Roles of Chemokines and Chemokine Receptors in Obesity-Associated Insulin Resistance and Nonalcoholic Fatty Liver Disease

The Role of microRNAs in Metabolic Syndrome-Related Oxidative Stress

Oxidative stress (OxS) is the cause and the consequence of metabolic syndrome (MetS), the incidence and economic burden of which is increasing each year. OxS triggers the dysregulation of signaling pathways associated with metabolism and epigenetics, including microRNAs, which are biomarkers of metabolic disorders. In this review, we aimed to summarize the current knowledge regarding the interplay between microRNAs and OxS in MetS and its components. We searched PubMed and Google Scholar to summarize the most relevant studies. Collected data suggested that different sources of OxS (e.g., hyperglycemia, insulin resistance (IR), hyperlipidemia, obesity, proinflammatory cytokines) change the expression of numerous microRNAs in organs involved in the regulation of glucose and lipid metabolism and endothelium. Dysregulated microRNAs either directly or indirectly affect the expression and/or activity of molecules of antioxidative signaling pathways (SIRT1, FOXOs, Keap1/Nrf2) along with effector enzymes (e.g., GPx-1, SOD1/2, HO-1), ROS producers (e.g., NOX4/5), as well as genes of numerous signaling pathways connected with inflammation, insulin sensitivity, and lipid metabolism, thus promoting the progression of metabolic imbalance. MicroRNAs appear to be important epigenetic modifiers in managing the delicate redox balance, mediating either pro- or antioxidant biological impacts. Summarizing, microRNAs may be promising therapeutic targets in ameliorating the repercussions of OxS in MetS.

Chemokines in Non-alcoholic Fatty Liver Disease: A Systematic Review and Network Meta-Analysis

Background: Previous results on the relationship between non-alcoholic fatty liver disease (NAFLD) and chemokine concentrations were inconsistent. The purpose of this network meta-analysis was to evaluate the link between chemokine system and NAFLD.

Methods: Relevant data, published not later than June 31, 2019, were searched in the databases of PubMed, Embase, Cochrane Library, and Web of Science. A network meta-analysis was used to rank the chemokines by surface under the cumulative ranking (SUCRA) probabilities. In addition, standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated as group differences in the chemokine concentrations.

Results: The search in the databases identified 46 relevant studies that investigated the relationship between 15 different chemokines and NAFLD using 4,753 patients and 4,059 controls. Results from the network meta-analysis showed that the concentrations of CCL2 and CXCL8 in the non-alcoholic fatty liver (NAFL) group was significantly higher than that in the control group (SMDs of 1.51 and 1.95, respectively), and the concentrations of CCL3, CCL4, CCL20, CXCL8, and CXCL10 in the non-alcoholic steatohepatitis (NASH) group was significantly higher than that in the control group (SMDs of 0.90, 2.05, 2.16, 0.91, and 1.46, respectively). SUCRA probabilities showed that CXCL8 had the highest rank in NAFL for all chemokines and CCL20 had the highest rank in NASH for all chemokines.

Conclusion: Elevated concentrations of CCL2, CCL4, CCL20, CXCL8, and CXCL10 may be associated with NAFL or NASH. In this regard, more population-based studies are needed to ascertain this hypothesis.

Systematic Review Registration: PROSPERO: CRD42020139373.

Transcriptome Analysis of Testis from HFD-Induced Obese Rats (Rattus norvigicus) Indicated Predisposition for Male Infertility

Obesity is a worldwide life-threatening metabolic disorder, associated with various chronic diseases, including male infertility. Obesity was induced by high fat diet (HFD), and testis RNA was used for the transcriptome analysis using RNAseq via Illumina NovaSeq 6000 System and NovaSeq 6000 Kit. Gene expression level was estimated as FPKM (Fragments Per Kilobase of transcript per Million mapped reads). Differential expressed genes (DEGs) were annotated against gene ontology (GO) and KEGG databases. More than 63.66 million reads per sample were performed with 100 bp cutoff and 6 Gb sequencing depth. Results of this study revealed that 267 GO terms (245 biological processes (BP), 14 cellular components (CC), eight molecular functions (MF)), and 89 KEGG pathways were significantly enriched. Moreover, total numbers of 136 genes were differentially expressed (107 upregulated, 29 downregulated) with |FC| ≥ 2 and bh adjusted <0.05. Interesting DEGs were detected, including obesity and lipid metabolism-related genes, immune response-related genes, cytochrome P450 genes, including aromatase were upregulated, whereas genes related to male fertility and fertilization, cell adhesion, and olfactory receptors were downregulated. The combined expression pattern of the DEGs in obese animals indicated an increase in cholesterol metabolism. Furthermore, high aromatase activity enhances the testosterone turnover into estradiol and lowers the testosterone/estradiol (T/E) ratio, which ultimately reduces fertility. In addition, downregulation of cadherens junction components genes leads to the pre-mature release of sperm from Sertoli cells resulting in the reduction of fertility. Moreover, the downregulation of olfactory receptor genes reduces the chemotaxis capacity of sperms in tracking the oocyte for fertilization, which reduces male fertility. Furthermore, various obesity molecular markers were detected in our transcriptome. The results of this study will enhance our understanding of the molecular network of obesity development, development of obesity novel molecular diagnosis markers, molecular bases of obesity-induced infertility, and the development of anti-obesity drugs.

Higher unacylated ghrelin and insulin sensitivity following dietary restriction and weight loss in obese humans

BACKGROUND & AIMS

Unacylated ghrelin (UnAG) modulates insulin sensitivity. Low plasma UnAG occurs in obesity and potentially contributes to obesity-associated insulin resistance. We hypothesized that improvements in insulin sensitivity in obese people induced by moderate caloric restriction (CR) may be paralleled and at least in part explained by concurrent increases in UnAG levels.

METHODS

20 general community obese people were randomly assigned to 16-week CR (n = 11) or control diet (n = 9). We investigated the impact of CR on the interaction between insulin sensitivity changes [area under the curve (AUCg) of glucose infusion to maintain euglycemia during hyperinsulinemic-euglycemic clamp] and plasma total (TotalG), acylated (AG) and Unacylated ghrelin (UnAG). Plasma pro-inflammatory tumor necrosis factor alpha (TNFα) and anti-inflammatory interleukin-10 (IL-10) were also measured since changes in inflammation may contribute to UnAG activities.

RESULTS

CR reduced BMI and increased insulin sensitivity (p < 0.05). TotalG and UnAG but not AG increased in CR but not in Control (p < 0.05). Il-10 and IL-10/TNFα ratio also increased in CR (p < 0.05). Changes in UnAG were positively associated with changes in AUCg in all subjects (n = 20; p < 0.01) also after adjustment for treatment and changes in BMI and cytokines.

CONCLUSIONS

Caloric restriction modifies circulating ghrelin profile with selective increase in unacylated hormone in obese individuals. The current study supports the hypothesis that higher unacylated ghrelin contributes to improvements in insulin sensitivity following diet-induced weight loss in human obesity.

The therapeutic potential of C-C chemokine receptor antagonists in nonalcoholic steatohepatitis

Pooled prevalence of nonalcoholic fatty liver disease (NAFLD) globally is about 25%. Nonalcoholic steatohepatitis (NASH) with advanced fibrosis has been linked with substantial morbidity and mortality, without having to-date any licensed treatment. C-C chemokine receptor (CCR) antagonists have been investigated as candidates for the treatment of NASH. Inhibition of CCR2 is expected to mitigate hepatic inflammation, through reducing the activation of Kupffer cells, as well as the infiltration of monocytes and macrophages into the liver. Inhibition of CCR5 is expected to mitigate hepatic fibrogenesis, through impairing the activation of hepatic stellate cells, as well as to mitigate hepatic inflammation, through impairing the activation of Kupffer cells and macrophages. Cenicriviroc (CVC) is the first in class, dual inhibitor of CCR2 and CCR5. After exhibiting favorable results in animal models, CVC was shown to be beneficial in NASH patients with more severe fibrosis at a phase 2b trial (CENTAUR) and is currently at a phase 3 clinical trial (AURORA). Apart from CVC, other CCR5 mono-antagonists, such as maraviroc, are under evaluation in clinical trials with human immunodeficiency virus patients with NAFLD. The aim of this review was to summarize existing evidence on CVC and other CCR antagonists in NASH patients, primarily focusing on their clinical efficacy and safety.

Obesity as a risk factor for COVID-19: an overview

The current coronavirus disease-2019 (COVID-19) pandemic presents a huge challenge for health-care systems worldwide. Many different risk factors are associated with disease severity, such as older age, diabetes, hypertension, and most recently obesity. The incidence of obesity has been on the rise for the past 25 years, reaching over 2 billion people throughout the world, and obesity itself could be considered a pandemic. In this review, we summarize aspects involved with obesity, such as changes in the immune response, nutritional factors, physiological factors, and the gut-lung axis, that impact the viral response and the COVID-19 prognosis.

Polymorphisms in miRNA binding sites involved in metabolic diseases in mice and humans

Type 2 diabetes and obesity are well-studied metabolic diseases, which are based on genetic and epigenetic alterations in combination with an obesogenic lifestyle. The aim of this study was to test whether SNPs in miRNA-mRNA binding sites that potentially disrupt binding, elevate the expression of miRNA targets, which participate in the development of metabolic diseases. A computational approach was developed that integrates transcriptomics, linkage analysis, miRNA-target prediction data, and sequence information of a mouse model of obesity and diabetes. A statistical analysis demonstrated a significant enrichment of 566 genes for a location in obesity- and diabetes-related QTL. They are expressed at higher levels in metabolically relevant tissues presumably due to altered miRNA-mRNA binding sites. Of these, 51 genes harbor conserved and impaired miRNA-mRNA-interactions in human. Among these, 38 genes have been associated to metabolic diseases according to the phenotypes of corresponding knockout mice or other results described in the literature. The remaining 13 genes (e.g. Jrk, Megf9, Slfn8 and Tmem132e) could be interesting candidates and will be investigated in the future.

Metabolomics as an Approach to Characterise the Contrasting Roles of CCR5 in the Presence and Absence of Disease

Chemokine receptors such as C-C chemokine receptor 5 (CCR5) are activated through interaction with their ligands and are well known for their role in chemotaxis and signal transduction. While serving these roles, cellular responses are effected, hence the immune function of these molecules is established. Given the role of CCR5 in immune function and that the immune and metabolic systems are interlinked, subsequent immune-directed changes should be measurable at a metabolic level. Numerous investigations have reported on metabolic changes associated with CCR5 status in the presence of disease, so as to understand whether specific CCR5 genotypes, frequency and/or levels offer protection to the host or not. However, these metabolic changes were recorded using older conventional techniques. Depending on certain factors such as the disease model, the geography of the samples and/or the ethnic group under study, the role of CCR5 in disease differs. In addition, little is known about CCR5's role in the absence of an enhanced inflammatory state, such as when infection persists. Metabolomics is defined as the study of metabolites and informs on metabolic changes within living organisms as induced by various stimuli, such as the interaction of CCR5 with its ligand. Since metabolomics reflects the underlying biochemical activity and state of cells/tissues, this review proposes it as a tool to clarify the contrasting roles of CCR5.

A Novel Antidiabetic Monomers Combination Alleviates Insulin Resistance Through Bacteria-Cometabolism-Inflammation Responses

The present study sought to examine the therapeutic effect of a novel antidiabetic monomer combination (AMC) in treating type 2 diabetes mellitus (T2DM); while also elucidating the potential functional mechanism. Male C57BL/6J mice were fed a high-fat diet (HFD) for 12 weeks to establish T2DM. The AMC group showed significant reduction in weight, fasting blood glucose (FBG), serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C), and experienced reduced insulin resistance based on oral glucose tolerance testing (OGTT) and hyperinsulinemic-euglycemic clamp testing (“gold standard” for determining in vivo insulin sensitivity). Further, AMC restored the altered intestinal flora by increasing the abundance of the beneficial bacteria Akkermansia, and decreasing the number of harmful bacteria, including Bacteroides, Odoribacter, Prevotella 9, Alistipes, and Parabacteroides. Components of the host-microbial metabolome were also significantly changed in the AMC group compared to the HFD group, including hydroxyphenyllactic acid, palmitoleic acid, dodecanoic acid, linoleic acid, and erucic acid. Furthermore, AMC was found to inhibit inflammation and suppress signaling pathways related to insulin resistance. Lastly, spearman correlation analysis revealed relationships between altered microbial community and co-metabolite levels, co-metabolites and inflammatory cytokines. Hence, the potential mechanism responsible for AMC-mediated alleviation of insulin resistance was suggested to be involved in modulation of bacteria-cometabolism-inflammation responses.

Research update on the association between SFRP5, an anti-inflammatory adipokine, with obesity, type 2 diabetes mellitus and coronary heart disease

Secreted frizzled-related protein 5 (SFRP5), an anti-inflammatory adipokine secreted by adipocytes, has been demonstrated to exert its anti-inflammatory effect via antagonizing the non-canonical wingless-type family member 5A (WNT5A) signalling pathways. The WNT5A protein, as a potent pro-inflammatory signalling molecule, is strongly involved in a variety of inflammatory disorders such as obesity, type 2 diabetes mellitus (T2DM) and atherosclerosis. In this review, we systematically outlined the current understanding on the roles of SFRP5 in the pathogenesis of three inflammatory diseases including obesity, T2DM and coronary heart disease (CHD). Our review might stimulate future research using SFRP5 as a promising novel therapeutic target for the treatment of obesity, T2DM and CHD.

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.

Chemokines and their association with body mass index among healthy Saudis

Obesity is a chronic disorder that is associated with body mass index (BMI) of greater or equal to 30 kg/m2. The prevalence of obesity in the Kingdom of Saudi Arabia (KSA) is increasing at an alarming rate and is expected to reach 41% in men and up to 78% in women by 2022. Since chemokines are associated with involuntary weight loss, the objective of this study was to elucidate their association with BMI among Saudis. A questionnaire was used to collect information about diet, health conditions, and demographics from 15 men and 16 women who participated in the study. BMI was calculated based on clinical measurements and participants were classified according to their BMI category as: normal, underweight, overweight, or obese. Serum samples were collected for a multiplex assay using the Human Chemokine Magnetic 30-plex panel. The serum concentration of either the monokine induced by gamma interferon (MIG) or the CXC-motif chemokine ligand 9 (CXCL-9) was significantly increased in obese men (P = 0.0194) and women (P = 0.043) as compared to underweight men and women, respectively. However, the serum levels of other chemokines were not significantly different among the groups. We found that MIG levels are differentially regulated in serum, based on individuals' BMI.

Anti-NASH Drug Development Hitches a Lift on PPAR Agonism

Non-alcoholic fatty liver disease (NAFLD) affects one-third of the population worldwide, of which a substantial number of patients suffer from non-alcoholic steatohepatitis (NASH). NASH is a severe condition characterized by steatosis and concomitant liver inflammation and fibrosis, for which no drug is yet available. NAFLD is also generally conceived as the hepatic manifestation of the metabolic syndrome. Consequently, well-established drugs that are indicated for the treatment of type 2 diabetes and hyperlipidemia are thought to exert effects that alleviate the pathological features of NASH. One class of these drugs targets peroxisome proliferator-activated receptors (PPARs), which are nuclear receptors that play a regulatory role in lipid metabolism and inflammation. Therefore, PPARs are now also being investigated as potential anti-NASH druggable targets. In this paper, we review the mechanisms of action and physiological functions of PPARs and discuss the position of the different PPAR agonists in the therapeutic landscape of NASH. We particularly focus on the PPAR agonists currently under evaluation in clinical phase II and III trials. Preclinical strategies and how refinement and optimization may improve PPAR-targeted anti-NASH drug testing are also discussed. Finally, potential caveats related to PPAR agonism in anti-NASH therapy are stipulated.

The antagonist of CXCR1 and CXCR2 protects db/db mice from metabolic diseases through modulating inflammation

Interleukin-8 (IL-8, also named CXCL8) binds to its receptors (CXCR1 and CXCR2) with subsequent recruitment of neutrophils and enhancement of their infiltration into inflamed sites, which exaggerates inflammation in many diseases. Recent studies have proposed that metabolic disorders can be attenuated by counteracting certain inflammatory signal pathways. In this study, we examined whether intervention with G31P, an antagonist of CXCL8, could attenuate tissue inflammation and development of metabolic disorders in db/db mice. The db/m and db/db mice were subcutaneously injected with G31P or equivalent normal saline once a day for 6 wk. The physical and metabolic parameters, glucose tolerance, insulin sensitivity, hepatic lipid accumulation, and inflammation markers were measured. G31P improved hepatic insulin sensitivity by modulating expression of genes related to gluconeogenesis and phosphorylated Akt levels. The expressions of several genes encoding proteins involved in de novo lipogenesis were decreased in G31P-treated db/db mice. Meanwhile, immune cell infiltration and cytokine release were attenuated in db/db mice with G31P treatment. G31P also improved the ratio of proinflammatory M1 and anti-inflammatory M2 macrophages. Furthermore, G31P ameliorates metabolic disturbances via inhibition of CXCR1 and CXCR2 pathways in db/db mice. These data suggest that the selective inhibition of CXC chemokines may have therapeutic effects on symptoms associated with obesity and diabetes.

Impact of Glucoraphanin-Mediated Activation of Nrf2 on Non-Alcoholic Fatty Liver Disease with a Focus on Mitochondrial Dysfunction

Non-alcoholic fatty liver disease (NAFLD) is a common disease in Western nations and ranges in severity from steatosis to steatohepatitis (NASH). NAFLD is a genetic-environmental-metabolic stress-related disease of unclear pathogenesis. NAFLD is triggered by caloric overconsumption and physical inactivity, which lead to insulin resistance and oxidative stress. A growing body of evidence indicates that mitochondrial dysfunction plays a critical role in the pathogenesis of NAFLD. Mitochondrial dysfunction not only promotes fat accumulation, but also leads to generation of reactive oxygen species (ROS) and lipid peroxidation, resulting in oxidative stress in hepatocytes. Nuclear factor erythroid 2-related factor 2 (Nrf2) is an important modulator of antioxidant signaling that serves as a primary cellular defense against the cytotoxic effects of oxidative stress. The pharmacological induction of Nrf2 ameliorates obesity-associated insulin resistance and NAFLD in a mouse model. Sulforaphane and its precursor glucoraphanin are derived from broccoli sprouts and are the most potent natural Nrf2 inducers—they may protect mitochondrial function, thus suppressing the development of NASH. In this review, we briefly describe the role of mitochondrial dysfunction in the pathogenesis of NASH and the effects of glucoraphanin on its development.

Polydatin Inhibits Adipose Tissue Inflammation and Ameliorates Lipid Metabolism in High-Fat-Fed Mice

Polydatin (PD), an active component of Chinese herbs, is reported to have many biological functions, such as cardioprotective actions, anti-inflammatory activities, and antitumor effects. In this study, we investigated the effects of PD on body weight control, glucose and lipid metabolic regulation, and anti-inflammation in a high-fat-diet- (HFD-) induced obese mice model. After treatment of PD (100 mg/kg/d for 4 weeks), HFD mice reduced body weight, retroperitoneal fat mass, and adipose cell sizes; significantly lowered serum total cholesterol triglyceride (TG) and low-density lipoprotein (LDL) levels; and increased high-density lipoprotein (HDL) levels compared with the HFD control mice. Further studies showed that PD downregulated the mRNA and protein expressions of peroxisome proliferator-activated receptor gamma (PPARγ), a transcription factor involving in the regulation of adipocyte differentiation, in the retroperitoneal fat of HFD mice. Additionally, PD significantly upregulated the mRNA and protein expressions of leptin, an adipocyte-derived anorexic hormone that regulates food intake and energy expenditure, in the adipose tissues of HFD mice. Moreover, PD reduced the expression levels of monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-alpha (TNF-α) in the retroperitoneal and epididymal tissues of HFD mice, suggesting that PD prevented adipose tissue inflammation. In conclusion, PD may serve as a pharmaceutic candidate for obesity-related lipid metabolism, anti-inflammation, and body weight loss.

Differential Effects of Alternate-Day Fasting Versus Daily Calorie Restriction on Insulin Resistance

OBJECTIVE

This study compared the effects of alternate-day fasting (ADF) with those of daily calorie restriction (CR) on body weight and glucoregulatory factors in adults with overweight or obesity and insulin resistance.

METHODS

This secondary analysis examined the data of insulin-resistant individuals (n = 43) who participated in a 12-month study that compared ADF (25% energy needs on "fast days"; 125% energy needs on alternating "feast days") with CR (75% energy needs every day) and a control group regimen.

RESULTS

In insulin-resistant participants, weight loss was not different between ADF (-8% ± 2%) and CR (-6% ± 1%) by month 12, relative to controls (P < 0.0001). Fat mass and BMI decreased (P < 0.05) similarly from ADF and CR. ADF produced greater decreases (P < 0.05) in fasting insulin (-52% ± 9%) and insulin resistance (-53% ± 9%) compared with CR (-14% ± 9%; -17% ± 11%) and the control regimen by month 12. Lean mass, visceral fat mass, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, blood pressure, C-reactive protein, tumor necrosis factor α, and interleukin 6 values remained unchanged.

CONCLUSIONS

These findings suggest that ADF may produce greater reductions in fasting insulin and insulin resistance compared with CR in insulin-resistant participants despite similar decreases in body weight.

TNF-α in Combination with Palmitate Enhances IL-8 Production via The MyD88- Independent TLR4 Signaling Pathway: Potential Relevance to Metabolic Inflammation

Elevated levels of IL-8 (CXCL8) in obesity have been linked with insulin resistance and type 2 diabetes (T2D). The mechanisms that lead to the profound production of IL-8 in obesity remains to be understood. TNF-α and saturated free fatty acids (FFAs) are increased in obese humans and correlate with insulin resistance. Hence, we sought to investigate whether the cooccurrence of TNF-α and FFAs led to increase the production of IL-8 by human monocytes. We found that co-stimulation of human monocytes with palmitate and TNF-α led to increased IL-8 production as compared to those stimulated with palmitate or TNF-α alone. The synergistic production of IL-8 by TNF-α/palmitate was suppressed by neutralizing anti- Toll like receptor 4 (TLR4) antibody and by genetic silencing of TLR4. Both MyD88-deficient and MyD88-competent cells responded comparably to TNF-α/Palmitate. However, TIR-domain-containing adapter-inducing interferon (TRIF) inhibition or interferon regulatory transcription factor 3 (IRF3) knockdown partly blocked the synergistic production of IL-8. Our human data show that increased adipose tissue TNF-α expression correlated positively with IL-8 expression (r = 0.49, P = 0.001). IL-8 and TNF-α correlated positively with macrophage markers including CD68, CD163 and CD86 in adipose tissue. These findings suggest that the signaling cross-talk between saturated fatty acid palmitate and TNF-α may be a key driver in obesity-associated chronic inflammation via an excessive production of IL-8.

Macrophage Rewiring by Nutrient Associated PI3K Dependent Pathways

Class 1 Phosphoinositide-3-Kinases (PI3Ks) have been widely studied and mediate essential roles in cellular proliferation, chemotaxis, insulin sensitivity, and immunity. Here, we provide a comprehensive overview of how macrophage expressed PI3Ks and their downstream pathways orchestrate responses to metabolic stimuli and nutrients, polarizing macrophages, shaping their cellular identity and function. Particular emphasis will be given to adipose tissue macrophages, crucial players of insulin resistance and chronic metabolically triggered inflammation during obesity. An understanding of PI3K dependent wiring of macrophage responses is important as this is involved in various diseases ranging from obesity, type 2 diabetes to chronic inflammatory disease.

Noninvasive diagnostic criteria for nonalcoholic steatohepatitis based on gene expression levels in peripheral blood mononuclear cells

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) consists of nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH); the latter progresses to liver cirrhosis and hepatocellular carcinoma. Discriminating NASH from NAFL typically involves liver biopsy. The mechanism of NASH progression is unclear but may involve immunological pathways. In this study, we examined expression levels of cytokine- and chemokine-encoding genes in peripheral blood mononuclear cells (PBMCs) from NAFLD patients and established immunological criteria for discriminating NASH from NAFL.

METHODS

PBMCs were obtained from 54 patients diagnosed histologically with NAFLD (NAFL, 18; NASH, 36). mRNA was extracted from PBMCs, and expression levels of cytokine- and chemokine-encoding genes were determined by quantitative real-time PCR. Statistical analysis was performed by nonparametric test.

RESULTS

Expression levels of interferon (IFN)γ, interleukin (IL)2, IL15, C-C-motif chemokine ligand (CCL)2, IL10, and C-X-C-motif chemokine ligand (CXCL)11 were significantly upregulated in NASH patients compared with NAFL patients. Moreover, their expression levels were positively correlated with the degree of ballooning of hepatocytes but not of steatosis or lobular inflammation. We focused on those encoding IL10, IFNγ, and CCL2, and developed a scoring system to discriminate NASH from NAFL. The discriminatory power of the criteria was validated in an independent cohort.

CONCLUSIONS

Expression levels of the cytokine- and chemokine-encoding genes in PBMCs were positively correlated with ballooning, suggesting their utility for the diagnosis of NASH. The data indicate that peripheral as well as intrahepatic immunity is involved in the progression of NASH. Our findings afford new insight into immunological mechanisms of NASH and will facilitate its noninvasive diagnosis.

Identification of Novel CXCL12 Genetic Polymorphisms Associated with Type 2 Diabetes Mellitus: A Chinese Sib-Pair Study

Aims: To discover possible relationships between CXCL12 single nucleotide polymorphisms (SNPs) and type 2 diabetes mellitus (T2DM) and its risk factors. Methods: The present sib-pair study was conducted in a rural community of Beijing, China. SNPs rs2297630, rs1746048, and rs1801157 located within or nearby the CXCL12 gene were genotyped using the allele-specific polymerase chain reaction method. Haseman-Elston regression was used to investigate linkages between these SNPs and T2DM. A generalized estimating equation logistic regression model was used to discover associations between the SNPs, T2DM, and its risk factors. Results: A total of 3171 participants were recruited, comprising 2277 sib pairs. After Bonferroni correction (α = 0.016), rs2297630 was found to be significantly linked to (p = 0.003) and associated with T2DM (AA vs. GG/GA: OR = 2.26, 95% CI: 1.31-3.88, p = 0.003). There were interactions between rs2297630 and dyslipidemia (p < 0.001) and between rs1746048 and hypertension (p = 0.011). Compared to dyslipidemia-free subjects with rs2297630 GG/GA genotypes, dyslipidemia patients with rs2297630 AA had a higher risk of T2DM (OR = 4.15, 95% CI: 2.24-7.67, p < 0.001). Compared to hypertension-free subjects with rs1746048 CC genotypes, hypertension-free subjects with rs1746048 CT/TT had a decreased risk of T2DM (OR = 0.77, 95% CI: 0.60-0.99, p = 0.045). Conclusions: A novel linkage and association was found between rs2297630 and T2DM. Moreover, novel interactions were found between rs2297630 and dyslipidemia as well as rs1746048 and hypertension. These findings will help identify individuals at higher risk of developing T2DM.

Preclinical study of the long-range safety and anti-inflammatory effects of high-dose oral meglumine

Meglumine is a methylamino derivative of sorbitol that is an approved drug excipient. Recent preclinical studies suggest that administration of high-dose oral meglumine can exert beneficial medicinal effects to treat diabetes, obesity, and fatty liver disease (NAFLD/nonalcoholic steatohepatitis [NASH]). Here we address gaps in knowledge about the pharmacology and toxicology of this substance administered at high concentrations to explore its medicinal potential. We observed that high-dose meglumine limited secretion of proinflammatory cytokines and cell adhesion molecules from activated human THP-1 or murine RAW264.7 monocytes. Preclinical pharmacokinetic analysis in Swiss mice confirmed that meglumine was orally available. Informed by this data, oral doses of 18 to 75 mM meglumine were administered ad libitum in the drinking water of Sprague-Dawley rats and two cohorts of C57BL/6 mice housed in different vivariums. In a 32-week study, urinary isoprostane levels trended lower in subjects consistent with the possibility of anti-inflammatory effects. In full lifespan studies, there was no detrimental effect on longevity. Heart function evaluated in C57BL/6 mice using an established noninvasive cardiac imaging system showed no detrimental effects on ejection fraction, fractional shortening, left ventricle function or volume, and cardiac output in mice up to 15-month old, with a potential positive trend in heart function noted in elderly mice consistent with earlier reported benefits on muscle stamina. Finally, in a transgenic model of inflammation-associated skin carcinogenesis, the incidence, number, and growth of skin tumors trended lower in subjects receiving meglumine. Overall, the evidence obtained illustrating the long-range safety of high-dose oral meglumine support the rationale for its evaluation as a low-cost modality to limit diabetes, hypertriglyceridemia, and NAFLD/NASH.

Transcriptomics Analysis Reveals New Insights into the Roles of Notch1 Signaling on Macrophage Polarization

Naïve macrophages (Mφ) polarize in response to various environmental cues to a spectrum of cells that have distinct biological functions. The extreme ends of the spectrum are classified as M1 and M2 macrophages. Previously, we demonstrated that Notch1 deficiency promotes Tgf-β2 dependent M2-polarization in a mouse model of abdominal aortic aneurysm. The present studies aimed to characterize the unique set of genes regulated by Notch1 signaling in macrophage polarization. Bone marrow derived macrophages isolated from WT or Notch1+/- mice (n = 12) were differentiated to Mφ, M1 or M2-phenotypes by 24 h exposure to vehicle, LPS/IFN-γ or IL4/IL13 respectively and total RNA was subjected to RNA-Sequencing (n = 3). Bioinformatics analyses demonstrated that Notch1 haploinsufficiency downregulated the expression of 262 genes at baseline level, 307 genes with LPS/IFN-γ and 254 genes with IL4/IL13 treatment. Among these, the most unique genes downregulated by Notch1 haploinsufficiency included fibromodulin (Fmod), caspase-4, Has1, Col1a1, Alpl and Igf. Pathway analysis demonstrated that extracellular matrix, macrophage polarization and osteogenesis were the major pathways affected by Notch1 haploinsufficiency. Gain and loss-of-function studies established a strong correlation between Notch1 haploinsufficiency and Fmod in regulating Tgf-β signaling. Collectively, our studies suggest that Notch1 haploinsufficiency increases M2 polarization through these newly identified genes.

A dual farnesoid X receptor/soluble epoxide hydrolase modulator treats non-alcoholic steatohepatitis in mice

Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are the most prevalent metabolic liver disorders and a serious global health burden. NAFLD/NASH pathogenesis and progression are highly multi-factorial and likely demand a combination of multiple mechanisms to provide a more effective treatment. We have developed a dual farnesoid X receptor agonist (FXRA)/soluble epoxide hydrolase inhibitor (sEHi) to simultaneously address two validated and complementary modes of action in NASH treatment. Here we report the in vivo profiling for this FXRA/sEHi in toxin- and diet-induced rodent NASH models. In streptozotocin-induced NASH as a proof-of-concept study, the experimental FXRA/sEHi drug robustly prevented hepatic steatosis and fibrosis, and improved lipid homeostasis as well as biochemical markers of liver health. In methionine-choline-deficient high-fat diet-induced NASH, FXRA/sEHi treatment reduced hepatic steatosis and fibrosis to levels similar to healthy animals and demonstrated anti-inflammatory activity confirming that dual FXRA/sEHi modulation produces a triad of complementary anti-NASH effects. Our results validate dual FXRA/sEHi modulation as an effective therapeutic strategy to treat NASH and advocates for a combinational drug therapeutic approach for multifactorial liver diseases.

Elafibranor restricts lipogenic and inflammatory responses in a human skin stem cell-derived model of NASH

Non-alcoholic steatohepatitis (NASH) is characterized by hepatocellular steatosis with concomitant hepatic inflammation. Despite its pandemic proportions, no anti-NASH drugs have been approved yet. This is partially because drug development is decelerated due to the lack of adequate tools to assess the efficacy of potential new drug candidates. The present study describes the development and application of a new preclinical model for NASH using hepatic cells generated from human skin-derived precursors. Exposure of these cells to lipogenic (insulin, glucose, fatty acids) and pro-inflammatory factors (IL-1β, TNF-α, TGF-β) resulted in a characteristic NASH response, as indicated by intracellular lipid accumulation, modulation of NASH-specific gene expression, increased caspase-3/7 activity and the expression and/or secretion of inflammatory markers, including CCL2, CCL5, CCL7, CCL8, CXCL5, CXCL8, IL1a, IL6 and IL11. The human relevance of the proposed NASH model was verified by transcriptomics analyses that revealed commonly modulated genes and the identification of the same gene classes between the in vitro system and patients suffering from NASH. The application potential of this in vitro model was demonstrated by testing elafibranor, a promising anti-NASH compound currently under clinical phase III trial evaluation. Elafibranor attenuated in vitro key features of NASH, and dramatically lowered lipid load as well as the expression and secretion of inflammatory chemokines, which in vivo are responsible for the recruitment of immune cells. This reduction in inflammatory response was NFκB-mediated. In summary, this human-relevant, in vitro system proved to be a sensitive testing tool for the investigation of novel anti-NASH compounds.

Analysis of Inflammatory Gene Expression Profile of Peripheral Blood Leukocytes in Type 2 Diabetes

The pathophysiology of type 2 diabetes (T2DM) is associated with perturbation of innate immune response. Several studies indicated alteration of pro-inflammatory and anti-inflammatory cytokines, chemokines and other mediators of innate immune response in T2DM. This study was designed to perform quantitative PCR-based expression profiling of genes involved in inflammation (i.e. CASP1, CASP5, CCL5, CXC11, CCR5, NF-Κb, IL-4, PPARG and PGC1α) in peripheral blood leukocytes of T2DM patients. The T2DM patients are often prescribed with metformin and insulin while metformin has also been reported to possess anti-inflammatory activity. To address the question whether metformin exerts any effect on inflammatory mediators in bloodstream, human subjects in this study were divided into four groups on the basis of medication they were taking during last 6 month. These groups included NT-T2DM (T2DM patients not taking medication, n = 34), Met-T2DM (T2DM patients taking metformin, n = 33), INS-T2DM (T2DM patients taking insulin, n = 15) and NGT (normoglycemic subjects, n = 34) groups. Differential expression of gene transcripts at a cutoff of fourfold was considered significant. In the NT-T2DM group, transcripts of inflammation-related genes (i.e. CASP1, CASP5, CCL5, CCR5 and NF-kB) were up-regulated while transcripts of PPARG and PGC1α genes were down-regulated compared to NGT group. On the other hand, down-regulation of CASP1, CASP5, CCL5, CCR5 and NF-kB transcripts was evident in Met-T2DM and INS-T2DM groups when compared to the NT-T2DM group. The Met-T2DM group and INS-T2DM group showed a significant difference in the transcript level of CASP1 and CCL5 which are more down-regulated in the Met-T2DM group compared to INS-T2DM group. These findings indicated that (a) in T2DM, expression of inflammation-related genes is up-regulated and (b) anti-inflammatory activity of metformin appears to be independent of its anti-hyperglycemic activity.

Chemokine (C-C motif) ligand 2 gene ablation protects low-density lipoprotein and paraoxonase-1 double deficient mice from liver injury, oxidative stress and inflammation

The risk of non-alcoholic fatty liver disease increases with obesity. Vulnerability to oxidative stress and/or inflammation represents a crucial step in non-alcoholic fatty liver disease progression through abnormal metabolic responses. In this study, we investigated the role of CCL2 gene ablation in mice that were double deficient in low density lipoprotein receptor and in paraoxonase-1. Mass spectrometry methods were used to assess the liver metabolic response in mice fed either regular chow or a high-fat diet. Dietary fat caused liver steatosis, oxidative stress and the accumulation of pro-inflammatory macrophages in the livers of double deficient mice. We observed alterations in energy metabolism-related pathways and in metabolites associated with the methionine cycle and the glutathione reduction pathway. This metabolic response was associated with impaired autophagy. Conversely, when we established CCL2 deficiency, histologic features of fatty liver disease were abrogated, hepatic liver oxidative stress decreased, and anti-inflammatory macrophage marker expression levels increased. These changes were associated with the normalization of metabolic disturbances and increased lysosome-associated membrane protein 2, expression, which suggests enhanced chaperone-mediated autophagy. This study demonstrates that CCL2 is a key molecule for the development of metabolic and histological alterations in the liver of mice sensitive to the development of hyperlipidemia and hepatic steatosis, a finding with potential to identify new therapeutic targets in liver diseases.

Systems Genomics of Thigh Adipose Tissue From Asian Indian Type-2 Diabetics Revealed Distinct Protein Interaction Hubs

We performed a systematic analysis of genes implicated in thigh subcutaneous adipose tissue of Asian Indian Type 2 Diabetes Mellitus (AIT2DM) and created a phenome-interactome network. This analysis was performed on 60 subjects specific to limb thigh fat by integrating phenotypic traits and similarity scores associated with AIT2DM. Using a phenotypic attribute, a contextual neighbor was identified across all the traits, viz. body mass index (BMI) statistics, adipocyte size, lipid parameters, homeostatic model assessment- insulin resistance (HOMA-IR), HOMA-ß. In this work, we have attempted to characterize transcription signatures using the phenome-interactome maps where each of the traits under study including the intermediary phenotypes has a distinct set of genes forming the hubs. Furthermore, we have identified various clinical, biochemical, and radiological parameters which show significant correlation with distinct hubs. We observed a number of novel pathways and genes including those that are non-coding RNAs implicated in AIT2DM.We showed that they appear to be associated with pathways, viz. tyrosine kinase JAK2, NOTCH thereby recruiting signaling molecules such as STAT5 and Src family kinases on the cell surface regulated them and our analyses comprising significant hubs suggest that thigh subcutaneous adipose tissue plays a role in pathophysiology of AIT2DM.

ER-stress regulates macrophage polarization through pancreatic EIF-2alpha kinase

During the process of NAFLD progression, ER-stress is activated in macrophages and induces the pro-inflammatory polarization of macrophage. As one of the three ER membrane resident proteins, pancreatic eIF-2alpha kinase (PERK) plays an important role in ER stress, but its participation in macrophage polarization is largely unknown. In this study, we found that the PA mediated ER-stress activation could induce M1-type polarization in macrophages, and this phenotype polarization could be inhibited by ER-stress inhibitor 4-PBA as well as GSK2656157, an inhibitor of PERK. Moreover, the knockdown of PERK altered the STAT1 and STAT6 pathways in macrophages, which then led to the M1-to-M2 phenotypic shift. In summary, we found that PERK could regulate the phenotypic polarization of macrophages. This finding may provide new insight into the suppression of pathological progression of fatty liver or liver ischemia reperfusion injury induced by M1-type macrophages.

Genomics of lipid-laden human hepatocyte cultures enables drug target screening for the treatment of non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a major health burden in need for new medication. To identify potential drug targets a genomic study was performed in lipid-laden primary human hepatocyte (PHH) and human hepatoma cell cultures.

METHODS

PHH, HuH7 and HepG2 hepatoma cell cultures were treated with lipids and/or TNFα. Intracellular lipid load was quantified with the ORO assay. The Affymetrix HG-U133+ array system was employed to perform transcriptome analysis. The lipid droplet (LD) growth and fusion was determined by fluorescence microscopy. LD associated proteins were imaged by confocal immunofluorescence microscopy and confirmed by Western immunoblotting. Bioinformatics defined perturbed metabolic pathways.

RESULTS

Whole genome expression profiling identified 227, 1031 and 571 significant regulated genes. Likewise, the combined lipid and TNFα treatment of PHH, HuH7 and HepG2 cell cultures revealed 154, 1238 and 278 differentially expressed genes. Although genomic responses differed among in-vitro systems, commonalities were ascertained by filtering the data for LD associated gene regulations. Among others the LD-growth and fusion associated cell death inducing DFFA like effector C (CIDEC), perilipins (PLIN2, PLIN3), the synaptosome-associated-protein 23 and the vesicle associated membrane protein 3 were strongly up-regulated. Likewise, the PPAR targets pyruvate-dehydrogenase-kinase-4 and angiopoietin-like-4 were up-regulated as was hypoxia-inducible lipid droplet-associated (HILPDA), flotilin and FGF21. Their inhibition ameliorates triglyceride and cholesterol accumulation. TNFα treatment elicited strong induction of the chemokine CXCL8, the kinases MAP3K8, MAP4K4 and negative regulators of cytokine signaling, i.e. SOCS2&SOCS3. Live cell imaging of DsRED calreticulin plasmid transfected HuH7 cells permitted an assessment of LD growth and fusion and confocal immunofluorescence microscopy evidenced induced LD-associated PLIN2, CIDEC, HIF1α, HILPDA, JAK1, PDK4 and ROCK2 expression. Notwithstanding, CPT1A protein was repressed to protect mitochondria from lipid overload. Pharmacological inhibition of the GTPase-dynamin and the fatty acid transporter-2 reduced lipid uptake by 28.5 and 35%, respectively. Finally, a comparisons of in-vitro/NAFLD patient biopsy findings confirmed common gene regulations thus demonstrating clinical relevance.

CONCLUSION

The genomics of fat-laden hepatocytes revealed LD-associated gene regulations and perturbed metabolic pathways. Immunofluorescence microscopy confirmed expression of coded proteins to provide a rationale for therapeutic intervention strategies. Collectively, the in-vitro system permits testing of drug candidates.

Chemokine gene polymorphisms association with increased risk of type 2 diabetes mellitus in Tatar ethnic group, Russia

Recent studies have shown that chemokines play an important role in the development of chronic inflammation in adipose tissue, obesity pathogenesis, glucose intolerance and type 2 diabetes. It has also been revealed that some SNPs in chemokine genes are associated with obesity, insulin resistance, type 2 diabetes and diabetes complications in different ethnic groups. The aim of this study was to determine the associations between SNPs in chemokine genes and type 2 diabetes in participants of Tatar ethnic group, living in Bashkortostan. Case-control and cross-sectional study were included in our study design. Five SNPs were genotyped in 440 type 2 diabetes (160 men and 280 women), 58.8 ± 9.2 years old (mean ± SD), BMI 29.3 ± 3.9 kg/m² (mean ± SD) patients of Tatar ethnicity, and a control group of 500 Tatars (180 men and 320 women), 55.2 ± 11.6 years old (mean ± SD), BMI 25.9 ± 4.3 kg/m² (mean ± SD). The SNPs rs6749704 in CCL20 [odds ratio (OR) = 2.77 (95% CI 1.81-4.25), р = 0.0001], rs2107538 in CCL5 [odds ratio (OR) = 1.80 (95% CI 1.46-2.22), p = 0.0001] were significantly associated with type 2 diabetes. Regression analysis revealed that rs1696941 in CCL11 was associated with the onset age and duration of type 2 diabetes as well as with HbA_1c level (p = 0.034, p = 0.036 and p = 0.0054, respectively). The SNPs rs223828 in CCL17 and rs6749704 in CCL20 were correlated with obesity as estimated by BMI (p = 0.0004, p = 0.029, respectively). Rs223828 in CCL17 revealed the association with postprandial glucose level (p = 0.024) and HbA_1c (p = 0.008). These data demonstrate that variants of chemokine genes are associated with type 2 diabetes and obesity of Tatar ethnic group inhabiting Bashkortostan Republic. Novel associations of the polymorphic loci in CCL20 (rs6749704) and CCL5 (rs2107538) genes with type 2 diabetes had been identified as a result of the conducted research.

A Network Biology Approach for Assessing the Role of Pathologic Adipose Tissues in Insulin Resistance Using Meta-analysis of Microarray Datasets

Background

The role of adipose tissue in Insulin resistance (IR) and Type 2 Diabetes (T2D) has well been received in the biomedical community; being a precursor of T2D, identification of the molecular basis of IR is therefore, vital to elucidate T2D- pathogenesis and meta-analysis of previously conducted microarray studies provides an inexpensive approach to achieve this end.

Methods

In this study, we have carried out a statistical meta-analysis of 157 microarray datasets from five independent studies and identified a meta-signature of 1,511 genes; their functional meaning was elucidated by integrated pathways-analysis. Further, a protein-protein interaction network was constructed and key genes along with their high confidence transcriptional- and epigenetic-mediators were identified using a network biology approach.

Results

Various inflammation- and immune system-related pathways such as TGF-β signaling, IL7 signaling, Neutrophil degranulation, and Chemokine signaling etc. were enriched in sick adipose tissues; identified transcription factors, and microRNAs were also found to regulate processes relevant to IR/T2D pathophysiology.

Conclusion

This study endorses the development of effective bioinformatics workflow and further grants an indication for the acceptance of adiposopathy as the root mechanistic pathology that poses risk for development of type 2 diabetes; concept of adipospathy in place of metabolic syndrome will open the possibility to design drugs, those will ameliorate adipose functions and hence proved to be more effective against Type 2 Diabetes.

CXC Motif Ligand 16 Promotes Nonalcoholic Fatty Liver Disease Progression via Hepatocyte-Stellate Cell Crosstalk

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) is a focus of attention because of its prevalence. CXC motif ligand 16 (CXCL16) has been studied in inflammatory and metabolic diseases.

OBJECTIVE

To investigate the role of CXCL16 in steatosis and fibrosis in patients with NAFLD.

DESIGN

Liver specimens and sera of patients with NAFLD were collected from 2012 to 2017.

SETTING

Beijing 302 Hospital.

PARTICIPANTS

117 patients with NAFLD and 15 healthy controls.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

The main outcome measures were CXCL16 levels in sera and biopsy specimens of patients with NAFLD.

RESULTS

CXCL16 serum level was markedly elevated in patients with NAFLD, especially in those at the S3 steatosis level according to the steatosis, activity, and fibrosis (SAF) scoring system. The different serum levels of CXCL16 between groups were due to data in patients with A or F scores ≥2, according to the SAF scoring system. CXCL16 accumulated around steatotic hepatocytes in biopsy specimens. In vitro, CXCL16 treatment led to severe steatosis of hepatocytes in the hepatocyte-stellate cell coculture system and suppressed the respiration rate of hepatocytes. Lipogenic gene expression and hepatic stellate cell activation indexes were increased in a CXCL16 overexpression system. In addition, ligands in the Hedgehog pathway cascade were downregulated in hepatocytes.

CONCLUSIONS

CXCL16 was highly expressed in patients with NAFLD, suggesting that it may contribute to steatotic and fibrotic progression. CXCL16 may be a potential noninvasive marker of NAFLD and a future potential therapeutic target to treat NAFLD.

Serum levels of chemokines IP-10, IL-8 and SDF-1 serve as good biomarkers for diabetes-tuberculosis nexus

BACKGROUND

Inflammation has long been identified as an essential component of both Type-2 diabetes and tuberculosis. Chemokines are low molecular weight proteins which play an important role in both inflammation (diabetes) and immunity (tuberculosis).

METHODS

In this study, we measured the serum levels of IP-10, IL-8 and SDF-1 in subjects with Normal Glucose Tolerance (NGT-TB^- = 108; NGT-TB⁺ = 200), Pre-Diabetes (PDM-TB^- = 118; PDM-TB⁺ = 105), Newly Diagnosed Diabetes (NDM-TB^- = 105; NDM-TB⁺ = 63) and Known Diabetes (KDM-TB^- = 131; KDM-TB⁺ = 108), by ELISA. Along with chemokines pro-inflammatory cytokines TNF-ɑ and IL-6 were also measured in these groups.

RESULTS

While IP-10 levels were significantly reduced in TB⁺ subjects in all the sub-groups, IL-8 levels were significantly reduced in NDM-TB⁺ and increased in KDM-TB⁺ subjects. SDF-1 levels were significantly elevated in TB⁺ subjects in all the subgroups, except for KDM-TB⁺.

CONCLUSION

Altered serum chemokine levels can alter anti-TB immunity in diabetes patients and can fuel DM-TB nexus.

Testosterone Levels and Type 2 Diabetes-No Correlation with Age, Differential Predictive Value in Men and Women

Most studies reporting on the association of circulating testosterone levels with type 2 diabetes in men are of cross-sectional design. Reports on the relevance of altered testosterone levels in women are scarce. Here, we evaluate the role of low serum testosterone levels for incident diabetes in men and women in a population setting of 7706 subjects (3896 females). During a mean follow up time of 13.8 years, 7.8% developed type 2 diabetes. Significant correlations of testosterone with high density lipoprotein (HDL)-cholesterol (R = 0.21, p < 0.001), body-mass-index (R = −0.23, p < 0.001), and waist-to-hip-ratio (R = −0.21, p < 0.001) were found in men. No correlation was found with age in men; in women, the correlation was negligible (R = 0.04, p = 0.012). In men, low testosterone levels predicted high risk of type 2 diabetes, while in women this relationship was opposite. Men with low testosterone levels showed increased risk of future diabetes (hazard ratio (HR) 2.66, 95% confidence interval (CI) 1.91–3.72, p < 0.001 in basic model; HR 1.56 95%, CI 1.10–2.21, p = 0.003). In women, low testosterone levels indicated lower risk with (HR 0.53, 95% CI 0.37–0.77, p = 0.003), while the association lost significance in the fully adjusted model (HR 0.72, 95% CI 0.49–1.05, p = 0.09). Low levels of testosterone predicted future diabetes in men. A borderline opposite association was found in women.

IRE1α aggravates ischemia reperfusion injury of fatty liver by regulating phenotypic transformation of kupffer cells

Fatty liver is one of the widely accepted marginal donor for liver transplantation, but is also more sensitive to ischemia and reperfusion injury (IRI) and produces more reactive oxygen species (ROS). Moreover, so far, no effective method has been developed to alleviate it. Endoplasmic reticulum stress (ER-stress) of hepatocyte is associated with the occurrence of fatty liver disease, but ER-stress of kupffer cells (KCs) in fatty liver is not clear at all. This study evaluates whether ER-stress of KCs is activated in fatty liver and accelerate IRI of fatty livers. ER-stress of KCs was activated in fatty liver, especially the IRE1α signal pathway. KCs with activated ER-stress secreted more proinflammatory cytokine to induce its M1-phenotypic shift in fatty liver, resulting in more severe IRI. Also, activated ER-stress of BMDMs in vitro by tunicamycin can induce its pro-inflammatory shift and can be reduced by 4-PBA, an ER-stress inhibitor. Knockdown of IRE1α could regulate the STAT1 and STAT6 pathway of macrophage to inhibit the M1-type polarization and promote M2-phenotypic shift. Furthermore, transfusion of IRE1α-knockdown KCs significantly reduced the liver IRI as well as the ROS of HFD feeding mice. Altogether, these data demonstrated that IRE1α of KCs may be a potential target to reduce the fatty liver associated IRI in liver transplantation.

Glucoraphanin: a broccoli sprout extract that ameliorates obesity-induced inflammation and insulin resistance

Obesity is a low-grade sustained inflammatory state that causes oxidative stress in different metabolic tissues, which leads to insulin resistance and nonalcoholic fatty liver disease (NAFLD). Particularly, obesity-induced metabolic endotoxemia plays an important role in the pathogenesis of insulin resistance and inflammation. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key regulator of antioxidant signaling that serves as a primary cellular defense against the cytotoxic effects of oxidative stress. Pharmacological stimulation of Nrf2 mitigates obesity and insulin resistance in mice; however, Nrf2 activators are not clinically available due to biosafety concerns. A recent study demonstrated that glucoraphanin, a precursor of the Nrf2 activator sulforaphane, ameliorates obesity by enhancing energy expenditure and browning of white adipose tissue, and attenuates obesity-related inflammation and insulin resistance by polarizing M2 macrophages and reducing metabolic endotoxemia. Thus, this review focuses on the efficiency and safety of glucoraphanin in alleviating obesity, insulin resistance, and NAFLD. Abbreviations: ALT, Alanine aminotransferase; AMPK, AMP-activated protein kinase; ATMs, Adipose tissue macrophages; BAT, Brown adipose tissue; CDDO-Im, 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid-imidazolide; CDDO-Me, CDDO-methyl ester; DIO, High-fat-diet-induced obese; FFA, Free fatty acid; FGF, Fibroblast growth factor; GTP, Glutamyl transpeptidase; HFD, High-fat diet; IKKβ, Inhibitor of κB-kinase β; IL, Interleukin; JNK, C-Jun N-terminal kinase; KD, Knockdown; Keap1, Kelch-like ECH-associated protein 1; KO, Knockout; LPS, Lipopolysaccharide; NADPH, Nicotinamide adenine dinucleotide phosphate; NAFLD, Non-alcoholic fatty liver disease; NF-κB, Nuclear factor-κB; Nrf2, Nuclear factor E2-related factor 2; ROS, Reactive oxygen species; T2D, Type 2 diabetes; TLR, Toll-like receptor; TNF, tumor necrosis factor; UCP, Uncoupling protein; WAT, White adipose tissue.

Chemokines in homeostasis and diseases

For the past twenty years, chemokines have emerged as a family of critical mediators of cell migration during immune surveillance, development, inflammation and cancer progression. Chemokines bind to seven transmembrane G protein-coupled receptors (GPCRs) that are expressed by a wide variety of cell types and cause conformational changes in trimeric G proteins that trigger the intracellular signaling pathways necessary for cell movement and activation. Although chemokines have evolved to benefit the host, inappropriate regulation or utilization of these small proteins may contribute to or even cause diseases. Therefore, understanding the role of chemokines and their GPCRs in the complex physiological and diseased microenvironment is important for the identification of novel therapeutic targets. This review introduces the functional array and signals of multiple chemokine GPCRs in guiding leukocyte trafficking as well as their roles in homeostasis, inflammation, immune responses and cancer.

RORα Induces KLF4-Mediated M2 Polarization in the Liver Macrophages that Protect against Nonalcoholic Steatohepatitis

The regulation of M1/M2 polarization in liver macrophages is closely associated with the progression of nonalcoholic steatohepatitis (NASH); however, the mechanism involved in this process remains unclear. Here, we describe the orphan nuclear receptor retinoic-acid-related orphan receptor α (RORα) as a key regulator of M1/M2 polarization in hepatic residential Kupffer cells (KCs) and infiltrated monocyte-derived macrophages. RORα enhanced M2 polarization in KCs by inducing the kruppel-like factor 4. M2 polarization was defective in KCs and bone-marrow-derived macrophages of the myeloid-specific RORα null mice, and these mice were susceptible to HFD-induced NASH. We found that IL-10 played an important role in connecting the function of M2 KCs to lipid accumulation and apoptosis in hepatocytes. Importantly, M2 polarization was controlled by a RORα activator, JC1-40, which improved symptoms of NASH. Our results suggest that the M2-promoting effects of RORα in liver macrophages may provide better therapeutic strategies against NASH.

Inflammatory Cytokine Profiles in Visceral and Subcutaneous Adipose Tissues of Obese Patients Undergoing Bariatric Surgery Reveal Lack of Correlation With Obesity or Diabetes

Population studies have linked insulin resistance to systemic low-grade chronic inflammation and have reported elevated levels of inflammatory cytokines such as TNFα, IL-1β and IL-6, individually or in certain combinations, in adipose tissues or in the serum. We undertook this comprehensive study to simultaneously evaluate the expression of several pro-inflammatory and anti-inflammatory cytokines in serum and in the visceral and subcutaneous adipose tissues from obese patients undergoing bariatric surgery. We observed that several inflammatory cytokines implicated in obesity-associated inflammation showed no significant difference in protein or gene expression between obese patients with or without diabetes and control groups. IL1B gene expression was significantly elevated in the visceral adipose tissues of obese patients, but did not correlate with their diabetes status. Despite the significant increase in IL1B expression in the obese group, a significant proportion of obese patients did not express TNFA, IL1B or IL6 in visceral adipose tissues. Certain inflammatory cytokines showed correlation with the chemokine CCL2 and VEGF-A in visceral adipose tissues. Our findings suggest that the inflammatory cytokine profile in metabolic syndrome is more complex than what is currently perceived and that chronic inflammation in obese patients likely results from incremental contribution from different cytokines and possibly other inflammatory mediators from within and outside the adipose tissues. It is possible that this obesity associated chronic inflammation is not predicted by a single mediator, but rather includes a large spectrum of possible profiles.

•

Visceral and subcutaneous adipose tissues do not express similar pattern of cytokines.

•

VAT and SAT tissues from 30% of the obese patients do not express TNFA, IL6 or IL1B.

•

Protein levels and gene expression do not necessarily correlate in VAT or SAT.

•

The expression pattern of inflammatory mediators may present a larger spectrum than predicted from animal models.

Obesity, type 2 diabetes and cardiometabolic diseases are associated with a low-grade chronic inflammation. Various inflammatory mediators have been shown to mediate this inflammation. In this study we analyzed the expression of many of these inflammatory mediators in the visceral and subcutaneous adipose tissues obtained from patients undergoing bariatric surgery. Our results suggest that the profile of inflammatory mediators expressed in adipose tissue is diverse and varies from one patient to another.

A porcine placental extract prevents steatohepatitis by suppressing activation of macrophages and stellate cells in mice

Nonalcoholic fatty liver disease (NAFLD) is caused by ectopic fat accumulation in the liver. NAFLD is associated with hepatic inflammation and oxidative stress, resulting in nonalcoholic steatohepatitis (NASH) with advanced fibrosis. Placental extracts have been used to treat various chronic diseases due to their antioxidative effect. However, the effects of the extracts on the development of NASH have yet to be elucidated. Here, we demonstrated that supplementation with an oral porcine placental extract (PPE) attenuated lipid accumulation and peroxidation, insulin resistance, inflammatory and stress signaling, and fibrogenesis in the liver of NASH model mice fed a high-cholesterol and high-fat diet. The PPE reduced the number of M1-like liver macrophages, but increased the number of anti-inflammatory M2-like macrophages, resulting in a predominance of M2 over M1 macrophage populations in the liver of NASH mice. Accordingly, the PPE suppressed lipopolysaccharide-induced M1 polarization in isolated murine peritoneal macrophages, whereas it facilitated interleukin 4-induced M2 polarization. Furthermore, the PPE reduced the hepatic stellate cell (HSC) activation associated with the attenuated transforming growth factor-β/Smad3 signaling, both in the liver of NASH mice and in RI-T cells, a HSC line. The PPE may be a potential approach to prevent NASH by limiting lipid peroxidation, promoting M2 macrophage polarization, and attenuating HSC activation.

Type-2 diabetes alters the basal phenotype of human macrophages and diminishes their capacity to respond, internalise, and control Mycobacterium tuberculosis

BACKGROUND

Type 2 diabetes (T2D) is a risk factor for the development of tuberculosis (TB), although the associated mechanisms are not known.

OBJECTIVES

To study the association between T2D and the basal phenotype of macrophages, and their immune response to Mycobacterium tuberculosis (Mtb) infection.

METHODS

We evaluated the influence of T2D on the response of monocyte-derived macrophages (MDM) to Mtb in patients with T2D (n = 10) compared to healthy subjects (n = 9), before and after infection with Mtb clinical isolates bearing different degrees of virulence. The levels of cell surface markers for activation secreted cytokines and chemokines, bacterial association, and intracellular bacterial growth were evaluated.

FINDINGS

The expression levels of HLA-DR, CD80, and CD86 were low while those of of PD-L1 were high in uninfected MDMs derived from patients with diabetes; as a result of Mtb infection, changes were only observed in the expression levels of PD-L1. The levels of cytokines (e.g., IL-6, IL-1β, IL-10, and IL-12) and chemokines (e.g., MCP-1, MIG, and RANTES) are perturbed in MDMs derived from patients with diabetes, both before infection and in response to Mtb infection. In response to the more virulent Mtb strains, the levels of association and bacterial clearance were diminished in MDMs derived from patients with diabetes.

CONCLUSIONS

T2D affects the basal activation state of the macrophages and its capacity to respond and control Mtb infection.

Short-term treatment with metformin reduces hepatic lipid accumulation but induces liver inflammation in obese mice

The study aimed to evaluate the metabolic and inflammatory effects of short-term treatments (10 days) with metformin (MET) on the NAFLD caused by a high-fat diet (HFD) in C57BL/6 mice. After the treatment, histological liver slices were obtained, hepatocytes and macrophages were extracted and cultured with phosphate buffered saline, LPS (2.5 µg/mL) and MET (1 µM) for 24 h. Cytokine levels were determined by ELISA. NAFLD caused by the HFD was partially reduced by MET. The lipid accumulation induced by the HFD was not associated with liver inflammation; however, MET seemed to promote pro-inflammatory effects in liver, since it increased hepatic concentration of IL-1β, TNF-α, IL-6, MCP-1 and IFN-γ. Similarly, MET increased the concentration of IL-1β, IL-6 in hepatocyte cultures. However, in macrophages culture, MET lowered levels of IL-1β, IL-6 and TNF-α stimulated by LPS. Overall, MET reduced liver NAFLD but promoted hepatocyte increase in pro-inflammatory cytokines, thus, leading to liver inflammation.

Unravelling the role of fatty acid metabolism in cancer through the FOXO3-FOXM1 axis

Obesity and cachexia represent divergent states of nutritional and metabolic imbalance but both are intimately linked to cancer. There is an extensive overlap in their signalling pathways and molecular components involved such as fatty acids (FAs), which likely play a crucial role in cancer. Forkhead box (FOX) proteins are responsible of a wide range of transcriptional programmes during normal development, and the FOXO3-FOXM1 axis is associated with cancer initiation, progression and drug resistance. Free fatty acids (FFAs), FA synthesis and β-oxidation are associated with cancer development and progression. Meanwhile, insulin and some adipokines, that are up-regulated by FAs, are also involved in cancer development and poor prognosis. In this review, we discuss the role of FA metabolism in cancer and how FA metabolism integrates with the FOXO3-FOXM1 axis. These new insights may provide leads to better cancer diagnostics as well as strategies for tackling cancer development, progression and drug resistance.

Disruption of the gut-liver axis in the pathogenesis of acute-on-chronic liver failure

Acute-on-chronic liver failure (ACLF) is characterized by organ failure mediated by acute decompensation of cirrhosis. Recent studies have highlighted the importance of the gut-liver axis (GLS) and its association with ACLF pathogenesis. In this review, we discuss the mechanisms related to the alteration of the GLA and their involvement in ACLF pathogenesis and suggest some possible therapeutic options that could modulate the GLA dysfunction. This knowledge may provide information useful for the design of therapeutic strategies for gut dysbiosis and its complications in ACLF.

Emerging roles of SGLT2 inhibitors in obesity and insulin resistance: Focus on fat browning and macrophage polarization

Obesity-associated low-grade inflammation underlies insulin resistance and associated metabolic comorbidities, such as type 2 diabetes (T2D) and nonalcoholic fatty liver disease. Excessive ectopic fat deposition in obesity causes disorders of energy homeostasis and low-grade chronic inflammation in metabolic tissues. In particular, obesity-induced recruitment and activation of adipose tissue macrophages play a key role in the pathogenesis of insulin resistance and T2D. Therefore, treatment options for energy metabolism and macrophage polarization in obese subjects are needed. Sodium-glucose cotransporter (SGLT) 2 inhibitors increase urinary glucose excretion by inhibiting renal glucose reabsorption, thereby having subsequent anti-hyperglycemic effects and reducing body weight. We recently reported that the SGLT2 inhibitor empagliflozin increases fat utilization and browning in white adipose tissue and attenuates obesity-induced inflammation and insulin resistance by activating M2 macrophages. Thus, this review focuses on the beneficial effects of empagliflozin in energy homeostasis and obesity-related inflammation and insulin resistance.

Galectin-3: One Molecule for an Alphabet of Diseases, from A to Z

Galectin-3 (Gal-3) regulates basic cellular functions such as cell-cell and cell-matrix interactions, growth, proliferation, differentiation, and inflammation. It is not surprising, therefore, that this protein is involved in the pathogenesis of many relevant human diseases, including cancer, fibrosis, chronic inflammation and scarring affecting many different tissues. The papers published in the literature have progressively increased in number during the last decades, testifying the great interest given to this protein by numerous researchers involved in many different clinical contexts. Considering the crucial role exerted by Gal-3 in many different clinical conditions, Gal-3 is emerging as a new diagnostic, prognostic biomarker and as a new promising therapeutic target. The current review aims to extensively examine the studies published so far on the role of Gal-3 in all the clinical conditions and diseases, listed in alphabetical order, where it was analyzed.