Current Research on the Pathogenesis of NAFLD/NASH and the Gut–Liver Axis: Gut Microbiota, Dysbiosis, and Leaky-Gut Syndrome

Global lifestyle changes have led to an increased incidence of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH), requiring further in-depth research to understand the mechanisms and develop new therapeutic strategies. In particular, high-fat and high-fructose diets have been shown to increase intestinal permeability, which can expose the liver to endotoxins. Indeed, accumulating evidence points to a link between these liver diseases and the intestinal axis, including dysbiosis of the gut microbiome and leaky-gut syndrome. Here, we review the mechanisms contributing to these links between the liver and small intestine in the pathogenesis of NAFLD/NASH, focusing on the roles of intestinal microbiota and their metabolites to influence enzymes essential for proper liver metabolism and function. Advances in next-generation sequencing technology have facilitated analyses of the metagenome, providing new insights into the roles of the intestinal microbiota and their functions in physiological and pathological mechanisms. This review summarizes recent research linking the gut microbiome to liver diseases, offering new research directions to elucidate the detailed mechanisms and novel targets for treatment and prevention

Frontiers of Collaboration between Primary Care and Specialists in the Management of Metabolic Dysfunction-Associated Steatotic Liver Disease: A Review

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease (NAFLD), is the most common liver disease. It has a rapidly growing patient population owing to the increasing prevalence of obesity and type 2 diabetes. Patients with MASLD are primarily treated by family physicians when fibrosis is absent or mild and by gastroenterologists/hepatologists when fibrosis is more advanced. It is imperative that a system for the appropriate treatment and surveillance of hepatocellular carcinoma be established in order to ensure that highly fibrotic cases are not overlooked among the large number of MASLD patients. Family physicians should check for viral hepatitis, autoimmune hepatitis, alcoholic liver disease, and drug-induced liver disease, and should evaluate fibrosis using NIT; gastroenterologists/hepatologists should perform liver biopsy, ultrasound elastography (260 units in Japan as of October 2023), and MR elastography (35 units in Japan as of October 2023). This review presents the latest findings in MASLD and the role, accuracy, and clinical use of NIT. It also describes the collaboration between Japanese primary care and gastroenterologists/hepatologists in Japan in the treatment of liver diseases, including MASLD

Non-invasive imaging biomarkers for liver steatosis in non-alcoholic fatty liver disease: present and future

Non-alcoholic fatty liver disease is currently the most common chronic liver disease, affecting up to 25% of the global population. Simple fatty liver, in which fat is deposited in the liver without fibrosis, has been regarded as a benign disease in the past, but it is now known to be prognostic. In the future, more emphasis should be placed on the quantification of liver fat. Traditionally, fatty liver has been assessed by histological evaluation, which requires an invasive examination; however, technological innovations have made it possible to evaluate fatty liver by non-invasive imaging methods, such as ultrasonography, computed tomography, and magnetic resonance imaging. In addition, quantitative as well as qualitative measurements for the detection of fatty liver have become available. In this review, we summarize the currently used qualitative evaluations of fatty liver and discuss quantitative evaluations that are expected to further develop in the future

Schizosaccharomyces pombe Sst4p, a Conserved Vps27/Hrs Homolog, Functions Downstream of Phosphatidylinositol 3-Kinase Pik3p To Mediate Proper Spore Formation▿ †

Sporulation of the fission yeast Schizosaccharomyces pombe is a developmental process that generates gametes and that includes the formation of spore envelope precursors called the forespore membranes. Assembly and development of forespore membranes require vesicular trafficking from other intracellular membrane compartments. We have shown that phosphatidylinositol 3-kinase (PtdIns 3-kinase) is required for efficient and proper development of forespore membranes. The role of a FYVE domain protein, Sst4p, a homolog of Vps27p/Hrs, as a downstream factor for PtdIns 3-kinase in sporulation was investigated. sst4Δ asci formed spores with oval-shaped morphology and with reduced viability compared to that of the wild-type spores. The extension of forespore membranes was inefficient, and bubble-like structures emerged from the leading edges of the forespore membranes. Sst4p localization was examined using fluorescent protein fusions and was found to be adjacent to the forespore membranes during sporulation. The localization and function of Sst4p were dependent on its FYVE domain and on PtdIns 3-kinase. Sst4p colocalized and interacted with Hse1p, a homolog of Saccharomyces cerevisiae Hse1p and of mammalian STAM. Mutations in all three UIM domains of the Sst4p/Hse1p complex resulted in formation of spores with abnormal morphology. These results suggest that Sst4p is a downstream factor of PtdIns 3-kinase and functions in forespore membrane formation

Chronological Course and Clinical Features after Denver Peritoneovenous Shunt Placement in Decompensated Liver Cirrhosis

Background: Refractory ascites affects the prognosis and quality of life in patients with liver cirrhosis. Peritoneovenous shunt (PVS) is a treatment procedure of palliative interventional radiology for refractory ascites. Although it is reportedly associated with serious complications (e.g., heart failure, thrombotic disease), the clinical course of PVS has not been thoroughly evaluated. Objectives: To evaluate the relationship between chronological course and complications after PVS for refractory ascites in liver cirrhosis patients. Materials and Methods: This was a retrospective study of 14 patients with refractory ascites associated with decompensated cirrhosis who underwent PVS placement between June 2011 and June 2023. The clinical characteristics, changes in cardiothoracic ratio (CTR), and laboratory data (i.e., brain natriuretic peptide (BNP), D-dimer, platelet) were evaluated. Follow-up CT images in eight patients were also evaluated for ascites and complications. Results: No serious complication associated with the procedure occurred in any case. Transient increases in BNP and D-dimer levels, decreased platelet counts, and the worsening of CTR were observed in the 2 days after PVS; however, they were improved in 7 days in all cases except one. In the follow-up CT, the amount of ascites decreased in all patients, but one patient with a continuous increase in D-dimer 2 and 7 days after PVS had thrombotic disease (renal and splenic infarction). The mean PVS patency was 345.4 days, and the median survival after PVS placement was 474.4 days. Conclusions: PVS placement for refractory ascites is a technically feasible palliative therapy. The combined evaluation of chronological changes in BNP, D-dimer, platelet count and CTR, and follow-up CT images may be useful for the early prediction of the efficacy and complications of PVS

Coronary Artery Disease is More Severe in Patients with Non-Alcoholic Steatohepatitis than Fatty Liver

Non-alcoholic fatty liver disease (NAFLD) is associated with a higher risk of atherosclerotic disease. However, the relationships between the severity of coronary atherosclerosis and pathologic findings in patients with NAFLD remain unknown. We aimed to characterize the coronary artery lesions in patients with NAFLD using coronary computed tomography angiography (CCTA). Overall, 101 patients with liver biopsy-proven NAFLD who had chest pain or electrocardiographic abnormalities underwent CCTA. Coronary artery lesions, including coronary artery stenosis (CAS), calcium score (CACS, Agatston score), and coronary artery non-calcified plaque were assessed using multi-slice CT. Multivariate analysis showed that age, smoking status, prevalence of dyslipidemia (DLP) and non-alcoholic steatohepatitis (NASH), and stage of fibrosis were independent risk factors for CAS. Age, and the prevalence of DM and DLP, were independent risk factors for CACS, and the prevalence of NASH tended to be an independent risk factor. In addition, the prevalence of DLP and NASH were independent risk factors for non-calcified plaques. Coronary artery lesions are more common in patients with NASH than in those with non-alcoholic fatty liver, suggesting a higher risk in patients with NASH. Therefore, patients with NASH should be closely followed, with particular vigilance for coronary artery diseases

Protective effect of SGL5213, a potent intestinal sodium-glucose cotransporter 1 inhibitor, in nonalcoholic fatty liver disease in mice.

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic disease. SGL5213, which is minimally absorbed and is restricted to the intestinal tract, is a potent intestinal sodium-glucose cotransporter 1 (SGLT1) inhibitor. In this study, we investigated the protective effect of SGL5213 in a rodent model of NAFLD.Using a rodent model of NAFLD, we compared SGL5213 efficacy with miglitol, which is an α-glucosidase inhibitor. We used a high-fat and high-sucrose diet-induced NAFLD model.SGL5213 and miglitol improved obesity, liver dysfunction, insulin resistance, and the NAFLD severity. To further investigate the effects of SGL5213, we analyzed the mRNA expression of genes involved in lipid metabolism, inflammation, and liver fibrosis, and cecal pH levels. SGL5213 and miglitol treatment significantly decreased mRNA expression of factors involved in inflammation and liver fibrosis. SGL5213 treatment significantly decreased cecal pH levels, which did not occur with miglitol.SGL5213 had a protective effect on the pathogenesis of NAFLD in a rodent model. We considered that inhibiting glucose absorption and increasing glucose content in the gastrointestinal tract with SGL5213 might have contributed to the protective effect in NAFLD. SGL5213 is a promising therapeutic agent for NAFLD with obesity and insulin resistance.Nonalcoholic fatty liver disease (NAFLD) is the most common chronic disease. SGL5213, which is minimally absorbed and is restricted to the intestinal tract, is a potent intestinal sodium-glucose cotransporter 1 (SGLT1) inhibitor. In this study, we investigated the protective effect of SGL5213 in a rodent model of NAFLD.Using a rodent model of NAFLD, we compared SGL5213 efficacy with miglitol, which is an α-glucosidase inhibitor. We used a high-fat and high-sucrose diet-induced NAFLD model.SGL5213 and miglitol improved obesity, liver dysfunction, insulin resistance, and the NAFLD severity. To further investigate the effects of SGL5213, we analyzed the mRNA expression of genes involved in lipid metabolism, inflammation, and liver fibrosis, and cecal pH levels. SGL5213 and miglitol treatment significantly decreased mRNA expression of factors involved in inflammation and liver fibrosis. SGL5213 treatment significantly decreased cecal pH levels, which did not occur with miglitol.SGL5213 had a protective effect on the pathogenesis of NAFLD in a rodent model. We considered that inhibiting glucose absorption and increasing glucose content in the gastrointestinal tract with SGL5213 might have contributed to the protective effect in NAFLD. SGL5213 is a promising therapeutic agent for NAFLD with obesity and insulin resistance

Efficacy and safety of guanabenz acetate treatment for non-alcoholic fatty liver disease: a study protocol for a randomised investigator-initiated phase IIa study

Introduction Non-alcoholic fatty liver disease (NAFLD) is a metabolic syndrome phenotype in the liver and thus obviously associated with metabolic abnormalities, including insulin resistance-related to hyperglycaemic and hyperlipidaemia. The prevalence of NAFLD is increasing worldwide. However, currently, there is no consensus regarding the efficacy and safety of drugs used to treat patients with NAFLD/non-alcoholic steatohepatitis (NASH). Guanabenz acetate, a selective α2-adrenoceptor stimulator used in the treatment of hypertension, binds at a high-affinity constant to a nuclear transcriptional coregulator, helicase with zinc finger 2 (Helz2) and inhibits Helz2-medaited steatosis in the liver; chronic oral administration of guanabenz acetate produces a dose-dependent inhibition of lipid accumulation by inhibiting lipogenesis and activating fatty acid Β-oxidation in the liver of obese mice, resulting in improvement of insulin resistance and hyperlipidaemia. Taken all together, guanabenz acetate has a potentially effective in improving the development of NAFLD/NASH and metabolic abnormalities. In this randomised, open label, parallel-group, phase IIa study, we made attempts to conduct a proof-of-concept assessment by evaluating the efficacy and safety of guanabenz acetate treatment in patients with NAFLD/NASH.Methods and analysis A total of 28 adult patients with NAFLD or NASH and hypertension complications meeting the inclusion/exclusion criteria will be enrolled. Patients will be randomised to receive either 4 or 8 mg guanabenz acetate (n=14 per group). Blood tests and MRI will be performed 16 weeks after commencement of treatment. The primary endpoint will be the percentage reduction in hepatic fat content (%) measured using MRI-proton density fat fraction from baseline by at least 3.46% at week 16 after treatment initiation.Ethics and dissemination Ethics approval was obtained from the Ethics Committee of Yokohama City University Hospital before participant enrolment (YCU021001). The results of this study will be submitted for publication in international peer-reviewed journals, and the key findings will be presented at international scientific conferences. Participants wishing to know the results of this study will be contacted directly on data publication.Trial registration number This trial is registered with ClinicalTrials.gov (number: NCT05084404).Protocol version V.1.1, 19 August 2021

The Role of Leaky Gut in Nonalcoholic Fatty Liver Disease: A Novel Therapeutic Target

The liver directly accepts blood from the gut and is, therefore, exposed to intestinal bacteria. Recent studies have demonstrated a relationship between gut bacteria and nonalcoholic fatty liver disease (NAFLD). Approximately 10–20% of NAFLD patients develop nonalcoholic steatohepatitis (NASH), and endotoxins produced by Gram-negative bacilli may be involved in NAFLD pathogenesis. NAFLD hyperendotoxicemia has intestinal and hepatic factors. The intestinal factors include impaired intestinal barrier function (leaky gut syndrome) and dysbiosis due to increased abundance of ethanol-producing bacteria, which can change endogenous alcohol concentrations. The hepatic factors include hyperleptinemia, which is associated with an excessive response to endotoxins, leading to intrahepatic inflammation and fibrosis. Clinically, the relationship between gut bacteria and NAFLD has been targeted in some randomized controlled trials of probiotics and other agents, but the results have been inconsistent. A recent randomized, placebo-controlled study explored the utility of lubiprostone, a treatment for constipation, in restoring intestinal barrier function and improving the outcomes of NAFLD patients, marking a new phase in the development of novel therapies targeting the intestinal barrier. This review summarizes recent data from studies in animal models and randomized clinical trials on the role of the gut–liver axis in NAFLD pathogenesis and progression