The microbiota: a crucial mediator in gut homeostasis and colonization resistance

The gastrointestinal mycobiome in inflammation and cancer: unraveling fungal dysbiosis, pathogenesis, and therapeutic potential

The gastrointestinal mycobiome, comprising diverse fungal species, plays a significant role in gastrointestinal carcinogenesis and inflammatory bowel disease (IBD) pathogenesis. Recent studies have demonstrated that dysbiosis of the gut mycobiome, characterized by an overrepresentation of pathogenic fungi such as Candida albicans and Aspergillus, correlates with increased inflammation and cancer risk. For instance, C. albicans has been shown to induce colonic inflammation through the activation of pattern recognition receptors and the release of pro-inflammatory cytokines, exacerbating IBD symptoms and potentially facilitating tumorigenesis. Additionally, metagenomic analyses have revealed distinct fungal signatures in colorectal cancer tissues compared to adjacent healthy tissues, highlighting the potential of fungi as biomarkers for disease progression. Mechanistically, gut fungi contribute to disease through biofilm formation, mycotoxin secretion (e.g., aflatoxins, candidalysin), pro-inflammatory cytokine induction (e.g., IL-1β, IL-17), and disruption of epithelial barriers-creating a tumor-promoting and inflammation-prone environment. Furthermore, the interplay between fungi and the bacterial microbiome can amplify inflammatory responses, contributing to chronic inflammation and cancer development. Fungal interactions with bacterial communities also play a synergistic role in shaping mucosal immune responses and enhancing disease severity in both cancer and IBD contexts. As research continues to elucidate these complex fungal-host and fungal-bacterial interactions, targeting the gut mycobiome may offer novel therapeutic avenues for managing IBD and gastrointestinal cancers, emphasizing the need for integrated, mechanistically informed approaches to microbiome research.

Akkermansia muciniphila Protects Against Trinitrobenzene Sulfonic Acid Induced Colitis by Inhibiting IL6/STAT3 Pathway

BACKGROUND

Inflammatory bowel disease is a long-standing inflammatory disorder that influences the intestinal tract. The intent of this research is to explore whether the relative abundance of Akkermansia muciniphila is related to the IL6/STAT3 pathway and the fundamental molecular mechanisms of A. muciniphila on a trinitrobenzene sulfonic acid (TNBS)-induced enteritis mouse model, including the expression of inflammatory cytokines and proteins in the IL6/STAT3 signaling pathway.

METHODS

The association between the A. muciniphila and IL6/STAT3 was investigated by using mucosal biopsies and fecal samples. TNBS-induced colitis mouse models were performed to elucidate the underlying mechanisms. The alteration of intestinal microbiota was organized by 16s rRNA sequencing.

RESULTS

In Crohn's disease patients, the level of STAT3 and IL-6 presented a negative relationship with A. muciniphila. The expression of IL-6, p-STAT3, and STAT3 was downregulated in A.m+TNBS group, indicating A. muciniphila may inhibit the IL6/STAT3 pathway in TNBS-induced enteritis in vivo. To investigate the potential defensive role of A. muciniphila supplementation in vivo with TNBS-induced enteritis, 16S rRNA sequencing was performed to analyze changes in the intestinal microbiota composition. The results revealed a marked increase in microbial diversity and abundance within the A. muciniphila-treated group, suggesting a beneficial modulation of the gut microbiome associated with the supplementation.

CONCLUSIONS

Our findings declared that A. muciniphila supplementation alleviates gastrointestinal inflammation through IL-6/STAT3 signaling pathway. This protective effect was mediated by the downregulation of the IL-6 and STAT3, highlighting a potential mechanism by which A. muciniphila modulates inflammatory responses. This work disclosed that A. muciniphila demonstrates a defensive influence against TNBS-induced enteritis in vivo, proposing it qualified as a unique therapeutic focusing on modulating IL-6, STAT3, or p-STAT3 in the treatment of colitis.

Evaluation of extended-spectrum β-lactamase producing bacteria in feces of shelter dogs as a biomarker for altered gut microbial taxa and functional profiles

Background

The USA is home to 83-88 million dogs, with 3-7 million living in shelters. Shelter dogs move through the supply chain from their geographical origin to adoptive homes, with possible exposure to pathogens and shift in their gut microbiota. However, research in this area is limited. This study examined the effects of intestinal colonization by ESBL bacteria on gut taxa abundance, diversity, and functions in 52 shelter dogs of various ages, sexes, and fertility statuses.

Methodology

We isolated fecal DNA, sequenced their 16S, processed the sequences using DADA2, identified taxa profiles in each dog by Phyloseq, and analyzed Chao1, Shannon, and Simpson alpha diversity by ggplot2 and Wilcoxon test. We analyzed beta diversity using Bray-Curtis dissimilarity matrix from the vegan package. Differential abundance of taxa, gut microbiome functions, and differential abundance of microbiome functions were analyzed using DESeq2, PICRUSt2, and ALDEx2, respectively, with Wilcoxon rank and Kruskal-Wallis tests for comparisons between dog groups.

Results

Firmicutes (69.3%), Bacteroidota (13.5%), Actinobacteriota (6.77%), Proteobacteria (5.54%), and Fusobacteriota (4.75%) were the major phyla in the gut of shelter dogs. ESBL bacteria colonized dogs had reduced gut microbiota alpha diversity than non-colonized dogs. The abundance levels of the following phyla (Proteobacteria, Deferribacterota, Bacteroidota, Fusobacteriota, and Spirochaetota), class (Gammaproteobacteria, Bacteroidia, Deferribacteres, Brachyspirae, and Fusobacteria), and families (Enterobacteriaceae, Peptostreptococcaceae, Lactobacillaceae, Lachnospiraceae, Prevotellaceae, and Peptostreptococcaceae) were significantly (p < 0.05) varied between the two dog groups. Further stratified analysis by age, sex, and spaying/neutering status influenced the abundance of taxa in ESBL bacteria colonized dogs, indicating these covariates act as effect modifiers. Most gut metabolic and biosynthetic pathways were downregulated in ESBL bacteria colonized dogs compared to non-colonized dogs. However, alpha-linolenic acid metabolism and shigellosis, fluorobenzoate degradation, allantoin degradation, toluene degradation, glycol degradation, fatty acid and beta-oxidation, and glyoxylate metabolism bypass pathways were increased in dogs colonized by ESBL bacteria.

Conclusion

Colonization by ESBL bacteria marks altered gut microbiota. Dog's demography and fertility status modify the alterations, indicating host factors and ESBL bacteria interplay to shape gut microbiota. ESBL bacteria or other factors reprogram gut microbiome functions through down and upregulating multiple metabolic and biosynthesis pathways to promote ESBL bacteria colonization.

TLR5's Role in Obesity-related Hypertension: Updated Evidence and Prospects

Toll-like receptor 5 (TLR5), integral to the immune system as a primary sensor for flagellin, is central to the link between innate and adaptive immunity, modulating immune responses and cytokine production essential for defense against flagellated pathogens and immune tolerance. This review consolidates the understanding of TLR5's structural and signaling mechanisms and its interactions with flagellin, shedding light on its dual role in immune responses and its promise as a therapeutic target. It highlights TLR5's intricate role in the pathogenesis of obesity-related hypertension, a growing global health concern that correlates with rising obesity rates and is characterized by a complex interplay of immune responses and metabolic dysregulation. Despite the current understanding, the impact of TLR5 on obesity-related hypertension is marked by conflicting findings, indicating a need for further exploration. The review critically analyzes the existing literature, providing novel insights from rodent models and human studies that underscore TLR5's therapeutic potential, setting the stage for transformative research in managing obesity-related hypertension. It calls for deeper investigation into TLR5's multifaceted role, emphasizing its promise as a target for managing obesity-related hypertension and the necessity for future research to clarify its complexities and to innovate treatment strategies.

Behavioral and multiomics analysis of 3D clinostat simulated microgravity effect in mice focusing on the central nervous system

A study was conducted to evaluate the three-dimensional clinostat simulated microgravity effect on mouse models, focusing on the central nervous system. Eighteen mice were divided into three groups: control, survival box, and clinostat + survival box. Behavioral tests, femur micro-CT, brain transcriptomics, serum metabolomics, and fecal microbiomics were performed. Results showed decreased activity, altered gait, enhanced fear memory, bone loss, immune/endocrine changes in brain transcriptome, and altered metabolic pathways in serum and gut microbiota in clinostat-treated mice. The model closely mimics spaceflight-induced transcriptome changes, suggesting its value in studying microgravity-related neurological alterations and highlighting the need for attention to emotional changes in space.

Plasma Epstein-Barr Virus DNA load for diagnostic and prognostic assessment in intestinal Epstein-Barr Virus infection

Background

The prospective application of plasma Epstein-Barr virus (EBV) DNA load as a noninvasive measure of intestinal EBV infection remains unexplored. This study aims to identify ideal threshold levels for plasma EBV DNA loads in the diagnosis and outcome prediction of intestinal EBV infection, particularly in cases of primary intestinal lymphoproliferative diseases and inflammatory bowel disease (IBD).

Methods

Receiver operating characteristic (ROC) curves were examined to determine suitable thresholds for plasma EBV DNA load in diagnosing intestinal EBV infection and predicting its prognosis.

Results

108 patients were retrospectively assigned to the test group, while 56 patients were included in the validation group. Plasma EBV DNA loads were significantly higher in the intestinal EBV infection group compared to the non-intestinal EBV infection group (Median: 2.02 × 102 copies/mL, interquartile range [IQR]: 5.49 × 101-6.34×103 copies/mL versus 4.2×101 copies/mL, IQR: 1.07 ×101-6.08×101 copies/mL; P < 0.0001). Plasma EBV DNA levels at 9.21×101 and 6.77×101 copies/mL proved beneficial for the identification and prognostication in intestinal EBV infection, respectively. Values of 0.82 and 0.71 were yielded by the area under the ROC curve (AUC) in the test cohort, corresponding to sensitivities of 84.38% (95% confidence interval [95%CI]: 68.25%-93.14%) and 87.5% (95%CI: 69%-95.66%), specificities of 83.33% (95%CI: 64.15%-93.32%) and 68.09% (95%CI: 53.83%-79.6%), positive predictive values (PPV) of 87.1% (95%CI: 71.15%-94.87%) and 58.33% (95%CI: 42.2%-72.86%), and positive likelihood ratios (LR+) of 5.06 and 2.74 in the validation cohort, respectively. Furthermore, a plasma EBV DNA load of 5.4×102 copies/mL helped differentiate IBD with intestinal EBV infection from primary intestinal EBV-positive lymphoproliferative disorders (PIEBV+LPDs), achieving an AUC of 0.85 within the test cohort, as well as 85% sensitivity (95%CI: 63.96%-94.76%), 91.67% specificity (95%CI: 64.61%-99.57%), 94.44% PPV (95%CI: 74.24%-99.72%), and an LR+ of 10.2 in the validation cohort.

Conclusions

Plasma EBV DNA load demonstrates notable potential in distinguishing between different patient cohorts with intestinal EBV infection, although its sensitivity requires further optimization for clinical application.

Insights into the Relationship Between the Gut Microbiome and Immune Checkpoint Inhibitors in Solid Tumors

Immunotherapy with immune checkpoint inhibitors represents a revolutionary approach to the treatment of solid tumors, including malignant melanoma, lung cancer, and gastrointestinal malignancies. Anti-CTLA-4 and anti-PD-1/PDL-1 therapies provide prolonged survival for cancer patients, but their efficacy and safety are highly variable. This review focuses on the crucial role of the gut microbiome in modulating the efficacy and toxicity of immune checkpoint blockade. Studies suggest that the composition of the gut microbiome may influence the response to immunotherapy, with specific bacterial strains able to promote an anti-tumor immune response. On the other hand, dysbiosis may increase the risk of adverse effects, such as immune-mediated colitis. Interventions aimed at modulating the microbiome, including the use of probiotics, prebiotics, fecal microbial transplantation, or dietary modifications, represent promising strategies to increase treatment efficacy and reduce toxicity. The combination of immunotherapy with the microbiome-based strategy opens up new possibilities for personalized treatment. In addition, factors such as physical activity and nutritional supplementation may indirectly influence the gut ecosystem and consequently improve treatment outcomes in refractory patients, leading to enhanced patient responses and prolonged survival.

Immunomodulation of exopolysaccharide produced by Lacticaseibacillus rhamnosus ZFM216 in cyclophosphamide-induced immunosuppressed mice by modulating gut microbiota

This study investigated the immunoregulatory activity of exopolysaccharides (EPS) produced by Lacticaseibacillus rhamnosus ZFM216 in immunosuppressed mice induced by cyclophosphamide (CTX). The results showed that EPS treatment effectively improved the body weight, immune organ index and splenic lymphocyte proliferation. EPS also mitigated the damage of immune organs, restored intestinal morphology, and regulated the levels of serum hemolysin and cytokines (e.g. TNF-α, INF-γ and IL-10). EPS promoted the release of NO, TNF-α, IL-1β, and IL-6 in RAW 264.7 cells, however, such effect was inhibited in the presence of inhibitors of TLR4 and MAPKs signaling pathways-related proteins, confirming that EPS achieved the immunomodulation by activating these two signaling pathways. Additionally, EPS, as a prebiotic, effectively improved the diversity of microbial communities, regulated the relative abundance of dominant microbial communities, restored CTX-induced gut microbiota dysbiosis, and promoted the production of short chain fatty acids (SCFAs) in the gut of mice. Thus, immunoregulatory effect of EPS could be attributed to its good ability to modulate the gut microbiota. EPS produced by L. rhamnosus ZFM216 has promising application as an ingredient of functional foods due to its potent probiotic effect.

Modulatory effects of traditional Chinese medicines on gut microbiota and the microbiota-gut-x axis

The gut microbiota offers numerous benefits to the human body, including the promotion of nutrient absorption, participation in metabolic processes, and enhancement of immune function. Recent studies have introduced the concept of the gut-organ axis, which encompasses interactions such as the gut-brain axis, gut-liver axis, and gut-lung axis. This concept underscores the complex interplay between gut microbiota and various organs and tissues, including the brain, heart, lungs, liver, kidneys, muscles, and bones. Growing evidence indicates that gut microbiota can influence the onset and progression of multi-organ system diseases through their effects on the gut-organ axis. Traditional Chinese medicine has demonstrated significant efficacy in regulating the gastrointestinal system, leveraging its unique advantages. Considerable advancements have been made in understanding the role of gut microbiota and the gut-organ axis within the mechanisms of action of traditional Chinese medicine. This review aims to elucidate the roles of gut microbiota and the gut-organ axis in human health, explore the potential connections between traditional Chinese medicine and gut microbiota, and examine the therapeutic effects of traditional Chinese medicine on the microbiota-gut-organ axis. Furthermore, the review addresses the limitations and challenges present in current research while proposing potential directions for future investigations in this area.