Hepatocyte CHRNA4 mediates the MASH-promotive effects of immune cell-produced acetylcholine and smoking exposure in mice and humans.

Metabolic dysfunction-associated steatohepatitis (MASH) is a leading risk factor for liver cirrhosis and hepatocellular carcinoma. Here, we report that CHRNA4, a subunit of nicotinic acetylcholine receptors (nAChRs), is an accelerator of MASH progression. CHRNA4 also mediates the MASH-promotive effects induced by smoking. Chrna4 was expressed specifically in hepatocytes and exhibited increased levels in mice and patients with MASH. Elevated CHRNA4 levels were positively correlated with MASH severity. We further revealed that during MASH development, acetylcholine released from immune cells or nicotine derived from smoking functioned as an agonist to activate hepatocyte-intrinsic CHRNA4, inducing calcium influx and activation of inflammatory signaling. The communication between immune cells and hepatocytes via the acetylcholine-CHRNA4 axis led to the production of a variety of cytokines, eliciting inflammation in liver and promoting the pathogenesis of MASH. Genetic and pharmacological inhibition of CHRNA4 protected mice from diet-induced MASH. Targeting CHRNA4 might be a promising strategy for MASH therapeutics.

Alcohol drinking alters oral microbiota to modulate the progression of alcohol-related liver disease.

Alcohol-related liver disease (ALD) is one of the leading causes of liver-related death worldwide. However, roles of oral microbiota in regulating the progression of ALD remain unknown. Here, we fed mice with control or ethanol diet to establish chronic-plus-binge ALD model. 16S ribosomal DNA sequencing was performed on oral and cecum samples. We demonstrated that alcohol drinking influenced bacterial richness, microbial structure, and composition in oral samples of ethanol-fed mice compared with control mice. Alcohol consumption also remodeled relationships among oral microbes and altered functions of oral microbiota. Furthermore, oral microbiota, such as Streptococcus, Helicobacter, Alloprevotella, and Psychrobacter were closely associated with ALD parameters. Finally, we observed Sutterellaceae_uncultured, Dyella, and Gemmatimonas possibly translocated along with oral-gut axis and positively correlated with the severity of ALD. Altogether, alcohol consumption reprogramed composition and functions of oral microbiota to promote ALD progression, suggesting that oral microbes might become a new target for ALD therapy.

Amlodipine, an anti-hypertensive drug, alleviates non-alcoholic fatty liver disease by modulating gut microbiota.

BACKGROUND AND PURPOSE: Non-alcoholic fatty liver disease (NAFLD) represents a severe public health problem. It often coexists with hypertension in the context of metabolic syndrome. We investigated the effects of amlodipine on NAFLD combined with hypertension and investigated the underlying mechanism/s. EXPERIMENTAL APPROACH: Mice were fed with high-fat diet (HFD) and 0.05% N-nitro-L-arginine methylester sterile water to induce NAFLD with hypertension. Gut microbiota composition and function were assessed by 16S ribosomal DNA and metagenomic sequencing. Untargeted metabolome profiles were applied to identify differential metabolites in mice caecum. KEY RESULTS: Amlodipine besylate and amlodipine aspartate significantly decreased liver injury and hepatic steatosis, and improved lipid metabolism with a concomitant reduction in the expression of lipogenic genes in mice with NAFLD and hypertension. Mechanistically, amlodipine besylate and amlodipine aspartate have potential to restore intestinal barrier integrity and improve antimicrobial defence, along with the elevated abundances of Akkermansia, Bacteroides and Lactobacillus. Noteworthily, the gut microbiota in amlodipine besylate- and amlodipine aspartate-treated mice had higher abundance of functional genes involved in taurine and hypotaurine metabolism. Consistently, the strengthened taurine and hypotaurine metabolism was confirmed by untargeted metabolome analysis. Based on the correlation and causal analysis, the altered gut microbiota composition and the enhancement of taurine and hypotaurine metabolism may synergistically decreased alanine aminotransferase, liver triglycerides, lipogenic genes and plasma cholesterol in HFD-fed hypertensive mice. CONCLUSION AND IMPLICATIONS: Amlodipine besylate and amlodipine aspartate exert multifactorial improvements in NAFLD and hypertension by modulating gut microbiota. They may serve as promising therapeutic agents for treating these diseases.

Aryl Hydrocarbon Receptor Deficiency in Intestinal Epithelial Cells Aggravates Alcohol-Related Liver Disease.

BACKGROUND & AIMS: The ligand-activated transcription factor, aryl hydrocarbon receptor (AHR) can sense xenobiotics, dietary, microbial, and metabolic cues. Roles of Ahr in intestinal epithelial cells (IECs) have been much less elucidated compared with those in intestinal innate immune cells. Here, we explored whether the IEC intrinsic Ahr could modulate the development of alcohol-related liver disease (ALD) via the gut-liver axis. METHODS: Mice with IEC specific Ahr deficiency (AhrΔIEC) were generated and fed with a control or ethanol diet. Alterations of intestinal microbiota and metabolites were investigated by 16S ribosomal RNA sequencing, metagenomics, and untargeted metabolomics. AHR agonists were used to evaluate the therapeutic potentials of intestinal Ahr activation for ALD treatment. RESULTS: AhrΔIEC mice showed more severe liver injury after ethanol feeding than control mice. Ahr deficiency in IECs altered the intestinal metabolite composition, creating an environment that promoted the overgrowth of Helicobacter hepaticus and Helicobacter ganmani in the gut, enhancing their translocation to mesenteric lymph nodes and liver. Among the altered metabolites, isobutyric acid was increased in the cecum of ethanol-fed AhrΔIEC mice relative to control mice. Furthermore, both H.hepaticus and isobutyric acid administration aggravated ethanol-induced liver injury in vivo and in vitro. Supplementation with AHR agonists, 6-formylindolo[3,2-b]carbazole and indole-3-carbinol, protected mice from ALD development by specifically activating intestinal Ahr without affecting liver Ahr function. Alcoholic patients showed lower intestinal AHR expression and higher H.hepaticus levels compared with healthy individuals. CONCLUSIONS: Our results indicate that targeted restoration of IEC intrinsic Ahr function may present as a novel approach for ALD treatment.

Intestinal α1-2-Fucosylation Contributes to Obesity and Steatohepatitis in Mice.

BACKGROUND & AIMS: Fucosyltransferase 2 (Fut2)-mediated intestinal α1- 2-fucosylation is important for host-microbe interactions and has been associated with several diseases, but its role in obesity and hepatic steatohepatitis is not known. The aim of this study was to investigate the role of Fut2 in a Western-style diet-induced mouse model of obesity and steatohepatitis. METHODS: Wild-type (WT) and Fut2-deficient littermate mice were used and features of the metabolic syndrome and steatohepatitis were assessed after 20 weeks of Western diet feeding. RESULTS: Intestinal α1-2-fucosylation was suppressed in WT mice after Western diet feeding, and supplementation of α1-2-fucosylated glycans exacerbated obesity and steatohepatitis in these mice. Fut2-deficient mice were protected from Western diet-induced features of obesity and steatohepatitis despite an increased caloric intake. These mice have increased energy expenditure and thermogenesis, as evidenced by a higher core body temperature. Protection from obesity and steatohepatitis associated with Fut2 deficiency is transmissible to WT mice via microbiota exchange; phenotypic differences between Western diet-fed WT and Fut2-deficient mice were reduced with antibiotic treatment. Fut2 deficiency attenuated diet-induced bile acid accumulation by altered relative abundance of bacterial enzyme 7-α-hydroxysteroid dehydrogenases metabolizing bile acids and by increased fecal excretion of secondary bile acids. This also was associated with increased intestinal farnesoid X receptor/fibroblast growth factor 15 signaling, which inhibits hepatic synthesis of bile acids. Dietary supplementation of α1-2-fucosylated glycans abrogates the protective effects of Fut2 deficiency. CONCLUSIONS: α1-2-fucosylation is an important host-derived regulator of intestinal microbiota and plays an important role for the pathogenesis of obesity and steatohepatitis in mice.

Coordinated changes of gut microbiome and lipidome differentiates nonalcoholic steatohepatitis (NASH) from isolated steatosis.

BACKGROUND & AIMS: Nonalcoholic fatty liver disease encompasses isolated steatosis or nonalcoholic fatty liver and nonalcoholic steatohepatitis (NASH). NASH develops from isolated steatosis with obscure driving forces. We aim to identify key factors promoting this transition. METHODS: Following 21-week of high-fat diet feeding, obese mice were classified into two groups termed as isolated steatosis and NASH based on hematoxylin-eosin staining of liver histology. The integrated multi-omics analysis of lipidome, transcriptome and gut microbiome were performed in mice with isolated steatosis and NASH, and confirmed in human samples. RESULTS: Livers in mice with NASH lost most lipids, and the transcriptional landscape was also changed dramatically in mice with NASH in relative to mice with isolated steatosis. Plasma lipidome analysis demonstrated a very clear difference between these two groups of mice, which was partially recapitulated in serum of patients with isolated steatosis and NASH. The microbiota composition revealed that Bacteroides genus and Bacteroides uniformis species decreased while Mucispirillum genus and Mucispirillum schaedleri species increased largely in mice with NASH. More importantly, we found that Bacteroides uniformis correlated positively with triglycerides (TGs) and negatively with free fatty acids (FFAs) and PE(18:1/20:4), while Mucispirillum schaedleri correlated positively with FFAs, LysoPC(20:3), LysoPC(20:4) and DG(16:1/18:2). Mechanically, administration of Bacteroides uniformis increased specific TGs, and decreased hepatic injury and inflammation in diet-induced mice. CONCLUSIONS: Overall, through multi-omics integration, we identified a microbiota-lipid axis promoting the initiation of NASH from isolated steatosis, which might provide a novel perspective on NASH pathogenesis and treatment.

WZ66, a novel acetyl-CoA carboxylase inhibitor, alleviates nonalcoholic steatohepatitis (NASH) in mice.

The global prevalence of nonalcoholic steatohepatitis (NASH) increases incredibly. NASH ends up to advanced liver disease, which is highly threatening to human health. Currently, treatment of NASH is very limited. Acetyl-CoA carboxylases (ACC1/ACC2) are proved as effective drug targets for NASH. We aimed to develop novel ACC inhibitors and evaluate their therapeutic value for NASH prevention. ACC inhibitors were obtained through structure-based drug design, synthesized, screened from ACC enzymatic measurement platform and elucidated in cell culture-based assays and animal models. The lipidome and microbiome analysis were integrated to assess the effects of WZ66 on lipids profiles in liver and plasma as well as gut microbiota in the intestine. WZ66 was identified as a novel ACC1/2 inhibitor. It entered systemic circulation rapidly and could accumulate in liver. WZ66 alleviated NASH-related liver features including steatosis, Kupffer cells and hepatic stellate cells activation in diet-induced obese mice. The triglycerides (TGs) and other lipids including diglycerides (DGs), phosphatidylcholine (PC) and sphingomyelin (SM) were decreased in WZ66-treated mice as evidenced by lipidome analysis in livers. The lipids profiles in plasma were also altered with WZ66 treatment. Plasma TG were moderately increased, while the activation of SREBP1c was not detected. WZ66 also downregulated the abundance of Allobaculum, Mucispirillum and Prevotella genera as well as Mucispirillum schaedleri species in gut microbiota. WZ66 is an ideal lead compound and a potential drug candidate deserving further investigation in the therapeutics of NASH.

YIPF6 controls sorting of FGF21 into COPII vesicles and promotes obesity.

Fibroblast growth factor 21 (FGF21) is an endocrine hormone that regulates glucose, lipid, and energy homeostasis. While gene expression of FGF21 is regulated by the nuclear hormone receptor peroxisome proliferator-activated receptor alpha in the fasted state, little is known about the regulation of trafficking and secretion of FGF21. We show that mice with a mutation in the Yip1 domain family, member 6 gene (Klein-Zschocher [KLZ]; Yipf6KLZ/Y ) on a high-fat diet (HFD) have higher plasma levels of FGF21 than mice that do not carry this mutation (controls) and hepatocytes from Yipf6KLZ/Y mice secrete more FGF21 than hepatocytes from wild-type mice. Consequently, Yipf6KLZ/Y mice are resistant to HFD-induced features of the metabolic syndrome and have increased lipolysis, energy expenditure, and thermogenesis, with an increase in core body temperature. Yipf6KLZ/Y mice with hepatocyte-specific deletion of FGF21 were no longer protected from diet-induced obesity. We show that YIPF6 binds FGF21 in the endoplasmic reticulum to limit its secretion and specifies packaging of FGF21 into coat protein complex II (COPII) vesicles during development of obesity in mice. Levels of YIPF6 protein in human liver correlate with hepatic steatosis and correlate inversely with levels of FGF21 in serum from patients with nonalcoholic fatty liver disease (NAFLD). YIPF6 is therefore a newly identified regulator of FGF21 secretion during development of obesity and could be a target for treatment of obesity and NAFLD.

Chitosan Oligosaccharide Ameliorates Nonalcoholic Fatty Liver Disease (NAFLD) in Diet-Induced Obese Mice.

Nonalcoholic fatty liver disease (NAFLD) is a global epidemic, and there is no standard and efficient therapy for it. Chitosan oligosaccharide (COS) is widely known to have various biological effects, and in this study we aimed to evaluate the liver-protective effect in diet-induced obese mice for an enzymatically digested product of COS called COS23 which is mainly composed of dimers and trimers. An integrated analysis of the lipidome and gut microbiome were performed to assess the effects of COS23 on lipids in plasma and the liver as well as on intestinal microbiota. Our results revealed that COS23 obviously attenuated hepatic steatosis and ameliorated liver injury in diet-induced obese mice. The hepatic toxic lipids-especially triglycerides (TGs) and free fatty acids (FFAs)-were decreased dramatically after COS23 treatment. COS23 regulated lipid-related pathways, especially inhibiting the expressions of FFA-synthesis-related genes and inflammation-related genes. Furthermore, COS23 could alter lipid profiles in plasma. More importantly, COS23 also decreased the abundance of Mucispirillum and increased the abundance of Coprococcus in gut microbiota and protected the intestinal barrier by up-regulating the expression of tight-junction-related genes. In conclusion, COS23, an enzymatically digested product of COS, might serve as a promising candidate in the clinical treatment of NAFLD.

Flavonoid VI-16 protects against DSS-induced colitis by inhibiting Txnip-dependent NLRP3 inflammasome activation in macrophages via reducing oxidative stress.

Emerging evidence suggests that NLRP3 inflammasome was associated with various kinds of immunological diseases including colitis. However, there are few drugs targeting inflammasomes in the treatment of colitis. Several flavonoids have been found to affect the inflammasome pathway, but the mechanism is still confusing. Here we report that VI-16, a synthetic flavonoid compound, exerts potent anti-inflammatory effects on macrophages in DSS-induced colitis mice, which intervened in the activation of NLRP3 inflammasome without affecting intestinal epithelial cells. However, the protection of VI-16 against DSS-induced colitis was dependent on NLRP3 expression in hematopoietic cells. Furthermore, this inhibitory effect of VI-16 was found to be at least partially achieved by decreasing the mitochondrial ROS generation without affecting autophagy. Further studies confirm that VI-16 inhibits the binding of Txnip to NLRP3 by reducing oxidative stress and ultimately inhibits NLRP3 inflammasome. This demonstrates the ability of VI-16 to inhibit the NLRP3 inflammasome activation and its potential use in the treatment of inflammatory bowel disease.

Role of Gut Microbiota in the Pharmacological Effects of Natural Products.

Increasing evidence has demonstrated that natural products derived from traditional Chinese medicine, such as ginseng, berberine, and curcumin, possess a wide variety of biological activities on gut microbiota, which may cause changes in the composition of intestinal microbiota, microbial metabolites, intestinal tight junction structure, and mucosal immunology. These changes will eventually result in the exertion of the pharmacological effects by treatment with these natural products. In this review, we will discuss how gut microbiota is influenced by commonly used natural products. Furthermore, our findings are expected to provide novel insight into how these untargeted natural products function via gut microbiota.

Small molecule GL-V9 protects against colitis-associated colorectal cancer by limiting NLRP3 inflammasome through autophagy.

Emerging evidence suggests that NLRP3 inflammasome provides a link between colitis-associated colorectal cancer and inflammatory bowel diseases. Autophagy is induced in macrophages by AMPK activation and regulates NLRP3 inflammasome to maintain intracellular homeostasis. Here we report that a small-molecule AMPK activator (GL-V9) exerts potent anti-inflammatory effects on macrophages invitro and in vivo, which trigger autophagy to degraded NLRP3 inflammasome. Treatment with GL-V9 protected against colitis and tumorigenesis in colitis-associated colorectal cancer. This suggests that GL-V9 may be an interesting candidate for clinical evaluation in the treatment of colitis-associated colorectal cancer.