Depletion of Gut Microbiota Impairs Gut Barrier Function and Antiviral Immune Defense in the Liver

Microbiome and metabolome analyses indicate variations in the gut microbiota that disrupt regulation of appetite

The mechanism connecting gut microbiota to appetite regulation is not yet fully understood. This study identifies specific microbial community and metabolites that may influence appetite regulation. In the initial phase of the study, mice were administered a broad-spectrum antibiotic cocktail (ABX) for 10 days. The treatment significantly reduced gut microbes and disrupted the metabolism of arginine and tryptophan. Consequently, ABX-treated mice demonstrated a notable reduction in feed consumption. The hypothalamic expression levels of CART and POMC, two key anorexigenic factors, were significantly increased, while orexigenic factors, such as NPY and AGRP, were decreased. Notably, the levels of appetite-suppressing hormone cholecystokinin in the blood were significantly elevated. In the second phase, control mice were maintained, while the ABX-treated mice received saline, probiotics, and short-chain fatty acids (SCFAs) for an additional 10 days to restore their gut microbiota. The microbiota reconstructed by probiotic and SCFA treatments were quite similar, while microbiota of the naturally recovering mice demonstrated greater resemblance to that of the control mice. Notably, the abundance of Akkermansia and Bacteroides genera significantly increased in the reconstructed microbiota. Moreover, microbiota reconstruction corrected the disrupted arginine and tryptophan metabolism and the abnormal peripheral hormone levels caused by ABX treatment. Among the groups, SCFA-treated mice had the highest feed intake and NPY expression. Our findings indicate that gut microbes, especially Akkermansia, regulate arginine and tryptophan metabolism, thereby influencing appetite through the microbe-gut-brain axis.

A Mendelian randomization study investigating causal links between gut microbiota or metabolites and chronic hepatitis B

Objective

This study aimed to explore the potential causal relationship between the gut microbiota and/or its metabolites and the progression of chronic hepatitis B (CHB).

Method

The gut microbiota was used as the exposure factor. The training set exposure data were obtained from the China Nucleotide Sequence Archive (CNSA). Genome-wide association study (GWAS) data from Asia were used as the outcome variables. Outcome data for both the training and validation sets were sourced from the GWAS Catalog database. A dual-sample Mendelian randomization approach was used to analyze the causal relationships, with the inverse variance-weighted method serving as the main analytical strategy. Sensitivity analysis was conducted to assess the robustness of Mendelian randomization analysis results.

Result

In the training set database, analysis using the inverse variance-weighted method revealed a positive correlation between Fusobacterium varium and chronic hepatitis B [OR = 1.122, 95% CI (1.016, 1.240), p = 0.022]. Conversely, Veillonella parvula exhibited a negative correlation with chronic hepatitis B [OR = 0.917, 95% CI (0.852, 0.987), p = 0.021]. Sensitivity analysis revealed no evidence of pleiotropy and heterogeneity. No gut microbiota metabolites with a causal effect on chronic hepatitis B were identified. Additionally, no associations between the gut microbiota and the progression of chronic hepatitis B were found in the validation data from the European cohort.

Conclusion

This study suggests that F. varium may facilitate the progression of chronic hepatitis B, whereas V. parvula may impede it. No causal relationships between gut microbiota metabolites and chronic hepatitis B were established.

The oral-gut microbiome axis in health and disease

The human body hosts trillions of microorganisms throughout many diverse habitats with different physico-chemical characteristics. Among them, the oral cavity and the gut harbour some of the most dense and diverse microbial communities. Although these two sites are physiologically distinct, they are directly connected and can influence each other in several ways. For example, oral microorganisms can reach and colonize the gastrointestinal tract, particularly in the context of gut dysbiosis. However, the mechanisms of colonization and the role that the oral microbiome plays in causing or exacerbating diseases in other organs have not yet been fully elucidated. Here, we describe recent advances in our understanding of how the oral and intestinal microbiota interplay in relation to their impact on human health and disease.

Potential Probiotic Weizmannia coagulans WC10 Improved Antibiotic-Associated Diarrhea in Mice by Regulating the Gut Microbiota and Metabolic Homeostasis

Antibiotic-associated diarrhea (AAD) is a common side effect of long-term and heavy antibiotic therapy. Weizmannia coagulans (W. coagulans) is an ideal probiotic because of its high viability, stability, and numerous health benefits to the host. In this study, the strains were first screened for W. coagulans WC10 (WC10) with a high combined ability based on their biological properties of gastrointestinal tolerance, adhesion, and short-chain fatty acid production ability. The effect of WC10 on mice with AAD was further evaluated. The results showed that WC10 was effective in improving the symptoms of AAD, effectively restoring antibiotic-induced weight loss, and reducing diarrhea status score and fecal water content. In addition, WC10 decreased the expression of pro-inflammatory cytokines and increased the expression of anti-inflammatory cytokines, alleviated intestinal tissue damage and inflammation, and improved intestinal epithelial barrier function by decreasing serum levels of enterotoxin, DAO, and D-lactic acid, and by increasing the expression of the intestinal mucosal immune factors sIgA and occludin. Importantly, the composition and function of the gut microbiota gradually recovered after WC10 treatment, increasing the number of SCFAs-producing Bifidobacterium and Roseburia. Subsequently, the short-chain fatty acid (SCFA) content was examined and WC10 significantly increased acetate, propionate, and butyrate production. Additionally, metabolomic analysis also showed that WC10 reversed the antibiotic interference with major metabolic pathways. These findings provide a solid scientific basis for the future application of W. coagulans WC10 in the treatment of AAD.

Antibiotic administration aggravates asthma by disrupting gut microbiota and the intestinal mucosal barrier in an asthma mouse model

In humans, gut microbiota can determine the health status. The regulatory mechanisms of the gut microbiota in asthma must be elucidated. Although antibiotics (ABXs) can clear infections, they markedly alter the composition and abundance of gut microbiota. The present study used ABX-treated mice to examine the time-dependent effects of ABX administration on the gut microbiota and intestinal mucosal barrier. The mouse asthma model was established using ovalbumin (OVA) and gavaged with an ABX cocktail for different durations (1 or 2 weeks) and stacked sequences. The pathology of the model, model 2, OVA-ABX, OVA-ABX 2, ABX-OVA and ABX-OVA was severe when compared with the control group as evidenced by the following results: i) significantly increased pulmonary and colonic inflammatory cell infiltration; ii) enhanced pause values and iii) OVA-induced immunoglobulin E (IgE) and TGF-β expression levels, and significantly downregulated Tight Junction Protein 1 (TJP1), claudin 1 and Occludin expression levels. Furthermore, the intestinal bacterial load in the OVA-ABX and OVA-ABX 2 groups was significantly lower than that in the ABX-OVA and ABX-OVA 2 groups, respectively. The predominant taxa were as follows: phyla, Firmicutes and Proteobacteria, genera, Escherichia-Shigella, Lactobacillus and Lachnospira. The abundances of Lachnospira and Escherichia-Shigella were correlated with the expression of OVA-induced IgE and TJPs. These findings indicated that ABX administration, which modifies microbiome diversity and bacterial abundance, can disrupt colonic integrity, downregulate TJ proteins, damage the intestinal barrier, enhance enterocyte permeability, and promote the release of inflammatory factors, adversely affecting asthma alleviation and long-term repair.

Lycium barbarum Polysaccharides Improved Glucose Metabolism in Prediabetic Mice by Regulating Duodenal Contraction

Lycium barbarum polysaccharides (LBPs) have been shown to exert an antiglycemic effect. Emerging evidence suggests that patients with hyperglycemia have a hypercontractility of duodenum, and targeting duodenal contraction of duodenum can be beneficial to glucose metabolism. However, it is unknown whether LBPs can improve glucose metabolism by regulating the hypercontractility of the duodenum. Our aim was to explore the effect of LBPs on duodenal contraction in prediabetic mice and also preliminarily investigate the mechanism. The results showed that LBPs improved glucose homeostasis by decreasing the duodenal amplitude of contraction rather than frequency. Moreover, LBPs ameliorated the gut microbiota composition and the levels of short-chain fatty acids, especially acetic acid, which might bind to the receptor on neurons to regulate the contraction of the duodenum. Acetic acid was hypothesized to play a key role in the above process. Then, acetic acid was determined to exert an antiglycemic effect as expected. In conclusion, LBPs may rely on acetic acid to regulate duodenal contraction to ameliorate glucose metabolism in prediabetic mice, which provides a new therapeutic strategy to treat dysglycemia.

Harnessing Autophagy to Overcome Antigen-Specific T-Cell Dysfunction: Implication for People Living with HIV-1

Like other chronic viral infections, HIV-1 persistence inhibits the development of antigen-specific memory T-cells, resulting in the exhaustion of the immune response and chronic inflammation. Autophagy is a major lysosome-dependent mechanism of intracellular large-target degradation such as lipid and protein aggregates, damaged organelles, and intracellular pathogens. Although it is known that autophagy may target HIV-1 for elimination, knowledge of its function as a metabolic contributor in such viral infection is only in its infancy. Recent data show that elite controllers (EC), who are HIV-1-infected subjects with natural and long-term antigen (Ag)-specific T-cell protection against the virus, are characterized by distinct metabolic autophagy-dependent features in their T-cells compared to other people living with HIV-1 (PLWH). Despite durable viral control with antiretroviral therapy (ART), HIV-1-specific immune dysfunction does not normalize in non-controller PLWH. Therefore, the hypothesis of inducing autophagy to strengthen their Ag-specific T-cell immunity against HIV-1 starts to be an enticing concept. The aim of this review is to critically analyze promises and potential limitations of pharmacological and dietary interventions to activate autophagy in an attempt to rescue Ag-specific T-cell protection among PLWH.

Infectious Agents Induce Wnt/β-Catenin Pathway Deregulation in Primary Liver Cancers

Interaction between infectious agents and liver tissue, as well as repeated and extreme biological events beyond adaptive capacities, may result in pathological conditions predisposing people to development of primary liver cancers (PLCs). In adults, PLCs mainly comprise hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). Various infectious agents in the hepatic microenvironment can destabilize normal liver cell functions by modulating the Wnt/β-catenin pathway components. Among them, hepatotropic viruses B, C, and D are involved in Wnt/β-catenin signaling dysregulation. Other microbial agents, including oncogenic viruses such as Epstein-Barr virus (EBV) and human papilloma virus (HPV), bacteria, e.g., Mycoplasma hyorhinis and Salmonella Typhi, the protozoan parasite Toxoplasma gondii, the fungus Aspergillus flavus, and liver flukes such as Clonorchissinensis or Opisthorchis viverrini, may induce malignant transformation in hepatocytes or in target cells of the biliary tract through aberrant Wnt signaling activation. This review focuses on new insights into infectious agents implicated in the deregulation of Wnt signaling and PLC development. Since the Wnt/β-catenin pathway is a driver of cancer following viral and bacterial infections, molecules inhibiting the complex axis of Wnt signaling could represent novel therapeutic approaches in PLC treatment.

Research Progress of Fecal Microbiota Transplantation in Liver Diseases

A growing body of evidence suggested that gut microbiota is associated with liver diseases through the gut-liver axis. The imbalance of gut microbiota could be correlated with the occurrence, development, and prognosis of a series of liver diseases, including alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), viral hepatitis, cirrhosis, primary sclerosing cholangitis (PSC), and hepatocellular carcinoma (HCC). Fecal microbiota transplantation (FMT) seems to be a method to normalize the patient's gut microbiota. This method has been traced back to the 4th century. In recent decade, FMT has been highly regarded in several clinical trials. As a novel approach to reconstruct the intestinal microecological balance, FMT has been used to treat the chronic liver diseases. Therefore, in this review, the role of FMT in the treatment of liver diseases was summarized. In addition, the relationship between gut and liver was explored through the gut-liver axis, and the definition, objectives, advantages, and procedures of FMT were described. Finally, the clinical value of FMT therapy in liver transplant (LT) recipients was briefly discussed.

Dietary supplementation of bilberry anthocyanin on growth performance, intestinal mucosal barrier and cecal microbes of chickens challenged with Salmonella Typhimurium

BACKGROUND

Anthocyanins (AC) showed positive effects on improving the intestinal health and alleviating intestinal pathogen infections, therefore, an experiment was conducted to explore the protective effects of supplemented AC on Salmonella-infected chickens.

METHODS

A total of 240 hatchling chickens were randomly allocated to 4 treatments, each with 6 replicates. Birds were fed a basal diet supplemented with 0 (CON, and ST), 100 (ACL) and 400 (ACH) mg/kg of AC for d 60, and orally challenged with PBS (CON) or 10⁹ CFU/bird (ST, ACL, ACH) Salmonella Typhimurium at d 14 and 16.

RESULTS

(1) Compared with birds in ST, AC supplementation increased the body weight (BW) at d 18 and the average daily gain (ADG) from d 1 to 18 of the Salmonella-infected chickens (P < 0.05); (2) AC decreased the number of Salmonella cells in the liver and spleen, the contents of NO in plasma and inflammatory cytokines in ileal mucosa of Salmonella-infected chickens (P < 0.05); (3) Salmonella infection decreased the ileal villi height, villi height to crypt depth (V/C), and the expression of zonulaoccludins-1 (ZO-1), claudin-1, occludin, and mucin 2 (MUC2) in ileal mucosa. AC supplementation relieved these adverse effects, and decreased ileal crypt depth (P < 0.05); (4) In cecal microbiota of Salmonella-infected chickens, AC increased (P < 0.05) the alpha-diversity (Chao1, Pd, Shannon and Sobs indexes) and the relative abundance of Firmicutes, and decreased (P < 0.05) the relative abundance of Proteobacteria and Bacteroidota and the enrichment of drug antimicrobial resistance, infectious bacterial disease, and immune disease pathways.

CONCLUSIONS

Dietary AC protected chicken against Salmonella infection via inhibiting the Salmonella colonization in liver and spleen, suppressing secretion of inflammatory cytokines, up-regulating the expression of ileal barrier-related genes, and ameliorating the composition and function of cecal microbes. Under conditions here used, 100 mg/kg bilberry anthocyanin was recommended.

Extensive Summary of the Important Roles of Indole Propionic Acid, a Gut Microbial Metabolite in Host Health and Disease

Increasing evidence suggests that metabolites produced by the gut microbiota play a crucial role in host-microbe interactions. Dietary tryptophan ingested by the host enters the gut, where indole-like metabolites such as indole propionic acid (IPA) are produced under deamination by commensal bacteria. Here, we summarize the IPA-producing bacteria, dietary patterns on IPA content, and functional roles of IPA in various diseases. IPA can not only stimulate the expression of tight junction (TJ) proteins to enhance gut barrier function and inhibit the penetration of toxic factors, but also modulate the immune system to exert anti-inflammatory and antioxidant effects to synergistically regulate body physiology. Moreover, IPA can act on target organs through blood circulation to form the gut-organ axis, which helps maintain systemic homeostasis. IPA shows great potential for the diagnosis and treatment of various clinical diseases, such as NAFLD, Alzheimer's disease, and breast cancer. However, the therapeutic effect of IPA depends on dose, target organ, or time. In future studies, further work should be performed to explore the effects and mechanisms of IPA on host health and disease to further improve the existing treatment program.

Changes in antibiotic residues and the gut microbiota during ciprofloxacin administration throughout Silkie chicken development

The use of antibiotics leads to antibiotic residues in livestock and poultry products, adversely affecting human health. Ciprofloxacin (CFX) is a broad-spectrum antibiotic shared between animals and humans that is useful in treatments besides infections. However, changes in the gut microbiota caused by CFX and the possible link with the elimination of CFX residues have not been investigated. Herein, we used the Silkie chicken model to study the changes in the gut microbiota during the entire CFX-metabolic repertoire. We detected CFX residues in different tissues and showed that the elimination time of CFX from different tissues was dissimilar (liver > kidney > chest muscle > skin). Analysis of liver and kidney injury biomarkers and plasma antioxidant indices indicated slight hepatotoxicity and nephrotoxicity in the Silkie chickens. Importantly, the changes in the gut microbial community predominantly occurred early in the metabolic process. Correlation analysis revealed that the particular bacterial microbiota were associated with the pharmacokinetics of CFX in different Silkie chicken tissues (e.g., aerobic bacteria, including Escherichia and Coprococcus, and anaerobic bacteria, including Fusobacterium, Ruminococcus, Bifidobacterium, and Eubacterium). Collectively, certain microbiota may boost antibiotic metabolism and participate in restoring the microbial consortia after CFX is metabolized. Therefore, regulating the core intestinal microbiota may reduce foodborne antibiotics and accelerate the development of drug resistance.

Role of Intestinal Microbes in Chronic Liver Diseases

With the recent availability and upgrading of many emerging intestinal microbes sequencing technologies, our research on intestinal microbes is changing rapidly. A variety of investigations have found that intestinal microbes are essential for immune system regulation and energy metabolism homeostasis, which impacts many critical organs. The liver is the first organ to be traversed by the intestinal portal vein, and there is a strong bidirectional link between the liver and intestine. Many intestinal factors, such as intestinal microbes, bacterial composition, and intestinal bacterial metabolites, are deeply involved in liver homeostasis. Intestinal microbial dysbiosis and increased intestinal permeability are associated with the pathogenesis of many chronic liver diseases, such as alcoholic fatty liver disease (AFLD), non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), chronic hepatitis B (CHB), chronic hepatitis C (CHC), autoimmune liver disease (AIH) and the development of hepatocellular carcinoma (HCC). Intestinal permeability and dysbacteriosis often lead to Lipopolysaccharide (LPS) and metabolites entering in serum. Then, Toll-like receptors activation in the liver induces the exposure of the intestine and liver to many small molecules with pro-inflammatory properties. And all of these eventually result in various liver diseases. In this paper, we have discussed the current evidence on the role of various intestinal microbes in different chronic liver diseases. As well as potential new therapeutic approaches are proposed in this review, such as antibiotics, probiotics, and prebiotics, which may have an improvement in liver diseases.

Dysregulation of NK and CD8+T Cells by the Microbiota Promotes the Progression of Lung Cancer

The commensal microbiota is involved in maintaining local pulmonary immune homeostasis under physiological conditions. Alterations in the amount and dominant species of the microbiota can reshape the immune response of the body and lead to a variety of lung diseases, including cancer. The precise mechanisms by which microbiota regulate immune cells during the progression of lung cancer remain obscure. In this study, using a Kras-mutated-driven spontaneous lung cancer mouse model, we found that the depletion of microbiota can alleviate lung lesions in Kras-mutated mice at different stages of tumour development. Long-term antibiotic treatment significantly reduced the number NK cells and IFN-γ secretion and CD8⁺T cells in the lungs of wild-type (WT) mice, suggesting that the microbiota plays an important role in maintaining homeostasis of NK cells and CD8⁺T cells under normal conditions. However, in Kras-mutated mice, the altered pulmonary immune microenvironment resulted in a microbiota disorder and in the loss of the ability to regulate the immune responses of NK cells and CD8⁺T cells, thus promoting the occurrence and development of lung cancer. Further mechanistic studies have shown that the CXCL9-CXCR3 axis participated in the local recruitment of NK cells and CD8⁺T cells by the microbiota into lung tissues in Kras-mutated mice. Our findings reveal the role of the microbiota in reshaping tumour-related immune responses involving NK cells and CD8⁺T cells and shed light on the clinical immunotherapy of lung cancer.

Gut microbiota alteration and modulation in hepatitis B virus-related fibrosis and complications: Molecular mechanisms and therapeutic inventions

Hepatitis B virus (HBV) has posed a threat to public health, mainly resulting in liver damage. With long-term accumulation of extracellular matrix, patients with chronic hepatitis B are at high risk of developing into liver fibrosis and cirrhosis and even life-threatening hepatic carcinoma. The occurrence of complications such as spontaneous bacterial peritonitis and hepatic encephalopathy greatly increases disability and mortality. With deeper understanding of the bidirectional interaction between the liver and the gut (gut-liver axis), there is a growing consensus that the human health closely relates to the gut microbiota. Supported by animal and human studies, the gut microbiota alters as the HBV-related liver fibrosis initials and progresses, characterized as the decrease of the ratio between “good” and “potentially pathogenic” microbes. When the primary disease is controlled via antiviral treatment, the gut microbiota dysfunction tends to be improved. Conversely, the recovery of gut microbiota can promote the regression of liver fibrosis. Therapeutic strategies targeted on gut microbiota (rifaximin, probiotics, engineered probiotics and fecal microbiota transplantation) have been applied to animal models and patients, obtaining satisfactory results.

Potential Gut Microbiota Features for Non-Invasive Detection of Schistosomiasis

The gut microbiota has been identified as a predictive biomarker for various diseases. However, few studies focused on the diagnostic accuracy of gut microbiota derived-signature for predicting hepatic injuries in schistosomiasis. Here, we characterized the gut microbiomes from 94 human and mouse stool samples using 16S rRNA gene sequencing. The diversity and composition of gut microbiomes in Schistosoma japonicum infection-induced disease changed significantly. Gut microbes, such as Bacteroides, Blautia, Enterococcus, Alloprevotella, Parabacteroides and Mucispirillum, showed a significant correlation with the level of hepatic granuloma, fibrosis, hydroxyproline, ALT or AST in S. japonicum infection-induced disease. We identified a range of gut bacterial features to distinguish schistosomiasis from hepatic injuries using the random forest classifier model, LEfSe and STAMP analysis. Significant features Bacteroides, Blautia, and Enterococcus and their combinations have a robust predictive accuracy (AUC: from 0.8182 to 0.9639) for detecting liver injuries induced by S. japonicum infection in humans and mice. Our study revealed associations between gut microbiota features and physiopathology and serological shifts of schistosomiasis and provided preliminary evidence for novel gut microbiota-derived features for the non-invasive detection of schistosomiasis.

Faecal Microbiota Transplantation and Chronic Kidney Disease

Faecal microbiota transplantation (FMT) has attracted increasing attention as an intervention in many clinical conditions, including autoimmune, enteroendocrine, gastroenterological, and neurological diseases. For years, FMT has been an effective second-line treatment for Clostridium difficile infection (CDI) with beneficial outcomes. FMT is also promising in improving bowel diseases, such as ulcerative colitis (UC). Pre-clinical and clinical studies suggest that this microbiota-based intervention may influence the development and progression of chronic kidney disease (CKD) via modifying a dysregulated gut–kidney axis. Despite the high morbidity and mortality due to CKD, there are limited options for treatment until end-stage kidney disease occurs, which results in death, dialysis, or kidney transplantation. This imposes a significant financial and health burden on the individual, their families and careers, and the health system. Recent studies have suggested that strategies to reverse gut dysbiosis using FMT are a promising therapy in CKD. This review summarises the preclinical and clinical evidence and postulates the potential therapeutic effect of FMT in the management of CKD.

Baicalin Alleviates Short-Term Lincomycin-Induced Intestinal and Liver Injury and Inflammation in Infant Mice

The adverse effects of short-term megadose of antibiotics exposure on the gastrointestinal and liver tissue reactions in young children have been reported. Antibiotic-induced intestinal and liver reactions are usually unpredictable and present a poorly understood pathogenesis. It is, therefore, necessary to develop strategies for reducing the adverse effects of antibiotics. Studies on the harm and rescue measures of antibiotics from the perspective of the gut–liver system are lacking. Here, we demonstrate that lincomycin exposure reduced body weight, disrupted the composition of gut microbiota and intestinal morphology, triggered immune-mediated injury and inflammation, caused liver dysfunction, and affected lipid metabolism. However, baicalin administration attenuated the lincomycin-induced changes. Transcriptome analysis showed that baicalin improved immunity in mice, as evidenced by the decreased levels of intestinal inflammatory cytokines and expression of genes that regulate Th1, Th2, and Th17 cell differentiation, and inhibited mucin type O-glycan biosynthesis pathways. In addition, baicalin improved liver function by upregulating the expression of genes involved in bile acid secretion and lipid degradation, and downregulating genes involved in lipid synthesis in lincomycin-treated mice. Bile acids can regulate intestinal immunity and strengthen hepatoenteric circulation. In addition, baicalin also improved anti-inflammatory bacteria abundance (Blautia and Coprobacillus) and reduced pathogenic bacteria abundance (Proteobacteria, Klebsiella, and Citrobacter) in lincomycin-treated mice. Thus, baicalin can ameliorate antibiotic-induced injury and its associated complications such as liver disease.

Fecal Microbiota Transplantation Alters the Outcome of Hepatitis B Virus Infection in Mice

The susceptibility of mice to hepatitis B virus (HBV) infection depends on their genetic background. The gut microbiota modulates the antiviral immune response in the liver and plays a protective role against HBV infection. However, whether HBV infection outcomes depend on the gut microbiota remains unclear. In this study, we assessed the gut microbiota composition in naïve BALB/c and C57BL/6 mice using 16S rRNA gene sequencing. The gut microbiota in BALB/c mice was depleted using broad-spectrum antibiotics (ABX) and then reconstituted with fecal microbiota from naïve BALB/c or C57BL/6 mice to evaluate the effect of fecal microbiota transplantation (FMT) on the outcomes of and immune response to HBV infection. We found that HBV infection outcomes and the gut microbiota composition differed between BALB/c and C57BL/6 mice. Commensal bacteria from the fecal microbiota selectively colonized the guts of ABX-treated BALB/c mice. Mice receiving fecal microbiota from BALB/c or C57BL/6 mice displayed different HBV infection outcomes. The fecal microbiota from C57BL/6 mice induced immune tolerance in the liver and prolonged HBV infection. In conclusion, HBV infection outcomes in mice are determined by the host genetic background and gut microbiota composition. Reconstitution of the gut microbiota by FMT can alter the susceptibility to HBV infection in mice.

The Apparent Asymmetrical Relationship Between Small Bowel Bacterial Overgrowth, Endotoxemia, and Liver Steatosis and Fibrosis in Cirrhotic and Non-Cirrhotic Patients: A Single-Center Pilot Study

Introduction

Gut microbiota are a complex ecosystem harboring our intestine. They maintain human body equilibrium, while their derangement, namely, “dysbiosis“, has been associated with several gastrointestinal diseases, such as liver steatosis (NAFLD) and liver cirrhosis. Small intestinal bacterial overgrowth (SIBO) is an example of dysbiosis of the upper gastrointestinal (GI) tract.

Aim

The aim of this study is to evaluate the relationship between SIBO and levels of endotoxemia and grade of liver steatosis (LS) and liver fibrosis (LF) in hepatologic patients.

Materials and Methods

Consecutive outpatients referred to our hepatology clinic were tested for SIBO by the lactulose breath test (LBT) and peripheral blood levels of endotoxemia; LS grading and LF were assessed by abdominal ultrasound and transient elastography, respectively.

Results

Fifty-two consecutive patients (17 with alcohol abuse (4.5 ± 0.8 alcohol units per day), 4 with HCV and 2 with HBV infection, 24 of metabolic origin, 2 of autoimmune origin, and 3 with cholangiopathies; mean age 54.7 ± 8.3 years, 31 F, BMI 24.1 ± 1.1 Kg/m²) and 14 healthy volunteers (HV) (mean age 50.1 ± 4.3 years, 9 F, BMI 23.3 ± 1.1 Kg/m²) were enrolled. SIBO prevalence was significantly higher in cirrhotic (LC) vs. non-cirrhotic (LNC) patients and vs. HV (all, p < 0.05), with a significant positive trend according to Child-Pugh status (all, p < 0.05). SIBO prevalence was not correlated with LS stages (all, p = NS). Consensually, endotoxin levels were significantly higher in LC vs. LNC and vs. HV (all, p < 0.05) and significantly correlated with LF in patients with LC, according to Child-Pugh status (all, p < 0.05).

Conclusion

This study shows that SIBO prevalence and relative endotoxin blood levels seem to be significantly associated with the grade of LF vs. LS in LC. SIBO is also present under pre-cirrhotic conditions, but its prevalence seems to correlate with liver disease irreversible derangement.

Gut Microbiota Dysbiosis Strengthens Kupffer Cell-mediated Hepatitis B Virus Persistence through Inducing Endotoxemia in Mice

BACKGROUND AND AIMS

Change of gut microbiota composition is associated with the outcome of hepatitis B virus (HBV) infection, yet the related mechanisms are not fully characterized. The objective of this study was to investigate the immune mechanism associated with HBV persistence induced by gut microbiota dysbiosis.

METHODS

C57BL/6 mice were sterilized for gut-microbiota by using an antibiotic (ABX) mixture protocol, and were monitored for their serum endotoxin (lipopolysaccharide [LPS]) levels. An HBV-replicating mouse model was established by performing HBV-expressing plasmid pAAV/HBV1.2 hydrodynamic injection (HDI) with or without LPS, and was monitored for serum hepatitis B surface antigen, hepatitis B e antigen, HBV DNA, and cytokine levels. Kupffer cells (KCs) were purified from antibiotic-treated mice and HBV-replicating mice and analyzed for IL-10 production and T cell suppression ability.

RESULTS

ABX treatment resulted in increased serum LPS levels in mice. The KCs separated from both ABX-treated and LPS-treated HBV-replicating mice showed significantly increased IL-10 production and enhanced ability to suppress IFN-γ production of TCR-activated T cells than the KCs separated from their counterpart controls. HDI of pAAV/HBV1.2 in combination with LPS in mice led to a delayed HBV clearance and early elevation of serum IL-10 levels compared to pAAV/HBV1.2 HDI alone. Moreover, IL-10 function blockade or KC depletion led to accelerated HBV clearance in LPS-treated HBV-replicating mice.

CONCLUSIONS

Our results suggest that dysbiosis of the gut microbiota in mice leads to endotoxemia, which induces KC IL-10 production and strengthens KC-mediated T cell suppression, and thus facilitates HBV persistence.

Oral Administration of Water Extract from Euglena gracilis Alters the Intestinal Microbiota and Prevents Lung Carcinoma Growth in Mice

The antitumor effects of a partially purified water extract from Euglena gracilis (EWE) and EWE treated by boiling (bEWE) were evaluated using orthotopic lung cancer syngeneic mouse models with Lewis lung carcinoma (LLC) cells. Daily oral administration of either EWE or bEWE started three weeks prior to the inoculation of LLC cells significantly attenuated tumor growth as compared to the phosphate buffered saline (PBS) control, and the attenuation was further enhanced by bEWE. The intestinal microbiota compositions in both extract-treated groups were more diverse than that in the PBS group. Particularly, a decrease in the ratio of Firmicutes to Bacteroidetes and significant increases in Akkermansia and Muribaculum were observed in two types of EWE-treated groups. Fecal microbiota transplantation (FMT) using bEWE-treated mouse feces attenuated tumor growth to an extent equivalent to bEWE treatment, while tumor growth attenuation by bEWE was abolished by treatment with an antibiotic cocktail. These studies strongly suggest that daily oral administration of partially purified water extracts from Euglena gracilis attenuates lung carcinoma growth via the alteration of the intestinal microbiota.

Bile Acid Regulates the Colonization and Dissemination of Candida albicans from the Gastrointestinal Tract by Controlling Host Defense System and Microbiota

Candida albicans (CA), a commensal and opportunistic eukaryotic organism, frequently inhabits the gastrointestinal (GI) tract and causes life-threatening infections. Antibiotic-induced gut dysbiosis is a major risk factor for increased CA colonization and dissemination from the GI tract. We identified a significant increase of taurocholic acid (TCA), a major bile acid in antibiotic-treated mice susceptible to CA infection. In vivo findings indicate that administration of TCA through drinking water is sufficient to induce colonization and dissemination of CA in wild-type and immunosuppressed mice. Treatment with TCA significantly reduced mRNA expression of immune genes ang4 and Cxcr3 in the colon. In addition, TCA significantly decreased the relative abundance of three culturable species of commensal bacteria, Turicibacter sanguinis, Lactobacillus johnsonii, and Clostridium celatum, in both cecal contents and mucosal scrapings from the colon. Taken together, our results indicate that TCA promotes fungal colonization and dissemination of CA from the GI tract by controlling the host defense system and intestinal microbiota that play a critical role in regulating CA in the intestine.