Differences in Fecal Short-Chain Fatty Acids between Alcoholic Fatty Liver-Induced Cirrhosis and Non-alcoholic (Metabolic-Associated) Fatty Liver-Induced Cirrhosis

Does Timing of Ileal Pouch-Anal Anastomosis Matter in Patients With Primary Sclerosing Cholangitis and Orthotopic Liver Transplantation? A Systematic Review and Meta-analysis

Introduction

Pouchitis is the most common complication in patients with ileal pouch-anal anastomosis (IPAA), which can develop in up to 66% of patients. There is limited data on the effect of orthoptic liver transplantation (OLT) on the risk of developing pouchitis. We aimed to objectively assess whether OLT itself significantly modifies the risk of developing pouchitis in patients with overlap PSC and inflammatory bowel disease (IBD).

Method

We searched Medline, Scopus, and Embase databases from inception through September 2023 for studies that describe the outcomes of IPAA in patients with PSC and IBD who also have a history of OLT. Pooled proportions, Odds Ratio (OR), and 95% confidence intervals (CI) for data were calculated utilizing a random effects model. Using the Freeman-Turkey double arcsine transformation (FTT) method, the pooled weight-adjusted estimate of event rates for clinical outcomes in each group was also calculated. Heterogeneity between studies was assessed using the Cochrane Q statistic (I2).

Results

Seven studies with a total of 291 patients with a history of PSC, IBD, and OLT were identified. The pooled overall risk of pouchitis in PSC/IBD patients with a history of OLT was 65% (95% CI: 0.57-0.72), with no heterogeneity observed in the analysis (I2 = 0%). In a subgroup analysis of patients who had IPAA followed by OLT, 3 studies with 28 patients were included; the pooled risk of pouchitis after IPAA and OLT was 83% (95% CI: 0.71-0.94; I2 = 0%), which was significantly higher (P < .001) than the OLT followed by IPAA group (59%; 95 CI: 0.48-0.71; I2 = 0%). There was no difference in the risk of pouchitis between OLT and non-OLT groups (OR = 1.36; 95% CI: 0.37-5.0).

Conclusions

Our meta-analysis revelaed that pouchitis is common in patients who underwent OLT for PSC, especially in those who had IPAA before the OLT. OLT before IPAA may reduce the risk of pouchitis. Further larger studies are warranted to reproduce this and investigate the reason behind this difference.

Role of gut-liver axis and glucagon-like peptide-1 receptor agonists in the treatment of metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a hepatic manifestation of the metabolic syndrome. It is one of the most common liver diseases worldwide and shows increasing prevalence rates in most countries. MAFLD is a progressive disease with the most severe cases presenting as advanced fibrosis or cirrhosis with an increased risk of hepatocellular carcinoma. Gut microbiota play a significant role in the pathogenesis and progression of MAFLD by disrupting the gut-liver axis. The mechanisms involved in maintaining gut-liver axis homeostasis are complex. One critical aspect involves preserving an appropriate intestinal barrier permeability and levels of intestinal lumen metabolites to ensure gut-liver axis functionality. An increase in intestinal barrier permeability induces metabolic endotoxemia that leads to steatohepatitis. Moreover, alterations in the absorption of various metabolites can affect liver metabolism and induce liver steatosis and fibrosis. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are a class of drugs developed for the treatment of type 2 diabetes mellitus. They are also commonly used to combat obesity and have been proven to be effective in reversing hepatic steatosis. The mechanisms reported to be involved in this effect include an improved regulation of glycemia, reduced lipid synthesis, β-oxidation of free fatty acids, and induction of autophagy in hepatic cells. Recently, multiple peptide receptor agonists have been introduced and are expected to increase the effectiveness of the treatment. A modulation of gut microbiota has also been observed with the use of these drugs that may contribute to the amelioration of MAFLD. This review presents the current understanding of the role of the gut-liver axis in the development of MAFLD and use of members of the GLP-1 RA family as pleiotropic agents in the treatment of MAFLD.

Isolation of mucosa-associated microbiota dysbiosis in the ascending colon in hepatitis C virus post-sustained virologic response cirrhotic patients

Background

Achieving sustained virologic response (SVR) in patients infected with hepatitis C virus (HCV) reduces all-cause mortality. However, the mechanisms and risk factors for liver fibrosis and portal hypertension post-SVR remain incompletely understood. In the gut-liver axis, mucosa-associated microbiota (MAM) substantially influence immune and metabolic functions, displaying spatial heterogeneity at the anatomical intestinal site. We analyzed MAM composition and function to isolate the locoregional MAM involved in chronic liver disease progression in HCV post-SVR patients.

Methods

We collected MAM samples from three intestinal sites (terminal ileum, ascending colon, and sigmoid colon) via brushing during colonoscopy in 23 HCV post-SVR patients and 25 individuals without liver disease (controls). The 16S rRNA of bacterial DNA in specimens collected with a brush and in feces was sequenced. The molecular expression of intestinal tissues and hepatic tissues were evaluated by quantitative real-time PCR.

Results

In the post-SVR group, the microbial β-diversity of MAM, especially in the ascending colon, differed from the control group and was associated with liver fibrosis progression. In PICRUSt analysis, MAM in the ascending colon in the liver cirrhosis (LC) group showed compromised functions associated with the intestinal barrier and bile acid production, and FGF19 expression was markedly decreased in the terminal ileum biopsy tissue in the LC group. At the genus level, six short-chain fatty acid (SCFA)-producing bacterial genera, Blautia, Alistipes, Roseburia, Agathobaculum, Dorea, and Pseudoflavonifractor were reduced in the ascending colon of post-SVR LC patients.

Conclusion

In patients of HCV post-SVR, we identified the association between the degree of liver fibrosis and dysbiosis of mucosa-associated SCFA-producing bacterial genera that may be related to intestinal barrier and bile acid production in the ascending colon.

Low Short-Chain-Fatty-Acid-Producing Activity of the Gut Microbiota Is Associated with Hypercholesterolemia and Liver Fibrosis in Patients with Metabolic-Associated (Non-Alcoholic) Fatty Liver Disease

The aim of this study was to investigate the short-chain fatty acid (SCFA) activity of the gut microbiota of patients with metabolic-associated fatty liver disease (MAFLD). The level and spectrum of short-chain fatty acids (SCFAs) were determined via gas–liquid chromatography. Liver fibrosis was assessed using the FIB-4 index and elastography. Among 42 non-cirrhotic MAFLD patients, 24 had high fecal SCFA levels (group H) and 18 had low fecal SCFA levels (group L). Patients in group H had lower serum uric acid, total cholesterol, and LDL cholesterol levels but a higher BMI than those in group L. All patients in group L and only 37.9% of those in group H were found to have hypercholesterolemia. In patients with hypercholesterolemia, the level of SCFAs was lower than that in patients without hypercholesterolemia. Patients in group H had less liver fibrosis than patients in group L. A total of 50.0% of the patients in group H and 92.3% of those in group L had significant liver fibrosis (≥F2). Patients with significant liver fibrosis had lower levels of fecal SCFAs—particularly acetate and butyrate. The fecal SCFA levels were positively correlated with gamma-glutamyl transferase, total bilirubin levels, BMI, and platelet count and were negatively correlated with FIB-4, liver stiffness, serum total, and LDL cholesterol levels.