The Gordian Knot of dysbiosis, obesity and NAFLD

The role of faecal microbiota transplantation in chronic noncommunicable disorders

The gut microbiome plays a key role in influencing several pathways and functions involved in human health, including metabolism, protection against infection, and immune regulation. Perturbation of the gut microbiome is recognised as a pathogenic factor in several gastrointestinal and extraintestinal disorders, and is increasingly considered as a therapeutic target in these conditions. Faecal microbiota transplantation (FMT) is the transfer of the microbiota from healthy screened stool donors into the gut of affected patients, and is a well-established and highly effective treatment for recurrent Clostridioides difficile infection. Despite the mechanisms of efficacy of FMT not being fully understood, it has been investigated in several chronic noncommunicable disorders, with variable results. This review aims to give an overview of mechanisms of efficacy of FMT in chronic noncommunicable disorders, and to paint the current landscape of its investigation in these medical conditions, including inflammatory bowel disease (IBD), chronic liver disorders, and also extraintestinal autoimmune conditions.

From-Toilet-to-Freezer: A Review on Requirements for an Automatic Protocol to Collect and Store Human Fecal Samples for Research Purposes

The composition, viability and metabolic functionality of intestinal microbiota play an important role in human health and disease. Studies on intestinal microbiota are often based on fecal samples, because these can be sampled in a non-invasive way, although procedures for sampling, processing and storage vary. This review presents factors to consider when developing an automated protocol for sampling, processing and storing fecal samples: donor inclusion criteria, urine-feces separation in smart toilets, homogenization, aliquoting, usage or type of buffer to dissolve and store fecal material, temperature and time for processing and storage and quality control. The lack of standardization and low-throughput of state-of-the-art fecal collection procedures promote a more automated protocol. Based on this review, an automated protocol is proposed. Fecal samples should be collected and immediately processed under anaerobic conditions at either room temperature (RT) for a maximum of 4 h or at 4 °C for no more than 24 h. Upon homogenization, preferably in the absence of added solvent to allow addition of a buffer of choice at a later stage, aliquots obtained should be stored at either -20 °C for up to a few months or -80 °C for a longer period-up to 2 years. Protocols for quality control should characterize microbial composition and viability as well as metabolic functionality.

Potential tactics with certain gut microbiota for the treatment of unresectable hepatocellular carcinoma

Hepatocellular carcinoma (HCC) constitutes an extremely malignant form of primary liver cancer. Intricate connections linking to the immune system might be associated with the pathogenesis of HCC. Meanwhile, immunotherapy with immune checkpoint inhibitors has been established to be a favorable therapeutic possibility for advanced HCC. Although curative opportunities for advanced HCC are restricted, the immune checkpoint immunotherapy has developed as the main choice for treating HCC. However, patients with metabolic-associated fatty liver disease (MAFLD)-linked HCC might be less likely to benefit from the immunotherapy alone. The limitation of the effect of the immunotherapy might be owing to the impaired T cell activation in MAFLD patients, which could be well explained by a dysfunctional gut-liver axis. Gut microbiota and their metabolites including several bile acids could contribute to modulating the responses of the immune checkpoint immunotherapy. Roles of gut microbiota in the development of cancers have expected great interest in the latest studies. Here, an interplay between the gut and liver has been presented, which might suggest to affect the efficacy of immune checkpoint immunotherapy against HCC.

In Vitro Screening for Probiotic Properties of Lactobacillus and Bifidobacterium Strains in Assays Relevant for Non-Alcoholic Fatty Liver Disease Prevention

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial metabolic disorder that poses health challenges worldwide and is expected to continue to rise dramatically. NAFLD is associated with metabolic syndrome, type 2 diabetes mellitus, and impaired gut health. Increased gut permeability, caused by disturbance of tight junction proteins, allows passage of damaging microbial components that, upon reaching the liver, have been proposed to trigger the release of inflammatory cytokines and generate cellular stress. A growing body of research has suggested the utilization of targeted probiotic supplements as a preventive therapy to improve gut barrier function and tight junctions. Furthermore, specific microbial interactions and metabolites induce the secretion of hormones such as GLP-1, resulting in beneficial effects on liver health. To increase the likelihood of finding beneficial probiotic strains, we set up a novel screening platform consisting of multiple in vitro and ex vivo assays for the screening of 42 bacterial strains. Analysis of transepithelial electrical resistance response via co-incubation of the 42 bacterial strains with human colonic cells (Caco-2) revealed improved barrier integrity. Then, strain-individual metabolome profiling was performed revealing species-specific clusters. GLP-1 secretion assay with intestinal secretin tumor cell line (STC-1) found at least seven of the strains tested capable of enhancing GLP-1 secretion in vitro. Gene expression profiling in human biopsy-derived intestinal organoids was performed using next generation sequencing transcriptomics post bacterial co-incubation. Here, different degrees of immunomodulation by the increase in certain cytokine and chemokine transcripts were found. Treatment of mouse primary hepatocytes with selected highly produced bacterial metabolites revealed that indole metabolites robustly inhibited de novo lipogenesis. Collectively, through our comprehensive bacterial screening pipeline, not previously ascribed strains from both Lactobacillus and Bifidobacterium genera were proposed as potential probiotics based on their ability to increase epithelial barrier integrity and immunity, promote GLP-1 secretion, and produce metabolites relevant to liver health.

New uses for an old remedy: Digoxin as a potential treatment for steatohepatitis and other disorders

Repurposing of the widely available and relatively cheap generic cardiac gly-coside digoxin for non-cardiac indications could have a wide-ranging impact on the global burden of several diseases. Over the past several years, there have been significant advances in the study of digoxin pharmacology and its potential non-cardiac clinical applications, including anti-inflammatory, antineoplastic, metabolic, and antimicrobial use. Digoxin holds promise in the treatment of gastrointestinal disease, including nonalcoholic steatohepatitis and alcohol-associated steatohepatitis as well as in obesity, cancer, and treatment of viral infections, among other conditions. In this review, we provide a summary of the clinical uses of digoxin to date and discuss recent research on its emerging applications.

Faecal Microbiota Transplantation, Paving the Way to Treat Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is currently the most prevalent cause of chronic liver disease (CLD). Currently, the only therapeutic recommendation available is a lifestyle change. However, adherence to this approach is often difficult to guarantee. Alteration of the microbiota and an increase in intestinal permeability seem to be key in the development and progression of NAFLD. Therefore, the manipulation of microbiota seems to provide a promising therapeutic strategy. One way to do so is through faecal microbiota transplantation (FMT). Here, we summarize the key aspects of FMT, detail its current indications and highlight the most recent advances in NAFLD.

Extrahepatic morbidities and mortality of NAFLD: an umbrella review of meta-analyses

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has reached pandemic proportions currently and may contribute to multiple extrahepatic outcomes.

AIM

To comprehensively summarise evidence of associations between NAFLD and risk of extrahepatic outcomes.

METHODS

We conducted an umbrella review. We searched PubMed, Web of Science and Cochrane database from inception to 27 November 2021.

RESULTS

We included 22 meta-analyses with 374 original studies in our analysis. Subjects with NAFLD had an increased risk of mortality, multiple cardiovascular complications, extrahepatic cancers, diabetes and chronic kidney disease (CKD) than those without NAFLD. Excess risks of several other extrahepatic outcomes including hypothyroidism, urolithiasis, gastro-oesophageal reflux disease, gallstones, depression and worse maternal and foetal outcomes were also observed in this population. However, associations were not significant for prostate cancer, female organ genital cancer, haematological cancer, diabetic retinopathy or osteoporotic fracture. The risks of CVD, diabetes and CKD were similar in obese and non-obese patients. Most associations were heterogeneous across regions; significantly, Europeans with NAFLD were more prone to all-cause mortality than North Americans. The certainty of evidence was graded from only very low to moderate as all included studies were observational.

CONCLUSIONS

Patients with NAFLD are at heightened risk of extrahepatic outcomes. However, the certainty of evidence is only from very low to moderate. Further studies at low risk of bias are required to support the evidence and elucidate any causal associations.

Prolonged Use of Proton Pump Inhibitors and Risk of Type 2 Diabetes: Results From a Large Population-Based Nested Case-Control Study

CONTEXT

It is still debated whether prolonged use of proton pump inhibitors (PPIs) might affect metabolic health.

OBJECTIVE

To investigate the relationship between prolonged use of PPIs and the risk of developing diabetes.

METHODS

We performed a case-control study nested into a cohort of 777 420 patients newly treated with PPIs between 2010 and 2015 in Lombardy, Italy. A total of 50 535 people diagnosed with diabetes until 2020 were matched with an equal number of controls that were randomly selected from the cohort members according to age, sex, and clinical status. Exposure to treatment with PPIs was assessed in case-control pairs based on time of therapy. A conditional logistic regression model was fitted to estimate the odds ratios and 95% CIs for the exposure-outcome association, after adjusting for several covariates. Sensitivity analyses were performed to evaluate the robustness of our findings.

RESULTS

Compared with patients who used PPIs for < 8 weeks, higher odds of diabetes of 19% (95% CI, 15-24), 43% (38-49), and 56% (49-64) were observed among those who used PPIs for between 8 weeks and 6 months, 6 months and 2 years, and > 2 years, respectively. The results were consistent when analyses were stratified according to age, sex, and clinical profile, with higher odds ratios being found in younger patients and those with worse clinical complexity. Sensitivity analyses revealed that the association was consistent and robust.

CONCLUSIONS

Regular and prolonged use of PPIs is associated with a higher risk of diabetes. Physicians should therefore avoid unnecessary prescription of this class of drugs, particularly for long-term use.

Pharmacodynamic Evaluation of the Gexia Zhuyu Decoction in the Treatment of NAFLD and the Molecular Mechanism Underlying the TRPM4 Pathway Regulation

Nonalcoholic fatty liver disease (NAFLD) is a clinicopathological syndrome of abnormal lipid deposition in the liver mediated by nonalcohol intake. The Gexia Zhuyu decoction, a classic traditional Chinese medicine compound, is widely used in the clinical treatment of NAFLD. However, its specific efficacy and underlying mechanisms have not been elucidated yet. This study aimed to quantitatively evaluate the efficacy of the Gexia Zhuyu decoction using pharmacodynamics and to explore its molecular mechanisms in conjunction with proteomics. High-fat diets and methionine choline-deficient diets were used to induce various NAFLD progression stages in mouse models. The effects of oral Gexia Zhuyu decoction administration on NAFLD were evaluated by measuring the serum and liver indicators of the treated mice before and after drug intervention and by comparing the changes in liver tissue. Liver TRPM4 mRNA and protein levels were measured using reverse transcription-polymerase chain reaction and Western blotting, respectively. Experimental data showed that serum ALT, AST, and liver triglyceride (TG) levels in each disease stage group of drug intervention mice decreased, and high-density lipoprotein (HDL) and superoxide dismutase (SOD) levels increased. Liver TG levels decreased after drug intervention in the liver fibrosis mice, but serum TG levels increased. Furthermore, cellular fatty changes, inflammatory changes, and fibrous tissue proliferation were all relieved. The TRPM4 protein and mRNA levels in the liver tissue were decreased, and the microRNA (miRNA)-24 expression was increased. The Gexia Zhuyu decoction has a clear therapeutic effect at each stage of NAFLD. It likely acts by altering miRNA-24 expression and regulating the target TRPM4 protein pathway to achieve NAFLD treatment.

Longitudinal Analysis of the Intestinal Microbiota in the Obese Mangalica Pig Reveals Alterations in Bacteria and Bacteriophage Populations Associated With Changes in Body Composition and Diet

Due to its immunomodulatory potential, the intestinal microbiota has been implicated as a contributing factor in the development of the meta-inflammatory state that drives obesity-associated insulin resistance and type 2 diabetes. A better understanding of this link would facilitate the development of targeted treatments and therapies to treat the metabolic complications of obesity. To this end, we validated and utilized a novel swine model of obesity, the Mangalica pig, to characterize changes in the gut microbiota during the development of an obese phenotype, and in response to dietary differences. In the first study, we characterized the metabolic phenotype and gut microbiota in lean and obese adult Mangalica pigs. Obese or lean groups were created by allowing either ad libitum (obese) or restricted (lean) access to a standard diet for 54 weeks. Mature obese pigs were significantly heavier and exhibited 170% greater subcutaneous adipose tissue mass, with no differences in muscle mass compared to their lean counterparts. Obese pigs displayed impaired glucose tolerance and hyperinsulinemia following oral glucose challenge, indicating that a metabolic phenotype also manifested with changes in body composition. Consistent with observations in human obesity, the gut microbiota of obese pigs displayed altered bacterial composition. In the second study, we characterized the longitudinal changes in the gut microbiota in response to diet and aging in growing Mangalica pigs that were either limit fed a standard diet, allowed ad libitum access to a standard diet, or allowed ad libitum access to a high fat-supplemented diet over an 18-week period. As expected, weight gain was highest in pigs fed the high fat diet compared to ad libitum and limit fed groups. Furthermore, the ad libitum and high fat groups displayed significantly greater adiposity consistent with the development of obesity relative to the limit fed pigs. The intestinal microbiota was generally resilient to differences in dietary intake (limit fed vs ad libitum), though changes in the microbiota of pigs fed the high fat diet mirrored changes observed in mature obese pigs during the first study. This is consistent with the link observed between the microbiota and adiposity. In contrast to intestinal bacterial populations, bacteriophage populations within the gut microbiota responded rapidly to differences in diet, with significant compositional changes in bacteriophage genera observed between the dietary treatment groups as pigs aged. These studies are the first to describe the development of the intestinal microbiota in the Mangalica pig, and are the first to provide evidence that changes in body composition and dietary conditions are associated with changes in the microbiome of this novel porcine model of obesity.

Metabolic drivers of non-alcoholic fatty liver disease

BACKGROUND

The incidence of non-alcoholic fatty liver disease (NAFLD) is rapidly increasing worldwide parallel to the global obesity epidemic. NAFLD encompasses a range of liver pathologies and most often originates from metabolically driven accumulation of fat in the liver, or non-alcoholic fatty liver (NAFL). In a subset of NAFL patients, the disease can progress to non-alcoholic steatohepatitis (NASH), which is a more severe form of liver disease characterized by hepatocyte injury, inflammation, and fibrosis. Significant progress has been made over the past decade in our understanding of NASH pathogenesis, but gaps remain in our mechanistic knowledge of the precise metabolic triggers for disease worsening.

SCOPE OF REVIEW

The transition from NAFL to NASH likely involves a complex constellation of multiple factors intrinsic and extrinsic to the liver. This review focuses on early metabolic events in the establishment of NAFL and initial stages of NASH. We discuss the association of NAFL with obesity as well as the role of adipose tissue in disease progression and highlight early metabolic drivers implicated in the pathological transition from hepatic fat accumulation to steatohepatitis.

MAJOR CONCLUSIONS

The close association of NAFL with features of metabolic syndrome highlight plausible mechanistic roles for adipose tissue health and the release of lipotoxic lipids, hepatic de novo lipogenesis (DNL), and disruption of the intestinal barrier in not only the initial establishment of hepatic steatosis, but also in mediating disease progression. Human genetic variants linked to NASH risk to date are heavily biased toward genes involved in the regulation of lipid metabolism, providing compelling support for the hypothesis that NASH is fundamentally a metabolic disease.

The interaction between gut microbiota and flavonoid extract from Smilax glabra Roxb. and its potent alleviation of fatty liver

Fatty liver is associated with intestinal microbiota dysbiosis and low-grade chronic inflammation. Herein we report the interaction of the flavonoid extract from Smilax glabra Roxb. (FSGR) with gut microbiota. Then, FSGR's function of modulating microbiota in a rat model of high-fat diet (HFD) induced fatty liver has been explored. These investigations indicated that the main compound in FSGR, such as astilbin and its isomers, could be metabolized to aglycone, while further splitting resulted in some phenolic acid compounds through a redox reaction. The data obtained clearly showed that FSGR not only alleviated the steatosis degree of liver cells and modulated the contents of short chain fatty acids (SCFAs) in the intestinal tract, but also reversed gut dysbiosis induced by HFD as prognosticated by the decreased ratio of Firmicutes/Bacteroidetes (F/B) and altered gene expression. The results demonstrated that FSGR probably could be used as a prebiotic agent to impede gut dysbiosis and fatty liver-related metabolic disorders.

The Impact of the NLRP3 Pathway in the Pathogenesis of Non-Alcoholic Fatty Liver Disease and Alcohol-Related Liver Disease

The presence of hepatic steatosis and inflammation is increasingly associated with both metabolic and alcohol-related liver conditions. Both are on the increase globally and, apart from liver transplantation, there are no licensed therapies that target the full complement of disease features. The presence of some shared pathogenic mechanisms and histological features in NAFLD and ALD suggests that it may be possible to develop markers for prognostication or staging, or indeed new therapeutic tools to treat both conditions. One such example of an approach exists in the form of the NACHT-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome pathway. Activation of the NLRP3 inflammasome results in hepatocyte pyroptosis, persistence, and amplification of liver inflammation and activation of profibrogenic signaling cascades. Thus, targeting elements of the pathway in NAFLD and ALD may provide a tractable route to pharmacological therapy. In this review, we summarize the contribution of this inflammasome to disease and review the current options for therapy.

The Role of Gut Microbiota in Duodenal-Jejunal Bypass Surgery-Induced Improvement of Hepatic Steatosis in HFD-Fed Rats

Bariatric surgery including duodenal-jejunal bypass surgery (DJB) improves insulin sensitivity and reduces obesity-associated inflammation. However, the underlying mechanism for such an improvement is still incompletely understood. Our objective was to investigate the role of the gut microbiota in DJB-associated improvement of hepatic steatosis in high fat diet (HFD)-fed rats. To study this, hepatic steatosis was induced in male adult Sprague-Dawley rats by feeding them with a 60% HFD. At 8 weeks after HFD feeding, the rats were subjected to either DJB or sham operation. HFD was resumed 1 week after the surgery for 3 more weeks. In additional groups of animals, feces were collected from HFD-DJB rats at 2 weeks after DJB. These feces were then transplanted to HFD-fed rats without DJB at 8 weeks after HFD feeding. Hepatic steatosis and fecal microbiota were analyzed at 4 weeks after surgery or fecal transplantation. Our results showed that DJB alleviated hepatic steatosis in HFD-fed rats. Fecal microbiota analysis showed that HFD-fed and standard diet-fed rats clustered differently. DJB induced substantial compositional changes in the gut microbiota. The fecal microbiota of HFD-fed rats received fecal transplant from DJB rats overlapped with that of HFD-DJB rats. Treatment of rats with HFD-induced liver lesions by fecal transplant from DJB-operated HFD-fed rats also attenuated hepatic steatosis. Thus, alterations in the gut microbiota after DJB surgery are sufficient to attenuate hepatic steatosis in HFD-fed rats. Targeting the gut microbiota could be a promising approach for preventing or treating human NAFLD.

Bone morphogenetic protein 4 (BMP4) promotes hepatic glycogen accumulation and reduces glucose level in hepatocytes through mTORC2 signaling pathway

Liver is an important organ for regulating glucose and lipid metabolism. Recent studies have shown that bone morphogenetic proteins (BMPs) may play important roles in regulating glucose and lipid metabolism. In our previous studies, we demonstrated that BMP4 significantly inhibits hepatic steatosis and lowers serum triglycerides, playing a protective role against the progression of non-alcoholic fatty liver disease (NAFLD). However, the direct impact of BMP4 on hepatic glucose metabolism is poorly understood. Here, we investigated the regulatory roles of BMP4 in hepatic glucose metabolism. Through a comprehensive analysis of the 14 types of BMPs, we found that BMP4 was one of the most potent BMPs in promoting hepatic glycogen accumulation, reducing the level of glucose in hepatocytes and effecting the expression of genes related to glucose metabolism. Mechanistically, we demonstrated that BMP4 reduced the hepatic glucose levels through the activation of mTORC2 signaling pathway in vitro and in vivo. Collectively, our findings strongly suggest that BMP4 may play an essential role in regulating hepatic glucose metabolism. This knowledge should aid us to understand the molecular pathogenesis of NAFLD, and may lead to the development of novel therapeutics by exploiting the inhibitory effects of BMPs on hepatic glucose and lipid metabolism.

Phenotyping non-alcoholic fatty liver disease by the gut microbiota: Ready for prime time?

BACKGROUND AND AIM

Several studies observed alterations in the gut microbiota in patients with non-alcoholic fatty liver disease (NAFLD). However, analyzed patient populations and methods strongly differ among these studies. The aim of this study was to prove the reproducibility of published results and to provide a detailed overview of all findings in our NAFLD cohort using next generation sequencing methods.

METHODS

The individual taxonomic microbiota composition of fecal samples from 90 NAFLD patients and 21 healthy controls was analyzed using 16S rRNA gene sequencing. Study participants were grouped according to their disease stage and compared regarding their gut microbiota composition. Studies were identified from PubMed listed publications, and the results were compared with the findings in our cohort.

RESULTS

Results from 13 identified studies were compared with our data. A decreased abundance of the Bacteroidetes and Ruminococcaceae as well as an increased abundance of Lactobacillaceae and Veillonellaceae and Dorea were the most frequently reported changes among NAFLD patients in 4/13, 5/13, 4/13, 2/13, and 3/13 studies, respectively. Even though these alterations in the gut microbiota composition were also observed in our patient cohort, the majority of published differences could not be reproduced, neither in our own nor in other NAFLD cohort studies.

CONCLUSION

Despite repeatedly reproduced abundance patterns of specific bacteria, the heterogeneous study results did not reveal a consistent disease specific gut microbiota signature. Further prospective studies with homogenous patient cohorts and standardized methods are necessary to phenotype NAFLD by the gut microbiota.

Is a healthy microbiome responsible for lower mortality in COVID-19?

The novel severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) is the cause of an ongoing pandemic with significant case fatality ratio (CFR) worldwide. Although SARS-CoV-2 primarily causes respiratory infection by binding to ACE2 receptors present on alveolar epithelial cells, studies have been published linking the disease to the small intestine enterocytes and its microbiome. Dysbiosis of microbiome, mainly intestinal and lung, can affect the course of the disease. Environmental factors, such as reduced intake of commensal bacteria from the environment or their products in the diet, play an important role in microbiome formation, which can significantly affect the immune response. In elderly, obese or chronically ill people, the microbiota is often damaged. Therefore, we speculate that a good microbiome may be one of the factors responsible for lower CFR from the coronavirus disease 2019 (COVID-19). An approach using tailored nutrition and supplements known to improve the intestinal microbiota and its immune function might help minimize the impact of the disease at least on people at higher risk from coronavirus.

Nonalcoholic fatty liver disease and type 2 diabetes: pathophysiological mechanisms shared between the two faces of the same coin

The pathophysiological mechanisms underlying the close relationship between nonalcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM) are multiple, complex and only partially known. The purpose of this paper was to review the current knowledge of these mechanisms in a unified manner. Subjects with NAFLD and T2DM have established insulin resistance (IR), which exacerbates the two comorbidities. IR worsens NAFLD by increasing the accumulation of free fatty acids (FFAs) in the liver. This occurs due to an increase in the influx of FFAs from peripheral adipose tissue by the activation of hormone-sensitive lipase. In addition, there is de novo increased lipogenesis, a transcription factor, the sterols regulatory element-binding transcription factor 1c (SREBP-1c), which activates the expression of several genes strongly promotes lipogenesis by the liver and facilitate storage of triglycerides. Lipids accumulation in the liver induces a chronic stress in the endoplasmic reticulum of the hepatocytes. Genome-wide association studies have identified genetic variants associated with NAFLD severity, but unrelated to IR. In particular, the alteration of patatin-like phospholipase domain-containing protein 3 contributes to the susceptibility to NAFLD. Furthermore, the lipotoxicity of ceramides and diacylglycerol, well known in T2DM, triggers a chronic inflammatory process favoring the progression from hepatic steatosis to steatohepatitis. Reactive oxygen species produced by mitochondrial dysfunction trigger both liver inflammation and beta-cells damage, promoting the progression of both NAFLD and T2DM. The close association between NAFLD and T2DM is bidirectional, as T2DM may trigger both NAFLD onset and its progression, but NAFLD itself may contribute to the development of IR and T2DM. Future studies on the mechanisms will have to deepen the knowledge of the interaction between the two pathologies and should allow the identification of new therapeutic targets for the treatment of NAFLD, currently substantially absent.

The influence of probiotics on bile acids in diseases and aging

Recent evidence indicates the use of probiotics in the prevention and treatment of diseases. Probiotics are capable of changing the gut microbiota composition and bile acid synthesis to elicit health benefits such as cholesterol-lowering, weight reduction, and improving insulin sensitivity. The aging population is prone to develop diseases because of their decreased physiological and biological systems. Probiotics are one of the promising supplements that may potentially counteract these detrimental effects. This review will discuss the influence of probiotics on bile acids in different populations-the elderly, obese individuals, and those with hypercholesterolemia, type 2 diabetes, hypertension, and non-alcoholic fatty liver disease.

The effect of synbiotic supplementation on anthropometric indices, appetite, and constipation in people with hypothyroidism: A randomized, double-blind, placebo-controlled trial

Hypothyroidism and obesity are two highly prevalent conditions that appear to be closely related. Hypothyroidism is correlated with weight gain, loss of appetite, constipation, and a higher incidence of obesity. The present study aimed to investigate the effects of synbiotic supplementation on anthropometric indices, appetite, and constipation in subjects with hypothyroidism. Sixty subjects with hypothyroidism were assigned into two groups to receive either 500 mg/day of synbiotic (n = 30) or a placebo (n = 30) per day for 8 weeks. Anthropometric indices, appetite, and constipation were assessed at study baseline and end of the trial. At the end of trial, waist-to-hip ratio was significantly decreased in the synbiotic group (p = .030), whereas there were no significant differences between groups. We did not observe any statistically significant change in appetite or other anthropometric indices (p > .05). Compared with the placebo synbiotic supplementation led to a significant reduction in constipation (p = .048). The results of the present trial indicated that synbiotic supplementation may have favorable results in constipation among subjects with hypothyroidism for 8 weeks. Further studies with larger sample size and longer duration are needed to confirm our findings.

Nonalcoholic Fatty Liver Disease: Modulating Gut Microbiota to Improve Severity?

Gut microbiota plays a role in the pathophysiology of metabolic diseases, which include nonalcoholic fatty liver diseases, through the gut-liver axis. To date, clinical guidelines recommend a weight loss goal of 7%-10% to improve features of nonalcoholic fatty liver diseases. Because this target is not easily achieved by all patients, alternative therapeutic options are currently being evaluated. This review focuses on therapeutics that aim to modulate the gut microbiota and the gut-liver axis. We discuss how probiotics, prebiotics, synbiotic, fecal microbiota transfer, polyphenols, specific diets, and exercise interventions have been found to modify gut microbiota signatures; improve nonalcoholic fatty liver disease outcomes; and detail, when available, the different mechanisms by which these beneficial outcomes might occur. Apart from probiotics that have already been tested in human randomized controlled trials, most of these potential therapeutics have been studied in animals. Their efficacy still warrants confirmation in humans using appropriate design.

Peri-transplant renal dysfunction in patients with non-alcoholic steatohepatitis undergoing liver transplantation

Non-alcoholic fatty liver disease (NAFLD) is currently the most common etiology of chronic liver disease (CLD) caused by an accumulation of fat in the liver and globally is the leading indication of liver transplantation. Emerging data has recognized an increased association of NAFLD with risk of other metabolic liver diseases like type 2 diabetes mellitus, chronic kidney disease (CKD) and cardiovascular diseases. Pathophysiologically, NAFLD patients have a state of low-grade systemic inflammation, insulin resistance and atherogenic dyslipidemia which causes renal dysfunction. Patients with NAFLD cirrhosis awaiting liver transplant (LT) face unique challenges and have a significantly higher requirement of simultaneous-liver-kidney transplant as compared to other etiologies. Further, NAFLD not only recurs but also occurs as a de novo manifestation post-LT. There is also a significantly higher risk of waiting list stagnation and dropouts due to burdensome cardiometabolic disorders in NAFLD patients. The current review aims to understand the prevalence and pathogenetic basis of renal dysfunction in NAFLD. Additionally, the review describes the choice of immunosuppression protocols and use of intraoperative renal replacement therapy in context of intra and post-operative renal dysfunction in NAFLD patients. Prospective controlled trials focusing on NAFLD and development of CKD are needed to assess the existence of a causal and/or a bidirectional relationship between NAFLD and CKD.

Bidirectional interactions between curcumin and gut microbiota in transgenic mice with Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disease with increasing prevalence worldwide, while there are no effective drugs at present. Curcumin, a natural polyphenolic substance isolated from turmeric, is a promising natural compound to combat AD, but its pharmacology remains to be fully understood for its poor in vivo bioavalibility. Inspired by the recently reported associations between gut microbiota and AD development, the present study investigated the interactions of curcumin with gut microbiota of APP/PS1 double transgenic mice from two directions: (i) curcumin influences gut microbiota, and (ii) gut microbiota biotransform curcumin. It was found that curcumin administration tended to improve the spatial learning and memory abilities and reduce the amyloid plaque burden in the hippocampus of APP/PS1 mice. On the one hand, curcumin administration altered significantly the relative abundances of bacterial taxa such as Bacteroidaceae, Prevotellaceae, Lactobacillaceae, and Rikenellaceae at family level, and Prevotella, Bacteroides, and Parabacteroides at genus level, several of which have been reported to be key bacterial species associated with AD development. On the other hand, a total of 8 metabolites of curcumin biotransformed by gut microbiota of AD mice through reduction, demethoxylation, demethylation and hydroxylation were identified by HPLC-Q-TOF/MS, and many of these metabolites have been reported to exhibit neuroprotective ability. The findings provided useful clues to understand the pharmacology of curcumin and microbiome-targeting therapies for AD.

Bile acid sequestration reverses liver injury and prevents progression of nonalcoholic steatohepatitis in Western diet-fed mice

Nonalcoholic fatty liver disease is a rapidly rising problem in the 21st century and is a leading cause of chronic liver disease that can lead to end-stage liver diseases, including cirrhosis and hepatocellular cancer. Despite this rising epidemic, no pharmacological treatment has yet been established to treat this disease. The rapidly increasing prevalence of nonalcoholic fatty liver disease and its aggressive form, nonalcoholic steatohepatitis (NASH), requires novel therapeutic approaches to prevent disease progression. Alterations in microbiome dynamics and dysbiosis play an important role in liver disease and may represent targetable pathways to treat liver disorders. Improving microbiome properties or restoring normal bile acid metabolism may prevent or slow the progression of liver diseases such as NASH. Importantly, aberrant systemic circulation of bile acids can greatly disrupt metabolic homeostasis. Bile acid sequestrants are orally administered polymers that bind bile acids in the intestine, forming nonabsorbable complexes. Bile acid sequestrants interrupt intestinal reabsorption of bile acids, decreasing their circulating levels. We determined that treatment with the bile acid sequestrant sevelamer reversed the liver injury and prevented the progression of NASH, including steatosis, inflammation, and fibrosis in a Western diet-induced NASH mouse model. Metabolomics and microbiome analysis revealed that this beneficial effect is associated with changes in the microbiota population and bile acid composition, including reversing microbiota complexity in cecum by increasing Lactobacillus and decreased Desulfovibrio The net effect of these changes was improvement in liver function and markers of liver injury and the positive effects of reversal of insulin resistance.

Mechanisms of Environmental Contributions to Fatty Liver Disease

PURPOSE

Fatty liver disease (FLD) affects over 25% of the global population and may lead to liver-related mortality due to cirrhosis and liver cancer. FLD caused by occupational and environmental chemical exposures is termed "toxicant-associated steatohepatitis" (TASH). The current review addresses the scientific progress made in the mechanistic understanding of TASH since its initial description in 2010.

RECENT FINDINGS

Recently discovered modes of actions for volatile organic compounds and persistent organic pollutants include the following: (i) the endocrine-, metabolism-, and signaling-disrupting chemical hypotheses; (ii) chemical-nutrient interactions and the "two-hit" hypothesis. These key hypotheses were then reviewed in the context of the steatosis adverse outcome pathway (AOP) proposed by the US Environmental Protection Agency. The conceptual understanding of the contribution of environmental exposures to FLD has progressed significantly. However, because this is a new research area, more studies including mechanistic human data are required to address current knowledge gaps.

Diet Consisting of Balanced Yogurt, Fruit, and Vegetables Modifies the Gut Microbiota and Protects Mice against Nonalcoholic Fatty Liver Disease

BACKGROUND

Calorie restriction (CR) is a therapeutically effective method for nonalcoholic fatty liver disease. However, the compliance of the CR method is relatively poor. New CR methods are needed.

METHODS AND RESULTS

Each week, mice are given a 5-day high-fat diet (HFD) ad libitum plus 2 days of an intermittent calorie restriction (ICR) diet (50% calorie restriction) consisting of yogurt, fruit, and vegetables, for 16 weeks. The effect of the ICR diet model on the fatty liver of mice is examined. Compared with continuous HFD-fed mice, the mice feeding HFD+ICR have lower body weight and hepatic steatosis, reduced serum lipid and transaminase levels, increased fatty acid oxidation gene of Cpt1a, and decreased hepatic lipid synthesis gene of Pparγ and Srebf-1c, as well as improved insulin resistance and lower level of inflammation. Moreover, ICR reverses the dysbacteriosis in HFD group, including the lower Shannon diversity indexes and lower abundance of Lactobacillus.

CONCLUSION

An ICR diet consisting of yogurt, fruit, and vegetables attenuates the development of HFD-induced hepatic steatosis in mice. Furthermore, HFD+ICR diet is associated with a different fecal microbiota that tends to be more similar to normal diet controls.

Role of the intestinal microbiome in liver fibrosis development and new treatment strategies

Liver cirrhosis is a major cause of morbidity and mortality worldwide. The most common chronic liver diseases in western countries are alcohol-associated liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD). Although these diseases have different causes, liver fibrosis develops via shared mechanisms. The liver and intestinal microbiome are linked by the portal vein and have bidirectional interactions. Changes in the intestinal microbiome contribute to the pathogenesis and progression of liver diseases including ALD, NAFLD, viral hepatitis and cholestatic disorders, based on studies in patients and animal models. Intestinal microbial dysbiosis has been associated with liver cirrhosis and its complications. We review the mechanisms by which alterations in the microbiome contribute to liver fibrosis and discuss microbiome-based treatment approaches.

Elevated oxysterol levels in human and mouse livers reflect nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH), a primary cause of liver disease, leads to complications such as fibrosis, cirrhosis, and carcinoma, but the pathophysiology of NASH is incompletely understood. Epstein-Barr virus-induced G protein-coupled receptor 2 (EBI2) and its oxysterol ligand 7α,25-dihydroxycholesterol (7α,25-diHC) are recently discovered immune regulators. Several lines of evidence suggest a role of oxysterols in NASH pathogenesis, but rigorous testing has not been performed. We measured oxysterol levels in the livers of NASH patients by LC-MS and tested the role of the EBI2-7α,25-diHC system in a murine feeding model of NASH. Free oxysterol profiling in livers from NASH patients revealed a pronounced increase in 24- and 7-hydroxylated oxysterols in NASH compared with controls. Levels of 24- and 7-hydroxylated oxysterols correlated with histological NASH activity. Histological analysis of murine liver samples demonstrated ballooning and liver inflammation. No significant genotype-related differences were observed in Ebi2^−/− mice and mice with defects in the 7α,25-diHC synthesizing enzymes CH25H and CYP7B1 compared with wild-type littermate controls, arguing against an essential role of these genes in NASH pathogenesis. Elevated 24- and 7-hydroxylated oxysterol levels were confirmed in murine NASH liver samples. Our results suggest increased bile acid synthesis in NASH samples, as judged by the enhanced level of 7α-hydroxycholest-4-en-3-one and impaired 24S-hydroxycholesterol metabolism as characteristic biochemical changes in livers affected by NASH.

Interaction of volatile organic compounds and underlying liver disease: a new paradigm for risk

Occupational and environmental exposures to industrial chemicals are known to cause hepatotoxicity and liver injury, in humans and in animal models. Historically, research has focused on severe acute liver injury (e.g. fulminant liver failure) or endstage diseases (e.g. cirrhosis and HCC). However, it has become recently recognized that toxicants can cause more subtle changes to the liver. For example, toxicant-associated steatohepatitis, characterized by hepatic steatosis, and inflammation, was recently recognized in an occupational cohort exposed to vinyl chloride. At high occupational levels, toxicants are sufficient to cause liver damage and disease even in healthy subjects with no comorbidities for liver injury. However, it is still largely unknown how exposure to toxicants initiate and possibly more importantly exacerbate liver disease, when combined with other factors, such as underlying non-alcoholic fatty liver disease caused by poor diet and/or obesity. With better understanding of the mechanism(s) and risk factors that mediate the initiation and progression of toxicant-induced liver disease, rational targeted therapy can be developed to better predict risk, as well as to treat or prevent this disease. The purpose of this review is to summarize established and proposed mechanisms of volatile organic compound-induced liver injury and to highlight key signaling events known or hypothesized to mediate these effects.

Phytosterols and Triterpenoids for Prevention and Treatment of Metabolic-related Liver Diseases and Hepatocellular Carcinoma

Background:

Liver ailments are among the leading causes of death; they originate from viral infections, chronic alcoholism, and autoimmune illnesses, which may chronically be precursors of cirrhosis; furthermore, metabolic syndrome may worsen those hepatopathies or cause Non-alcoholic Fatty Liver Disease (NAFLD) that may advance to non-alcoholic steatohepatitis (NASH). Cirrhosis is the late-stage liver disease and can proceed to hepatocellular carcinoma (HCC). Pharmacological treatment options for liver diseases, cirrhosis, and HCC, are limited, expensive, and not wholly effective. The use of medicinal herbs and functional foods is growing around the world as natural resources of bioactive compounds that would set the basis for the development of new drugs.

Review and Conclusion:

Plant and food-derived sterols and triterpenoids (TTP) possess antioxidant, metabolic-regulating, immunomodulatory, and anti-inflammatory activities, as well as they are recognized as anticancer agents, suggesting their application strongly as an alternative therapy in some chronic diseases. Thus, it is interesting to review current reports about them as hepatoprotective agents, but also because they structurally resemble cholesterol, sexual hormones, corticosteroids and bile acids due to the presence of the steroid nucleus, so they all can share pharmacological properties through activating nuclear and membrane receptors. Therefore, sterols and TTP appear as a feasible option for the prevention and treatment of chronic metabolic-related liver diseases, cirrhosis, and HCC.

Gut microbiota and its mysteries

Gut microbiota are microorganisms that inhabit the gut; they coexist peacefully with the host, thereby contributing to the health and well-being of individuals. Bacteroidetes and Firmicutes largely dominate the gut microbial flora. The intestinal flora promotes intestinal mucosal integrity, provides essential nutrients such as vitamins and enzymes, protects the body against pathogens and produces antimicrobial peptides such as defensins, C-type lectins, cathelicidins, they also play an active role in the innate and adaptive immune system. Gut microbial flora plays an active role in the synthesis of short-chain fatty acids such as butyrate, propionate and acetate. Gut microbiota also plays a significant role in the cognitive and behavioural functions of the host. A balanced gut microbiota shifts to dysbiosis, due to intake of high fat or sugar or other factors like sedentary lifestyle. The dysbiosis of the gut results in increased permeability, endotoxaemic, insulin resistant, systemic inflammation, adiposity and metabolic disorders such as type 2 diabetes mellitus, non-alcoholic fatty liver disease, non-alcoholic steatohepatitis, irritable bowel disorder, colorectal cancer, etc. A prudent lifestyle modification, added on with use of probiotics and prebiotic restore the normal flora of the gut, especially in patients with Clostridium difficle-associated diarrhoea, inflammatory bowel syndrome, liver disease and colon cancer. Faecal microbial transplant is an important therapeutic tool in many illness related with the gut. Thereby, understanding the gut microbial signatures in various diseases yields various novel therapeutic targets. Human gut microbiota has a prognostic, diagnostic and therapeutic potential which is recognised worldwide.

Intestinally derived bacterial products stimulate development of nonalcoholic steatohepatitis

Fatty livers are susceptible to factors that cause inflammation and fibrosis, but fat deposition and the inflammatory response can be dissociated. While nonalcoholic fatty liver disease (NAFLD), caused by pathologic fat accumulation inside the liver, can remain stable for several years, in other cases NAFLD progresses to nonalcoholic steatohepatitis (NASH), which is characterized by fat accumulation and inflammation and is not a benign condition. In this review, we discuss the NASH host cells and microbial mechanisms that stimulate inflammation and predispose the liver to hepatocyte injury and fibrotic stages via increased lipid deposition. We highlight the interactions between intestine-derived bacterial products, such as lipopolysaccharide, and nutritional models of NAFLD and/or obese individuals. The results of modulating enteric microbiota suggest that gut-derived endotoxins may be essential determinants of fibrotic progression and regression in NASH.

Hepatocellular Carcinoma Is Associated With Gut Microbiota Profile and Inflammation in Nonalcoholic Fatty Liver Disease

The gut-liver axis plays a pivotal role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD), which is the third leading cause of hepatocellular carcinoma (HCC) worldwide. However, the link between gut microbiota and hepatocarcinogenesis remains to be clarified. The aim of this study was to explore what features of the gut microbiota are associated with HCC in patients with cirrhosis and NAFLD. A consecutive series of patients with NAFLD-related cirrhosis and HCC (group 1, 21 patients), NAFLD-related cirrhosis without HCC (group 2, 20 patients), and healthy controls (group 3, 20 patients) was studied for gut microbiota profile, intestinal permeability, inflammatory status, and circulating mononuclear cells. We finally constructed a model depicting the most relevant correlations among these features, possibly involved in hepatocarcinogenesis. Patients with HCC showed increased levels of fecal calprotectin, while intestinal permeability was similar to patients with cirrhosis but without HCC. Plasma levels of interleukin 8 (IL8), IL13, chemokine (C-C motif) ligand (CCL) 3, CCL4, and CCL5 were higher in the HCC group and associated with an activated status of circulating monocytes. The fecal microbiota of the whole group of patients with cirrhosis showed higher abundance of Enterobacteriaceae and Streptococcus and a reduction in Akkermansia. Bacteroides and Ruminococcaceae were increased in the HCC group, while Bifidobacterium was reduced. Akkermansia and Bifidobacterium were inversely correlated with calprotectin concentration, which in turn was associated with humoral and cellular inflammatory markers. A similar behavior was also observed for Bacteroides. Conclusion: Our results suggest that in patients with cirrhosis and NAFLD the gut microbiota profile and systemic inflammation are significantly correlated and can concur in the process of hepatocarcinogenesis.

A changing paradigm: management and treatment of the HCV/HIV-co-infected patient

Hepatitis C virus (HCV) treatment in HIV/HCV co-infected individuals has renewed relevance given the ongoing opioid crisis and rise of new HIV and HCV infections associated with injection drug use. Patients co-infected with HIV and HCV demonstrate increased rates of hepatic fibrosis, progression to liver failure, and liver-related mortality. HIV co-infection does not impact outcomes of current HCV treatments, and patients should be treated the same as HCV mono-infected persons, though attention to drug:drug interactions is required. In this review, we discuss the mechanisms mediating injury to the liver in HIV mono-infection and HIV/HCV co-infection, and present the landmark trials of HCV treatment in HIV-infected individuals.

Mechanistic and therapeutic advances in non-alcoholic fatty liver disease by targeting the gut microbiota

Non-alcoholic fatty liver disease (NAFLD) is one of the most common metabolic diseases currently in the context of obesity worldwide, which contains a spectrum of chronic liver diseases, including hepatic steatosis, non-alcoholic steatohepatitis and hepatic carcinoma. In addition to the classical "Two-hit" theory, NAFLD has been recognized as a typical gut microbiota-related disease because of the intricate role of gut microbiota in maintaining human health and disease formation. Moreover, gut microbiota is even regarded as a "metabolic organ" that play complementary roles to that of liver in many aspects. The mechanisms underlying gut microbiota-mediated development of NAFLD include modulation of host energy metabolism, insulin sensitivity, and bile acid and choline metabolism. As a result, gut microbiota have been emerging as a novel therapeutic target for NAFLD by manipulating it in various ways, including probiotics, prebiotics, synbiotics, antibiotics, fecal microbiota transplantation, and herbal components. In this review, we summarized the most recent advances in gut microbiota-mediated mechanisms, as well as gut microbiota-targeted therapies on NAFLD.

Nonalcoholic Fatty Liver Disease in Children: Not a Small Matter

The prevalence of nonalcoholic fatty liver disease (NAFLD) has increased substantially in the past two decades and NAFLD has now become the most common cause of chronic liver disease in children and adolescents. NAFLD is a broad clinicopathologic spectrum ranging from simple steatosis to varying degrees of necroinflammation called nonalcoholic steatohepatitis (NASH), leading to fibrosis and subsequently to cirrhosis. Despite the increasing prevalence and progressive nature of NAFLD even among children, therapy for NAFLD in both adults and children are limited. Weight loss remains the only consistently effective therapy for NAFLD. Pharmacologic options are even more limited in children than in adults with NAFLD. Vitamin E has been shown to be effective in improving histology in children with NASH. Few pharmacologic options such as metformin, probiotics, omega-3 fatty acids, and cysteamine bitartrate have been studied in children, with limited beneficial effects. However, these studies are limited by small sample size and heterogeneity of outcome assessment after treatment. Recent studies show promising results with bariatric surgery with regards to weight loss and improvement in liver histology in adolescents with NAFLD. In this review article, we discuss epidemiology, pathophysiology, and extrahepatic comorbidities of pediatric NAFLD and review existing therapeutic options for children with NAFLD. We also review novel therapeutic strategies studied in adults that could potentially be studied in children in the future.

Volatile Oil of Amomum villosum Inhibits Nonalcoholic Fatty Liver Disease via the Gut-Liver Axis

Background

The dried mature fruit of Amomum villosum has been historically used in China as food and in the auxiliary treatment of digestive system disorders. Numerous studies have shown that gastrointestinal function is closely related to the development of nonalcoholic fatty liver disease via the “gut-liver” axis.

Objective

The present study aimed to explore whether the mechanism underlying the regulation of lipid accumulation in nonalcoholic fatty liver disease (NAFLD) may affect related disorders using the active ingredients in A. villosum.

Design

Male Sprague-Dawley rats on a high-fat diet (HFD) to induce NAFLD were administered water extract of A. villosum (WEAV), volatile oil of A. villosum (VOAV), or bornyl acetate. After treatment, serum and liver total cholesterol (TC), triglyceride (TG), free fatty acid (FFA), aspartate aminotransferase (AST), alanine aminotransferase (ALT), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) levels were measured. The regulatory role of A. villosum in the microecology of the intestines was assessed using the V4 region of the 16S rDNA sequencing. The expression of the intestinal tight junction proteins occludin and ZO-1 was also measured. The influence of A. villosum on TLR4-mediated chronic low-grade inflammation was evaluated based on the concentrations of key proteins of the TLR4/NF-кB signaling pathway. Results. A. villosum effectively inhibited endogenous lipid synthesis, reduced TG, TC, and FFA accumulation, regulated the expression of LDL-C, and decreased lipid accumulation in liver tissues. VOAV effectively regulated the intestinal microflora, improved chronic low-grade inflammation by promoting ZO-1 and occludin protein expressions, and inhibited the TLR4/NF-кB signaling pathway.

Conclusion

The present study provides scientific basis for the potential application of A. villosum in NAFLD prevention and treatment. Additional chemical constituents other than bornyl acetate also contributed to the preventive effects of A. villosum on NAFLD.

2,3,5,4'-tetrahydroxy-stilbene-2-O-β-D-glucoside attenuates methionine and choline-deficient diet-induced non-alcoholic fatty liver disease

Previous studies have suggested that 2,3,5,4′-tetrahydroxy-stilbene-2-O-β-D-glucoside (TSG) prevents progression of non-alcoholic fatty liver disease (NAFLD) induced by high-fat diet. The present study aimed to evaluate whether TSG could reverse NAFLD induced by a methionine and choline-deficient (MCD) diet and identify the possible mechanism of action. C57BL6/J mice were fed a MCD diet and were treated with TSG, fenofibrate, and resveratrol for 9 weeks. Regulatory effects of several cytokines and enzymes, including Nod-like receptor protein 3, apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain (ASC), caspase-1, interleukin (IL)-18, IL-1β, and gut microbiota balance were investigated. TSG significantly reduced NAFLD biochemical indexes, including total cholesterol, triglyceride, low density lipoprotein cholesterol, very low density lipoprotein cholesterol, aspartate aminotransferase and free fatty acid. Middle dosage (TSG.M, 35 mg/kg) of TSG reduced the expression of ASC and caspase-1. Furthermore, TSG displayed gut microbiota regulatory effects on MCD-induced NAFLD mice. The results of the present study suggested that TSG prevented the occurrence and development of MCD diet-induced NAFLD. The data further indicated that TSG may serve as a promising lead compound that may aid with intervention in NAFLD therapy.

The Role of the Gut Microbiome in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease, with prevalence increasing in parallel with the rising incidence in obesity. Believed to be a "multiple-hit" disease, several factors contribute to NAFLD initiation and progression. Of these, the gut microbiome is gaining interest as a significant factor in NAFLD prevalence. In this paper, we provide an in-depth review of the progression of NAFLD, discussing the mechanistic modes of hepatocyte injury and the potential role for manipulation of the gut microbiome as a therapeutic strategy in the prevention and treatment of NAFLD.

Underrated enemy - from nonalcoholic fatty liver disease to cancers of the gastrointestinal tract

Nonalcoholic fatty liver disease (NAFLD) is intrahepatic ectopic lipid deposition which is present despite a lack of other causes of secondary hepatic fat accumulation. It is the most common chronic liver disorder in the welldeveloped countries. NAFLD is a multidisciplinary disease that affects various systems and organs and is inextricably linked to simple obesity, metabolic syndrome, insulin resistance and overt diabetes mellitus type 2. The positive energy balance related to obesity leads to a variety of systemic changes including modified levels of insulin, insulin- like growth factor-1, adipokines, hepatokines and cytokines. It is strongly linked to carcinogenesis and new evidence proves that NAFLD is associated with higher risk of all-cause mortality and cancer-specific mortality among cancer survivors. This article focuses on the association between NAFLD and extrahepatic gastrointestinal tract cancers, aiming to shed light on the pathomechanism of changes leading to the development of tumors.

Interleukin-23 promotes intestinal T helper type17 immunity and ameliorates obesity-associated metabolic syndrome in a murine high-fat diet model

We addressed the role of interleukin-23 (IL-23) in driving the intestinal T helper type 17 (Th17) response during obesity and metabolic syndrome progression induced by a high-fat diet (HFD). Diet-induced obese and lean mice received HFD or control diet (CTD), respectively, for 20 weeks. The nutritional, metabolic and immune parameters were examined at weeks 9 and 20. Gene and protein IL-23p19 and IL-23 receptor expression was increased in the ileum of obese wild-type mice (WT) fed the HFD for 9 weeks. Mice lacking IL-23 and fed the HFD exhibited greater weight gain, higher fat accumulation, adipocyte hypertrophy and hepatic steatosis. Notably, these mice had more glucose intolerance, insulin resistance and associated metabolic alterations, such as hyperinsulinaemia and hyperlipidaemia. IL-23 deficiency also significantly reduced protein levels of IL-17, CCL20 and neutrophil elastase in the ileum and reduced Th17 cell expansion in the mesenteric lymph nodes of the HFD mice. Of importance, IL-23-deficient mice exhibited increased gut permeability and blood bacterial translocation compared with WT mice fed HFD. Finally, metagenomics analysis of gut microbiota revealed a dramatic outgrowth of Bacteroidetes over Firmicutes phylum with the prevalence of Bacteroides genera in the faeces of IL-23-deficient mice after HFD. In summary, IL-23 appears to maintain the Th17 response and neutrophil migration into the intestinal mucosa, minimizing the gut dysbiosis and protecting against obesity and metabolic disease development in mice.

Nicotinamide adenine dinucleotide phosphate (reduced) oxidase 2 modulates inflammatory vigor during nonalcoholic fatty liver disease progression in mice

Nonalcoholic fatty liver disease (NAFLD) represents a disease spectrum ranging from benign steatosis to life-threatening cirrhosis and hepatocellular carcinoma. Elevated levels of reactive oxygen species (ROS) and exacerbated inflammatory responses have been implicated in NAFLD progression. Nicotinamide adenine dinucleotide phosphate (reduced) oxidase 2 (NOX2; also known as gp91Phox), the main catalytic subunit of the nicotinamide adenine dinucleotide phosphate (reduced) oxidase complex, modulates ROS production, immune responsiveness, and pathogenesis of obesity-associated metabolic derangements. However, the role of NOX2 in the regulation of immune cell function and inflammatory vigor in NAFLD remains underdefined. Here, we demonstrate that obesogenic diet feeding promoted ROS production by bone marrow, white adipose tissue, and liver immune cells. Genetic ablation of NOX2 impeded immune cell ROS synthesis and was sufficient to uncouple obesity from glucose dysmetabolism and NAFLD pathogenesis. Protection from hepatocellular damage in NOX2-deficient mice correlated with reduced hepatic neutrophil, macrophage, and T-cell infiltration, diminished production of key NAFLD-driving proinflammatory cytokines, and an inherent reduction in T-cell polarization toward Th17 phenotype. Conclusion: Current findings demonstrate a crucial role of the NOX2-ROS axis in immune cell effector function and polarization and consequent NAFLD progression in obesity. Pharmacologic targeting of NOX2 function in immune cells may represent a viable approach for reducing morbidity of obesity-associated NAFLD pathogenesis. (Hepatology Communications 2018;2:546-560).

Peroxisomal β-oxidation regulates whole body metabolism, inflammatory vigor, and pathogenesis of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD), a metabolic predisposition for development of hepatocellular carcinoma (HCC), represents a disease spectrum ranging from steatosis to steatohepatitis to cirrhosis. Acox1, a rate-limiting enzyme in peroxisomal fatty acid β-oxidation, regulates metabolism, spontaneous hepatic steatosis, and hepatocellular damage over time. However, it is unknown whether Acox1 modulates inflammation relevant to NAFLD pathogenesis or if Acox1-associated metabolic and inflammatory derangements uncover and accelerate potential for NAFLD progression. Here, we show that mice with a point mutation in Acox1 (Acox1Lampe1) exhibited altered cellular metabolism, modified T cell polarization, and exacerbated immune cell inflammatory potential. Further, in context of a brief obesogenic diet stress, NAFLD progression associated with Acox1 mutation resulted in significantly accelerated and exacerbated hepatocellular damage via induction of profound histological changes in hepatocytes, hepatic inflammation, and robust upregulation of gene expression associated with HCC development. Collectively, these data demonstrate that β-oxidation links metabolism and immune responsiveness and that a better understanding of peroxisomal β-oxidation may allow for discovery of mechanisms central for NAFLD progression.

Analogy between non-alcoholic steatohepatitis (NASH) and hypertension: a stepwise patient-tailored approach for NASH treatment

Non-alcoholic steatohepatitis (NASH) is a common liver disorder worldwide. Although there has been improvement in our understanding of the natural history and pathogenesis of the disease, there is still no approved therapy for NASH. NASH shares many similarities with primary hypertension, in that both are extremely common disorders that can easily lead to serious complications if left untreated. Both conditions are viewed as "silent killers", because the disease can progress over a period of time prior to the occurrence of potentially deadly outcomes. While attempts to find the "miracle pill" for NASH are unrealistic, we can make an analogy with the "stepwise combination" approach developed over the last few decades for the treatment of hypertension. In the present review, we summarize some of the similarities in the concepts that underlie NASH and hypertension. The development of a stepwise patient-tailored method for the treatment of NASH is presented.

Digoxin Suppresses Pyruvate Kinase M2-Promoted HIF-1α Transactivation in Steatohepatitis

Sterile inflammation after tissue damage is a ubiquitous response, yet it has the highest amplitude in the liver. This has major clinical consequences, for alcoholic and non-alcoholic steatohepatitis (ASH and NASH) account for the majority of liver disease in industrialized countries and both lack therapy. Requirements for sustained sterile inflammation include increased oxidative stress and activation of the HIF-1α signaling pathway. We demonstrate the ability of digoxin, a cardiac glycoside, to protect from liver inflammation and damage in ASH and NASH. Digoxin was effective in maintaining cellular redox homeostasis and suppressing HIF-1α pathway activation. A proteomic screen revealed that digoxin binds pyruvate kinase M2 (PKM2), and independently of PKM2 kinase activity results in chromatin remodeling and downregulation of HIF-1α transactivation. These data identify PKM2 as a mediator and therapeutic target for regulating liver sterile inflammation, and demonstrate a novel role for digoxin that can effectively protect the liver from ASH and NASH.

Nonalcoholic fatty liver disease and chronic vascular complications of diabetes mellitus

Nonalcoholic fatty liver disease (NAFLD) and diabetes mellitus are common diseases that often coexist and might act synergistically to increase the risk of hepatic and extra-hepatic clinical outcomes. NAFLD affects up to 70-80% of patients with type 2 diabetes mellitus and up to 30-40% of adults with type 1 diabetes mellitus. The coexistence of NAFLD and diabetes mellitus increases the risk of developing not only the more severe forms of NAFLD but also chronic vascular complications of diabetes mellitus. Indeed, substantial evidence links NAFLD with an increased risk of developing cardiovascular disease and other cardiac and arrhythmic complications in patients with type 1 diabetes mellitus or type 2 diabetes mellitus. NAFLD is also associated with an increased risk of developing microvascular diabetic complications, especially chronic kidney disease. This Review focuses on the strong association between NAFLD and the risk of chronic vascular complications in patients with type 1 diabetes mellitus or type 2 diabetes mellitus, thereby promoting an increased awareness of the extra-hepatic implications of this increasingly prevalent and burdensome liver disease. We also discuss the putative underlying mechanisms by which NAFLD contributes to vascular diseases, as well as the emerging role of changes in the gut microbiota (dysbiosis) in the pathogenesis of NAFLD and associated vascular diseases.