Ampicillin exacerbates acetaminophen-induced acute liver injury by inducing intestinal microbiota imbalance and butyrate reduction

Toxic effects of avermectin on liver function, gut microbiota, and colon barrier in the rat model

Avermectin (AVM), a compound derived from the fermentation of Avermectin Streptomyces, has insecticidal, acaricidal, and nematicidal properties. Widely employed in agriculture, it serves as an effective and broad-spectrum insecticide for pest control. Although the toxicity of AVM at low doses may not be readily apparent, prolonged and extensive exposure can result in poisoning. To investigate the toxic effects of AVM on the body, this study established rat models of AVM poisoning with both low and high concentrations of the compound. Fifteen male rats were randomly assigned to one of three groups (n=5 per group): a control group, a low-concentration group, and a high-concentration group. The low-concentration group was administered an oral dose of 2 mg/kg AVM once daily for a duration of seven days, while the high-concentration group received an oral dose of 10 mg/kg AVM once daily for the same period. This study examined the impact of AVM on liver function and gut microbiota in rats using weight monitoring, liver function indicator detection, liver metabolomics sequencing, colon barrier function testing, and gut microbiota sequencing. The findings of this study demonstrated that exposure to 2 or 10 mg/kg AVM for seven days can lead to a notable decrease in rat weight, as well as induce liver dysfunction and metabolic disturbances. Additionally, AVM exposure can disrupt the composition of the intestinal microbiota and impair the integrity of the colon mucosal barrier, causing downregulation of Occludin expression and upregulation of inflammation-related protein expression levels such as IL-1β, Myd88, and TLR4. Furthermore, bioinformatics analysis revealed a significant association between liver dysfunction and dysbiosis of the gut microbiota. These findings have implications for the agricultural use of AVM and its potential contribution to environmental pollution. Consequently, individuals involved in AVM usage should prioritize safety precautions and monitor liver function.

The Discovery of Gut Microbial Metabolites as Modulators of Host Susceptibility to Acetaminophen-Induced Hepatotoxicity

The mammalian gut microbiota plays diverse and essential roles in modulating host physiology. Key mediators determining the outcome of the microbiota-host interactions are the small molecule metabolites produced by the gut microbiota. The liver is a major organ exposed to gut microbial metabolites, and it serves as the nexus for maintaining healthy interactions between the gut microbiota and the host. At the same time, the liver is the primary target of potentially harmful gut microbial metabolites. In this review, we provide an up-to-date list of gut microbial metabolites that have been identified to either increase or decrease host susceptibility to acetaminophen (APAP)-induced liver injury. The signaling pathways and molecular factors involved in the progression of APAP-induced hepatotoxicity are well-established, and we propose that the mouse model of APAP-induced hepatotoxicity serves as a model system for uncovering gut microbial metabolites with previously unknown functions. Furthermore, we envision that gut microbial metabolites identified to alter APAP-induced hepatotoxicity likely have broader implications in other liver diseases. SIGNIFICANCE STATEMENT: This review provides an overview of the role of the gut microbiota in modulating the host susceptibility to acetaminophen (APAP)-induced liver injury. It focuses on the roles of gut bacterial small molecule metabolites as mediators of the interaction between the gut microbiota and the liver. It also illustrates the utility of APAP-induced liver injury as a model to identify gut microbial metabolites with biological function.

Role of Gut Microecology in the Pathogenesis of Drug-Induced Liver Injury and Emerging Therapeutic Strategies

Drug-induced liver injury (DILI) is a common clinical pharmacogenic disease. In the United States and Europe, DILI is the most common cause of acute liver failure. Drugs can cause hepatic damage either directly through inherent hepatotoxic properties or indirectly by inducing oxidative stress, immune responses, and inflammatory processes. These pathways can culminate in hepatocyte necrosis. The role of the gut microecology in human health and diseases is well recognized. Recent studies have revealed that the imbalance in the gut microecology is closely related to the occurrence and development of DILI. The gut microecology plays an important role in liver injury caused by different drugs. Recent research has revealed significant changes in the composition, relative abundance, and distribution of gut microbiota in both patients and animal models with DILI. Imbalance in the gut microecology causes intestinal barrier destruction and microorganism translocation; the alteration in microbial metabolites may initiate or aggravate DILI, and regulation and control of intestinal microbiota can effectively mitigate drug-induced liver injury. In this paper, we provide an overview on the present knowledge of the mechanisms by which DILI occurs, the common drugs that cause DILI, the gut microbiota and gut barrier composition, and the effects of the gut microbiota and gut barrier on DILI, emphasizing the contribution of the gut microecology to DILI.

Mesenchymal stem cell-derived exosomes promote tissue repair injury in rats with liver trauma by regulating gut microbiota and metabolism

OBJECTIVE

The effects of mesenchymal stem cells (MSCs) and MSC-derived exosomes (MSC-exos) on serum metabolites and intestinal microbiota in rats after liver trauma were discussed.

METHODS

Adult Wistar Albino rats were assigned into control, model (liver trauma), MSCs, and MSC-exos groups (n = 6). The study examined changes in the inflammatory environment in liver tissues were analyzed by histological examination and analysis of macrophage phenotypes. Alterations in serum metabolites were determined by untargeted metabonomics, and gut microbiota composition was characterized by 16S rDNA sequencing. Correlations between specific gut microbiota, metabolites, and inflammatory response were calculated using Spearman correlation analysis.

RESULTS

Rats with liver trauma after MSCs and MSC-exos treatment exhibited attenuated inflammatory infiltration and necrosis in liver tissues. MSCs and MSC-exos treatment reduced the proportion of M1 macrophages, accompanied by a decrease in inducible nitric oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-α) levels. Furthermore, MSCs and MSC-exos treatment expanded the proportion of M2 macrophages, accompanied by an increase in arginase-1 (Arg-1) and interleukin-10 (IL-10) levels. The beneficial effects of MSC-exo treatment on rats with liver trauma were superior to those of MSC treatment. The composition and abundance of the gut microbiota and metabolites were altered in pathological rats, whereas MSC and MSC-exo intervention partially restored specific gut microbiota and metabolite alterations. At the phylum level, alterations in Bacteroidota, Proteobacteria, and Verrucomicrobiota were observed after MSC and MSC-exo intervention. At the genus level, Intestinimonas, Alistipes, Aerococcus, Faecalibaculum, and Lachnospiraceae_ND3007_group were the main differential microbiota. 6-Methylnicotinamide, N-Methylnicotinamide, Glutathione, oxidized, ISOBUTYRATE, ASCORBATE, EICOSAPENTAENOATE, GLYCEROL 3-PHOSPHATE, and Ascorbate radical were selected as important differential metabolites. There was a clear correlation between Ascorbate, Intestinimonas/Faecalibaculum and inflammatory cytokines.

CONCLUSION

MSC-exos promoted the repair of tissue damage in rats with liver trauma by regulating serum metabolites and intestinal microbiota, providing new insights into how MSC-exos reduced inflammation in rats with liver trauma.

Gut-Liver Axis as a Therapeutic Target for Drug-Induced Liver Injury

Drug-induced liver injury (DILI) is a liver disease that remains difficult to predict and diagnose, and the underlying mechanisms are yet to be fully clarified. The gut-liver axis refers to the reciprocal interactions between the gut and the liver, and its homeostasis plays a prominent role in maintaining liver health. It has been recently reported that patients and animals with DILI have a disrupted gut-liver axis, involving altered gut microbiota composition, increased intestinal permeability and lipopolysaccharide translocation, decreased short-chain fatty acids production, and impaired bile acid metabolism homeostasis. The present review will summarize the evidence from both clinical and preclinical studies about the role of the gut-liver axis in the pathogenesis of DILI. Moreover, we will focus attention on the potential therapeutic strategies for DILI based on improving gut-liver axis function, including herbs and phytochemicals, probiotics, fecal microbial transplantation, postbiotics, bile acids, and Farnesoid X receptor agonists.

Wolfberry, Yam, and Chrysanthemum polysaccharides increased intestinal Akkermansia muciniphila abundance and hepatic YAP1 expression to alleviate DILI

Drug-induced liver injury (DILI) is frequently induced by high dose of acetaminophen (APAP) and is concomitant with disturbances of gut flora. Akkermansia muciniphila is beneficial for the repair of liver injury. Lycium barbarum polysaccharide, yam polysaccharide, and chrysanthemum polysaccharide all have anti-inflammatory and antioxidation effects. The objective of this study is to investigate the potential of lycium barbarum polysaccharide, yam polysaccharide, and chrysanthemum polysaccharide (LYC) in improving DILI by increasing the abundance of A. muciniphila. Initially, screening for the optimal concentrations of wolfberry, yam, and chrysanthemum (WYC) or LYC to promote A. muciniphila proliferation in vitro and validated in antibiotic (ATB)-treated KM mice. Subsequently, APAP-induced DILI model in BALB/c mice were constructed to examine the treatment effects of LYC. Our findings indicate that the optimal concentration ratio of WYC was 2:3:2, and LYC was 1:1:1. WYC increased A. muciniphila proliferation in vitro and in ATB-treated mice under this ratio. Meanwhile, LYC increased A. muciniphila abundance in vitro and the combination LYC with A. muciniphila promoted the proliferation of A. muciniphila in ATB-treated mice. The overdose of APAP resulted in the impairment of the intestinal barrier function and subsequent leakage of lipopolysaccharide (LPS). Moreover, LYC increased A. muciniphila abundance, reduced intestinal inflammation and permeability, and upregulated the expression of the tight junction protein zonula occludens protein 1 (ZO-1) and occludin contents in the gut. Lastly, LYC inhibited LPS leakage and upregulated hepatic YAP1 expression, ultimately leading to the repair of DILI.

Host ALDH2 deficiency aggravates nonalcoholic steatohepatitis through gut-liver axis

Nonalcoholic steatohepatitis (NASH) is the major cause of liver dysfunction. Animal and population studies have shown that mitochondrial aldehyde dehydrogenase (ALDH2) is implicated in fatty liver disease. However, the role of ALDH2 in NASH and the underlying mechanisms remains unclear. To address this issue, ALDH2 knockout (ALDH2-/-) mice and wild-type littermate mice were fed a methionine-and choline-deficient (MCD) diet to induce a NASH model. Fecal, serum, and liver samples were collected and analyzed to investigate the impact of the gut microbiota and bile acids on this process. We found that MCD-fed ALDH2-/- mice exhibited increased serum pro-inflammation cytokines, hepatic inflammation and fat accumulation than their wild-type littermates. MCD-fed ALDH2-/- mice exhibited worsened MCD-induced intestinal inflammation and barrier damage, and gut microbiota disorder. Furthermore, mice receiving microbiota from MCD-fed ALDH2-/- mice had increased severity of NASH compared to those receiving microbiota from MCD-fed wild-type mice. Notably, the intestinal Lactobacillus was significantly reduced in MCD-fed ALDH2-/- mice, and gavage with Lactobacillus cocktail significantly improved MCD-induced NASH. Finally, we found that ALDH2-/- mice had reduced levels of bile salt hydrolase and specific bile acids, especially lithocholic acid (LCA), accompanied by downregulated expression of the intestinal FXR-FGF15 pathway. Supplementation of LCA in ALDH2-/- mice upregulated intestinal FXR-FGF15 pathway and alleviated NASH. In summary, ALDH2 plays a critical role in the development of NASH through modulation of gut microbiota and bile acid. The findings suggest that supplementing with Lactobacillus or LCA could be a promising therapeutic approach for treating NASH exacerbated by ALDH2 deficiency.

Contribution of gut microbiota to drug-induced liver injury

Drug-induced liver injury (DILI) is caused by various drugs with complex pathogenesis, and diverse clinical and pathological phenotypes. Drugs damage the liver directly through drug hepatotoxicity, or indirectly through drug-mediated oxidative stress, immune injury and inflammatory insult, which eventually lead to hepatocyte necrosis. Recent studies have found that the composition, relative content and distribution of gut microbiota in patients and animal models of DILI have changed significantly. It has been confirmed that gut microbial dysbiosis brings about intestinal barrier destruction and microorganisms translocation, and the alteration of microbial metabolites may cause or aggravate DILI. In addition, antibiotics, probiotics, and fecal microbiota transplantation are all emerging as prospective therapeutic methods for DILI by regulating the gut microbiota. In this review, we discussed how the altered gut microbiota participates in DILI.

Fecal microbiome transplant from patients with lactation mastitis promotes mastitis in conventional lactating mice

Introduction

Lactation mastitis seriously severely affects the health of lactating females and their infants, yet the underlying causes of clinical lactation mastitis remain unclear.

Methods

In this study, we used microbiota-humanized mice as a model to investigate the role of gut microbiota in lactation mastitis. We compared the fecal microbiota of lactation mastitis patients and healthy individuals and conducted fecal microbiota transplantation (FMT) experiments in an antibiotic-pretreated mouse model to test whether gut microbes contribute to human lactation mastitis.

Results

Our results showed that gut microbiota diversity was reduced and dysbiosis was present in lactating mastitis patients. FMT from lactation mastitis patients (M-FMT), but not from healthy individuals (H-FMT), to antibiotic-treated mice resulted in lactation mastitis. The inflammation in mice caused by gut microbiota from lactating mastitis patients appears to be pervasive, as hepatocytes from mice that received feces from lactating mastitis patients showed marked swelling. In addition, serum pro-inflammatory factors, including IL-4, IL-17, MPO, IL-6, IL-1β, and TNF-α, were significantly increased in the M-FMT group. The Firmicutes/Bacteroidetes ratio (F/B), a biomarker of gut dysbiosis, was significantly increased in the M-FMT group. At the phylum level, Actinobacteria were significantly increased, and Verrucomicrobia were significantly decreased in the M-FMT group. At the genus level, Ruminococcus and Faecalibacterium were significantly reduced, while Parabacteroides were significantly increased in the feces of both patients with lactation mastitis and M-FMT mice. Moreover, our study revealed an "amplification effect" on microbiota differences and mastitis disease following human-to-mouse FMT.

Conclusion

Collectively, our findings demonstrate that the gut microbiota in lactating mastitis patients is dysbiotic and contributes to the pathogenesis of mastitis.