Landscapes and bacterial signatures of mucosa-associated intestinal microbiota in Chilean and Spanish patients with inflammatory bowel disease

A Machine Learning-Based Diagnostic Model for Crohn's Disease and Ulcerative Colitis Utilizing Fecal Microbiome Analysis

Recent research has demonstrated the potential of fecal microbiome analysis using machine learning (ML) in the diagnosis of inflammatory bowel disease (IBD), mainly Crohn's disease (CD) and ulcerative colitis (UC). This study employed the sparse partial least squares discriminant analysis (sPLS-DA) ML technique to develop a robust prediction model for distinguishing among CD, UC, and healthy controls (HCs) based on fecal microbiome data. Using data from multicenter cohorts, we conducted 16S rRNA gene sequencing of fecal samples from patients with CD (n = 671) and UC (n = 114) while forming an HC cohort of 1462 individuals from the Kangbuk Samsung Hospital Healthcare Screening Center. A streamlined pipeline based on HmmUFOTU was used. After a series of filtering steps, 1517 phylotypes and 1846 samples were retained for subsequent analysis. After 100 rounds of downsampling with age, sex, and sample size matching, and division into training and test sets, we constructed two binary prediction models to distinguish between IBD and HC and CD and UC using the training set. The binary prediction models exhibited high accuracy and area under the curve (for differentiating IBD from HC (mean accuracy, 0.950; AUC, 0.992) and CD from UC (mean accuracy, 0.945; AUC, 0.988)), respectively, in the test set. This study underscores the diagnostic potential of an ML model based on sPLS-DA, utilizing fecal microbiome analysis, highlighting its ability to differentiate between IBD and HC and distinguish CD from UC.

Microbiota Phenotype Promotes Anastomotic Leakage in a Model of Rats with Ischemic Colon Resection

Anastomotic leakage (AL) is a major cause of morbidity and mortality after colorectal surgery, but the mechanism behind this complication is still not fully understood. Despite the advances in surgical techniques and perioperative care, the complication rates have remained steady. Recently, it has been suggested that colon microbiota may be involved in the development of complications after colorectal surgery. The aim of this study was to evaluate the association of gut microbiota in the development of colorectal AL and their possible virulence strategies to better understand the phenomenon. Using 16S rRNA sequencing of samples collected on the day of surgery and the sixth day following surgery, we analyzed the changes in tissue-associated microbiota at anastomotic sites created in a model of rats with ischemic colon resection. We discovered a trend for lower microbial diversity in the AL group compared to non-leak anastomosis (NLA). There were no differences in relative abundance in the different types of microbial respiration between these groups and the high abundance of the facultative anaerobic Gemella palaticanis is a marker species that stands out as a distinctive feature.

Enteropathy and gut dysbiosis as obstacles to achieve immune recovery in undetectable people with HIV: a clinical view of evidence, successes, and projections

Immune performance following antiretroviral therapy initiation varies among patients. Despite achieving viral undetectability, a subgroup of patients fails to restore CD4+ T-cell counts during follow-up, which exposes them to non-AIDS defining comorbidities and increased mortality. Unfortunately, its mechanisms are incompletely understood, and no specific treatment is available. In this review, we address some of the pathophysiological aspects of the poor immune response from a translational perspective, with emphasis in the interaction between gut microbiome, intestinal epithelial dysfunction, and immune system, and we also discuss some studies attempting to improve immune performance by intervening in this vicious cycle.

Possible role of nutrition in the prevention of inflammatory bowel disease-related colorectal cancer: A focus on human studies

Patients with inflammatory bowel disease (IBD) are at substantially high risk for colorectal cancer (CRC). IBD-associated CRC accounts for roughly 10% to 15% of the annual mortality in patients with IBD. IBD-related CRC also affects younger patients compared with sporadic CRC, with a 5-y survival rate of 50%. Regardless of medical therapies, the persistent inflammatory state characterizing IBD raises the risk for precancerous changes and CRC, with additional input from several elements, including genetic and environmental risk factors, IBD-associated comorbidities, intestinal barrier dysfunction, and gut microbiota modifications. It is well known that nutritional habits and dietary bioactive compounds can influence IBD-associated inflammation, microbiome abundance and composition, oxidative stress balance, and gut permeability. Additionally, in recent years, results from broad epidemiologic and experimental studies have associated certain foods or nutritional patterns with the risk for colorectal neoplasia. The present study aimed to review the possible role of nutrition in preventing IBD-related CRC, focusing specifically on human studies. It emerges that nutritional interventions based on healthy, nutrient-dense dietary patterns characterized by a high intake of fiber, vegetables, fruit, ω-3 polyunsaturated fatty acids, and a low amount of animal proteins, processed foods, and alcohol, combined with probiotic supplementation have the potential of reducing IBD-activity and preventing the risk of IBD-related CRC through different mechanisms, suggesting that targeted nutritional interventions may represent a novel promising approach for the prevention and management of IBD-associated CRC.

The role of gut microbiome in inflammatory bowel disease diagnosis and prognosis

Inflammatory bowel disease (IBD) is a chronic immune-mediated intestinal disease consisting of ulcerative colitis and Crohn's disease. Inflammatory bowel disease is believed to be developed as a result of interactions between environmental, immune-mediated and microbial factors in a genetically susceptible host. Recent advances in high-throughput sequencing technologies have aided the identification of consistent alterations of the gut microbiome in patients with IBD. Preclinical and murine models have also shed light on the role of beneficial and pathogenic bacteria in IBD. These findings have stimulated interest in development of non-invasive microbial and metabolite biomarkers for predicting disease risk, disease progression, recurrence after surgery and responses to therapeutics. This review briefly summarizes the current evidence on the role of gut microbiome in IBD pathogenesis and mainly discusses the latest literature on the utilization of potential microbial biomarkers in disease diagnosis and prognosis.

The role of cholesterol and mitochondrial bioenergetics in activation of the inflammasome in IBD

Inflammatory Bowel Disease (IBD) is characterized by a loss of intestinal barrier function caused by an aberrant interaction between the immune response and the gut microbiota. In IBD, imbalance in cholesterol homeostasis and mitochondrial bioenergetics have been identified as essential events for activating the inflammasome-mediated response. Mitochondrial alterations, such as reduced respiratory complex activities and reduced production of tricarboxylic acid (TCA) cycle intermediates (e.g., citric acid, fumarate, isocitric acid, malate, pyruvate, and succinate) have been described in in vitro and clinical studies. Under inflammatory conditions, mitochondrial architecture in intestinal epithelial cells is dysmorphic, with cristae destruction and high dynamin-related protein 1 (DRP1)-dependent fission. Likewise, these alterations in mitochondrial morphology and bioenergetics promote metabolic shifts towards glycolysis and down-regulation of antioxidant Nuclear erythroid 2-related factor 2 (Nrf2)/Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) signaling. Although the mechanisms underlying the mitochondrial dysfunction during mucosal inflammation are not fully understood at present, metabolic intermediates and cholesterol may act as signals activating the NLRP3 inflammasome in IBD. Notably, dietary phytochemicals exhibit protective effects against cholesterol imbalance and mitochondrial function alterations to maintain gastrointestinal mucosal renewal in vitro and in vivo conditions. Here, we discuss the role of cholesterol and mitochondrial metabolism in IBD, highlighting the therapeutic potential of dietary phytochemicals, restoring intestinal metabolism and function.

Fusobacterium nucleatum promotes colon cancer progression by changing the mucosal microbiota and colon transcriptome in a mouse model

BACKGROUND

Fusobacterium nucleatum (F. nucleatum) has long been known to cause opportunistic infections and has recently been implicated in colorectal cancer (CRC), which has attracted broad attention. However, the mechanism by which it is involved in CRC development is not fully understood.

AIM

To explore its potential causative role in CRC development, we evaluated the colon pathology, mucosa barrier, colon microbiota and host transcriptome profile after F. nucleatum infection in an azoxymethane/dextran sulfate sodium salt (AOM/DSS) mouse model.

METHODS

Three groups of mice were compared to reveal the differences, i.e., the control, AOM/DSS-induced CRC and AOM/DSS-FUSO infection groups.

RESULTS

Both the AOM/DSS and AOM/DSS-FUSO groups exhibited a significantly reduced body weight and increased tumor numbers than the control group, and AOM/DSS mice with F. nucleatum infection showed the highest tumor formation ratio among the three groups. Moreover, the colon pathology was the most serious in the AOM/DSS-FUSO group. We found that the structure of the colon microbiota changed considerably after F. nucleatum infection; striking differences in mucosal microbial population patterns were observed between the AOM/DSS-FUSO and AOM/DSS groups, and inflammation-inducing bacteria were enriched in the mucosal microbiota in the AOM/DSS-FUSO group. By comparing intestinal transcriptomics data from AOM vs AOM/DSS-FUSO mice, we showed that transcriptional activity was strongly affected by dysbiosis of the gut microbiota. The most microbiota-sensitive genes were oncogenes in the intestine, and the cyclic adenosine monophosphate signaling pathway, neuroactive ligand–receptor interaction, PPAR signaling pathway, retinol metabolism, mineral absorption and drug metabolism were highly enriched in the AOM/DSS-FUSO group. Additionally, we showed that microbial dysbiosis driven by F. nucleatum infection enriched eight taxa belonging to Proteobacteria, which correlates with increased expression of oncogenic genes.

CONCLUSION

Our study demonstrated that F. nucleatum infection altered the colon mucosal microbiota by enriching pathogens related to the development of CRC, providing new insights into the role of F. nucleatum in the oncogenic microbial environment of the colon.

Litter Management Strategies and Their Impact on the Environmental and Respiratory Microbiome Might Influence Health in Poultry

Aerial and respiratory tract-associated bacterial diversity has been scarcely studied in broiler production systems. This study examined the relationship between the environmental air and birds’ respiratory microbiome, considering a longitudinal sampling. Total viable bacteria and coliforms in the air were quantified, and the 16S rRNA gene was sequenced from tracheal and air samples obtained through a novelty protocol. Air results showed a decrease in coliforms over time. However, at week 3, we reported an increase in coliforms (from 143 to 474 CFUc/m3) associated with litter management. Additionally, 16S rRNA gene results indicated a distinctive air microbial community, associated primarily with Bacillota phylum particularly of the Bacilli class (>58%), under all conditions. Tracheal results indicated a predominance of Escherichia coli/Shigella at the beginning of the productive cycle, shifting toward the middle and end of the cycle to Gallibacterium. However, at week 3, the dominance of Escherichia coli/Shigella (>99.5%) associated with litter aeration by tumbling stood out. Tracheal and air samples displayed a statistically different community structure, but shared differentially abundant features through time: Enterococcus, Gallibacterium, and Romboutsia ilealis. These results indicate the impact of production management protocols on the birds’ respiratory system that should be considered a breakpoint in poultry farm health.