via paracrine, autocrine, and endocrine mechanism, which play attractive roles in the regulation of glycolipid metabolism and inflammatory response. Increasing evidence shows that adipokines can connect obesity with cardiovascular diseases by serving as promoters or inhibitors in vascular calcification. The chronic hypoxia in AT, caused by the adipocyte hypertrophy, is able to trigger imbalanced adipokine generation, which leads to apoptosis, osteogenic differentiation of vascular smooth muscle cells (VSMCs), vascular inflammation, and abnormal deposition of calcium and phosphorus in the vessel wall. The objectives of this review aim at providing a brief summary of the crucial influence of major adipokines on the formation and development of vascular calcification, which may contribute to better understanding these adipokines for establishing the appropriate therapeutic strategies to counteract obesity-associated vascular calcification.

Diabetic Ketoacidosis on Hospitalization with COVID-19 in a Previously Nondiabetic Patient: A Review of Pathophysiology

Hyperglycaemia during inpatient admission is indicative of higher morbidity and mortality risks in critically ill patients. The severe acute respiratory distress coronavirus 2 (SARS-CoV-2) has been reported to induce ketoacidosis and diabetic ketoacidosis (DKA) even in nondiabetic patients. The pathophysiology of the SARS-CoV-2 infection that can contribute to hyperglycaemia, and the exacerbated inflammatory cytokine storm can overlap with the metabolic chronic inflammatory state attributable to the metabolic syndrome, which underlies diabetes mellitus. In this report, we explore the possible pathophysiology and metabolic mechanisms that lead to metabolic acidosis in nondiabetic patients.

The Tumor-Fat Interface Volume of Breast Cancer on Pretreatment MRI Is Associated with a Pathologic Response to Neoadjuvant Chemotherapy

Simple Summary

Contact between a tumor and the adjacent fat is a potential biomarker to predict the therapy response in breast cancer, but it has not been quantitatively explored. In this study, we measured the direct contact between the tumor and adjacent fat using breast magnetic resonance imaging with machine learning and found that patients with a greater volume of contact between tumor and fat were less likely to have a complete pathological response. Our results suggest that the volume of the tumor–fat interface is a potential prognostic imaging biomarker to predict the treatment response to neoadjuvant chemotherapy.

Abstract

Adipocytes are active sources of numerous adipokines that work in both a paracrine and endocrine manner. It is not known that the direct contact between tumor and neighboring fat measured by pretreatment breast magnetic resonance imaging (MRI) affects treatment outcomes to neoadjuvant chemotherapy (NAC) in breast cancer patients. A biomarker quantifying the tumor–fat interface volume from pretreatment MRI was proposed and used to predict pathologic complete response (pCR) in breast cancer patients treated with NAC. The tumor–fat interface volume was computed with data-driven clustering using multiphasic MRI. Our approach was developed and validated in two cohorts consisting of 1140 patients. A high tumor–fat interface volume was significantly associated with a non-pCR in both the development and validation cohorts (p = 0.030 and p = 0.037, respectively). Quantitative measurement of the tumor–fat interface volume based on pretreatment MRI may be useful for precision medicine and subsequently influence the treatment strategy of patients.

Immunomodulatory and Antioxidative potentials of adipose-derived Mesenchymal stem cells isolated from breast versus abdominal tissue: a comparative study

BACKGROUND

Adipose-derived stem cells (ASCs) are considered ideal candidates for both research and cellular therapy due to ease of access, large yield, feasibility, and efficacy in preclinical and clinical studies. Unlike the subcutaneous abdominal fat depot, breast ASCs features are still not well recognized, limiting their possible therapeutic use. ASCs were found to exert immunomodulatory and antioxidative activities for maintaining homeostasis and functionality of diseased/damaged tissues. This study aims to investigate the immunomodulatory and antioxidative potentials of breast versus abdominal isolated ASCs to find out which anatomical site provides ASCs with better immunoregulatory and oxidative stress resistance capabilities.

METHODS

ASCs were isolated from abdominal and breast tissues. Gene expression analysis was conducted for a panel of immunomodulatory and antioxidative genes, as well as adipokines and proliferation genes. Flow cytometric analysis of a group of immunomodulatory surface proteins was also performed. Finally, the significantly expressed genes have undergone protein-protein interaction and functional enrichment in silico analyses.

RESULTS

Our results revealed similar morphological and phenotypic characteristics for both breast and abdominal ASCs. However, a significant elevation in the expression of two potent immunosuppressive genes, IL-10 and IDO as well as the expression of the multifaceted immunomodulatory adipokine, visfatin, was detected in breast versus abdominal ASCs. Moreover, a significant overexpression of the antioxidative genes, GPX1, SIRT5, and STAT3 and the proliferation marker, Ki67, was also observed in breast ASCs relative to abdominal ones. In silico analysis showed that both of the differentially upregulated immunomodulatory and antioxidative mediators integratively involved in multiple biological processes and pathways indicating their functional association.

CONCLUSION

Breast ASCs possess superior immunomodulatory and antioxidative capabilities over abdominal ASCs. Our findings shed light on the possible therapeutic applications of breast ASCs in immune-related and oxidative stress-associated diseases.

Elevated adipose tissue associated IL-2 expression in obesity correlates with metabolic inflammation and insulin resistance

Adipose tissue (AT) associated cytokines are involved in the development of chronic low-grade inflammation in obese individuals. IL-2, a pleiotropic cytokine, contributes to immune alterations during inflammation. However, the interaction between AT-IL-2 and other inflammatory biomolecules in obesity remains elusive. We investigated whether AT-IL-2 expression was associated with markers of inflammation and insulin resistance in overweight/obese individuals. Subcutaneous fat tissues were collected from 56 individuals (lean/overweight/obese) for RNA extraction. IL-2 and inflammatory mediators were quantified by qRT-PCR and immunohistochemistry. CRP was measured by ELISA. AT-IL-2 expression was higher in obese compared with lean individuals (P < 0.021) and correlated with BMI. IL-2 correlated with interleukins IL-8 and IL-12A (r = 0.333–0.481; p = 0.0001–0.029); as well as with chemokines and their receptors including CCL5, CCL19, CCR2 and CCR5 (r = 0.538–0.677; p < 0.0001). Moreover, IL-2 correlated with toll-like receptors (TLR2, TLR8, TLR10), interferon regulatory factor 5 (IRF5) and cluster of differentiation CD11c (r = 0.282–0.357; p < 0.039). Notably, IL-2 was associated positively with fasting blood glucose (FBG), HbA1c, TGL and CRP (r ≥ 0.423;P ≤ 0.007). In multiple regression analysis, IL-2 is an independent predictor of IL-8, IL-12A, TLR10, TGL and HbA1c. Overall, our data demonstrate that increased expression of the AT-IL-2, in obesity, may represent a novel biomarker for progression of metabolic inflammation and insulin-resistance.

Aging: a New Perspective on an Old Issue

The world is undergoing a profound demographic change with a rapid increase in the prevalence of aged individuals. The finitude of life, the burden of senescence and the search for strategies to prolong human life span have troubled humanity since ancient times. However, only in the past few decades we started to understand how organisms age and how life span can be manipulated. Here I give an historical perspective of the aging field and conclude with the notion that aging is controlled by signals from the adipose tissue which are tightly controlled by small non-coding RNAs such as miRNAs.

Transient receptor potential vanilloid 4 channels as therapeutic targets in diabetes and diabetes-related complications

With an estimated 425 million diabetes patients worldwide in 2019, type 2 diabetes has reached a pandemic proportion and represents a major unmet medical need. A key determinant of the development and progression of type 2 diabetes is pancreatic -cell dysfunction, including the loss of cell mass, the impairment of insulin biosynthesis and inadequate exocytosis. Recent studies have shown that transient receptor potential vanilloid 4 (TRPV4), a Ca2+ -permeable non-selective cation channel, is involved in -cell replication, insulin production and secretion. TRPV4 agonists have insulinotropic activity in pancreatic -cell lines, but the prolonged activation of TRPV4 leads to -cell dysfunction and death. In addition, TRPV4 is involved in a wide variety of pathophysiological activities, and has been reported to play an important role in diabetes-related complications, such as obesity, cardiovascular diseases, diabetic retinopathy, nephropathy and neuropathy. In a rodent type 2 diabetes model, Trpv4 agonists promote vasodilation and improve cardiovascular function, whereas Trpv4 antagonists reduce high-fat diet-induced obesity, insulin resistance, diabetic nephropathy, retinopathy and neuropathy. These findings raise interest in using TRPV4 as a therapeutic target for type 2 diabetes. In this review, we intend to summarize the latest findings regarding the role of TRPV4 in diabetes as well as diabetes-related conditions, and to evaluate its potential as a therapeutic target for diabetes and diabetes-related diseases.

Menopause-Associated Lipid Metabolic Disorders and Foods Beneficial for Postmenopausal Women

Menopause is clinically diagnosed as a condition when a woman has not menstruated for one year. During the menopausal transition period, there is an emergence of various lipid metabolic disorders due to hormonal changes, such as decreased levels of estrogens and increased levels of circulating androgens; these may lead to the development of metabolic syndromes including cardiovascular diseases and type 2 diabetes. Dysregulation of lipid metabolism affects the body fat mass, fat-free mass, fatty acid metabolism, and various aspects of energy metabolism, such as basal metabolic ratio, adiposity, and obesity. Moreover, menopause is also associated with alterations in the levels of various lipids circulating in the blood, such as lipoproteins, apolipoproteins, low-density lipoproteins (LDLs), high-density lipoproteins (HDL) and triacylglycerol (TG). Alterations in lipid metabolism and excessive adipose tissue play a key role in the synthesis of excess fatty acids, adipocytokines, proinflammatory cytokines, and reactive oxygen species, which cause lipid peroxidation and result in the development of insulin resistance, abdominal adiposity, and dyslipidemia. This review discusses dietary recommendations and beneficial compounds, such as vitamin D, omega-3 fatty acids, antioxidants, phytochemicals—and their food sources—to aid the management of abnormal lipid metabolism in postmenopausal women.

RNF20 Functions as a Transcriptional Coactivator for PPARγ by Promoting NCoR1 Degradation in Adipocytes

Adipose tissue is the key organ coordinating whole-body energy homeostasis. Although it has been reported that ring finger protein 20 (RNF20) regulates lipid metabolism in the liver and kidney, the roles of RNF20 in adipose tissue have not been explored. Here, we demonstrate that RNF20 promotes adipogenesis by potentiating the transcriptional activity of peroxisome proliferator-activated receptor-γ (PPARγ). Under normal chow diet feeding, Rnf20 defective (Rnf20 ^+/- ) mice exhibited reduced fat mass with smaller adipocytes compared with wild-type littermates. In addition, high-fat diet-fed Rnf20 ^+/- mice alleviated systemic insulin resistance accompanied by a reduced expansion of fat tissue. Quantitative proteomic analyses revealed significantly decreased levels of PPARγ target proteins in adipose tissue of Rnf20 ^+/- mice. Mechanistically, RNF20 promoted proteasomal degradation of nuclear corepressor 1 (NCoR1), which led to stimulation of the transcriptional activity of PPARγ. Collectively, these data suggest that RNF20-NCoR1 is a novel axis in adipocyte biology through fine-tuning the transcriptional activity of PPARγ.

Adipose tissue gene expression of CXCL10 and CXCL11 modulates inflammatory markers in obesity: implications for metabolic inflammation and insulin resistance

BACKGROUND

The CXCL subfamily of chemokines (CXCL9, CXCL10, and CXCL11; angiostatic chemokines) plays a key role in many inflammatory diseases. However, the expression of CXCLs in adipose tissue (AT) during obesity and association of these CXCLs with inflammatory markers and insulin resistance are poorly understood. Therefore, this study aimed to investigate the effects of CXCL gene expression on subcutaneous AT inflammatory markers and insulin resistance.

METHODS

Subcutaneous-fat biopsies were collected from 59 nondiabetic (lean/overweight/obese) individuals for RNA isolation. Expression levels of AT CXCL and inflammatory markers were determined by quantitative reverse transcriptase polymerase chain reaction (RT-qPCR). Biomedical parameters in the plasma were measured by enzyme-linked immunosorbent assay (ELISA). Insulin resistance was estimated using homeostatic model assessment (HOMA-IR).

RESULTS

AT CXCL expression was higher in obese compared with lean individuals (p < 0.05) and positively correlated with body mass index (BMI; r ⩾ 0.269, p < 0.05). Expression of CXCL9, CXCL10, and CXCL11 correlated significantly with various pro-inflammatory markers, including family members of interleukins, chemokines, and their prospective receptors (r ⩾ 0.339, p ⩽ 0.009), but not anti-inflammatory markers. CXCL11 expression correlated specifically with the expression of CCL5, CCL18, TLR3, TLR4, TLR8, IRF5, and NF-κB (r ⩾ 0.279, p ⩽ 0.039). Notably, CXCL11 was correlated with C-reactive protein (CRP), fasting blood glucose (FBG), and HOMA-IR. In multiple regression analysis, CXCL11 was identified as an independent predictor of CCL19, CCL5, IL-6, and TLR3.

CONCLUSION

These data suggest that the CXCL family members, specifically CXCL10 and CXCL11, are potential biomarkers for the onset of AT inflammation during obesity.

904 nm Low-Level Laser Irradiation Decreases Expression of Catabolism-Related Genes in White Adipose Tissue of Wistar Rats: Possible Roles of Laser on Metabolism

Background: Adipose tissue is the main energy storage tissue in the body. Its catabolic and anabolic responses depend on several factors, such as nutritional status, metabolic profile, and hormonal signaling. There are few studies addressing the effects of laser photobiomodulation (PBM) on adipose tissue and results are controversial. Objective: Our purpose was to investigate the metabolic effects of PBM on adipose tissue from Wistar rats supplemented or not with caffeine. Materials and methods: Wistar rats were divided into four groups: control (CTL), laser-treated [CTL (L)], caffeine (CAF), and caffeine+PBM [CAF (L)]. Blood was extracted for quantification of triglyceride and cholesterol levels and white adipose tissues were collected for analysis. We evaluated gene expression in the adipose tissue for the leptin receptor, lipase-sensitive hormone, tumor necrosis factor alpha, and beta adrenergic receptor. Results: We demonstrated that the low-level laser irradiation was able to increase the feed intake of the animals and the relative mass of the adipose tissue in the CTL (L) group compared with CTL. Laser treatment also increases serum triglycerides [CTL = 46.99 ± 5.87; CTL (L) = 57.46 ± 14.38; CAF = 43.98 ± 5.17; and CAF (L) = 56.9 ± 6.12; p = 0.007] and total cholesterol (CTL = 70.62 ± 6.80; CTL (L) = 79.41 ± 13.07; CAF = 71.01 ± 5.52; and CAF (L) = 79.23 ± 6.881; p = 0.003). Conclusions: Laser PBM decreased gene expression of the studied genes in the adipose tissue, indicating that PBM is able to block the catabolic responses of this tissue. Interestingly, the CAF (L) and CAF animals presented the same CLT (L) phenotype, however, without increasing the feed intake and the relative weight of the adipose tissue. The description of these phenomena opens a new perspective for the study of the action of low-level laser in adipose tissue.

Association between circulating neuregulin4 levels and diabetes mellitus: A meta-analysis of observational studies

INTRODUCTION

Neuregulin 4 (Nrg4) was proven as a brown fat-enriched secreted factor that can regulate glucose and lipid metabolism. However, the association between circulating Nrg4 levels and diabetes mellitus (DM) in human remains unclear. We conducted a meta-analysis to investigate association of circulating Nrg4 with DM.

METHODS

Observational studies comparing circulating Nrg4 levels in diabetes patients and health controls were included. Circulating Nrg4, correlation coefficients of clinical indices and circulating Nrg4 were pooled by meta-analysis.

RESULTS

Seven studies were included. The pooled results indicated there were no significant difference in the circulating Nrg4 between diabetes patients and controls (SMD = 0.18, 95%CI = -0.06 to 0.42, P = 0.143). However, diabetes patients had higher circulating Nrg4 than their controls in cross-sectional studies (SMD = 0.55, 95%CI = 0.36 to 0.73, P<0.001). None of the renal function and metabolic syndrome markers were correlated with circulating Nrg4, whereas the HbA1c and BMI were positively correlated (rs = 0.09, 95%CI = 0.03 to 0.16, P = 0.005; rs = 0.20, 95%CI = 0.07 to 0.34, P = 0.003; respectively).

CONCLUSION

Our findings suggested circulating Nrg4 may play a role in in the development of DM in cross-sectional studies and circulating Nrg4 might be associated with imbalance in glucose metabolism and obesity.

Role of edible mushroom as a potent therapeutics for the diabetes and obesity

Diabetes and obesity are the most frequently found disease worldwide. Several factors are responsible for obesity, i.e., imbalance in energy expenditure, environmental factors, feeding habit, lifestyle, etc., which can also be responsible for type 2 diabetes mellitus. There are several synthetic drugs available to combat these diseases which have some side effects on sufferers. Therefore, people are shifting towards inexpensive, effective, widely available natural and herbal medicines. Edible mushrooms, which have been used from ancient time to cure these diseases, contain anti-oxidant, fibers, triterpenoids, alkaloid, and other phytochemicals. Comatin, β-glucan, Tremellastin, and Lentinan KS-2 are active chemicals of mushrooms which show great effect on diabetes mellitus and obesity by modulating either cellular function or biochemical pathways. Here, in this review, we have discussed the potential role of edible mushrooms and its biochemicals in control of diabetes and obesity. Using Bioinformatics, we can find the specific targets of theses biochemicals, so that these can be more effective.

Twenty Novel Disease Group-Specific and 12 New Shared Macrophage Pathways in Eight Groups of 34 Diseases Including 24 Inflammatory Organ Diseases and 10 Types of Tumors

The mechanisms underlying pathophysiological regulation of tissue macrophage (Mφ) subsets remain poorly understood. From the expression of 207 Mφ genes comprising 31 markers for 10 subsets, 45 transcription factors (TFs), 56 immunometabolism enzymes, 23 trained immunity (innate immune memory) enzymes, and 52 other genes in microarray data, we made the following findings. (1) When 34 inflammation diseases and tumor types were grouped into eight categories, there was differential expression of the 31 Mφ markers and 45 Mφ TFs, highlighted by 12 shared and 20 group-specific disease pathways. (2) Mφ in lung, liver, spleen, and intestine (LLSI-Mφ) express higher M1 Mφ markers than lean adipose tissue Mφ (ATMφ) physiologically. (3) Pro-adipogenic TFs C/EBPα and PPARγ and proinflammatory adipokine leptin upregulate the expression of M1 Mφ markers. (4) Among 10 immune checkpoint receptors (ICRs), LLSI-Mφ and bone marrow (BM) Mφ express higher levels of CD274 (PDL-1) than ATMφ, presumably to counteract the M1 dominant status via its reverse signaling behavior. (5) Among 24 intercellular communication exosome mediators, LLSI- and BM- Mφ prefer to use RAB27A and STX3 than RAB31 and YKT6, suggesting new inflammatory exosome mediators for propagating inflammation. (6) Mφ in peritoneal tissue and LLSI-Mφ upregulate higher levels of immunometabolism enzymes than does ATMφ. (7) Mφ from peritoneum and LLSI-Mφ upregulate more trained immunity enzyme genes than does ATMφ. Our results suggest that multiple new mechanisms including the cell surface, intracellular immunometabolism, trained immunity, and TFs may be responsible for disease group-specific and shared pathways. Our findings have provided novel insights on the pathophysiological regulation of tissue Mφ, the disease group-specific and shared pathways of Mφ, and novel therapeutic targets for cancers and inflammations.

During Adipocyte Remodeling, Lipid Droplet Configurations Regulate Insulin Sensitivity through F-Actin and G-Actin Reorganization

Adipocytes have unique morphological traits in insulin sensitivity control. However, how the appearance of adipocytes can determine insulin sensitivity has not been understood. Here, we demonstrate that actin cytoskeleton reorganization upon lipid droplet (LD) configurations in adipocytes plays important roles in insulin-dependent glucose uptake by regulating GLUT4 trafficking. Compared to white adipocytes, brown/beige adipocytes with multilocular LDs exhibited well-developed filamentous actin (F-actin) structure and potentiated GLUT4 translocation to the plasma membrane in the presence of insulin. In contrast, LD enlargement and unilocularization in adipocytes downregulated cortical F-actin formation, eventually leading to decreased F-actin-to-globular actin (G-actin) ratio and suppression of insulin-dependent GLUT4 trafficking. Pharmacological inhibition of actin polymerization accompanied with impaired F/G-actin dynamics reduced glucose uptake in adipose tissue and conferred systemic insulin resistance in mice. Thus, our study reveals that adipocyte remodeling with different LD configurations could be an important factor to determine insulin sensitivity by modulating F/G-actin dynamics.

Organokines in disease

Studies have linked obesity, metabolic syndrome, type 2 diabetes, cardiovascular disease (CVD), nonalcoholic fatty liver disease (NAFLD) and dementia. Their relationship to the incidence and progression of these disease states suggests an interconnected pathogenesis involving chronic low-grade inflammation and oxidative stress. Metabolic syndrome represents comorbidities of central obesity, insulin resistance, dyslipidemia, hypertension and hyperglycemia associated with increased risk of type 2 diabetes, NAFLD, atherosclerotic CVD and neurodegenerative disease. As the socioeconomic burden for these diseases has grown signficantly with an increasing elderly population, new and alternative pharmacologic solutions for these cardiometabolic diseases are required. Adipose tissue, skeletal muscle and liver are central endocrine organs that regulate inflammation, energy and metabolic homeostasis, and the neuroendocrine axis through synthesis and secretion of adipokines, myokines, and hepatokines, respectively. These organokines affect each other and communicate through various endocrine, paracrine and autocrine pathways. The ultimate goal of this review is to provide a comprehensive understanding of organ crosstalk. This will include the roles of novel organokines in normal physiologic regulation and their pathophysiological effect in obesity, metabolic syndrome, type 2 diabetes, CVD, NAFLD and neurodegenerative disorders.

Testosterone Deficiency Caused by Castration Modulates Mitochondrial Biogenesis Through the AR/PGC1α/TFAM Pathway

Mammalian mitochondrial biogenesis is a complex process involving mitochondrial proliferation and differentiation. Mitochondrial DNA transcription factor A (TFAM), which encodes a major component of a protein-mitochondrial DNA (mtDNA) complex, is regulated by peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α). Testosterone is the primary male sex hormone and plays an increasingly important role in mammalian development through its interaction with androgen receptor (AR). However, the function of AR in mitochondrial biogenesis induced by testosterone deficiency has not been investigated. Here, we explored the molecular mechanism underlying the effect of testosterone deficiency on mitochondrial biogenesis using a Yorkshire boar model. Testosterone deficiency caused by castration induced changes in mtDNA copy numbers in various tissues, and AR showed the opposite tendency to that of mtDNA copy number, particularly in adipose tissues and muscle tissues. In addition, castration weakened the correlation of PGC1α and mtDNA copy number, while AR and TFAM showed a relatively high correlation in both control and castrated pigs. Furthermore, luciferase assays revealed that AR binds to potential AR elements in the TFAM promoter to promote TFAM expression. Taken together, testosterone may be involved in the pathway linking PGC1α to mitochondrial biogenesis through the interaction between AR and TFAM.

Adipokinome Signatures in Obese Mouse Models Reflect Adipose Tissue Health and Are Associated with Serum Lipid Composition

Adipocyte and hepatic lipid metabolism govern whole-body metabolic homeostasis, whereas a disbalance of de novo lipogenesis (DNL) in fat and liver might lead to obesity, with severe co-morbidities. Nevertheless, some obese people are metabolically healthy, but the “protective” mechanisms are not yet known in detail. Especially, the adipocyte-derived molecular mediators that indicate adipose functionality are poorly understood. We studied transgenic mice (alb-SREBP-1c) with a “healthy” obese phenotype, and obob mice with hyperphagia-induced “sick” obesity to analyze the impact of the tissue-specific DNL on the secreted proteins, i.e., the adipokinome, of the primary adipose cells by label-free proteomics. Compared to the control mice, adipose DNL is reduced in both obese mouse models. In contrast, the hepatic DNL is reduced in obob but elevated in alb-SREBP-1c mice. To investigate the relationship between lipid metabolism and adipokinomes, we formulated the “liver-to-adipose-tissue DNL” ratio. Knowledge-based analyses of these results revealed adipocyte functionality with proteins, which was involved in tissue remodeling or metabolism in the alb-SREBP-1c mice and in the control mice, but mainly in fibrosis in the obob mice. The adipokinome in “healthy” obesity is similar to that in a normal condition, but it differs from that in “sick” obesity, whereas the serum lipid patterns reflect the “liver-to-adipose-tissue DNL” ratio and are associated with the adipokinome signature.

Periprostatic fat adipokine expression is correlated with prostate cancer aggressiveness in men undergoing radical prostatectomy for clinically localized disease

OBJECTIVES

To investigate the relationship between periprostatic adipose tissue (PPAT) adipokine expression and prostate cancer (PCa) aggressiveness using both pathological features of radical prostatectomy (RP) and multiparametric magnetic resonance imaging ( MRI) variables.

PATIENTS AND METHODS

Sixty-nine men were recruited to assess immunohistochemical expression of tumour necrosis factor (TNF)α and vascular endothelial growth factor (VEGF) of periprostatic fat of RP specimens. Per cent immunopositivity was quantified on scanned slides using the Aperio Positive Pixel Count algorithm for PPAT TNFα, VEGF and androgen receptors. Periprostatic fat volume (PFV) was segmented on contiguous T₁ -weighted axial MRI slices from the level of the prostate base to apex. PFV was normalized to prostate volume (PV) to account for variations in PV (normalized PFV = PFV/PV). MRI quantitative values (K_ep , K_trans and apparent diffusion coefficient) were measured from the PCa primary lesion using Olea Sphere software. Patients were stratified into three groups according to RP Gleason score (GS): ≤6, 7(3 + 4) and ≥7(4 + 3).

RESULTS

The mean rank of VEGF and TNFα was significantly different between the groups [H(2) = 11.038, P = 0.004] and [H(2) = 13.086, P = 0.001], respectively. Patients with stage pT₃ had higher TNFα (18.2 ± 8.95) positivity than patients with stage pT₂ (13.27 ± 10.66; t [67] = -2.03, P = 0.047). TNFα expression significantly correlated with K_trans (ρ = 0.327, P = 0.023). TNFα (P = 0.043), and VEGF (P = 0.02) correlated with high grade PCa (GS ≥ 7) in RP specimens and also correlated significantly with upgrading of GS from biopsy to RP histology.

CONCLUSIONS

The expression levels of TNFα and VEGF on immunostaining significantly correlated with aggressivity of PCa. As biomarkers, these indicate the risk of having high grade PCa in men undergoing RP.

Health indicators and costs among outpatients according to physical activity level and obesity

OBJECTIVE

How biochemical variables influence the costs of the Brazilian National Healthcare System, according to body composition and physical activity.

METHODS

Participated in this study 168 patients. Biochemical variables were glucose, triglycerides, total cholesterol, high, low, very low density lipoprotein and C-reactive protein (CRP). For the cost analysis the medical records was analyzed. Physical activity was assessed through questionnaire. Body adiposity was assessed by body mass index. Four groups were defined according body adiposity and physical activity.

RESULTS

The active obese group had higher values of very low density lipoprotein and triglycerides when compared to the inactive obese. The non-obese inactive group had lower values of non-high density lipoprotein compared to the inactive obese. The non-obese active group presented lower insulin value when compared to the inactive obese. The inactive obese group presented higher values in the CRP when compared to the non-obese active and inactive groups when compared to non-obese and active obese group. There was a positive correlation between insulin, glucose, CRP and drug and total costs.

CONCLUSIONS

Biochemical variables were different according to body composition and physical activity. Insulin, glucose and CRP were related to cost in drugs and total costs.