The Leaky Gut and Human Diseases: "Can't Fill the Cup if You Don't Plug the Holes First".

BACKGROUND: The gut barrier is a sophisticated and dynamic system that forms the frontline defense between the external environment and the body's internal milieu and includes various structural and functional components engaged not only in digestion and nutrient absorption but also in immune regulation and overall health maintenance. SUMMARY: When one or more components of the intestinal barrier lose their structure and escape their function, this may result in a leaky gut. Mounting evidence emphasizes the crucial role of the gut microbiome in preserving the integrity of the gut barrier and provides insights into the pathophysiological implications of conditions related to leaky gut in humans. Assessment of intestinal permeability has evolved from invasive techniques to noninvasive biomarkers, but challenges remain in achieving consensus about the best testing methods and their accuracy. Research on the modulation of gut permeability is just starting, and although no medical guidelines for the treatment of leaky gut syndrome are available, several treatment strategies are under investigation with promising results. KEY MESSAGES: This review discusses the composition of the intestinal barrier, the pathophysiology of the leaky gut and its implications on human health, the measurement of intestinal permeability, and the therapeutic strategies to restore gut barrier integrity.

Exploring the Link between Helicobacter pylori, Gastric Microbiota and Gastric Cancer.

Gastric cancer (GC) still represents one of the leading causes of cancer-related mortality and is a major public health issue worldwide. Understanding the etiopathogenetic mechanisms behind GC development holds immense potential to revolutionize patients' treatment and prognosis. Within the complex web of genetic predispositions and environmental factors, the connection between Helicobacter pylori (H. pylori) and gastric microbiota emerges as a focus of intense research investigation. According to the most recent hypotheses, H. pylori triggers inflammatory responses and molecular alterations in gastric mucosa, while non-Helicobacter microbiota modulates disease progression. In this review, we analyze the current state of the literature on the relationship between H. pylori and non-Helicobacter gastric microbiota in gastric carcinogenesis, highlighting the mechanisms by which microecological dysbiosis can contribute to the malignant transformation of the mucosa.

A holistic evaluation of patients with chronic Hepatitis D virus (HDV) infection enrolled in the Italian PITER-B and delta cohort.

BACKGROUND AND AIMS: We aimed to characterize the epidemiologic and comorbidities profiles of patients with chronic Hepatitis D (CHD) followed in clinical practice in Italy and explored their interferon (IFN) eligibility. METHODS: This was a cross-sectional study of the PITER cohort consisting of consecutive HBsAg-positive patients from 59 centers over the period 2019-2023. Multivariable analysis was performed by logistic regression model. RESULTS: Of 5492 HBsAg-positive enrolled patients, 4152 (75.6%) were screened for HDV, 422 (10.2%) were anti-HDV positive. Compared with HBsAg mono-infected, anti-HDV positive patients were more often younger, non-Italians, with a history of drug use, had elevated alanine transaminase (ALT), cirrhosis, or hepatocellular carcinoma (HCC). Compared with Italians, anti-HDV positive non-Italians were younger (42.2% age ≤ 40 years vs. 2.1%; P < 0.001), more often females (males 43.0% vs. 68.6%; P < 0.001) with less frequent cirrhosis and HCC. HDV-RNA was detected in 63.2% of anti-HDV-positive patients, who were more likely to have elevated ALT, cirrhosis, and HCC. Extrahepatic comorbidities were present in 47.4% of anti-HDV positive patients and could affect the eligibility of IFN-containing therapies in at least 53.0% of patients in care. CONCLUSIONS: CHD affects young, foreign-born patients and older Italians, of whom two-thirds had cirrhosis or HCC. Comorbidities were frequent in both Italians and non-Italians and impacted eligibility for IFN.

The professional background of a referring physician predicts the diagnostic yield of small bowel capsule endoscopy in suspected small bowel bleeding.

Background and study aims The diagnostic yield of small-bowel capsule endoscopy (SBCE) in suspected small bowel bleeding (SSBB) is highly variable. Different reimbursement systems and equipment costs also limit SBCE use in clinical practice. Thus, minimizing non-diagnostic procedures is advisable. This study aimed to assess the SBCE diagnostic yield and identify factors predicting diagnostic findings in a cohort of patients with SSBB. Patients and methods In this retrospective cohort study, we analyzed the medical records of patients who consecutively underwent SBCE for SSBB over 9 years. By logistic regression, we identified covariates predicting diagnostic findings at SBCE. Finally, we performed a post-hoc cost analysis based on previous gastroenterologist or endoscopist consultations versus direct SBCE ordering by other specialists. Results The final analysis included 584 patients. Most SBCEs were ordered by a gastroenterologist or endoscopist (74%). The number of SBCEs without any finding was significantly lower in the gastroenterologist/endoscopist group P <0.001). The SBCE diagnostic yield ordered by a gastroenterologist or endoscopist was significantly higher than that by other specialists (63% vs 52%, odds ratio [OR] 1.57; 95% confidence interval [CI] 1.07-2.26, P =0.019). At multivariate analysis, older age (OR 1.7, 95%CI 1.2-2.4, P =0.005), anemia (OR 4.9, 95%CI 1.9-12, P =0.001), small bowel transit time (OR 1, 95%CI 1-1.02, P =0.039), and referring physician (OR 1.8, 95%CI 1.1-2.7, P =0.003) independently predicted diagnostic findings. Implementing prior gastroenterologist or endoscopist referral vs direct SBCE ordering would reduce medical expenditures by 16%. Conclusions The professional background of referring physicians significantly improves the diagnostic yield of SBCE and contributes to controlling public health costs.

Autoimmune liver diseases and SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing coronavirus disease 2019 (COVID-19), can trigger autoimmunity in genetically predisposed individuals through hyperstimulation of immune response and molecular mimicry. Here we summarise the current knowledge about auto-immune liver diseases (AILDs) and SARS-CoV-2, focusing on: (1) The risk of SARS-CoV-2 infection and the course of COVID-19 in patients affected by AILDs; (2) the role of SARS-CoV-2 in inducing liver damage and triggering AILDs; and (3) the ability of vaccines against SARS-CoV-2 to induce autoimmune responses in the liver. Data derived from the literature suggest that patients with AILDs do not carry an increased risk of SARS-Cov-2 infection but may develop a more severe course of COVID-19 if on treatment with steroids or thiopurine. Although SARS-CoV-2 infection can lead to the development of several autoimmune diseases, few reports correlate it to the appearance of de novo manifestation of immune-mediated liver diseases such as autoimmune hepatitis (AIH), primary biliary cholangitis (PBC) or AIH/PBC overlap syndrome. Different case series of an AIH-like syndrome with a good prognosis after SARS-CoV-2 vaccination have been described. Although the causal link between SARS-CoV-2 vaccines and AIH cannot be definitively established, these reports suggest that this association could be more than coincidental.

Effectiveness of first and second-line empirical treatment in Italy: Results of the European registry on Helicobacter pylori management.

BACKGROUND AND AIMS: The optimal management of naïve and not naïve Helicobacter pylori patients remains unclear. Therefore, it is essential to evaluate whether the actual clinical practice mirrors the indications suggested by the guidelines. This study aimed to assess the effectiveness and the safety of the empirical first- and second-line treatments prescribed to patients enroled at Italian centres participating in the European Registry on H. pylori Management (Hp-EuReg). METHODS: The Hp-EuReg is an international multicentre prospective non-interventional registry starting in 2013 aiming to evaluate the management of H. pylori infection by European gastroenterologists. Patients were registered in an e-CRF by AEG-REDCap. Variables assessed included demographics, previous eradication attempts, treatment regimen, effectiveness, and tolerance. RESULTS: Overall, 3723 patients from 2013 to February 2021 were included: 2996 and 727 received an empirical first- and second-line treatment, respectively. According to the modified ITT analysis, among the first-line regimens, only the bismuth quadruple therapy with three-in-one-single capsule (BQT-TSC), the concomitant, and the sequential treatment - all lasting 10 days - achieved an eradication rate >90%. Among the second-line regimens, only the 10-day BQT-TSC reported an effectiveness >90%. High-dose PPI twice daily also significantly increased the effectiveness of some therapies. The BQT-TSC was the regimen with the highest incidence of adverse events. CONCLUSIONS: Only quadruple therapies lasting at least 10 days achieved over 90% eradication rates among the empirical first- and second-line regimens. It remains unclear whether high-dose PPI twice daily can improve the efficacy of quadruple treatment.

Probiotics in Gastrointestinal Diseases: All that Glitters Is Not Gold.

BACKGROUND: Multiple lines of evidence now support the notion that gut microbiota can contribute to digestive and extra-digestive diseases. The emergence of these observations enabled to postulate a bacteria-centric paradigm to rethink the treatment of many diseases. The goal of therapy should not be to eradicate the flora but to modify it in a way that leads to symptomatic improvement; thus, the interest in the use of probiotics to modulate microbiota composition has increased worldwide in both community and healthcare settings. SUMMARY: The results of published studies are conflicting for most probiotic strains and formulations, and clinicians and consumers need a better understanding of probiotic risks and benefits. Currently, clear guidelines on when to use probiotics and the most effective probiotic for different gastrointestinal conditions are still lacking. Here, we reviewed the studies on the use of probiotics in some diseases of relevant interest to gastroenterologists, such as Helicobacter pylori infection, irritable bowel syndrome, and inflammatory bowel disease. Key Message: Although the evidence is relevant and promising for probiotics in general, and for specific strains and combinations of strains, it is not yet sufficient to draw unequivocal conclusions and clear recommendations.

Gut Microbes and Hepatic Encephalopathy: From the Old Concepts to New Perspectives.

Hepatic encephalopathy (HE) is a severe complication of advanced liver disease and acute liver failure. The clinical spectrum ranges from minor cognitive dysfunctions to lethargy, depressed consciousness, and coma and significantly impact the quality of life, morbidity, and mortality of the patients. It is commonly accepted that the gut milieu is essential for the development of HE; however, despite intensive research efforts, the pathogenesis of HE is still not fully elucidated. As our knowledge of gut microbiota moves from the pioneering era of culture-dependent studies, the connection between microbes, inflammation, and metabolic pathways in the pathogenesis of HE is becoming increasingly clear, providing exciting therapeutic perspectives. This review will critically examine the latest research findings on the role of gut microbes in the pathophysiological pathways underlying HE. Moreover, currently available therapeutic options and novel treatment strategies are discussed.

Effectiveness and predictors of response to somatostatin analogues in patients with gastrointestinal angiodysplasias: a systematic review and individual patient data meta-analysis.

BACKGROUND: Gastrointestinal angiodysplasias are vascular malformations that often cause red blood cell transfusion-dependent anaemia. Several studies suggest that somatostatin analogues might decrease rebleeding rates, but the true effect size is unknown. We therefore aimed to investigate the efficacy of somatostatin analogues on red blood cell transfusion requirements of patients with gastrointestinal angiodysplasias and to identify subgroups that might benefit the most from somatostatin analogue therapy. METHODS: We did a systematic review and individual patient data meta-analysis. We searched MEDLINE, Embase, and Cochrane on Jan 15, 2016, with an updated search on April 25, 2021. All published randomised controlled trials and cohort studies that reported on somatostatin analogue therapy in patients with gastrointestinal angiodysplasias were eligible for screening. We excluded studies without original patient data, single case reports, small case series (ie, <10 participants), studies in which patients had a specific aetiology of gastrointestinal angiodysplasias, and studies in which somatostatin analogue therapy was initiated simultaneously with other treatment modalities. Authors of eligible studies were invited to share individual patient data. Aggregated data was used if individual patient data were not provided. The primary outcome was the mean reduction in the number of red blood cell transfusions during somatostatin analogue therapy, compared with baseline, expressed as the incidence rate ratio (IRR) and absolute mean decrease. We defined patients as either good responders (≥50% reduction in the number of red blood cell transfusions) or poor responders (<50% reduction). A mixed-effects negative binomial regression was used to account for clustering of patients and skewness in data. This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO), number CRD42020213985. FINDINGS: We identified 11 eligible studies (one randomised controlled trial and ten cohort studies) of moderate-to-high quality and obtained individual patient data from the authors of nine (82%) studies. The remaining two (18%) studies provided sufficient information in the published manuscript to extract individual patient data. In total, we analysed data from 212 patients. Somatostatin analogues reduced the number of red blood cell transfusions with an IRR of 0·18 (95% CI 0·14-0·24; p<0·0001) during a median treatment duration of 12 months (IQR 6·0-12·0) and follow-up period of 12 months (12·0-12·0), correlating with a mean absolute decrease in the number of red blood cell transfusions from 12·8 (95% CI 10·4-15·8) during baseline to 2·3 (1·9-2·9) during follow-up-ie, a reduction of 10·5 red blood cell transfusions (p<0·0001). 177 (83%) of 212 patients had a good response to somatostatin analogue therapy (defined as at least a 50% reduction in the number of red blood cell transfusions). Heterogeneity across studies was moderate (I2=53%; p=0·02). Location of gastrointestinal angiodysplasias in the stomach compared with angiodysplasias in the small bowel and colon (IRR interaction 1·92 [95% CI 1·13-3·26]; p=0·02) was associated with worse treatment response. Octreotide was associated with a better treatment response than lanreotide therapy (IRR interaction 2·13 [95% CI 1·12-4·04]; p=0·02). The certainty of evidence was high for the randomised controlled trial and low for the ten cohort studies. Adverse events occurred in 38 (18%) of 212 patients receiving somatostatin analogue therapy, with ten (5%) discontinuing this therapy because of adverse events. The most common adverse events were loose stools (seven [3%] of 212), cholelithiasis (five [2%]), flatulence (four [2%]), and administration site reactions (erythema, five [2%]). INTERPRETATION: Somatostatin analogue therapy is safe and effective in most patients with red blood cell transfusion-dependent bleeding due to gastrointestinal angiodysplasias. Somatostatin analogue therapy is more effective in patients with angiodysplasias located in the small bowel and colon, and octreotide therapy seems to be more effective than lanreotide therapy. FUNDING: The Netherlands Organisation for Health Research and Development and the Radboud University Medical Center.

Blinded Oral Challenges with Lactose and Placebo Accurately Diagnose Lactose Intolerance: A Real-Life Study.

Lactose intolerance (LI) is characterized by diarrhea, abdominal pain, or bloating occurring after lactose consumption in patients with lactose malabsorption. The National Institute of Health (NIH) proposed a double-blind placebo testing to identify LI individuals correctly. However, until now, no study used this approach in a real-life setting. We aimed to assess double-blind placebo challenge accuracy in diagnosing LI in patients with self-reported symptoms of LI. 148 patients with self-reported LI were consecutively enrolled and blindly underwent hydrogen breath test (HBT) after 25 g lactose or 1 g glucose (placebo) load. One week later, the subjects were challenged with the alternative substrate. Each subject completed a validated questionnaire, including five symptoms (diarrhea, abdominal pain, vomiting, bowel sounds, and bloating) scored on a 10-cm visual analog scale. Home questionnaire (HQ) referred to symptoms associated with the consumption of dairy products at home, while lactose questionnaire (LQ) and placebo questionnaire (PQ) referred to symptoms perceived throughout the 4-h after the administration of the substrates, respectively. After lactose load, HBT was positive in 81 patients (55%), of whom 60 (74%) reported relevant symptoms at LQ (lactose malabsorbers, LM). After placebo challenge, 45 out of 60 with a positive lactose challenge did not complain of symptoms and therefore were diagnosed as lactose intolerant, according to NIH definition. The blinded oral challenges with lactose and placebo accurately diagnose LI and identify patients who will likely benefit from a lactose-free diet.

Lactose Intolerance Assessed by Analysis of Genetic Polymorphism, Breath Test and Symptoms in Patients with Inflammatory Bowel Disease.

Many patients with inflammatory bowel disease (IBD) restrict dairy products to control their symptoms. The aim of the study was to investigate the prevalence of lactose intolerance assessed with hydrogen breath test (H-BT) in IBD patients in clinical remission compared to a sex, age and BMI matched control population. We further detected the prevalence of three single nucleotide polymorphisms of the lactase (LCT) gene: the lactase non persistence LCT-13910 CC (wildtype) and the intermediate phenotype LCT-22018 CT and LCT-13910 AG; finally, we assess the correlation between genotype and H-BT. A total of 54 IBD patients and 69 control who underwent clinical evaluation, H-BT and genetic test were enrolled. H-BT was positive in 64.8% IBD patients and 62.3% control (p = 0.3). The wild-type genotype was found in 85.2% IBD patients while CT-22018, AG-13910 and CT-22018/AG-13910 polymorphisms were found in 9.3%, 1.8% and 3.7%. In the control group, the wild-type genotype, CT-22018, AG-13910 and CT-22018/AG-13910 polymorphisms were found in 87%, 5.8%, 5.8% and 1.4% of cases, respectively. Therefore, the wild-type and polymorphisms' prevalence did not differ between IBD population and control group (85.2% vs. 87%, p = 0.1) (14.8% vs. 13%, p = 0.7). The correlation between positive H-BT and genetic analysis showed that the wild-type genotype was associated with higher rate of lactose intolerance in the total population (OR 5.31, 95%CI 1.73-16.29, p = 0.003) and in the IBD (OR 7.61, 95%CI 1.36-42.7, p = 0.02). The prevalence of lactose intolerance in IBD patients did not differ from that of control. Despite suggestive symptoms, about 1/3 of IBD patients are not lactose intolerant, thus not needing "a priori" elimination diet. This may encourage a rationale and balanced dietary management in IBD.

Bone Marrow of Contention: A Rare Case of Recurrent Acute Hepatitis.

Hepatitis-associated aplastic anemia is a well-recognized clinical syndrome in which marrow failure follows the development of hepatitis. Although aplastic anemia is intimately related to paroxysmal nocturnal hemoglobinuria, until now, no cases of PNH-associated hepatitis have been described. We report a case of recurrent acute hepatitis preceding the clinical onset of PNH. Treatment of PNH with the complement inhibitor eculizumab (Soliris®) prevented both recurrences of episodes of intravascular hemolysis and liver enzyme alteration. This is the first known published case of PNH-associated hepatitis.

Impact of proton pump inhibitors on cytochrome P450 activity assessed by 13 C-aminopyrine breath test in patients with cirrhosis.

BACKGROUND: Chronic use of proton pump inhibitors (PPIs) in patients with impaired liver function may worsen cytochrome P450 (CYP450) activity, predisposing them to clinically relevant drug-drug interactions. The 13 C-aminopyrine breath test (13 C-ABT) is a non-invasive tool to study CYP450-dependent liver function. AIMS: To assess 13 C-ABT modifications with different PPIs in patients with cirrhosis METHODS: Sixty consecutive patients with HCV-related cirrhosis and indication to start PPI therapy were randomised to receive omeprazole 20 mg/day, esomeprazole 20 mg/day, lansoprazole 15 mg/day, pantoprazole 40 mg/day or rabeprazole 20 mg/day. 13 C-ABT was performed at baseline and on the 15th day of PPI therapy. RESULTS: At baseline, mean values of max 13 C% dose/h and 13 C% cum dose at 120 minutes did not differ significantly among groups. On the 15th day of therapy, max 13 C% dose/h and 13 C% cum dose at 120 minutes did not significantly differ with respect to baseline for pantoprazole (P = 0.184 and P = 0.309, respectively) or rabeprazole (P = 0.536 and P = 0.286, respectively), but were significantly decreased on omeprazole (P = 0.013 and P = 0.015, respectively), esomeprazole (P = 0.009 and P = 0.001, respectively), and lansoprazole (P = 0.033 and P = 0.035, respectively). CONCLUSIONS: In patients with cirrhosis, omeprazole, esomeprazole and lansoprazole inhibit microsomal activity while pantoprazole and rabeprazole do not have a significant impact. Should our data be confirmed in larger cohort studies, pantoprazole and rabeprazole could be safely recommended for patients with cirrhosis.

Pharmacological treatment of gastrointestinal bleeding due to angiodysplasias: A position paper of the Italian Society of Gastroenterology (SIGE).

Angioectasias (AD) belong to benign vascular malformations of the gastrointestinal tract and are responsible for about 4-7% of upper non variceal bleeding, 30-40% of small bowel occult bleeding and 3-40% of colonic bleeding episodes. Gastrointestinal haemorrhage secondary to AD represents an important diagnostic and therapeutic problem that negatively impacts on the quality of life of patients and heath care costs. Endoscopic interventions are the mainstay in both diagnosis and treatment of vascular malformations. However, in a substantial percentage of the cases, age of the patients, comorbidities, clinical severity of anaemia and blood loss as well as size, site and number of lesions prevent this therapeutic approach. Hormonal therapy, thalidomide and somatostatin analogues have been investigated for their potential role as rescue therapies in controlling AD bleeding although, thus far, no recommendations have been provided on their use in this clinical setting. In order to implement appropriate prescription of pharmacological agents to manage gastrointestinal bleeding due to ADs, the Italian Society of Gastroenterology (SIGE) nominated a panel of experts who reviewed the available clinical literature and produced practical clinical recommendations.

Gastric Emptying Impacts the Timing of Meal Glucose Peak in Subjects With Uncomplicated Type 1 Diabetes.

Context: Diabetes mellitus is associated with gastrointestinal (GI) motility dysfunction, ranging from delayed to accelerated gastric emptying (GE). Objective: To evaluate GE in patients with type 1 diabetes mellitus (T1DM) without chronic complications and to investigate its relation with postprandial glucose and GI hormone responses. Design: Cross-sectional study. Setting/Participants: Forty-two patients with T1DM free of chronic complications referred to Federico II University and 31 healthy controls similar for age, sex, and body mass index. Interventions/Main Outcome Measures: GE was assessed by using the 13C-octanoate breath test with a standardized solid meal. During the meal, plasma glucose, ghrelin, and glucagon-like peptide 1 (GLP-1) responses were assessed, and GI symptoms were evaluated by a specific questionnaire. Results: Patients with T1DM showed a significantly slower GE half-emptying time (GE t1/2) (113 ± 34 minutes) than did controls (89 ± 17 minutes; P < 0.001). Thirty-six percent of T1DM showed a delayed GE (t1/2 > 120 minutes), whereas all controls showed a normal GE. When patients with T1DM were stratified according to GE t1/2, postmeal glucose response was significantly different between those with delayed and those with normal GE (P = 0.013). In particular, patients with T1DM and delayed GE showed a significantly longer mean time to peak glucose than did patients with normal GE (P = 0.004). In addition, GE t1/2 was an independent predictor of the time to peak glucose (ß = 0.329; P = 0.025). GLP-1 and ghrelin responses to the test meal, as well as the prevalence of GI symptoms, were similar between patients with T1DM and controls and between patients with T1DM with normal GE and those with delayed GE. Conclusions: Delayed GE time is associated with a longer time to peak glucose. GE evaluation could be useful for individualizing the timing of preprandial insulin bolus in patients with T1DM.

Gastric Emptying Time, Esophageal pH-Impedance Parameters, Quality of Life, and Gastrointestinal Comorbidity in Obese Children and Adolescents.

OBJECTIVES: To provide further evidence regarding the relationship between obesity and gastroesophageal reflux disease (GERD) in children, through the use of 13C-octanoic acid breath test for gastric emptying time (GET) assessment and esophageal multichannel intraluminal impedance pH-testing (MII-pH). STUDY DESIGN: Obese children aged 4-17 years completed a questionnaire investigating reflux symptoms, the presence of functional gastrointestinal disorders, and quality of life. A subgroup of obese patients with and without GERD symptoms were asked to undergo 13C-octanoic acid breath test. Symptomatic patients were also required to undergo MII-pH. Age- and sex- matched asymptomatic nonobese children were enrolled as a comparison group. RESULTS: Of 113 enrolled patients, 44 (38.9%) reported reflux symptoms; 22 of the 44 underwent MII-pH. Their mean reflux index was 14.6%, and their mean number of daily reflux episodes was 51.8. The mean T½ GET of symptomatic was 107.6 minutes vs 116.5 minutes in asymptomatic obese children. Healthy nonobese children had a mean T½ GET of 100.1 minutes. The mean GET of symptomatic obese patients having >70 daily reflux events was 121.8 vs 87.6 minutes of patients with <70 daily reflux events (P <.05). Both symptomatic and asymptomatic obese patients had a worse quality of life than nonobese (P = 0.003 and P = 0.0002, respectively); a narrow waist circumference was directly related to GET (P = 0.01). CONCLUSIONS: A high percentage of obese children and adolescents experience GERD symptoms. GET was directly related to the narrow waist circumference of obese children with GERD and was significantly delayed in obese children with increased reflux events. Both symptomatic and asymptomatic obese patients had a worse quality of life compared with nonobese healthy patients.

The gut microbiota: A new potential driving force in liver cirrhosis and hepatocellular carcinoma.

The gut microbiota has recently been recognized as a major environmental factor in the pathophysiology of many human diseases. The anatomical and function connection existing between gut and liver provides the theoretical basis to assume the liver is a major target for gut microbes. In the last decades, numerous studies reported an altered composition of gut microbiota in patients with liver cirrhosis and a progressively marked dysbiosis with worsening of the liver disease. The risk of developing hepatocellular carcinoma, the deadliest complication of liver cirrhosis, is widely variable among cirrhotic patients, thus suggesting a complexity of genetic and environmental factors implicated in hepatocarcinogenesis. Gut microbiota is now emerging as a plausible candidate to explain this variability. In this manuscript we review the human and the experimental evidence supporting the potential implication of gut microbiota in the promotion, progression and complication of liver disease.