Endotoxins and Non-Alcoholic Fatty Liver Disease

New advances in novel pharmacotherapeutic candidates for the treatment of metabolic dysfunction-associated steatohepatitis (MASH) between 2022 and 2024

Metabolic dysfunction-associated steatotic liver disease (MASLD) covers a broad spectrum of profile from simple fatty liver, evolving to metabolic dysfunction-associated steatohepatitis (MASH), to hepatic fibrosis, further progressing to cirrhosis and hepatocellular carcinoma (HCC). MASLD has become a prevalent disease with 25% in average over the world. MASH is an active stage, and requires pharmacological intervention when there is necroptotic damage with fibrotic progression. Although there is an increased understanding of MASH pathogenesis and newly approved resmetirom, given its complexity and heterogeneous pathophysiology, there is a strong necessity to develop more drug candidates with better therapeutic efficacy and well-tolerated safety profile. With an increased list of pharmaceutical candidates in the pipeline, it is anticipated to witness successful approval of more potential candidates in this fast-evolving field, thereby offering different categories of medications for selective patient populations. In this review, we update the advances in MASH pharmacotherapeutics that have completed phase II or III clinical trials with potential application in clinical practice during the latest 2 years, focusing on effectiveness and safety issues. The overview of fast-evolving status of pharmacotherapeutic candidates for MASH treatment confers deep insights into the key issues, such as molecular targets, endpoint selection and validation, clinical trial design and execution, interaction with drug administration authority, real-world data feedback and further adjustment in clinical application.

Dual-Targeted Nanoparticles Hitchhiking on Lactobacillus rhamnosus Bacterial Ghosts to Alleviate Nonalcoholic Steatohepatitis

Oral nutritional interventions for nonalcoholic steatohepatitis (NASH) have garnered significant interest due to their potential benefits. Astaxanthin (AXT) has the potential to enhance liver function and act as an effective antioxidant for NASH intervention, but its application is limited by its stability and bioavailability. This study aims to develop dual-targeted AXT nanoparticles (AXT@TWG) for precise liver-targeted delivery by ″hitchhiking″ on Lactobacillus rhamnosus bacterial ghosts (LBGs) to effectively intervene in NASH. In vitro experiments demonstrated that AXT@TWG nanoparticles significantly reduced LPS-induced reactive oxygen species production and apoptosis while effectively alleviating lipid accumulation. In vivo experiments demonstrated that LBGs significantly enhanced the intestinal accumulation efficiency of AXT@TWG. Pharmacokinetic evaluations revealed that the efficiency of AXT@TWG@LBGs entering the bloodstream was approximately 2.7 times higher than that of AXT@TWG nanoparticles and their accumulation in the liver was about 1.3 times greater. AXT@TWG@LBGs effectively alleviated NASH by reducing triglycerides, free fatty acids, and malondialdehyde levels by 23.07, 65.32, and 21.42%, respectively, compared to the model group, thereby mitigating lipid accumulation and enhancing antioxidant capacity. Additionally, AXT@TWG@LBGs effectively reduced insulin resistance, lowered inflammatory cytokine levels, and corrected disturbances in lipid metabolism. Therefore, this study provides a potentially effective strategy for the treatment of NASH.

Therapeutic Role of Probiotics Against Environmental-Induced Hepatotoxicity: Mechanisms, Clinical Perspectives, Limitations, and Future

Hepatotoxicity is one of the biggest health challenges, particularly in the context of liver diseases, often aggravated by gut microbiota dysbiosis. The gut-liver axis has been regarded as a key idea in liver health. It indicates that changes in gut flora caused by various hepatotoxicants, including alcoholism, acetaminophen, carbon tetrachloride, and thioacetamide, can affect the balance of the gut's microflora, which may lead to increased dysbiosis and intestinal permeability. As a result, bacterial endotoxins would eventually enter the bloodstream and liver, causing hepatotoxicity and inducing inflammatory reactions. Many treatments, including liver transplantation and modern drugs, can be used to address these issues. However, because of the many side effects of these approaches, scientists and medical experts are still hoping for a therapeutic approach with fewer side effects and more positive results. Thus, probiotics have become well-known as an adjunctive strategy for managing, preventing, or reducing hepatotoxicity in treating liver injury. By altering the gut microbiota, probiotics offer a secure, non-invasive, and economical way to improve liver health in the treatment of hepatotoxicity. Through various mechanisms such as regulation of gut microbiota, reduction of pathogenic overgrowth, suppression of inflammatory mediators, modification of hepatic lipid metabolism, improvement in the performance of the epithelial barrier of the gut, antioxidative effects, and modulation of mucosal immunity, probiotics play their role in the treatment and prevention of hepatotoxicity. This review highlights the mechanistic effects of probiotics in environmental toxicants-induced hepatotoxicity and current findings on this therapeutic approach's experimental and clinical trials.

Role of serum endotoxin, FGF19, TLR2, TNF-α, IL-12 and IL-10 in NAFLD-associated T2DM pathogenesis: Insights into Th1 bias and protective mechanisms

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) in non-obese patients is pathophysiologically distinct, exhibiting common immunological link with type-2 diabetes mellitus (T2DM). This study aims to delineate the role of Toll-like receptor 2 (TLR2)-mediated immuno-modulation along with its association with fibroblast growth factor receptor 4 (FGFR4) and its ligand fibroblast growth factor 19 (FGF19) in the pathogenesis of NAFLD without or with T2DM.

METHODOLOGY

Blood samples were collected from patients with NAFLD (n = 90), NAFLD with T2DM (n = 90) and healthy cohorts (n = 90) with consent and clinical records. Real-time polymerase chain reaction (PCR), enzyme-linked immunoassay (ELIZA) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) were used to analyze messenger ribonucleic acid (mRNA), protein expression and gene polymorphism.

RESULTS

The molecular genetic analysis revealed the prevalence of variant allele(A) in FGFR4 gene in both cases compared to controls. The mRNA expression of FGF19 and TLR2 exhibited significant upregulation in NAFLD without T2DM compared to NAFLD with T2DM. Tumor necrosis factor-α (TNF-α) and interleukin-12 (IL-12) showed upregulation in both disease cohorts compared to control while IL-10 showed significant downregulation in NAFLD with T2DM compared to the other two cohorts. Correlation analysis between FGF19 and TLR2 revealed significant positive association in both NAFLD with and without T2DM. The Th1:Th2 ratio showed significant upregulation in NAFLD with T2DM compared to NAFLD without T2DM.

CONCLUSION

In conclusion, elevated serum endotoxin levels appear to contribute to NAFLD and T2DM development. Upregulated FGF19 seems to be protective against developing T2DM in NAFLD patients. Higher TLR2, TNF-α and IL-12 expression in NAFLD without T2DM suggests a Th1 bias in its pathogenesis, while reduced IL-10 in NAFLD with T2DM implies a more skewed Th1 state in this condition.

Differential modulation of the hepatocellular metabolome, cytoprotective and inflammatory responses due to endotoxemia and lipotoxicity

The present work aimed to examine the primary mechanisms of liver damage, namely the impact of gut-derived endotoxins along the gut-liver axis and adipose-derived free fatty acids along the adipose-liver axis. These processes are known to play a significant role in the development of hepatic inflammation and steatosis. Although possible overlapping in the pathogenesis was expected, these processes have unique pathophysiological consequences. Therefore, we used HepG2 cells as a model system to investigate the impact of lipopolysaccharides (LPS) and free fatty acid (FFA; albumin conjugated palmitic acid) on the intracellular metabolome. Although both LPS and FFA triggered the expression of nuclear factor κB (NFκB)-dependent inflammation, only LPS treatment was able to trigger a Toll-like receptor 4 (TLR4) dependent response. The intracellular cytoprotective enzymatic levels (catalase, peroxidase, glutathione) were increased due to FFA but lowered due to LPS. The free-radical neutralizing efficacies of cell-free metabolites of FFA-treated cells were better than those of the LPS-treated ones. The use of untargeted metabolomics allowed for the identification of distinct metabolic pathway enrichments, providing further insights into the differential effects of LPS and FFA on the metabolism of hepatocytes. Collectively, the current study highlights the distinct impacts of endotoxemia and lipotoxicity on the metabolome of hepatocytes, hence offering valuable insights into hepatocellular function.

Mechanistic Insights into the Role of MCP-1 in Diverse Liver Pathological Conditions: A Recent Update

Monocyte chemoattractant protein-1 (MCP-1) is regarded as a crucial proinflammatory cytokine that controls the migration and entry of macrophages. It has been demonstrated that chemokine ligand 2 and its receptor, chemokine receptor 2, are both implicated in several liver disorders. In a similar context, immunity mediators are overexpressed and stimulated by MCP-1. Additionally, MCP-1 alters the physiology of the hepatocytes, promoting immunologic and inflammatory responses beyond regular metabolism. Alcoholism and other factor including abnormal diet stimulate the liver's synthesis of MCP-1, which can result in inflammation in liver. Studies shows how MCP-1' linked to various liver disorders like alcoholic liver disease, liver fibrosis, non-alcoholic fatty liver disease, hepatitis, hepatic steatosis, hepatocellular cancer, primary biliary cirrhosis. MCP-1 not only predicts the onset, progression, and prognosis of the illness, but it is also directly related to the degree and stage of liver inflammation. In this review, we will explore the mechanism and connection between MCP-1's overexpression in liver disorders, further how it can be linked as a therapeutic biomarker in the above scenario.

Post-COVID metabolic enzyme alterations in K18-hACE2 mice exacerbate alcohol-induced liver injury through transcriptional regulation

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), poses a significant threat to global public health. Despite reports of liver injury during viral disease, the occurrence and detailed mechanisms underlying the development of secondary exogenous liver injury, particularly in relation to changes in metabolic enzymes, remain to be fully elucidated. Therefore, this study was aimed to investigate the mechanisms underlying SARS-CoV-2-induced molecular alterations in hepatic metabolism and the consequent secondary liver injury resulting from alcohol exposure. We investigated the potential effects of SARS-CoV-2 infection on alcohol-induced liver injury in Keratin 18 promoter-human angiotensin converting enzyme 2 (K18-hACE2) transgenic mice. Mice were intranasally infected with 1 × 102 PFU of SARS-CoV-2. Following a 14 d recovery period from infection, the recovered mice were orally administered alcohol at 6 g/kg. Prior SARS-CoV-2 infection aggravated alcohol-induced liver injury based on increased alanine aminotransferase levels and cytoplasmic vacuolation. Interestingly, infected mice exhibited lower blood alcohol levels and higher levels of acetaldehyde, a toxic alcohol metabolite, compared to uninfected mice after the same period of alcohol consumption. Along with alterations of several metabolic process-related terms identified through RNA sequencing, notably, upregulation of cytochrome P450 2E1 (CYP2E1) and CYP1A2 was observed in infected mice compared to control value prior to alcohol exposure, with no significant impact of SARS-CoV-2 on intestinal damage. Tumor necrosis factor-alpha persistently showed upregulated expression in the infected mice; it also enhanced aryl hydrocarbon receptor and Sp1 expressions and their binding activity to Cyp1a2 and Cyp2e1 promoters, respectively, in hepatocytes, promoting the upregulation of their transcription. Our findings suggest that SARS-CoV-2 infection exacerbates alcohol-induced liver injury through the transcriptional activation of Cyp1a2 and Cyp2e1, providing valuable insights for the development of clinical recommendations on long COVID.

Current Therapeutic Landscape for Metabolic Dysfunction-Associated Steatohepatitis

In recent years, "metabolic dysfunction-associated steatotic liver disease" (MASLD) has been proposed to better connect liver disease to metabolic dysfunction, which is the most common chronic liver disease worldwide. MASLD affects more than 30% of individuals globally, and it is diagnosed by the combination of hepatic steatosis and obesity, type 2 diabetes, or two metabolic risk factors. MASLD begins with the buildup of extra fat, often greater than 5%, within the liver, causing liver hepatocytes to become stressed. This can proceed to a more severe form, metabolic dysfunction-associated steatohepatitis (MASH), in 20-30% of people, where inflammation in the liver causes tissue fibrosis, which limits blood flow over time. As fibrosis worsens, MASH may lead to cirrhosis, liver failure, or even liver cancer. While the pathophysiology of MASLD is not fully known, the current "multiple-hits" concept proposes that dietary and lifestyle factors, metabolic factors, and genetic or epigenetic factors contribute to elevated oxidative stress and inflammation, causing liver fibrosis. This review article provides an overview of the pathogenesis of MASLD and evaluates existing therapies as well as pharmacological drugs that are currently being studied in clinical trials for MASLD or MASH.

Preventive role of Pastinaca sativa in mitigating metabolic dysfunction-associated steatotic liver disease via modulation of metabolic endotoxemia

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a leading global liver disorder. Parsnip (Pastinaca sativa), rich in dietary fiber and medicinal properties, has shown health benefits, but its effects on MASLD are largely unexplored. This study evaluated the prebiotic and anti-MASLD effects of parsnip root water-soluble extract (PRE) in a mouse model. Mice fed a high-fat diet with 50 or 100 mg/kg PRE for eight weeks showed reduced fat accumulation, improved serum metabolic profiles, and decreased liver injury markers. PRE also lowered hepatic lipogenic protein levels induced by the high-fat diet. Additionally, PRE enhanced gut health by reducing endotoxins, improving intestinal permeability, and upregulating tight junction proteins. These results indicate that PRE can improve gut health, prevent MASLD, and support its potential as a dietary supplement to enhance metabolic health.

The Role of Diet, Additives, and Antibiotics in Metabolic Endotoxemia and Chronic Diseases

Background/Objectives: Dietary patterns, including high-fat and high-carbohydrate diets (HFDs and HCDs), as well as non-dietary factors such as food additives and antibiotics, are strongly linked to metabolic endotoxemia, a critical driver of low-grade chronic inflammation. This review explores the mechanisms through which these factors impair intestinal permeability, disrupt gut microbial balance, and facilitate lipopolysaccharide (LPS) translocation into the bloodstream, contributing to metabolic disorders such as obesity, type 2 diabetes mellitus, and inflammatory bowel disease. Methods: The analysis integrates findings from recent studies on the effects of dietary components and gut microbiota interactions on intestinal barrier function and systemic inflammation. Focus is given to experimental designs assessing gut permeability using biochemical and histological methods, alongside microbiota profiling in both human and animal models. Results: HFDs and HCDs were shown to increase intestinal permeability and systemic LPS levels, inducing gut dysbiosis and compromising barrier integrity. The resulting endotoxemia promoted a state of chronic inflammation, disrupting metabolic regulation and contributing to the pathogenesis of various metabolic diseases. Food additives and antibiotics further exacerbated these effects by altering microbial composition and increasing gut permeability. Conclusions: Diet-induced alterations in gut microbiota and barrier dysfunction emerge as key mediators of metabolic endotoxemia and related disorders. Addressing dietary patterns and their impact on gut health is crucial for developing targeted interventions. Further research is warranted to standardize methodologies and elucidate mechanisms for translating these findings into clinical applications.

Novel perspectives on the link between obesity and cancer risk: from mechanisms to clinical implications

Existing epidemiologic and clinical studies have demonstrated that obesity is associated with the risk of a variety of cancers. In recent years, an increasing number of experimental and clinical studies have unraveled the complex relationship between obesity and cancer risk and the underlying mechanisms. Obesity-induced abnormalities in immunity and biochemical metabolism, including chronic inflammation, hormonal disorders, dysregulation of adipokines, and microbial dysbiosis, may be important contributors to cancer development and progression. These contributors play different roles in cancer development and progression at different sites. Lifestyle changes, weight loss medications, and bariatric surgery are key approaches for weight-centered, obesity-related cancer prevention. Treatment of obesity-related inflammation and hormonal or metabolic dysregulation with medications has also shown promise in preventing obesity-related cancers. In this review, we summarize the mechanisms through which obesity affects the risk of cancer at different sites and explore intervention strategies for the prevention of obesity-associated cancers, concluding with unresolved questions and future directions regarding the link between obesity and cancer. The aim is to provide valuable theoretical foundations and insights for the in-depth exploration of the complex relationship between obesity and cancer risk and its clinical applications.

Garcinol enriched fraction of Garcinia morella (Gaertn.) Desr. fruit rind improves gut health and reduces the risk of nonalcoholic fatty liver disease by regulating PCK1/ACC/SREBP1/FASn pathway in a mouse model

Nonalcoholic fatty liver disease (NAFLD), a fast-emerging global burden, is an umbrella term for several liver manifestations that result in excessive accumulation of fat in the liver. NAFLD leads to gut microbiome dysbiosis, loss in gut epithelia, increased gut permeability, etc. The limited availability of registered drugs for NAFLD highlights the urgent need to focus on understanding its pathogenesis and discovering new treatments, including the potential exploration of herbal therapies for managing the condition. In this study, we evaluated the bioactive potential of garcinol enriched fraction from Garcinia morella fruit rind in preventing NAFLD-associated increased gut permeability. Administration of garcinol-enriched fraction (GEF) significantly reduced body weight, serum lipids (triglyceride and total cholesterol) levels, and enzymes (alkaline phosphatase and aspartate aminotransferase) responsible for liver dysfunction in high-fat diet (HFD)-fed C57BL/6 mice. GEF treatment also regulated the alteration in signaling pathways of lipid metabolism in HFD-fed mice by inhibiting the overexpression of genes involved in de novo lipogenesis. Mice treated with GEF had increased gut microbial diversity, reduced pathogenic bacteria, and increased Lactococcus and Streptococcaceae genera. Additionally, GEF treatment could increase the expression of intestinal tight junction proteins, which were otherwise decreased in HFD-fed mice, stipulating its protective effect in maintaining gut barrier integrity. Our study demonstrated that GEF treatment reduces obesity in mice and improves gut health by keeping junctions tight and maintaining a healthy gut microbiome.

Unraveling the Role of the Human Gut Microbiome in Health and Diseases

The human gut is a complex ecosystem that supports billions of living species, including bacteria, viruses, archaea, phages, fungi, and unicellular eukaryotes. Bacteria give genes and enzymes for microbial and host-produced compounds, establishing a symbiotic link between the external environment and the host at both the gut and systemic levels. The gut microbiome, which is primarily made up of commensal bacteria, is critical for maintaining the healthy host's immune system, aiding digestion, synthesizing essential nutrients, and protecting against pathogenic bacteria, as well as influencing endocrine, neural, humoral, and immunological functions and metabolic pathways. Qualitative, quantitative, and/or topographic shifts can alter the gut microbiome, resulting in dysbiosis and microbial dysfunction, which can contribute to a variety of noncommunicable illnesses, including hypertension, cardiovascular disease, obesity, diabetes, inflammatory bowel disease, cancer, and irritable bowel syndrome. While most evidence to date is observational and does not establish direct causation, ongoing clinical trials and advanced genomic techniques are steadily enhancing our understanding of these intricate interactions. This review will explore key aspects of the relationship between gut microbiota, eubiosis, and dysbiosis in human health and disease, highlighting emerging strategies for microbiome engineering as potential therapeutic approaches for various conditions.

Lactobacillus plantarum KAD protects against high-fat diet-induced hepatic complications in Swiss albino mice: Role of inflammation and gut integrity

Hepatic complications are the major health issues associated with dietary intake of calorie saturated food e.g. high-fat diet (HFD). Recent studies have revealed the beneficial effects of probiotics in HFD fed mice with hepatic complications. Some probiotic Lactic acid bacteria (LAB) e.g. Lactobacillus plantarum have drawn our attention in managing hepatic complications. Here, we aim to elucidate the protective effects of L. plantarum KAD strain, isolated from ethnic fermented food 'Kinema' in HFD-fed mice as, a preventive approach. Eighteen Swiss albino mice were equally divided into 3 groups: Normal Diet (ND), negative control (HFD), and HFD-fed with oral L. plantarum KAD supplementation (LP). All the experimental groups were subjected to specific diet according to grouping for eight weeks. After completion of the regime, subjects were anesthetized and sacrificed. Organs, blood, and fecal samples were collected and stored appropriately. Physical indices, including body weight gain, organ co-efficients were calculated along with assessment of glycemic, lipidomic, hepatic, oxidative stress, inflammatory, and histological parameters. Gut microbiota analysis was performed using 16s V3-V4 fecal metagenomic profiling, and sequencing were done using Illumina Miseq system. Oral administration of L. plantarum KAD is found to significantly (p<0.05) restore metabolic health by normalizing glycemic, lipidomic, hepatic parameters, oxidative stress and inflammatory parameters. Moreover, LP group (7.08±0.52 mg/g) showed significantly (p<0.001) decreased hepatic triglyceride level compared to HFD group (20.07±1.32 mg/g). L. plantarum KAD improved the adipocytic, and colonic histomorphology with significantly better scoring pattern. LP group (1.83±0.41) showed a significantly (p<0.001) reduced hepatic score compared to negative control group (5.00±0.63), showing reduced hepatosteatosis, and immune infiltration. The strain modulated gut health by altering its microbial composition positively towards normalization. In conclusion, the results of the experiment suggest that prophylactic L. plantarum KAD administration has beneficial effects on the onset of HFD induced hepatic complications in mice. Further studies are needed, on this strain for its clinical use as dietary supplement.

Role of the Gut Microbiome in Metabolic Dysfunction-Associated Steatotic Liver Disease

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD)-previously described as nonalcoholic fatty liver disease-continues to rise globally. Despite this, therapeutic measures for MASLD remain limited. Recently, there has been a growing interest in the gut microbiome's role in the pathogenesis of MASLD. Understanding this relationship may allow for the administration of therapeutics that target the gut microbiome and/or its metabolic function to alleviate MASLD development or progression. This review will discuss the interplay between the gut microbiome's structure and function in relation to the development of MASLD, assess the diagnostic yield of gut microbiome-based signatures as a noninvasive tool to identify MASLD severity, and examine current and emerging therapies targeting the gut microbiome-liver axis.

Role of gut microbiota and immune cells in metabolic-associated fatty liver disease: clinical impact

In 2020, a revised definition of fatty liver disease associated with metabolic dysfunction (MAFLD) was proposed to replace non-alcoholic fatty liver (NAFLD). Liver steatosis and at least one of the three metabolic risk factors, including type 2 diabetes, obesity, or signs of metabolic dysregulation, are used to diagnose MAFLD. MAFLD, similarly to NAFLD, is characterized by a spectrum of disease ranging from simple steatosis to advanced metabolic steatohepatitis with or without fibrosis, and may progress to cirrhosis and liver cancer, including increased risk of other critical extrahepatic diseases. Even though the pathophysiology of MAFLD and potential therapeutic targets have been explored in great detail, there is yet no Food and Drug Administration approved treatment. Recently, gut microbiome-derived products (e.g., endotoxins and metabolites) involved in intestinal barrier disruption, systemic inflammation, and modification of intrahepatic immunity have been associated with MAFLD development and progression. Therefore, different strategies could be adopted to modify the gut microbiome to improve outcomes in early and progressive MAFLD. Here, we provide an overview of mechanisms that may link the gut microbiome and immune response during the onset of liver steatosis and progression to steatohepatitis and fibrosis in patients with MAFLD. Finally, gut microbiota-based approaches are discussed as potential personalized treatments against MAFLD.

Tauroursodeoxycholic Acid Improves Nonalcoholic Fatty Liver Disease by Regulating Gut Microbiota and Bile Acid Metabolism

Tauroursodeoxycholic acid (TUDCA) is a synthetic bile salt that has demonstrated efficacy in the management of hepatobiliary disorders. However, its specific mechanism of action in preventing and treating nonalcoholic fatty liver disease (NAFLD) remains incompletely understood. This research revealed that TUDCA treatment can reduce obesity and hepatic lipid buildup, enhance intestinal barrier function and microbial balance, and increase the presence of Allobaculum and Bifidobacterium in NAFLD mouse models. TUDCA can influence the activity of farnesoid X receptor (FXR) and cholesterol 7α-hydroxylase (CYP7A1), resulting in higher hepatic bile acid levels and increased expression of sodium taurocholate cotransporting polypeptide (NTCP), leading to elevated concentrations of liver-bound bile acids in mice. Furthermore, TUDCA can inhibit the expression of FXR and fatty acid transport protein 5 (FATP5), thereby reducing fatty acid absorption and hepatic lipid accumulation. This investigation provides new insights into the potential of TUDCA for preventing and treating NAFLD.

The lipopolysaccharide-TLR4 axis regulates hepatic glutaminase 1 expression promoting liver ammonia build-up as steatotic liver disease progresses to steatohepatitis

INTRODUCTION

Ammonia is a pathogenic factor implicated in the progression of metabolic-associated steatotic liver disease (MASLD). The contribution of the glutaminase 1 (GLS) isoform, an enzyme converting glutamine to glutamate and ammonia, to hepatic ammonia build-up and the mechanisms underlying its upregulation in metabolic-associated steatohepatitis (MASH) remain elusive.

METHODS

Multiplex transcriptomics and targeted metabolomics analysis of liver biopsies in dietary mouse models representing the whole spectra of MASLD were carried out to characterize the relevance of hepatic GLS during disease pathological progression. In addition, the acute effect of liver-specific GLS inhibition in hepatic ammonia content was evaluated in cultured hepatocytes and in in vivo mouse models of diet-induced MASLD. Finally, the regulatory mechanisms of hepatic GLS overexpression related to the lipopolysaccharide (LPS)/Toll-like receptor 4 (TLR4) axis were explored in the context of MASH.

RESULTS

In mouse models of diet-induced MASLD, we found that augmented liver GLS expression is closely associated with the build-up of hepatic ammonia as the disease progresses from steatosis to steatohepatitis. Importantly, the acute silencing/pharmacological inhibition of GLS diminishes the ammonia burden in cultured primary mouse hepatocytes undergoing dedifferentiation, in steatotic hepatocytes, and in a mouse model of diet-induced steatohepatitis, irrespective of changes in ureagenesis and gut permeability. Under these conditions, GLS upregulation in the liver correlates positively with the hepatic expression of TLR4 that recognizes LPS. In agreement, the pharmacological inhibition of TLR4 reduces GLS and hepatic ammonia content in LPS-stimulated mouse hepatocytes and hyperammonemia animal models of endotoxemia.

CONCLUSIONS

Overall, our results suggest that the LPS/TLR4 axis regulates hepatic GLS expression promoting liver ammonia build-up as steatotic liver disease progresses to steatohepatitis.

Revealing the lethal effects of Pasteurella multocida toxin on multiple organ systems

Pasteurella multocida toxin (PMT) is one of the most important virulence factors of Pasteurella multocida type D. Pasteurella multocida infection has caused enormous economic losses in the pig farming industry. Although it is well known that this bacterial infection causes progressive atrophic rhinitis, its effects on other organ tissues in pigs are unclear. In this study, PMT was expressed and purified, and the cytotoxic effects of PMT on four types of swine cells, LLC-PK1, PAM, IPEC, and ST, were investigated. LLC-PK1 exhibited the highest sensitivity to the cytotoxic effects of PMT. Our studies revealed that a PMT concentration of 0.1 μg/kg can lead to weight loss, whereas a PMT concentration of 0.5 μg/kg can lead to death in mice. PMT causes damage to the intestines, kidneys, lungs, livers, and spleens of mice. Furthermore, PMT caused acute death in pigs at treatment concentrations greater than 5 μg/kg; at PMT concentration of 2.5 μg/kg, weight loss occurred until death. PMT mainly caused damage to the hearts, lungs, livers, spleens and kidneys of pigs. The organ coefficient showed that damage to the heart and kidneys was the most severe and caused the renal pelvis and renal pyramid to dissolve and become cavitated. Pathology revealed hemorrhage in the lungs, liver, and spleen, and the kidneys were swollen and vacuolated, which was consistent with the damaged target organs in the mice. In conclusion, these findings demonstrate that PMT is extremely toxic in vitro and in vivo, causing damage to various organs of the body, especially the kidneys and lungs. This study provides a theoretical basis for the in-depth exploration of the cytotoxic effects of PMT on target organs.

High-altitude hypoxia promotes BRD4-mediated activation of the Wnt/β-catenin pathway and disruption of intestinal barrier

Hypobaric hypoxia, commonly experienced at elevated altitudes, presents significant physiological challenges. Our investigation is centered on the impact of the bromodomain protein 4 (BRD4) under these conditions, especially its interaction with the Wnt/β-Catenin pathway and resultant effects on glycolytic inflammation and intestinal barrier stability. By combining transcriptome sequencing with bioinformatics, we identified BRD4's key role in hypoxia-related intestinal anomalies. Clinical parameters of altitude sickness patients, including serum BRD4 levels, inflammatory markers, and barrier integrity metrics, were scrutinized. In vitro studies using CCD 841 CoN cells depicted expression changes in BRD4, Interleukin (IL)-1β, IL-6, and β-Catenin. Transepithelial electrical resistance (TEER) and FD4 analyses assessed barrier resilience. Hypoxia-induced mouse models, analyzed via H&E staining and Western blot, provided insights into barrier and protein alterations. Under hypoxic conditions, marked BRD4 expression variations emerged. Elevated serum BRD4 in patients coincided with intensified Wnt signaling, inflammation, and barrier deterioration. In vitro, findings showed hypoxia-induced upregulation of BRD4 and inflammatory markers but a decline in Occludin and ZO1, affecting barrier strength-effects mitigated by BRD4 inhibition. Mouse models echoed these patterns, linking BRD4 upregulation in hypoxia to barrier perturbations. Hypobaric hypoxia-induced BRD4 upregulation disrupts the Wnt/β-Catenin signaling, sparking glycolysis-fueled inflammation and weakening intestinal tight junctions and barrier degradation.

Advances in the understanding of nuclear pore complexes in human diseases

BACKGROUND

Nuclear pore complexes (NPCs) are sophisticated and dynamic protein structures that straddle the nuclear envelope and act as gatekeepers for transporting molecules between the nucleus and the cytoplasm. NPCs comprise up to 30 different proteins known as nucleoporins (NUPs). However, a growing body of research has suggested that NPCs play important roles in gene regulation, viral infections, cancer, mitosis, genetic diseases, kidney diseases, immune system diseases, and degenerative neurological and muscular pathologies.

PURPOSE

In this review, we introduce the structure and function of NPCs. Then We described the physiological and pathological effects of each component of NPCs which provide a direction for future clinical applications.

METHODS

The literatures from PubMed have been reviewed for this article.

CONCLUSION

This review summarizes current studies on the implications of NPCs in human physiology and pathology, highlighting the mechanistic underpinnings of NPC-associated diseases.

Immunobiotic Bacteria Attenuate Hepatic Fibrosis through the Modulation of Gut Microbiota and the Activation of Aryl-Hydrocarbon Receptors Pathway in Non-Alcoholic Steatohepatitis Mice

SCOPE

Nonalcoholic steatohepatitis (NASH) is a leading cause of chronic liver disease worldwide that can progress to liver fibrosis (LF). Probiotics have beneficial roles in reducing intestinal inflammation and gut-associated diseases, but their effects and mechanisms beyond the gut in attenuating the progression of LF are remained unclear.

METHODS AND RESULTS

In a mouse model of NASH/LF induced by a methionine-choline deficient (MCD) diet, immunobiotics are administered to investigate their therapeutic effects. Results show that the MCD diet leads to liver inflammation, steatosis, and fibrosis, which are alleviated by immunobiotics. Immunobiotics reduces serum endotoxin and inflammatory markers while increasing regulatory cytokines and liver weight. They also suppress Th17 cells, known for producing inflammatory cytokines. Furthermore, immunobiotics mitigate collagen deposition and fibrogenic signaling in the liver, while restoring gut-barrier integrity and microbiota composition. Additionally, immunobiotics enhance the activation of the aryl hydrocarbon receptor (AhR) pathway in both colonic and liver tissues.

CONCLUSIONS

Overall, these results demonstrate a novel insight into the mechanisms through which immunobiotic administration improves the gut health which in turn increases the AhR pathway and inhibits HSCs activation and fibrosis progression beyond the gut in the liver tissue of NASH/LF mice.

Western diet components that increase intestinal permeability with implications on health

Intestinal permeability is a physiological property that allows necessary molecules to enter the organism. This property is regulated by tight junction proteins located between intestinal epithelial cells. However, various factors can increase intestinal permeability (IIP), including diet. Specific components in the Western diet (WD), such as monosaccharides, fat, gluten, salt, alcohol, and additives, can affect the tight junctions between enterocytes, leading to increased permeability. This review explains how these components promote IIP and outlines their potential implications for health. In addition, we describe how a reduction in WD consumption may help improve dietary treatment of diseases associated with IIP. Research has shown that some of these components can cause changes in the gut microbiota, leading to dysbiosis, which can promote greater intestinal permeability and displacement of endotoxins into the bloodstream. These endotoxins include lipopolysaccharides derived from gram-negative bacteria, and their presence has been associated with various diseases, such as autoimmune, neurological, and metabolic diseases like diabetes and cardiovascular disease. Therefore, nutrition professionals should promote the reduction of WD consumption and consider the inclusion of healthy diet components as part of the nutritional treatment for diseases associated with increased intestinal permeability.

Emerging drugs for the treatment of hepatic fibrosis on nonalcoholic steatohepatitis

INTRODUCTION

Approved drug therapies for nonalcoholic steatohepatitis (NASH) are lacking, for which various agents are currently being tested in clinical trials. Effective drugs for liver fibrosis, the factor most associated with prognosis in NASH, are important.

AREAS COVERED

This study reviewed the treatment of NASH with a focus on the effects of existing drugs and new drugs on liver fibrosis.

EXPERT OPINION

Considering the complex pathophysiology of fibrosis in NASH, drug therapy may target multiple pathways. The method of assessing fibrosis is important when considering treatment for liver fibrosis in NASH. The Food and Drug Administration considers an important fibrosis endpoint to be histological improvement in at least one fibrosis stage while preventing worsening of fatty hepatitis. To obtain approval as a drug for NASH, efficacy needs to be demonstrated on endpoints such as liver-related events and myocardial infarction. Among the current therapeutic agents for NASH, thiazolidinedione, sodium-glucose co-transporter 2, and selective peroxisome proliferator-activated receptors α modulator have been reported to be effective against fibrosis, although further evidence is required. The effects of pan-peroxisome proliferator-activated receptors, obeticholic acid, and fibroblast growth factor-21 analogs on liver fibrosis in the development stage therapeutics for NASH are of particular interest.

Immunology of gut microbiome and liver in non-alcoholic fatty liver disease (NAFLD): mechanisms, bacteria, and novel therapeutic targets

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world. Most important contributors to its development are diet and obesity. Gut microbiome's importance for immune system and inflammatory pathways more widely accepted as an important component in NAFLD and other liver diseases' pathogenesis. In this article we review potential mechanisms of microbiome alteration of local and systemic immune responses leading to NAFLD's development, and how can modulate them for the treatment. Our review mentions different immune system pathways and microorganisms regulating metabolism, liver inflammation and fibrosis. We specifically point out TLR-4 as a potential key immune pathway activated by bacterial lipopolysaccharides producing pro-inflammatory cytokines in NAFLD. Also, we discuss three endotoxin-producing strains (Enterobacter cloacae B29, Escherichia coli PY102, Klebsiella pneumoniae A7) that can promote NAFLD development via TLR4-dependent immune response activation in animal models and how they potentially contribute to disease progression in humans. Additionally, we discuss their other immune and non-immune mechanisms contributing to NAFLD pathogenesis. In the end we point out gut microbiome researches' future perspective in NAFLD as a potential new target for both diagnostic and treatment.

Akkermansia muciniphila and its outer membrane protein Amuc_1100 prevent high-fat diet-induced nonalcoholic fatty liver disease in mice

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease. A. muciniphila and its outer membrane protein Amuc_1100 ameliorate metabolic disorders, enteritis, depression, and other diseases in mice. The NAFLD mouse model was established by feeding a high-fat diet (HFD) for 10 weeks. To assess the effect of A. muciniphila and Amuc_1100 on NAFLD, we used atorvastatin, a common lipid-lowering drug, as a positive control. A. muciniphila and Amuc_1100 significantly reduced body weight and serum ALT and AST levels, and improved serum lipid levels in NAFLD mice, which had similar effects to Ator. In addition, A. muciniphila and Amuc_1100 decreased the concentration of LPS in the serum and upregulated the mRNA expression of the colonic tight junction proteins. In the liver, A. muciniphila and Amuc_1100 significantly reduced the mRNA expression levels of nodular receptor protein 3 (NLRP3) and Toll-like receptor 4 (TLR4)/nuclear factor κB (NF-κB), and the protein and mRNA expression levels inflammatory cytokines. At the genus level, Amuc_1100 treatment significantly reduced the abundance of Coriobacteriaceae_UCG-002 produced by the HFD. The abundances of Blautia, norank_f__Ruminococcaceae, Lachnoclostridium, GCA-900066575 and Lachnospiraceae_UCG-006 increased dramatically. Together, A. muciniphila and Amuc_1100 alleviate HFD-induced NAFLD by acting on the gut-liver axis and regulating gut microbes.

15-keto-PGE2 alleviates nonalcoholic steatohepatitis through its covalent modification of NF-κB factors

15-keto-PGE2 is one of the eicosanoids with anti-inflammatory properties. In this study, we demonstrated that 15-keto-PGE2 post-translationally modified the nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) subunits p105/p50 and p65 at Cys59 and Cys120 sites, respectively, hence inhibiting the activation of NF-κB signaling in macrophages. In mice fed a high-fat and high-sucrose diet (HFHSD), 15-keto-PGE2 treatment reduced pro-inflammatory cytokines and fasting glucose levels. In mice with non-alcoholic steatohepatitis (NASH) induced by a prolonged HFHSD, 15-keto-PGE2 treatment significantly decreased liver inflammation, lowered serum levels of alanine transaminase (ALT) and aspartate transferase (AST), and inhibited macrophage infiltration. It also reduced lipid droplet size and downregulated key regulators of lipogenesis. These findings highlight the potential of 15-keto-PGE2, through NF-κB modification, in preventing the development and progression of steatohepatitis, emphasizing the significance of endogenous lipid mediators in the inflammatory response.

Anti-inflammatory effects of probiotics and synbiotics on patients with non-alcoholic fatty liver disease: An umbrella study on meta-analyses

BACKGROUND AND AIM

The impact of chronic low-grade inflammation in the development of non-alcoholic fatty liver disease (NAFLD) has been studied widely. Previous studies showed gut pathogens' effects on inflammation development in NAFLD patients; hence, hypothetically, gut microbial therapy by administration of probiotics, synbiotics, and prebiotics may alleviate inflammation in these individuals. Several studies were performed in this regard; however, conflicting results were obtained. In this study, we aimed to comprehensively evaluate the effects of gut microbial therapy on inflammatory markers in NAFLD patients in a meta-umbrella design.

METHODS

Two independent researchers investigated international databases, including PubMed, Web of Science, Scopus, and Cochrane Library, from inception until March 2023. Meta-analyses evaluating the impact of probiotics, synbiotics, or prebiotics on inflammatory markers of patients with NAFLD were eligible for our study. AMASTAR 2 checklist was used to evaluate the quality of included studies. Random effect model was performed for the analysis, and Egger's regression test was conducted to determine publication bias.

RESULTS

A total number of 12 studies were entered into our analysis. Our findings revealed that gut microbial therapy could significantly reduce serum C-reactive protein (CRP) levels among NAFLD patients (ES: -0.58; 95% CI: -0.73, -0.44, P < 0.001). In subgroup analysis, this reduction was observed with both probiotics (ES: -0.63; 95% CI: -0.81, -0.45, P < 0.001) and synbiotics (ES: -0.49; 95% CI: -0.74, -0.24, P < 0.001). In addition, gut microbial therapy could significantly decrease tumor necrosis factor-a (TNF-a) levels in NAFLD patients (ES: -0.48; 95% CI: -0.67 to -0.30, P < 0.001). In subgroup analysis, this decrease was observed with probiotics (ES: -0.32; 95% CI: -0.53, -0.11, P = 0.002) and synbiotics (ES: -0.96; 95% CI: -1.32, -0.60, P < 0.001). Not enough information was available for assessing prebiotics' impacts.

CONCLUSION

The results of this umbrella review suggest that probiotics and synbiotics have promising effects on inflammatory markers, including TNF-a and CRP; however, more research is needed regarding the effects of prebiotics.

PROSPERO REGISTRATION CODE

CRD42022346998.

Blood Endotoxin Levels as Biomarker of Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Growing evidence supports a role of gut-derived metabolites in nonalcoholic fatty liver disease (NAFLD), but the relation of endotoxin levels with gut permeability and NAFLD stage remains unclear. This systematic review with meta-analysis aims to provide further insights.

METHODS

PubMed, Embase, and Cochrane Library were searched for studies published until January 2022 assessing blood endotoxins in patients with NAFLD. Meta-analyses and univariate/multivariate meta-regression, as well as correlation analyses, were performed for endotoxin values and potential relationships to disease stage, age, sex, parameters of systemic inflammation, and metabolic syndrome, as well as liver function and histology.

RESULTS

Forty-three studies were included, of which 34 were used for meta-analyses. Blood endotoxin levels were higher in patients with simple steatosis vs liver-healthy controls (standardized mean difference, 0.86; 95% confidence interval, 0.62-1.11) as well as in patients with nonalcoholic steatohepatitis vs patients with nonalcoholic fatty liver/non-nonalcoholic steatohepatitis (standardized mean difference, 0.81; 95% confidence interval, 0.27-1.35; P = .0078). Consistently, higher endotoxin levels were observed in patients with more advanced histopathological gradings of liver steatosis and fibrosis. An increase of blood endotoxin levels was partially attributed to a body mass index rise in patients with NAFLD compared with controls. Nevertheless, significant increases of blood endotoxin levels in NAFLD retained after compensation for differences in body mass index, metabolic condition, or liver enzymes. Increases in blood endotoxin levels were associated with increases in C-reactive protein concentrations, and in most cases, paralleled a rise in markers for intestinal permeability.

CONCLUSION

Our results support blood endotoxin levels as relevant diagnostic biomarker for NAFLD, both for disease detection as well as staging during disease progression, and might serve as surrogate marker of enhanced intestinal permeability in NAFLD. Registration number in Prospero: CRD42022311166.

DNMT3B Alleviates Liver Steatosis Induced by Chronic Low-grade LPS via Inhibiting CIDEA Expression

BACKGROUND & AIMS

Nonalcoholic fatty liver disease is the most prevalent chronic liver disease and threats to human health. Gut dysbiosis caused by lipopolysaccharide (LPS) leakage has been strongly related to nonalcoholic fatty liver disease progression, although the underlying mechanisms remain unclear.

METHODS

Previous studies have shown that low-grade LPS administration to mice on a standard, low-fat chow diet is sufficient to induce symptoms of fatty liver. This study confirmed these findings and supported LPS as a lipid metabolism regulator in the liver.

RESULTS

Mechanically, LPS induced dysregulated lipid metabolism by inhibiting the expression of DNA methyltransferases 3B (DNMT3B). Genetic overexpression of DNMT3B alleviated LPS-induced lipid accumulation, whereas its knockdown increased steatosis in mice and human hepatocytes. LPS-induced lower expression of DNMT3B led to hypomethylation in promoter region of CIDEA, resulting in increased binding of SREBP-1c to its promoter and activated CIDEA expression. Hepatic interference of CIDEA reversed the effect of LPS on lipogenesis. These effects were independent of a high-fat diet or high fatty acid action.

CONCLUSIONS

Overall, these findings sustain the conclusion that LPS is a lipogenic factor and could be involved in hepatic steatosis progression.

Pneumosepsis survival in the setting of obesity leads to persistent steatohepatitis and metabolic dysfunction

BACKGROUND

As critical care practice evolves, the sepsis survivor population continues to expand, often with lingering inflammation in many organs, including the liver. Given the concurrently increasing population of patients with NAFLD, in this study, we aimed to understand the long-term effect of sepsis on pre-existing NAFLD and hyperglycemia.

METHODS

Male mice were randomized to a high-fat diet or a control diet (CD). After 24 weeks on diet, mice were inoculated with Klebsiella pneumoniae (Kpa). Serial glucose tolerance tests, and insulin and pyruvate challenge tests were performed 1 week before infection and at 2 and 6 weeks after infection. Whole tissue RNA sequencing and histological evaluation of the liver were performed. To test whether persistent inflammation could be reproduced in other abnormal liver environments, mice were also challenged with Kpa after exposure to a methionine-choline-deficient high-fat diet. Finally, a retrospective cohort of 65,139 patients was analyzed to evaluate whether obesity was associated with liver injury after sepsis.

RESULTS

After Kpa inoculation, high-fat diet mice had normalized fasting blood glucose without a change in insulin sensitivity but with a notable decrease in pyruvate utilization. Liver examination revealed focal macrophage collections and a unique inflammatory gene signature on RNA analysis. In the clinical cohort, preobesity, and class 1 and class 2 obesity were associated with increased odds of elevated aminotransferase levels 1-2 years after sepsis.

CONCLUSIONS

The combination of diet-induced obesity and pneumosepsis survival in a murine model resulted in unique changes in gluconeogenesis and liver inflammation, consistent with the progression of benign steatosis to steatohepatitis. In a cohort study, obese patients had an increased risk of elevated aminotransferase levels 1-2 years following sepsis.

Nutritional Support for Liver Diseases

The liver is a key organ that is responsible for the metabolism of proteins, fats, and carbohydrates and the absorption and storage of micronutrients. Unfortunately, the prevalence of chronic liver diseases at various stages of advancement in the world population is significant. Due to the physiological function of the liver, its dysfunction can lead to malnutrition and sarcopenia, and the patient's nutritional status is an important prognostic factor. This review discusses key issues related to the diet therapy of patients with chronic liver diseases, as well as those qualified for liver transplantation and in the postoperative period.

NAFLD and AATD Are Two Diseases with Unbalanced Lipid Metabolism: Similarities and Differences

Non-alcoholic fatty liver disease (NAFLD) is a type of steatosis commonly associated with obesity, dyslipidemia, hypertension, and diabetes. Other diseases such as inherited alpha-1 antitrypsin deficiency (AATD) have also been related to the development of liver steatosis. The primary reasons leading to hepatic lipid deposits can be genetic and epigenetic, and the outcomes range from benign steatosis to liver failure, as well as to extrahepatic diseases. Progressive hepatocellular damage and dysregulated systemic immune responses can affect extrahepatic organs, specifically the heart and lungs. In this review, we discuss the similarities and differences between the molecular pathways of NAFLD and AATD, and the putative value of hepatic organoids as novel models to investigate the physio pathological mechanisms of liver steatosis.

Role of CD14 in human disease

The cell surface antigen CD14 is primarily understood to act as a co-receptor for toll-like receptors (TLRs) to activate innate immunity responses to pathogens and tissue injury in macrophages and monocytes. However, roles for CD14 are increasingly being uncovered in disease responses in epithelial and endothelial cells. Consistent with these broader functions, CD14 expression is altered in a variety of non-immune cell types in response to a several of disease states. Moreover, soluble CD14 activated by factors from both pathogens and tissue damage may initiate signalling in a variety of non-immune cells. This review examined the current understanding CD14 in innate immunity as well as its potential functions in nonimmune cells and associated human diseases.

Non-target GC-MS analyses of fecal VOCs in NASH-hepatocellular carcinoma model STAM mice

The increased incidence of obesity in the global population has increased the risk of several chronic inflammation-related diseases, including non-alcoholic steatohepatitis (NASH)-hepatocellular carcinoma (HCC). The progression from NASH to HCC involves a virus-independent liver carcinogenic mechanism; however, we currently lack effective treatment and prevention strategies. Several reports have suggested that fecal volatile organic compounds (VOCs) are strongly associated with NASH-HCC; therefore, we explored the biomarkers involved in its pathogenesis and progression. Fecal samples collected from control and NASH-HCC model STAM mice were subjected to headspace autosampler gas chromatography-electron ionization-mass spectrometry. Non-target profiling analysis identified diacetyl (2,3-butandione) as a fecal VOC that characterizes STAM mice. Although fecal diacetyl levels were correlated with the HCC in STAM mice, diacetyl is known as a cytotoxic/tissue-damaging compound rather than genotoxic or mutagenic; therefore, we examined the effect of bioactivity associated with NASH progression. We observed that diacetyl induced several pro-inflammatory molecules, including tumor necrosis factor-α, cyclooxygenase-2, monocyte chemoattractant protein-1, and transforming growth factor-β, in mouse macrophage RAW264.7 and Kupffer KPU5 cells. Additionally, we observed that diacetyl induced α-smooth muscle actin, one of the hallmarks of fibrosis, in an ex vivo cultured hepatic section, but not in in vitro hepatic stellate TWNT-1 cells. These results suggest that diacetyl would be a potential biomarker of fecal VOC in STAM mice, and its ability to trigger the macrophage-derived inflammation and fibrosis may partly contribute to NASH-HCC carcinogenesis.

Molecular Mechanisms of Western Diet-Induced Obesity and Obesity-Related Carcinogenesis-A Narrative Review

The present study aims to provide a narrative review of the molecular mechanisms of Western diet-induced obesity and obesity-related carcinogenesis. A literature search of the Cochrane Library, Embase and Pubmed databases, Google Scholar and the grey literature was conducted. Most of the molecular mechanisms that induce obesity are also involved in the twelve Hallmarks of Cancer, with the fundamental process being the consumption of a highly processed, energy-dense diet and the deposition of fat in white adipose tissue and the liver. The generation of crown-like structures, with macrophages surrounding senescent or necrotic adipocytes or hepatocytes, leads to a perpetual state of chronic inflammation, oxidative stress, hyperinsulinaemia, aromatase activity, activation of oncogenic pathways and loss of normal homeostasis. Metabolic reprogramming, epithelial mesenchymal transition, HIF-1α signalling, angiogenesis and loss of normal host immune-surveillance are particularly important. Obesity-associated carcinogenesis is closely related to metabolic syndrome, hypoxia, visceral adipose tissue dysfunction, oestrogen synthesis and detrimental cytokine, adipokine and exosomal miRNA release. This is particularly important in the pathogenesis of oestrogen-sensitive cancers, including breast, endometrial, ovarian and thyroid cancer, but also 'non-hormonal' obesity-associated cancers such as cardio-oesophageal, colorectal, renal, pancreatic, gallbladder and hepatocellular adenocarcinoma. Effective weight loss interventions may improve the future incidence of overall and obesity-associated cancer.

Major roles of kupffer cells and macrophages in NAFLD development

Non-alcoholic fatty liver disease (NAFLD) is an important public health problem with growing numbers of NAFLD patients worldwide. Pathological conditions are different in each stage of NAFLD due to various factors. Preclinical and clinical studies provide evidence for a crucial role of immune cells in NAFLD progression. Liver-resident macrophages, kupffer cells (KCs), and monocytes-derived macrophages are the key cell types involved in the progression of NAFLD, non-alcoholic steatohepatitis (NASH), and hepatocellular carcinoma (HCC). Their unique polarization contributes to the progression of NAFLD. KCs are phagocytes with self-renewal abilities and play a role in regulating and maintaining homeostasis. Upon liver damage, KCs are activated and colonized at the site of the damaged tissue. The secretion of inflammatory cytokines and chemokines by KCs play a pivotal role in initiating NAFLD pathogenesis. This review briefly describes the role of immune cells in the immune system in NAFLD, and focuses on the pathological role and molecular pathways of KCs and recruited macrophages. In addition, the relationship between macrophages and insulin resistance is described. Finally, the latest therapeutics that target KCs and macrophages are summarized for the prevention and treatment of NAFLD.

From Non-Alcoholic Fatty Liver to Hepatocellular Carcinoma: A Story of (Mal)Adapted Mitochondria

Non-alcoholic fatty liver disease (NAFLD) is a global pandemic affecting 25% of the world's population and is a serious health and economic concern worldwide. NAFLD is mainly the result of unhealthy dietary habits combined with sedentary lifestyle, although some genetic contributions to NAFLD have been documented. NAFLD is characterized by the excessive accumulation of triglycerides (TGs) in hepatocytes and encompasses a spectrum of chronic liver abnormalities, ranging from simple steatosis (NAFL) to steatohepatitis (NASH), significant liver fibrosis, cirrhosis, and hepatocellular carcinoma. Although the molecular mechanisms that cause the progression of steatosis to severe liver damage are not fully understood, metabolic-dysfunction-associated fatty liver disease is strong evidence that mitochondrial dysfunction plays a significant role in the development and progression of NAFLD. Mitochondria are highly dynamic organelles that undergo functional and structural adaptations to meet the metabolic requirements of the cell. Alterations in nutrient availability or cellular energy needs can modify mitochondria formation through biogenesis or the opposite processes of fission and fusion and fragmentation. In NAFL, simple steatosis can be seen as an adaptive response to storing lipotoxic free fatty acids (FFAs) as inert TGs due to chronic perturbation in lipid metabolism and lipotoxic insults. However, when liver hepatocytes' adaptive mechanisms are overburdened, lipotoxicity occurs, contributing to reactive oxygen species (ROS) formation, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress. Impaired mitochondrial fatty acid oxidation, reduction in mitochondrial quality, and disrupted mitochondrial function are associated with a decrease in the energy levels and impaired redox balance and negatively affect mitochondria hepatocyte tolerance towards damaging hits. However, the sequence of events underlying mitochondrial failure from steatosis to hepatocarcinoma is still yet to be fully clarified. This review provides an overview of our understanding of mitochondrial adaptation in initial NAFLD stages and highlights how hepatic mitochondrial dysfunction and heterogeneity contribute to disease pathophysiology progression, from steatosis to hepatocellular carcinoma. Improving our understanding of different aspects of hepatocytes' mitochondrial physiology in the context of disease development and progression is crucial to improving diagnosis, management, and therapy of NAFLD/NASH.

Endotoxin Tolerance Acquisition and Altered Hepatic Fatty Acid Profile in Aged Mice

(1) Background: Aging is linked to an altered immune response and metabolism. Inflammatory conditions, such as sepsis, COVID-19, and steatohepatitis are more prevalent in the elderly and steatosis is linked both to severe COVID-19 and sepsis. We hypothesized that aging is linked to a loss of endotoxin tolerance, which normally protects the host from excessive inflammation, and that this is accompanied by elevated levels of hepatic lipids. (2) Methods: An in vivo lipopolysaccharide (LPS) tolerance model in young and old mice was used and the cytokine serum levels were measured by ELISA. Cytokine and toll-like receptor gene expression was determined by qPCR in the lungs and the liver; hepatic fatty acid composition was assessed by GC–MS. (3) Results: The old mice showed a distinct potential for endotoxin tolerance as suggested by the serum cytokine levels and gene expression in the lung tissue. Endotoxin tolerance was less pronounced in the livers of the aged mice. However, the fatty acid composition strongly differed in the liver tissues of the young and old mice with a distinct change in the ratio of C18 to C16 fatty acids. (4) Conclusions: Endotoxin tolerance is maintained in advanced age, but changes in the metabolic tissue homeostasis may lead to an altered immune response in old individuals.

The Association between Advanced Liver Fibrosis and Mortality Is Modified by Dietary Quality among Korean Adults: Results from the Korea National Health and Nutrition Examination Survey with Mortality Data

Advanced fibrosis in nonalcoholic fatty liver disease (NAFLD) is associated with an increased risk of mortality; however, an independent association of liver fibrosis with mortality is not well defined. We aimed to investigate the association between advanced liver fibrosis and all-cause and cardiovascular mortality and the mediation effect of diet quality. We analyzed 35,531 participants with suspected NAFLD, excluding competing etiologies of chronic liver disease, from the Korea National Health and Nutrition Examination Survey 2007-2015, and followed up until 31 December 2019. The severity of liver fibrosis was assessed using the NAFLD fibrosis score (NFS) and the fibrosis-4 index (FIB-4). The Cox proportional hazards model was used to examine the association of advanced liver fibrosis with mortality. During a mean 8.1 years of follow-up, 3426 deaths occurred. Advanced liver fibrosis determined by NFS and FIB-4 was associated with increased risks of all-cause and cardiovascular mortality after adjusting for confounders. When NFS and FIB-4 were combined, the high NFS + high FIB-4 group was significantly associated with higher risks of all-cause mortality (hazard ratio [HR] 1.85, 95% CI 1.42-2.43) and cardiovascular mortality (HR 2.04, 95% CI 1.23-3.39), respectively, compared with the low NFS + low FIB-4 group. However, these associations were attenuated in people with high diet quality. Advanced liver fibrosis is an independent risk factor for all-cause and cardiovascular mortality in people with NAFLD, and the association between advanced liver fibrosis and mortality is modified by a high-quality diet.

Hepatotoxicity of polymeric proanthocyanidins is caused by translocation of bacterial lipopolysaccharides through impaired gut epithelium

Polymeric proanthocyanidins (P-PAC) induced hepatotoxicity in C57BL/6 mice. Mice were supplemented with P-PAC alone or with a mixture of probiotic bacteria (PB), Lactobacillus, Bifidobacterium, and Akkermansia muciniphila for 14 consecutive days. The liver tissues of sacrificed mice were analyzed by mass spectrometry to identify and quantify the P-PAC metabolites. Potential P-PAC metabolites, 2-hydroxyphenylacetic acid and pyrocatechol were detected in higher concentrations and 4-hydroxybenzoic acid was detected exclusively in the mice supplemented with P-PAC and PB. Supplementation with P-PAC alone or with PB caused no shift in the α-diversity of mice gut microbiota. P-PAC induced nonalcoholic steatohepatitis in mice through increasing liver exposure to intestinal bacterial lipopolysaccharides by reducing expression of gut epithelial tight junction proteins, claudin-3 and occludin. Lipopolysaccharide concentrations in the livers of mice supplemented with P-PAC were significantly high compared to the control mice. Furthermore, P-PAC downregulated the expressions of claudin-3 and claudin-4 tight junction proteins in cultured Caco-2 cell monolayers. PB biotransformed P-PAC into bioavailable metabolites and potentially reduced the toxicity of P-PAC. The toxicity of P-PAC and their synbiotics need to be critically evaluated for the safety of human consumption.

Anti-Inflammatory and Gut Microbiota Modulating Effects of Probiotic Lactobacillus paracasei MSMC39-1 on Dextran Sulfate Sodium-Induced Colitis in Rats

Probiotics have been shown to possess several properties, depending on the strain. Some probiotics have important roles in preventing infection and balancing the immune system due to the interaction between the intestinal mucosa and cells in the immune system. This study aimed to examine the properties of three probiotic strains using the tumor necrosis factor-alpha (TNF-α) inhibition test in colorectal adenocarcinoma cells (Caco-2 cells). It was revealed that the viable cells and heat-killed cells of the probiotic L. paracasei strain MSMC39-1 dramatically suppressed TNF-α secretion in Caco-2 cells. The strongest strains were then chosen to treat rats with colitis induced by dextran sulfate sodium (DSS). Viable cells of the probiotic L. paracasei strain MSMC39-1 reduced aspartate transaminase and alanine transaminase in the serum and significantly inhibited TNF-α secretion in the colon and liver tissues. Treatment with the probiotic L. paracasei strain MSMC39-1 alleviated the colon and liver histopathology in DSS-induced colitis rats. Furthermore, supplementation with probiotic L. paracasei strain MSMC39-1 increased the genus Lactobacillus and boosted the other beneficial bacteria in the gut. Thus, the probiotic L. paracasei strain MSMC39-1 exhibited an anti-inflammation effect in the colon and modulated the gut microbiota.

High-fat diet increases mortality and intensifies immunometabolic changes in septic mice

Immunometabolic changes in the liver and white adipose tissue (WAT) caused by high-fat (HF) diet intake may worse metabolic adaptation and protection against pathogens in sepsis. We investigate the effect of chronic HF diet (15 weeks) on mortality and immunometabolic responses in female mice after sepsis induced by cecum ligation and perforation (CLP). At week 14, animals were divided into four groups: sham C diet (C-Sh), sepsis C diet (C-Sp), sham HF diet (HF-Sh) and sepsis HF diet (HF-Sp). The surviving animals were euthanised on the 7th day. The HF diet decreased survival rate (58.3% vs 76.2% C-Sp group), increased serum cytokine storm (IL-6 (1.41 ×; vs HF-Sh), IL-1β (1.37 ×; vs C-Sp), TNF (1.34 ×; vs C-Sp and 1.72 ×; vs HF-Sh), IL-17 (1.44 ×; vs HF-Sh), IL-10 (1.55 ×; vs C-Sp and 1.41 ×; HF-Sh), WAT inflammation (IL-6 (8.7 ×; vs C-Sp and 2.4 ×; vs HF-Sh), TNF (5 ×; vs C-Sp and 1.7 ×;vs HF-Sh), IL-17 (1.7 ×; vs C-Sp), IL-10 (7.4 ×; vs C-Sp and 1.3 ×; vs HF-Sh), and modulated lipid metabolism in septic mice. In the HF-Sp group liver's, we observed hepatomegaly, hydropic degeneration, necrosis, an increase in oxidative stress (reduction of CAT activity (-81.7%; vs HF-Sh); increase MDA levels (82.8%; vs HF-Sh), and hepatic IL-6 (1.9 ×; vs HF-Sh), and TNF (1.3 × %;vs HF-Sh) production. Furthermore, we found a decrease in the total number of inflammatory, mononuclear cells, and in the regenerative processes, and binucleated hepatocytes in a HF-Sp group liver's. Our results suggested that the organism under metabolic stress of a HF diet during sepsis may worsen the inflammatory landscape and hepatocellular injury and may harm the liver regenerative process.

Small Intestinal Bacterial Overgrowth and Non-Alcoholic Fatty Liver Disease: What Do We Know in 2023?

Non-alcoholic fatty liver disease (NAFLD) is a chronic liver disease associated with the pathological accumulation of lipids inside hepatocytes. Untreated NAFL can progress to non-alcoholic hepatitis (NASH), followed by fibrosis, cirrhosis, and hepatocellular carcinoma (HCC). The common denominator of the above-mentioned metabolic disorders seems to be insulin resistance, which occurs in NAFLD patients. Obesity is the greatest risk factor for lipid accumulation inside hepatocytes, but a part of the NAFLD patient population has a normal body weight according to the BMI index. Obese people with or without NAFLD have a higher incidence of small intestinal bacterial overgrowth (SIBO), and those suffering from NAFLD show increased intestinal permeability, including a more frequent presence of bacterial overgrowth in the small intestine (SIBO). The health consequences of SIBO are primarily malabsorption disorders (vitamin B12, iron, choline, fats, carbohydrates and proteins) and bile salt deconjugation. Undetected and untreated SIBO may lead to nutrient and/or energy malnutrition, thus directly impairing liver function (e.g., folic acid and choline deficiency). However, whether SIBO contributes to liver dysfunction, decreased intestinal barrier integrity, increased inflammation, endotoxemia and bacterial translocation is not yet clear. In this review, we focus on gut–liver axis and discuss critical points, novel insights and the role of nutrition, lifestyle, pre- and probiotics, medication and supplements in the therapy and prevention of both SIBO and NAFLD.

Baicalein alleviates non-alcoholic fatty liver disease in mice by ameliorating intestinal barrier dysfunction

Non-alcoholic fatty liver disease (NAFLD) is the main cause of chronic liver disease, and its pathological development is closely related to the gut-liver axis. The intestinal barrier, an important component of the gut-liver axis, can prevent gut microbes and endotoxins from entering the liver. Intestinal barrier function is impaired in patients with NAFLD. Baicalein, which is the main flavonoid in Scutellariae Radix, can improve NAFLD. However, whether baicalein alleviates NAFLD by ameliorating intestinal barrier dysfunction remains unclear. In this study, a methionine-choline deficient (MCD) diet-induced NAFLD mouse model is used. The effects of baicalein on lipid accumulation, inflammation and the intestinal barrier in MCD-fed mice were evaluated by detecting blood lipid levels, lipid accumulation, liver pathological changes, inflammatory factors, inflammatory signaling pathways, the three main short-chain fatty acids (acetate, propionate and butyrate), intestinal permeability and intestinal tight junction protein expression. Compared with the MCD-only group, baicalein intake decreased the serum and liver lipid levels. Moreover, the accumulation of lipid droplets and steatosis in the liver were also alleviated; all these results demonstrated that baicalein could alleviate NAFLD. Meanwhile, the levels of inflammatory cytokines decreased in the baicalein group. Further investigation of the mucosal permeability to 4 kDa fluorescein isothiocyanate-dextran, concentrations of short-chain fatty acids in feces, and the expression of intestinal zonula occluden 1 and claudin-1 indicated that a baicalein diet could decrease the intestinal permeability caused by a MCD diet. Moreover, the protein levels of p-NF-κB p65 and the ratio of p-NF-κB p65/NF-κB p65 increased, and IκB-α and PPARα decreased in NAFLD mice, while the administration of baicalein could alleviate these changes. The above results indicated that the mechanism of baicalein in the alleviation of NAFLD lies in the regulation of the intestinal barrier.

Impact of Sarcopenia on Non-Alcoholic Fatty Liver Disease

With the increasing incidence of non-alcoholic fatty liver disease (NAFLD) and the aging of the population, sarcopenia is attracting attention as one of the pathological conditions involved in the development and progression of NAFLD. In NAFLD, sarcopenia is closely associated with insulin resistance and results from the atrophy of skeletal muscle, an insulin target organ. In addition, inflammatory cytokines that promote skeletal muscle protein breakdown, low adiponectin levels leading to decreased insulin sensitivity, and hyperleptinemia are also involved in NAFLD pathogenesis. The presence of sarcopenia is a prognostic factor and increases the risk of mortality in patients with cirrhosis and post-treatment liver cancer. Sarcopenia, the presence of which mainly occurs due to decreased muscle mass, combined with increased visceral fat, can lead to sarcopenia-associated obesity, which increases the risk of NASH, liver fibrosis, and cardiovascular disease. In order to treat sarcopenia, it is necessary to properly evaluate sarcopenia status. Patients with high BMI, as in sarcopenic obesity, may improve with caloric restriction. However, inadequate oral intake may lead to further loss of muscle mass. Aerobic and resistance exercise should also be used appropriately.

AICAR Ameliorates Non-Alcoholic Fatty Liver Disease via Modulation of the HGF/NF-κB/SNARK Signaling Pathway and Restores Mitochondrial and Endoplasmic Reticular Impairments in High-Fat Diet-Fed Rats

Non-alcoholic fatty liver disease (NAFLD) is a global health problem characterized by altered lipid and redox homeostasis, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress. The AMP-dependent kinase (AMPK) agonist 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) has been shown to improve the outcome of NAFLD in the context of AMPK activation, yet the underlying molecular mechanism remains obscure. This study investigated the potential mechanism(s) of AICAR to attenuate NAFLD by exploring AICAR's effects on the HGF/NF-κB/SNARK axis and downstream effectors as well as mitochondrial and ER derangements. High-fat diet (HFD)-fed male Wistar rats were given intraperitoneal AICAR at 0.7 mg/g body weight or left untreated for 8 weeks. In vitro steatosis was also examined. ELISA, Western blotting, immunohistochemistry and RT-PCR were used to explore AICAR's effects. NAFLD was confirmed by steatosis score, dyslipidemia, altered glycemic, and redox status. HGF/NF-κB/SNARK was downregulated in HFD-fed rats receiving AICAR with improved hepatic steatosis and reduced inflammatory cytokines and oxidative stress. Aside from AMPK dominance, AICAR improved hepatic fatty acid oxidation and alleviated the ER stress response. In addition, it restored mitochondrial homeostasis by modulating Sirtuin 2 and mitochondrial quality gene expression. Our results provide a new mechanistic insight into the prophylactic role of AICAR in the prevention of NAFLD and its complications.

Elevated serum levels of diamine oxidase, D-lactate and lipopolysaccharides are associated with metabolic-associated fatty liver disease

BACKGROUND

Studies have suggested an association between metabolic-associated fatty liver disease (MAFLD) and intestinal barrier function. The present study aims to investigate the association between MAFLD and intestinal barrier impairment in humans and identify potential risk factors for MAFLD.

METHODS

A total of 491 patients were retrospectively enrolled in this study. The serum levels of diamine oxidase, D-lactate and lipopolysaccharide were measured to evaluate intestinal barrier integrity in patients with and without MAFLD. Binary logistic regression and correlational analyses were conducted to verify the association between MAFLD and serum levels of intestinal barrier biomarkers.

RESULTS

We enrolled 294 patients with MAFLD and 197 patients without MAFLD in this study. Patients with MAFLD had higher serum levels of diamine oxidase, D-lactate and lipopolysaccharide (P < 0.001) than those without MAFLD. Multivariate logistic regression analyses showed that BMI [odds ratio (OR) 1.324; P < 0.001], triglycerides (OR 2.649; P = 0.002), nonesterified fatty acids (OR 1.002; P = 0.011), diamine oxidase (OR 1.149; P = 0.011) and D-lactate (OR 1.221; P < 0.001) were independent risk factors for MAFLD. Additionally, serum levels of diamine oxidase and D-lactate increase as liver steatosis became more severe. MAFLD patients with ≥2 metabolic abnormalities had higher serum levels of lipopolysaccharide (P = 0.034).

CONCLUSIONS

MAFLD is associated with intestinal barrier impairment. Diamine oxidase and D-lactate are potential predictors of MAFLD, and their serum levels are related to liver steatosis. Intestinal barrier impairment is related to metabolic disorders in patients with MAFLD.

Pattern recognition receptors in the development of nonalcoholic fatty liver disease and progression to hepatocellular carcinoma: An emerging therapeutic strategy

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation and has become the leading chronic liver disease worldwide. NAFLD is viewed as the hepatic manifestation of metabolic syndrome, ranging from simple steatosis and nonalcoholic steatohepatitis (NASH) to advanced fibrosis, eventually leading to cirrhosis and hepatocellular carcinoma (HCC). The pathogenesis of NAFLD progression is still not clear. Pattern recognition receptor (PRR)-mediated innate immune responses play a critical role in the initiation of NAFLD and the progression of NAFLD-related HCC. Toll-like receptors (TLRs) and the cyclic GMP-AMP (cGAMP) synthase (cGAS) are the two major PRRs in hepatocytes and resident innate immune cells in the liver. Increasing evidence indicates that the overactivation of TLRs and the cGAS signaling pathways may contribute to the development of liver disorders, including NAFLD progression. However, induction of PRRs is critical for the release of type I interferons (IFN-I) and the maturation of dendritic cells (DCs), which prime systemic antitumor immunity in HCC therapy. In this review, we will summarize the emerging evidence regarding the molecular mechanisms of TLRs and cGAS in the development of NAFLD and HCC. The dysfunction of PRR-mediated innate immune response is a critical determinant of NAFLD pathology; targeting and selectively inhibiting TLRs and cGAS signaling provides therapeutic potential for treating NALF-associated diseases in humans.