Interleukin-6 signaling in liver-parenchymal cells suppresses hepatic inflammation and improves systemic insulin action

Glycyrrhizic acid alleviates concanavalin A-induced acute liver injury by regulating monocyte-derived macrophages

Autoimmune hepatitis (AIH) is characterized by persistent liver inflammation induced by aberrant immune responses. Glycyrrhizic acid (GA), a prominent bioactive ingredient of licorice, has shown potential as a safe and effective treatment for AIH. However, the immune regulatory mechanism by which GA exerts its therapeutic effect on AIH remains elusive. In this study, we found that GA intervention significantly alleviated ConA-induced acute liver injury in mice. Cytometry by time-of-flight (CyTOF) analysis revealed that GA increased the abundance of anti-inflammatory F4/80loCD11bhiMHCIIhi MoMF-1 and decreased the abundance of pro-inflammatory F4/80loCD11bhiiNOShi MoMF-3. Multiplex immunofluorescence demonstrated the infiltration of MoMFs in liver tissues. Single-cell RNA sequencing (scRNA-seq) analysis indicated that GA facilitated the immune activation in MoMFs, regulated gene expression of diverse cytokines secreted by MoMFs, and played a role in shaping the immune microenvironment. By integrating the results of CyTOF with scRNA-seq, our study comprehensively elucidates the immune landscape of ConA-induced liver injury following GA intervention, advancing the understanding of GA's mechanism of action. However, it is important to note that some single-cell data in this study remain raw and require further processing and annotation. Our findings suggest that GA alleviates ConA-induced acute liver injury by regulating the function of MoMFs, opening potential avenues for AIH treatment and management, and providing a theoretical basis for the design of novel MoMFs-centered immunotherapies.

Dysfunction of the Murine Liver with Aging and Its Improvement with the Continuous Consumption of Enterococcus faecalis EC-12

Chronic inflammation is involved in the development of age-related diseases. Given its persistence, controlling chronic inflammation is essential for preventing age-related diseases. In this study, we investigated the effects of Enterococcus faecalis EC-12 (EC-12), which has immunomodulatory and antioxidant effects, on liver gene expression and aging phenomena in mice. Short-term EC-12 administration stimulated the expression of genes involved in lipid synthesis and metabolism in the liver. Furthermore, long-term EC-12 administration from 10 weeks to 1.5 years of age resulted in significant increases in blood interleukin (IL)-6 and IL-10 concentrations (both p < 0.05) and a significant decrease in the monocyte chemotactic protein-1 concentration (p < 0.05). These results indicated pathologic improvement, such as suppression of fat degeneration in the liver. These results suggest that continuous EC-12 intake from a young age can suppress liver function abnormalities, which is one of the aging phenomena in old age, and contribute to health in old age.

Interleukin-6 classic and trans-signaling utilize glucose metabolism reprogramming to achieve anti- or pro-inflammatory effects

Interleukin (IL)-6 has anti- and pro-inflammatory functions, controlled by IL-6 classic and trans-signaling, respectively. Differences in the downstream signaling mechanism between IL-6 classic and trans-signaling have not been identified. Here, we report that IL-6 activates glycolysis to regulate the inflammatory response. IL-6 regulates glucose metabolism by forming a complex containing signal-transducing activators of transcription 3 (STAT3), hexokinase 2 (HK2), and voltage-dependent anion channel 1 (VDAC1). The IL-6 classic signaling directs glucose flux to oxidative phosphorylation (OxPhos), while IL-6 trans-signaling directs glucose flux to anaerobic glycolysis. Classic IL-6 signaling promotes STAT3 translocation into mitochondria to interact with pyruvate dehydrogenase kinase-1 (PDK1), leading to pyruvate dehydrogenase α (PDHA) dissociation from PDK1. As a result, PDHA is dephosphorylated, and STAT3 is phosphorylated at Ser727. By contrast, IL-6 trans-signaling promotes the interaction of sirtuin 2 (SIRT2) and lactate dehydrogenase A (LDHA), leading to the dissociation of STAT3 from SIRT2. As a result, LDHA is deacetylated, and STAT3 is acetylated and phosphorylated at Tyr705. IL-6 classic signaling promotes the differentiation of regulatory T cells via the PDK1/STAT3/PDHA axis, whereas IL-6 trans-signaling promotes the differentiation of Th17 cells via the SIRT2/STAT3/LDHA axis. Conclusion: IL-6 classic signaling generates anti-inflammatory functions by shifting energy metabolism to OxPhos, while IL-6 trans-signaling generates pro-inflammatory functions by shifting energy metabolism to anaerobic glycolysis.

Clinically relevant plasma proteome for adiposity depots: evidence from systematic mendelian randomization and colocalization analyses

BACKGROUND

The accumulation of visceral and ectopic fat comprise a major cause of cardiometabolic diseases. However, novel drug targets for reducing unnecessary visceral and ectopic fat are still limited. Our study aims to provide a comprehensive investigation of the causal effects of the plasma proteome on visceral and ectopic fat using Mendelian randomization (MR) approach.

METHODS

We performed two-sample MR analyses based on five large genome-wide association study (GWAS) summary statistics of 2656 plasma proteins, to screen for causal associations of these proteins with traits of visceral and ectopic fat in over 30,000 participants of European ancestry, as well as to assess mediation effects by risk factors of outcomes. The colocalization analysis was conducted to examine whether the identified proteins and outcomes shared casual variants.

RESULTS

Genetically predicted levels of 14 circulating proteins were associated with visceral and ectopic fat (P < 4.99 × 10- 5, at a Bonferroni-corrected threshold). Colocalization analysis prioritized ten protein targets that showed effect on outcomes, including FST, SIRT2, DNAJB9, IL6R, CTSA, RGMB, PNLIPRP1, FLT4, PPY and IL6ST. MR analyses revealed seven risk factors for visceral and ectopic fat (P < 0.0024). Furthermore, the associations of CTSA, DNAJB9 and IGFBP1 with primary outcomes were mediated by HDL-C and SHBG. Sensitivity analyses showed little evidence of pleiotropy.

CONCLUSIONS

Our study identified candidate proteins showing putative causal effects as potential therapeutic targets for visceral and ectopic fat accumulation and outlined causal pathways for further prevention of downstream cardiometabolic diseases.

Exerkines and cardiometabolic benefits of exercise: from bench to clinic

Regular exercise has both immediate and long-lasting benefits on cardiometabolic health, and has been recommended as a cornerstone of treatment in the management of diabetes and cardiovascular conditions. Exerkines, which are defined as humoral factors responsive to acute or chronic exercise, have emerged as important players conferring some of the multiple cardiometabolic benefits of exercise. Over the past decades, hundreds of exerkines released from skeletal muscle, heart, liver, adipose tissue, brain, and gut have been identified, and several exerkines (such as FGF21, IL-6, and adiponectin) have been exploited therapeutically as exercise mimetics for the treatment of various metabolic and cardiovascular diseases. Recent advances in metagenomics have led to the identification of gut microbiota, a so-called "hidden" metabolic organ, as an additional class of exerkines determining the efficacy of exercise in diabetes prevention, cardiac protection, and exercise performance. Furthermore, multiomics-based studies have shown the feasibility of using baseline exerkine signatures to predict individual responses to exercise with respect to metabolic and cardiorespiratory health. This review aims to explore the molecular pathways whereby exerkine networks mediate the cardiometabolic adaptations to exercise by fine-tuning inter-organ crosstalk, and discuss the roadmaps for translating exerkine-based discovery into the therapeutic application and personalized medicine in the management of the cardiometabolic disease.

Research Advances in Fusion Protein-Based Drugs for Diabetes Treatment

Diabetes mellitus (DM) is a chronic metabolic disease characterized by elevated blood glucose levels, resulting in multi-organ dysfunction and various complications. Fusion proteins can form multifunctional complexes by combining the target proteins with partner proteins. It has significant advantages in improving the performance of the target proteins, extending their biological half-life, and enhancing patient drug compliance. Fusion protein-based drugs have emerged as promising new drugs in diabetes therapeutics. However, there has not been a systematic review of fusion protein-based drugs for diabetes therapeutics. Hence, we conducted a comprehensive review of published literature on diabetic fusion protein-based drugs for diabetes, with a primary focus on immunoglobulin G (IgG) fragment crystallizable (Fc) region, albumin, and transferrin (TF). This review aims to provide a reference for the subsequent development and clinical application of fusion protein-based drugs in diabetes therapeutics.

Adiponectin: A Promising Target for the Treatment of Diabetes and Its Complications

Diabetes mellitus, a chronic metabolic disorder characterized by hyperglycemia, presents a formidable global health challenge with its associated complications. Adiponectin, an adipocyte-derived hormone, has emerged as a significant player in glucose metabolism and insulin sensitivity. Beyond its metabolic effects, adiponectin exerts anti-inflammatory, anti-oxidative, and vasoprotective properties, making it an appealing therapeutic target for mitigating diabetic complications. The molecular mechanisms by which adiponectin impacts critical pathways implicated in diabetic nephropathy, retinopathy, neuropathy, and cardiovascular problems are thoroughly examined in this study. In addition, we explore possible treatment options for increasing adiponectin levels or improving its downstream signaling. The multifaceted protective roles of adiponectin in diabetic complications suggest its potential as a novel therapeutic avenue. However, further translational studies and clinical trials are warranted to fully harness the therapeutic potential of adiponectin in the management of diabetic complications. This review highlights adiponectin as a promising target for the treatment of diverse diabetic complications and encourages continued research in this pivotal area of diabetes therapeutics.

Interleukin-6 signaling in osteoblasts regulates bone remodeling during exercise

Aerobic exercise has many beneficial effects on human health. One of them, is to influence positively bone remodeling through, however, incompletely understood mechanisms. Given its recently demonstrated role as a mediator of the bone to muscle to bone crosstalk during exercise, we hypothesized that interleukin-6 (IL-6) signaling in bone may contribute to the beneficial effect that exercise has on bone homeostasis. In this study, we first show that aerobic exercise increases the expression of Il6r in bones of WT mice. Then, we analyzed a mutant mouse strain that lacks the IL-6 receptor alpha specifically in osteoblasts (Il6rosb-/-). As it has been reported in the case of Il6-/- mice, in sedentary conditions, bone mass and remodeling were normal in adult Il6rosb-/- mice when compared to controls. In contrast, Il6rosb-/- mice that were subjected to aerobic exercise did not show the increase in bone mass and remodeling parameters that control littermates demonstrated. Moreover, Il6rosb-/- mice undergoing aerobic exercise showed a severe impairment in bone formation, indicating that activation of bone-forming cells is defective when IL-6 signaling in osteoblasts is disrupted. In sum, this study provides evidence that a function of IL-6 signaling in osteoblasts is to promote high bone turnover during aerobic exercise.

The exercise IL-6 enigma in cancer

Interleukin (IL)-6 elicits both anticancer and procancer effects depending on the context, which we have termed the 'exercise IL-6 enigma'. IL-6 is released from skeletal muscles during exercise to regulate short-term energy availability. Exercise-induced IL-6 provokes biological effects that may protect against cancer by improving insulin sensitivity, stimulating the production of anti-inflammatory cytokines, mobilising immune cells, and reducing DNA damage in early malignant cells. By contrast, IL-6 continuously produced by leukocytes in inflammatory sites drives tumorigenesis by promoting chronic inflammation and activating tumour-promoting signalling pathways. How can a molecule have such opposing effects on cancer? Here, we review the roles of IL-6 in chronic inflammation, tumorigenesis, and exercise-associated cancer prevention and define the factors that underpin the exercise IL-6 enigma.

Regulatory T cells require IL6 receptor alpha signaling to control skeletal muscle function and regeneration

Muscle-residing regulatory T cells (Tregs) control local tissue integrity and function. However, the molecular interface connecting Treg-based regulation with muscle function and regeneration remains largely unexplored. Here, we show that exercise fosters a stable induction of highly functional muscle-residing Tregs with increased expression of amphiregulin (Areg), EGFR, and ST2. Mechanistically, we find that mice lacking IL6Rα on T cells (TKO) harbor significant reductions in muscle Treg functionality and satellite and fibro-adipogenic progenitor cells, which are required for muscle regeneration. Using exercise and sarcopenia models, IL6Rα TKO mice demonstrate deficits in Tregs, their functional maturation, and a more pronounced decline in muscle mass. Muscle injury models indicate that IL6Rα TKO mice have significant disabilities in muscle regeneration. Treg gain of function restores impaired muscle repair in IL6Rα TKO mice. Of note, pharmacological IL6R blockade in WT mice phenocopies deficits in muscle function identified in IL6Rα TKO mice, thereby highlighting the clinical implications of the findings.

Differential Roles of Interleukin-6 in Severe Acute Respiratory Syndrome-Coronavirus-2 Infection and Cardiometabolic Diseases

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection can lead to a cytokine storm, unleashed in part by pyroptosis of virus-infected macrophages and monocytes. Interleukin-6 (IL-6) has emerged as a key participant in this ominous complication of COVID-19. IL-6 antagonists have improved outcomes in patients with COVID-19 in some, but not all, studies. IL-6 signaling involves at least 3 distinct pathways, including classic-signaling, trans-signaling, and trans-presentation depending on the localization of IL-6 receptor and its binding partner glycoprotein gp130. IL-6 has become a therapeutic target in COVID-19, cardiovascular diseases, and other inflammatory conditions. However, the efficacy of inhibition of IL-6 signaling in metabolic diseases, such as obesity and diabetes, may depend in part on cell type-dependent actions of IL-6 in controlling lipid metabolism, glucose uptake, and insulin sensitivity owing to complexities that remain to be elucidated. The present review sought to summarize and discuss the current understanding of how and whether targeting IL-6 signaling ameliorates outcomes following SARS-CoV-2 infection and associated clinical complications, focusing predominantly on metabolic and cardiovascular diseases.

Adipokines in obesity and metabolic-related-diseases

The discovery of leptin in the 1990s led to a reconsideration of adipose tissue (AT) as not only a fatty acid storage organ, but also a proper endocrine tissue. AT is indeed capable of secreting bioactive molecules called adipokines for white AT or batokines for brown/beige AT, which allow communication with numerous organs, especially brain, heart, liver, pancreas, and/or the vascular system. Adipokines exert pro or anti-inflammatory activities. An equilibrated balance between these two sets ensures homeostasis of numerous tissues and organs. During the development of obesity, AT remodelling leads to an alteration of its endocrine activity, with increased secretion of pro-inflammatory adipokines relative to the anti-inflammatory ones, as shown in the graphical abstract. Pro-inflammatory adipokines take part in the initiation of local and systemic inflammation during obesity and contribute to comorbidities associated to obesity, as detailed in the present review.

Physiological role of cytokines in the regulation of mammalian metabolism

The innate cytokine system is involved in the response to excessive food intake. In this review, we highlight recent advances in our understanding of the physiological role of three prominent cytokines, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF), in mammalian metabolic regulation. This recent research highlights the pleiotropic and context-dependent functions in the immune-metabolic interplay. IL-1β is activated in response to overloaded mitochondrial metabolism, stimulates insulin secretion, and allocates energy to immune cells. IL-6 is released by contracting skeletal muscle and adipose tissue and directs energy from storing tissues to consuming tissues. TNF induces insulin resistance and prevents ketogenesis. Additionally, the therapeutic potential of modulating the activity of each cytokine is discussed.

Signaling pathways and intervention for therapy of type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) represents one of the fastest growing epidemic metabolic disorders worldwide and is a strong contributor for a broad range of comorbidities, including vascular, visual, neurological, kidney, and liver diseases. Moreover, recent data suggest a mutual interplay between T2DM and Corona Virus Disease 2019 (COVID-19). T2DM is characterized by insulin resistance (IR) and pancreatic β cell dysfunction. Pioneering discoveries throughout the past few decades have established notable links between signaling pathways and T2DM pathogenesis and therapy. Importantly, a number of signaling pathways substantially control the advancement of core pathological changes in T2DM, including IR and β cell dysfunction, as well as additional pathogenic disturbances. Accordingly, an improved understanding of these signaling pathways sheds light on tractable targets and strategies for developing and repurposing critical therapies to treat T2DM and its complications. In this review, we provide a brief overview of the history of T2DM and signaling pathways, and offer a systematic update on the role and mechanism of key signaling pathways underlying the onset, development, and progression of T2DM. In this content, we also summarize current therapeutic drugs/agents associated with signaling pathways for the treatment of T2DM and its complications, and discuss some implications and directions to the future of this field.

Colorable role of interleukin (IL)-6 in obesity hypertension: A hint from a Chinese adult case-control study

BACKGROUND

Obesity and hypertension are major risk factors for cardiovascular diseases that affect millions of people worldwide. Both conditions are associated with chronic low-grade inflammation, which is mediated by cytokines such as interleukin-6 (IL-6). IL-6 is a multifunctional cytokine that can have pro-inflammatory or anti-inflammatory effects depending on the context. The exact role of IL-6 in obesity-associated hypertension is unclear.

OBJECTIVE

To investigate how IL-6 affects blood pressure, inflammation, and metabolic function in obesity-hypertension using a Chinese adult case-control study.

METHODS

A total of 153 participants were sorted into four subgroups according to their body mass index (BMI) and blood pressure (BP): normal healthy group (NH), just obesity group (JO), just-hypertension group (JH), and obesity-hypertension group (OH). Serum IL-6 concentrations were measured by Enzyme-linked Immunosorbent Assay (ELISA) and their correlations with anthropometric and laboratory parameters and their differences across the subgroups were examined. Multiple linear regression analysis was performed to identify the predictors of serum IL-6 concentrations in each group.

RESULTS

Serum IL-6 concentrations were higher in NH group than in JO group and correlated positively with diastolic blood pressure in NH and JO groups, but not in JH and OH groups. Serum IL-6 concentrations also correlated with albumin in NH group, alkaline phosphatase in JO group, serum creatinine and fasting blood glucose in JH group. The influencing factors of serum IL-6 concentrations varied among the four groups, with gender, diastolic blood pressure and albumin being significant predictors in NH group, alkaline phosphatase in JO group, age and serum creatinine in JH group, and none in OH group.

CONCLUSIONS

These results suggest that IL-6 may play diverse effects in the pathogenesis of obesity- hypertension, depending on the presence or absence of obesity and hypertension. Further studies are needed to elucidate the underlying mechanisms of IL-6 signaling and function in these diseases.

Clonal haematopoiesis and risk of chronic liver disease

Chronic liver disease is a major public health burden worldwide1. Although different aetiologies and mechanisms of liver injury exist, progression of chronic liver disease follows a common pathway of liver inflammation, injury and fibrosis2. Here we examined the association between clonal haematopoiesis of indeterminate potential (CHIP) and chronic liver disease in 214,563 individuals from 4 independent cohorts with whole-exome sequencing data (Framingham Heart Study, Atherosclerosis Risk in Communities Study, UK Biobank and Mass General Brigham Biobank). CHIP was associated with an increased risk of prevalent and incident chronic liver disease (odds ratio = 2.01, 95% confidence interval (95% CI) [1.46, 2.79]; P < 0.001). Individuals with CHIP were more likely to demonstrate liver inflammation and fibrosis detectable by magnetic resonance imaging compared to those without CHIP (odds ratio = 1.74, 95% CI [1.16, 2.60]; P = 0.007). To assess potential causality, Mendelian randomization analyses showed that genetic predisposition to CHIP was associated with a greater risk of chronic liver disease (odds ratio = 2.37, 95% CI [1.57, 3.6]; P < 0.001). In a dietary model of non-alcoholic steatohepatitis, mice transplanted with Tet2-deficient haematopoietic cells demonstrated more severe liver inflammation and fibrosis. These effects were mediated by the NLRP3 inflammasome and increased levels of expression of downstream inflammatory cytokines in Tet2-deficient macrophages. In summary, clonal haematopoiesis is associated with an elevated risk of liver inflammation and chronic liver disease progression through an aberrant inflammatory response.

Diet-induced gut dysbiosis and inflammation: Key drivers of obesity-driven NASH

Sucrose, the primary circulating sugar in plants, contains equal amounts of fructose and glucose. The latter is the predominant circulating sugar in animals and thus the primary fuel source for various tissue and cell types in the body. Chronic excessive energy intake has, however, emerged as a major driver of obesity and associated pathologies including nonalcoholic fatty liver diseases (NAFLD) and the more severe nonalcoholic steatohepatitis (NASH). Consumption of a high-caloric, western-style diet induces gut dysbiosis and inflammation resulting in leaky gut. Translocation of gut-derived bacterial content promotes hepatic inflammation and ER stress, and when either or both of these are combined with steatosis, it can cause NASH. Here, we review the metabolic links between diet-induced changes in the gut and NASH. Furthermore, therapeutic interventions for the treatment of obesity and liver metabolic diseases are also discussed with a focus on restoring the gut-liver axis.

Deficiency of interleukin-6 receptor ameliorates PM2.5 exposure-induced pulmonary dysfunction and inflammation but not abnormalities in glucose homeostasis

BACKGROUND

Ambient fine particulate matter (PM_2.5) exposure increases local and systemic interleukin-6 (IL-6). However, the pathogenic role of IL-6 signalling following PM_2.5 exposure, particularly in the development of pulmonary dysfunction and abnormal glucose homeostasis, has hardly been investigated.

RESULTS

In the study, IL-6 receptor (IL-6R)-deficient (IL-6R^-/-) and wildtype littermate (IL-6R^+/+) mice were exposed to concentrated ambient PM_2.5 (CAP) or filtered air (FA), and their pulmonary and metabolic responses to these exposures were analyzed. Our results demonstrated that IL-6R deficiency markedly alleviated PM_2.5 exposure-induced increases in lung inflammatory markers including the inflammation score of histological analysis, the number of macrophages in bronchoalveolar lavage fluid (BALF), and mRNA expressions of TNFα, IL-1β and IL-6 and abnormalities in lung function test. However, IL-6R deficiency did not reduce the hepatic insulin resistance nor systemic glucose intolerance and insulin resistance induced by PM_2.5 exposure.

CONCLUSION

Our findings support the crucial role of IL-6 signalling in the development of pulmonary inflammation and dysfunction due to PM_2.5 exposure but question the putative central role of pulmonary inflammation for the extra-pulmonary dysfunctions following PM_2.5 exposure, providing a deep mechanistic insight into the pathogenesis caused by PM_2.5 exposure.

Macrophages, Chronic Inflammation, and Insulin Resistance

The prevalence of obesity has reached alarming levels, which is considered a major risk factor for several metabolic diseases, including type 2 diabetes (T2D), non-alcoholic fatty liver, atherosclerosis, and ischemic cardiovascular disease. Obesity-induced chronic, low-grade inflammation may lead to insulin resistance, and it is well-recognized that macrophages play a major role in such inflammation. In the current review, the molecular mechanisms underlying macrophages, low-grade tissue inflammation, insulin resistance, and T2D are described. Also, the role of macrophages in obesity-induced insulin resistance is presented, and therapeutic drugs and recent advances targeting macrophages for the treatment of T2D are introduced.

Contribution of organokines in the development of NAFLD/NASH associated hepatocellular carcinoma

Globally the incidence of hepatocellular carcinoma (HCC) is on an upsurge. Evidence is accumulating that liver disorders like nonalcoholic fatty liver disease (NAFLD) and its more progressive form nonalcoholic steatohepatitis (NASH) are associated with increased risk of developing HCC. NAFLD has a prevalence of about 25% and 50%-90% in obese population. With the growing burden of obesity epidemic worldwide, HCC presents a major healthcare burden. While cirrhosis is one of the major risk factors of HCC, available literature suggests that NAFLD/NASH associated HCC also develops in minimum or noncirrhotic livers. Therefore, there is an urgent need to understand the pathogenesis and risk factors associated with NAFLD and NASH related HCC that would help in early diagnosis and favorable prognosis of HCC secondary to NAFLD. Adipokines, hepatokines and myokines are factors secreted by adipocytes, hepatocytes and myocytes, respectively, playing essential roles in cellular homeostasis, energy balance and metabolism with autocrine, paracrine and endocrine effects. In this review, we endeavor to focus on the role of these organokines in the pathogenesis of NAFLD/NASH and its progression to HCC to augment the understanding of the factors stimulating hepatocytes to acquire a malignant phenotype. This shall aid in the development of novel therapeutic strategies and tools for early diagnosis of NAFLD/NASH and HCC.

Revisiting the role of Akkermansia muciniphila as a therapeutic bacterium

Despite a short history since its first isolation, Akkermansia muciniphila has been extensively studied in relation to its effects on human metabolism. A recent human intervention study also demonstrated that the bacterium is safe to use for therapeutic purposes. The best-known effects of A. muciniphila in human health and disease relate to its ability to strengthen gut integrity, modulate insulin resistance, and protect the host from metabolic inflammation. A further molecular mechanism, induction of GLP-1 secretion through ICAM-2 receptor, was recently discovered with the identification of a new bacterial protein produced by A. muciniphila. However, other studies have suggested a detrimental role for A. muciniphila in specific host immune settings. Here, we evaluate the molecular, mechanistic effects of A. muciniphila in host health and suggest some of the missing links to be connected before the organism should be considered as a next-generation biotherapeutic agent.

Administration of Hookworm Excretory/Secretory Proteins Improves Glucose Tolerance in a Mouse Model of Type 2 Diabetes

Diabetes is recognised as the world’s fastest growing chronic condition globally. Helminth infections have been shown to be associated with a lower prevalence of type 2 diabetes (T2D), in part due to their ability to induce a type 2 immune response. Therefore, to understand the molecular mechanisms that underlie the development of T2D-induced insulin resistance, we treated mice fed on normal or diabetes-promoting diets with excretory/secretory products (ES) from the gastrointestinal helminth Nippostrongylus brasiliensis. We demonstrated that treatment with crude ES products from adult worms (AES) or infective third-stage larvae (L3ES) from N. brasiliensis improved glucose tolerance and attenuated body weight gain in mice fed on a high glycaemic index diet. N. brasiliensis ES administration to mice was associated with a type 2 immune response measured by increased eosinophils and IL-5 in peripheral tissues but not IL-4, and with a decrease in the level of IL-6 in adipose tissue and corresponding increase in IL-6 levels in the liver. Moreover, treatment with AES or L3ES was associated with significant changes in the community composition of the gut microbiota at the phylum and order levels. These data highlight a role for N. brasiliensis ES in modulating the immune response associated with T2D, and suggest that N. brasiliensis ES contain molecules with therapeutic potential for treating metabolic syndrome and T2D.

FTO knockout in adipose tissue effectively alleviates hepatic steatosis partially via increasing the secretion of adipocyte-derived IL-6

OBJECTIVE

Adipose dysfunction affects the secretion of adipokines and mediates the hepatic physiological changes. Fat mass and obesity associated protein (FTO) plays a crucial part in fat deposition but the crosstalk between FTO-mediated secretion of adipokines and hepatic steatosis is not clear.

METHODS

Firstly, adipose-selective FTO knockout (FTOAKO) and control (FTOflox/flox) mice were induced by high fat diet (HFD). Then qRT-PCR assay was performed to analyze the expressions of hepatic lipid metabolism genes and adipocytokines gene of inguinal white adipose tissue (iWAT) and epididymal white adipose tissue (eWAT). Afterwards, 3T3-L1 cells were knocked out IL-6 and co-cultured with AML12 cells (3T3-L1 siIL-6/AML12) and the expressions of hepatic lipid lipolysis genes were measured. Finally, we detected the hepatic lipid metabolism genes expressions in AML12 cells with the medium from 3T3-L1 cells or IL-6 treatment.

RESULTS

FTOAKO effectively alleviated HFD-induced hepatic steatosis in mice and improved the transcription level of genes involved in hepatic lipolysis. Further investigation demonstrated that FTO knockout increased level of IL-6 in adipose tissues and 3T3-L1 cells. Compared to 3T3-L1/AML12, our results showed lipolysis-related genes expressions were dramatically inhibited in 3T3-L1 siIL-6/AML12. Finally, both depletion of FTO in adipocytes and IL-6 supplement led to increased lipolysis genes expressions in AML12 cells.

CONCLUSIONS

FTO knockout in adipose tissue alleviated hepatic steatosis via targeting adipocyte-derived IL-6.

Hepatic IRF3 fuels dysglycemia in obesity through direct regulation of Ppp2r1b

Inflammation has profound but poorly understood effects on metabolism, especially in the context of obesity and nonalcoholic fatty liver disease (NAFLD). Here, we report that hepatic interferon regulatory factor 3 (IRF3) is a direct transcriptional regulator of glucose homeostasis through induction of Ppp2r1b, a component of serine/threonine phosphatase PP2A, and subsequent suppression of glucose production. Global ablation of IRF3 in mice on a high-fat diet protected against both steatosis and dysglycemia, whereas hepatocyte-specific loss of IRF3 affects only dysglycemia. Integration of the IRF3-dependent transcriptome and cistrome in mouse hepatocytes identifies Ppp2r1b as a direct IRF3 target responsible for mediating its metabolic actions on glucose homeostasis. IRF3-mediated induction of Ppp2r1b amplified PP2A activity, with subsequent dephosphorylation of AMPKα and AKT. Furthermore, suppression of hepatic Irf3 expression with antisense oligonucleotides reversed obesity-induced insulin resistance and restored glucose homeostasis in obese mice. Obese humans with NAFLD displayed enhanced activation of liver IRF3, with reversion after bariatric surgery. Hepatic PPP2R1B expression correlated with HgbA1C and was elevated in obese humans with impaired fasting glucose. We therefore identify the hepatic IRF3-PPP2R1B axis as a causal link between obesity-induced inflammation and dysglycemia and suggest an approach for limiting the metabolic dysfunction accompanying obesity-associated NAFLD.

Interleukins in adipose tissue: Keeping the balance

The role of the immune system is to defend the host and preserve the functionality in response to stress. This function is not limited to infection or injury as it also plays a role in the response to overnutrition. Indeed, low-grade chronic activation of the immune system associated with overnutrition may be deleterious, contributing importantly to diabetes and long-term complications, such as cardiovascular disorders. Increasing evidence shows that adipose tissue participates in the obesity-related inflammatory response and that interleukins are one of the key players, either as a pro-inflammatory response to the metabolic dysregulation or to restore homeostasis. The crosstalk between adipocytes and immune cells through some important interleukins and their role in metabolic disruption is the topic of this review.

Interleukin 6 receptor is not directly involved in regulation of body weight in diet-induced obesity with and without physical exercise

High level of interleukin 6 (IL-6), released by adipocytes in an obesity-induced, low grade inflammation state, is a regulator of insulin resistance and glucose tolerance. IL-6 has also regenerative, anti-inflammatory and anti-diabetogenic functions, when secreted as myokine by skeletal muscles during physical exercise. IL-6 mainly activates cells via two different receptor constellations: classic and trans-signalling, in which IL-6 initially binds to membrane-bound receptor (IL-6R) or soluble IL-6 receptor (sIL-6R) before activating signal transducing gp130 receptor. Previously, we generated transgenic soluble IL-6 receptor ^+/+ (sIL-6R^+/+) mice with a strategy that mimics ADAM10/17 hyperactivation, reflecting a situation in which only IL-6 trans-signalling is active, whereas classic signalling is completely abrogated. In this study, we metabolically phenotyped IL-6R deficient mice (IL-6R-KO), sIL-6R^+/+ mice and wild-type littermates fed either a standard chow (SD) or a high-fat diet (HFD) in combination with a 6-weeks treadmill exercise protocol. All mice were subjected to analyses of body weight and body composition, determination of blood glucose and insulin level under fasting conditions, as well as determination of substrate preference by indirect calorimetry. Neither classic IL-6 nor trans-signalling do influence the outcome of diet-induced obesity, insulin sensitivity and glycaemic control. Furthermore, IL-6R deficiency is not impairing the beneficial effect of physical exercise. We conclude that the IL-6R does not play a requisite role in regulation of body weight and glucose metabolism in diet-induced obese mice.

Novel drug discovery strategies for the treatment of decompensated cirrhosis

INTRODUCTION

Disease progression in cirrhosis leads to decompensation and acute-on-chronic liver failure (ACLF), which is characterized by organ failure and high mortality. Portal hypertension and cardiovascular dysfunction trigger the development of cirrhosis-related complications whilst tissue injury and cellular metabolic dysfunction lead to organ failure. System inflammation is the overarching mechanism mediating both the transition from compensation to decompensation as well as progression to ACLF. Treatment of precipitating events and intensive organ support is the only established therapeutic strategies. Liver transplantationrepresents the only curative therapy but contraindications and organ scarcity limit its availability to only a minority of patients with end-stage liver disease. Therefore, the discovery and development of novel interventions modifying the disease course and improving patients' outcome are of utmost importance.

AREAS COVERED

This review highlights and discusses therapeutic novelties in the field of end-stage liver disease.

EXPERT OPINION

Despite decades of research, there are still no established therapies to improve the devastating prognosis of patients with end-stage liver disease. The clinical heterogeneity and complex pathogenesis will put high demands on drug discovery. Combinatorial therapies tailored to the patients' individual pattern of pathomechanisms may be the most efficient way to modify disease course.

Innate-Immunity Genes in Obesity

The main functions of adipose tissue are thought to be storage and mobilization of the body’s energy reserves, active and passive thermoregulation, participation in the spatial organization of internal organs, protection of the body from lipotoxicity, and ectopic lipid deposition. After the discovery of adipokines, the endocrine function was added to the above list, and after the identification of crosstalk between adipocytes and immune cells, an immune function was suggested. Nonetheless, it turned out that the mechanisms underlying mutual regulatory relations of adipocytes, preadipocytes, immune cells, and their microenvironment are complex and redundant at many levels. One possible way to elucidate the picture of adipose-tissue regulation is to determine genetic variants correlating with obesity. In this review, we examine various aspects of adipose-tissue involvement in innate immune responses as well as variants of immune-response genes associated with obesity.

Sympathetic nerve-adipocyte interactions in response to acute stress

Psychological stress predisposes our body to several disorders. Understanding the cellular and molecular mechanisms involved in the physiological responses to psychological stress is essential for the success of therapeutic applications. New studies show, by using in vivo inducible Cre/loxP-mediated approaches in combination with pharmacological blockage, that sympathetic nerves, activated by psychological stress, induce brown adipocytes to produce IL-6. Strikingly, this cytokine promotes gluconeogenesis in hepatocytes, that results in the decline of tolerance to inflammatory organ damage. The comprehension arising from this research will be crucial for the handling of many inflammatory diseases. Here, we review recent advances in our comprehension of the sympathetic nerve-adipocyte axis in the tissue microenvironment.

New insights into IL-6 family cytokines in metabolism, hepatology and gastroenterology

IL-6 family cytokines are defined by the common use of the signal-transducing receptor chain glycoprotein 130 (gp130). Increasing evidence indicates that these cytokines are essential in the regulation of metabolic homeostasis as well as in the pathophysiology of multiple gastrointestinal and liver disorders, thus making them attractive therapeutic targets. Over the past few years, therapies modulating gp130 signalling have grown exponentially in several clinical settings including obesity, cancer and inflammatory bowel disease. A newly engineered gp130 cytokine, IC7Fc, has shown promising preclinical results for the treatment of type 2 diabetes, obesity and liver steatosis. Moreover, drugs that modulate gp130 signalling have shown promise in refractory inflammatory bowel disease in clinical trials. A deeper understanding of the main roles of the IL-6 family of cytokines during homeostatic and pathological conditions, their signalling pathways, sources of production and target cells will be crucial to the development of improved treatments. Here, we review the current state of the role of these cytokines in hepatology and gastroenterology and discuss the progress achieved in translating therapeutics targeting gp130 signalling into clinical practice.

Hepatoprotective effects of sericin on aging-induced liver damage in mice

Aging is a physiological process in which there is a progressive decline of function in multiple organs such as the liver. The development of natural therapies, such as sericin, for delaying age-associated diseases is of major interest in this regard. Twenty-seven mice were divided into three groups of nine, including young control group (8 weeks, received normal saline), aged control group (24 months, received normal saline), and sericin-treated aged mice (24 months, received sericin at dose 100 mg/kg/day) via oral administration for 14 days. The liver enzymes in serum and oxidative stress markers in liver tissue were evaluated using spectrophotometric/ELISA methods. Apoptotic proteins, pro-inflammatory cytokines, COX2, JNK, and P-38 levels were assessed by western blot analysis. β-galactosidase expression was determined by a qRT-PCR method. The findings showed that 100 mg/kg of sericin reduced liver enzymes in aged mice. Antioxidant capacity in treated aged mice showed an improvement in all indexes in the liver tissue. Also, sericin administration declined pro-inflammatory markers to varying degrees in aged-treated mice. Sericin also increased the expression level of Bcl-2 and decreased the expression level of Bax and cleaved caspase-3.In addition, treatment with sericin suppressed protein expression of p-JNK and p-JNK/JNK. Collectively, these findings would infer that sericin administration may have a hepatoprotective effect in aging-induced liver damage in mice.

Akkermansia muciniphila secretes a glucagon-like peptide-1-inducing protein that improves glucose homeostasis and ameliorates metabolic disease in mice

The gut microbiota, which includes Akkermansia muciniphila, is known to modulate energy metabolism, glucose tolerance, immune system maturation and function in humans^1-4. Although A. muciniphila is correlated with metabolic diseases and its beneficial causal effects were reported on host metabolism^5-8, the molecular mechanisms involved have not been identified. Here, we report that A. muciniphila increases thermogenesis and glucagon-like peptide-1 (GLP-1) secretion in high-fat-diet (HFD)-induced C57BL/6J mice by induction of uncoupling protein 1 in brown adipose tissue and systemic GLP-1 secretion. We apply fast protein liquid chromatography and liquid chromatography coupled to mass spectrophotometry analysis to identify an 84 kDa protein, named P9, that is secreted by A. muciniphila. Using L cells and mice fed on an HFD, we show that purified P9 alone is sufficient to induce GLP-1 secretion and brown adipose tissue thermogenesis. Using ligand-receptor capture analysis, we find that P9 interacts with intercellular adhesion molecule 2 (ICAM-2). Interleukin-6 deficiency abrogates the effects of P9 in glucose homeostasis and downregulates ICAM-2 expression. Our results show that the interactions between P9 and ICAM-2 could be targeted by therapeutics for metabolic diseases.

Tissue Homeostasis and Inflammation

There is a growing interest in understanding tissue organization, homeostasis, and inflammation. However, despite an abundance of data, the organizing principles of tissue biology remain poorly defined. Here, we present a perspective on tissue organization based on the relationships between cell types and the functions that they perform. We provide a formal definition of tissue homeostasis as a collection of circuits that regulate specific variables within the tissue environment, and we describe how the functional organization of tissues allows for the maintenance of both tissue and systemic homeostasis. This leads to a natural definition of inflammation as a response to deviations from homeostasis that cannot be reversed by homeostatic mechanisms alone. We describe how inflammatory signals act on the same cellular functions involved in normal tissue organization and homeostasis in order to coordinate emergency responses to perturbations and ultimately return the system to a homeostatic state. Finally, we consider the hierarchy of homeostatic and inflammatory circuits and the implications for the development of inflammatory diseases.

Innate Immune Cells in the Adipose Tissue in Health and Metabolic Disease

Metabolic disorders, such as obesity, type 2 diabetes mellitus, and nonalcoholic fatty liver disease, are characterized by chronic low-grade tissue and systemic inflammation. During obesity, the adipose tissue undergoes immunometabolic and functional transformation. Adipose tissue inflammation is driven by innate and adaptive immune cells and instigates insulin resistance. Here, we discuss the role of innate immune cells, that is, macrophages, neutrophils, eosinophils, natural killer cells, innate lymphoid type 2 cells, dendritic cells, and mast cells, in the adipose tissue in the healthy (lean) and diseased (obese) state and describe how their function is shaped by the obesogenic microenvironment, and humoral, paracrine, and cellular interactions. Moreover, we particularly outline the role of hypoxia as a central regulator in adipose tissue inflammation. Finally, we discuss the long-lasting effects of adipose tissue inflammation and its potential reversibility through drugs, caloric restriction, or exercise training.

IL-6 as a Mediator of the Association Between Traditional Risk Factors and Future Myocardial Infarction: A Nested Case-Control Study

[Figure: see text].

The modulation of mature dendritic cells from patients with type 1 diabetes using human periodontal ligament stem cells. An in-vitro study

Objective

This in vitro study aimed to investigate whether human periodontal ligament stem cells isolated from impacted third molars can modify the maturation and phenotype of monocyte-derived dendritic cells pulsed with GAD-65 obtained from patients with type 1 diabetes.

Background

Human periodontal ligament stem cells (PDLSCs) have been found to display cell surface marker characteristics similar to bone marrow stromal stem cells (BMSSCs). The immunosuppressive effects on dendritic cells (DCs), T and B cells as well as their low immunogenicity allow the use of PDLSCs in stem cell therapies for autoimmune diseases including type 1 diabetes (T1D). Studies on the immunomodulatory potential of PDLSCs in the context type 1 diabetes are lacking but are therefore worth pursuing.

Methods

CD14 + monocytes isolated from peripheral blood mononuclear cells (PBMNCs) of type 1 diabetic patients were differentiated into immature Dendritic Cells (iDCs) and then maturation was induced to generate Mature Dendritic Cells (mDCs). The mDCs were pulsed with human recombinant GAD-65 and then co-cultured with PDLSCs that were isolated from impacted third molars and characterized. The changes in the levels of differentiation and maturation surface markers on the dendritic cells were analyzed by flow cytometry at the immature state, mature state and after the co-culture experiment. The levels of the secreted cytokines; IL-6, IL-10, and TGF-β were measured by ELISA in cell-free culture supernatant.

Results

PDLSCs exerted an immunosuppressive effect on fully mature dendritic cells from patients with type 1 diabetes. This immunoregulatory property of was apparent by the reduction of all maturation markers including CD80, CD83, CD86, CD40, CD1a, CD209 and HLA-DR. Moreover, there was a detection of high levels of anti-inflammatory cytokines in the co-culture supernatant media including a significant increase in the concentration of IL-6 and TGF-β.

Conclusions

The current in vitro study provides strong evidence that PDLSCs seem to be a very promising source for overcoming the autoimmune destruction seen in T1D as they exerted an immunosuppressive effect on monocyte derived mDCs from patients with T1D. Additional studies should be conducted to further reveal the immunomodulatory and suppressive properties of PDLSCs and their potential use in immunotherapy for this disease.

Muscle-derived interleukin 6 increases exercise capacity by signaling in osteoblasts

Given the numerous health benefits of exercise, understanding how exercise capacity is regulated is a question of paramount importance. Circulating interleukin 6 (IL-6) levels surge during exercise and IL-6 favors exercise capacity. However, neither the cellular origin of circulating IL-6 during exercise nor the means by which this cytokine enhances exercise capacity has been formally established yet. Here we show through genetic means that the majority of circulating IL-6 detectable during exercise originates from muscle and that to increase exercise capacity, IL-6 must signal in osteoblasts to favor osteoclast differentiation and the release of bioactive osteocalcin in the general circulation. This explains why mice lacking the IL-6 receptor only in osteoblasts exhibit a deficit in exercise capacity of similar severity to the one seen in mice lacking muscle-derived IL-6 (mIL-6), and why this deficit is correctable by osteocalcin but not by IL-6. Furthermore, in agreement with the notion that IL-6 acts through osteocalcin, we demonstrate that mIL-6 promotes nutrient uptake and catabolism into myofibers during exercise in an osteocalcin-dependent manner. Finally, we show that the crosstalk between osteocalcin and IL-6 is conserved between rodents and humans. This study provides evidence that a muscle-bone-muscle endocrine axis is necessary to increase muscle function during exercise in rodents and humans.

Olfactory ecto-mesenchymal stem cell-derived exosomes ameliorate murine Sjögren's syndrome by modulating the function of myeloid-derived suppressor cells

Sjögren’s syndrome (SS) is a systemic autoimmune disease characterized by progressive inflammation and tissue damage in salivary glands and lacrimal glands. Our previous studies showed that myeloid-derived suppressor cells (MDSCs) exhibited impaired immunosuppressive function during disease progression in patients with SS and mice with experimental Sjögren’s syndrome (ESS), but it remains unclear whether restoring the function of MDSCs can effectively ameliorate the development of ESS. In this study, we found that murine olfactory ecto-mesenchymal stem cell-derived exosomes (OE-MSC-Exos) significantly enhanced the suppressive function of MDSCs by upregulating arginase expression and increasing ROS and NO levels. Moreover, treatment with OE-MSC-Exos via intravenous injection markedly attenuated disease progression and restored MDSC function in ESS mice. Mechanistically, OE-MSC-Exo-secreted IL-6 activated the Jak2/Stat3 pathway in MDSCs. In addition, the abundant S100A4 in OE-MSC-Exos acted as a key factor in mediating the endogenous production of IL-6 by MDSCs via TLR4 signaling, indicating an autocrine pathway of MDSC functional modulation by IL-6. Taken together, our results demonstrated that OE-MSC-Exos possess therapeutic potential to attenuate ESS progression by enhancing the immunosuppressive function of MDSCs, possibly constituting a new strategy for the treatment of Sjögren’s syndrome and other autoimmune diseases.

Repeated acute stress modulates hepatic inflammation and markers of macrophage polarisation in the rat

Bidirectional communication between the neuroendocrine stress and immune systems permits classically anti-inflammatory glucocorticoids to exert pro-inflammatory effects in specific cells and tissues. Liver macrophages/Kupffer cells play a crucial role in initiating inflammatory cascades mediated by the release of pro-inflammatory cytokines following tissue injury. However, the effects of repeated acute psychological stress on hepatic inflammatory phenotype and macrophage activation state remains poorly understood. We have utilised a model of repeated acute stress in rodents to observe the changes in hepatic inflammatory phenotype, including anti-inflammatory vitamin D status, in addition to examining markers of classically and alternatively-activated macrophages. Male Wistar rats were subjected to control conditions or 6 h of restraint stress applied for 1 or 3 days (n = 8 per group) after which plasma concentrations of stress hormone, enzymes associated with liver damage, and vitamin D status were examined, in addition to hepatic expression of pro- and anti-inflammatory markers. Stress increased glucocorticoids and active vitamin D levels in addition to expression of glucocorticoid alpha/beta receptor, whilst changes in circulating hepatic enzymes indicated sustained liver damage. A pro-inflammatory response was observed in liver tissues following stress, and inducible nitric oxide synthase being observed within hepatic macrophage/Kupffer cells. Together, this suggests that stress preferentially induces a pro-inflammatory response in the liver.

Nicotine' actions on energy balance: Friend or foe?

Obesity has reached pandemic proportions and is associated with severe comorbidities, such as type 2 diabetes mellitus, hepatic and cardiovascular diseases, and certain cancer types. However, the therapeutic options to treat obesity are limited. Extensive epidemiological studies have shown a strong relationship between smoking and body weight, with non-smokers weighing more than smokers at any age. Increased body weight after smoking cessation is a major factor that interferes with their attempts to quit smoking. Numerous controlled studies in both humans and rodents have reported that nicotine, the main bioactive component of tobacco, exerts a marked anorectic action. Furthermore, nicotine is also known to modulate energy expenditure, by regulating the thermogenic activity of brown adipose tissue (BAT) and the browning of white adipose tissue (WAT), as well as glucose homeostasis. Many of these actions occur at central level, by controlling the activity of hypothalamic neuropeptide systems such as proopiomelanocortin (POMC), or energy sensors such as AMP-activated protein kinase (AMPK). However, direct impact of nicotine on metabolic tissues, such as BAT, WAT, liver and pancreas has also been described. Here, we review the actions of nicotine on energy balance. The relevance of this interaction is interesting, because considering the restricted efficiency of obesity treatments, a possible complementary approach may focus on compounds with known pharmacokinetic profile and pharmacological actions, such as nicotine or nicotinic acetylcholine receptors signaling.

Blocking IL-6/GP130 Signaling Inhibits Cell Viability/Proliferation, Glycolysis, and Colony Forming Activity in Human Pancreatic Cancer Cells

BACKGROUND

Elevated production of the pro-inflammatory cytokine interleukin-6 (IL-6) and dysfunction of IL-6 signaling promotes tumorigenesis and are associated with poor survival outcomes in multiple cancer types. Recent studies showed that the IL-6/GP130/STAT3 signaling pathway plays a pivotal role in pancreatic cancer development and maintenance.

OBJECTIVE

We aim to develop effective treatments through inhibition of IL-6/GP130 signaling in pancreatic cancer.

METHODS

The effects on cell viability and cell proliferation were measured by MTT and BrdU assays, respectively. The effects on glycolysis was determined by cell-based assays to measure lactate levels. Protein expression changes were evaluated by western blotting and immunoprecipitation. siRNA transfection was used to knock down estrogen receptor α gene expression. Colony forming ability was determined by colony forming cell assay.

RESULTS

We demonstrated that IL-6 can induce pancreatic cancer cell viability/proliferation and glycolysis. We also showed that a repurposing FDA-approved drug bazedoxifene could inhibit the IL-6/IL-6R/GP130 complexes. Bazedoxifene also inhibited JAK1 binding to IL-6/IL-6R/GP130 complexes and STAT3 phosphorylation. In addition, bazedoxifene impeded IL-6 mediated cell viability/ proliferation and glycolysis in pancreatic cancer cells. Consistently, other IL-6/GP130 inhibitors SC144 and evista showed similar inhibition of IL-6 stimulated cell viability, cell proliferation and glycolysis. Furthermore, all three IL-6/GP130 inhibitors reduced the colony forming ability in pancreatic cancer cells.

CONCLUSION

Our findings demonstrated that IL-6 stimulates pancreatic cancer cell proliferation, survival and glycolysis, and supported persistent IL-6 signaling is a viable therapeutic target for pancreatic cancer using IL-6/GP130 inhibitors.

Interleukin 6-independent metabolic reprogramming as a driver of cancer-related fatigue

Fatigue is a common and debilitating symptom of cancer with few effective interventions. Cancer-related fatigue (CRF) is often associated with increases in inflammatory cytokines, however inflammation may not be requisite for this symptom, suggesting other biological mediators also play a role. Because tumors are highly metabolically active and can amplify their energetic toll via effects on distant organs, we sought to determine whether CRF could be explained by metabolic competition exacted by the tumor. We used a highly metabolically active murine E6/E7/hRas model of head and neck cancer for this purpose. Mice with or without tumors were submitted to metabolic constraints in the form of voluntary wheel running or acute overnight fasting and their adaptive behavioral (home cage activity and fasting-induced wheel running) and metabolic responses (blood glucose, ketones, and liver metabolic gene expression) were monitored. We found that the addition of running wheel was necessary to measure activity loss, used as a surrogate for fatigue in this study. Tumor-bearing mice engaged in wheel running showed a decrease in blood glucose levels and an increase in lactate accumulation in the skeletal muscle, consistent with inhibition of the Cori cycle. These changes were associated with gene expression changes in the livers consistent with increased glycolysis and suppressed gluconeogenesis. Fasting also decreased blood glucose in tumor-bearing mice, without impairing glucose or insulin tolerance. Fasting-induced increases in wheel running and ketogenesis were suppressed by tumors, which was again associated with a shift from gluconeogenic to glycolytic metabolism in the liver. Blockade of IL-6 signaling with a neutralizing antibody failed to recover any of the behavioral or metabolic outcomes. Taken together, these data indicate that metabolic competition between the tumor and the rest of the organism is an important component of fatigue and support the hypothesis of a central role for IL-6-independent hepatic metabolic reprogramming in the pathophysiology of CRF.

Origin and Function of Stress-Induced IL-6 in Murine Models

Acute psychological stress has long been known to decrease host fitness to inflammation in a wide variety of diseases, but how this occurs is incompletely understood. Using mouse models, we show that interleukin-6 (IL-6) is the dominant cytokine inducible upon acute stress alone. Stress-inducible IL-6 is produced from brown adipocytes in a beta-3-adrenergic-receptor-dependent fashion. During stress, endocrine IL-6 is the required instructive signal for mediating hyperglycemia through hepatic gluconeogenesis, which is necessary for anticipating and fueling "fight or flight" responses. This adaptation comes at the cost of enhancing mortality to a subsequent inflammatory challenge. These findings provide a mechanistic understanding of the ontogeny and adaptive purpose of IL-6 as a bona fide stress hormone coordinating systemic immunometabolic reprogramming. This brain-brown fat-liver axis might provide new insights into brown adipose tissue as a stress-responsive endocrine organ and mechanistic insight into targeting this axis in the treatment of inflammatory and neuropsychiatric diseases.

Effects of Aerobic Exercise Protocol on Genes Related to Insulin Resistance and Inflammation in the Pancreas of ob/ob Mice with NAFLD

Purpose

To evaluate the effect of 8 weeks of aerobic training on insulin resistance and inflammatory response in obese mice (ob/ob) with NAFLD.

Materials and Methods

Male ob/ob mice were randomly divided into sedentary (n=7) and trained (n=7) groups. Aerobic training consisted of 5 weekly sessions, 60 min per session at 60% of the maximum speed of the running test. Hepatic and pancreatic samples were collected to evaluate histological features and gene expression associated with insulin resistance and inflammatory response after 8-week experiment protocol. RNA was performed by TRIzol^®. PCR experiments were performed using the Rotor-Gene RG-3000. Parametric data were assessed by t-test, one-way ANOVA and Bonferroni test for multiple comparisons. Non-parametric data were assessed by the Mann-Whitney tests with Dunn's post-test of multiple comparisons. Histological analysis was assessed by chi-square test with Fisher's exact test. Significant variables were considered when p<0.05. All the analyses were performed by GraphPad Prism V6.0 software (GraphPad Software Inc.).

Results

Reductions in bodyweight (p = 0.008), weight evolution (p = 0.03), food intake (p <0.0001) and fat content were observed in trained group. Moreover, the trained group showed better results in peak velocity (p=0.03) physical effort tolerance (p=0.006) and distance (p=0.01). Gene expression showed differences in IL-10 (p=0.03) and GLUT-2 (p=0.03) in hepatic analysis, between groups. Pancreatic gene expression showed difference between groups in IRS-2 (p=0.004), GLUT-2 (p=0.03) and IL-10 (p=0.008) analysis. Also, the trained group showed lower values for interlobular fat and inflammatory infiltrate in histological analysis when compared to sedentary animals.

Conclusion

An 8-week physical training protocol was able to attenuate bodyweight gain, food intake and generate positive effects on gene expression related to insulin resistance and inflammation in both liver and pancreas of ob/ob mice.

IL-6 trans-Signaling Impairs Sprouting Angiogenesis by Inhibiting Migration, Proliferation and Tube Formation of Human Endothelial Cells

Sprouting angiogenesis is the formation of new capillaries from existing vessels in response to tissue hypoxia due to growth/development, repair/healing, and also chronic inflammation. In this study, we aimed to elucidate the effect of IL-6, a pleiotropic cytokine with both pro-inflammatory and anti-inflammatory functions, in regulating the sprouting angiogenic response of endothelial cells (ECs). We found that activation of IL-6 trans-signaling inhibited the migration, proliferation, and tube formation ability of ECs. In addition, inhibition of the autocrine IL-6 classic-signaling by depleting endogenous IL-6 from ECs impaired their tube formation ability. At the molecular level, we found that IL-6 trans-signaling in ECs upregulated established endogenous anti-angiogenic factors such as CXCL10 and SERPINF1 while at the same time downregulated known endogenous pro-angiogenic factors such as cKIT and CXCL8. Furthermore, prior activation of ECs by IL-6 trans-signaling alters their response to vascular endothelial growth factor-A (VEGF-A), causing an increased p38, but decreased Erk1/2 phosphorylation. Collectively, our data demonstrated the dual facets of IL-6 in regulating the sprouting angiogenic function of ECs. In addition, we shed light on molecular mechanisms behind the IL-6 trans-signaling mediated impairment of endothelial sprouting angiogenic response.

Metabolic Inflammation-A Role for Hepatic Inflammatory Pathways as Drivers of Comorbidities in Nonalcoholic Fatty Liver Disease?

Nonalcoholic fatty liver disease (NAFLD) is a global and growing health concern. Emerging evidence points toward metabolic inflammation as a key process in the fatty liver that contributes to multiorgan morbidity. Key extrahepatic comorbidities that are influenced by NAFLD are type 2 diabetes, cardiovascular disease, and impaired neurocognitive function. Importantly, the presence of nonalcoholic steatohepatitis and advanced hepatic fibrosis increase the risk for systemic comorbidity in NAFLD. Although the precise nature of the crosstalk between the liver and other organs has not yet been fully elucidated, there is emerging evidence that metabolic inflammation-in part, emanating from the fatty liver-is the engine that drives cellular dysfunction, cell death, and deleterious remodeling within various body tissues. This review describes several inflammatory pathways and mediators that have been implicated as links between NAFLD and type 2 diabetes, cardiovascular disease, and neurocognitive decline.

Adipose Tissue Distribution, Inflammation and Its Metabolic Consequences, Including Diabetes and Cardiovascular Disease

Adipose tissue plays essential roles in maintaining lipid and glucose homeostasis. To date several types of adipose tissue have been identified, namely white, brown, and beige, that reside in various specific anatomical locations throughout the body. The cellular composition, secretome, and location of these adipose depots define their function in health and metabolic disease. In obesity, adipose tissue becomes dysfunctional, promoting a pro-inflammatory, hyperlipidemic and insulin resistant environment that contributes to type 2 diabetes mellitus (T2DM). Concurrently, similar features that result from adipose tissue dysfunction also promote cardiovascular disease (CVD) by mechanisms that can be augmented by T2DM. The mechanisms by which dysfunctional adipose tissue simultaneously promote T2DM and CVD, focusing on adipose tissue depot-specific adipokines, inflammatory profiles, and metabolism, will be the focus of this review. The impact that various T2DM and CVD treatment strategies have on adipose tissue function and body weight also will be discussed.

Regulation of adipose tissue inflammation by interleukin 6

Obesity is associated with a chronic state of low-grade inflammation and progressive tissue infiltration by immune cells and increased expression of inflammatory cytokines. It is established that interleukin 6 (IL6) regulates multiple aspects of metabolism, including glucose disposal, lipolysis, oxidative metabolism, and energy expenditure. IL6 is secreted by many tissues, but the role of individual cell types is unclear. We tested the role of specific cells using a mouse model with conditional expression of the Il6 gene. We found that IL6 derived from adipocytes increased, while IL6 derived from myeloid cells and muscle suppressed, macrophage infiltration of adipose tissue. These opposite actions were associated with a switch of IL6 signaling from a canonical mode (myeloid cells) to a noncanonical trans-signaling mode (adipocytes and muscle) with increased expression of the ADAM10/17 metalloprotease that promotes trans-signaling by the soluble IL6 receptor α. Collectively, these data demonstrate that the source of IL6 production plays a major role in the physiological regulation of metabolism.