Microbiome dysbiosis and alcoholic liver disease☆

The pyruvate dehydrogenase kinase inhibitor dichloroacetate mitigates alcohol-induced hepatic inflammation and metabolic disturbances in mice

BACKGROUND

Dichloroacetate (DCA), a pan-pyruvate dehydrogenase kinase inhibitor, ameliorates multiple pathological conditions and tissue injury and shows strong potential for clinical applications. Here, we investigated the preventive effects of DCA in a murine model of alcohol-associated liver disease.

METHODS

C57BL/6J mice were subjected to the acute-on-chronic model of alcohol-associated liver disease and treated with DCA. Livers were assessed in liver histology, biochemistry, and gene expression. Mass spectrometry was used to compare protein expression and metabolite levels.

RESULTS

DCA inhibited hepatic expression of inflammatory genes but did not prevent steatosis and hepatocellular injury in ethanol-fed mice. Consistently, DCA repressed the expression of mRNAs for inflammatory genes in LPS-stimulated murine bone-marrow-derived macrophages and human monocytic THP-1 cells and inhibited both gene expression and protein release of interleukin-1 beta. DCA prevented hepatic accumulation of isovaleric acid in ethanol-fed mice, a short-chain fatty acid primarily produced by gut microbiota. In vitro, isovaleric acid potentiated LPS's effects, while DCA prevented this proinflammatory action. Ethanol feeding increased the expression of proteins involved in diverse metabolic pathways, including branched-chain amino acid (BCAA) degradation. In ethanol-fed mice, hepatic Fischer's ratio (the molar ratio of BCAAs to aromatic amino acids Phe and Tyr) and BTR (the molar ratio of BCAAs to Tyr) showed a decrease compared to pair-fed mice; however, this decrease was not observed in DCA-treated ethanol-fed mice. DCA blunted the ethanol-induced increase of BCKDHA, the rate-limiting enzyme in BCAA catabolism, and cytochrome P450 2E1.

CONCLUSIONS

Ethanol-induced hepatic inflammatory responses and metabolic disturbances were prevented by DCA in mice, indicating the potential to develop pyruvate dehydrogenase kinase inhibitors as an effective therapy to treat alcohol-associated liver disease.

Metagenomics Reveals Sex-Based Differences in Murine Fecal Microbiota Profiles Induced by Chronic Alcohol Consumption

Chronic ethanol exposure induces an inflammatory response within the intestinal tract, compromising mucosal and epithelial integrity and leading to dysbiosis of the gut microbiome. However, the specific roles of the gut microbiota in mediating ethanol-induced effects, as well as their interactions with the immune system, remain poorly characterized. This study aimed to evaluate sex-based differences in fecal microbiota profiles induced by chronic alcohol consumption and to assess whether TLR4 is involved in these effects. We analyzed the 16S rRNA gene sequencing of fecal samples from male and female wild-type (WT) and TLR4-knockout (TLR4-KO) mice with and without chronic ethanol exposure over a three-month period. Our findings provide evidence, for the first time, that male mice are more susceptible to the effects of ethanol on the fecal microbiota, since ethanol exposure induced greater alterations in the Gram-negative and -positive bacteria with immunogenic capacity in the WT male mice than in the female mice. We also demonstrate that the absence of immune receptor TLR4 leads to different microbiota in both sexes, showing anti-inflammatory and protective properties for intestinal barrier function and resulting in a phenotype more resistant to ethanol's effects. These findings may open new avenues for understanding the relationship between gut microbiota profiles and inflammation in the digestive system induced by chronic alcohol consumption.

The role of gut microbiome and its metabolites in pancreatitis

Gut microbiome plays a vital role in the intestinal ecosystem and has close association with metabolites. Due to the development of metabolomics and microbiomics, recent studies have observed that alteration of either the gut microbiome or metabolites may have effects on the progression of pancreatitis. Several new treatments based on the gut microbiome or metabolites have been studied extensively in recent years. Gut microbes, such as Bifidobacterium, Akkermansia, and Lactobacillus, and metabolites, such as short-chain fatty acids, bile acids, vitamin, hydrogen sulfide, and alcohol, have different effects on pancreatitis. Some preliminary studies about new intervention measures were based on the gut microbiome and metabolites such as diet, prebiotic, herbal medicine, and fecal microbiota transplantation. This review aims to summarize the recent advances about the gut microbiome, metabolites, and pancreatitis in order to determine the potential beneficial role of the gut microbiome and metabolites in pancreatitis.

The Modulatory Effects and Therapeutic Potential of Cannabidiol in the Gut

Cannabidiol (CBD) is a major non-psychotropic phytocannabinoid that exists in the Cannabis sativa plant. CBD has been found to act on various receptors, including both cannabinoid and non-cannabinoid receptors. In addition, CBD has antioxidant effects that are independent of receptors. CBD has demonstrated modulatory effects at different organ systems, such as the central nervous system, immune system, and the gastrointestinal system. Due to its broad effects within the body and its safety profile, CBD has become a topic of therapeutic interest. This literature review summarizes previous research findings with regard to the effect of CBD on the gastrointestinal (GI) system, including its effects at the molecular, cellular, organ, and whole-body levels. Both pre-clinical animal studies and human clinical trials are reviewed. The results of the studies included in this literature review suggest that CBD has significant impact on intestinal permeability, the microbiome, immune cells and cytokines. As a result, CBD has been shown to have therapeutic potential for GI disorders such as inflammatory bowel disease (IBD). Furthermore, through interactions with the gut, CBD may also be helpful in the treatment of disorders outside the GI system, such as non-alcoholic liver disease, postmenopausal disorders, epilepsy, and multiple sclerosis. In the future, more mechanistic studies are warranted to elucidate the detailed mechanisms of action of CBD in the gut. In addition, more well-designed clinical trials are needed to explore the full therapeutic potential of CBD on and through the gut.

Investigating the Impacts of Diet, Supplementation, Microbiota, Gut-Brain Axis on Schizophrenia: A Narrative Review

Schizophrenia is a disease with a complex etiology that significantly impairs the functioning of patients. In recent years, there has been increasing focus on the importance of the gut microbiota in the context of the gut-brain axis. In our study, we analyzed data on the gut-brain axis in relation to schizophrenia, as well as the impacts of eating habits, the use of various supplements, and diets on schizophrenia. Additionally, the study investigated the impact of antipsychotics on the development of metabolic disorders, such as diabetes, dyslipidemia, and obesity. There may be significant clinical benefits to be gained from therapies supported by supplements such as omega-3 fatty acids, B vitamins, and probiotics. The results suggest the need for a holistic approach to the treatment of schizophrenia, incorporating both drug therapy and dietary interventions.

Characteristics of microbiome-derived metabolomics according to the progression of alcoholic liver disease

BACKGROUND AND AIM

The prevalence and severity of alcoholic liver disease (ALD) are increasing. The incidence of alcohol-related cirrhosis has risen up to 2.5%. This study aimed to identify novel metabolite mechanisms involved in the development of ALD in patients. The use of gut microbiome-derived metabolites is increasing in targeted therapies. Identifying metabolic compounds is challenging due to the complex patterns that have long-term effects on ALD. We investigated the specific metabolite signatures in ALD patients.

METHODS

This study included 247 patients (heathy control, HC: n = 62, alcoholic fatty liver, AFL; n = 25, alcoholic hepatitis, AH; n = 80, and alcoholic cirrhosis, AC, n = 80) identified, and stool samples were collected. 16S rRNA sequencing and metabolomics were performed with MiSeq sequencer and liquid chromatography coupled to time-of-flight-mass spectrometry (LC-TOF-MS), respectively. The untargeted metabolites in AFL, AH, and AC samples were evaluated by multivariate statistical analysis and metabolic pathotypic expression. Metabolic network classifiers were used to predict the pathway expression of the AFL, AH, and AC stages.

RESULTS

The relative abundance of Proteobacteria was increased and the abundance of Bacteroides was decreased in ALD samples (p = 0.001) compared with that in HC samples. Fusobacteria levels were higher in AH samples (p = 0.0001) than in HC samples. Untargeted metabolomics was applied to quantitatively screen 103 metabolites from each stool sample. Indole-3-propionic acid levels are significantly lower in AH and AC (vs. HC, p = 0.001). Indole-3-lactic acid (ILA: p = 0.04) levels were increased in AC samples. AC group showed an increase in indole-3-lactic acid (vs. HC, p = 0.040) level. Compared with that in HC samples, the levels of short-chain fatty acids (SCFAs: acetic acid, butyric acid, propionic acid, iso-butyric acid, and iso-valeric acid) and bile acids (lithocholic acids) were significantly decreased in AC. The pathways of linoleic acid metabolism, indole compounds, histidine metabolism, fatty acid degradation, and glutamate metabolism were closely associated with ALD metabolism.

CONCLUSIONS

This study identified that microbial metabolic dysbiosis is associated with ALD-related metabolic dysfunction. The SCFAs, bile acids, and indole compounds were depleted during ALD progression.

CLINICAL TRIAL

Clinicaltrials.gov, number NCT04339725.

Mind over Microbes: Investigating the Interplay between Lifestyle Factors, Gut Microbiota, and Brain Health

BACKGROUND

The gut microbiota (GM) of the human body comprises several species of microorganisms. This microorganism plays a significant role in the physiological and pathophysiological processes of various human diseases.

METHODS

The literature review includes studies that describe causative factors that influence GM. The GM is sensitive to various factors like circadian rhythms, environmental agents, physical activity, nutrition, and hygiene that together impact the functioning and composition of the gut microbiome. This affects the health of the host, including the psycho-neural aspects, due to the interconnectivity between the brain and the gut. Hence, this paper examines the relationship of GM with neurodegenerative disorders in the context of these aforesaid factors.

CONCLUSION

Future studies that identify the regulatory pathways associated with gut microbes can provide a causal link between brain degeneration and the gut at a molecular level. Together, this review could be helpful in designing preventive and treatment strategies aimed at GM, so that neurodegenerative diseases can be treated.

Gut-derived ammonia contributes to alcohol-related fatty liver development via facilitating ethanol metabolism and provoking ATF4-dependent de novo lipogenesis activation

BACKGROUND & AIMS

Dysbiosis contributes to alcohol-associated liver disease (ALD); however, the precise mechanisms remain elusive. Given the critical role of the gut microbiota in ammonia production, we herein aim to investigate whether and how gut-derived ammonia contributes to ALD.

METHODS

Blood samples were collected from human subjects with/without alcohol drinking. Mice were exposed to the Lieber-DeCarli isocaloric control or ethanol-containing diets with and without rifaximin (a nonabsorbable antibiotic clinically used for lowering gut ammonia production) supplementation for five weeks. Both in vitro (NH4Cl exposure of AML12 hepatocytes) and in vivo (urease administration for 5 days in mice) hyperammonemia models were employed. RNA sequencing and fecal amplicon sequencing were performed. Ammonia and triglyceride concentrations were measured. The gene and protein expression of enzymes involved in multiple pathways were measured.

RESULTS

Chronic alcohol consumption causes hyperammonemia in both mice and human subjects. In healthy livers and hepatocytes, ammonia exposure upregulates the expression of urea cycle genes, elevates hepatic de novo lipogenesis (DNL), and increases fat accumulation. Intriguingly, ammonia promotes ethanol catabolism and acetyl-CoA formation, which, together with ammonia, synergistically facilitates intracellular fat accumulation in hepatocytes. Mechanistic investigations uncovered that ATF4 activation, as a result of ER stress induction and general control nonderepressible 2 activation, plays a central role in ammonia-provoked DNL elevation. Rifaximin ameliorates ALD pathologies in mice, concomitant with blunted hepatic ER stress induction, ATF4 activation, and DNL activation.

CONCLUSIONS

An overproduction of ammonia by gut microbiota, synergistically interacting with ethanol, is a significant contributor to ALD pathologies.

The role of faecal microbiota transplantation in chronic noncommunicable disorders

The gut microbiome plays a key role in influencing several pathways and functions involved in human health, including metabolism, protection against infection, and immune regulation. Perturbation of the gut microbiome is recognised as a pathogenic factor in several gastrointestinal and extraintestinal disorders, and is increasingly considered as a therapeutic target in these conditions. Faecal microbiota transplantation (FMT) is the transfer of the microbiota from healthy screened stool donors into the gut of affected patients, and is a well-established and highly effective treatment for recurrent Clostridioides difficile infection. Despite the mechanisms of efficacy of FMT not being fully understood, it has been investigated in several chronic noncommunicable disorders, with variable results. This review aims to give an overview of mechanisms of efficacy of FMT in chronic noncommunicable disorders, and to paint the current landscape of its investigation in these medical conditions, including inflammatory bowel disease (IBD), chronic liver disorders, and also extraintestinal autoimmune conditions.

New insight into gut microbiota-derived metabolites to enhance liver regeneration via network pharmacology study

We intended to identify favourable metabolite(s) and pharmacological mechanism(s) of gut microbiota (GM) for liver regeneration (LR) through network pharmacology. We utilized the gutMGene database to obtain metabolites of GM, and targets associated with metabolites as well as LR-related targets were identified using public databases. Furthermore, we performed a molecular docking assay on the active metabolite(s) and target(s) to verify the network pharmacological concept. We mined a total of 208 metabolites in the gutMGene database and selected 668 targets from the SEA (1,256 targets) and STP (947 targets) databases. Finally, 13 targets were identified between 61 targets and the gutMGene database (243 targets). Protein-protein interaction network analysis showed that AKT1 is a hub target correlated with 12 additional targets. In this study, we describe the potential microbe from the microbiota (E. coli), chemokine signalling pathway, AKT1 and myricetin that accelerate LR, providing scientific evidence for further clinical trials.

Bifidobacterium longum subsp. longum BL21 ameliorates alcoholic liver disease in mice through enhancement of the hepatic antioxidant capacity and modulation of the gut microbiota

BACKGROUND

Alcoholic liver disease (ALD) is a chronic liver injury caused by excessive alcohol consumption, could be impacted by gut-liver axis dysfunction. The gut microbiota plays a crucial role in the development and progression of ALD. Given the role of gut-liver axis dysfunction in ALD, strategies targeting gut microbiota modulation have gained interest for therapeutic interventions. Bifidobacterium longum subsp. longum BL21 has shown promise in alleviating gut microbiota disturbances and metabolic regulation in high-fat diet-induced obesity and type 2 diabetes mellitus models. Thus, this study aimed to evaluate the therapeutic effect of BL21 on ALD mice and explore the potential mechanism by which the gut microbiota mediates the amelioration of ALD by BL21.

METHODS

A total of 30 mice were randomly assigned to three groups (n = 10 mice/group): a healthy control (CTL) group, an ALD group, and a BL21 group. Each group was fed a Lieber-DeCarli liquid diet with (ALD and BL21) or without alcohol (CTL). The intervention period lasted 6 weeks, after which the effects of BL21 intervention (intragastric administration of 1 billion CFU of BL21 daily) on serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, hepatic oxidative stress, serum inflammatory cytokine levels, and gut microbiota composition in ALD mice were investigated.

RESULTS

Dietary BL21 reduced the ethanol-induced abnormal elevation of serum AST and ALT levels in ALD mice (P < 0.001 for both). BL21 treatment significantly attenuated alcohol-induced hepatic oxidative stress by decreasing malondialdehyde concentration and increasing superoxide dismutase, catalase, and glutathione concentrations in the livers of ALD mice. In addition, the serum levels of tumor necrosis factor-alpha, interleukin-1 beta (IL-1β), and IL-6 were significantly lower (P < 0.001 for both), while that of IL-10 was significantly higher (P < 0.05), in the BL21 group than in the ALD group. Intestinal microbiota analysis showed an increased relative abundance of Escherichia/Shigella, Enterococcus, and Alistipes in the ALD group compared with the CTL group. BL21 intervention increased the relative abundance of Bifidobacterium and Akkermansia compared with the ALD group.

CONCLUSION

Dietary BL21 ameliorates ALD via enhancement of the hepatic antioxidant capacity and modulation of the gut microbiota and may therefore be a promising strategy to prevent or treat ALD.

Oral Pathogenic Bacteria and the Oral-Gut-Liver Axis: A New Understanding of Chronic Liver Diseases

Liver diseases have long been a prevalent cause of morbidity and mortality, and their development and progression involve multiple vital organs throughout the body. Recent studies on the oral-gut-liver axis have revealed that the oral microbiota is associated with the pathophysiology of chronic liver diseases. Since interventions aimed at regulating oral biological disorders may delay the progress of liver disease, it is crucial to better comprehend this process. Oral bacteria with potential pathogenicity have been extensively studied and are closely related to several types of chronic liver diseases. Therefore, this review will systemically describe the emerging role of oral pathogenic bacteria in common liver diseases, including alcoholic liver disease (ALD), non-alcoholic steatohepatitis (NASH), non-alcoholic fatty liver disease (NAFLD), cirrhosis, autoimmune liver diseases (AILD), and liver cancer, and bring in new perspectives for future research.

Stress mechanism involved in the progression of alcoholic liver disease and the therapeutic efficacy of nanoparticles

Alcoholic liver disease (ALD) poses a significant threat to human health, with excessive alcohol intake disrupting the immunotolerant environment of the liver and initiating a cascade of pathological events. This progressive disease unfolds through fat deposition, proinflammatory cytokine upregulation, activation of hepatic stellate cells, and eventual development of end-stage liver disease, known as hepatocellular carcinoma (HCC). ALD is intricately intertwined with stress mechanisms such as oxidative stress mediated by reactive oxygen species, endoplasmic reticulum stress, and alcohol-induced gut dysbiosis, culminating in increased inflammation. While the initial stages of ALD can be reversible with diligent care and abstinence, further progression necessitates alternative treatment approaches. Herbal medicines have shown promise, albeit limited by their poor water solubility and subsequent lack of extensive exploration. Consequently, researchers have embarked on a quest to overcome these challenges by delving into the potential of nanoparticle-mediated therapy. Nanoparticle-based treatments are being explored for liver diseases that share similar mechanisms with alcoholic liver disease. It underscores the potential of these innovative approaches to counteract the complex pathogenesis of ALD, providing new avenues for therapeutic intervention. Nevertheless, further investigations are imperative to fully unravel the therapeutic potential and unlock the promise of nanoparticle-mediated therapy specifically tailored for ALD treatment.

Stress mechanism involved in the progression of alcoholic liver disease and the therapeutic efficacy of nanoparticles

Alcoholic liver disease (ALD) poses a significant threat to human health, with excessive alcohol intake disrupting the immunotolerant environment of the liver and initiating a cascade of pathological events. This progressive disease unfolds through fat deposition, proinflammatory cytokine upregulation, activation of hepatic stellate cells, and eventual development of end-stage liver disease, known as hepatocellular carcinoma (HCC). ALD is intricately intertwined with stress mechanisms such as oxidative stress mediated by reactive oxygen species, endoplasmic reticulum stress, and alcohol-induced gut dysbiosis, culminating in increased inflammation. While the initial stages of ALD can be reversible with diligent care and abstinence, further progression necessitates alternative treatment approaches. Herbal medicines have shown promise, albeit limited by their poor water solubility and subsequent lack of extensive exploration. Consequently, researchers have embarked on a quest to overcome these challenges by delving into the potential of nanoparticle-mediated therapy. Nanoparticle-based treatments are being explored for liver diseases that share similar mechanisms with alcoholic liver disease. It underscores the potential of these innovative approaches to counteract the complex pathogenesis of ALD, providing new avenues for therapeutic intervention. Nevertheless, further investigations are imperative to fully unravel the therapeutic potential and unlock the promise of nanoparticle-mediated therapy specifically tailored for ALD treatment.

Ambiguous Pathogenic Roles of Macrophages in Alcohol-Associated Liver Diseases

Alcohol-associated liver disease (ALD) represents a major public health issue worldwide and is a leading etiology of liver cirrhosis. Alcohol-related liver injuries include a range of manifestations including alcoholic hepatitis (AH), simple steatosis, steatohepatitis, hepatic fibrosis, cirrhosis and liver cancer. Liver disease occurs from several pathological disturbances such as the metabolism of ethanol, which generates reactive oxygen species (ROS) in hepatocytes, alterations in the gut microbiota, and the immune response to these changes. A common hallmark of these liver affections is the establishment of an inflammatory environment, and some (broad) anti-inflammatory approaches are used to treat AH (eg, corticosteroids). Macrophages, which represent the main innate immune cells in the liver, respond to a wide variety of (pathogenic) stimuli and adopt a large spectrum of phenotypes. This translates to a diversity of functions including pathogen and debris clearance, recruitment of other immune cells, activation of fibroblasts, or tissue repair. Thus, macrophage populations play a crucial role in the course of ALD, but the underlying mechanisms driving macrophage polarization and their functionality in ALD are complex. In this review, we explore the various populations of hepatic macrophages in alcohol-associated liver disease and the underlying mechanisms driving their polarization. Additionally, we summarize the crosstalk between hepatic macrophages and other hepatic cell types in ALD, in order to support the exploration of targeted therapeutics by modulating macrophage polarization.

Clinical Perspectives of Gut Microbiota in Patients with Chronic Kidney Disease and End-Stage Kidney Disease: Where Do We Stand?

The gut microbiota (GM) plays a vital role in human health, with increasing evidence linking its imbalance to chronic kidney disease and end-stage kidney disease. Although the exact methods underlying kidney-GM crosstalk are not fully understood, interventions targeting GM were made and lay in three aspects: diagnostic, predictive, and therapeutic interventions. While these interventions show promising results in reducing uremic toxins and inflammation, challenges remain in the form of patient-specific GM variability, potential side effects, and safety concerns. Our understanding of GMs role in kidney disease is still evolving, necessitating further research to elucidate the causal relationship and mechanistic interactions. Personalized interventions focusing on specific GM signatures could enhance patient outcomes. However, comprehensive clinical trials are needed to validate these approaches' safety, efficacy, and feasibility.

Altered urinary tryptophan metabolites in alcohol-associated liver disease

BACKGROUND

Alcohol-associated liver disease (ALD) leads to millions of deaths worldwide annually. A few potential biomarkers of ALD have been discovered through metabolomic or proteomic analysis. Tryptophan (Trp), one of nine essential amino acids, has been extensively studied and shown to play significant roles in many mammalian physiological processes. However, Trp metabolism changes in ALD are not yet fully understood. Whereas urine is an abundant and non-invasive source for disease biomarker discovery the current study investigated whether the abundance of Trp metabolites in the urine of ALD patients differs from that of healthy subjects. We also examined whether, if present in ALD, changes in urinary Trp metabolites can serve as markers for differentiating between mild/moderate and severe ALD.

METHODS

We quantified the concentration of Trp and its metabolites in urine samples of healthy controls (n = 18), patients with mild or moderate alcohol-related liver injury (non-severe ALD; n = 21), and patients with severe alcohol-associated hepatitis (severe AH; n = 25) using both untargeted and targeted metabolomics.

RESULTS

Eighteen Trp metabolites were identified and quantified from the untargeted metabolomics data. We developed a targeted metabolomics method to quantify the Trp and its metabolites and quantified 17 metabolites from the human urine samples. The data acquired in the untargeted and targeted platforms agreed and showed that the Trp concentration is not affected by the severity of ALD. However, the abundance of 10 Trp metabolites was correlated with the model for end-stage liver disease (MELD) score, with the abundance of nine metabolites significantly different between the healthy control and ALD patient groups.

CONCLUSION

We found that Trp metabolism differs between ALD patients and healthy controls even though the concentration of Trp was not affected. Two Trp metabolites, quinolinic acid and indoxyl sulfate, correlate highly with the severity of ALD.

Drinking and laboratory biomarkers, and nutritional status characterize the clinical presentation of early-stage alcohol-associated liver disease

Chronic and heavy alcohol consumption is commonly observed in alcohol use disorder (AUD). AUD often leads to alcohol-associated organ injury, including alcohol-associated liver disease (ALD). Approximately 10-20% of patients with AUD progress to ALD. Progression of ALD from the development phase to more advanced states involve the interplay of several pathways, including nutritional alterations. Multiple pathologic processes have been identified in the progression and severity of ALD. However, there are major gaps in the characterization and understanding of the clinical presentation of early-stage ALD as assessed by clinical markers and laboratory measures. Several Institutions and Universities, including the University of Louisville, in collaboration with the National Institutes of Health, have published a series of manuscripts describing early-stage ALD over the past decade. Here, we comprehensively describe early-stage ALD using the liver injury and drinking history markers, and the laboratory biomarkers (with a focus on nutrition status) that are uniquely involved in the development and progression of early-stage ALD.

A critical review of recent knowledge of alcohol's effects on the immunological response in different tissues

Alcohol misuse contributes to the dysregulation of immune responses and multiorgan dysfunction across various tissues, which are associated with higher risk of morbidity and mortality in people with alcohol use disorders. Organ-specific immune cells, including microglia in the brain, alveolar macrophages in the lungs, and Kupffer cells in the liver, play vital functions in host immune defense through tissue repair and maintenance of homeostasis. However, binge drinking and chronic alcohol misuse impair these immune cells' abilities to regulate inflammatory signaling and metabolism, thus contributing to multiorgan dysfunction. Further complicating these delicate systems, immune cell dysfunction associated with alcohol misuse is exacerbated by aging and gut barrier leakage. This critical review describes recent advances in elucidating the potential mechanisms by which alcohol misuse leads to derangements in host immunity and highlights current gaps in knowledge that may be the focus of future investigations.

Endosymbiosis in Nature and the Gut-Brain Axis

Exploring the origin of plastids is an interesting theme for study because it enhances our knowledge of the basis of photosynthesis in flora. Plastids, which are organelles, are actually the major sites of photosynthesis in eukaryotic cells. Plastids are also every chloroplast which contains cytoplasmic organelles, enabling the harvesting and conversion of light and carbon dioxide into food and energy. Plastids can be found in eukaryotic cells, and according to their structure in their membrane, they can be separated in primary (which can be found in most algae and plants) and secondary plastids (which can be found in plankton).

Alcohol use disorder as a potential risk factor for COVID-19 severity: A narrative review

In Dec. 2019-January 2020, a pneumonia illness originating in Wuhan, China, designated as coronavirus disease 2019 (COVID-19) was shown to be caused by a novel RNA coronavirus designated as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). People with advanced age, male sex, and/or underlying health conditions (obesity, type 2 diabetes, cardiovascular disease, hypertension, chronic kidney disease, and chronic lung disease) are especially vulnerable to severe COVID-19 symptoms and death. These risk factors impact the immune system and are also associated with poor health, chronic illness, and shortened longevity. However, a large percent of patients without these known risk factors also develops severe COVID-19 disease that can result in death. Thus, there must exist risk factors that promote exaggerated inflammatory and immune response to the SARS-CoV-2 virus leading to death. One such risk factor may be alcohol misuse and alcohol use disorder because these can exacerbate viral lung infections like SARS, influenza, and pneumonia. Thus, it is highly plausible that alcohol misuse is a risk factor for either increased infection rate when individuals are exposed to SARS-CoV-2 virus and/or more severe COVID-19 in infected patients. Alcohol use is a well-known risk factor for lung diseases and ARDS in SARS patients. We propose that alcohol has three key pathogenic elements in common with other COVID-19 severity risk factors: namely, inflammatory microbiota dysbiosis, leaky gut, and systemic activation of the NLRP3 inflammasome. We also propose that these three elements represent targets for therapy for severe COVID-19.

Milk Fat Globule Membrane Attenuates Acute Colitis and Secondary Liver Injury by Improving the Mucus Barrier and Regulating the Gut Microbiota

Objective

Inflammatory bowel disease (IBD) often occurs along with extraintestinal manifestations, including hepatic injury. Milk fat globule membrane (MFGM) is an active substance with a potential anti-inflammation activity. However, its alleviated effect and mechanisms in IBD as well as the IBD-induced secondary liver injury are still unclear.

Methods

C57BL/6J mice were administered with a 21-day oral gavage of MFGM, followed by 7 days of drinking water with 4% dextran sulfate sodium (DSS). Disease activity index (DAI), histological features, and cytokines of the colon and liver were evaluated. Then, RNA-seq of the colon and liver was conducted. The gut microbiota was assessed by analyzing 16S rRNA gene sequences, and finally the integrity and the function of the mucus barrier were evaluated by Alcian blue staining, real-time quantitative PCR, and ELISA.

Results

Prophylactic MFGM treatment was effective against colitis to include effects in body weight loss, DAI score, colonic length, intestinal pathology, and histological score. Additionally, prophylactic MFGM decreased the levels of interleukin (IL)-1β, IL-6, and myeloperoxidase in colonic tissue, while it increased the IL-10 level. Moreover, the gene expressions of MUC2, MUC4, Reg3b, and Reg3g associated with the production of the molecular mediator of immune response, membrane invagination, and response to protozoan were strikingly upregulated when administered with MFGM. On the other hand, the beneficial effects of MFGM were related to the enriched abundance of genera such as Faccalibacumum and Roseburia in feces samples. Consistently, the administration of MFGM was also found to alleviate DSS-induced hepatic injury. Furthermore, the glutathione transferase activity pathway was enriched in the liver of MFGM-treated mice after DSS administration. Mechanistically, prophylactic MFGM enhanced the mucosal barrier by increasing the gene levels of Reg3b and Reg3g. Meanwhile, the alleviation of MFGM on liver injury was dependent on the reduced hepatic oxidative stress.

Conclusions

MFGM attenuated colitis and hepatic injury by maintaining the mucosal barrier and bacterial community while inhibiting oxidative stress, which might be an effective therapy of hepatic injury secondary to IBD.

Gut Barrier and Microbiota in Cirrhosis

Gut microbiota and their homeostatic functions are central to the maintenance of the intestinal mucosal barrier. The gut barrier functions as a structural, biological, and immunological barrier, preventing local and systemic invasion and inflammation of pathogenic taxa, resulting in the propagation or causation of organ-specific (liver disease) or systemic diseases (sepsis) in the host. In health, commensal bacteria are involved in regulating pathogenic bacteria, sinister bacterial products, and antigens; and help control and kill pathogenic organisms by secreting antimicrobial metabolites. Gut microbiota also participates in the extraction, synthesis, and absorption of nutrient metabolites, maintains intestinal epithelial integrity and regulates the development, homeostasis, and function of innate and adaptive immune cells. Cirrhosis is associated with local and systemic immune, vascular, and inflammatory changes directly or indirectly linked to perturbations in quality and quantity of intestinal microbiota and intestinal mucosal integrity. Dysbiosis and gut barrier dysfunction are directly involved in the pathogenesis of compensated cirrhosis and the type and severity of complications in decompensated cirrhosis, such as bacterial infections, encephalopathy, extrahepatic organ failure, and progression to acute on chronic liver failure. This paper reviews the normal gut barrier, gut barrier dysfunction, and dysbiosis-associated clinical events in patients with cirrhosis. The role of dietary interventions, antibiotics, prebiotics, probiotics, synbiotics, and healthy donor fecal microbiota transplantation (FMT) to modulate the gut microbiota for improving patient outcomes is further discussed.

Immune cells in alcohol-related liver disease

Alcohol-related liver disease (ALD), which is caused by excessive alcohol consumption, is one of the most common types of liver disease and a primary cause of hepatic injury, with a disease spectrum that includes steatosis, steatohepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. Various lines of evidence have indicated that immune cells play a significant role in the inflammatory processes of ALD. On the one hand, the liver contains various resident immune cells that have been proven to perform different functions in ALD. For example, in the progression of the disease, Kupffer cells (KCs) are activated by lipopolysaccharide-Toll-like receptor 4 signaling and release various proinflammatory cytokines. Moreover, alcohol intake has been shown to depress the function of natural killer cells. Additionally, two types of unconventional T cells (natural killer T cells and mucosal-associated invariant T cells) are involved in the development of ALD. On the other hand, alcohol and many different cytokines stimulate the recruitment and infiltration of circulating immune cells (neutrophils, T cells, macrophages, and mast cells) into the liver. The neutrophils can produce proinflammatory mediators and cause the dysfunction of anti-infection processes. Additionally, alcohol intake can change the phenotype of T cells, resulting in their increased production of interleukin-17. Aside from KCs, infiltrating macrophages have also been observed in patients with ALD, but the roles of all of these cells in the progression of the disease have shown both similarities and differences. Additionally, the activated mast cells are also associated with the development of ALD. Herein, we review the diverse roles of the various immune cells in the progression of ALD.

Impact of compensated cirrhosis on survival in patients with acute-on-chronic liver failure

BACKGROUND AND AIMS

Acute-on-chronic liver failure (ACLF) is considered a main prognostic event in patients with chronic liver disease (CLD). We analyzed the 28-day and 90-day mortality in ACLF patients with or without underlying cirrhosis enrolled in the ACLF Research Consortium (AARC) database.

METHODS

A total of 1,621 patients were prospectively enrolled and 637 (39.3%) of these patients had cirrhosis. Baseline characteristics, complications and mortality were compared between patients with and without cirrhosis.

RESULTS

Alcohol consumption was more common in cirrhosis than non-cirrhosis (66.4% vs. 44.2%, p < 0.0001), while non-alcoholic fatty liver disease/cryptogenic CLD (10.9% vs 5.8%, p < 0.0001) and chronic HBV reactivation (18.8% vs 11.8%, p < 0.0001) were more common in non-cirrhosis. Only 0.8% of patients underwent liver transplantation. Overall, 28-day and 90-day mortality rates were 39.3% and 49.9%, respectively. Patients with cirrhosis had a greater chance of survival compared to those without cirrhosis both at 28-day (HR = 0.48; 95% CI 0.36-0.63, p < 0.0001) and 90-day (HR = 0.56; 95% CI 0.43-0.72, p < 0.0001), respectively. In alcohol CLD, non-cirrhosis patients had a higher 28-day (49.9% vs. 23.6%, p < 0.001) and 90-day (58.4% vs. 35.2%, p < 0.001) mortality rate than cirrhosis patients. ACLF patients with cirrhosis had longer mean survival than non-cirrhosis patients (25.5 vs. 18.8 days at 28-day and 65.2 vs. 41.2 days at 90-day). Exaggerated systemic inflammation might be the reason why non-cirrhosis patients had a poorer prognosis than those with cirrhosis after ACLF had occurred.

CONCLUSIONS

The 28-day and 90-day mortality rates of ACLF patients without cirrhosis were significantly higher than those with cirrhosis in alcoholic CLD. The presence of cirrhosis and its stage should be evaluated at baseline to guide for management. Thai Clinical Trials Registry, TCTR20191226002.

Stress and the Role of the Gut-Brain Axis in the Pathogenesis of Schizophrenia: A Literature Review

Schizophrenia is a severe neuropsychiatric disorder, and its etiology remains largely unknown. Environmental factors have been reported to play roles in the pathogenesis of schizophrenia, and one of the major environmental factors identified for this disorder is psychosocial stress. Several studies have suggested that stressful life events, as well as the chronic social stress associated with city life, may lead to the development of schizophrenia. The other factor is the gut–brain axis. The composition of the gut microbiome and alterations thereof may affect the brain and may lead to schizophrenia. The main interest of this review article is in overviewing the major recent findings on the effects of stress and the gut–brain axis, as well as their possible bidirectional effects, in the pathogenesis of schizophrenia.

Malnutrition and Alcohol-Associated Hepatitis

Malnutrition is common in alcohol-associated hepatitis (AH); almost all patients with severe AH have some component of malnutrition. The classic phenotype of malnutrition in AH is sarcopenia, but this has become more difficult to discern clinically as patients have become more obese. Patients with AH are often drinking 10 to 15 standard drinks per day. This substantial alcohol consumption becomes a major source of calories, but these are considered "empty" calories that contain little nutritional value. Malnutrition is associated with liver complications, such as hepatic encephalopathy, and worse liver outcomes. Nutrition support can improve nutrition status and reduce complications.

Role of microbial dysbiosis in carcinogenesis & cancer therapies

The human body supports a heterogeneous population of microorganisms. Every microorganism has the ability to contribute to the unique microenvironment around it. The aim of this review is to discuss the changes in the microbial population and their relative abundance across different ecosystems of the human body, the interactions within the microbial communities, metabolites they secrete to their external environment, their immunomodulatory functions, their signal transduction pathways and how these respond to environmental stimuli such as various diets, alcohol and drug consumption, smoking and finally suggest new therapeutic approaches. The microbiota may leads to cancer through inflammation mediated mechanisms which modulate immune responses, or produce carcinogenic metabolites and genotoxins, or deregulate cell proliferative signalling pathways. The identification of these molecular mechanisms in carcinogenesis may lead to better treatment strategies. In this review we have tried to explore the changes in microbial composition between cancer and normal tissues and what molecular mechanisms provide a connecting link between microbial dysbiosis and cancer.

Sea buckthorn (Hippophae rhamnoides L.) fermentation liquid protects against alcoholic liver disease linked to regulation of liver metabolome and the abundance of gut microbiota

BACKGROUND

Alcoholic liver disease (ALD) refers to liver damage caused by long-term heavy drinking, which causes oxidative stress and changes in gut microbiota. In this paper, we investigated the hepatoprotective effect of sea buckthorn fermentation liquid on ALD in mice and the interaction between ALD and gut microbiota using animal experiments and gut microbiota measurements.

RESULTS

We found that the contents of total flavonoids, total triterpenes and related short-chain fatty acids (SCFAs) in sea buckthorn fermentation liquid (SFL) were significantly greater. Liver index, kidney index, spleen index, serum indexes of liver injury - alanine aminotransferase (ALT) and spartate aminotransferase (AST), inflammatory factors in liver tissues - tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), oxidation indexes - malondialdehyde (MDA) and superoxide dismutase (SOD), and lipid metabolism indexes - high-density liptein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), and triglyceride (TG), suggested that SFL significantly ameliorates liver injury caused by alcohol. By measuring gut microbiota in mice feces samples, we found that the high-dose group of SFL reversed the declining trend of the gut microbiota Firmicutes/Bacteroidetes (F/B) ratio caused by alcohol, reducing the number of gram-negative bacteroidetes. Patescibacteria was tightly connected with the indicators of ALD. At the genus level, high-dose SFL significantly downregulated Akkermansia, Turicibacter, Alistipes and Ruminiclostridium, and improved the abundance of beneficial bacteria in Lactobacillus. In addition, Alistipes and Ruminiclostridium was closely connected with the indicators of ALD.

CONCLUSION

Sea buckthorn fermentation liquid protected against alcoholic liver disease and modulated the composition of gut microbiota. © 2020 Society of Chemical Industry.