Metabolic-Dysfunction-Associated Fatty Liver Disease and Gut Microbiota: From Fatty Liver to Dysmetabolic Syndrome

Olivetol's Effects on Metabolic State and Gut Microbiota Functionality in Mouse Models of Alimentary Obesity, Diabetes Mellitus Type 1 and 2, and Hypercholesterolemia

BACKGROUND

Disorders of glucose and lipid metabolism, such as obesity, diabetes mellitus, or hypercholesterolemia, can cause serious complications, reduce quality of life, and lead to increased premature mortality. Olivetol, a natural compound, could be proposed as a promising therapeutic agent for preventing, treating, or alleviating metabolic complications of such pathological conditions.

METHODS

In this study, the researchers conducted a broad parallel investigation of olivetol's effects on metabolic state and gut microbiota functionality in mouse models of alimentary obesity, diabetes mellitus type 1 and 2, and hypercholesterolemia.

RESULTS

According to the results of the study, olivetol caused a lowering of body weight in C57Bl6 mice fed a high-fat diet and in ldlr(-/-) mice, decreased serum glucose levels in db/db mice, improved lipid metabolism in ldlr(-/-) mice, and prevented inflammatory infiltration of the pancreas and loss of insulin secretion in NOD mice. In addition, olivetol affected the composition and functional activity of gut microbiota communities, inducing an expansion of probiotic species such as Akkermansia muciniphila and Bacteroides acidifaciens and depleting the representation of pathobionts such as Prevotella, although olivetol supplementation did not influence the diversity or richness of the communities.

CONCLUSIONS

These results suggest that olivetol is a promising therapeutic agent for preventing, treating, or alleviating the metabolic complications of obesity, diabetes mellitus type 1 and 2, and hypercholesterolemia; however, more investigations are required in order to attain a full understanding of its physiological effects.

Therapeutic success in primary biliary cholangitis and gut microbiota: a safe highway?

Primary biliary cholangitis (PBC) is a chronic, cholestatic, autoimmune disease, characterized by destruction of bile ducts. PBC predominantly affects women between 40 and 60 years of age. The presence of antimitochondrial antibodies (AMA) is a serological feature of PBC. These highly specific antibodies are found in about 95% of patients with the disease. The family of enzymes located in the inner membrane of the mitochondria, called the 2-oxo-acid dehydrogenase complex represents the target of the AMA. Ursodeoxycholic acid (UDCA) is a synthetic bile acid capable of protecting cholangiocytes from cholestatic damage caused by the accumulation of bile acids with a mechanism of action not yet well clarified. UDCA represents the gold standard therapy for PBC patients with recommended dose of 13-15 mg/kg/day. However, not every patient responds to therapy. On the other hand, the gut microbiota plays a key role in the onset of PBC through still unclear biochemical pathways. Less is known about its role as a potential biomarker after drug treatment. Actually, few studies analyzed the changes in gut microbiota composition before and after UDCA treatment. For this reason, this review represents an examination of the studies carried out on changes in gut microbiota composition in patients affected by PBC before and after treatment.

Advances in the study of oral microbiota and metabolism associated fatty liver disease: a systematic review

Objective

The oral microbiota is the second largest microbiota in the human body and has a significant impact on human health. Recent evidence suggests that dysbiosis of the oral microbiota may be associated with the development of metabolism-associated fatty liver disease (MAFLD). This review aimed to validate the relationship between oral microbial diversity and the development of MAFLD.

Methods

A systematic evaluation was performed based on PRISMA guidelines. Three independent reviewers searched for relevant literature in several databases, including PubMed/Medline, Web of Science, and Scopus, with a search date ranging from the establishment of the databases to June 2024.

Results

A total of 1278 publications were initially screened, including five cross-sectional studies, seven case-control studies, one cohort study, and one retrospective study. These studies included a total of 3335 patients with MAFLD, 254 patients with MASH, and 105 patients with liver cirrhosis. All 14 included studies concluded that there was a correlation or potential correlation between oral microbiota and MAFLD. Seven studies found that the composition of the oral microbiota in MAFLD patients differed from that of healthy controls, and specific oral bacteria may be associated with an increased incidence of MAFLD. At the phylum level, several studies found differences in the abundance of the phyla Firmicutes, Proteobacteria, and Clostridia compared to healthy controls. Additionally, a study on oral fungi found significant differences in the phyla Proteobacteria and in the genus Staphylococcus between patients with MAFLD and healthy controls. At the genus level, Porphyromonas was studied most frequently, with all 8 studies identifying infection with Porphyromonas as a significant risk factor for pathological progression in MAFLD. Furthermore, a dysbiosis in the ratio of Porphyromonas gingivalis./Porphyromonas anomalies may be an important marker of MAFLD progression.

Conclusion

There is an important association between the diversity of oral microbiota composition and MAFLD. This finding suggests the importance of oral health assessment and monitoring for the prevention or intervention of MAFLD.

The effects of stress on gut virome: Implications on infectious disease and systemic disorders

The role of gut microbiota in health and disease is being thoroughly examined in various contexts, with a specific focus on the bacterial fraction due to its significant abundance. However, despite their lower abundance, viruses within the gut microbiota are gaining recognition for their crucial role in shaping the structure and function of the intestinal microbiota, with significant effects on the host as a whole, particularly the immune system. Similarly, environmental factors such as stress are key in modulating the host immune system, which in turn influences the composition of the gut virome and neurological functions through the bidirectional communication of the gut-brain axis. In this context, alterations in the host immune system due to stress and/or dysbiosis of the gut virome are critical factors in the development of both infectious and noninfectious diseases. The molecular mechanisms and correlation patterns between microbial species are not yet fully understood. This literature review seeks to explore the interconnected relationship between stress and the gut virome, with a focus on how this interaction is influenced by the host's immune system. We also discuss how disturbances in this finely balanced system can lead to the onset and/or progression of diseases.

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.

Metabolic-associated fatty liver disease and pregnancy complications: new challenges and clinical perspectives

The term metabolic-associated fatty liver disease (MAFLD), with a global prevalence estimated at 38.77%, has gradually replaced the traditional concept of non-alcoholic fatty liver disease (NAFLD). Compared to the general population, the incidence of MAFLD is notably higher among pregnant women, posing potential risks to both maternal and neonatal health. This review summarizes the latest research on MAFLD, focusing on its association with pregnancy complications. Additionally, it provides a comparative analysis with previous studies on NAFLD, presenting a comprehensive perspective for clinical management. Findings suggest that pregnant women with MAFLD face a higher risk of gestational hypertension and cesarean delivery compared to those with NAFLD, while the risk for gestational diabetes mellitus remains similar between the two conditions. Additionally, MAFLD is associated with an increased likelihood of delivering large-for-gestational-age infants and heightened risks of preterm birth and low birth weight. Current treatment strategies for MAFLD focus on lifestyle modifications, such as dietary adjustments and increased physical activity. However, there is an urgent need for the development of safe and effective pharmacological treatments, particularly tailored toward pregnant women. Future research should delve deeper into the causal relationships between MAFLD and pregnancy complications and explore optimal therapeutic approaches to improve outcomes for mothers and their infants.

Metabolic Profiles of the Gut Microbiota in Patients with Different Stages of Metabolism Dysfunction-Associated Fatty Liver Disease

   Aim: to study the metabolic activity of the intestinal microbiota depending on the stage of metabolic dysfunction-associated fatty liver disease (MAFLD).

   Materials and methods. The study included 85 patients with MAFLD (27 patients with steatosis without steatohepatitis and fibrosis, 42 patients with steatohepatitis, 16 patients with cirrhosis as an outcome of MAFLD, Child — Pugh class A–B) and 20 healthy people who formed the control group. The level and spectrum of short-chain fatty acids (SCFA) were determined by gas-liquid chromatography.

   Results. It was found that patients with MAFLD at the stage of steatosis and cirrhosis of the liver have unidirectional changes in the metabolic activity of the intestinal microbiota. We established a decrease in the absolute concentrations of SCFA — their total content, the level of acetate, propionate, butyrate, a decrease in the level of isoacids. The SCFA profiles showed an increase in the proportion of acetate and a decrease in propionate and butyrate. Moreover, changes in the named parameters of SCFAs are aggravated with progression to liver cirrhosis. At the stage of steatohepatitis, we identified two subgroups of patients with different levels of metabolic activity of the microbiota. Patients whose microbiota metabolism for SCFA production was high had correspondingly elevated SCFA levels. And, on the contrary, patients in whom the metabolic activity of the microbiota was reduced were characterized by a steady decrease in SCFAs and disease progression to liver cirrhosis. In the study, we showed an inverse correlation between the calculated prognostic indices of NFS and FIB-4, elastography values with the total level of SCFA, the level of acetate, propionate, butyrate. Thus, a decrease in the content of SCFA for patients with MAFLD can be considered as a prognostic marker of an unfavorable course of liver disease.

HO-1-induced autophagy establishes a HO-1-p62-Nrf2 positive feedback loop to reduce gut permeability in cholestatic liver disease

OBJECTIVES

The gut-liver axis disruption is a unified pathogenetic principle of cholestatic liver disease (CSLD). Increased gut permeability is the leading cause of gut-liver axis disruption. HO-1 is capable of protecting against gut-liver axis injury. However, it has rarely been reported whether autophagy is involved in HO-1 protecting gut-liver barrier integrity and the underlying mechanism.

MATERIALS AND METHODS

Mice underwent bile duct ligation (BDL) was established as CSLD model in vivo. Caco-2 cells with LPS treatment was established as in vitro cell model. Immunofluorescence, western blot and transepithelial electrical resistance (TER) assay were used to observe epithelial tight junction (TJ) and autophagy. Liver injury and fibrosis were evaluated as well through H&E staining, masson staining, sirius red staining and ELISA.

RESULTS AND CONCLUSIONS

Our study demonstrated that the epithelial TJ and TER were notably reduced both in BDL mice and in LPS treated intestinal epithelial cells. Increased HO-1 expression could significantly induce intestinal epithelial cell autophagy. Additionally, this increased autophagy level reversed the reduction effects of BDL or LPS on epithelial TJ and TER in vivo and in vitro, therefore decreased transaminase level in serum and relieved liver fibrosis in BDL mice. Besides, increased autophagy level in turn upregulated the expression of HO-1 by p62 degradation of Keap1 and subsequent activation of Nrf2 pathway. Collectively, these results indicate that HO-1 reduces gut permeability by enhancing autophagy level in CSLD, the increased autophagy establishes a HO-1-p62-Nrf2 positive feedback loop to further improve gut-liver axis disruption. Therefore, our study confirms the critical role of autophagy in HO-1 ameliorating gut-liver axis injury during CSLD, highlighting HO-1 as a promising therapeutic target.

Impact of diet and gut microbiota changes in the development of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a primary liver cancer that occurs with a frequency of 85% in patients with liver cirrhosis. It is the sixth most common type of cancer globally. Asia is the continent with the highest incidence (72%), followed by Europe (8%) and Africa (5%). Men are four times more likely than women to develop this cancer, especially in the 70-80 age group. Risk factors include alcoholic liver disease, tobacco use, genetic predisposition, dysmetabolic comorbidities such as type 2 diabetes mellitus and obesity, hepatitis B virus and hepatitis C virus infections, and non-alcoholic fatty liver disease. Unhealthy dietary regimens and gut dysbiosis are additional risk factors that have been recently investigated. These two factors are closely related because the gut microbiota performs several biological functions, including nutrient metabolism, a process that promotes gut homeostasis, known as eubiosis. With regard to the correlation between diet, gut microbiota, and HCC development, there are several mechanisms that have not yet been fully elucidated. This narrative review aims to evaluate the impact of diet and gut microbiota changes in the development of HCC. Our analysis, performed on several clinical and pre-clinical studies, showed that a high-fat diet promotes gut dysbiosis and hepatic fat accumulation, leading to the progression from simple steatosis to HCC, while the Mediterranean diet, rich in fiber and monounsaturated fatty acids, had a protective role. For this reason, international employment of this dietary regimen for therapeutic purposes should be encouraged.

The Many Faces of Metabolic Dysfunction-Associated Fatty Liver Disease Treatment: From the Mediterranean Diet to Fecal Microbiota Transplantation

The gastrointestinal tract is inhabited by the gut microbiota. The main phyla are Firmicutes and Bacteroidetes. In non-alcoholic fatty liver disease, now renamed metabolic dysfunction-associated fatty liver disease (MAFLD), an alteration in Firmicutes and Bacteroidetes abundance promotes its pathogenesis and evolution into non-alcoholic steatohepatitis, liver cirrhosis, and hepatocellular carcinoma. For this reason, early treatment is necessary to counteract its progression. The aim of the present narrative review is to evaluate the different therapeutic approaches to MAFLD. The most important treatment for MAFLD is lifestyle changes. In this regard, the Mediterranean diet could be considered the gold standard in the prevention and treatment of MAFLD. In contrast, a Western diet should be discouraged. Probiotics and fecal microbiota transplantation seem to be valid, safe, and effective alternatives for MAFLD treatment. However, more studies with a longer follow-up and with a larger cohort of patients are needed to underline the more effective approaches to contrasting MAFLD.

Association Between Metabolic Dysfunction-Associated Fatty Liver Disease and MACCEs in Patients with Diabetic Foot Ulcers: An Ambispective Longitudinal Cohort Study

Aim

Metabolic dysfunction-related fatty liver disease (MAFLD) is closely related to metabolic disorders. However, the relationship between MAFLD and the prognosis in diabetic foot ulcers (DFUs) remains unclear. This study aimed to explore the association between MAFLD and the risk of major adverse cardiac and cerebral events (MACCEs) in patients with DFUs.

Methods

889 inpatients with DFUs (PEDIS/TEXAS mild and above) were included in this study from 2013 to 2023. All participants were placed into non-MAFLD (n = 643) and MAFLD (n = 246) groups and followed up every 6 months for 10.9 years with a median of 63 months through in-person outpatient interviews and family fixed-line telephone visits. The association between MAFLD and the risk of MACCEs was evaluated through Multivariate Cox regression analyses, Stratified analyses and Kaplan-Meier survival analyses.

Results

Of the 889 subjects, 214 (24.07%) experienced MACCEs. Multivariate Cox regression analysis showed that MAFLD was independently associated with MACCEs (P < 0.001), of which with non-fatal myocardial infarction (P = 0.04), non-fatal stroke (P = 0.047), coronary artery revascularization (P = 0.002), heart failure (P = 0.029), and all-cause mortality (P = 0.021), respectively. The stratified analysis revealed that compared with non-MAFLD (HR=1), DFUs with MAFLD had a 2.64-fold increased risk for MACCEs (P <0.001; P for interaction = 0.001) in peripheral arterial disease (PAD) subgroup. Kaplan-Meier analysis evidenced that the MAFLD group had a higher cumulative incidence of MACCEs (log-rank, all P < 0.05).

Conclusion

MAFLD is a high-risk factor for MACCEs in patients with DFUs. The findings will remind clinicians to pay more attention to MAFLD in patients with DFUs, especially in patients with DFUs combined with PAD as early as possible in clinical practice and adopt timely effective intervention strategies to prevent the occurrence of MACCEs to improve the clinical prognosis in patients with DFUs.

The Metabolic Syndrome, a Human Disease

This review focuses on the question of metabolic syndrome (MS) being a complex, but essentially monophyletic, galaxy of associated diseases/disorders, or just a syndrome of related but rather independent pathologies. The human nature of MS (its exceptionality in Nature and its close interdependence with human action and evolution) is presented and discussed. The text also describes the close interdependence of its components, with special emphasis on the description of their interrelations (including their syndromic development and recruitment), as well as their consequences upon energy handling and partition. The main theories on MS's origin and development are presented in relation to hepatic steatosis, type 2 diabetes, and obesity, but encompass most of the MS components described so far. The differential effects of sex and its biological consequences are considered under the light of human social needs and evolution, which are also directly related to MS epidemiology, severity, and relations with senescence. The triggering and maintenance factors of MS are discussed, with especial emphasis on inflammation, a complex process affecting different levels of organization and which is a critical element for MS development. Inflammation is also related to the operation of connective tissue (including the adipose organ) and the widely studied and acknowledged influence of diet. The role of diet composition, including the transcendence of the anaplerotic maintenance of the Krebs cycle from dietary amino acid supply (and its timing), is developed in the context of testosterone and β-estradiol control of the insulin-glycaemia hepatic core system of carbohydrate-triacylglycerol energy handling. The high probability of MS acting as a unique complex biological control system (essentially monophyletic) is presented, together with additional perspectives/considerations on the treatment of this 'very' human disease.

The impact of piperine on the metabolic conditions of patients with NAFLD and early cirrhosis: a randomized double-blind controlled trial

Non-alcoholic fatty liver disease (NAFLD) is a metabolic dysfunction of the liver defined as an abnormal accumulation of fat within the liver without secondary triggers like alcohol consumption or viral hepatitis. Piperine, the bio-active ingredient of black pepper, can exert a significant function in treatment of individuals with NAFLDand early cirrhosis. We investigated the impact of piperine consumption with a duration of 12 weeks on patients with NAFLD and early cirrhosis compared toplacebo consumption. In a double-blind study, patients with NAFLD and early stage of cirrhosis were haphazardly distributed into case and control groups. They were prescribed a placebo and 5 mg of piperine for 12 weeks, respectively. The demographic and laboratory parameters of individuals were assessed as the baseline and after the duration of piperine intake. Piperine with a daily dosage of 5 mg could significantly decrease hepatic enzymes and glucose, and alleviate dyslipidemia in the case arm rather than the control arm. Moreover, HOMA levels and insulin resistance were reduced in case participants compared to the control counterparts. In the absence of approved medicinal intervention for patients with NAFLD, and regarding the favorable impact of piperine on NAFLD more studies on this subject are warranted.

B. longum CKD1 enhances the efficacy of anti-diabetic medicines through upregulation of IL- 22 response in type 2 diabetic mice

The gut microbiota plays a pivotal role in metabolic disorders, notably type 2 diabetes mellitus (T2DM). In this study, we investigated the synergistic potential of combining the effects of Bifidobacterium longum NBM7-1 (CKD1) with anti-diabetic medicines, LobeglitazoneⓇ (LO), SitagliptinⓇ (SI), and MetforminⓇ (Met), to alleviate hyperglycemia in a diabetic mouse model. CKD1 effectively mitigated insulin resistance, hepatic steatosis, and enhanced pancreatic β-cell function, as well as fortifying gut-tight junction integrity. In the same way, SI-CKD1 and Met- CKD1 synergistically improved insulin sensitivity and prevented hepatic steatosis, as evidenced by the modulation of key genes associated with insulin signaling, β-oxidation, gluconeogenesis, adipogenesis, and inflammation by qRT-PCR. The comprehensive impact on modulating gut microbiota composition was observed, particularly when combined with MetforminⓇ. This combination induced an increase in the abundance of Rikenellaceae and Alistipes related negatively to the T2DM incidence while reducing the causative species of Cryptosporangium, Staphylococcaceae, and Muribaculaceae. These alterations intervene in gut microbiota metabolites to modulate the level of butyrate, indole-3-acetic acid, propionate, and inflammatory cytokines and to activate the IL-22 pathway. However, it is meaningful that the combination of B. longum NBM7-1(CKD1) reduced the medicines' dose to the level of the maximal inhibitory concentrations (IC50). This study advances our understanding of the intricate relationship between gut microbiota and metabolic disorders. We expect this study to contribute to developing a prospective therapeutic strategy modulating the gut microbiota.

Dysmetabolic comorbidities and non-alcoholic fatty liver disease: a stairway to metabolic dysfunction-associated steatotic liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. This term does not describe the pathogenetic mechanisms and complications associated with NAFLD. The new definition, Metabolic Dysfunction-associated Steatotic Liver disease (MASLD), emphasizes the relationship between NAFLD and cardiometabolic comorbidities. Cardiovascular disease features, such as arterial hypertension and atherosclerosis, are frequently associated with patients with MASLD. Furthermore, these patients have a high risk of developing neoplastic diseases, primarily hepatocellular carcinoma, but also extrahepatic tumors, such as esophageal, gastric, and pancreatic cancers. Moreover, several studies showed the correlation between MASLD and endocrine disease. The imbalance of the gut microbiota, systemic inflammation, obesity, and insulin resistance play a key role in the development of these complications. This narrative review aims to clarify the evolution from NAFLD to the new nomenclature MASLD and evaluate its complications.

Exploring factors related to clinically advanced fibrosis in patients with nonalcoholic fatty liver disease or nonalcoholic steatohepatitis

OBJECTIVES

To describe the clinical profile of nonalcoholic fatty liver disease (NAFLD) or nonalcoholic steatohepatitis (NASH) patients in a Texas integrated delivery network (IDN) and elucidate the local relationship between patient factors and the risk of advanced fibrosis.

METHODS

This observational, retrospective, cross-sectional study utilized existing data from the electronic health record at a large Texas IDN. Data was collected during the study period from 1 January 2019, to 1 March 2023. Patient characteristics, comorbidities, labs, and medication orders were collected from the most recent encounter in which a Fibrosis-4 (FIB-4) score could be calculated. Chi square tests and analysis of variance (ANOVA) tests were conducted to evaluate differences among the three fibrosis risk categories. Ordinal logistic regression was utilized to assess associations between select variables and a higher risk of advanced fibrosis.

RESULTS

A total of 56,253 patients were included in the study. 34,839 (61.9%) were Low-Risk 15,578 (27.7%) were Intermediate-Risk, and 5,836 (10.4%) were High-Risk of advanced fibrosis. Results showed that up to 70.4% of patients within a risk group were obese. Only 49.5% of patients in the High-Risk group had at least one gastroenterologist or hepatologist visit. Males, Medicare patients, former smokers, and those with hypertension, type 2 diabetes, and chronic kidney disease were associated with a higher risk of advanced fibrosis.

CONCLUSION

This study highlights the need for early screening and proactive management of metabolic risk factors for patients with NAFLD/NASH. The findings indicate a notable prevalence of obesity in the study population, a need for specialist referral for those at High-Risk of advanced fibrosis, and the importance of routine labs to evaluate metabolic factors. Primary care providers may be ideal providers to target these interventions and address this care need.

Non-alcoholic fatty liver disease and gut microbial dysbiosis- underlying mechanisms and gut microbiota mediated treatment strategies

Non-alcoholic fatty liver disease (NAFLD) is by far the most prevalent form of liver disease worldwide. It's also the leading cause of liver-related hospitalizations and deaths. Furthermore, there is a link between obesity and NAFLD risk. A projected 25% of the world's population grieves from NAFLD, making it the most common chronic liver disorder. Several factors, such as obesity, oxidative stress, and insulin resistance, typically accompany NAFLD. Weight loss, lipid-lowering agents, thiazolidinediones, and metformin help prominently control NAFLD. Interestingly, pre-clinical studies demonstrate gut microbiota's potential causal role in NAFLD. Increased intestinal permeability and unhindered transport of microbial metabolites into the liver are the major disruptions due to gut microbiome dysbiosis, contributing to the development of NAFLD by dysregulating the gut-liver axis. Hence, altering the pathogenic bacterial population using probiotics, prebiotics, synbiotics, and fecal microbiota transplantation (FMT) could benefit patients with NAFLD. Therefore, it is crucial to acknowledge the importance of microbiota-mediated therapeutic approaches for NAFLD and comprehend the underlying mechanisms that establish a connection between NAFLD and gut microbiota. This review provides a comprehensive overview of the affiliation between dysbiosis of gut microbiota and the progress of NAFLD, as well as the potential benefits of prebiotic, probiotic, synbiotic supplementation, and FMT in obese individuals with NAFLD.

Does the Human Gut Virome Contribute to Host Health or Disease?

The human gastrointestinal (GI) tract harbors eukaryotic and prokaryotic viruses and their genomes, metabolites, and proteins, collectively known as the "gut virome". This complex community of viruses colonizing the enteric mucosa is pivotal in regulating host immunity. The mechanisms involved in cross communication between mucosal immunity and the gut virome, as well as their relationship in health and disease, remain largely unknown. Herein, we review the literature on the human gut virome's composition and evolution and the interplay between the gut virome and enteric mucosal immunity and their molecular mechanisms. Our review suggests that future research efforts should focus on unraveling the mechanisms of gut viruses in human homeostasis and pathophysiology and on developing virus-prompted precision therapies.

Ultrasound Prevalence and Clinical Features of Nonalcoholic Fatty Liver Disease in Patients with Inflammatory Bowel Diseases: A Real-Life Cross-Sectional Study

Background and Objectives: Inflammatory bowel disease (IBD) is a condition characterized by chronic intestinal inflammation. We can identify two major forms: Crohn's disease (CD) and ulcerative colitis (UC). One of the extraintestinal manifestations of IBD is nonalcoholic fatty liver disease (NAFLD). IBD and NAFLD share common pathogenetic mechanisms. Ultrasound (US) examination is the most commonly used imaging method for the diagnosis of NAFLD. This cross-sectional observational retrospective study aimed to evaluate the US prevalence of NAFLD in IBD patients and their clinical features. Materials and Methods: A total of 143 patients with IBD underwent hepatic US and were divided into two different groups according to the presence or absence of NAFLD. Subsequently, new exclusion criteria for dysmetabolic comorbidities (defined as plus) were applied. Results: The US prevalence of NAFLD was 23% (21% in CD and 24% in UC, respectively). Most IBD-NAFLD patients were male and older and showed significantly higher values for body mass index, waist circumference, disease duration, and age at onset than those without NAFLD. IBD-NAFLD patients showed a significantly higher percentage of stenosing phenotype and left-side colitis. Regarding metabolic features, IBD-NAFLD patients showed a significantly higher percentage of hypertension and IBD plus dysmetabolic criteria. Also, higher values of alanine aminotransferase and triglycerides and lower levels of high-density lipoproteins are reported in these patients. Conclusions: We suggest performing liver US screening in subjects affected by IBD to detect NAFLD earlier. Also, patients with NAFLD present several metabolic comorbidities that would fall within the new definition of metabolic-associated fatty liver disease. Finally, we encourage larger longitudinal studies, including healthy controls, to provide further confirmation of our preliminary data.

Potential impact of trained innate immunity on the pathophysiology of metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) occurs in a low-grade inflammatory milieu dependent on highly complex networks that span well-beyond the hepatic tissue injury. Dysfunctional systemic metabolism that characterizes the disease, is further induced in response to environmental cues that modify energy and metabolic cellular demands, thereby altering the availability of specific substrates that profoundly regulate, through epigenetic mechanisms, the phenotypic heterogeneity of immune cells and influence hematopoietic stem cell differentiation fate. This immuno-metabolic signaling drives the initiation of downstream effector pathways and results in the decompensation of hepatic homeostasis that precedes pro-fibrotic events. Recent evidence suggests that innate immune cells reside in different tissues in a memory effector state, a phenomenon termed trained immunity, that may be activated by subsequent exogenous (e.g., microbial, dietary) or endogenous (e.g., metabolic, apoptotic) stmuli. This process leads to long-term modifications in the epigenetic landscape that ultimately precondition the cells towards enhanced transcription of inflammatory mediators that accelerates MAFLD development and/or progression. In this mini review we aimed to present current evidence on the potential impact of trained immunity on the pathophysiology of MAFLD, shedding light on the complex immunobiology of the disease and providing novel potential therapeutic strategies to restrain the burden of the disease.

Gut Microbiota and Liver Transplantation: Immune Mechanisms behind the Rejection

Liver transplantation (LT) is the treatment of choice for patients with cirrhosis, decompensated disease, acute liver failure, and hepatocellular carcinoma (HCC). In 3-25% of cases, an alarming problem is acute and chronic cellular rejection after LT, and this event can lead to the need for new transplantation or the death of the patient. On the other hand, gut microbiota is involved in several mechanisms sustaining the model of the "gut-liver axis". These include modulation of the immune response, which is altered in case of gut dysbiosis, possibly resulting in acute graft rejection. Some studies have evaluated the composition of the gut microbiota in cirrhotic patients before and after LT, but few of them have assessed its impact on liver rejection. This review underlines the changes in gut microbiota composition before and after liver transplantation, hypothesizing possible immune mechanisms linking dysbiosis to transplantation rejection. Evaluation of changes in the gut microbiota composition in these patients is therefore essential in order to monitor the success of LT and eventually adopt appropriate preventive measures.

The Role of Gut Microbiota in the Clinical Outcome of Septic Patients: State of the Art and Future Perspectives

Sepsis is a life-threatening multiple-organ dysfunction caused by a dysregulated host response to infection, with high mortality worldwide; 11 million deaths per year are attributable to sepsis in high-income countries. Several research groups have reported that septic patients display a dysbiotic gut microbiota, often related to high mortality. Based on current knowledge, in this narrative review, we revised original articles, clinical trials, and pilot studies to evaluate the beneficial effect of gut microbiota manipulation in clinical practice, starting from an early diagnosis of sepsis and an in-depth analysis of gut microbiota.