Increased Liver Localization of Lipopolysaccharides in Human and Experimental NAFLD

Harnessing lactobacillus: a probiotic revolution in combating metabolic dysfunction-associated steatotic liver disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) involves fat buildup in the liver and is connected to a disruption in gut microbiota and a reduction in beneficial microbiota. Lactobacillus is an important probiotic that can grow in anaerobic or low-oxygen environment and is widely used in food industry and health fields. In recent years, the improvement of MASLD by Lactobacillus has been extensively studied. However, the detailed mechanisms by which different species of Lactobacillus improve MASLD have not been summarized. In this review, we present the potential of Lactobacillus as a non-drug approach to mitigate MASLD. We will discuss the preclinical and clinical research backing this method and the ways these probiotics improve MASLD. This review mainly presents the different species of Lactobacillus that improve MASLD, and various mechanisms by which Lactobacillus strains alleviate MASLD, including improving intestinal permeability and inflammation, reducing oxidative stress, and restoring of gut metabolites. Future research into mechanisms and larger clinical trials will help confirm the effectiveness of using Lactobacillus and related genera in the treatment of MASLD.

Unlocking the gut-liver axis: microbial contributions to the pathogenesis of metabolic-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a complex metabolic disorder characterized by hepatic lipid accumulation and subsequent inflammation. This condition is closely linked to metabolic syndrome and obesity, with its prevalence rising due to sedentary lifestyles and high-calorie diets. The pathogenesis of MAFLD involves multiple factors, including insulin resistance, lipotoxicity, oxidative stress, and inflammatory responses. The gut microbiota plays a crucial role in MAFLD development, with dysbiosis contributing to liver inflammation through various mechanisms, such as enhanced intestinal permeability and the translocation of bacterial products like lipopolysaccharide (LPS). Microbial metabolites, including short-chain fatty acids (SCFAs) and bile acids, influence hepatic function and immune responses, with potential implications for disease progression. Specific gut microbiome signatures have been identified in MAFLD patients, offering potential diagnostic and therapeutic targets. Moreover, gut-derived toxins, such as endotoxins, lipopolysaccharides, trimethylamine-N-oxide and bacterial metabolites, significantly influence liver damage and inflammation, highlighting the complex interplay between the gut microbiome and hepatic health. This review comprehensively examines the complex interplay between the gut microbiota and MAFLD, focusing on underlying pathogenic mechanisms, potential biomarkers, and emerging microbiome-targeted therapeutic strategies for disease management.

A host enzyme reduces metabolic dysfunction-associated steatotic liver disease (MASLD) by inactivating intestinal lipopolysaccharide

The incidence of metabolic dysfunction-associated steatotic liver disease (MASLD) has been increasing worldwide. Since gut-derived bacterial lipopolysaccharides (LPS) can travel via the portal vein to the liver and play an important role in producing hepatic pathology, it seemed possible that (1) LPS stimulates hepatic cells to accumulate lipid, and (2) inactivating LPS can be preventive. Acyloxyacyl hydrolase (AOAH), the eukaryotic lipase that inactivates LPS and oxidized phospholipids, is produced in the intestine, liver, and other organs. We fed mice either normal chow or a high-fat diet for 28 weeks and found that Aoah-/- mice accumulated more hepatic lipid than did Aoah+/+ mice. In young mice, before increased hepatic fat accumulation was observed, Aoah-/- mouse livers increased their abundance of sterol regulatory element-binding protein 1, and the expression of its target genes that promote fatty acid synthesis. Aoah-/- mice also increased hepatic expression of Cd36 and Fabp3, which mediate fatty acid uptake, and decreased expression of fatty acid-oxidation-related genes Acot2 and Ppara. Our results provide evidence that increasing AOAH abundance in the gut, bloodstream, and/or liver may be an effective strategy for preventing or treating MASLD.

Butyrate Regulates Intestinal DNA Virome and Lipopolysaccharide Levels to Prevent High-Fat Diet-Related Liver Damage in Rats

As the adsorption receptor of bacteriophage tail protein, bacterial lipopolysaccharide (LPS) is a main culprit responsible for nonalcoholic fatty liver disease (NAFLD) caused by high-fat diets. However, few studies have focused on how the interaction between intestinal bacteriophages and bacterial LPS affects the development and progression of NAFLD. Herein, we determined that excessive fat intake significantly increases the levels of endogenous LPS, while the administration of beneficial metabolites of the intestinal microbiota (specifically butyrate) alleviated hepatic injury in rats. The beneficial mechanism of butyrate was attributed to the reprogramming of the structure of the intestinal DNA virome (primarily, phageome). Butyrate possesses the potential to augment bacteriophagic microbial diversity, thereby potentially facilitating interactions between intestinal bacteriophages and bacterial LPS (in the case of homologous phage), further improving mitochondrial dysfunction and reactive oxygen species production, which, in turn, lowered HepG2 cell damage. Likewise, fecal phage transplantation further confirmed that intestinal phages from rats that received butyrate could effectively interact with bacterial LPS to reduce liver damage in rats. Taken together, modifying the intestinal phageome is a promising treatment option for high-fat diet-related NAFLD.

Metabolic dysfunction-associated steatotic liver disease and the gut microbiome: pathogenic insights and therapeutic innovations

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a major cause of liver disease worldwide, and our understanding of its pathogenesis continues to evolve. MASLD progresses from steatosis to steatohepatitis, fibrosis, and cirrhosis, and this Review explores how the gut microbiome and their metabolites contribute to MASLD pathogenesis. We explore the complexity and importance of the intestinal barrier function and how disruptions of the intestinal barrier and dysbiosis work in concert to promote the onset and progression of MASLD. The Review focuses on specific bacterial, viral, and fungal communities that impact the trajectory of MASLD and how specific metabolites (including ethanol, bile acids, short chain fatty acids, and other metabolites) contribute to disease pathogenesis. Finally, we underscore how knowledge of the interaction between gut microbes and the intestinal barrier may be leveraged for MASLD microbial-based therapeutics. Here, we include a discussion of the therapeutic potential of prebiotics, probiotics, postbiotics, and microbial-derived metabolites.

Mitochondria at the Crossroads: Linking the Mediterranean Diet to Metabolic Health and Non-Pharmacological Approaches to NAFLD

Nonalcoholic fatty liver disease (NAFLD) is a growing global health concern that is closely linked to metabolic syndrome, yet no approved pharmacological treatment exists. The Mediterranean diet (MD) emerged as a first-line dietary intervention for NAFLD, offering metabolic and hepatoprotective benefits. Now conceptualized as a complex chemical matrix rich in bioactive compounds, the MD exerts antioxidant and anti-inflammatory effects, improving insulin sensitivity and lipid metabolism. Mitochondria play a central role in NAFLD pathophysiology, influencing energy metabolism, oxidative stress, and lipid homeostasis. Emerging evidence suggests that the MD's bioactive compounds enhance mitochondrial function by modulating oxidative phosphorylation, biogenesis, and mitophagy. However, most research has focused on individual compounds rather than the MD as a whole, leaving gaps in understanding its collective impact as a complex dietary pattern. This narrative review explores how the MD and its bioactive compounds influence mitochondrial health in NAFLD, highlighting key pathways such as mitochondrial substrate control, dynamics, and energy efficiency. A literature search was conducted to identify relevant studies on the MD, mitochondria, and NAFLD. While the search was promising, our understanding remains incomplete, particularly when current knowledge is limited by the lack of mechanistic and comprehensive studies on the MD's holistic impact. Future research integrating cutting-edge experimental approaches is needed to elucidate the intricate diet-mitochondria interactions. A deeper understanding of how the MD influences mitochondrial health in NAFLD is essential for developing precision-targeted nutritional strategies that can effectively prevent and manage the disease.

Polysaccharides Extracted from Old Stalks of Asparagus officinalis L. Improve Nonalcoholic Fatty Liver by Increasing the Gut Butyric Acid Content and Improving Gut Barrier Function

Nonalcoholic fatty liver disease (NAFLD) ranks among the most prevalent chronic liver diseases worldwide, yet effective treatments remain scarce. Old stalks of Asparagus officinalis L. are rich in polysaccharides. The anti-NAFLD mechanism of polysaccharides from old stalks of A. officinalis (AP) requires further study. Here, we studied the effects of AP on NAFLD mice and its impact on the gut microbiota. AP intervention reduces blood lipids and liver lipids and reduces liver injury and inflammation in mice with NAFLD. Moreover, AP intervention changed gut microbiota composition and increased the abundances of butyric acid-producing bacteria, thereby increasing plasma concentration of butyric acid. Furthermore, AP intervention regulated the AMPK/SREBPs signaling pathway, thereby affecting hepatic lipid synthesis. Additionally, AP intervention improved gut barrier function and reduced plasma LPS levels, which subsequently inhibited the LPS/TLR4/NF-κB signaling pathway, thereby alleviating inflammation in NAFLD model mice. Importantly, fecal microbiota transplant (FMT) outcomes demonstrated that AP-induced changes in the gut microbiota impact the AMPK/SREBPs and LPS/TLR4/NF-κB pathways. These data suggest that AP intervention ameliorates NAFLD by regulating the gut microbiota. These research provides a scientific foundation for the use of the stalks of A. officinalis in the treatment of NAFLD.

Ta4C3 MXene Slows Progression of Fatty Liver Disease through Its Anti-Inflammatory and ROS-Scavenging Effects

Treating metabolic dysfunction-associated fatty liver disease (MAFLD) and reducing the occurrence of MAFLD-associated liver cancer remain challenging. Two-dimensional (2D) tantalum carbide (Ta4C3) MXene nanozymes (MXenzymes) exhibit antioxidant and anti-inflammatory activities and have thus attracted considerable attention in the fields of oncology and engineering. However, the potential mechanism of action and bioactive properties of Ta4C3 in MAFLD remain uncertain. In our study, Ta4C3 not only inhibited lipid accumulation and disrupted lipid metabolism in hepatocytes but also reduced cell death caused by fatty acids by decreasing intracellular reactive oxygen species (ROS) levels, which significantly promoted the polarization of M1 macrophages to M2 macrophages by alleviating oxidative stress and further suppressing inflammatory factor expression. In mice fed a methionine-choline-deficient (MCD) diet, Ta4C3 reduced lipid accumulation, the infiltration of inflammatory cells, and liver cell apoptosis by modulating the cellular microenvironment through its anti-inflammatory and antioxidant properties. Therefore, Ta4C3 can be used as a multifunctional bioactive material to alleviate hepatic steatosis and inflammation in individuals with MAFLD/metabolic dysfunction-associated steatohepatitis (MASH) because of its robust antioxidant and anti-inflammatory effects.

Grape pomace extract attenuates high fat diet-induced endotoxemia and liver steatosis in mice

Obesity is a prominent global health concern associated with chronic inflammation and metabolic disorders, such as insulin resistance, type 2 diabetes, and non-alcoholic fatty liver disease (NAFLD). Excessive consumption of saturated fats exacerbates these conditions by increasing intestinal barrier permeability and circulating endotoxins. This study aims to investigate, in a murine model of high-fat diet (HFD)-induced obesity, the potential beneficial effects of a grape pomace extract (GPE), rich in phenolic compounds, at mitigating endotoxemia, and liver steatosis. Underlying mechanisms were characterized in an in vitro model of intestinal inflammation and permeabilization, as induced by tumor necrosis factor alpha (TNFα) in Caco-2 cell monolayers. Consumption of a HFD (60% calories from fat) for 13 weeks induced obesity, insulin resistance, and liver damage, evidenced by higher levels of plasma alanine aminotransferase (ALT), hepatic triglycerides content, and steatosis. In addition, HFD caused metabolic endotoxemia, hepatic toll-like receptor 4 (TLR4) upregulation and inflammation. GPE supplementation significantly reduced body weight and subcutaneous and visceral adipose tissue weight, and attenuated metabolic dysregulation. Furthermore, GPE decreased circulating LPS levels and mitigated HFD-mediated hepatic TLR4 upregulation, nuclear factor kappa B (NF-κB) activation, and downstream expression of proteins involved in oxidative stress and inflammation (NOX4, TNFα, and F4/80). In Caco-2 cells, GPE mitigated TNFα-induced monolayer permeabilization, decreased tight junction (TJ) protein levels, enhanced cellular oxidant production, activated redox-sensitive signaling, i.e., NF-κB and ERK1/2, and increased NOX1 and MLCK mRNA levels, the latter being a key regulator of monolayer permeability. The above findings suggest that GPE may protect against HFD-induced obesity and associated metabolic dysfunction (insulin resistance and NAFLD) by modulating intestinal barrier integrity and related endotoxemia.

Recipient toll-like receptor 4 determines the outcome of ischemia-reperfusion injury in steatotic liver transplantation in mice

Toll-like receptor 4 (TLR4) plays a crucial role in ischemia-reperfusion injury (IRI) after liver transplantation (LT). However, the role of TLR4 in the context of steatotic grafts remains unclear. In this study, we developed a mouse model to explore IRI mechanisms in steatotic LT using TLR4 knockout mice as recipients. We successfully transplanted steatotic grafts with approximately 35% macrosteatosis and 5 hours of cold storage. Compared to normal LT, steatotic LT resulted in significantly higher serum level of alanine aminotransferase and high mobility group box 1 (HMGB1), higher transcriptional expression of inflammatory markers (C-X-C motif chemokine ligand 2, caspase-1, and caspase-11), and increased infiltration of CD11b-positive cells, correlating with lower survival. Serum HMGB1 and cleaved caspase-3 activation peaked earlier than serum alanine aminotransferase, with cold-stored steatotic grafts releasing more HMGB1. Notably, TLR4 knockout recipients demonstrated improved survival, attenuated inflammatory response, and reduced apoptosis. These findings suggest that TLR4 deficiency in recipients ameliorates IRI in steatotic LT, highlighting the importance of recipient immune modulation in mitigating steatotic graft injury.

The potential roles of gut microbiome in porto-sinusoidal vascular disease: an under-researched crossroad

Accumulating evidence indicates that patients with liver diseases exhibit distinct microbiological profiles, which can be attributed to the bidirectional relationship of the gut-liver axis. Porto-sinusoidal vascular disease (PSVD) has recently been introduced to describe a group of vascular diseases of the liver, involving the portal venules and sinusoids. Although the pathophysiology of PSVD is not yet fully understood, several predisposing conditions, including immunodeficiency, inflammatory bowel disease, abdominal bacterial infections are associated with the increasing in intestinal permeability and microbial translocation, supporting the role of altered gut microbiota and gut-derived endotoxins in PSVD etiopathogenesis. Recent studies have proposed that the gut microbiome may play a crucial role in the pathophysiology of intrahepatic vascular lesions, potentially influencing the onset and progression of PSVD in this context. This review aims to summarize the current understanding of the gut microbiome's potential role in the pathogenesis of hepatic microvascular abnormalities and thrombosis, and to briefly describe their interactions with PSVD. The insights into gut microbiota and their potential influence on the onset and progression of PSVD may pave the way for new diagnostic, prognostic, and therapeutic strategies.

Early-life antibiotic exposure aggravates hepatic steatosis through enhanced endotoxemia and lipotoxic effects driven by gut Parabacteroides

Compelling evidence supports a link between early-life gut microbiota and the metabolic outcomes in later life. Using an early-life antibiotic exposure model in BALB/c mice, we investigated the life-course impact of prenatal and/or postnatal antibiotic exposures on the gut microbiome of offspring and the development of metabolic dysfunction-associated steatotic liver disease (MASLD). Compared to prenatal antibiotic exposure alone, postnatal antibiotic exposure more profoundly affected gut microbiota development and succession, which led to aggravated endotoxemia and metabolic dysfunctions. This was primarily resulted from the overblooming of gut Parabacteroides and hepatic accumulation of cytotoxic lysophosphatidyl cholines (LPCs), which acted in conjunction with LPS derived from Parabacteroides distasonis (LPS_PA) to induce cholesterol metabolic dysregulations, endoplasmic reticulum (ER) stress and apoptosis. Integrated serum metabolomics, hepatic lipidomics and transcriptomics revealed enhanced glycerophospholipid hydrolysis and LPC production in association with the upregulation of PLA2G10, the gene controlling the expression of the group X secretory Phospholipase A2s (sPLA2-X). Taken together, our results show microbial modulations on the systemic MASLD pathogenesis and hepatocellular lipotoxicity pathways following early-life antibiotic exposure, hence help inform refined clinical practices to avoid any prolonged maternal antibiotic administration in early life and potential gut microbiota-targeted intervention strategies.

Dark chocolate's impact on low-grade endotoxemia in metabolic dysfunction-associated steatohepatitis

BACKGROUND AND AIMS

Cocoa may have prebiotic effects and improve gut barrier function. However, it remains unclear whether dark chocolate can reduce lipopolysaccharide (LPS) levels in patients with metabolic dysfunction-associated steatohepatitis (MASH). This study aims to evaluate the effect of dark chocolate compared to milk chocolate on endotoxemia in patients with MASH.

METHODS AND RESULTS

Nineteen patients with MASH were randomly assigned in a crossover design to consume either 40 g/d of dark chocolate (>85% cocoa) or 40 g/d of milk chocolate (<35% cocoa) for 2 weeks to evaluate circulating levels of LPS and zonulin. A significant difference between treatments was observed in LPS (P = 0.04) and zonulin (P = 0.02) levels based on the ANOVA conducted on the crossover study data. Pairwise comparisons revealed that, compared to baseline, after 14 days of dark chocolate consumption, LPS levels decreased from 22 ± 4 to 19 ± 4 pg/dL (-15%), and zonulin levels decreased from 3.2 ± 0.9 to 2.5 ± 0.8 pg/mL (-20%). Linear correlation analysis indicated that the change (Δ) in LPS values before and after chocolate intake correlated with the change (Δ) in zonulin levels (R = 0.340, P = 0.03).

CONCLUSIONS

This study demonstrates that dark chocolate reduces circulating levels of LPS and zonulin in patients with MASH.

Macronutrient Modulation in Metabolic Dysfunction-Associated Steatotic Liver Disease-the Molecular Role of Fatty Acids compared with Sugars in Human Metabolism and Disease Progression

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a significant public health concern, with its progression to metabolic dysfunction-associated steatohepatitis (MASH) and fibrosis leading to severe outcomes including cirrhosis, hepatocellular carcinoma, and liver failure. Whereas obesity and excess energy intake are well-established contributors to the development and progression of MASLD, the distinct role of specific macronutrients is less clear. This review examines the mechanistic pathways through which dietary fatty acids and sugars contribute to the development of hepatic inflammation and fibrosis, offering a nuanced understanding of their respective roles in MASLD progression. In terms of addressing potential therapeutic options, human intervention studies that investigate whether modifying the intake of dietary fats and carbohydrates affects MASLD progression are reviewed. By integrating this evidence, this review seeks to bridge the gap in the understanding between the mechanisms of macronutrient-driven MASLD progression and the effect of altering the intake of these nutrients in the clinical setting and presents a foundation for future research into targeted dietary strategies for the treatment of the disease.

Drug Pipeline for MASLD: What Can Be Learned from the Successful Story of Resmetirom

Metabolic dysfunction-associated steatotic liver disease (MASLD) and its progressive form, metabolic dysfunction-associated steatohepatitis (MASH), represent a growing global health problem linked to obesity, insulin resistance, and dyslipidemia. MASLD often leads to fibrosis, cirrhosis, and hepatocellular carcinoma. Currently, therapeutic options are limited, emphasizing the need for novel, targeted pharmacological interventions. Resmetirom, a selective thyroid hormone receptor beta (THR-β) agonist, offers a promising approach by specifically enhancing hepatic metabolism while minimizing systemic effects. Clinical trials have demonstrated its capacity to reduce hepatic triglyceride accumulation and improve lipid profiles. Early- and advanced-phase studies, including the MAESTRO program, highlight significant reductions in hepatic fat content and favorable impacts on noninvasive biomarkers of fibrosis with minimal side effects. This review highlights evidence from pivotal studies, explores resmetirom's mechanism of action, and compares its efficacy and safety with other emerging therapeutic agents. While resmetirom marks a breakthrough in non-cirrhotic MASH management, further long-term studies are essential to fully evaluate its clinical benefits and potential regulatory approval for broader use in MASLD and MASH.

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.

Liver diseases: epidemiology, causes, trends and predictions

As a highly complex organ with digestive, endocrine, and immune-regulatory functions, the liver is pivotal in maintaining physiological homeostasis through its roles in metabolism, detoxification, and immune response. Various factors including viruses, alcohol, metabolites, toxins, and other pathogenic agents can compromise liver function, leading to acute or chronic injury that may progress to end-stage liver diseases. While sharing common features, liver diseases exhibit distinct pathophysiological, clinical, and therapeutic profiles. Currently, liver diseases contribute to approximately 2 million deaths globally each year, imposing significant economic and social burdens worldwide. However, there is no cure for many kinds of liver diseases, partly due to a lack of thorough understanding of the development of these liver diseases. Therefore, this review provides a comprehensive examination of the epidemiology and characteristics of liver diseases, covering a spectrum from acute and chronic conditions to end-stage manifestations. We also highlight the multifaceted mechanisms underlying the initiation and progression of liver diseases, spanning molecular and cellular levels to organ networks. Additionally, this review offers updates on innovative diagnostic techniques, current treatments, and potential therapeutic targets presently under clinical evaluation. Recent advances in understanding the pathogenesis of liver diseases hold critical implications and translational value for the development of novel therapeutic strategies.

Microenvironmental determinants of endothelial cell heterogeneity

During development, endothelial cells (ECs) undergo an extraordinary specialization by which generic capillary microcirculatory networks spanning from arteries to veins transform into patterned organotypic zonated blood vessels. These capillary ECs become specialized to support the cellular and metabolic demands of each specific organ, including supplying tissue-specific angiocrine factors that orchestrate organ development, maintenance of organ-specific functions and regeneration of injured adult organs. Here, we illustrate the mechanisms by which microenvironmental signals emanating from non-vascular niche cells induce generic ECs to acquire specific inter-organ and intra-organ functional attributes. We describe how perivascular, parenchymal and immune cells dictate vascular heterogeneity and capillary zonation, and how this system is maintained through tissue-specific signalling activated by vasculogenic and angiogenic factors and deposition of matrix components. We also discuss how perturbation of organotypic vascular niche cues lead to erasure of EC signatures, contributing to the pathogenesis of disease processes. We also describe approaches that use reconstitution of tissue-specific signatures of ECs to promote regeneration of damaged organs.

Qinggan Yipi capsule ameliorates hepatic fibrosis in rats by down-regulating the TGF-β1/Smad2/3 signaling pathway and improving gut microbiota imbalance

Background and objective

Qinggan Yipi Capsule (QgYp) is a hospital preparation that has been used for many years in the treatment of chronic liver diseases. However, the mechanism of QgYp in ameliorating hepatic fibrosis (HF) remains unclear. This study aims to clarify the anti-liver fibrosis effect of QgYp and its mechanism of action.

Methods

This study uses a carbon tetrachloride (CCl4) induced HF rat model and TGF-β1 stimulated HSC-T6 cell line (rat HSCs) as experimental models. The therapeutic effects were evaluated through pathology, biochemical tests, and ELISA. The therapeutic mechanism of QgYp for HF was predicted through network pharmacology. The expression of TGF-β1/Smad2/3 related proteins was detected by qPCR analysis and Western blot analysis. The composition of the gut microbiota was analyzed using 16S rRNA gene sequencing.

Results

Histopathological analysis, serum biochemical tests, and ELISA measurements showed that QgYp effectively decreased the levels of ALT, AST, HA, LN, PCIII, and IV-C while improving collagen deposition and hepatocyte necrosis. Protein-protein interaction (PPI) network analysis screened HF-related genes, including peroxisome proliferator-activated receptor gamma (PPARG), tumor necrosis factor (TNF), and TGF-β1. GO and KEGG analyses indicated that QgYp significantly affects TGF-β signaling pathway. In addition, the results of qPCR and Western blot analysis from both in vitro and in vivo experiments indicated that QgYp significantly downregulated the expression of proteins and mRNA associated with the TGF-β1/Smad2/3 pathway. The 16S rDNA gene sequencing results showed that QgYp can increase the diversity and richness of the gut microbiota in HF rats and alter the composition of the gut microbiota.

Conclusion

QgYp could effectively ameliorate HF, and this effect might be connected to the downregulation of the TGF-β1/Smad2/3 pathway, the suppression of HSCs activation, and regulation of gut microbiota dysbiosis.

Intestinal Akkermansia muciniphila complements the efficacy of PD1 therapy in MAFLD-related hepatocellular carcinoma

Immune checkpoint inhibitors are not effective for metabolic dysfunction-associated fatty liver disease (MAFLD)-hepatocellular carcinoma (HCC) patients, and identifying the key gut microbiota that contributes to immune resistance in these patients is crucial. Analysis using 16S rRNA sequencing reveals a decrease in Akkermansia muciniphila (Akk) during MAFLD-promoted HCC development. Administration of Akk ameliorates liver steatosis and effectively attenuates the tumor growth in orthotopic MAFLD-HCC mouse models. Akk repairs the intestinal lining, with a decrease in the serum lipopolysaccharide (LPS) and bile acid metabolites, along with decrease in the populations of monocytic myeloid-derived suppressor cells (m-MDSCs) and M2 macrophages. Akk in combination with PD1 treatment exerts maximal growth-suppressive effect in multiple MAFLD-HCC mouse models with increased infiltration and activation of T cells. Clinically, low Akk levels are correlated with PD1 resistance and poor progression-free survival. In conclusion, Akk is involved in the immune resistance of MAFLD-HCC and serves as a predictive biomarker for PD1 response in HCC.

Nicotinamide Adenine Dinucleotide Phosphate Oxidases and Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by lipid accumulation in the liver due to an excess in their supplies or an impairment in their management. While some patients remain stable for years, a proportion of them progress up to steatohepatitis (MASH). MASLD links with systemic pathways being associated with metabolic and non-metabolic diseases. Although liver lipid accumulation represents the first hit for MASLD, the pathophysiology of its development and progression to MASH remains not completely understood. Oxidative stress has received particular attention in recent years, as most of the oxidative process occurs in the liver, which is also the target of oxidative stress-induced damage. Growing evidence linked the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOX) to the increased liver production of reactive oxygen species up to liver damage and fibrosis. NOX acts both in hepatocytes and in non-parenchymal hepatic cells, contributing to hepatocyte lipotoxicity, impaired hepatic microcirculation, hepatic stellate, and mesenchymal stem cells activation and proliferation. This review aims to summarize the current knowledge on the involvement of oxidative stress in the MASLD-MASH transition, focusing on the role of NOX isoforms, and to suggest targeting NOX as a therapeutic approach in MASLD.

Randomised double-blind placebo-controlled trial protocol to evaluate the therapeutic efficacy of lyophilised faecal microbiota capsules amended with next-generation beneficial bacteria in individuals with metabolic dysfunction-associated steatohepatitis

BACKGROUND

The spectrum of metabolic dysfunction-associated steatotic liver disease (MASLD) is highly prevalent, affecting 30% of the world's population, with a significant risk of hepatic and cardiometabolic complications. Different stages of MASLD are accompanied by distinct gut microbial profiles, and several microbial components have been implicated in MASLD pathophysiology. Indeed, earlier studies demonstrated that hepatic necroinflammation was reduced in individuals with MASLD after allogenic faecal microbiota transplantation (FMT) from healthy donors on a vegan diet. Here, we further investigate the therapeutic potential of gut microbiome modulation using a syntrophic combination of next-generation beneficial bacteria with FMT in individuals with advanced MASLD.

METHODS AND ANALYSIS

This trial is a randomised, double-blind, placebo-controlled study investigating the therapeutic potential of lyophilised faecal microbiota capsules (LFMCs) in individuals with metabolic dysfunction-associated steatohepatitis. In this study, 48 participants will be randomised 1:1 to receive either healthy vegan donor LFMCs or placebo for 24 weeks. In addition, all participants will be supplemented with a set of next-generation beneficial bacteria, including Anaerobutyricum soehngenii, pasteurised Akkermansia muciniphila and Bifidobacterium animalis subsp. lactis, as well as fructo-oligosaccharides. A liver biopsy will be performed at baseline and at the end of the trial. In addition, participants will be assessed through MRI, FibroScan, blood tests, faecal samples and continuous glucose monitoring. The first participant was enrolled on 25 April 2023.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Medical Ethics Committee of the University Medical Centre of Amsterdam. The results of this study will be disseminated through peer-reviewed journals.

TRIAL REGISTRATION NUMBER

The trial is registered on clinicaltrials.gov (NCT05821010).

The role of intestinal flora in metabolic dysfunction-associated steatotic liver disease and treatment strategies

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a common multi-factorial liver disease, and its incidence is gradually increasing worldwide. Many reports have revealed that intestinal flora plays a crucial role for the occurrence and development of MASLD, through mechanisms such as flora translocation, endogenous ethanol production, dysregulation of choline metabolism and bile acid, and endotoxemia. Here, we review the relationship between intestinal flora and MASLD, as well as interventions for MASLD, such as prebiotics, probiotics, synbiotics, and intestinal flora transplantation. Intervention strategies targeting the intestinal flora along with its metabolites may be new targets for preventing and treating MASLD.

Gut Microbiota at the Crossroad of Hepatic Oxidative Stress and MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent chronic liver condition marked by excessive lipid accumulation in hepatic tissue. This disorder can lead to a range of pathological outcomes, including metabolic dysfunction-associated steatohepatitis (MASH) and cirrhosis. Despite extensive research, the molecular mechanisms driving MASLD initiation and progression remain incompletely understood. Oxidative stress and lipid peroxidation are pivotal in the "multiple parallel hit model", contributing to hepatic cell death and tissue damage. Gut microbiota plays a substantial role in modulating hepatic oxidative stress through multiple pathways: impairing the intestinal barrier, which results in bacterial translocation and chronic hepatic inflammation; modifying bile acid structure, which impacts signaling cascades involved in lipidic metabolism; influencing hepatocytes' ferroptosis, a form of programmed cell death; regulating trimethylamine N-oxide (TMAO) metabolism; and activating platelet function, both recently identified as pathogenetic factors in MASH progression. Moreover, various exogenous factors impact gut microbiota and its involvement in MASLD-related oxidative stress, such as air pollution, physical activity, cigarette smoke, alcohol, and dietary patterns. This manuscript aims to provide a state-of-the-art overview focused on the intricate interplay between gut microbiota, lipid peroxidation, and MASLD pathogenesis, offering insights into potential strategies to prevent disease progression and its associated complications.

Interplay among IL1R1, gut microbiota, and bile acids in metabolic dysfunction-associated steatotic liver disease: a comprehensive review

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent metabolic disorder characterized by hepatic steatosis associated with metabolic abnormalities. Recent research has shed light on the intricate interplay among interleukin-1 receptor 1 (IL1R1), gut microbiota, and bile acids in the pathogenesis of MASLD. This review aims to provide a comprehensive overview of the current understanding of the role of IL1R1, gut microbiota, and bile acids in MASLD, exploring their interrelationships and potential mechanisms. We summarize the evidence supporting the involvement of IL1R1 in inflammation, discuss the influence of gut microbiota on bile acid metabolism and its influence on liver health, and elucidate the bidirectional interactions among IL1R1 signaling, gut microbiota composition, and bile acid homeostasis in MASLD. Furthermore, we highlight emerging therapeutic strategies targeting these interrelated pathways for the management of MASLD.

Lactobacillus sp. for the Attenuation of Metabolic Dysfunction-Associated Steatotic Liver Disease in Mice

Probiotics are studied for their therapeutic potential in the treatment of several diseases, including metabolic dysfunction-associated steatotic liver disease (MASLD). Part of the significant progress made in understanding the pathogenesis of steatosis has come from identifying the complex interplay between the gut microbiome and liver function. Recently, probiotics have shown beneficial effects for the treatment and prevention of steatosis and MASLD in rodent models and in clinical trials. Numerous studies have demonstrated the promising potential of lactic acid bacteria, especially the genus Lactobacillus. Lactobacillus is a prominent bile acid hydrolase bacterium that is involved in the biotransformation of bile acids. This genus' modulation of the gut microbiota also contributes to overall gut health; it controls gut microbial overgrowth, shapes the intestinal bile acid pool, and alleviates inflammation. This narrative review offers a comprehensive summary of the potential of Lactobacillus in the gut-liver axis to attenuate steatosis and MASLD. It also highlights the roles of Lactobacillus in hepatic lipid metabolism, insulin resistance, inflammation and fibrosis, and bile acid synthesis in attenuating MASLD.

MetALD: Does it require a different therapeutic option?

New guidelines for the definitions of steatotic liver disease have named the entity of metabolic dysfunction and alcohol-associated liver disease (MetALD) as an overlap condition of metabolic dysfunction-associated steatotic liver disease (MASLD) and alcohol-associated liver disease. There is a broad range of therapeutics in all stages of development for MASLD, but these therapeutics, in general, have not been studied in patients with significant ongoing alcohol use. In this review, we discuss the current understanding of the endogenous and exogenous risks for MASLD and MetALD. Rational strategies for therapeutic intervention in MetALD include biopsychosocial interventions, alcohol use cessation strategies, including the use of medications for alcohol use disorder, and judicious use of therapeutics for steatotic liver disease. Therapeutics with promise for MetALD include incretin-based therapies, FGF21 agonists, thyroid hormone receptor beta agonists, sodium-glucose co-transporter 2 inhibitors, and agents to modify de novo lipogenesis. Currently, glucagon-like peptide 1 receptor agonists and peroxisome proliferator-activated receptor γ agonists have the largest body of literature supporting their use in MASLD, and there is a paucity of agents in trials for alcohol-associated liver disease. From existing studies, it is not clear if unique therapeutics or a combinatorial approach are needed for MetALD. Further elucidation of the safety and benefits of MASLD-related therapies is of paramount importance for advancing therapeutics for MetALD in carefully designed inclusive clinical trials.

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.

Prebiotics targeting gut-liver axis to treat non-alcoholic fatty liver disease

Non-alcoholic steatohepatitis (NASH) is a high-prevalence, rapidly growing form of non-alcoholic fatty liver disease (NAFLD), which is closely linked to obesity and metabolic disorders. Gut microbiota has been increasingly recognized as a key factor in the onset of NAFLD in recent years. The liver can be strongly influenced by changes in the gut microbiota through the portal vein, giving the gut-liver axis a very important role in understanding the pathophysiology of liver diseases. A healthy intestinal barrier is characterized by selective permeability to nutrients, metabolites, water and bacterial products and its impairment may be a predisposing or aggravating condition for the progression of NAFLD. In most cases, NAFLD patients follow a Western diet pattern, which is closely linked to obesity and associated metabolic diseases, promoting inflammation, structural and behavioral changes in the gut microbiota. In fact, factors such as age, gender, genetic or environmental factors may induce a dysbiotic microbiota that promotes epithelial barrier dysfunction and increased intestinal permeability, favoring the progression of NAFLD. In this context, new dietary approaches, such as prebiotics, are emerging to prevent disease and maintain health. In this review, we reported the role of the gut-liver axis in the pathogenesis of NAFLD and investigated the potential therapeutic effect of prebiotics on the enhancement of intestinal barrier dysfunction, hepatic steatosis and, consequently, the progression of NAFLD.

Rifaximin alleviates MCD diet-induced NASH in mice by restoring the gut microbiota and intestinal barrier

AIMS

Due to the increasing global incidence rate of nonalcoholic steatohepatitis (NASH) combined with the lack of effective treatment methods for this disease, there is an urgent need to find new treatment strategies. The aim of this study was to investigate the efficacy of rifaximin in preventing and treating NASH and the related mechanism.

MATERIALS AND METHODS

A NASH model was constructed by feeding male C57BL/6 mice a methionine-choline-deficient (MCD) diet for 4 weeks. Rifaximin was administered for 1 week before MCD diet feeding or during the last week of MCD diet feeding to investigate its preventive or therapeutic effects. Liver pathology, hepatic enzyme levels and metabolic indices were measured to evaluate the effects of rifaximin on NASH. Intestinal barrier integrity was measured via the Ussing chamber system and western blotting. 16S rDNA sequencing was conducted to investigate the fecal microbiota composition. Western blotting was performed to evaluate peroxisome proliferator activated receptor (PPAR)α and PPARγ protein levels.

KEY FINDINGS

Rifaximin effectively alleviated MCD diet-induced NASH. The microbiota composition in MCD diet-fed mice was significantly altered, and intestinal barrier integrity was disrupted. Dysbiosis and intestinal barrier dysfunction were reversed by rifaximin. In addition, rifaximin modulated PPARα and PPARγ expression in the liver.

SIGNIFICANCE

Rifaximin effectively alleviated MCD diet-induced NASH by restoring the gut microbiota and reversing intestinal barrier dysfunction, suggesting that rifaximin treatment is a new approach for preventing and treating NASH.

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.

Co-exposure to different bacterial species' lipopolysaccharides with the NASH diet exacerbates NASH and liver fibrosis progression in mice

BACKGROUND AND AIM

With the obesity epidemic, nonalcoholic fatty liver disease (NAFLD) has become a public health concern, but its progression mechanism remains unclear. Experimental models mimicking human NAFLD/steatohepatitis (NASH) are crucial. This study simulates gut microbiota imbalance effects on NASH and liver fibrosis.

METHODS

We used different bacterial sources of lipopolysaccharide (LPS), including Escherichia coli (GEC) and Salmonella abortus equi (GSE), combined with a Gubra Amylin NASH (GAN) diet to induce NASH and liver fibrosis.

RESULTS

The GSE group showed significantly higher serum alanine aminotransferase, hydroxyproline, CD68-positive cells, α-smooth muscle actin, glial fibrillary acidic protein, and TNF-α, COL1A1, TGF-β, and NLRP3 expressions compared to the the GAN group. The GSE group also had higher Erysipelotrichaceae, Akkermansiaceae, and Bacteroidaceae family numbers.

CONCLUSIONS

The GAN diet with LPS treatment successfully induced NASH and fibrosis making this model useful for preclinical NASH drug testing.

Understanding Why Metabolic-Dysfunction-Associated Steatohepatitis Lags Behind Hepatitis C in Therapeutic Development and Treatment Advances

Therapeutic development for metabolic-dysfunction-associated steatohepatitis (MASH) trails behind the success seen in hepatitis C virus (HCV) management. HCV, characterized by a viral etiology, benefits from direct-acting antivirals (DAAs) targeting viral proteins, achieving cure rates exceeding 90%. In contrast, MASH involves complex metabolic, genetic, and environmental factors, presenting challenges for drug development. Non-invasive diagnostics like ultrasound, FibroScan, and serum biomarkers, while increasingly used, lack the diagnostic accuracy of liver biopsy, the current gold standard. This review evaluates therapies for MASH, including resmetirom (Rezdiffra) and combinations like pioglitazone and vitamin E, which show potential but offer modest improvements due to MASH’s heterogeneity. The limited efficacy of these treatments highlights the need for multi-targeted strategies addressing metabolic and fibrotic components. Drawing parallels to HCV’s success, this review emphasizes advancing diagnostics and therapies for MASH. Developing effective, patient-specific therapies is crucial to closing the gap between MASH and better-managed liver diseases, optimizing care for this growing health challenge.

Dietary soy protein reverses obesity-induced liver steatosis and alters fecal microbial composition independent of isoflavone level

Introduction

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a major public health concern that is exacerbated by the obesity pandemic. Dietary interventions have the potential to alleviate obesity-associated MASLD through variable mechanisms, including optimizing the gut microbiota. Previously, we reported that soy protein concentrate (SPC) with low or high levels of isoflavone (LIF or HIF) protected young obese Zucker rats from developing liver steatosis. The current study was designed to test whether SPC-LIF and SPC-HIF diets would reverse liver steatosis and alter fecal microbial composition in adult obese Zucker rats with existing steatosis.

Methods

Six-week-old male obese Zucker rats (n = 26) were fed a casein control diet (CAS) for 8 weeks and 7 rats were randomly selected and sacrificed to confirm liver steatosis. The remaining rats were randomly assigned to receive CAS, SPC-LIF, or SPC-HIF diet (n = 6-7/group) for an additional 10 weeks.

Results

Compared to CAS diet, feeding SPC-LIF and SPC-HIF diets resulted in significantly lower liver weight, liver steatosis score, and liver microvesicular score (p < 0.05), but did not lead to difference in body weight, liver macrovesicular score, serum ALT, or serum AST. Isoflavone levels (e.g., LIF vs. HIF) did not affect any of these measurements except in the SPC-HIF group, which had an additional decrease in liver weight (p < 0.05) compared to the SPC-LIF group. The SPC-HIF group also had significantly higher levels of the aglycone forms of daidzein, genistein, and equol as well as the total levels of daidzein, genistein, and equol compared to SPC-LIF or CAS diet fed rats (p < 0.05). The distribution of microbial communities based on measures of beta diversity of both SPC-LIF and SPC-HIF groups were significantly different to that of the CAS group (p ≤ 0.005). Alpha-diversity did not differ between any of the groups.

Conclusion

Taken together, dietary soy protein can reverse liver steatosis in adult Zucker rats, and the reversal of steatosis is accompanied by alterations in gut microbial composition.

The activation of TLR4-MyD88 signaling promotes hepatic dysfunction and fibrotic changes in SD rats resulting from prolonged exposure to sodium arsenite

Arsenic, a poisonous metalloid element, is linked to liver diseases, but the exactmechanisms for this process are not yet to be completely elucidated. Toll like receptor 4 (TLR4), acting as a pathogenic pattern recognition receptor, plays a pivotal role in various inflammatory diseases via the myeloid differentiation factor 88 (MyD88) pathway. This study aims to investigate the involvement of the TLR4-MyD88 signaling pathway in liver injury induced by prolonged exposure to sodium arsenite (NaAsO2) in Sprague-Dawley rats. Our research findings demonstratethe activation of TLR4-MyD88 signaling pathway in long-term NaAsO2-exposed rat liver tissues, leading to a significant release of inflammatory factors, which suggests its potential involvement in the pathogenesis of NaAsO2-induced liver injury. We further administered lipopolysaccharide (LPS), a natural ligand of TLR4, and TAK-242, a specific inhibitor of TLR4, to rats in order to validate the specific involvement of the TLR4-MyD88 signaling pathway in NaAsO2-induced liver injury. The results showed that, 1 mg/kg.bw LPS treatment significantly activated TLR4-MyD88 signalling pathway and its mediated pro-inflammatory factors, leading to up-regulation of activation indicators in hepatic stellate cells (HSCs) as well as increased secretion levels of extracellular matrix (ECM) in the liver, and ultimately induced liver fibrosis and dysfunction in rats. Relevantly, subsequent administration of 0.5 mg/kg.bw TAK-242 significantly attenuated the expression levels of TLR4 and its associated proteins, mitigated collagen deposition, and partially improved liver fibrosis and dysfunction caused by NaAsO2 in rats. Our study fully confirms the pivotal role of the TLR4-MyD88 signaling in promoting liver injury induced by NaAsO2, thereby providing a novel molecular target for preventing and treating patients with arsenic poisoning-related liver injury.

What defines a healthy gut microbiome?

The understanding that changes in microbiome composition can influence chronic human diseases and the efficiency of therapies has driven efforts to develop microbiota-centred therapies such as first and next generation probiotics, prebiotics and postbiotics, microbiota editing and faecal microbiota transplantation. Central to microbiome research is understanding how disease impacts microbiome composition and vice versa, yet there is a problematic issue with the term 'dysbiosis', which broadly links microbial imbalances to various chronic illnesses without precision or definition. Another significant issue in microbiome discussions is defining 'healthy individuals' to ascertain what characterises a healthy microbiome. This involves questioning who represents the healthiest segment of our population-whether it is those free from illnesses, athletes at peak performance, individuals living healthily through regular exercise and good nutrition or even elderly adults or centenarians who have been tested by time and achieved remarkable healthy longevity.This review advocates for delineating 'what defines a healthy microbiome?' by considering a broader range of factors related to human health and environmental influences on the microbiota. A healthy microbiome is undoubtedly linked to gut health. Nevertheless, it is very difficult to pinpoint a universally accepted definition of 'gut health' due to the complexities of measuring gut functionality besides the microbiota composition. We must take into account individual variabilities, the influence of diet, lifestyle, host and environmental factors. Moreover, the challenge in distinguishing causation from correlation between gut microbiome and overall health is presented.The review also highlights the resource-heavy nature of comprehensive gut health assessments, which hinders their practicality and broad application. Finally, we call for continued research and a nuanced approach to better understand the intricate and evolving concept of gut health, emphasising the need for more precise and inclusive definitions and methodologies in studying the microbiome.

A Systematic Review of Metabolic Syndrome: Key Correlated Pathologies and Non-Invasive Diagnostic Approaches

Background and Objectives: Metabolic syndrome (MetS) is a condition marked by a complex array of physiological, biochemical, and metabolic abnormalities, including central obesity, insulin resistance, high blood pressure, and dyslipidemia (characterized by elevated triglycerides and reduced levels of high-density lipoproteins). The pathogenesis develops from the accumulation of lipid droplets in the hepatocyte (steatosis). This accumulation, in genetically predisposed subjects and with other external stimuli (intestinal dysbiosis, high caloric diet, physical inactivity, stress), activates the production of pro-inflammatory molecules, alter autophagy, and turn on the activity of hepatic stellate cells (HSCs), provoking the low grade chronic inflammation and the fibrosis. This syndrome is associated with a significantly increased risk of developing type 2 diabetes mellitus (T2D), cardiovascular diseases (CVD), vascular, renal, pneumologic, rheumatological, sexual, cutaneous syndromes and overall mortality, with the risk rising five- to seven-fold for T2DM, three-fold for CVD, and one and a half-fold for all-cause mortality. The purpose of this narrative review is to examine metabolic syndrome as a "systemic disease" and its interaction with major internal medicine conditions such as CVD, diabetes, renal failure, and respiratory failure. It is essential for internal medicine practitioners to approach this widespread condition in a "holistic" rather than a fragmented manner, particularly in Western countries. Additionally, it is important to be aware of the non-invasive tools available for assessing this condition. Materials and Methods: We conducted an exhaustive search on PubMed up to July 2024, focusing on terms related to metabolic syndrome and other pathologies (heart, Lung (COPD, asthma, pulmonary hypertension, OSAS) and kidney failure, vascular, rheumatological (osteoarthritis, rheumatoid arthritis), endocrinological, sexual pathologies and neoplastic risks. The review was managed in accordance with the PRISMA statement. Finally, we selected 300 studies (233 papers for the first search strategy and 67 for the second one). Our review included studies that provided insights into metabolic syndrome and non-invasive techniques for evaluating liver fibrosis and steatosis. Studies that were not conducted on humans, were published in languages other than English, or did not assess changes related to heart failure were excluded. Results: The findings revealed a clear correlation between metabolic syndrome and all the pathologies above described, indicating that non-invasive assessments of hepatic fibrosis and steatosis could potentially serve as markers for the severity and progression of the diseases. Conclusions: Metabolic syndrome is a multisystem disorder that impacts organs beyond the liver and disrupts the functioning of various organs. Notably, it is linked to a higher incidence of cardiovascular diseases, independent of traditional cardiovascular risk factors. Non-invasive assessments of hepatic fibrosis and fibrosis allow clinicians to evaluate cardiovascular risk. Additionally, the ability to assess liver steatosis may open new diagnostic, therapeutic, and prognostic avenues for managing metabolic syndrome and its complications, particularly cardiovascular disease, which is the leading cause of death in these patients.

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.

Carbon monoxide-loaded red blood cells ameliorate metabolic dysfunction-associated steatohepatitis progression via enhancing AMP-activated protein kinase activity and inhibiting Kupffer cell activation

Metabolic dysfunction-associated steatohepatitis (MASH) is a progressive form of nonalcoholic fatty liver disease characterised by fat accumulation, inflammation, oxidative stress, fibrosis, and impaired liver regeneration. In this study, we found that heme oxygenase-1 (HO-1) is induced in both MASH patients and in a MASH mouse model. Further, hepatic carbon monoxide (CO) levels in MASH model mice were >2-fold higher than in healthy mice, suggesting that liver HO-1 is activated as MASH progresses. Based on these findings, we used CO-loaded red blood cells (CO-RBCs) as a CO donor in the liver, and evaluated their therapeutic effect in methionine-choline deficient diet (MCDD)-induced and high-fat-diet (HFD)-induced MASH model mice. Intravenously administered CO-RBCs effectively delivered CO to the MASH liver, where they prevented fat accumulation by promoting fatty acid oxidation via AMP-activated protein kinase (AMPK) activation and peroxisome proliferator-activated receptor induction. They also markedly suppressed Kupffer cell activation and their corresponding anti-inflammatory and antioxidative stress activities in MASH mice. CO-RBCs also helped to restore liver regeneration in mice with HFD-induced MASH by activating AMPK. We confirmed the underlying mechanisms by performing in vitro experiments in RAW264.7 cells and palmitate-stimulated HepG2 cells. Taken together, CO-RBCs show potential as a promising cellular treatment for MASH.

A flavonoid-rich extract of bergamot juice improves high-fat diet-induced intestinal permeability and associated hepatic damage in mice

Consumption of high-fat diets (HFDs) is a contributing factor to obesity, insulin resistance and non-alcoholic fatty liver disease (NAFLD). Several studies suggested the protective role of bioactives present in Citrus fruits against the above mentioned chronic metabolic conditions. In this study, we evaluated if a flavonoid-rich extract of Citrus bergamia (bergamot) juice (BJe) could inhibit HFD-induced intestinal permeability and endotoxemia and, through this mechanism, mitigate the associated hepatic damage in C57BL/6J mice. After 12 weeks of the treatment, HFD consumption caused high body weight (BW) gain, hyperinsulinemia, hyperglycemia, and dyslipidemia, which were mitigated by BJe (50 mg per kg BW) supplementation. Furthermore, supplementation with BJe prevented HFD-induced liver alterations, including increased plasma alanine aminotransferase (ALT) activity, increased hepatic lipid deposition, high NAS, and fibrosis. Mice fed a HFD for 12 weeks showed (i) a decrease in small intestine tight junction protein levels (ZO-1, occludin, and claudin-1), (ii) increased intestinal permeability, and (iii) endotoxemia. All these adverse events were mitigated by BJe supplementation. Linking the capacity of BJe to prevent HFD-associated endotoxemia, supplementation with this extract decreased the HFD-induced overexpression of hepatic TLR-4, downstream signaling pathways (MyD88, NF-κB and MAPK), and the associated inflammation, evidenced by increased MCP-1, TNF-α, IL-6, iNOS, and F4/80 levels. Overall, we suggest that BJe could mitigate the harmful consequences of western style diet consumption on liver physiology by protecting the gastrointestinal tract from permeabilization and associated metabolic endotoxemia.

Chitinase 1: a novel therapeutic target in metabolic dysfunction-associated steatohepatitis

Background

Metabolic dysfunction-associated steatohepatitis (MASH) is characterized by persistent inflammatory cascades, with macrophage activation playing a pivotal role. Chitinase 1 (CHIT1), produced by activated macrophages, is a key player in this cascade. In this study, we aimed to explore the role of CHIT1 in MASH with progressive liver fibrosis.

Methods

Fibrotic liver tissue and serum from distinct patient groups were analyzed using nCounter MAX, flow cytometry, immunohistochemistry, and enzyme-linked immunosorbent assay. A MASH mouse model was constructed to evaluate the effectiveness of OATD-01, a chitinase inhibitor. Macrophage profiling was performed using single-nuclei RNA sequencing and flow cytometry.

Results

CHIT1 expression in fibrotic liver tissues was significantly correlated with the extent of liver fibrosis, macrophages, and inflammation. Single-nuclei RNA sequencing demonstrated a notable increase in macrophages numbers, particularly of lipid-associated macrophages, in MASH mice. Treatment with OATD-01 reduced non-alcoholic fatty liver disease activity score and Sirius red-positive area. Additionally, OATD-01-treated mice had lower CHIT1, F4/80, and α-smooth muscle actin positivity, as well as significantly lower levels of inflammatory markers, pro-fibrotic genes, and matrix remodeling-related mRNAs than vehicle-treated mice. Although the population of F4/80+CD11b+ intrahepatic mononuclear phagocytes remained unchanged, their infiltration and activation (CHIT1+MerTK+) significantly decreased in OATD-01-treated mice, compared with that observed in vehicle-treated mice.

Conclusions

Our study underscores the pivotal role of CHIT1 in MASH. The observed significant improvement in inflammation and hepatic fibrosis, particularly at higher doses of the CHIT1 inhibitor, strongly suggests the potential of CHIT1 as a therapeutic target in MASH accompanied by progressive liver fibrosis.

YAP activation in liver macrophages via depletion of MST1/MST2 enhances liver inflammation and fibrosis in MASLD

Macrophages have been recognized as pivotal players in the progression of MASLD/MASH. However, the molecular mechanisms underlying their multifaceted functions in the disease remain to be further clarified. In the current study, we developed a new mouse model with YAP activation in macrophages to delineate the effect and mechanism of YAP signaling in the pathogenesis of MASLD/MASH. Genetically modified mice, featuring specific depletion of both Mst1 and Mst2 in macrophages/monocytes, were generated and exposed to a high-fat diet for 12 weeks to induce MASLD. Following this period, livers were collected for histopathological examination, and liver non-parenchymal cells were isolated and subjected to various analyses, including single-cell RNA-sequencing, immunofluorescence and immunoblotting and qRT-PCR to investigate the impact of YAP signaling on the progression of MASLD. Our data revealed that Mst1/2 depletion in liver macrophages enhanced liver inflammation and fibrosis in MASLD. Using single-cell RNA-sequencing, we showed that YAP activation via Mst1/2 depletion upregulated the expressions of both pro-inflammatory genes and genes associated with resolution/tissue repair. We observed that YAP activation increases Kupffer cell populations (i.e., Kupffer-2 and Kupffer-3) which are importantly implicated in the pathogenesis of MASLD/MASH. Our data indicate that YAP activation via Mst1/2 deletion enhances both the pro-inflammatory and tissue repairing functions of Kupffer-1 and -2 cells at least in part through C1q. These YAP-regulatory mechanisms control the plasticity of liver macrophages in the context of MASLD/MASH. Our findings provide important evidence supporting the critical regulatory role of YAP signaling in liver macrophage plasticity and the progression of MASLD. Therefore, targeting the Hippo-YAP pathway may present a promising therapeutic strategy for the treatment of MASH.

Targeting Gut Microbiota with Probiotics and Phenolic Compounds in the Treatment of Atherosclerosis: A Comprehensive Review

Atherosclerosis (AS) is a chronic inflammatory vascular disease. Dysregulated lipid metabolism, oxidative stress, and inflammation are the major mechanisms implicated in the development of AS. In addition, evidence suggests that gut dysbiosis plays an important role in atherogenesis, and modulation of the gut microbiota with probiotics and phenolic compounds has emerged as a promising strategy for preventing and treating AS. It has been shown that probiotics and phenolic compounds can improve atherosclerosis-related parameters by improving lipid profile, oxidative stress, and inflammation. In addition, these compounds may modulate the diversity and composition of the gut microbiota and improve atherosclerosis. The studies evaluated in the present review showed that probiotics and phenolic compounds, when consumed individually, improved atherosclerosis by modulating the gut microbiota in various ways, such as decreasing gut permeability, decreasing TMAO and LPS levels, altering alpha and beta diversity, and increasing fecal bile acid loss. However, no study was found that evaluated the combined use of probiotics and phenolic compounds to improve atherosclerosis. The available literature highlights the synergistic potential between phenolic compounds and probiotics to improve their health-promoting properties and functionalities. This review aims to summarize the available evidence on the individual effects of probiotics and phenolic compounds on AS, while providing insights into the potential benefits of nutraceutical approaches using probiotic strains, quercetin, and resveratrol as potential adjuvant therapies for AS treatment through modulation of the gut microbiota.

Ginger essential oil prevents NASH progression by blocking the NLRP3 inflammasome and remodeling the gut microbiota-LPS-TLR4 pathway in mice

BACKGROUND

Diet and gut microbiota contribute to non-alcoholic steatohepatitis (NASH) progression. High-fat diets (HFDs) change gut microbiota compositions, induce gut dysbiosis, and intestinal barrier leakage, which facilitates portal influx of pathogen-associated molecular patterns including lipopolysaccharides (LPS) to the liver and triggers inflammation in NASH. Current therapeutic drugs for NASH have adverse side effects; however, several foods and herbs that exhibit hepatoprotection could be an alternative method to prevent NASH.

METHODS

We investigated ginger essential oil (GEO) against palm oil-containing HFDs in LPS-injected murine NASH model.

RESULTS

GEO reduced plasma alanine aminotransferase levels and hepatic pro-inflammatory cytokine levels; and increased antioxidant catalase, glutathione reductase, and glutathione levels to prevent NASH. GEO alleviated hepatic inflammation through mediated NLR family pyrin domain-containing 3 (NLRP3) inflammasome and LPS/Toll-like receptor four (TLR4) signaling pathways. GEO further increased beneficial bacterial abundance and reduced NASH-associated bacterial abundance.

CONCLUSION

This study demonstrated that GEO prevents NASH progression which is probably associated with the alterations of gut microbiota and inhibition of the LPS/TLR4/NF-κB pathway. Hence, GEO may offer a promising application as a dietary supplement for the prevention of NASH.

Polyphenols improve non-alcoholic fatty liver disease via gut microbiota: A comprehensive review

Polyphenols, natural micronutrients derived from plants, are valued for their anti-inflammatory and antioxidant properties. The escalating global prevalence of non-alcoholic fatty liver disease (NAFLD) underscores its status as a chronic progressive liver condition. Furthermore, the dysregulation of gut microbiota (GM) is implicated in the onset and progression of NAFLD through the actions of metabolites such as bile acids (BAs), lipopolysaccharide (LPS), choline, and short-chain fatty acids (SCFAs). Additionally, GM may influence the integrity of the intestinal barrier. This review aims to evaluate the potential effects of polyphenols on GM and intestinal barrier function, and their subsequent impact on NAFLD. We searched through a wide range of databases, such as Web of Science, PubMed, EMBASE, and Scopus to gather information for our non-systematic review of English literature. GM functions and composition can be regulated by polyphenols such as chlorogenic acid, curcumin, green tea catechins, naringenin, quercetin, resveratrol, and sulforaphane. Regulating GM composition improves NAFLD by alleviating inflammation, liver fat accumulation, and liver enzymes. Furthermore, it improves serum lipid profile and gut barrier integrity. All of these components affect NAFLD through the metabolites of GM, including SCFAs, choline, LPS, and BAs. Current evidence indicates that chlorogenic acid, resveratrol, quercetin, and curcumin can modulate GM, improving intestinal barrier integrity and positively impacting NAFLD. More studies are necessary to evaluate the safety and efficacy of naringenin, sulforaphane, and catechin.

High methionine intake alters gut microbiota and lipid profile and leads to liver steatosis in mice

Methionine is an important sulfur-containing amino acid. Health effects of both methionine restriction (MR) and methionine supplementation (MS) have been studied. This study aimed to investigate the impact of a high-methionine diet (HMD) (1.64% methionine) on both the gut and liver functions in mice through multi-omic analyses. Hepatic steatosis and compromised gut barrier function were observed in mice fed the HMD. RNA-sequencing (RNA-seq) analysis of liver gene expression patterns revealed the upregulation of lipid synthesis and degradation pathways, cholesterol metabolism and inflammation-related nucleotide-binding oligomerization domain (NOD)-like receptor signaling pathway. Metagenomic sequencing of cecal content demonstrated a shift in gut microbial composition with an increased abundance of opportunistic pathogens and gut microbial functions with up-regulated lipopolysaccharide (LPS) biosynthesis in mice fed HMD. Metabolomic study of cecal content showed an altered gut lipid profile and the level of bioactive lipids, including docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), palmitoylethanolamide (PEA), linoleoyl ethanolamide (LEA) and arachidonoyl ethanolamide (AEA), that carry anti-inflammatory effects significantly reduced in the gut of mice fed the HMD. Correlation analysis demonstrated that gut microbiota was highly associated with liver and gut functions and gut bioactive lipid content. In conclusion, this study suggested that the HMD exerted negative impacts on both the gut and liver, and an adequate amount of methionine intake should be carefully determined to ensure normal physiological function without causing adverse effects.

Toxic and essential metals: metabolic interactions with the gut microbiota and health implications

Human exposure to heavy metals, which encompasses both essential and toxic varieties, is widespread. The intestine functions as a critical organ for absorption and metabolism of heavy metals. Gut microbiota plays a crucial role in heavy metal absorption, metabolism, and related processes. Toxic heavy metals (THMs), such as arsenic (As), mercury (Hg), lead (Pb), and cadmium (Cd), can cause damage to multiple organs even at low levels of exposure, and it is crucial to emphasize their potential high toxicity. Nevertheless, certain essential trace elements, including iron (Fe), copper (Cu), and manganese (Mn), play vital roles in the biochemical and physiological functions of organisms at low concentrations but can exert toxic effects on the gut microbiota at higher levels. Some potentially essential micronutrients, such as chromium (Cr), silicon (Si), and nickel (Ni), which were considered to be intermediate in terms of their essentiality and toxicity, had different effects on the gut microbiota and their metabolites. Bidirectional relationships between heavy metals and gut microbiota have been found. Heavy metal exposure disrupts gut microbiota and influences its metabolism and physiological functions, potentially contributing to metabolic and other disorders. Furthermore, gut microbiota influences the absorption and metabolism of heavy metals by serving as a physical barrier against heavy metal absorption and modulating the pH, oxidative balance, and concentrations of detoxification enzymes or proteins involved in heavy metal metabolism. The interactions between heavy metals and gut microbiota might be positive or negative according to different valence states, concentrations, and forms of the same heavy metal. This paper reviews the metabolic interactions of 10 common heavy metals with the gut microbiota and their health implications. This collated information could provide novel insights into the disruption of the intestinal microbiota caused by heavy metals as a potential contributing factor to human diseases.

Gut microbial metabolites in MASLD: Implications of mitochondrial dysfunction in the pathogenesis and treatment

With an increasing prevalence, metabolic dysfunction-associated steatotic liver disease (MASLD) has become a major global health problem. MASLD is well-known as a multifactorial disease. Mitochondrial dysfunction and alterations in the gut bacteria are 2 vital events in MASLD. Recent studies have highlighted the cross-talk between microbiota and mitochondria, and mitochondria are recognized as pivotal targets of the gut microbiota to modulate the host's physiological state. Mitochondrial dysfunction plays a vital role in MASLD and is associated with multiple pathological changes, including hepatocyte steatosis, oxidative stress, inflammation, and fibrosis. Metabolites are crucial mediators of the gut microbiota that influence extraintestinal organs. Additionally, regulation of the composition of gut bacteria may serve as a promising therapeutic strategy for MASLD. This study reviewed the potential roles of several common metabolites in MASLD, emphasizing their impact on mitochondrial function. Finally, we discuss the current treatments for MASLD, including probiotics, prebiotics, antibiotics, and fecal microbiota transplantation. These methods concentrate on restoring the gut microbiota to promote host health.

Gut Microbiota and Sinusoidal Vasoregulation in MASLD: A Portal Perspective

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a common condition with heterogeneous outcomes difficult to predict at the individual level. Feared complications of advanced MASLD are linked to clinically significant portal hypertension and are initiated by functional and mechanical changes in the unique sinusoidal capillary network of the liver. Early sinusoidal vasoregulatory changes in MASLD lead to increased intrahepatic vascular resistance and represent the beginning of portal hypertension. In addition, the composition and function of gut microbiota in MASLD are distinctly different from the healthy state, and multiple lines of evidence demonstrate the association of dysbiosis with these vasoregulatory changes. The gut microbiota is involved in the biotransformation of nutrients, production of de novo metabolites, release of microbial structural components, and impairment of the intestinal barrier with impact on innate immune responses, metabolism, inflammation, fibrosis, and vasoregulation in the liver and beyond. The gut-liver axis is a conceptual framework in which portal circulation is the primary connection between gut microbiota and the liver. Accordingly, biochemical and hemodynamic attributes of portal circulation may hold the key to better understanding and predicting disease progression in MASLD. However, many specific details remain hidden due to limited access to the portal circulation, indicating a major unmet need for the development of innovative diagnostic tools to analyze portal metabolites and explore their effect on health and disease. We also need to safely and reliably monitor portal hemodynamics with the goal of providing preventive and curative interventions in all stages of MASLD. Here, we review recent advances that link portal metabolomics to altered sinusoidal vasoregulation and may allow for new insights into the development of portal hypertension in MASLD.

The role of short-chain fatty acids in the progression of non-alcoholic fatty liver disease

Introduction. Nowadays, a multifactorial model of the pathogenesis of NAFLD is recognized. It is interesting to study the contribution of changes in the composition of the intestinal microbiota and its metabolites in the development of the disease.

Aim. To evaluate the contribution of research into the qualitative composition of the intestinal microbiota in relation to the risk of progression of NAFLD to reduce the loss of health- saving potential of the population.

Materials and methods. An open comparative study of 83 mature-aged patients (56.6 years (46–63)) suffering from NAFLD was conducted. The levels of insulin, leptin, its receptor, adiponectin in blood serum, zonulin in feces were studied, and SCFA in feces

was determined. The analysis was carried out depending on the phenotypes of NAFLD: the degree of steatosis (1 – 40 patients, degree 2 – 18 and degree 3 – 25), the presence of NASH (43 patients), the presence of fibrosis (fibrosis was found in 35 patients). The degree of steatosis and fibrosis was assessed using elastometry. The results of the study were analyzed using the Microsoft Excel, STATISTICA 12.0 software package.

Results. In patients with NAFLD, the absolute number of all SCFA in the feces was reduced. The anaerobic index was deviated towards sharply negative values (-0,711 (-0,576-(-0,830)). A high level of propionic acid was noted among the patients with fibrosis (p < 0.05). Anaerobic index, relative content of isoC4 + isoC5 + isoC6, relative content of butyric acid had a positive relationship with the St-index (rs = 0.254, rs = 0.269, rs = 0.240, p≤ 0.05). An increase in the relative amount of propionic acid was statistically significantly associated with a decrease of FLI (rs = -0.229, p ≤0.05). A positive correlation was found between the level of insulin and the absolute amount of butyric acid C4 (rs = 0.228, p ≤ 0.05). There was an inverse relationship of the absolute and relative amounts of isoC4+ isoC5 + isoC6 and Iso Cn/Cn with zonulin in the feces (rs = -0.231, p ≤ 0.05, rs = -0.380, p ≤ 0.05 and rs = -0.332, p ≤ 0.05, respectively).

Conclusion. There is the anaerobic flora among the patients with NAFLD. Modification of the content of SCFA in feces may affect to the progression of NAFLD. The effect of SCFA on the development and progression of NAFLD may be mediated by the development of insulin and leptin resistance, as well as an integrity violation of the intestinal barrier.