Liver disease symptoms in non-alcoholic fatty liver disease and small intestinal bacterial overgrowth

Non-alcoholic fatty liver disease in irritable bowel syndrome: More than a coincidence?

Irritable bowel syndrome (IBS) and non-alcoholic fatty liver disease (NAFLD) are amongst the most common gastrointestinal and liver conditions encountered in primary and secondary care. Recently, there has been interest in the apparent co-incidence of NAFLD in patients with IBS mainly driven by improved understanding of their shared risk factors and pathophysiology. In this paper we summarize the shared risk factors which include; overlapping nutritional and dietary factors as well as shared putative mechanisms of pathophysiology. These include changes in the gut microbiome, gut permeability, immunity, small bowel bacterial overgrowth and bile acid metabolism. This paper describes how these shared risk factors and etiological factors may have practical clinical implications for these highly prevalent conditions. It also highlights some of the limitations of current epidemiological data relating to estimates of the overlapping prevalence of the two conditions which have resulted in inconsistent results and, therefore the need for further research. Early recognition and management of the overlap could potentially have impacts on treatment outcomes, compliance and morbidity of both conditions. Patients with known IBS who have abnormal liver function tests or significant risk factors for NAFLD should be investigated appropriately for this possibility. Similarly, IBS should be considered in patients with NAFLD and symptoms of abdominal pain associated with defecation, an altered bowel habit and bloating.

Gut microbiota and their metabolites in the progression of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent liver disorder worldwide. It comprises a spectrum of conditions that range from steatosis to non-alcoholic steatohepatitis, with progression to cirrhosis and hepatocellular carcinoma. Currently, there is no FDA-approved pharmacological treatment for NAFLD. The pathogenesis of NAFLD involves genetic and environmental/host factors, including those that cause changes in intestinal microbiota and their metabolites. In this review, we discuss recent findings on the relationship(s) of microbiota signature with severity of NAFLD and the role(s) microbial metabolites in NAFLD progression. We discuss how metabolites may affect NAFLD progression and their potential to serve as biomarkers for NAFLD diagnosis or therapeutic targets for disease management.

Association of worsening of nonalcoholic fatty liver disease with cardiometabolic function and intestinal bacterial overgrowth: A cross-sectional study

Background & aims

Non-alcoholic fatty liver disease (NAFLD) has been associated with small bowel bacterial overgrowth (SIBO) and cardiometabolic dysfunction. This cross-sectional study aimed to evaluate the cardio-metabolic parameters and SIBO in patients with different degrees of hepatic fibrosis estimated by NAFLD fibrosis score (NFS).

Methods

Subjects (n = 78) were allocated to three groups: Healthy control (n = 30), NAFLD with low risk of advanced fibrosis (NAFLD-LRAF, n = 17) and NAFLD with a high risk of advanced fibrosis (NAFLD-HRAF, n = 31). Anthropometrics, blood pressure, electrocardiogram and heart rate variability (HRV) were evaluated. Only the NAFLD-LRAF and NAFLD-HRAF groups were submitted to blood biochemical analysis and glucose hydrogen breath tests.

Results

The NAFLD-HRAF group had higher age and body mass index when compared to the control and NAFLD-LRAF groups. The prevalence of SIBO in the NAFLD group was 8.33%. The low frequency/high-frequency ratio (LF/HF ratio) was augmented in NAFLD-LRAF (p < 0.05) when compared with control group. NAFLD-HRAF group had a wide QRS complex (p < 0.05) and reduced LF/HF ratio (p < 0.05) compared to the control and NAFLD-LRAF groups. Serum levels of albumin and platelets were more reduced in the NAFLD-HRAF subjects (p < 0.05) than in the NAFLD-LRAF.

Conclusions

NAFLD impairs cardiac autonomic function. Greater impairment was found in subjects with a worse degree of hepatic fibrosis estimated by NFS. Hypoalbuminemia and thrombocytopenia were higher in subjects with a worse degree of hepatic fibrosis, whereas prevalence of SIBO positive was similar between the groups.

Randomised Double-Blind Placebo-Controlled Trial of Inulin with Metronidazole in Non-Alcoholic Fatty Liver Disease (NAFLD)

Background: Non-alcoholic fatty liver disease (NAFLD) can be ameliorated by weight loss although difficult to maintain. Emerging evidence indicates that prebiotics and antibiotics improve NAFLD. Aim: To determine whether inulin supplementation after brief metronidazole therapy is effective in reducing alanine aminotransferase (ALT) and maintaining weight loss achieved through a very-low-calorie diet (VLCD) among people with NAFLD. Methods: Sixty-two people with NAFLD commenced 4-week VLCD using Optifast meal replacements (600 kcal/day). Sixty were then randomised into a 12-week double-blind, placebo-controlled, parallel three-arm trial: (1) 400 mg metronidazole twice daily in Week 1 then inulin 4 g twice daily OR (2) placebo twice daily in week one then inulin OR (3) placebo-placebo. Main outcomes were ALT and body weight at 12 weeks. Fecal microbiota changes were also evaluated. Results: Mean body mass index (BMI) and ALT reduced after VLCD by 2.4 kg/m² and 11 U/L, respectively. ALT further decreased after metronidazole-inulin compared to after placebo-placebo (mean ALT change -19.6 vs. -0.2 U/L, respectively; p = 0.026); however, weight loss maintenance did not differ. VLCD treatment decreased the ratio of Firmicutes/Bacteroidetes (p = 0.002). Conclusion: Brief metronidazole followed by inulin supplementation can reduce ALT beyond that achieved after VLCD in patients with NAFLD.

Role and effective therapeutic target of gut microbiota in NAFLD/NASH

Non-alcoholic fatty liver disease (NAFLD), the most prevalent chronic liver disease in the world, is affected by numerous extrinsic and intrinsic factors, including lifestyle, environment, diet, genetic susceptibility, metabolic syndrome and gut microbiota. Accumulating evidence has proven that gut dysbiosis is significantly associated with the development and progression of NAFLD, and several highly variable species in gut microbiota have been identified. The gut microbiota contributes to NAFLD by abnormal regulation of the liver-gut axis, gut microbial components and microbial metabolites, and affects the secretion of bile acids. Due to the key role of the gut microbiota in NAFLD, it has been regarded as a potential target for the pharmacological and clinical treatment of NAFLD. The present review provides a systematic summary of the characterization of gut microbiota and the significant association between the gut microbiota and NAFLD. The possible mechanisms of how the gut microbiota is involved in promoting the development and progression of NAFLD were also discussed. In addition, the potential therapeutic methods for NAFLD based on the gut microbiota were summarized.

The role of Small Intestinal Bacterial Overgrowth (SIBO) in Non-alcoholic Fatty Liver Disease (NAFLD) patients evaluated using Controlled Attenuation Parameter (CAP) Transient Elastography (TE): a tertiary referral center experience

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is an emerging disease, where it can progress to non-alcoholic steatohepatitis (NASH) and lead to liver cirrhosis or liver cancer. Small intestinal bacterial overgrowth (SIBO) has been hypothesized to play an important role in NAFLD development and progression, however, there is still conflicting data about this phenomenon. Transient Elastography (TE) examination using controlled attenuation parameter (CAP) has been validated for liver disease progression assessment in NAFLD. It is non-invasive method and easy to perform in clinical practice. Therefore, we would like to know the role of SIBO in NAFLD and its possible impact on disease progression.

METHODS

A cross-sectional design study performed at outpatient's Hepatobiliary clinic at tertiary referral university hospital in Jakarta. All recruited study subjects based on inclusions criteria underwent laboratory examination, transabdominal ultrasound examination, CAP-TE 502 (by Echosens, France), and glucose hydrogen breath test (GHBT) using portable hydrogen breath test apparatus (Gastro+™ Gastrolyzer by Bedfont Scientific Ltd). Stool sample examination was performed using RT-PCR.

RESULTS

This study recruited 160 subjects with median age of 58 (22-78) years and 108 (67.5%) of them are female. SIBO (65,5%), DM (70.8%), dyslipidemia (75.2%), obesity (76.6%), and metabolic syndrome (73%) were more prevalent in NAFLD than non-NAFLD population. Bivariate analysis showed no significant association between SIBO and NAFLD development (p = 0.191; PR 0.871; CI 95% [0.306-1.269]). SIBO was also not associated with significant hepatic steatosis (p = 0.951; PR = 0.951; CI 95% [0.452-2.239]) and fibrosis (p = 0.371; PR = 1.369; CI 95% [0.608-3.772]). However, the presence of central obesity has significantly associated with the presence of SIBO (p = 0.001; PR = 0.378; CI 95% [0.021-0.478]). Based on stool sample analysis from 60 NAFLD patients, there is a significant correlation using Spearmen test between the presence of Bacteroides and the stage of fibrosis (p .037). Further analysis between obese NAFLD patients and non-obese NAFLD patients showing that there is a significant decrease of Bifidobacteria (p .047) and Lactobacillus (p .038) in obese NAFLD patients and a tendency of increase Bacteroides in obese NAFLD patients (p .572).

CONCLUSIONS

SIBO is not associated with NAFLD development and progression.

The role of gut microbiota in liver disease development and treatment

Liver cancer is the sixth most common cancer worldwide, and the third most common cause of cancer-related death. Hepatocellular carcinoma (HCC), which accounts for more than 90% of primary liver cancers, is an important public health problem. In addition to cirrhosis caused by hepatitis B viral (HBV) or hepatitis C viral (HCV) infection, non-alcoholic fatty liver disease (NAFLD) is becoming a major risk factor for liver cancer because of the prevalence of obesity. Non-alcoholic steatohepatitis (NASH) will likely become the leading indication for liver transplantation in the future. It is well recognized that gut microbiota is a key environmental factor in the pathogenesis of liver disease and cancer. The interplay between gut microbiota and liver disease has been investigated in animal and clinical studies. In this article, we summarize the roles of gut microbiota in the development of liver disease as well as gut microbiota-targeted therapies.

Small intestinal bacterial overgrowth and nonalcoholic fatty liver disease

The gut microbiota has recently been recognized as a major environmental factor in the pathophysiology of several human diseases. The anatomical and functional association existing between the gut and the liver provides the theoretical basis to assume that the liver is a major target for gut microbes. In the last decades, many studies have reported an altered composition of gut microbiota in patients with chronic liver diseases and liver cirrhosis, suggesting a progressively marked dysbiosis to be related to worsening of the liver disease. Modifications of microbiota result in alteration in providing signals through the intestine and bacterial products, as well as hormones produced in the bowel that affect metabolism at different levels including the liver. There is increasing evidence for a correlation between intestinal microbiota, bacterial translocation and hepatic steatosis. Intestinal microbiota affects nutrient absorption and energy homeostasis. Altered intestinal permeability may favor the passage of bacteria derived compounds into the systemic circulation, causing a systemic inflammatory state, characteristic of the metabolic syndrome. At present, an increasing number of studies indicate a close relationship between dysbiosis, defined as abnormal composition and the amount of intestinal bacteria (gut microbiota), intestinal permeability and some metabolic, inflammatory, degenerative and even psychiatric diseases. Microbiota pharmacological modulation seems to be a promising tool for a new therapeutic approach to non-alcoholic fatty liver disease and in prevention of cirrhosis.

The following study aims to briefly discuss the role of microbiota disorder (dysbiosis), and in particular small intestinal bacterial overgrowth (SIBO), in the pathogenesis of nonalcoholic fatty liver disease (NAFLD).