Turnover of bile acids in liver, serum and caecal content by high-fat diet feeding affects hepatic steatosis in rats

Probiotic Mixture Ameliorates a Diet-Induced MASLD/MASH Murine Model through the Regulation of Hepatic Lipid Metabolism and the Gut Microbiome

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent metabolic disease that has no effective treatment. Our proprietary probiotic mixture, Prohep, has been proven in a previous study to be helpful in reducing hepatocellular carcinoma (HCC) in vivo. However, its prospective benefits on the treatment of other liver diseases such as MASLD, which is one of the major risk factors in the development of HCC, are unclear. To investigate the potential of Prohep in modulating the development and progression of MASLD, we first explored the effect of Prohep supplementation via voluntary intake in a high-fat diet (HFD)-induced MASLD/metabolic dysfunction-associated steatohepatitis (MASH) murine model. Our results indicated that Prohep alleviated HFD-induced liver steatosis and reduced excessive hepatic lipid accumulation and improved the plasma lipid profile when compared with HFD-fed control mice through suppressing hepatic de novo lipogenesis and cholesterol biosynthesis gene expressions. In addition, Prohep was able to modulate the gut microbiome, modify the bile acid (BA) profile, and elevate fecal short-chain fatty acid (SCFA) levels. Next, in a prolonged HFD-feeding MASLD/MASH model, we observed the effectiveness of Prohep in preventing the transition from MASLD to MASH via amelioration in hepatic steatosis, inflammation, and fibrosis. Taken together, Prohep could ameliorate HFD-induced MASLD and control the MASLD-to-MASH progression in mice. Our findings provide distinctive insights into the development of novel microbial therapy for the management of MASLD and MASH.

Understanding the role of ursodeoxycholic acid and gut microbiome in non-alcoholic fatty liver disease: current evidence and perspectives

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, resulting in a huge medical burden worldwide. Accumulating evidence suggests that the gut microbiome and bile acids play pivotal roles during the development of NAFLD. Patients with NAFLD exhibit unique signatures of the intestinal microbiome marked by the priority of Gram-negative bacteria, decreased ratio of Firmicutes/Bacteroidetes (F/B), and increased Prevotella and Lachnospiraceae. The intestinal microbiota is involved in the metabolism of bile acids. Ursodeoxycholic acid (UDCA) is a key determinant in maintaining the dynamic communication between the host and gut microbiota. It generally shows surprising therapeutic potential in NAFLD with several mechanisms, such as improving cellular autophagy, apoptosis, and mitochondrial functions. This action is based on its direct or indirect effect, targeting the farnesoid X receptor (FXR) and various other nuclear receptors. This review aims to discuss the current studies on the involvement of the microbiome-UDCA interface in NAFLD therapy and provide prospective insights into future preventative and therapeutic approaches for NAFLD.

Astragalus polysaccharide attenuates nonalcoholic fatty liver disease through THDCA in high-fat diet-fed mice

ETHNOPHARMACOLOGICAL RELEVANCE

Astragalus polysaccharide (APS) extracted from Astragalus membranaceus (Fisch.) Bunge was proven to be effective in preventing high-fat diet (HFD) induced nonalcoholic fatty liver disease (NAFLD). However, the exact mechanisms were not completely elucidated.

AIM OF THE STUDY

The aim was to reveal the mechanisms of APS on preventing NAFLD from the aspects of regulating bile acids (BAs) homeostasis.

MATERIALS AND METHODS

Serum and liver BAs in HFD fed mice with or without APS intervention were quantified with an ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) system. The effect of APS on hepatic proteins involved in BAs synthesis were analyzed with Western blot. Finally, the effect of identified taurohyodeoxycholic acid (THDCA) that was significantly increased by APS on hepatic triglyceride (TG) accumulation was explored in vivo and in vitro.

RESULTS

APS regulated serum and liver BA profiles in HFD fed mice, especially increased serum THDCA. The levels of hepatic cholesterol 7a-hydroxylase (CYP7A1) and sterol 12a-hydroxylase (CYP8B1) which catalyzed the classical BAs synthesis pathway were significantly decreased by APS, while oxysterol 7a-hydroxylase (CYP7B1) which catalyzed the alternative BAs synthesis pathway was significantly increased by APS. THDCA reduced HFD-induced hepatic lipid accumulation and improved glucose homeostasis in mice, and decreased TG level in palmitic acid/oleic acid treated alpha mouse liver 12 (AML-12) cells. THDCA significantly downregulated the protein level of cluster of differentiation 36 (CD36) involved in fatty acid transport into the liver. Importantly, THDCA showed similar effect with APS in upregulating hepatic CYP7B1 and downregulating CYP7A1.

CONCLUSION

This study revealed the protective effect of APS on NAFLD was associated with the regulation on BA profiles, and proved the potential anti-NAFLD effect of THDCA, highlighting the involvement of BA metabolism in efficacy of herb-derived polysaccharides on metabolism.

Protective effects of scutellaria-coptis herb couple against non-alcoholic steatohepatitis via activating NRF2 and FXR pathways in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellaria-coptis herb couple (SC) is a classic herbal pair used in many Traditional Chinese Medicine (TCM) formulations in the treatment of endocrine and metabolic deseases. Diabetes mellitus and non-alcoholic steatohepatitis (NASH) are both endocrine and metabolic diseases. Previous studies have shown that SC has anti-diabetic effects. However, the effect and mechanism of SC against NASH remains unclear.

AIM OF THE STUDY

This study aimed to demonstrate the effect and mechanism of SC against NASH through the nuclear factor-erythroid 2-related factor 2 (Nrf2) and farnesoid X receptor (FXR) dual signaling pathways in vivo and in vitro.

MATERIALS AND METHODS

The high fat diet-fed rat model, and HepG2 and RAW264.7 cell models were used. Serum biochemical indexes and liver histopathological changes were examined. Metabolomics, transcriptomics, and flow cytometry were performed. RT-qPCR and western blot analysis were performed to provide expression of NRF2 and FXR pathway signal molecules during SC's anti-NASH treatment in vivo and in vitro.

RESULTS

SC had anti-NASH effects in vivo with significantly improvement of serum NASH biochemical index and hepatopathological structure; meanwhile, SC significantly elevated the expression levels of FXR protein in liver and intestinal tissues, and cholesterol 7a-hydroxylase (CYP7A1) protein in liver. The mRNA expression levels of Takeda G protein receptor 5 (TGR5), CYP7A1, fibroblast growth factor receptor-4 (FGFR4), FXR, small heterodimer partner (SHP), fibroblast growth factor 15/19 (FGF15/19) and glucagon-like peptide-1 (GLP-1) were significantly elevated by SC. SC reduced the levels of NorCA, isoLCA and α-MCA in the feces of NAFLD rats. In vitro, SC-containing serum (SC-CS) was found to significantly reduce intracellular lipid deposition, inhibit ROS production, reduce intracellular Malondialdehyde (MDA) and IL-1β levels, and enhance the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Six differential genes closely related to oxidative stress and Nrf2 were identified by transcriptomic analysis. SC-CS up-regulated the expression of NRF2, and reduced the expression of TXNIP and Caspase-1 genes in RAW264.7 cells. In addition, SC-CS reduced the expression of Keap1 and NF-κB, and up-regulated the expression of Nrf2, heme oxygenase-1 (HO-1), quinone oxidoreductase 1 (NQO1), and SOD; SC-CS elevated the protein level of NRF2, and reduced the protein level of TXNIP in HepG2 cells.

CONCLUSIONS

the mechanisms of SC action against NASH was closely related to the simultaneous activations of both NRF2 and FXR signaling pathways. These findings provide a new insight into the anti-NASH application of SC in clinical settings and demonstrate the potential of SC in the treatment of NASH.

Dietary polyphenols maintain homeostasis via regulating bile acid metabolism: a review of possible mechanisms

The synthesis and metabolism of bile acids (BAs) have been implicated in various metabolic diseases, including obesity and diabetes. Dietary polyphenols, as natural antioxidants, play a vital role in synthesizing and metabolizing bile acids. This paper reviews the mechanism of dietary polyphenols involved in bile acid (BA) synthesis and metabolism. The impact of different gut microorganisms on BA profiles is discussed in detail. The regulation of BA metabolism by dietary polyphenols can be divided into two modes: (1) dietary polyphenols directly activate/inhibit farnesol X receptor (FXR) and Takeda G protein-coupled receptor (TGR5); (2) dietary polyphenols regulate BA synthesis and metabolism through changes in intestinal microorganisms. Research on direct activation/inhibition of FXR and TGR5 by polyphenols should be ramped up. In addition, the effect of dietary polyphenols on intestinal microorganisms has been paid more and more attention and has become a target that cannot be ignored.

Hyodeoxycholic acid ameliorates nonalcoholic fatty liver disease by inhibiting RAN-mediated PPARα nucleus-cytoplasm shuttling

Nonalcoholic fatty liver disease (NAFLD) is usually characterized with disrupted bile acid (BA) homeostasis. However, the exact role of certain BA in NAFLD is poorly understood. Here we show levels of serum hyodeoxycholic acid (HDCA) decrease in both NAFLD patients and mice, as well as in liver and intestinal contents of NAFLD mice compared to their healthy counterparts. Serum HDCA is also inversely correlated with NAFLD severity. Dietary HDCA supplementation ameliorates diet-induced NAFLD in male wild type mice by activating fatty acid oxidation in hepatic peroxisome proliferator-activated receptor α (PPARα)-dependent way because the anti-NAFLD effect of HDCA is abolished in hepatocyte-specific Pparα knockout mice. Mechanistically, HDCA facilitates nuclear localization of PPARα by directly interacting with RAN protein. This interaction disrupts the formation of RAN/CRM1/PPARα nucleus-cytoplasm shuttling heterotrimer. Our results demonstrate the therapeutic potential of HDCA for NAFLD and provide new insights of BAs on regulating fatty acid metabolism.

Hepatic steatosis is associated with dysregulated cholesterol metabolism and altered protein acetylation dynamics in chickens

BACKGROUND

Hepatic steatosis is a prevalent manifestation of fatty liver, that has detrimental effect on the health and productivity of laying hens, resulting in economic losses to the poultry industry. Here, we aimed to systematically investigate the genetic regulatory mechanisms of hepatic steatosis in laying hens.

METHODS

Ninety individuals with the most prominent characteristics were selected from 686 laying hens according to the accumulation of lipid droplets in the liver, and were graded into three groups, including the control, mild hepatic steatosis and severe hepatic steatosis groups. A combination of transcriptome, proteome, acetylome and lipidome analyses, along with bioinformatics analysis were used to screen the key biological processes, modifications and lipids associated with hepatic steatosis.

RESULTS

The rationality of the hepatic steatosis grouping was verified through liver biochemical assays and RNA-seq. Hepatic steatosis was characterized by increased lipid deposition and multiple metabolic abnormalities. Integration of proteome and acetylome revealed that differentially expressed proteins (DEPs) interacted with differentially acetylated proteins (DAPs) and were involved in maintaining the metabolic balance in the liver. Acetylation alterations mainly occurred in the progression from mild to severe hepatic steatosis, i.e., the enzymes in the fatty acid oxidation and bile acid synthesis pathways were significantly less acetylated in severe hepatic steatosis group than that in mild group (P < 0.05). Lipidomics detected a variety of sphingolipids (SPs) and glycerophospholipids (GPs) were negatively correlated with hepatic steatosis (r ≤ -0.5, P < 0.05). Furthermore, the severity of hepatic steatosis was associated with a decrease in cholesterol and bile acid synthesis and an increase in exogenous cholesterol transport.

CONCLUSIONS

In addition to acquiring a global and thorough picture of hepatic steatosis in laying hens, we were able to reveal the role of acetylation in hepatic steatosis and depict the changes in hepatic cholesterol metabolism. The findings provides a wealth of information to facilitate a deeper understanding of the pathophysiology of fatty liver and contributes to the development of therapeutic strategies.

The Potential of Bile Acids as Biomarkers for Metabolic Disorders

Bile acids (BAs) are well known to facilitate the absorption of dietary fat and fat-soluble molecules. These unique steroids also function by binding to the ubiquitous cell membranes and nuclear receptors. As chemical signals in gut-liver axis, the presence of metabolic disorders such as nonalcoholic fatty liver disease (NAFLD), type 2 diabetes mellitus (T2DM), and even tumors have been reported to be closely related to abnormal levels of BAs in the blood and fecal metabolites of patients. Thus, the gut microbiota interacting with BAs and altering BA metabolism are critical in the pathogenesis of numerous chronic diseases. This review intends to summarize the mechanistic links between metabolic disorders and BAs in gut-liver axis, and such stage-specific BA perturbation patterns may provide clues for developing new auxiliary diagnostic means.

Supplemental Clostridium butyricum modulates lipid metabolism by reshaping the gut microbiota composition and bile acid profile in IUGR suckling piglets

BACKGROUND

Intrauterine growth restriction (IUGR) can cause lipid disorders in infants and have long-term adverse effects on their growth and development. Clostridium butyricum (C. butyricum), a kind of emerging probiotics, has been reported to effectively attenuate lipid metabolism dysfunctions. Therefore, the objective of this study was to investigate the effects of C. butyricum supplementation on hepatic lipid disorders in IUGR suckling piglets.

METHODS

Sixteen IUGR and eight normal birth weight (NBW) neonatal male piglets were used in this study. From d 3 to d 24, in addition to drinking milk, the eight NBW piglets (NBW-CON group, n = 8) and eight IUGR piglets (IUGR-CON group, n = 8) were given 10 mL sterile saline once a day, while the remaining IUGR piglets (IUGR-CB group, n = 8) were orally administered C. butyricum at a dose of 2 × 10⁸ colony-forming units (CFU)/kg body weight (suspended in 10 mL sterile saline) at the same frequency.

RESULTS

The IUGR-CON piglets exhibited restricted growth, impaired hepatic morphology, disordered lipid metabolism, increased abundance of opportunistic pathogens and altered ileum and liver bile acid (BA) profiles. However, C. butyricum supplementation reshaped the gut microbiota of the IUGR-CB piglets, characterized by a decreased abundance of opportunistic pathogens in the ileum, including Streptococcus and Enterococcus. The decrease in these bile salt hydrolase (BSH)-producing microbes increased the content of conjugated BAs, which could be transported to the liver and function as signaling molecules to activate liver X receptor α (LXRα) and farnesoid X receptor (FXR). This activation effectively accelerated the synthesis and oxidation of fatty acids and down-regulated the total cholesterol level by decreasing the synthesis and promoting the efflux of cholesterol. As a result, the growth performance and morphological structure of the liver improved in the IUGR piglets.

CONCLUSION

These results indicate that C. butyricum supplementation in IUGR suckling piglets could decrease the abundance of BSH-producing microbes (Streptococcus and Enterococcus). This decrease altered the ileum and liver BA profiles and consequently activated the expression of hepatic LXRα and FXR. The activation of these two signaling molecules could effectively normalize the lipid metabolism and improve the growth performance of IUGR suckling piglets.

Synergistic effect of polysaccharides and flavonoids on lipid and gut microbiota in hyperlipidemic rats

Hyperlipidemia is a global health risk factor, and its development is closely related to the absorption and metabolism of lipids in the intestine. In this study, the Auricularia auricula polysaccharide, the Tremella polysaccharide, and hawthorn flavonoids were mixed by equal weight (HDC), and then its effect on the intervention in the intestine and blood lipids of hyperlipidemic rats on a high-fat diet (HFD) was investigated. The results revealed that HDC significantly inhibited the development of hyperlipidemia and reduced lipid levels and fat accumulation. In addition, HDC improved the edema deformation of intestinal epithelial cells, impaired the intestinal barrier induced by HFD, and improved the antioxidant capacity of the intestine. HDC showed a significant synergistic effect. Analysis of the gut microbiota by 16s rRNA gene sequencing showed that HDC reduced the ratio of Bacteroidetes/Firmicutes and the relative abundance of actinomycetes. At the genus level, the relative abundance of Lactobacillus, Rumincococcaceae-UCG-14, and Muribaculaceae was increased and the relative abundance of Allobaculum, Corynebacterium-1, Blautia, and Turicibucter was decreased. Intestinal lipidomics showed that HDC reduced the levels of DGDG, LPE, PG, phSM, PIP2, SoG1, and SM in the intestine of HFD rats, although there were no significant differences in LPE, PG, and phSM. 42 HDC-acting lipid biomarkers were screened. In conclusion, these findings support the potential of HDC intervention to prevent hyperlipidemia by regulating gut microbiota and lipid absorption and metabolism in the intestine.

High-grain diet feeding alters ileal microbiota and disrupts bile acid metabolism in lactating dairy cows

Bile acids (BAs) play an important role in the regulation of lipid metabolic homeostasis, but little is known about their metabolism in dairy cows fed a high-grain (HG) diet. In the present study, we examined the bacterial community, BA profile, and the FXR/FGF19 signaling pathway in the ileum and liver to investigate the gut microbe-BA metabolism interactions response to HG diet and the changes in the subsequent enterohepatic circulation of dairy cows. The results showed that the ileal bacterial community was altered, with an increase of Paraclostridium, Anaerobutyricum, Shuttleworthia, and Stomatobaculum in the relative abundance in the HG group. Moreover, real-time polymerase chain reaction (PCR) showed that the abundance of total bacteria and bacterial bile-salt hydrolase (BSH) genes was increased in the ileal digesta in the HG group. Meanwhile, HG feeding also decreased the total BA content in the digesta of jejunum and ileum and in feces. HG feeding altered the BA profile in the ileal digesta by increasing unconjugated BAs and decreasing conjugated BAs. In addition, the intestinal FXR/FGF19 signaling pathway was activated. The expression of CYP7A1 (cholesterol 7α-hydroxylase) was depressed, which inhibited BAs synthesis in the liver of cows fed HG. Overall, HG feeding altered the ileal bacterial community and BA profile, and activated FXR/FGF19 signaling pathway, resulting in a decrease of BA level in the ileal digesta via the inhibition of hepatic BA synthesis. The findings provided novel insights into understanding the relationship between gut microbiota and the homeostasis of BAs in dairy cows fed a HG diet.

Interventions for non-alcoholic liver disease: a gut microbial metabolites perspective

Over the past two decades, non-alcoholic fatty liver disease (NAFLD) has become a leading burden of hepatocellular carcinoma and liver transplantation. Although the exact pathogenesis of NAFLD has not been fully elucidated, recent hypotheses placed more emphasis on the crucial role of the gut microbiome and its derivatives. Reportedly, microbial metabolites such as short-chain fatty acids, amino acid metabolites (indole and its derivatives), bile acids (BAs), trimethylamine N-oxide (TMAO), and endogenous ethanol exhibit sophisticated bioactive properties. These molecules regulate host lipid, glucose, and BAs metabolic homeostasis via modulating nutrient absorption, energy expenditure, inflammation, and the neuroendocrine axis. Consequently, a broad range of research has studied the therapeutic effects of microbiota-derived metabolites. In this review, we explore the interaction of microbial products and NAFLD. We also discuss the regulatory role of existing NAFLD therapies on metabolite levels and investigate the potential of targeting those metabolites to relieve NAFLD.

The fungicide prothioconazole and its metabolite prothioconazole-desthio disturbed the liver-gut axis in mice

The triazole fungicide prothioconazole (PTC) can cause adverse effects in animals, and its main metabolite prothioconazole-desthio (PTC-d) is even much more harmful. However, the toxic effects of PTC and PTC-d on the liver-gut axis of mice are still unknown. In the present experiment, we found that oral exposure to PTC and PTC-d increased total bile acids (TBAs) levels in the serum, liver, and feces. Correspondingly, the transcription of genes involved in bile acids (BAs) disposition was significantly influenced by PTC or PTC-d exposure. Furthermore, the BAs composition of serum BAs was analyzed by LC-MS, and the results indicated that PTC and PTC-d exposure changed the BAs composition, lowered the ratio of conjugated/unconjugated BAs, elevated the ratio of CA/b-MCA, and enhanced the hydrophobicity of BAs pool. 16s RNA gene sequencing of the DNA from colonic contents uncovered that PTC and PTC-d exposure altered the relative abundance and constitution of intestinal microbiota, increasing the relative level of Lactobacillus with bile salt hydrolase (BSH) activity. Furthermore, PTC and PTC-d exposure impaired the gut barrier function, causing an increase in mucus secretion. In particular, the effects of PTC-d on some endpoints in the BAs metabolism and gut barrier function had been proven to be more significant than the parent compound PTC. All these findings draw attention to the health risk of PTC and PTC-d exposure in regulating BAs metabolism, which might lead to some metabolic disorders and occur of related diseases in animals.

Kaempferol attenuates nonalcoholic steatohepatitis by regulating serum and liver bile acid metabolism

Objective: Changes in bile acids (BAs) are increasingly recognized as potential targets for non-alcoholic steatohepatitis (NASH). Kaempferol has been proved to be anti-inflammatory and reduce the disorder of lipid metabolism. In order to analyze the BA profile in NASH mice and determine the predictive biomarkers of kaempferol treatment, serum-targeted metabolomics and liver tissue RNA sequencing (RNA-seq) were carried out.

Design: Six normal control mice (NC group), eight HFD-fed mice (HFD group), and eight kaempferol-treated HFD-fed mice (HFD + KP group) were included in the present study. Ultra-performance liquid chromatography coupled to a tandem mass spectrometry system (UPLC-MS/MS) was used to quantify serum and liver BAs, and RNA-seq was used to quantify liver differentially expressed genes related to BA metabolism.

Results: The serum levels of CA, βMCA, UDCA, and 12-DHCA, as well as ωMCA in both the serum and liver, were significantly decreased in the HFD group compared with those in the NC group, and kaempferol can increase the serum levels of βMCA, UDCA, and ωMCA and the liver level of 12-DHCA. The serum levels of TDCA, THDCA, TUDCA, TDCA/CA, and TDCA/DCA were significantly increased in the HFD group compared with those of the NC group, and kaempferol can decrease them. Furthermore, NASH mice had a higher liver level of total CA%, total CDCA%, primary BAs/secondary BAs, 12α-OH BAs/non-12α-OH Bas, and conjugated BAs/unconjugated BAs, and all decreased after kaempferol treatment. According to the RNA-seq results, we found that compared with the NC group, the mRNA expression of cholesterol-7α-hydroxylase (CYP7A1) in the HFD group was significantly increased, and the mRNA expression of sterol 12α‐hydroxylase (CYP8B1) and multidrug resistance-related protein 3 (MRP3) was significantly decreased, while kaempferol significantly promoted the mRNA expression of mitochondrial sterol 27-hydroxylase (CYP27A1) and Na⁺ -taurocholate cotransporting polypeptide (NTCP).

Conclusion: βMCA, CA, UDCA, 12-DHCA, ωMCA, CDCA, TωMCA, TDCA, THDCA, TCDCA, and TUDCA in the serum, as well as 6,7-diketoLCA, 12-DHCA, and ωMCA in the liver, may be potential biomarkers for kaempferol to improve NASH. HFD-induced NASH may be associated with the increase of CYP7A1 and the decrease of CYP8B1, leading to increased BA synthesis, and the decrease of MRP3 leading to decreased BA synthesis, and kaempferol may alleviate NASH by increasing CYP27A1 and NTCP to enhance BA transport.

Multi-Omics Reveals Inhibitory Effect of Baicalein on Non-Alcoholic Fatty Liver Disease in Mice

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, whose etiology is poorly understood. Accumulating evidence indicates that gut microbiota plays an important role in the occurrence and progression of various human diseases, including NAFLD. In this study, NAFLD mouse models were established by feeding a high-fat diet (HFD). Baicalein, a natural flavonoid with multiple biological activities, was administered by gavage, and its protective effect on NAFLD was analyzed by histopathological and blood factor analysis. Gut microbiota analysis demonstrated that baicalein could remodel the overall structure of the gut microbiota from NAFLD model mice, especially Anaerotruncus, Lachnoclostridium, and Mucispirillum. Transcriptomic analysis showed baicalein restored the expressions of numerous genes that were upregulated in hepatocytes of NAFLD mice, such as Apoa4, Pla2g12a, Elovl7, Slc27a4, Hilpda, Fabp4, Vldlr, Gpld1, and Apom. Metabolomics analysis proved that baicalein mainly regulated the processes associated with lipid metabolism, such as alpha-Linolenic acid, 2-Oxocarboxylic acid, Pantothenate and CoA biosynthesis, and bile secretion. Multi-omics analysis revealed that numerous genes regulated by baicalein were significantly correlated with pathways related to lipid metabolism and biosynthesis and secrection of bile acid, and baicalein might affect lipid metabolism in liver via regulating the ecological structure of gut microbiota in NAFLD mice. Our results elucidated the correlated network among diet, gut microbiota, metabolomic, and transcriptional profiling in the liver. This knowledge may help explore novel therapeutic approaches against NAFLD.

Hyperoside attenuates non-alcoholic fatty liver disease in rats via cholesterol metabolism and bile acid metabolism

Introduction

Non-alcoholic fatty liver disease (NAFLD) results from increased hepatic total cholesterol (TC) and total triglyceride (TG) accumulation. In our previous study, we found that rats treated with hyperoside became resistant to hepatic lipid accumulation.

Objectives

The present study aims to investigate the possible mechanisms responsible for the inhibitory effects of hyperoside on the lipid accumulation in the liver tissues of the NAFLD rats.

Methods

Label-free proteomics and metabolomics targeting at bile acid (BA) metabolism were applied to disclose the mechanisms for hyperoside reducing hepatic lipid accumulation among the NAFLD rats.

Results

In response to hyperoside treatment, several proteins related to the fatty acid degradation pathway, cholesterol metabolism pathway, and bile secretion pathway were altered, including ECI1, Acnat2, ApoE, and BSEP, etc. The expression of nuclear receptors (NRs), including farnesoid X receptor (FXR) and liver X receptor α (LXRα), were increased in hyperoside-treated rats' liver tissue, accompanied by decreased protein expression of catalyzing enzymes in the hepatic de novo lipogenesis and increased protein level of enzymes in the classical and alternative BA synthetic pathway. Liver conjugated BAs were less toxic and more hydrophilic than unconjugated BAs. The BA-targeted metabolomics suggest that hyperoside could decrease the levels of liver unconjugated BAs and increase the levels of liver conjugated BAs.

Conclusions

Taken together, the results suggest that hyperoside could improve the condition of NAFLD by regulating the cholesterol metabolism as well as BAs metabolism and excretion. These findings contribute to understanding the mechanisms by which hyperoside lowers the cholesterol and triglyceride in NAFLD rats.

Emerging trends and hotspots in the links between the gut microbiota and MAFLD from 2002 to 2021: A bibliometric analysis

BACKGROUND

The prevalence of metabolic associated fatty liver disease (MAFLD) presented a booming growth over recent years in the whole world. MAFLD was associated with a higher risk of end-stage liver disease, hepatocellular carcinoma and liver transplantation. Accumulating evidence indicated that gut microbiota and MAFLD were interrelated and interacted with each other. However, to the knowledge of the authors, no bibliometric quantitative analysis has been carried out to evaluate the links between the gut microbiota and MAFLD. This study aimed to use bibliometric analysis to evaluate current publication trends and hotspots in the links between the gut microbiota and MAFLD, in order to advance research in this field.

METHODS

The articles regarding the links between gut microbiota and MAFLD from 2002 to 2021 were identified from the Science Citation Index-Expanded of Web of Science Core Collection. CiteSpace software, Vosviewer, the R package "bibliometrix" and the Online Analysis Platform of Literature Metrology were used to analyze current publication trends and hotspots in this field.

RESULTS

A total of 707 articles were retrieved regarding the links between gut microbiota and MAFLD from 2002 to 2021. The USA occupied the leading role until 2015 and the dominance of China started in 2016. The USA was the most frequently involved country in international cooperation. Shanghai Jiao Tong University was the most productive institution. Ina Bergheim was the most productive author, publishing 14 articles. The co-citation keywords cluster label displayed ten main clusters: probiotics, bile acid, immune function, adolescents, nutritional genomics, high fat diet, systems biology, lipopolysaccharides, phosphatidylcholine, and oxidative stress. Keyword bursts analysis indicated that diet induced obesity, metabolic syndrome, ppar alpha, and lactobacillus were the research hotspots with high strength.

CONCLUSION

The number of publications covering the links of gut microbiota and MAFLD increased dramatically in the past decade and especially became exponential growth in the last 3 years. Probiotics and bile acid will be the research direction of great importance in the etiology and novel treatment for MAFLD. This study provided systematic information and instructive assistance for future research work, that helped to discover the mechanisms and new treatments of MAFLD.

Beneficial effects of inorganic nitrate in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is considered the hepatic representation of the metabolic disorders. Inorganic nitrate/nitrite can be converted to nitric oxide, regulate glucose metabolism, lower lipid levels, and reduce inflammation, thus raising the hypothesis that inorganic nitrate/nitrite could be beneficial for improving NAFLD. This study assessed the therapeutic effects of chronic dietary nitrate on NAFLD in a mouse model. 60 ApoE-/- mice were fed a high-fat diet (HFD) for 12 weeks to allow for the development of atherosclerosis with associated NAFLD. The mice were then randomly assigned to different groups (20/group) for a further 12 weeks: (i) HFD + NaCl (1 mmol/kg/day), (ii) HFD + NaNO3 (1 mmol/kg/day), and (iii) HFD + NaNO3 (10 mmol/kg/day). A fourth group of ApoE-/- mice consumed a normal chow diet for the duration of the study. At the end of the treatment, caecum contents, serum, and liver were collected. Consumption of the HFD resulted in significantly greater lipid accumulation in the liver compared to mice on the normal chow diet. Mice whose HFD was supplemented with dietary nitrate for the second half of the study, showed an attenuation in hepatic lipid accumulation. This was also associated with an increase in hepatic AMPK activity compared to mice on the HFD. In addition, a significant difference in bile acid profile was detected between mice on the HFD and those receiving the high dose nitrate supplemented HFD. In conclusion, dietary nitrate attenuates the progression of liver steatosis in ApoE-/- mice fed a HFD.

Untargeted serum metabolites profiling in high-fat diet mice supplemented with enhanced palm tocotrienol-rich fraction using UHPLC-MS

Excessive high fat dietary intake promotes risk of developing non-alcoholic fatty liver disease (NAFLD) and predisposed with oxidative stress. Palm based tocotrienol-rich fraction (TRF) has been reported able to ameliorate oxidative stress but exhibited poor bioavailability. Thus, we investigated whether an enhanced formulation of TRF in combination with palm kernel oil (medium-chain triglycerides) (ETRF) could ameliorate the effect of high-fat diet (HFD) on leptin-deficient male mice. All the animals were divided into HFD only (HFD group), HFD supplemented with ETRF (ETRF group) and HFD supplemented with TRF (TRF group) and HFD supplemented with PKO (PKO group). After 6 weeks, sera were collected for untargeted metabolite profiling using UHPLC-Orbitrap MS. Univariate analysis unveiled alternation in metabolites for bile acids, amino acids, fatty acids, sphingolipids, and alkaloids. Bile acids, lysine, arachidonic acid, and sphingolipids were downregulated while xanthine and hypoxanthine were upregulated in TRF and ETRF group. The regulation of these metabolites suggests that ETRF may promote better fatty acid oxidation, reduce oxidative stress and pro-inflammatory metabolites and acts as anti-inflammatory in fatty liver compared to TRF. Metabolites regulated by ETRF also provide insight of its role in fatty liver. However, further investigation is warranted to identify the mechanisms involved.

Activation of the gut microbiota-kynurenine-liver axis contributes to the development of nonalcoholic hepatic steatosis in nondiabetic adults

The contribution of gut-liver signaling to the development of non-alcoholic hepatic steatosis (NHS) in non-diabetic adults remains unclear. We therefore performed comprehensive 16S ribosomal RNA sequencing and fecal metabolomics analyses in 32 controls and 59 non-diabetic adults with NHS and performed fecal microbiota transplantation into germ-free mice using controls and NHS patients as donors. Compared to controls, the abundance of the genera Collinsella and Acinetobacter were higher, while that of Lachnospira was lower, in NHS subjects. Fecal metabolomics analysis showed decreased L-tryptophan levels and increased abundance of the tryptophan metabolite kynurenine in individuals with NHS. Correlation analysis showed that kynurenine levels positively associated with the abundance of Collinsella and Acinetobacter. ROC analysis demonstrated that the combination of tryptophan and kynurenine could discriminate NHS patients from controls with good statistical power [P < 0.05; AUC = 0.833 (95% CI, 0.747 to 0.918)]. Supporting a key role of dysbiotic gut microbiota in NHS development, incipient hepatic steatosis and increased kynurenine levels were observed in GF mice colonized with samples from NHS patients. These results indicate that enhanced kynurenine production resulting from altered gut microbiota composition contributes to NHS in nondiabetic adults and suggest the relevance of tryptophan metabolites as diagnostic biomarkers.

The beneficial effects of Lactobacillus brevis FZU0713-fermented Laminaria japonica on lipid metabolism and intestinal microbiota in hyperlipidemic rats fed with a high-fat diet

This study aimed to investigate the beneficial effects of the oral administration of Lactobacillus brevis FZU0713-fermented Laminaria japonica (FLJ) on lipid metabolism and intestinal microbiota in hyperlipidemic rats fed with a high-fat diet (HFD). The results demonstrated that the oral administration of FLJ significantly inhibited obesity and improved the serum and hepatic biochemical parameters in HFD-fed rats. Histopathological results also indicated that FLJ intervention could significantly reduce the accumulation of lipid droplets in the liver induced by HFD feeding. Furthermore, FLJ intervention up-regulated the fecal short-chain fatty acid (SCFA) levels (mainly acetate, propionate and isobutyrate) in HFD-fed rats. Intestinal microbiota profiling by 16S rRNA gene sequencing revealed that FLJ intervention increased the relative abundance of Akkermansia, Collinsella, Ruminococcaceae_UCG-013, Defluviitaleaceae_UCG-011, Intestinimonas, Actinomyces and Tyzzerella, but decreased the abundance of Flavonifractor, Collinsella, Sporosarcina and Lacticigenium. Based on Spearman's correlation, the fecal levels of TC, TG, acetic acid and butyric acid were positively correlated with the relative abundance of Akkermansia and Ruminococcaceae_NK4A214, but negatively correlated with the relative amount of Flavonifractor and Collinsella. The metabolic function of intestinal microbiota predicted by PICRUSt analysis of 16S rRNA gene sequences demonstrated that primary and secondary bile acid biosyntheses, fatty acid biosynthesis, taurine and hypotaurine metabolism, arachidonic acid metabolism, glycolysis/gluconeogenesis, etc. were significantly down-regulated after 8 weeks of FLJ intervention. Additionally, FLJ intervention significantly regulated the hepatic mRNA levels (including BSEP, CYP7A1, LDLR, HMGCR, CD36 and SREBP1-C) involved in lipid metabolism and bile acid homeostasis. In conclusion, these findings support the possibility that Laminaria japonica fermented with probiotic Lactobacillus has the potential to reduce the disturbance of lipid metabolism by regulating intestinal microflora and liver gene expression profiles, so it can be employed as a potential functional food to prevent hyperlipidemia.

Salvia-Nelumbinis naturalis extract protects mice against MCD diet-induced steatohepatitis via activation of colonic FXR-FGF15 pathway

Salvia-Nelumbinis naturalis (SNN) formula is a traditional Chinese medicine prescription, and has been confirmed to be effective in treating non-alcoholic steatohepatitis (NASH), but the underlying mechanisms are still unknown. Here we showed that 4-week SNN administration alleviated methionine-choline-deficiency (MCD) diet-induced hepatic steatosis and inflammation as well as serum levels of alanine transaminase (ALT) increase in C57BL/6 mice. Fecal 16S rDNA sequencing indicated that SNN altered the structure of gut microbiota and partially reversed the gut dysbiosis. Simultaneously, we analyzed the fecal BA profile using liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-TQMS) -based metabolomics, and found that SNN modulated fecal BA profile, predominantly increased the microbiomes related BA species (e.g. nordeoxycholic acid) which in turn, activated farnesoid X receptor (FXR)-fibroblast growth factor 15 (FGF15) signaling pathway in the colon but not the ileum. The activation of intestinal FXR-FGF15 signaling was accompanied by increase of liver protein kinase B (PKB/Akt) phosphorylation, and decrease of p-65 subunit of NF-κB phosphorylation, resulting in less liver CD68 positive macrophages, and inflammatory cytokine IL-1β and TNF-α expression. Our results established the link between SNN treatment, gut microbiota, BA profile and NASH, which might shed light into the mechanisms behind the beneficial effects of SNN on NASH, thus provide evidence for the clinical application of SNN.

Soyasaponin A2 Alleviates Steatohepatitis Possibly through Regulating Bile Acids and Gut Microbiota in the Methionine and Choline-Deficient (MCD) Diet-induced Nonalcoholic Steatohepatitis (NASH) Mice

SCOPE

Nonalcoholic steatohepatitis (NASH) is a chronic progressive disease with complex pathogenesis of which the bile acids (BAs) and gut microbiota are involved. Soyasaponins (SS) exhibits many health-promoting effects including hepatoprotection, but its prevention against NASH is unclear. This study aims to investigate the preventive bioactivities of SS monomer (SS-A₂ ) against NASH and further clarify its mechanism by targeting the BAs and gut microbiota.

METHODS AND RESULTS

The methionine and choline deficient (MCD) diet-fed male C57BL/6 mice were intervened with obeticholic acid or SS-A₂ for 16 weeks. Hepatic pathology is assessed by hematoxylin-eosin and Masson's trichrome staining. BAs in serum, liver, and colon are measured by ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-TQMS). Gut microbiota in caecum are determined by 16S rDNA amplicon sequencing. In the MCD diet-induced NASH mice, SS-A₂ significantly reduces hepatic steatosis, lobular inflammation, ballooning, nonalcoholic fatty liver disease activity score (NAS) scores, and fibrosis, decreases Erysipelotrichaceae (Faecalibaculum) and Lactobacillaceae (Lactobacillus) and increases Desulfovibrionaceae (Desulfovibrio). Moreover, SS-A₂ reduces serum BAs accumulation and promotes fecal BAs excretion. SS-A₂ changes the BAs profiles in both liver and serum and specifically increases the taurohyodeoxycholic acid (THDCA) level. Faecalibaculum is negatively correlated with serum THDCA.

CONCLUSION

SS-A₂ alleviates steatohepatitis possibly through regulating BAs and gut microbiota in the MCD diet-induced NASH mice.

Serum metabolomic profiling reveals an increase in homocitrulline in Chinese patients with nonalcoholic fatty liver disease: a retrospective study

Backgrounds

Nonalcoholic fatty liver disease (NAFLD) has multiple causes, is triggered by individual genetic susceptibility, environmental factors, and metabolic disturbances, and may be triggered by acquired metabolic stress. The metabolic profiles of NAFLD show significant ethnic differences, and the metabolic characteristics of NAFLD in Chinese individuals are unclear. Our study aimed to identify the metabolites and pathways associated with NAFLD in a Chinese cohort.

Methods

One hundred participants, including 50 NAFLD patients and 50 healthy controls, were enrolled in this retrospective observational study at Jinling Hospital in Nanjing; serum samples were collected from the patients and healthy subjects. The metabolome was determined in all samples by liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-Q/TOF-MS). Univariate and multivariate statistical analyses were used to compare the metabolic profiles between the two groups.

Results

The comparison indicated that the levels of 89 metabolites were different between the two groups. The glycerophospholipid family of metabolites was the most abundant family of metabolites that demonstrated significant differences. L-acetylcarnitine, L-homocitrulline, and glutamic acid were the top three metabolites ranked by VIP score and had favorable effective functions for diagnosis. Moreover, pathway enrichment analysis suggested 14 potentially different metabolic pathways between NAFLD patients and healthy controls based on their impact value. Biological modules involved in the lipid and carbohydrate metabolism had the highest relevance to the conditions of NAFLD. Glycerophospholipid metabolism had the strongest associations with the conditions of NAFLD.

Conclusions

Our data suggest that the serum metabolic profiles of NAFLD patients and healthy controls are different. L-Homocitrulline was remarkably increased in NAFLD patients.

Extract of Schisandra chinensis fruit protects against metabolic dysfunction in high-fat diet induced obese mice via FXR activation

Schisandra chinensis fruit has been shown to restore carbohydrate- and lipid-metabolic disorders and has anti-hepatotoxicity and anti-hepatitis activities. However, the molecular targets mediating the pharmacological properties of S. chinensis fruit have not been clarified. Here, we assayed the effects of S. chinensis fruit ethanol extract (SCE) on farnesoid X receptor (FXR) transactivity. The pharmacological effects of SCE (1 g/100 g diet) were assessed in high-fat diet (HFD)-fed C57BL/6 mice and ob/ob mice. The FXR and Fgf15 signalling pathways were evaluated by FXR silencing, ELISA, Western blot and RT-PCR analyses. The results showed that SCE treatment increased FXR transcription activity and improved obesity, hypercholesteremia and fatty liver in HFD-fed mice, while it had limited effects on ob/ob mice. Our study suggests that SCE treatment may improve HFD-induced metabolic disorders through pharmacological activation of FXR/Fgf15 signalling, and such beneficial effects of SCE may require leptin participation.

The Gut Microbiota and Its Metabolites, Novel Targets for Treating and Preventing Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent metabolic disorders worldwide, along with obesity and type 2 diabetes. NAFLD involves a series of liver abnormalities from simple hepatic steatosis to non-alcoholic steatohepatitis, which can ultimately lead to liver cirrhosis and cancer. The gut-liver axis plays an important role in the development of NAFLD, which depends mainly on regulation of the gut microbiota and its bacterial products. These intestinal bacterial species and their metabolites, including bile acids, tryptophan catabolites, and branched-chain amino acids, regulate adipose tissue and intestinal homeostasis and contribute to the pathogenesis of NAFLD/non-alcoholic steatohepatitis. In this review, the current evidence regarding the key role of the gut microbiota and its metabolites in the pathogenesis and development of NAFLD is highlighted, and the advances in the progression and applied prospects of gut microbiota-targeted dietary and exercise therapies is also discussed.

Ganoderic acid A from Ganoderma lucidum ameliorates lipid metabolism and alters gut microbiota composition in hyperlipidemic mice fed a high-fat diet

Ganoderic acid A (GA) is one of the most abundant triterpenoids in Ganoderma lucidum, and has been proved to possess a wide range of beneficial health effects. The aim of the current study is to investigate the amelioration effects and mechanism of GA on improving hyperlipidemia in mice fed a high-fat diet (HFD). The results showed that GA intervention significantly inhibited the abnormal growth of body weight and epididymal white adipose tissue (eWAT), prevented the hypertrophy of epididymal adipocytes, and ameliorated the biochemical parameters of serum and liver related to lipid metabolism in HFD-fed mice. Histological analysis also showed that the excessive accumulation of lipid droplets in the liver induced by HFD-feeding was greatly alleviated by GA intervention. In addition, GA intervention also increased the level of short chain fatty acids (SCFAs) in the intestine and promoted the excretion of bile acids (BAs) through feces. High-throughput sequencing of bacterial full-length 16S rDNA revealed that daily supplementation with GA made significant structural changes in the gut microbial population of mice fed with HFD, in particular modulating the relative abundance of some function related microbial phylotypes. The relationships between lipid metabolic parameters and gut microbial phylotypes were also revealed by correlation analysis based on a heatmap and network. The result showed that 46 key gut microbial phylotypes (OTUs) were markedly correlated with at least one lipid metabolic parameter. Moreover, UPLC-QTOF/MS-based liver metabolomics showed that 111 biomarkers (47 up-regulated metabolites and 64 down-regulated metabolites) were significantly changed after high-dose GA intervention (75 mg kg^-1 day^-1), compared with the HFD-fed hyperlipidemic mice. Metabolic pathway enrichment analysis of the differential hepatic metabolites demonstrated that GA intervention had significant regulatory effects on primary bile acid biosynthesis, fatty acid biosynthesis, amino sugar and nucleotide sugar metabolism, inositol phosphate metabolism, and so on. In addition, GA intervention regulated the mRNA levels of hepatic genes involved in fatty acid metabolism and bile acid homeostasis. These findings present new evidence supporting that GA from G. lucidum has the potential to alleviate lipid metabolic disorders and ameliorate the imbalance of gut microflora in a positive way.

Protective Mechanism of Common Buckwheat (Fagopyrum esculentum Moench.) against Nonalcoholic Fatty Liver Disease Associated with Dyslipidemia in Mice Fed a High-Fat and High-Cholesterol Diet

This study aimed to investigate the protective mechanism of common buckwheat (Fagopyrum esculentum Moench.) against nonalcoholic fatty liver disease (NAFLD) associated with dyslipidemia in mice that were fed a high-fat and high-cholesterol diet (HFD). Results showed that oral supplementation of common buckwheat significantly improved physiological indexes and biochemical parameters related to dyslipidemia and NAFLD in mice fed with HFD. Furthermore, the HFD-induced reductions in fecal short-chain fatty acids were reversed by common buckwheat intervention, which also increased the fecal bile acid (BA) abundance compared with HFD-induced hyperlipidemic mice. Liver metabolomics based on ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry demonstrated that common buckwheat supplementation made significant regulatory effects on the pentose phosphate pathway, starch and sucrose metabolism, primary BA biosynthesis, and so forth. The results of high-throughput sequencing revealed that common buckwheat supplementation significantly altered the structure of the intestinal microbiota in mice fed with HFD. The correlations between lipid metabolic parameters and intestinal microbial phylotypes were also revealed by the heatmap and network. Additionally, common buckwheat intervention regulated the mRNA expressions of genes responsible for liver lipid metabolism and BA homeostasis, thus promoting BA synthesis and excretion. These findings confirmed that common buckwheat has the outstanding ability of improving lipid metabolism and could be used as a potential functional food for the prevention of NAFLD and hyperlipidemia.

Supplemental Clostridium butyricum Modulates Lipid Metabolism Through Shaping Gut Microbiota and Bile Acid Profile of Aged Laying Hens

Probiotic Clostridium butyricum could affect lipid metabolism in broilers. However, it is not clear whether C. butyricum could improve lipid metabolism through shaping gut microbiota and bile acid (BA) profile of laying hens. We aimed to evaluate the contributions of gut microbiota and BA profile to the potential effect of C. butyricum on lipid metabolism of aged laying hens. A total of 192 60-week-old Hy-Line Brown laying hens were divided into two groups (eight replicates per group). Birds were fed a basal diet supplemented with 0 or 2.7 g/kg C. butyricum (1.0 × 10⁹ CFU/g). Samples were collected at the end of week 8 of the experiment. The results showed elevated (P < 0.05) concentrations of glucagon-like peptide 1, insulin and thyroid hormones in serum responded to C. butyricum addition, which also decreased (P < 0.05) hepatic free fatty acids contents, as well as increased (P < 0.05) the expression of hepatic acyl-CoA oxidase, farnesoid X receptor (FXR) and PPARα. C. butyricum addition increased (P < 0.05) Bacteroidetes abundance but tended to decrease (P < 0.10) Firmicutes abundance in the ileum. Besides, C. butyricum addition resulted in higher (P < 0.05) abundances of Clostridia (Clostridiales) and Prevotellaceae, concurrent with an increasing trend (P < 0.10) of Bifidobacteriaceae abundance and decreased the abundances of several harmful bacteria such as Klebsiella (P < 0.05). Regarding ileal BA profile, there was a reduced (P < 0.05) content of tauro-α-muricholic acid, increased (P < 0.05) contents of tauroursodeoxycholic acid and lithocholic acid, along with increasing trends (P < 0.10) of glycochenodeoxycholic acid and hyodeoxycholic acid contents due to C. butyricum addition, which also increased (P < 0.05) ileal FXR expression. Collectively, supplemental C. butyricum accelerated hepatic fatty acid oxidation, and shaped gut microbiota and BA profile, thus reducing fat deposition in the liver of aged laying hens.

Metabolomic and Lipidomic Biomarkers for Premalignant Liver Disease Diagnosis and Therapy

In recent years, there has been a plethora of attempts to discover biomarkers that are more reliable than α-fetoprotein for the early prediction and prognosis of hepatocellular carcinoma (HCC). Efforts have involved such fields as genomics, transcriptomics, epigenetics, microRNA, exosomes, proteomics, glycoproteomics, and metabolomics. HCC arises against a background of inflammation, steatosis, and cirrhosis, due mainly to hepatic insults caused by alcohol abuse, hepatitis B and C virus infection, adiposity, and diabetes. Metabolomics offers an opportunity, without recourse to liver biopsy, to discover biomarkers for premalignant liver disease, thereby alerting the potential of impending HCC. We have reviewed metabolomic studies in alcoholic liver disease (ALD), cholestasis, fibrosis, cirrhosis, nonalcoholic fatty liver (NAFL), and nonalcoholic steatohepatitis (NASH). Specificity was our major criterion in proposing clinical evaluation of indole-3-lactic acid, phenyllactic acid, N-lauroylglycine, decatrienoate, N-acetyltaurine for ALD, urinary sulfated bile acids for cholestasis, cervonoyl ethanolamide for fibrosis, 16α-hydroxyestrone for cirrhosis, and the pattern of acyl carnitines for NAFL and NASH. These examples derive from a large body of published metabolomic observations in various liver diseases in adults, adolescents, and children, together with animal models. Many other options have been tabulated. Metabolomic biomarkers for premalignant liver disease may help reduce the incidence of HCC.

Salidroside improves high-fat diet-induced non-alcoholic steatohepatitis by regulating the gut microbiota-bile acid-farnesoid X receptor axis

BACKGROUND

Our previous studies found that salidroside can effectively treat non-alcoholic steatohepatitis (NASH). Here, we discuss the mechanism of salidroside in the treatment of NASH with a focus on the gut microbiota-bile acid-farnesoid X receptor axis.

METHODS

A NASH mouse model was created by providing mice with a high-fat diet (HFD) for 14 weeks. Mice were randomly divided into the HFD group, HFD + salidroside treatment group, and HFD + obeticholic acid treatment group (n = 8 in each group) and were intragastrically administered corresponding drugs for 4 weeks. Hematoxylin-eosin staining was performed to evaluate the histopathological changes associated with the various treatments. In addition, liver triglyceride (TG) content, serum alanine aminotransferase (ALT) activity, serum inflammatory factors, gut microbiota diversity, and the bile acid profile were evaluated. Western blotting and RT-PCR were performed to detect the expressions of FXR and fibroblast growth factor 15 (FGF15).

RESULTS

The HFD group displayed obvious signs of hepatic steatosis. The liver TG, serum ALT, and IL-1a, IL-12, MCP-1, KC, MIP-1a, and MIP-1β were significantly higher in the HFD group than the control group (P < 0.01). Intestinal bacteria and bile acid profiles changed significantly in the HFD group (P < 0.05). Further, the expressions of FXR and FGF15 decreased significantly in the HFD group (P < 0.05). After treatment with salidroside, liver steatosis, TG content, and serum inflammatory factors significantly improved and HFD-induced intestinal bacteria, bile acid disorder, and FXR deficiency were significantly alleviated (P < 0.05).

CONCLUSION

Salidroside can improve NASH via the gut microbiota-bile acid-FXR axis.

Relationship between Changes in Microbiota and Liver Steatosis Induced by High-Fat Feeding-A Review of Rodent Models

Several studies have observed that gut microbiota can play a critical role in nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) development. The gut microbiota is influenced by different environmental factors, which include diet. The aim of the present review is to summarize the information provided in the literature concerning the impact of changes in gut microbiota on the effects which dietary fat has on liver steatosis in rodent models. Most studies in which high-fat feeding has induced steatosis have reported reduced microbiota diversity, regardless of the percentage of energy provided by fat. At the phylum level, an increase in Firmicutes and a reduction in Bacteroidetes is commonly found, although widely diverging results have been described at class, order, family, and genus levels, likely due to differences in experimental design. Unfortunately, this fact makes it difficult to reach clear conclusions concerning the specific microbiota patterns associated with this feeding pattern. With regard to the relationship between high-fat feeding-induced changes in liver and microbiota composition, although several mechanisms such as alteration of gut integrity and increased permeability, inflammation, and metabolite production have been proposed, more scientific evidence is needed to address this issue and thus further studies are needed.