Bile acids and butyrate in the effects of probiotics/synbiotics on nonalcoholic fatty liver disease

Gut-Liver-Pancreas Axis Crosstalk in Health and Disease: From the Role of Microbial Metabolites to Innovative Microbiota Manipulating Strategies

The functions of the gut are closely related to those of many other organs in the human body. Indeed, the gut microbiota (GM) metabolize several nutrients and compounds that, once released in the bloodstream, can reach distant organs, thus influencing the metabolic and inflammatory tone of the host. The main microbiota-derived metabolites responsible for the modulation of endocrine responses are short-chain fatty acids (SCFAs), bile acids and glucagon-like peptide 1 (GLP-1). These molecules can (i) regulate the pancreatic hormones (insulin and glucagon), (ii) increase glycogen synthesis in the liver, and (iii) boost energy expenditure, especially in skeletal muscles and brown adipose tissue. In other words, they are critical in maintaining glucose and lipid homeostasis. In GM dysbiosis, the imbalance of microbiota-related products can affect the proper endocrine and metabolic functions, including those related to the gut-liver-pancreas axis (GLPA). In addition, the dysbiosis can contribute to the onset of some diseases such as non-alcoholic steatohepatitis (NASH)/non-alcoholic fatty liver disease (NAFLD), hepatocellular carcinoma (HCC), and type 2 diabetes (T2D). In this review, we explored the roles of the gut microbiota-derived metabolites and their involvement in onset and progression of these diseases. In addition, we detailed the main microbiota-modulating strategies that could improve the diseases' development by restoring the healthy balance of the GLPA.

Exploring the interplay of gut microbiota, inflammation, and LDL-cholesterol: a multiomics Mendelian randomization analysis of their causal relationship in acute pancreatitis and non-alcoholic fatty liver disease

BACKGROUND

Acute pancreatitis and non-alcoholic fatty liver disease are both serious diseases in the digestive system. The pathogenesis of both diseases is extremely complex closely and it related to gut microbiota, inflammation, and blood fat. There is a close relationship between gut microbiota and blood lipids.

METHODS

In this study, we used three types of exposure: 412 gut microbiota, 731 inflammatory cells, and 91 inflammatory proteins (pqtls), with LDL-C as an intermediary and acute pancreatitis and non-alcoholic fatty liver disease as outcomes. We mainly used MR-IVW, co-localization analysis, and reverse MR analysis methods for analysis.

RESULTS

7 gut microbiota, 21 inflammatory cells, and 3 inflammatory proteins can affect LDL-C levels. LDL-C is associated with acute pancreatitis and non-alcoholic fatty liver disease.

CONCLUSIONS

Three omics were used: 412 gut microbiota, 731 inflammatory cells, and 91 inflammatory proteins (pqtls). It explains the causal relationship between multiomics, LDL- cholesterol, acute pancreatitis, and non-alcoholic fatty liver disease.

Influence of genetically predicted autoimmune diseases on NAFLD

Introduction

Non-alcoholic fatty liver disease (NAFLD), the emerging cause of end-stage liver disease, is the most common liver disease. Determining the independent risk factors of NAFLD and patients who need more monitoring is important.

Methods

Two-Sample Mendelian randomization (MR) was performed in the analysis to investigate the causal association of different autoimmune diseases with NAFLD using summary level data. Genome-wide association study (GWAS) of 5 autoimmune diseases including celiac disease (CeD), Crohn's disease (CD), multiple sclerosis (MS), rheumatoid arthritis (RA), and type 1 diabetes (T1D) were selected for Instrument variables (IVs). NAFLD was included as outcome.

Result

After adjusting for confounding factors, genetic predisposition of CeD (OR= 0.973, [0.949,0.997], IVW p-value=0.026), MS (OR= 1.048, [1.012,1.085], IVW p-value= 0.008), RA (OR= 1.036, [1.006,1.066], IVW p-value=0.019), T1D (OR= 1.039, [1.002,1.079], IVW p-value= 0.041) is causally associated with NAFLD. No causal effect was found between CD and NAFLD.

Conclusion

CeD itself may be a protective factor for NAFLD, the results of previous observational studies have been influenced by confounding factors, and the morbidity of NAFLD may be higher in patients with MS, RA, and T1D than in common populations, and monitoring the prevalence of NAFLD in these populations is considerable.

Effects of Tylophora yunnanensis Schltr on regulating the gut microbiota and its metabolites in non-alcoholic steatohepatitis rats by inhibiting the activation of NOD-like receptor protein 3

ETHNOPHARMACOLOGICAL RELEVANCE

Tylophora yunnanensis Schltr (TYS) is widely distributed in Yunnan, Guizhou, and other places in China. It is commonly used by folks to treat hepatitis and other liver-related diseases; however, its mechanism of action is still unclear.

AIM OF THE STUDY

This study aimed to determine the effects of TYS on regulating gut microbiota and its metabolites in non-alcoholic steatohepatitis (NASH) rats by inhibiting the activation of NOD-like receptor protein3 (NLRP3).

MATERIAL AND METHODS

An HFD-induced rat model was established to investigate if the intragastric administration of TYS could mediate gut microbiota and their metabolites to ultimately improve the symptoms of NASH. The improving effects of TYS on NASH rats were assessed by measuring their body weight, lipid levels, histopathology, and inflammatory factor levels in the rat models. The regulatory effects of TYS on NLRP3 in the NASH rats were analyzed using real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA), which determined the levels of NLRP3-related factors. The changes in the composition of the gut microbiota of NASH rats were analyzed using 16S rRNA gene sequencing technology. Meanwhile, the Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used for the non-targeted analysis of metabolites in the cecum contents.

RESULTS

The results showed that TYS could improve NASH by decreasing the body weight and levels of lipid, AST, ALT, LPS, FFA, VLDL, IL-1β, IL-6, TNF-α, TGF-β, NLRP3, ASC, and Caspase-1 in the NASH rats. The analysis of gut microbiota showed that TYS could improve the diversity and abundance of gut microbiota and alter their composition by decreasing the Firmicutes/Bacteroidetes (F/B) ratio and relative abundances of Lachnospiraceae, Christensenellaceae, Blautia, etc. while increasing those of Muribaculaceae, Rumiaococcus, Ruminococcaceae, etc. The analysis of metabolites in the cecum contents suggested that the arachidonic acid metabolism, bile secretion, serotonergic synapse, Fc epsilon RI signaling pathway, etc. were regulated by TYS. The metabolites enriched in these pathways mainly included chenodeoxycholic acid, prostaglandin D2, TXB2, 9-OxoODE, and 13(S)-HOTrE.

CONCLUSIONS

These findings suggested that TYS could alleviate the NASH symptoms by decreasing the body weight, regulating the lipid levels, reducing the inflammatory response, and inhibiting the expression levels of NLRP3, ASC, and Caspase-1 in the NASH rats. The changes in the composition of gut microbiota and their metabolic disorder were closely related to the activation of NLRP3. TYS could significantly inhibit the activation of NLRP3 and regulate the composition of gut microbiota and the disorder of metabolites during NASH modeling.

Fagopyrum dibotrys extract alleviates hepatic steatosis and insulin resistance, and alters autophagy and gut microbiota diversity in mouse models of high-fat diet-induced non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a major global health concern with increasing prevalence, with a lack of currently available effective treatment options; thus, the investigation of novel therapeutic approaches is necessary. The study aimed to investigate the outcomes and mechanisms of action of Fagopyrum dibotrys extract (FDE) in a high-fat diet (HFD)-induced mouse model of obesity. The findings showed that FDE supplementation attenuated glucose tolerance, insulin resistance (IR), hepatic steatosis, and abnormal lipid metabolism. In addition, FDE also promoted autophagic activity and inhibited the phosphorylation of transcription factor EB in HFD-fed mice. Furthermore, gut microbiota characterization via 16S rRNA sequencing revealed that the supplementation of FDE increased Bacteroidetes and Verrucomicrobia populations while decreased Firmicutes, thus modifying the gut microbiome. FDE also increased the relative abundance of Akkermansia. Our findings suggest that FDE may protect against HFD-induced NAFLD by activating autophagy and alleviating dysbiosis in the gut microbiome. FDE may be beneficial as a nutraceutical treatment for NAFLD.

Helminth infection and helminth-derived products: A novel therapeutic option for non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is closely related to obesity, diabetes, and metabolic syndrome (MetS), and it has become the most common chronic liver disease. Helminths have co-evolved with humans, inducing multiple immunomodulatory mechanisms to modulate the host’s immune system. By using their immunomodulatory ability, helminths and their products exhibit protection against various autoimmune and inflammatory diseases, including obesity, diabetes, and MetS, which are closely associated with NAFLD. Here, we review the pathogenesis of NAFLD from abnormal glycolipid metabolism, inflammation, and gut dysbiosis. Correspondingly, helminths and their products can treat or relieve these NAFLD-related diseases, including obesity, diabetes, and MetS, by promoting glycolipid metabolism homeostasis, regulating inflammation, and restoring the balance of gut microbiota. Considering that a large number of clinical trials have been carried out on helminths and their products for the treatment of inflammatory diseases with promising results, the treatment of NAFLD and obesity-related diseases by helminths is also a novel direction and strategy.

Health Effects of Probiotics on Nonalcoholic Fatty Liver in the Life Cycle Based on Data Analysis

Objective

To observe the effect of intestinal probiotics in the treatment of nonalcoholic fatty liver disease (NAFLD) and the effect on liver function and inflammatory factors.

Methods

34 healthy rats were selected for the study and divided into 10 rats in the control group, 12 rats in the model group, and 12 rats in the treatment group according to the random number table method. The control group was given behavioral and lifestyle interventions, and the treatment group was given Bifidobacterium minus Black enteric capsules 5 g/(kg-d) by strong feeding method on the basis of the control group. The fatty liver index (FLI), liver ultrasound examination results, liver function, and inflammatory factor levels were compared among the three groups. After 8 weeks of treatment, there were statistically significant differences between the FLI values and liver ultrasound results of the three groups, and the serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), triacylglycerol (TG), and total cholesterol (TC) levels of the observation group were lower than those of the control group and the model group. The levels of serum high molecular weight lipocalin (HMW-APN) and interleukin 22 (IL-22) in the observation group were higher than those in the control group, and the levels of tumor necrosis factor-α (TNF-α) were lower than those in the control and model groups, and the differences were statistically significant (P < 0.05).

Conclusion

Intestinal probiotics can improve the clinical efficacy of patients with NAFLD, improve liver function, and alleviate the inflammatory response, in order to provide a theoretical basis for the clinical treatment of patients with NAFLD.

Gut Microbiota Metabolites in NAFLD Pathogenesis and Therapeutic Implications

Gut microbiota dysregulation plays a key role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) through its metabolites. Therefore, the restoration of the gut microbiota and supplementation with commensal bacterial metabolites can be of therapeutic benefit against the disease. In this review, we summarize the roles of various bacterial metabolites in the pathogenesis of NAFLD and their therapeutic implications. The gut microbiota dysregulation is a feature of NAFLD, and the signatures of gut microbiota are associated with the severity of the disease through altered bacterial metabolites. Disturbance of bile acid metabolism leads to underactivation of bile acid receptors FXR and TGR5, causal for decreased energy expenditure, increased lipogenesis, increased bile acid synthesis and increased macrophage activity. Decreased production of butyrate results in increased intestinal inflammation, increased gut permeability, endotoxemia and systemic inflammation. Dysregulation of amino acids and choline also contributes to lipid accumulation and to a chronic inflammatory status. In some NAFLD patients, overproduction of ethanol produced by bacteria is responsible for hepatic inflammation. Many approaches including probiotics, prebiotics, synbiotics, faecal microbiome transplantation and a fasting-mimicking diet have been applied to restore the gut microbiota for the improvement of NAFLD.

The gallbladder and vermiform appendix influence the assemblage of intestinal microorganisms

Surgical procedures for the symptomatic removal of the gallbladder and the vermiform appendix have been posited to adversely shift the assemblage of the intestinal microbiome increasing the risk of disease. The associated mechanisms have been linked with dysbiosis of the gut microbiota. Cholecystectomy causes changes of bile acid compositions and bile secretion patterns as bile acids interact with the intestinal microbiota in a bidirectional capacity. An appendectomy precludes the further recolonization of the proximal colon with a commensal biofilm that could maintain a stable intestinal microbiome. Epidemiological studies indicate that there is an increased risk of disease rather than causality following a cholecystectomy and appendectomy. This narrative review summarizes studies that report on the role that bile salts and the appendix, contribute to the assemblage of the intestinal microbiome in health and disease.