Ecophysiological consequences of alcoholism on human gut microbiota: implications for ethanol-related pathogenesis of colon cancer

Gut Microbiome Interactions with Oxidative Stress: Mechanisms and Consequences for Health

Understanding how gut flora interacts with oxidative stress has been the subject of significant research in recent years. There is much evidence demonstrating the existence of the microbiome-oxidative stress interaction. However, the biochemical basis of this interaction is still unclear. In this narrative review, possible pathways of the gut microbiota and oxidative stress interaction are presented, among which genetic underpinnings play an important role. Trimethylamine-N-oxide, mitochondria, short-chain fatty acids, and melatonin also appear to play roles. Moreover, the relationship between oxidative stress and the gut microbiome in obesity, metabolic syndrome, chronic ethanol consumption, dietary supplements, and medications is considered. An investigation of the correlation between bacterial community features and OS parameter changes under normal and pathological conditions might provide information for the determination of new research methods. Furthermore, such research could contribute to establishing a foundation for determining the linkers in the microbiome-OS association.

Beyond a vestigial organ: effects of the appendix on gut microbiome and colorectal cancer

The role of appendectomy in the pathogenesis of colorectal cancer (CRC) is a recent topic of contention. Given that appendectomy remains one of the most commonly performed operations and a first-line management strategy of acute appendicitis, it is inherently crucial to elucidate the association between prior appendectomy and subsequent development of CRC, as there may be long-term health repercussions. In this review, we summarize the data behind the relationship of CRC in post-appendectomy patients, discuss the role of the microbiome in relation to appendectomy and CRC pathogenesis, and provide an appraisal of our current understanding of the function of the appendix. We seek to piece together the current landscape surrounding the microbiome and immunological changes in the colon post-appendectomy and suggest a direction for future research involving molecular, transcriptomic, and immunologic analysis to complement our current understanding of the alterations in gut microbiome.

Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease

To understand the dynamic interplay between the human microbiome and host during health and disease, we analyzed the microbial composition, temporal dynamics, and associations with host multi-omics, immune, and clinical markers of microbiomes from four body sites in 86 participants over 6 years. We found that microbiome stability and individuality are body-site specific and heavily influenced by the host. The stool and oral microbiome are more stable than the skin and nasal microbiomes, possibly due to their interaction with the host and environment. We identify individual-specific and commonly shared bacterial taxa, with individualized taxa showing greater stability. Interestingly, microbiome dynamics correlate across body sites, suggesting systemic dynamics influenced by host-microbial-environment interactions. Notably, insulin-resistant individuals show altered microbial stability and associations among microbiome, molecular markers, and clinical features, suggesting their disrupted interaction in metabolic disease. Our study offers comprehensive views of multi-site microbial dynamics and their relationship with host health and disease.

The Past and Future of Inflammation as a Target to Cancer Prevention

Inflammation is an essential defense mechanism in which innate immune cells are coordinately activated on encounter of harmful stimuli, including pathogens, tissue injury, and toxic compounds and metabolites to neutralize and eliminate the instigator and initiate healing and regeneration. Properly terminated inflammation is vital to health, but uncontrolled runaway inflammation that becomes chronic begets a variety of inflammatory and metabolic diseases and increases cancer risk. Making damaged tissues behave as "wounds that do not heal" and sustaining the production of growth factors whose physiologic function is tissue healing, chronic inflammation accelerates cancer emergence from premalignant lesions. In 1863, Rudolf Virchow, a leading German pathologist, suggested a possible association between inflammation and tumor formation, but it took another 140 years to fully elucidate and appreciate the tumorigenic role of inflammation. Key findings outlined molecular events in the inflammatory cascade that promote cancer onset and progression and enabled a better appreciation of when and where inflammation should be inhibited. These efforts triggered ongoing research work to discover and develop inflammation-reducing chemopreventive strategies for decreasing cancer risk and incidence.

Fibroblast Growth Factor 19 Alters Bile Acids to Induce Dysbiosis in Mice With Alcohol-Induced Liver Disease

BACKGROUND & AIMS

Excessive alcohol consumption can lead to alcohol-associated liver disease, a spectrum of conditions ranging from steatosis to fibrosis and cirrhosis. Bile acids regulate metabolic pathways by binding to cellular and nuclear receptors, and they also interact with the gut microbiome to control microbial overgrowth. Fibroblast growth factor 19 (FGF-19) is an ileum-derived hormone induced and released in response to bile acid activation of the nuclear receptor farnesoid X receptor. FGF-19 signaling is dysregulated with ethanol consumption and is increased in patients with alcoholic hepatitis. Here, we examined the effects of FGF-19 in a mouse model of chronic + binge ethanol feeding.

METHODS

After injection of adeno-associated virus-green fluorescent protein or AAV-FGF-19, female C57BL/6J mice were pair-fed a Lieber DeCarli liquid diet (5% v/v) or control diet for 10 days and were given a bolus gavage of 5% ethanol or maltose control to represent a binge drinking episode. Tissues were collected for analysis 9 hours after the binge.

RESULTS

Chronic + binge ethanol feeding induced steatosis regardless of FGF-19 expression. Interestingly, FGF-19 and ethanol resulted in significantly increased liver inflammation, as measured by Il6, Tgfβ, and Tnfα, compared with ethanol alone. Both ethanol and FGF-19 decreased bile acid synthesis, and FGF-19 significantly reduced secondary bile acids, leading to overgrowth of specific pathogenic bacteria including Enterococcus faecalis, Escherichia coli, and Clostridium perfringens.

CONCLUSIONS

Dysregulation of FGF-19 and consequent changes in bile acid synthesis and composition during alcohol consumption may be a contributing factor to alcohol-induced liver disease and dysbiosis.

Clinical and Preclinical Evidence for Gut Microbiome Mechanisms in Substance Use Disorders

Substance use disorders are a set of recalcitrant neuropsychiatric conditions that cause tremendous morbidity and mortality and are among the leading causes of loss of disability-adjusted life years worldwide. While each specific substance use disorder is driven by problematic use of a different substance, they all share a similar pattern of escalating and out-of-control substance use, continued use despite negative consequences, and a remitting/relapsing pattern over time. Despite significant advances in our understanding of the neurobiology of these conditions, current treatment options remain few and are ineffective for too many individuals. In recent years, there has been a rapidly growing body of literature demonstrating that the resident population of microbes in the gastrointestinal tract, collectively called the gut microbiome, plays an important role in modulating brain and behavior in preclinical and clinical studies of psychiatric disease. While these findings have not yet been translated into clinical practice, this remains an important and exciting avenue for translational research. In this review, we highlight the current state of microbiome-brain research within the substance use field with a focus on both clinical and preclinical studies. We also discuss potential neurobiological mechanisms underlying microbiome effects on models of substance use disorder and propose future directions to bring these findings from bench to bedside.

Longitudinal profiling of the microbiome at four body sites reveals core stability and individualized dynamics during health and disease

To understand dynamic interplay between the human microbiome and host during health and disease, we analyzed the microbial composition, temporal dynamics, and associations with host multi-omics, immune and clinical markers of microbiomes from four body sites in 86 participants over six years. We found that microbiome stability and individuality are body-site-specific and heavily influenced by the host. The stool and oral microbiome were more stable than the skin and nasal microbiomes, possibly due to their interaction with the host and environment. Also, we identified individual-specific and commonly shared bacterial taxa, with individualized taxa showing greater stability. Interestingly, microbiome dynamics correlated across body sites, suggesting systemic coordination influenced by host-microbial-environment interactions. Notably, insulin-resistant individuals showed altered microbial stability and associations between microbiome, molecular markers, and clinical features, suggesting their disrupted interaction in metabolic disease. Our study offers comprehensive views of multi-site microbial dynamics and their relationship with host health and disease.

Study Highlights

The stability of the human microbiome varies among individuals and body sites.Highly individualized microbial genera are more stable over time.At each of the four body sites, systematic interactions between the environment, the host and bacteria can be detected.Individuals with insulin resistance have lower microbiome stability, a more diversified skin microbiome, and significantly altered host-microbiome interactions.

The adolescent and young adult microbiome and its association with substance use: a scoping review

AIMS

The microbiome is a critical factor in health throughout human development. The aims of this scoping review are to (i) elucidate the differences between the youth (post-natal day 21-65 for rodents, 2-7 years for non-human primates, and 10-25 years for humans) microbiome with other life stages and (ii) identify youth-specific microbial changes associated with substance use.

METHODS

Peer-reviewed studies published up to May 2023 were identified in PubMed and SCOPUS and included gut and oral microbiome studies from rodents, non-human primates, and humans (N = 1733). Twenty-six articles were determined eligible based on inclusion criteria (aim 1: n = 19, aim 2: n = 7).

RESULTS

The adolescent and young adult oral and gut microbiomes are distinct compared to other life stages, within both non-human and human models. While there is limited research in this area, the microbiome appears to be vulnerable to substance use exposure earlier in life, including substances commonly initiated and escalated during adolescence and young adulthood (i.e. alcohol, cannabis, and tobacco).

CONCLUSIONS

Studies across the lifespan indicate that adolescence and young adulthood are distinct periods of development, where the microbiome is sensitive to exposures, including substance use. There is a need for more studies focused on the adolescent and young adult microbiome and substance use, as well as focused on the oral microbiome during this developmental period. Understanding the gut and oral microbiome during adolescence and young adulthood may provide insight into the pathophysiology of substance use disorders.

Microbiome Dysbiosis, Dietary Intake and Lifestyle-Associated Factors Involve in Epigenetic Modulations in Colorectal Cancer: A Narrative Review

Background: Colorectal cancer is the second cause of cancer mortality and the third most commonly diagnosed cancer worldwide. Current data available implicate epigenetic modulations in colorectal cancer development. The health of the large bowel is impacted by gut microbiome dysbiosis, which may lead to colon and rectum cancers. The release of microbial metabolites and toxins by these microbiotas has been shown to activate epigenetic processes leading to colorectal cancer development. Increased consumption of a 'Westernized diet' and certain lifestyle factors such as excessive consumption of alcohol have been associated with colorectal cancer.Purpose: In this review, we seek to examine current knowledge on the involvement of gut microbiota, dietary factors, and alcohol consumption in colorectal cancer development through epigenetic modulations.Methods: A review of several published articles focusing on the mechanism of how changes in the gut microbiome, diet, and excessive alcohol consumption contribute to colorectal cancer development and the potential of using these factors as biomarkers for colorectal cancer diagnosis.Conclusions: This review presents scientific findings that provide a hopeful future for manipulating gut microbiome, diet, and alcohol consumption in colorectal cancer patients' management and care.

Ethanologenesis from glycerol by the gut acetogen Blautia schinkii

The human gut is an anoxic environment that harbours a multitude of microorganisms that not only contribute to food digestion. The microbiome is also involved in malfunctions such as diseases, inflammation processes or development of obesity, but it is also involved in processes that increase the human well-being. Both, the good and the bad, are mediated by fermentation end products of bacterial metabolism, among others. However, despite a steadily growing knowledge of 'who lives out there', little in known of 'what do they do out there'. The genus Blautia is commonly found in the gut and associated with human well-being, but the exploration of their metabolic potential has just started. We demonstrate that B. schinkii grows on glycerol by producing acetate and ethanol. Transcriptome studies and biochemical analyses revealed a glycerol dehydrogenase and dihydroxyacetone kinase that funnel the substrate into glycolysis. Consequently, cells also grew on dihydroxyacetone. Cells could be adapted to grow at high (up to 1.5 M) glycerol concentrations but then only ethanol was formed. Ethanol production from glycerol is not only of relevance for the human host but also for potential bioindustrial production of bioethanol from waste glycerol.

Disease-specific loss of microbial cross-feeding interactions in the human gut

Many gut microorganisms critical to human health rely on nutrients produced by each other for survival; however, these cross-feeding interactions are still challenging to quantify and remain poorly characterized. Here, we introduce a Metabolite Exchange Score (MES) to quantify those interactions. Using metabolic models of prokaryotic metagenome-assembled genomes from over 1600 individuals, MES allows us to identify and rank metabolic interactions that are significantly affected by a loss of cross-feeding partners in 10 out of 11 diseases. When applied to a Crohn's disease case-control study, our approach identifies a lack of species with the ability to consume hydrogen sulfide as the main distinguishing microbiome feature of disease. We propose that our conceptual framework will help prioritize in-depth analyses, experiments and clinical targets, and that targeting the restoration of microbial cross-feeding interactions is a promising mechanism-informed strategy to reconstruct a healthy gut ecosystem.

Identifying and ranking causal microbial biomarkers for colorectal cancer at different cancer subsites and stages: a Mendelian randomization study

Introduction

The gut microbiome is directly involved in colorectal carcinogenesis, but much of the epidemiological evidence for the effect of the gut microbiome on colorectal cancer (CRC) risk comes from observational studies, and it is unclear whether identified microbial alterations are the cause or consequence of CRC development.

Methods

Univariate Mendelian randomization (MR) analysis and multivariate MR analysis based on Bayesian model averaging were performed to comprehensively explore the microbial risk factors associated with CRC. The Network Module Structure Shift method was used to identify microbial biomarkers associated with CRC. Mediation analysis was used to explore the dietary habits-microbiota-CRC pathway.

Results

The results of the four methods showed that 9 bacteria had a robust causal relationship with the development of CRC. Among them, Streptococcus thermophilus reduced the risk of CRC; Eubacterium ventriosum and Streptococcus were beneficial bacteria of malignant tumors of colon (CC); Erysipelotrichaceae was a protective factor for malignant tumors of rectal (CR); Bacteroides ovatus was a risk factor for benign tumors. Finally, the mediation analysis revealed 10 pathways by which dietary regulation bacteria affected the risk of CRC, including alcohol consumption increased the risk of CC by reducing the abundance of Eubacterium ventriosum (mediated proportion: 43.044%), and the mediated proportion of other pathways was 7.026%-34.22%.

Discussion

These findings will contribute to the understanding of the different carcinogenic mechanisms of intestinal flora in the colon and rectum and the risk of tumor transformation, thereby aiding CRC prevention, early screening, and the development of future strategies to reduce CRC risk.

Alcohol-associated bowel disease: new insights into pathogenesis

Excessive alcohol drinking can cause pathological changes including carcinogenesis in the digestive tract from mouth to large intestine, but the underlying mechanisms are not fully understood. In this review, we discuss the effects of alcohol on small and large intestinal functions, such as leaky gut, dysbiosis and alterations of intestinal epithelium and gut immune dysfunctions, commonly referred to as alcohol-associated bowel disease (ABD). To date, detailed mechanistic insights into ABD are lacking. Accumulating evidence suggests a pathogenic role of ethanol metabolism in dysfunctions of the intestinal tract. Ethanol metabolism generates acetaldehyde and acetate, which could potentially promote functional disruptions of microbial and host components of the intestinal barrier along the gastrointestinal tract. The potential involvement of acetaldehyde and acetate in the pathogenesis of the underlying ABD, including cancer, is discussed. We also highlight some gaps in knowledge existing in the field of ABD. Finally, we discuss future directions in exploring the role of acetaldehyde and acetate generated during chronic alcohol intake in various pathologies affecting different sites of the intestinal tract.

Enterocloster alcoholdehydrogenati sp. nov., a Novel Bacterial Species Isolated from the Feces of a Patient with Alcoholism

Strain C5-48T, an anaerobic intestinal bacterium that potentially accumulates acetaldehyde at levels exceeding its minimum mutagenic concentration (50 µM) in the colon and rectum, was isolated from the feces of a patient with alcoholism. The 16S rRNA gene sequence of strain C5-48T showed high similarity to the corresponding sequences of Lachnoclostridium edouardi Marseille-P3397T (95.7%) and Clostridium fessum SNUG30386T (94.7%). However, phylogenetic analysis using the sequences of the 16S rRNA, rpoB, and hsp60 genes and whole-genome analysis strongly suggested that C5-48T should be included in the genus Enterocloster. The novelty of strain C5-48T was further confirmed by comprehensive average nucleotide identity (ANI) calculations based on its whole-genome sequence, which showed appreciable ANI values with known Enterocloster species (e.g., 74.3% and 73.4% with Enterocloster bolteae WAL 16351T and Enterocloster clostridioformis ATCC 25537T, respectively). The temperature range for growth of strain C5-48T was 15-37 °C with an optimum of 37 °C. The pH range for growth was 5.5-10.5 with an optimum of 7.5. The major constituents of the cell membrane lipids of strain C5-48T were 16:0, 14:0, and 18:1 ω7c dimethyl acetal fatty acids. On the basis of the genotypic and phenotypic properties, Enterocloster alcoholdehydrogenati sp. nov. is proposed, with the type strain C5-48T (= JCM 33305T = DSM 109474T).

Microbiome Alterations in Alcohol Use Disorder and Alcoholic Liver Disease

Microbiome alterations are emerging as one of the most important factors that influence the course of alcohol use disorder (AUD). Recent advances in bioinformatics enable more robust and accurate characterization of changes in the composition of the microbiome. In this study, our objective was to provide the most comprehensive and up-to-date evaluation of microbiome alterations associated with AUD and alcoholic liver disease (ALD). To achieve it, we have applied consistent, state of art bioinformatic workflow to raw reads from multiple 16S rRNA sequencing datasets. The study population consisted of 122 patients with AUD, 75 with ALD, 54 with non-alcoholic liver diseases, and 260 healthy controls. We have found several microbiome alterations that were consistent across multiple datasets. The most consistent changes included a significantly lower abundance of multiple butyrate-producing families, including Ruminococcaceae, Lachnospiraceae, and Oscillospiraceae in AUD compared to HC and further reduction of these families in ALD compared with AUD. Other important results include an increase in endotoxin-producing Proteobacteria in AUD, with the ALD group having the largest increase. All of these alterations can potentially contribute to increased intestinal permeability and inflammation associated with AUD and ALD.

Using whole-genome sequencing (WGS) to plot colorectal cancer-related gut microbiota in a population with varied geography

BACKGROUND

Colorectal cancer (CRC) is a multifactorial disease with genetic and environmental factors. Regional differences in risk factors are an important reason for the different incidences of CRC in different regions.

OBJECTIVE

The goal was to clarify the intestinal microbial composition and structure of CRC patients in different regions and construct CRC risk prediction models based on regional differences.

METHODS

A metagenomic dataset of 601 samples from 6 countries in the GMrepo and NCBI databases was collected. All whole-genome sequencing (WGS) data were annotated for species by MetaPhlAn2. We obtained the relative abundance of species composition at the species level and genus level. The MicrobiotaProcess package was used to visualize species composition and PCA. LEfSe analysis was used to analyze the differences in the datasets in each region. Spearman correlation analysis was performed for CRC differential species. Finally, the CRC risk prediction model was constructed and verified in each regional dataset.

RESULTS

The composition of the intestinal bacterial community varied in different regions. Differential intestinal bacteria of CRC in different regions are inconsistent. There was a common diversity of bacteria in all six countries, such as Peptostreptococcus stomatis and Fusobacterium nucleatum at the species level. Peptostreptococcus stomatis (species level) and Peptostreptococcus (genus level) are important CRC-related bacteria that are related to other bacteria in different regions. Region has little influence on the accuracy of the CRC risk prediction model. Peptostreptococcus stomatis is an important variable in CRC risk prediction models in all regions.

CONCLUSION

Peptostreptococcus stomatis is a common high-risk pathogen of CRC worldwide, and it is an important variable in CRC risk prediction models in all regions. However, regional differences in intestinal bacteria had no significant impact on the accuracy of the CRC risk prediction model.

Microbe-based therapies for colorectal cancer: Advantages and limitations

Cancer is one of the leading global causes of death in both men and women. Colorectal cancer (CRC) alone accounts for ∼10 % of total new global cases and poses an over 4% lifetime risk of developing cancer. Recent advancements in the field of biotechnology and microbiology concocted novel microbe-based therapies to treat various cancers, including CRC. Microbes have been explored for human use since centuries, especially for the treatment of various ailments. The utility of microbes in cancer therapeutics is widely explored, and various bacteria, fungi, and viruses are currently in use for the development of cancer therapeutics. The human gut hosts about 100 trillion microbes that release their metabolites in active, inactive, or dead conditions. Microbial secondary metabolites, proteins, immunotoxins, and enzymes are used to target cancer cells to induce cell cycle arrest, apoptosis, and death. Various approaches, such as dietary interventions, the use of prebiotics and probiotics, and fecal microbiota transplantation have been used to modulate the gut microbiota in order to prevent or treat CRC pathogenesis. The present review highlights the role of the gut microbiota in CRC precipitation, the potential mechanisms and use of microorganisms as CRC biomarkers, and strategies to modulate microbiota for the prevention and treatment of CRC.

Reduced alcohol preference and intake after fecal transplant in patients with alcohol use disorder is transmissible to germ-free mice

Alcohol use disorder is a major cause of morbidity, which requires newer treatment approaches. We previously showed in a randomized clinical trial that alcohol craving and consumption reduces after fecal transplantation. Here, to determine if this could be transmitted through microbial transfer, germ-free male C57BL/6 mice received stool or sterile supernatants collected from the trial participants pre-/post-fecal transplant. We found that mice colonized with post-fecal transplant stool but not supernatants reduced ethanol acceptance, intake and preference versus pre-fecal transplant colonized mice. Microbial taxa that were higher in post-fecal transplant humans were also associated with lower murine alcohol intake and preference. A majority of the differentially expressed genes (immune response, inflammation, oxidative stress response, and epithelial cell proliferation) occurred in the intestine rather than the liver and prefrontal cortex. These findings suggest a potential for therapeutically targeting gut microbiota and the microbial-intestinal interface to alter gut-liver-brain axis and reduce alcohol consumption in humans.

Suppression of colonic oxidative stress caused by chronic ethanol administration and attenuation of ethanol-induced colitis and gut leakiness by oral administration of sesaminol in mice

Chronic consumption of excess ethanol is one of the major risk factors for colorectal cancer (CRC), and the pathogenesis of ethanol-related CRC (ER-CRC) involves ethanol-induced oxidative-stress and inflammation in the colon and rectum, as well as gut leakiness. In this study, we hypothesised that oral administration of sesaminol, a sesame lignan, lowers the risk of ER-CRC because we found that it is a strong antioxidant with very low prooxidant activity. This hypothesis was examined using a mouse model, in which 2.0% v/v ethanol was administered ad libitum for 2 weeks with or without oral gavage with sesaminol (2.5 mg per day). Oral sesaminol administration suppressed the ethanol-induced colonic lesions and the ethanol-induced elevation of the colonic levels of oxidative stress markers (8-hydroxy-2'-deoxyguanosine, malondialdehyde, and 4-hydroxyalkenals). It consistently suppressed the chronic ethanol-induced expressions of cytochrome P450-2E1 and inducible nitric oxide synthase and upregulated heme oxygenase-1 expression, probably via the nuclear factor erythroid-derived 2-like 2 pathway in the mouse colon. Oral sesaminol administration also suppressed the chronic ethanol-induced elevation of colonic inflammation marker levels, such as those of tumour necrosis factor-α, interleukin-6, and monocyte chemoattractant protein-1, probably via the nuclear factor-kappa B pathway. Moreover, it prevented the chronic ethanol-induced gut leakiness by restoring tight junction proteins, giving rise to lower plasma endotoxin levels compared with those of ethanol-administered mice. All of these results suggest that dietary supplementation of sesaminol may lower the risk of ER-CRC by suppressing each of the above-mentioned steps in ER-CRC pathogenesis.

Interaction between microbiota and immunity and its implication in colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancer-related death in the world. Besides genetic causes, colonic inflammation is one of the major risk factors for CRC development, which is synergistically regulated by multiple components, including innate and adaptive immune cells, cytokine signaling, and microbiota. The complex interaction between CRC and the gut microbiome has emerged as an important area of current CRC research. Metagenomic profiling has identified a number of prominent CRC-associated bacteria that are enriched in CRC patients, linking the microbiota composition to colitis and cancer development. Some microbiota species have been reported to promote colitis and CRC development in preclinical models, while a few others are identified as immune modulators to induce potent protective immunity against colitis and CRC. Mechanistically, microbiota regulates the activation of different immune cell populations, inflammation, and CRC via crosstalk between innate and adaptive immune signaling pathways, including nuclear factor kappa B (NF-κB), type I interferon, and inflammasome. In this review, we provide an overview of the potential interactions between gut microbiota and host immunity and how their crosstalk could synergistically regulate inflammation and CRC, thus highlighting the potential roles and mechanisms of gut microbiota in the development of microbiota-based therapies to prevent or alleviate colitis and CRC.

The Beneficial Effects of Natural Extracts and Bioactive Compounds on the Gut-Liver Axis: A Promising Intervention for Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a major cause of morbidity and mortality worldwide. It can cause fatty liver (steatosis), steatohepatitis, fibrosis, cirrhosis, and liver cancer. Alcohol consumption can also disturb the composition of gut microbiota, increasing the composition of harmful microbes and decreasing beneficial ones. Restoring eubiosis or preventing dysbiosis after alcohol consumption is an important strategy in treating ALD. Plant natural products and polyphenolic compounds exert beneficial effects on several metabolic disorders associated with ALD. Natural products and related phytochemicals act through multiple pathways, such as modulating gut microbiota, improving redox stress, and anti-inflammation. In the present review article, we gather information on natural extract and bioactive compounds on the gut-liver axis for the possible treatment of ALD. Supplementation with natural extracts and bioactive compounds promoted the intestinal tight junction, protected against the alcohol-induced gut leakiness and inflammation, and reduced endotoxemia in alcohol-exposed animals. Taken together, natural extracts and bioactive compounds have strong potential against ALD; however, further clinical studies are still needed.

Identification of a protective Bacteroides strain of alcoholic liver disease and its synergistic effect with pectin

The depletion of Bacteroides in the gut is closely correlated with the progression of alcoholic liver disease (ALD). This study aimed to identify Bacteroides strains with protective effects against ALD and evaluate the synergistic effects of Bacteroides and pectin in this disease. Mice were fed Lieber-DeCarli alcohol diet to establish an experimental ALD model and pre-treated with 4 Bacteroides strains. The severity of the liver injury, hepatic steatosis, and inflammation was evaluated through histological and biochemical assays. We found that Bacteroides fragilis ATCC25285 had the best protective effects against ALD strains by alleviating both ethanol-induced liver injury and steatosis. B. fragilis ATCC25285 could counteract inflammatory reactions in ALD by producing short-chain fat acids (SCFAs) and enhancing the intestinal barrier. In the subsequent experiment, the synbiotic combination of B. fragilis ATCC25285 and pectin was evaluated and the underlying mechanisms were investigated by metabolomic and microbiome analyses. The combination elicited superior anti-ALD effects than the individual agents used alone. The synergistic effects of B. fragilis ATCC25285 and pectin were driven by modulating gut microbiota, improving tryptophan metabolism, and regulating intestinal immune function. Based on our findings, the combination of B. fragilis ATCC25285 and pectin can be considered a potential treatment for ALD. KEY POINTS: • B. fragilis ATCC25285 was identified as a protective Bacteroides strain against ALD. • The synbiotic combination of B. fragilis and pectin has better anti-ALD effects. • The synbiotic combination modulates gut microbiota and tryptophan metabolism.

Gut Microbiome Dysbiosis in Alcoholism: Consequences for Health and Recovery

Since the mid 1980's, the impact of gastrointestinal (GI) microbiome changes during alcohol use disorder has been an area of significant interest. This work has resulted in the identification of specific changes in the abundance of certain members of the GI microbiome and the role these changes play in a variety of alcohol related disorders (i.e. alcoholic liver disease). Interestingly, some findings suggest a possible role for the GI microbiome in alcohol addiction or withdrawal. Unfortunately, there is a significant gap in knowledge in this area. Here we describe differences in the GI microbiome of alcoholic and non-alcoholic individuals and discuss the possible impact of microbes on the gut-brain axis, which could impact alcohol related behaviors (i.e. addiction). Understanding the role of the GI microbiome in alcohol related disorders will potentially lead to the development of successful microbiome-targeted therapeutics to help mitigate these disorders.

TLR4 Deficiency Affects the Microbiome and Reduces Intestinal Dysfunctions and Inflammation in Chronic Alcohol-Fed Mice

Chronic alcohol abuse causes an inflammatory response in the intestinal tract with damage to the integrity of the mucosa and epithelium, as well as dysbiosis in the gut microbiome. However, the role of gut bacteria in ethanol effects and how these microorganisms interact with the immune system are not well understood. The aim of the present study was to evaluate if TLR4 alters the ethanol-induced intestinal inflammatory response, and whether the response of this receptor affects the gut microbiota profile. We analyzed the 16S rRNA sequence of the fecal samples from wild-type (WT) and TLR4-knockout (TLR4-KO) mice with and without ethanol intake for 3 months. The results demonstrated that chronic ethanol consumption reduces microbiota diversity and causes dysbiosis in WT mice. Likewise, ethanol upregulates several inflammatory genes (IL-1β, iNOS, TNF-α) and miRNAs (miR-155-5p, miR-146a-5p) and alters structural and permeability genes (INTL1, CDH1, CFTR) in the colon of WT mice. Our results further demonstrated that TLR4-KO mice exhibit a different microbiota that can protect against the ethanol-induced activation of the immune system and colon integrity dysfunctions. In short, our results reveal that TLR4 is a key factor for determining the gut microbiota, which can participate in dysbiosis and the inflammatory response induced by alcohol consumption.

The Role of Diet and Lifestyle in Early-Onset Colorectal Cancer: A Systematic Review

Simple Summary

This systematic review sifted through the exogenous dietary and lifestyle risk factors associated with early-onset colorectal cancer, going through the putative involvement of these exogenous risk factors in epigenetic and microbiota modifications. Given the burden of early-onset colorectal cancer and its globally increasing trend with scant literature on its pathogenesis, we believe it would be of benefit to highlight the importance of further systematic and large studies. Indeed, dietary and lifestyle modification could complement colorectal screening for early-onset colorectal cancer prevention.

Abstract

The incidence of early-onset colorectal cancer, defined as colorectal cancer occurring in young adults under the age of 50, is increasing globally. Knowledge of the etiological factors in young adults is far from complete. Questionable eoCRCs’ exogenous factors are represented by processed meat, sugary drinks, alcohol, Western dietary pattern, overweight and obesity, physical inactivity, and smoking, though with heterogeneous results. Therefore, we performed a systematic review to summarize the current evidence on the role of diet and lifestyle as eoCRC risk factors. We systematically searched PubMed, Scopus, and EMBASE up to July 2021, for original studies evaluating diet, alcohol, physical activity, BMI, and smoking in eoCRC and included twenty-six studies. Indeed, the exogenous factors could represent modifiable key factors, whose recognition could establish areas of future interventions through public health strategies for eoCRC primary prevention. Additionally, we discussed the role of additional non-modifiable risk factors, and of epigenetic regulation and microbiota as mediators of the eoCRC triggered by diet and lifestyle.

A New Perspective on Fish Oil: The Prevention of Alcoholic Liver Disease

The mechanisms of alcoholic liver diseases (ALD) are very complex and interrelated, including abnormal lipid metabolism, oxidative stress, and gut-derived endotoxin pathway. On the other hand, fish oil is rich in n-3 polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which decrease blood triglyceride concentration in hypertriglycemia patients and show protective effects against fatty liver. However, there is limited evidence from studies of the relationship between fish oil and ALD based on the viewpoint of the intestinal integrity and microflora. Therefore, this review discusses the mechanism of amelioration for ALD by fish oil. Based on our previous studies, partial replacement of olive oil by fish oil in alcohol-containing liquid diet ameliorated the liver damage including fatty liver and inflammation in rats. Based on these results, the mechanisms of hepatoprotective effects due to fish oil substitution were discussed in three parts, such as regulating lipid metabolism, decreasing oxidative stress and maintaining intestinal health. First of all, we found that fish oil substitution increased plasma adiponectin levels, and then increasing MCAD and CPT-1 mRNA levels to accelerate fatty acid oxidation in liver, then further prevent ethanol-induced hepatosteatosis in rats with chronic alcohol-feeding. Fish oil replacement also enhanced hepatic autophagy flux, which enhanced lipid degradation, then inhibited lipid accumulation in liver. Secondly, the appreciable proportion of fish oil decreased lipid peroxidation by reducing the protein expression of cytochrome p450 2E1 in chronic alcohol-feeding rats. We also speculated that the appropriate proportion of n-6 and n-3 PUFAs is very important for preventing alcoholic liver disease. At last, substituting fish oil for olive oil normalized the intestinal permeability and fecal microbiota composition, thus providing a low plasma endotoxin level and inflammatory responses, which exert ameliorative effects on ethanol-induced liver injuries in rats.

Emerging Evidence on the Effects of Dietary Factors on the Gut Microbiome in Colorectal Cancer

Dietary factors have important role in modulating the gut microbiome, which in-turn regulates the molecular events in colonic mucosa. The composition and resulting metabolism of the gut microbiome are decisive factors in colorectal cancer (CRC) tumorigenesis. Altered gut microbiome is associated with impaired immune response, and the release of carcinogenic or genotoxic substances which are the major microbiome-induced mechanisms implicated in CRC pathogenesis. Diets low in dietary fibers and phytomolecules as well as high in red meat are important dietary changes which predispose to CRC. Dietary fibers which reach the colon in an undigested form are further metabolized by the gut microbiome into enterocyte friendly metabolites such as short chain fatty acid (SCFA) which provide anti-inflammatory and anti-proliferative effects. Healthy microbiome supported by dietary fibers and phytomolecules could decrease cell proliferation by regulating the epigenetic events which activate proto-oncogenes and oncogenic pathways. Emerging evidence show that predominance of microbes such as Fusobacterium nucleatum can predispose the colonic mucosa to malignant transformation. Dietary and lifestyle modifications have been demonstrated to restrict the growth of potentially harmful opportunistic organisms. Synbiotics can protect the intestinal mucosa by improving immune response and decreasing the production of toxic metabolites, oxidative stress and cell proliferation. In this narrative review, we aim to update the emerging evidence on how diet could modulate the gut microbial composition and revive colonic epithelium. This review highlights the importance of healthy plant-based diet and related supplements in CRC prevention by improving the gut microbiome.

Hidden Role of Gut Microbiome Dysbiosis in Schizophrenia: Antipsychotics or Psychobiotics as Therapeutics?

Schizophrenia is a chronic, heterogeneous neurodevelopmental disorder that has complex symptoms and uncertain etiology. Mounting evidence indicates the involvement of genetics and epigenetic disturbances, alteration in gut microbiome, immune system abnormalities, and environmental influence in the disease, but a single root cause and mechanism involved has yet to be conclusively determined. Consequently, the identification of diagnostic markers and the development of psychotic drugs for the treatment of schizophrenia faces a high failure rate. This article surveys the etiology of schizophrenia with a particular focus on gut microbiota regulation and the microbial signaling system that correlates with the brain through the vagus nerve, enteric nervous system, immune system, and production of postbiotics. Gut microbially produced molecules may lay the groundwork for further investigations into the role of gut microbiota dysbiosis and the pathophysiology of schizophrenia. Current treatment of schizophrenia is limited to psychotherapy and antipsychotic drugs that have significant side effects. Therefore, alternative therapeutic options merit exploration. The use of psychobiotics alone or in combination with antipsychotics may promote the development of novel therapeutic strategies. In view of the individual gut microbiome structure and personalized response to antipsychotic drugs, a tailored and targeted manipulation of gut microbial diversity naturally by novel prebiotics (non-digestible fiber) may be a successful alternative therapeutic for the treatment of schizophrenia patients.

Hidden Role of Gut Microbiome Dysbiosis in Schizophrenia: Antipsychotics or Psychobiotics as Therapeutics?

Schizophrenia is a chronic, heterogeneous neurodevelopmental disorder that has complex symptoms and uncertain etiology. Mounting evidence indicates the involvement of genetics and epigenetic disturbances, alteration in gut microbiome, immune system abnormalities, and environmental influence in the disease, but a single root cause and mechanism involved has yet to be conclusively determined. Consequently, the identification of diagnostic markers and the development of psychotic drugs for the treatment of schizophrenia faces a high failure rate. This article surveys the etiology of schizophrenia with a particular focus on gut microbiota regulation and the microbial signaling system that correlates with the brain through the vagus nerve, enteric nervous system, immune system, and production of postbiotics. Gut microbially produced molecules may lay the groundwork for further investigations into the role of gut microbiota dysbiosis and the pathophysiology of schizophrenia. Current treatment of schizophrenia is limited to psychotherapy and antipsychotic drugs that have significant side effects. Therefore, alternative therapeutic options merit exploration. The use of psychobiotics alone or in combination with antipsychotics may promote the development of novel therapeutic strategies. In view of the individual gut microbiome structure and personalized response to antipsychotic drugs, a tailored and targeted manipulation of gut microbial diversity naturally by novel prebiotics (non-digestible fiber) may be a successful alternative therapeutic for the treatment of schizophrenia patients.

Streptococcus, the Predominant Bacterium to Predict the Severity of Liver Injury in Alcoholic Liver Disease

Background

New evidence implies that the imbalance of gut microbiota is associated with the progression of alcoholic liver disease (ALD) and that the composition of gut microbiota is altered in ALD patients. However, the predominant bacterium in patients involved in the progress of ALD has not been identified. The purpose of this study is to investigate the predominant bacterium in the early and end-stages of ALD as well as the relationship between the bacterium and the degree of liver injury.

Methods

We enrolled 21 alcoholic fatty liver (AFL) patients, 17 alcoholic liver cirrhosis (ALC) patients and 27 healthy controls, and sequenced the 16S rRNA gene of their fecal microbiota. The gut microbiota composition and its relationship with the indicators of clinical hepatic function were assessed using canonical correspondence analysis (CCA), spearman correlation heatmap and multivariate association with linear (MaAsLin) Models.

Results

The composition and structure of gut microbiota changed greatly in different stages of ALD, and the degree of disorder was aggravated with the progression of ALD, even in the early stage. Moreover, the relative abundance of Streptococcus was highly enriched only in patients with ALC (P <0.001), and positively correlated with AST level (P = 0.029). The abundance of Streptococcus distinguished the liver injury of ALC patients from the controls with an area under the receiver-operating characteristic curve (AUC) of 0.877 (P < 0.001).

Conclusions

These findings indicate that the imbalance of gut microbiota exists at the early and end-stages of ALD, and the degree of disorder is aggravated with the progression of ALD. Streptococcus, as the predominant bacterium, may be a microbiological marker to evaluate the severity of liver injury in ALD patients.

Association between alcohol consumption and oesophageal microbiota in oesophageal squamous cell carcinoma

BACKGROUND

Microbiota has been reported to play a role in cancer patients. Nevertheless, little is known about the association between alcohol consumption and resultant changes in the diversity and composition of oesophageal microbiota in oesophageal squamous cell carcinoma (ESCC).

METHODS

We performed a hospital-based retrospective study of 120 patients with pathologically diagnosed primary ESCC. The relevant information for all study participants were collected through a detailed questionnaire. The differences in adjacent tissues between non-drinkers and drinkers were explored using 16S rRNA gene sequencing. Raw sequencing data were imported into QIIME 2 to analyse the diversity and abundance of microbiota. Linear discriminant analysis effect size (LEfSe) and unconditional logistic regression were performed to determine the bacterial taxa that were associated with drinking.

RESULTS

The Shannon diversity index and Bray-Curtis distance of oesophageal microbiota were significantly different among drinkers(P < 0.05). The alcohol-related bacteria were primarily from the orders Clostridiales, Gemellales and Pasteurellales, family Clostridiaceae, Lanchnospiraceae, Helicobacteraceae, Alcaligenaceae, Bacteroidaceae, Pasteurellaceae and Gemellaceae; genus Clostridium, Helicobacter, Catonella, Bacteroides, Bacillus, Moraxella, and Bulleidia; and species B. moorei and longum (genus Bifidobacterium). In addition, the diversity and abundance of these microbiota were observed to be affected by the age, residential districts of the patients, and sampling seasons. Moreover, the higher the frequency and years of alcohol consumption, the lower was the relative abundance of genus Catonella that was observed.

CONCLUSION

Alcohol consumption is associated with alterations in both the diversity and composition the of the oesophageal microbiota in ESCC patients.

Translational Approaches with Antioxidant Phytochemicals against Alcohol-Mediated Oxidative Stress, Gut Dysbiosis, Intestinal Barrier Dysfunction, and Fatty Liver Disease

Emerging data demonstrate the important roles of altered gut microbiomes (dysbiosis) in many disease states in the peripheral tissues and the central nervous system. Gut dysbiosis with decreased ratios of Bacteroidetes/Firmicutes and other changes are reported to be caused by many disease states and various environmental factors, such as ethanol (e.g., alcohol drinking), Western-style high-fat diets, high fructose, etc. It is also caused by genetic factors, including genetic polymorphisms and epigenetic changes in different individuals. Gut dysbiosis, impaired intestinal barrier function, and elevated serum endotoxin levels can be observed in human patients and/or experimental rodent models exposed to these factors or with certain disease states. However, gut dysbiosis and leaky gut can be normalized through lifestyle alterations such as increased consumption of healthy diets with various fruits and vegetables containing many different kinds of antioxidant phytochemicals. In this review, we describe the mechanisms of gut dysbiosis, leaky gut, endotoxemia, and fatty liver disease with a specific focus on the alcohol-associated pathways. We also mention translational approaches by discussing the benefits of many antioxidant phytochemicals and/or their metabolites against alcohol-mediated oxidative stress, gut dysbiosis, intestinal barrier dysfunction, and fatty liver disease.

Mining microbes for mental health: Determining the role of microbial metabolic pathways in human brain health and disease

There is increasing knowledge regarding the role of the microbiome in modulating the brain and behaviour. Indeed, the actions of microbial metabolites are key for appropriate gut-brain communication in humans. Among these metabolites, short-chain fatty acids, tryptophan, and bile acid metabolites/pathways show strong preclinical evidence for involvement in various aspects of brain function and behaviour. With the identification of neuroactive gut-brain modules, new predictive tools can be applied to existing datasets. We identified 278 studies relating to the human microbiota-gut-brain axis which included sequencing data. This spanned across psychiatric and neurological disorders with a small number also focused on normal behavioural development. With a consistent bioinformatics pipeline, thirty-five of these datasets were reanalysed from publicly available raw sequencing files and the remainder summarised and collated. Among the reanalysed studies, we uncovered evidence of disease-related alterations in microbial metabolic pathways in Alzheimer's Disease, schizophrenia, anxiety and depression. Amongst studies that could not be reanalysed, many sequencing and technical limitations hindered the discovery of specific biomarkers of microbes or metabolites conserved across studies. Future studies are warranted to confirm our findings. We also propose guidelines for future human microbiome analysis to increase reproducibility and consistency within the field.

Alteration of oxidative-stress and related marker levels in mouse colonic tissues and fecal microbiota structures with chronic ethanol administration: Implications for the pathogenesis of ethanol-related colorectal cancer

Chronic ethanol consumption is a risk factor for colorectal cancer, and ethanol-induced reactive oxygen species have been suggested to play important roles in the pathogenesis of ethanol-related colorectal cancer (ER-CRC). In this study, the effects of 10-week chronic administration of ethanol on the colonic levels of oxidative stress and advance glycation end product (AGE) levels, as well as fecal microbiota structures, were examined in a mouse model. Chronic oral administration of ethanol in mice (1.0 mL of 1.5% or 5.0% ethanol (v/v) per day per mouse, up to 10 weeks) resulted in the elevation of colonic levels of oxidative stress markers (such as 8-hydroxy-2'-deoxyguanosine and 4-hydroxynonenal) compared to control mice, and this was consistently accompanied by elevated levels of inflammation-associated cytokines and immune cells (Th17 and macrophages) and a decreased level of regulatory T (Treg) cells to produce colonic lesions. It also resulted in an alteration of mouse fecal microbiota structures, reminiscent of the alterations observed in human inflammatory bowel disease, and this appeared to be consistent with the proposed sustained generation of oxidative stress in the colonic environment during chronic ethanol consumption. Moreover, the first experimental evidence that chronic ethanol administration results in elevated levels of advanced glycation end products (AGEs) and their receptors (RAGE) in the colonic tissues in mice is also shown, implying enhanced RAGE-mediated signaling with chronic ethanol administration. The RAGE-mediated signaling pathway has thus far been implicated as a link between the accumulation of AGEs and the development of many types of chronic colitis and cancers. Thus, enhancement of this pathway likely exacerbates the ethanol-induced inflammatory states of colonic tissues and might at least partly contribute to the pathogenesis of ER-CRC.

Long-lasting microbial dysbiosis and altered enteric neurotransmitters in adult rats following adolescent binge ethanol exposure

Human alcoholism and ethanol exposure of adult mice cause acute microbial dysbiosis. Adolescent binge drinking is common, but the effect of adolescent ethanol exposure on the adult microbiome and enteric neurotransmitters has not been studied. In the current study, male Wistar rats received adolescent intermittent ethanol (AIE) treatment, and fecal samples were collected on postnatal day (P)54 and P95 for bacterial 16S rRNA amplicon sequencing. Cecal tissue was collected on P95 for analysis of innate immune and neurotransmitter marker expression. At the genus level, AIE treatment altered the relative abundance of several microbes, including decreased relative abundance of Dehalobacterium and CF231 (a member of the Paraprevotellaceae family) that persisted into adulthood. Across aging, the relative abundance of several microbes was altered in both control- and AIE-treated rats. At P95, AIE exposure was associated with increased cecal serotonin levels and reduced choline acetyltransferase gene expression. Taxonomic shifts at P54 and at P95 suggest that AIE causes both immediate and lasting microbial dysbiosis. The lasting microbial dysbiosis was accompanied by alterations of enteric neurotransmitters.

The role of the microbiota in human genetic adaptation

As human populations spread across the world, they adapted genetically to local conditions. So too did the resident microorganism communities that everyone carries with them. However, the collective influence of the diverse and dynamic community of resident microbes on host evolution is poorly understood. The taxonomic composition of the microbiota varies among individuals and displays a range of sometimes redundant functions that modify the physicochemical environment of the host and may alter selection pressures. Here we review known human traits and genes for which the microbiota may have contributed or responded to changes in host diet, climate, or pathogen exposure. Integrating host–microbiota interactions in human adaptation could offer new approaches to improve our understanding of human health and evolution.

Alcohol decreases intestinal ratio of Lactobacillus to Enterobacteriaceae and induces hepatic immune tolerance in a murine model of DSS-colitis

Alcohol can potentiate disease in a mouse model of dextran sodium sulfate (DSS) colitis; however, the underlying mechanism remains to be established. In this study, we assessed whether the potentiated disease could be related to Enterobacteriaceae and Lactobacillus, as changes in their relative abundance can impact intestinal health. We also assessed whether the intestinal barrier is compromised after alcohol and DSS as it may increase bacterial translocation and liver inflammation. Mice were administered DSS followed by binge ethanol or water vehicle, generating four experimental groups: (Control+Vehicle, Control+Ethanol, DSS+Vehicle, DSS+Ethanol). DNA was isolated from colon and cecal contents followed by qPCR for levels of Enterobacteriaceae and Lactobacillus. Colon and liver sections were taken for histology. Intestinal epithelial cells were isolated from the colon for RNA expression. DSS+Ethanol cecal contents exhibited a 1 log increase in Enterobacteriaceae (p < .05), a 0.5 log decrease in Lactobacillus, and a 1.5 log decrease (p < .05) in the Lactobacillus:Enterobacteriaceae ratio compared to DSS+Vehicle, with similar trends in colon contents. These changes correlated with shorter colons and more weight loss. Irrespective of ethanol administration, DSS compromised the mucosal barrier integrity, however only DSS+Ethanol exhibited significant increases in circulating endotoxin. Furthermore, the livers of DSS+Ethanol mice had significantly increased levels of triglycerides, mononuclear cells, yet exhibited significantly depressed expression of liver inflammatory pathways, suggestive of tolerance induction, compared to mice receiving DSS+Vehicle. Our results suggest that ethanol after DSS colitis increases the intestinal burden of Enterobacteriaceae which may contribute to intestinal and liver damage, and the induction of immune tolerance.

Dendropanax morbifera Leaf Extracts Improved Alcohol Liver Injury in Association with Changes in the Gut Microbiota of Rats

This study evaluated the protective effects of Dendropanax morbifera leaf (DML) extracts in the liver due to excessive ethanol consumption. Our results showed that the ethanol extract had better antioxidant activity than the water extract, likely due to the higher levels of total flavonoid and phenolic compounds in the former. We found that the main phenolic acid was chlorogenic acid and the major flavonoid was rutin. Results from the animal model experiment showed concentration-dependent liver protection with the distilled water extract showing better liver protection than the ethanol extract. Gut microbiota dysbiosis induced by alcohol consumption was significantly shifted by DML extracts through increasing mainly Bacteroides and Allobaculum. Moreover, predicted metabolic activities of biosynthesis of beneficial monounsaturated fatty acids such as oleate and palmitoleate were enhanced. Our results suggest that these hepatoprotective effects are likely due to the increased activities of antioxidant enzymes and partially promoted by intestinal microbiota shifts.

Establishing high-accuracy biomarkers for colorectal cancer by comparing fecal microbiomes in patients with healthy families

Colorectal cancer (CRC) causes high morbidity and mortality worldwide, and noninvasive gut microbiome (GM) biomarkers are promising for early CRC diagnosis. However, the GM varies significantly based on ethnicity, diet and living environment, suggesting varied GM biomarker performance in different regions. We performed a metagenomic association analysis on stools from 52 patients and 55 corresponding healthy family members who lived together to identify GM biomarkers for CRC in Chongqing, China. The GM of patients differed significantly from that of healthy controls. A total of 22 microbial genes were included as screening biomarkers with high accuracy in additional 46 cases and 40 randomly selected healthy adults in Chongqing (area under the receive-operation curve (AUC) = 0.905, 95% CI 0.832-0.977). The classifier based on the identified 22 biomarkers also performed well in the cohort from Hong Kong (AUC = 0.811, 95% CI 0.715-0.907) and French (AUC = 0.859, 95% CI 0.773-0.944) populations. Quantitative PCR was applied for measuring three selected biomarkers in the classification of CRC patients in independent Chongqing population containing 30 cases and 30 controls and the best biomarker from Coprobacillus performed well with high AUC (0.930, 95% CI 0.904-0.955). This study revealed increased sensitivity and applicability of our GM biomarkers compared with previous biomarkers significantly promoting the early diagnosis of CRC.

Microbiota and Lifestyle: A Special Focus on Diet

It is widely known that a good balance and healthy function for bacteria groups in the colon are necessary to maintain homeostasis and preserve health. However, the lack of consensus on what defines a healthy gut microbiota and the multitude of factors that influence human gut microbiota composition complicate the development of appropriate dietary recommendations for our gut microbiota. Furthermore, the varied response to the intake of probiotics and prebiotics observed in healthy adults suggests the existence of potential inter- and intra-individual factors, which might account for gut microbiota changes to a greater extent than diet. The changing dietary habits worldwide involving consumption of processed foods containing artificial ingredients, such as sweeteners; the coincident rise in emotional disorders; and the worsening of other lifestyle habits, such as smoking habits, drug consumption, and sleep, can together contribute to gut dysbiosis and health impairment, as well as the development of chronic diseases. This review summarizes the current literature on the effects of specific dietary ingredients (probiotics, prebiotics, alcohol, refined sugars and sweeteners, fats) in the gut microbiota of healthy adults and the potential inter- and intra-individual factors involved, as well as the influence of other potential lifestyle factors that are dramatically increasing nowadays.

Risk of colorectal cancer in patients with alcoholism: A nationwide, population-based nested case-control study

BACKGROUND

Colorectal cancer (CRC) is regarded as a multifactorial disease and shares many risk factors with alcoholism. However, the association between alcoholism and CRC remains controversial.

OBJECTIVES

In this study, we aimed to evaluate the association between alcoholism and risk of CRC.

METHODS

We performed a large-scale, population-based nested case-control study using the Longitudinal Health Insurance Database 2013, derived from Taiwan's National Health Insurance Research Database, and collected data from 2000 to 2013. There were 49,095 diagnosed cases of CRC defined according to the International Classification of Diseases, Ninth Revision, Clinical Modification. Each case was matched with three controls by sex, age, index date of CRC, and annual medical visits; a total of 147,285 controls were identified. Multiple risk factors of CRC in alcoholism cases were investigated using unconditional multiple logistic regression analysis.

RESULTS

Among 49,095 cases of CRC, alcoholism was associated with a significantly higher risk of CRC (adjusted odds ratio (OR), 1.631; 95% CI, 1.565-1.699) in multivariate logistic regression, after adjusting other CRC risk factors, and in stratified analysis with multivariate logistic regression. In addition, there was a time-dependent relationship between alcoholism duration and CRC risk in >1 year, > 2 years, >5 years, and > 11 years groups (adjusted ORs, 1.875, 2.050, 2.662 and 2.670; 95% CI, 1.788-1.967, 1.948-2.158, 2.498-2.835, and 2.511-2.989 respectively).

CONCLUSION

An association between alcoholism and risk of CRC was found in this study. Furthermore, patients with longer alcoholism history showed higher likelihood of developing CRC, which indicates a time-dependent relationship between alcoholism exposure and CRC. Further research on colorectal tumorigenesis is needed.

Colorectal cancer occurrence and treatment based on changes in intestinal flora

Colorectal cancer (CRC) is the most common cancer in the world, and its incidence has been increasing in recent years. The occurrence of CRC is believed to be related to a variety of factors. Epidemiological data indicate that CRC is mainly affected by environmental factors, eating habits, physical activity and genetic factors. As a newly recognized functional component, the intestinal microbiota plays important roles in preventing CRC formation and maintaining intestinal immunity. In this review, we summarize the mechanisms by which the gut microbiota causes CRC through alterations to immune function, focusing on the mechanisms by which intestinal microbial dysfunction promotes CRC. Furthermore, we describe the changes in the intestinal flora observed in CRC and their potential for CRC treatment with the goal of facilitating future research on the roles of the intestinal flora.

Gut microbiota compositional and functional fingerprint in patients with alcohol use disorder and alcohol-associated liver disease

BACKGROUND & AIMS

Alcohol use disorder (AUD) represents the most common cause of liver disease. The gut microbiota plays a critical role in the progression of alcohol-related liver damage. Aim of this study was to characterize the gut microbial composition and function in AUD patients with alcohol-associated liver disease (AALD).

METHODS

This study included 36 AUD patients (14 with cirrhosis) who were active drinkers and an equal number of matched controls. Stool microbial composition, serum levels of lipopolysaccharide, cytokines/chemokines and gut microbiota functional profile were assessed.

RESULTS

AUD patients had a decreased microbial alpha diversity as compared to controls (0.092 vs 0.130, P = .047) and a specific gut microbial signature. The reduction of Akkermansia and the increase in Bacteroides were able to identify AUD patients with an accuracy of 93.4%. Serum levels of lipopolysaccharide (4.91 vs 2.43, P = .009) and pro-inflammatory mediators (tumour necrosis factor alpha 60.85 vs 15.08, P = .001; interleukin [IL] 1beta 4.43 vs 1.72, P = .0001; monocyte chemoattractant protein 1 225.22 vs 16.43, P = .006; IL6 1.87 vs 1.23, P = .008) were significantly increased in AUD patients compared to controls and in cirrhotic patients compared to non-cirrhotic ones (IL6 3.74 vs 1.39, P = .019; IL8 57.60 vs 6.53, P = .004). The AUD-associated gut microbiota showed an increased expression of gamma-aminobutyric acid (GABA) metabolic pathways and energy metabolism.

CONCLUSIONS

AUD patients present a specific gut microbial fingerprint, associated with increased endotoxaemia, systemic inflammatory status and functional alterations that may be involved in the progression of the AALD and in the pathogenesis of AUD.

The Role of the Gut Microbiome in Colorectal Cancer: Where Are We? Where Are We Going?

Microbiome (microbiota) is a community of all microorganisms inhabiting a specific site of the body, including pathogens, which distinguishes it from the physiological microflora. Intestinal dysbiosis plays a key role in the development of colorectal cancer. In the process of carcinogenesis, inflammation, immune response, and toxic metabolites play a significant role. Specific species of bacteria might affect the risk of colorectal cancer and growth of tumor already present. Assessment of changes in the intestinal microbiome during the development and progression of colorectal cancer might create a simple diagnostic tool, a useful biomarker, or might influence treatment strategies in colorectal cancer patients. Analysis of the gut microbiome provides the potential to develop noninvasive diagnostic tests that would be useful as new protective markers of colorectal cancer, prognostic markers in already present colorectal cancer, and predictive markers of response to treatment, especially immunotherapy.

The interplay between dietary factors, gut microbiome and colorectal cancer: a new era of colorectal cancer prevention

Colorectal cancer is the third most common cancer in the world and its incidence is on the rise. Dietary intervention has emerged as an attractive strategy to curtail its occurrence and progression. Diet is known to influence the gut microbiome, as dietary factors and gut bacteria can act in concert to cause or protect from colorectal cancer. Several studies have presented evidence for such interactions and have pointed out the different ways by which the diet and gut microbiome can be altered to produce beneficial effects. This review article aims to summarize the interrelationship between diet, gut flora and colorectal cancer so that a better preventive approach can be applied.

Method for absolute quantification of microbial communities by using both microarrays and competitive PCR

Methods for the robust quantification of bacterial communities are still under development. In this context, the present study aimed to evaluate a method combining competitive PCR (cPCR) and microarray assays for the determination of absolute content of total bacteria and individual bacterial species in samples. For this, a competitor DNA for cPCR and microarrays containing three types of DNA probes was prepared. A calibration curve was generated with genomic DNA samples as standards, which was then utilized for cPCR-based determination of the total number (in moles) of 16S rRNA genes in other bacterial samples. Moreover, scatter plots of species-specific probes versus total bacteria probe for each genomic DNA of known concentration was fit to the regression model, and the obtained slope value was defined as the hybridization affinity ratio. The cPCR assay was performed for both a commercially available mixed genomic DNA sample and human oral bacterial DNA samples, and the total number of moles of 16S rRNA genes was determined. These values were distributed among each species on the basis of the signal intensities of species-specific probes and the hybridization affinity ratio. The total number of bacterial genomes and those of individual species were determined by dividing the copy number of 16S rRNA genes per genome. The obtained results were confirmed by quantitative real-time PCR (qPCR). For values of >1 × 10² copies determined by qPCR, the ratio of the values measured by DNA chips to by qPCR was 1.53-fold on average and <2.6-fold for all data. These results show that the combined method of cPCR and microarray is useful to quantify the absolute numbers of several types of bacteria in a sample at one time.

Adherence to the World Cancer Research Fund/American Institute for Cancer Research 2018 Recommendations for Cancer Prevention and Risk of Colorectal Cancer

BACKGROUND

The World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) 2018 diet, nutrition, and physical activity recommendations aim to reduce cancer risk. We examined adherence to the WCRF/AICR recommendations and colorectal cancer risk in two prospective cohorts.

METHODS

We followed 68,977 women in the Nurses' Health Study and 45,442 men in the Health Professionals Follow-up Study from 1986 until 2012. We created cumulatively averaged WCRF/AICR scores using updated diet, adiposity, and physical activity data from questionnaires, and used Cox regression to estimate sex-specific HRs and 95% confidence intervals (CI) for incident colorectal cancer.

RESULTS

We documented 2,449 colorectal cancer cases. Men in the highest quintile of the WCRF/AICR lifestyle score had a lower risk of colorectal cancer compared with those in the lowest quintile (HRQ5vsQ1 = 0.64; 95% CI, 0.52-0.77). The result was weaker in women (HRQ5vsQ1 = 0.86; 95% CI, 0.72-1.02; P heterogeneity by sex = 0.006). When analyzing the diet recommendations alone, we similarly observed stronger inverse associations in men (HRQ5vsQ1 = 0.74; 95% CI, 0.61-0.90) compared with women (HRQ5vsQ1 = 0.93; 95% CI, 0.77-1.12; P heterogeneity by sex = 0.06). In men, the lifestyle score was more strongly inversely associated with risk of distal colon cancer compared with proximal colon or rectal cancer (P common effects = 0.03); we did not observe significant differences between anatomic locations in women.

CONCLUSIONS

The 2018 WCRF/AICR cancer prevention recommendations are associated with lower colorectal cancer risk in men, with weaker results in women.

IMPACT

Consideration of adiposity and physical activity in conjunction with diet is important for colorectal cancer prevention.