Targeting the gut-liver axis by modulating the gut-microbiome can be a promising therapeutic approach in nonalcoholic fatty liver disease (NAFLD). The aim of this study was to evaluate the effects of single species and a combination of Lactobacillus and Pediococcus in NAFLD mice model. Six-week male C57BL/6J mice were divided into 9 groups (n = 10/group; normal, Western diet, and 7 Western diet-strains [10 9 CFU/g, 8 weeks]). The strains used were L. bulgaricus, L. casei, L. helveticus, P. pentosaceus KID7, and three combinations (1: L. casei+L. helveticus, 2: L. casei+L. helveticus+P. pentosaceus KID7, and 3: L. casei+L. helveticus+L. bulgaricus). Liver/Body weight ratio, serum and stool analysis, liver pathology, and metagenomics by 16S rRNA-sequencing were examined. In the liver/body ratio, L. bulgaricus (5.1 ± 0.5), L. helveticus (5.2 ± 0.4), P. pentosaceus KID7 (5.5 ± 0.5), and combination1 and 2 (4.2 ± 0.6 and 4.8 ± 0.7) showed significant reductions compared with Western (6.2 ± 0.6)(p < 0.001). In terms of cholesterol and steatosis/inflammation/NAFLD activity, all groups except for L. casei were associated with an improvement (p < .05). The elevated level of tumor necrosis factor-α/interleukin-1β (pg/ml) in Western (65.8 ± 7.9/163.8 ± 12.2) was found to be significantly reduced in L. bulgaricus (24.2 ± 1.0/ 58.9 ± 15.3), L. casei (35.6 ± 2.1/62.9 ± 6.0), L. helveticus (43.4 ± 3.2/53.6 ± 7.5), and P. pentosaceus KID7 (22.9 ± 3.4/59.7 ± 12.2)(p < 0.01). Cytokines were improved in the combination groups. In metagenomics, each strains revealed a different composition and elevated Firmicutes/Bacteroidetes ratio in the western (47.1) was decreased in L. bulgaricus (14.5), L. helveticus (3.0), and P. pentosaceus KID7 (13.3). L. bulgaricus, L. casei, L. helveticus, and P. pentosaceus KID7 supplementation can improve NAFLDprogression by modulating gut-microbiome and inflammatory pathway.

Liver cirrhosis is one of the most prevalent chronic liver diseases worldwide. In addition to viral hepatitis, diseases such as steatohepatitis, autoimmune hepatitis, sclerosing cholangitis and Wilson’s disease can also lead to cirrhosis. Moreover, alcohol can cause cirrhosis on its own and exacerbate chronic liver disease of other causes. The treatment of cirrhosis can be divided into addressing the cause of cirrhosis and reversing liver fibrosis. To this date, there is still no clear consensus on the treatment of cirrhosis. Recently, there has been a lot of interest in potential treatments that modulate the gut microbiota and gut-liver axis for the treatment of cirrhosis. According to recent studies, modulation of the gut microbiome by probiotics ameliorates the progression of liver disease. The precise mechanism for relieving cirrhosis via gut microbial modulation has not been identified. This paper summarizes the role and effects of the gut microbiome in cirrhosis based on experimental and clinical studies on absorbable antibiotics, probiotics, prebiotics, and synbiotics. Moreover, it provides evidence of a relationship between the gut microbiome and liver fibrosis.

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Background Although microbioa‐based therapies have shown putative effects on the treatment of non‐alcoholic fatty liver disease (NAFLD), it is not clear how microbiota‐derived metabolites contribute to the prevention of NAFLD. We explored the metabolomic signature of Lactobacillus lactis and Pediococcus pentosaceus in NAFLD mice and its association in NAFLD patients. Methods We used Western diet‐induced NAFLD mice, and L. lactis and P. pentosaceus were administered to animals in the drinking water at a concentration of 10 9 CFU/g for 8 weeks. NAFLD severity was determined based on liver/body weight, pathology and biochemistry markers. Caecal samples were collected for the metagenomics by 16S rRNA sequencing. Metabolite profiles were obtained from caecum, liver and serum. Human stool samples (healthy control [ n = 22] and NAFLD patients [ n = 23]) were collected to investigate clinical reproducibility for microbiota‐derived metabolites signature and metabolomics biomarker. Results L. lactis and P. pentosaceus supplementation effectively normalized weight ratio, NAFLD activity score, biochemical markers, cytokines and gut‐tight junction. While faecal microbiota varied according to the different treatments, key metabolic features including short chain fatty acids (SCFAs), bile acids (BAs) and tryptophan metabolites were analogously restored by both probiotic supplementations. The protective effects of indole compounds were validated with in vitro and in vivo models, including anti‐inflammatory effects. The metabolomic signatures were replicated in NAFLD patients, accompanied by the comparable levels of Firmicutes / Bacteroidetes ratio, which was significantly higher (4.3) compared with control (0.6). Besides, the consequent biomarker panel with six stool metabolites (indole, BAs, and SCFAs) showed 0.922 (area under the curve) in the diagnosis of NAFLD. Conclusions NAFLD progression was robustly associated with metabolic dys‐regulations in the SCFAs, bile acid and indole compounds, and NAFLD can be accurately diagnosed using the metabolites. L. lactis and P. pentosaceus ameliorate NAFLD progression by modulating gut metagenomic and metabolic environment, particularly tryptophan pathway, of the gut‐liver axis.

Chronic liver disease encompasses diseases that have various causes, such as alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD). Gut microbiota dysregulation plays a key role in the pathogenesis of ALD and NAFLD through the gut–liver axis. The gut microbiota consists of various microorganisms that play a role in maintaining the homeostasis of the host and release a wide number of metabolites, including short-chain fatty acids (SCFAs), peptides, and hormones, continually shaping the host’s immunity and metabolism. The integrity of the intestinal mucosal and vascular barriers is crucial to protect liver cells from exposure to harmful metabolites and pathogen-associated molecular pattern molecules. Dysbiosis and increased intestinal permeability may allow the liver to be exposed to abundant harmful metabolites that promote liver inflammation and fibrosis. In this review, we introduce the metabolites and components derived from the gut microbiota and discuss their pathologic effect in the liver alongside recent advances in molecular-based therapeutics and novel mechanistic findings associated with the gut–liver axis in ALD and NAFLD.