Metabolic dysfunction-associated steatotic liver disease: epidemiological trends, risk factors, and the role of gut microbiota in disease progression (a literature review)

NAFLD vs. MAFLD – It is not the name but the disease that decides the outcome in fatty liver

Changing Nomenclature from Nonalcoholic Fatty Liver Disease to Metabolic Dysfunction-Associated Fatty Liver Disease – Not Only Premature But Also Confusing

Nonalcoholic fatty liver disease is the most prevalent chronic liver disease worldwide. It is now updated as metabolic dysfunction-associated steatotic liver disease (MASLD). The progression of MASLD to hepatocellular carcinoma (HCC) involves complex mechanisms, with the gut microbiota (GM) and its metabolites playing a pivotal role in this transformation through the "gut-liver axis." This review systematically summarizes the characteristics of GM dysbiosis in patients with MASLD and the regulatory mechanisms of its metabolites (e.g., short-chain fatty acids, secondary bile acids, trimethylamine N-oxide, and lipopolysaccharides) in the progression from MASLD to HCC. Short-chain fatty acids exert protective effects in the early stages by enhancing the intestinal barrier and modulating immune and metabolic responses. However, metabolic disturbances, such as the "paradoxical effect" of butyrate and the lipogenic effect of acetate, may promote the formation of a tumor microenvironment in the later stages. Secondary bile acids (e.g., deoxycholic acid) exacerbate liver fibrosis and carcinogenesis by activating inflammatory pathways (nuclear factor-κB and mitogen-activated protein kinase), inducing oxidative stress, and inhibiting foresaid X receptor signaling. Trimethylamine N-oxide directly drives HCC progression by activating the mitogen-activated protein kinase/nuclear factor-κB pathway, promoting epithelial-mesenchymal transition, and creating an immunosuppressive microenvironment. Lipopolysaccharide accelerates fibrosis and metabolic reprogramming through toll-like receptor 4-mediated chronic inflammation and hepatic stellate cell activation. This review highlights that the dynamic changes in GM metabolites are closely associated with MASLD-HCC progression. Specific monitoring of these metabolites may serve as potential biomarkers for early detection. Furthermore, gut-targeted therapies (e.g., fecal microbiota transplantation) have shown translational potential. Future studies are needed to further validate their clinical value and develop precise prevention and treatment strategies.

There is a closely relationship between the development and progression of nonalcoholic fatty liver disease (NAFLD) or metabolic associated fatty liver disease (MAFLD) and obesity and diabetes. NAFLD fibrosis scores should be routinely used to rule out patients with advanced fibrosis. High scores may help identify patients at higher risk of all causes andliverrelated morbidity and mortality. The aim of this study was to investigate the association between exenatide and fibrosis scores. The effect of exenatide treatment on fibrosis scores was evaluated in type 2 diabetes mellitus (DM) patients with MAFLD. Evaluation was made of 50 patients with type 2 DM and MAFLD. The NFS, FIB4 and APRI scores were calculated before and after 6 months of treatment. After 6 months of exenatide treatment, the NFS and APRI scores were determined to have decreased significantly. Exenatide was observed to control blood glucose, reduce body weight and improve fibrosis scores in MAFLD patients with type 2 diabetes.

As the most prevalent hepatic disorder worldwide, metabolic dysfunction-associated steatotic liver disease (MASLD) afflicts over one-third of the global population, representing a significant public health challenge. The multifactorial pathogenesis of this condition is principally rooted in metabolic dysregulation. It is notable that emerging evidence highlights a critical role for gut microbiota (GM) in disease initiation and progression. This comprehensive review elaborates some representative GM species that influence hepatic lipid metabolism and elucidates the mechanisms through which GM dysbiosis exacerbates MASLD pathogenesis. Importantly, the positive or negative effects of intestinal bacterial communities on MASLD are largely dependent on their special metabolites, such as short chain fatty acids, ethanol, and trimethylamine N-oxide. Current therapeutic strategies targeting GM modulation, including prebiotics, probiotics, fecal microbiota transplantation, specific medicines, and bacteriphages, demonstrate promising efficacy that partially restores microbial equilibrium and mitigates hepatic steatosis. Although limitations still persist in achieving sustained clinical remission, the expanding frontier of microbiome research continues to refine our understanding of host-microbiota crosstalk in MASLD. Future investigations integrating multiple approaches and longitudinal clinical data hold potential to unravel complex microbial networks, paving the way for innovative therapeutic breakthroughs in metabolic liver disease management.

Metabolic Associated Steatosis Liver Disease (MASLD) and its advanced form, Metabolic Associated Steatohepatitis (MASH), represent growing global health concerns closely linked to obesity, type 2 diabetes mellitus (T2DM), and metabolic syndrome. The gut microbiome has emerged as a key modulator in MASLD pathogenesis through the gut–liver axis, influencing hepatic fat accumulation, inflammation, and fibrosis via microbial metabolites and immune responses. Dysbiosis–characterized by altered microbial diversity and composition–contributes to hepatic lipid dysregulation, systemic inflammation, and impaired bile acid signaling. Metabolites such as short-chain fatty acids (SCFAs), trimethylamine-N-oxide (TMAO), and ethanol play critical roles in disease progression. Recent innovations in precision medicine, including microbiome profiling, metabolomics, and genomics, offer promising diagnostic and therapeutic strategies. Targeted probiotics, fecal microbiota transplantation (FMT), and personalized dietary interventions are under investigation for modulating the gut microbiome. This systematic review, conducted in accordance with PRISMA 2020 guidelines, is the first to comprehensively integrate both animal and human studies on MASLD/MASH-related gut microbiome alterations. It uniquely synthesizes microbial taxa, functional metabolites, and region-specific patterns–including data from underrepresented MENA populations. Eligible studies from PubMed, Scopus, and Web of Science evaluated microbial composition, metabolite profiles, and associations with steatosis, inflammation, and fibrosis. The findings underscore the diagnostic and therapeutic potential of microbiome modulation and emphasize the need for longitudinal, mechanistically driven studies. This systematic review is the first to integrate both animal and human studies on MASLD/MASH-related gut microbiome alterations. Unlike previous reviews, it uniquely emphasizes microbial taxa, functional metabolites, and region-specific patterns, including underrepresented MENA populations. By synthesizing findings from diverse cohorts, this review highlights diagnostic and therapeutic opportunities while identifying persistent gaps in longitudinal data, regional representation, and multi-omics integration.

The gut microbiota is increasingly considered a contributory factor in metabolic dysfunction-associated steatotic liver disease (MASLD). This double-blind RCT evaluated the effect of three consecutive fecal microbiota transplantations (FMT) on hepatic steatosis in MASLD. Twenty patients with MASLD were randomized (1:1) to receive allogeneic or autologous FMTs at weeks 0, 3, and 6, with follow-up through week 12. FMT material was derived from two donors. We assessed changes in hepatic steatosis (magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF)), glucose tolerance (oral glucose tolerance test), liver biochemistry, and gut microbiota composition/engraftment. Change in MRI-PDFF from baseline to week 12 was not significantly different between groups (p = 0.50). Liver biochemistry and glucose tolerance also showed no significant overall changes. Patients’ stool microbiota exhibited high baseline alpha diversity and similar composition across treatment groups, diverging by week 12 (p = 0.02). Two microbial taxa belonging to the families Gastranaerophilaceae and Rikenellaceae were associated with triglyceride levels after FMT. No further microbiota signatures were associated with FMT-treatment or response. Donor microbiota engraftment appeared donor-specific, but not treatment- or response-specific. In conclusion, FMT did not significantly affect hepatic steatosis, glucose tolerance, liver biochemistry, or gut microbiota signatures. Future studies should consider including patients with low microbiota diversity. Dutch Trial Register: NL-OMON48776; Central Committee on Research Involving Human Subjects: NL66705.058.18; Clinicaltrials.gov: NCT04465032.

Yet more evidence that MAFLD is more than a name change

Gut microbiome and metabolic dysfunction-associated steatotic liver disease: Pathogenic role and potential for therapeutics

ObjectiveCircular RNAs belong to a category of noncoding RNAs that feature a unique continuous, covalently bonded ring configuration. Recent research indicates that circular RNAs are essential for the development of metabolic dysfunction-associated steatotic liver disease. This study sought to examine the functional role and molecular mechanism of circDock6 in metabolic dysfunction-associated steatotic liver disease.MethodsQuantitative reverse transcription polymerase chain reaction was performed to determine circDock6 expression patterns in liver tissues from high-fat diet- and standard diet-fed mice in vivo. Triglyceride detection, western blot analysis, and oil red O staining were performed to evaluate the regulatory effect of circDock6 on metabolic dysfunction-associated steatotic liver disease in vitro.ResultsCircDock6 was found to be markedly overexpressed in high-fat diet liver tissues compared with that in standard diet tissues. Moreover, knockdown of circDock6 expression lowered triglyceride content and lipid droplet formation. Mechanistically, circDock6 acted as a molecular sponge for mmu-let-7g-5p, which regulated insulin-like growth factor 1 receptor expression and contributed to the progression of metabolic dysfunction-associated steatotic liver disease. CircDock6 knockdown suppressed metabolic dysfunction-associated steatotic liver disease progression by modulating insulin-like growth factor 1 receptor via mmu-let-7g-5p targeting.ConclusionOur study identified circDock6 as a novel regulator of metabolic dysfunction-associated steatotic liver disease pathogenesis through the mmu-let-7g-5p/insulin-like growth factor 1 receptor axis, indicating its potential as a therapeutic target for metabolic dysfunction-associated steatotic liver disease intervention.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is currently the most prevalent cause of chronic liver disease worldwide. Its pathogenesis is complex and not yet fully elucidated but is commonly explained by the “multiple hit” hypothesis, which suggests that pathological behaviours interact with an unfavourable genetic background and the presence of cardiovascular comorbidities. Recent evidence has highlighted a potential role of the gut microbiota in the onset and progression of MASLD to metabolic dysfunction-associated steatohepatitis (MASH) and hepatocellular carcinoma (HCC), potentially driven by epigenetic modifications mediated by microRNAs (miRNAs). MiRNAs are small, non-coding RNAs that regulate gene expression both intra- and extracellularly. Notably, emerging data suggests a bidirectional communication between the gut microbiota and the host, mediated by miRNAs via exosomes and outer membrane vesicles. The primary aim of this review is to explore the epigenetic crosstalk between the host and the gut microbiota through miRNA expression, with the goal of identifying specific pathways involved in MASLD development and natural history. A secondary objective is to evaluate the potential applications of artificial intelligence in the analysis of these complex host–microbiota interactions, to standardize the evaluation of microbiota and to create a model of the epigenetic changes in metabolic liver disease.

BackgroundA number of epidemiological studies have suggested an association between metabolic dysfunction-associated fatty liver disease (MAFLD) and the incidence of atrial fibrillation (AF). However, the pathogenesis leading to AF in the context of MAFLD remains unclear. We therefore aimed at assessing the impact of MAFLD and liver fibrosis status on left atrium (LA) structure and function.MethodsPatients with a Fatty Liver Index (FLI) >60 and the presence of metabolic comorbidities were classified as MAFLD+. In MAFLD+ patients, liver fibrosis severity was defined using the non-alcoholic fatty liver disease (NAFLD) Fibrosis Score (NFS), as follows: MAFLD w/o fibrosis (NFS ≦ −1.455), MAFLD w/indeterminate fibrosis (−1.455 < NFS < 0.675), and MAFLD w/fibrosis (NFS ≧ 0.675). In the first cohort of patients undergoing AF ablation, the structural and functional impact on LA of MAFLD was assessed by LA strain analysis and endocardial voltage mapping. Histopathological assessment of atrial fibrosis was performed in the second cohort of patients undergoing cardiac surgery. Finally, the impact of MAFLD on AF recurrence following catheter ablation was assessed.ResultsIn the AF ablation cohort (NoMAFLD n = 123; MAFLD w/o fibrosis n = 37; MAFLD indeterm. fibrosis n = 75; MAFLD w/severe fibrosis n = 10), MAFLD patients with high risk of F3–F4 liver fibrosis presented more LA low-voltage areas as compared to patients without MAFLD (16.5 [10.25; 28] vs 5.0 [1; 11] low-voltage areas p = 0.0115), impaired LA reservoir function assessed by peak left atrial longitudinal strain (19.7% ± 8% vs 8.9% ± 0.89% p = 0.0268), and increased LA volume (52.9 ± 11.7 vs 43.5 ± 18.0 ml/m2 p = 0.0168). Accordingly, among the MAFLD patients, those with a high risk of F3–F4 liver fibrosis presented a higher rate of AF recurrence during follow-up (p = 0.0179). In the cardiac surgery cohort (NoMAFLD n = 12; MAFLD w/o fibrosis n = 5; MAFLD w/fibrosis n = 3), an increase in histopathological atrial fibrosis was observed in MAFLD patients with a high risk of F3–F4 liver fibrosis (p = 0.0206 vs NoMAFLD; p = 0.0595 vs MAFLD w/o fibrosis).ConclusionIn conclusion, we found that liver fibrosis scoring in MAFLD patients is associated with adverse atrial remodeling and AF recurrences following catheter ablation. The impact of the management of MAFLD on LA remodeling and AF ablation outcomes should be assessed in dedicated studies.

Fecal microbiota transplantation (FMT) restores a balanced intestinal flora, which helps to cure recurrent Clostridium difficile infections (RCDI). FMT has also been used to treat other gastrointestinal diseases, including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and chronic constipation, as well as a variety of non-GI disorders. The purpose of this review is to discuss gut microbiota and FMT treatment of GI and non-GI diseases. An imbalanced gut microbiota is known to predispose one to Clostridium difficile infections (CDI), IBD, and IBS. However, the complex role of the gut microbiota in maintaining health is a newer concept that is being increasingly studied. The microbiome plays a major role in cellular immunity and metabolism and has been implicated in the pathogenesis of non-GI autoimmune diseases, chronic fatigue syndrome, obesity, and even some neuropsychiatric disorders. Many recent studies have reported that viral gastroenteritis can affect intestinal epithelial cells, and SARS-CoV-2 virus has been identified in the stool of infected patients. FMT is a highly effective cure for RCDI, but a better understanding of the gut microbiota in maintaining health and controlled studies of FMT in a variety of conditions are needed before FMT can be accepted and used clinically.

Fecal Microbiota Transplantation for Ulcerative Colitis: Not Just Yet

Obesity is a growing global health issue affecting both developed and developing countries. Despite various preventive efforts, the prevalence of obesity continues to rise. One of the emerging approaches in managing obesity and its complications is by modulating gut microbiota balance. Gut microbiota plays a significant role in energy metabolism, inflammation regulation, and insulin sensitivity. An imbalance in gut microbiota, known as dysbiosis, is frequently observed in obese individuals and has been associated with increased insulin resistance, a key feature of type 2 diabetes mellitus. This study aims to systematically review the relationship between gut microbiota imbalance and insulin resistance in obese patients, based on literature from 2016 to 2024. The literature search was conducted through accredited databases such as PubMed, Google Scholar, and others using the keywords “Gut Microbes,” “Insulin Resistance,” and “Obesity.” From 500 initial articles, 10 highly relevant journals were selected for further analysis. The review findings reveal a strong association between dysbiosis and increased insulin resistance through various mechanisms, including short-chain fatty acid (SCFA) production, activation of inflammatory pathways, and disruption of glucose metabolism. Several studies also suggest that interventions such as probiotics, prebiotics, and fecal microbiota transplantation may improve insulin sensitivity. However, more longitudinal and interventional studies are needed to establish a strong causal relationship. These findings highlight the importance of maintaining gut microbiota balance as a potential strategy in managing obesity and insulin resistance.