Meta-analysis of mucosal microbiota reveals universal microbial signatures and dysbiosis in gastric carcinogenesis

Gastric microbiome signature for predicting metachronous recurrence after endoscopic resection of gastric neoplasm

BACKGROUND

Changes in gastric microbiome are associated with gastric carcinogenesis. Studies on the association between gastric mucosa-associated gastric microbiome (MAM) and metachronous gastric cancer are limited. This study aimed to identify gastric MAM as a predictive factor for metachronous recurrence following endoscopic resection of gastric neoplasms.

METHOD

Microbiome analyses were conducted for 81 patients in a prospective cohort to investigate surrogate markers to predict metachronous recurrence. Gastric MAM in non-cancerous corporal biopsy specimens was evaluated using Illumina MiSeq platform targeting 16S ribosomal DNA.

RESULTS

Over a median follow-up duration of 53.8 months, 16 metachronous gastric neoplasms developed. Baseline gastric MAM varied with Helicobacter pylori infection status, but was unaffected by initial pathologic diagnosis, presence of atrophic gastritis, intestinal metaplasia, or synchronous lesions. The group with metachronous recurrence did not exhibit distinct phylogenetic diversity compared with the group devoid of recurrence but showed significant difference in β-diversity. The study population could be classified into two distinct gastrotypes based on baseline gastric MAM: gastrotype 1, Helicobacter-abundant; gastrotype 2: Akkermansia-abundant. Patients in gastrotype 2 showed higher risk of metachronous recurrence than gastrotype (Cox proportional hazard analysis, adjusted hazard ratio [95% confidence interval]: 5.10 [1.09-23.79]).

CONCLUSIONS

Gastric cancer patients can be classified into two distinct gastrotype groups by their MAM profiles, which were associated with different risk of metachronous recurrence.

Stomach microbiota in gastric cancer development and clinical implications

Gastric cancer (GC) is one of the most common malignancies and a prominent cause of cancer mortality worldwide. A distinctive characteristic of GC is its intimate association with commensal microbial community. Although Helicobacter pylori is widely recognised as an inciting factor of the onset of gastric carcinogenesis, increasing evidence has indicated the substantial involvement of microbes that reside in the gastric mucosa during disease progression. In particular, dysregulation in gastric microbiota could play pivotal roles throughout the whole carcinogenic processes, from the development of precancerous lesions to gastric malignancy. Here, current understanding of the gastric microbiota in GC development is summarised. Potential translational and clinical implications of using gastric microbes for GC diagnosis, prognosis and therapeutics are also evaluated, with further discussion on conceptual haziness and limitations at present. Finally, we highlight that modulating microbes is a novel and promising frontier for the prevention and management of GC, which necessitates future in-depth investigations.

Exploring the Link between Helicobacter pylori, Gastric Microbiota and Gastric Cancer

Gastric cancer (GC) still represents one of the leading causes of cancer-related mortality and is a major public health issue worldwide. Understanding the etiopathogenetic mechanisms behind GC development holds immense potential to revolutionize patients' treatment and prognosis. Within the complex web of genetic predispositions and environmental factors, the connection between Helicobacter pylori (H. pylori) and gastric microbiota emerges as a focus of intense research investigation. According to the most recent hypotheses, H. pylori triggers inflammatory responses and molecular alterations in gastric mucosa, while non-Helicobacter microbiota modulates disease progression. In this review, we analyze the current state of the literature on the relationship between H. pylori and non-Helicobacter gastric microbiota in gastric carcinogenesis, highlighting the mechanisms by which microecological dysbiosis can contribute to the malignant transformation of the mucosa.

Gut microbiome alterations during gastric cancer: evidence assessment of case-control studies

Objectives

The study aims to systematically identify the alterations in gut microbiota that observed in gastric cancer through comprehensive assessment of case-control studies.

Methods

The systematic literature search of PubMed, Embase, Cochrane Library, and Web of Science was conducted to identify case-control studies that compared the microbiomes of individuals with and without gastric cancer. Quality of included studies was evaluated with the Newcastle-Ottawa Quality Assessment Scale (NOS). Meta-analyses utilized a random-effects model, and subgroup and sensitivity analyses were performed to assess study heterogeneity. All data analyses were performed using the "metan" package in Stata 17.0, and the results were described using log odds ratios (log ORs) with 95% confidence intervals (CIs).

Results

A total of 33 studies involving 4,829 participants were eligible for analysis with 29 studies provided changes in α diversity and 18 studies reported β diversity. Meta-analysis showed that only the Shannon index demonstrated statistical significance for α-diversity [-5.078 (-9.470, -0.686)]. No significant differences were observed at the phylum level, while 11 bacteria at genus-level were identified significant changed, e.g., increasing in Lactobacillus [5.474, (0.949, 9.999)] and Streptococcus [5.095, (0.293, 9.897)] and decreasing in Porphyromonas and Rothia with the same [-8.602, (-11.396, -5.808)]. Sensitivity analysis indicated that the changes of 9 bacterial genus were robust. Subgroup analyses on countries revealed an increasing abundance of Helicobacter and Streptococcus in Koreans with gastric cancer, whereas those with gastric cancer from Portugal had a reduced Neisseria. Regarding the sample sources, the study observed an increase in Lactobacillus and Bacteroides in the gastric mucosa of people with gastric cancer, alongside Helicobacter and Streptococcus. However, the relative abundance of Bacteroides decreased compared to the non-gastric cancer group, which was indicated in fecal samples.

Conclusion

This study identified robust changes of 9 bacterial genus in people with gastric cancer, which were country-/sample source-specific. Large-scale studies are needed to explore the mechanisms underlying these changes.

Systematic Review

Unique Identifier: CRD42023437426 https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023437426.

Effect of bile reflux on gastric juice microbiota in patients with different histology phenotypes

BACKGROUND/AIMS

Bile reflux (BR) can influence the gastric environment by altering gastric acidity and possibly the gastric microbiota composition. This study investigated the correlation between bile acids and microbial compositions in the gastric juice of 50 subjects with differing gastric pathologies.

METHODS

This study included 50 subjects, which were categorized into three groups based on the endoscopic BR grading system. The primary and secondary bile acid concentrations in gastric juice samples were measured, and microbiota profiling was conducted using 16 S rRNA gene sequencing.

RESULTS

Significant differences were observed in each bile acid level in the three endoscopic BR groups (P < 0.05). The Shannon index demonstrated a significant decrease in the higher BR groups (P < 0.05). Analysis of the β-diversity revealed that BR significantly altered the gastric microbiota composition. The presence of neoplastic lesions and the presence of H. pylori infection impacted the β-diversity of the gastric juice microbiota. The abundance of the Streptococcus and Lancefielfdella genera exhibited positive correlations for almost all bile acid components(P < 0.05). In addition, the abundance of Slobacterium, Veillonella, and Schaalia showed positive correlations with primary unconjugated bile acids (P < 0.05).

CONCLUSION

Changes in microbial diversity in the gastric juice were associated with BR presence in the stomach. This result suggests that the degree of BR should be considered when studying the gastric juice microbiome.

Global status and trends of gastric cancer and gastric microbiota research: a bibliometric analysis

Background

Numerous studies have cast light on the relationship between the gastric microbiota and gastric carcinogenesis. In this study, we conducted a bibliometric analysis of the relevant literature in the field of gastric cancer and the gastric microbiota and clarified its research status, hotspots, and development trends.

Materials and methods

Publications were retrieved from the Web of Science Core Collection on 18 July 2023. CiteSpace 6.2.R4, VOSviewer 1.6.19.0, and Biblioshiny were used for the co-occurrence and cooperation analyses of countries, institutions, authors, references, and keywords. A keyword cluster analysis and an emergence analysis were performed, and relevant knowledge maps were drawn.

Results

The number of published papers in this field totaled 215 and showed an increasing trend. The analysis of funding suggested that the input in this field is increasing steadily. China had the highest number of publications, while the United States had the highest betweenness centrality. Baylor College of Medicine published the most articles cumulatively. Both Ferreira RM and Cooker OO had the highest citation frequency. The journal Helicobacter showed the most interest in this field, while Gut provided a substantial research foundation. A total of 280 keywords were obtained using CiteSpace, which were primarily focused on the eradication and pathogenic mechanisms of Helicobacter pylori, as well as the application of the gastric microbiota in the evaluation and treatment of gastric cancer. The burst analysis suggested that in the future, research may focus on the application of gastric microorganisms, particularly Fusobacterium nucleatum, in the diagnosis and treatment of gastric cancer, along with their pathogenic mechanisms.

Conclusion

Current studies have been tracking the eradication of Helicobacter pylori and its pathogenic mechanisms, as well as changes in the gastric microbiota during gastric carcinogenesis. Future research may focus on the clinical application and pathogenesis of stomach microorganisms through bacteria such as Fusobacterium nucleatum.

Intestinal Dysbiosis: Microbial Imbalance Impacts on Colorectal Cancer Initiation, Progression and Disease Mitigation

The human gastrointestinal tract houses a diverse range of microbial species that play an integral part in many biological functions. Several preclinical studies using germ-free mice models have demonstrated that the gut microbiome profoundly influences carcinogenesis and progression. Colorectal cancer appears to be associated with microbial dysbiosis involving certain bacterial species, including F. nucleatum, pks+ E. coli, and B. fragilis, with virome commensals also disrupted in patients. A dysbiosis toward these pro-carcinogenic species increases significantly in CRC patients, with reduced numbers of the preventative species Clostridium butyicum, Roseburia, and Bifidobacterium evident. There is also a correlation between Clostridium infection and CRC. F. nucleatum, in particular, is strongly associated with CRC where it is associated with therapeutic resistance and poor outcomes in patients. The carcinogenic mode of action of pathogenic bacteria in CRC is a result of genotoxicity, epigenetic alterations, ROS generation, and pro-inflammatory activity. The aim of this review is to discuss the microbial species and their impact on colorectal cancer in terms of disease initiation, progression, and metastasis. The potential of anticancer peptides as anticancer agents or adjuvants is also discussed, as novel treatment options are required to combat the high levels of resistance to current pharmaceutical options.

Promising dawn in tumor microenvironment therapy: engineering oral bacteria

Despite decades of research, cancer continues to be a major global health concern. The human mouth appears to be a multiplicity of local environments communicating with other organs and causing diseases via microbes. Nowadays, the role of oral microbes in the development and progression of cancer has received increasing scrutiny. At the same time, bioengineering technology and nanotechnology is growing rapidly, in which the physiological activities of natural bacteria are modified to improve the therapeutic efficiency of cancers. These engineered bacteria were transformed to achieve directed genetic reprogramming, selective functional reorganization and precise control. In contrast to endotoxins produced by typical genetically modified bacteria, oral flora exhibits favorable biosafety characteristics. To outline the current cognitions upon oral microbes, engineered microbes and human cancers, related literatures were searched and reviewed based on the PubMed database. We focused on a number of oral microbes and related mechanisms associated with the tumor microenvironment, which involve in cancer occurrence and development. Whether engineering oral bacteria can be a possible application of cancer therapy is worth consideration. A deeper understanding of the relationship between engineered oral bacteria and cancer therapy may enhance our knowledge of tumor pathogenesis thus providing new insights and strategies for cancer prevention and treatment.

Uncovering Microbial Composition of the Tissue Microenvironment in Bladder Cancer using RNA Sequencing Data

Purpose: Bladder cancer (BC) is one of the top 10 common tumors in the world. It has been reported that microbiota can colonize tissues and play important roles in tumorigenesis and progression. However, the current understanding of microorganisms in the BC tissue microenvironment remains unclear. Methods: In this study, we integrated the RNA-seq data of 479 BC tissue samples from seven datasets combined with a range of bioinformatics tools to explore the landscape of microbiome in the BC tissue microenvironment. Results: The pan-microbiome was estimated to surpass 1,400 genera. A total of seven core microbiota (Bacillus, Corynebacterium, Cutibacterium, Escherichia, Halomonas, Pasteurella, and Streptomyces) were identified. Among them, Bacillus was widely distributed in all datasets with a high relative abundance (10.11% of all samples on average). Moreover, some biological factors, including tissue source and tumor grade, were found significant effects on the microbial composition of the bladder tissue. Pseudomonas, Porphyrobacter, and Acinetobacter were enriched in tumor tissues, while Mycolicibacterium and Streptomyces were enriched in patients who showed durable response to BCG therapy. In addition, we established microbial co-occurrence networks and found that the BCG therapy may attenuate the microbiological interactions. Conclusions: This study clearly provided a microbial landscape of the BC tissue microenvironment, which was important for exploring the interactions between microorganisms and BC tissues. The identified specific taxa might be potential biomarkers for BC.

The role of microbiota in gastric cancer: A comprehensive review

BACKGROUND

Gastric cancer (GC) continues to pose a significant global threat in terms of cancer-related fatalities. Despite notable advancements in medical research and therapies, further investigation is warranted to elucidate its underlying etiology and risk factors. Recent times have witnessed an escalated emphasis on comprehending the role of the microbiota in cancer development.

METHODS

This review briefly delves into recent developments in microbiome-related research pertaining to gastric cancer.

RESULTS

According to studies, the microbiota can influence GC growth by inciting inflammation, disrupting immunological processes, and generating harmful microbial metabolites. Furthermore, there is ongoing research into how the microbiome can impact a patient's response to chemotherapy and immunotherapy.

CONCLUSION

The utilization of the microbiome for detecting, preventing, and managing stomach cancer remains an active area of exploration.

Cancer invasion and anaerobic bacteria: new insights into mechanisms

There is growing evidence that altered microbiota abundance of a range of specific anaerobic bacteria are associated with cancer, including Peptoniphilus spp., Porphyromonas spp., Fusobacterium spp., Fenollaria spp., Prevotella spp., Sneathia spp., Veillonella spp. and Anaerococcus spp. linked to multiple cancer types. In this review we explore these pathogenic associations. The mechanisms by which bacteria are known or predicted to interact with human cells are reviewed and we present an overview of the interlinked mechanisms and hypotheses of how multiple intracellular anaerobic bacterial pathogens may act together to cause host cell and tissue microenvironment changes associated with carcinogenesis and cancer cell invasion. These include combined effects on changes in cell signalling, DNA damage, cellular metabolism and immune evasion. Strategies for early detection and eradication of anaerobic cancer-associated bacterial pathogens that may prevent cancer progression are proposed.

RE.GA.IN.: the Real-world Gastritis Initiative-updating the updates

At the end of the last century, a far-sighted 'working party' held in Sydney, Australia addressed the clinicopathological issues related to gastric inflammatory diseases. A few years later, an international conference held in Houston, Texas, USA critically updated the seminal Sydney classification. In line with these initiatives, Kyoto Global Consensus Report, flanked by the Maastricht-Florence conferences, added new clinical evidence to the gastritis clinicopathological puzzle.The most relevant topics related to the gastric inflammatory diseases have been addressed by the Real-world Gastritis Initiative (RE.GA.IN.), from disease definitions to the clinical diagnosis and prognosis. This paper reports the conclusions of the RE.GA.IN. consensus process, which culminated in Venice in November 2022 after more than 8 months of intense global scientific deliberations. A forum of gastritis scholars from five continents participated in the multidisciplinary RE.GA.IN. consensus. After lively debates on the most controversial aspects of the gastritis spectrum, the RE.GA.IN. Faculty amalgamated complementary knowledge to distil patient-centred, evidence-based statements to assist health professionals in their real-world clinical practice. The sections of this report focus on: the epidemiology of gastritis; Helicobacter pylori as dominant aetiology of environmental gastritis and as the most important determinant of the gastric oncogenetic field; the evolving knowledge on gastric autoimmunity; the clinicopathological relevance of gastric microbiota; the new diagnostic horizons of endoscopy; and the clinical priority of histologically reporting gastritis in terms of staging. The ultimate goal of RE.GA.IN. was and remains the promotion of further improvement in the clinical management of patients with gastritis.

Gastric microbiota in patients with gastric MALT lymphoma according to Helicobacter pylori infection

BACKGROUND

Gastric Mucosa Associated Lymphoid Tissue lymphoma (GML) development is triggered by Helicobacter pylori (H. pylori) infection. Little is known about the impact of H. pylori infection on gastric microbiota.

METHODS

The gastric microbiota was retrospectively investigated using 16S rRNA gene sequencing in 32 patients with untreated GML (10 H. pylori-positive and 22 H. pylori-negative), 23 with remitted and 18 refractory GML and 35 controls. Differences in microbial diversity, bacterial composition and taxonomic repartition were assessed.

RESULTS

There was no change in diversity and bacterial composition between GML and control patients taking into account H. pylori status. Differential taxa analysis identified specific changes associated with H. pylori-negative GML: the abundances of Actinobacillus, Lactobacillus and Chryseobacterium were increased while the abundances of Veillonella, Atopobium, Leptotrichia, Catonella, Filifactor and Escherichia_Shigella were increased in control patients. In patients with remitted GML, the genera Haemophilus and Moraxella were significantly more abundant than in refractory patients, while Atopobium and Actinomyces were significantly more abundant in refractory patients.

CONCLUSION

Detailed analysis of the gastric microbiota revealed significant changes in the bacterial composition of the gastric mucosa in patients with GML that may have a role in gastric lymphomagenesis but not any new pathobionts.

Comparison of Helicobacter pylori positive and negative gastric cancer via multi-omics analysis

IMPORTANCE

This is the first clinical research to systematically expound the difference between gastric cancer (GC) individuals with Helicobacter pylori and GC individuals without H. pylori from the perspective of multi-omics. This clinical study identified significant genes, microbes, and fecal metabolites, which exhibited nice power for differentiating GC individuals with H. pylori infection from GC individuals without H. pylori infection. This study provides a crucial basis for a better understanding of eradication therapy among the GC population.

TCM syndrome differentiation in colorectal cancer patients assisted by differences in gut microbiota: An exploratory study

Objective

To explore the difference in gut microbiota between different traditional Chinese Medicine (TCM) syndromes in patients with colorectal cancer (CRC) and its internal relationship.

Methods

From June 2020 to August 2021, 109 colorectal cancer patients with a clear pathological diagnosis who had not yet undergone surgery or chemotherapy were classified according to the TCM syndrome classification, and the feces samples of 109 patients with preoperative colorectal cancer were collected. 16s rRNA gene sequencing was used to determine gut microbiota diversity and abundance in CRC patients with different TCM syndrome, and LEfSe analysis was made to screen different TCM syndrome for differential representative microbiota.

Results

109 patients were divided into 5 syndromes by TCM syndrome classification, which were Liver and Kidney Yin Deficiency Syndrome (LKYDS, n = 19), Spleen Deficient Qi Stagnation Syndrome (SDQSS, n = 30), Stasis and Poison Obstruction Syndrome (SPOS, n = 17), Damp-Heat Syndrome (DHS, n = 30), Qi and Blood Deficiency Syndrome (QBDS, n = 13). Alpha diversity index showed significant differences among the five groups of TCM syndromes, with Shannon index being highest in the SDQSS group and lowest in the LKYDS (p = 0.003). ACE index being highest in the SDQSS group and lowest in the SPOS (p = 0.010). PD whole tree index being highest in the SDQSS group and lowest in the SPOS (p = 0.017). Similarly, beta diversity showed significant differences among the five groups of TCM syndromes, with principal coordinate analysis (PCo1 = 31.86 %, PCo2 = 5.62 %) showing separation and coincidence between the groups, and Adonis group differences showing coincidence between the QBDS-LKYDS (p = 0.702), QBDS-DHS (p = 0.133), and SDQSS-DHS (p = 0.260) groups. LEfSe analysis revealed that the representative microbiota of DHS patients was Dialister sp Marseille P5638 (LDA = 3.05, p＜0.001), the representative microbiota of SPOS patients was Oscillospirales (LDA = 4.78, p = 0.029), the representative microbiota of SDQSS patients was Selenomonadaceae (LDA = 3.94, p = 0.003), the representative microbiota of LKYDS patients was Dialister (LDA = 4.19, p = 0.001), and the representative microbiota of QBDS patients was Akkermansia muciniphila (LDA = 4.23, p = 0.006).

Conclusions

There are significant differences in gut microbiota between different TCM syndromes in CRC patients. The five microbiota, Dialister sp Marseille P5638, Oscillospirales, Selenomonadaceae, Dialister, and Akkermansia muciniphila, may be differential markers of TCM syndrome in CRC and are expected to be one of the bases for accurate TCM syndrome differentiation of CRC.

Therapeutic Approach Targeting Gut Microbiome in Gastrointestinal Infectious Diseases

While emerging evidence highlights the significance of gut microbiome in gastrointestinal infectious diseases, treatments like Fecal Microbiota Transplantation (FMT) and probiotics are gaining popularity, especially for diarrhea patients. However, the specific role of the gut microbiome in different gastrointestinal infectious diseases remains uncertain. There is no consensus on whether gut modulation therapy is universally effective for all such infections. In this comprehensive review, we examine recent developments of the gut microbiome's involvement in several gastrointestinal infectious diseases, including infection of Helicobacter pylori, Clostridium difficile, Vibrio cholerae, enteric viruses, Salmonella enterica serovar Typhimurium, Pseudomonas aeruginosa Staphylococcus aureus, Candida albicans, and Giardia duodenalis. We have also incorporated information about fungi and engineered bacteria in gastrointestinal infectious diseases, aiming for a more comprehensive overview of the role of the gut microbiome. This review will provide insights into the pathogenic mechanisms of the gut microbiome while exploring the microbiome's potential in the prevention, diagnosis, prediction, and treatment of gastrointestinal infections.

Helicobacter pylori-associated Chronic Atrophic Gastritis and Progression of Gastric Carcinogenesis

Chronic inflammation due to a Helicobacter pylori (H. pylori) infection is a representative cause of gastric cancer that can promote gastric carcinogenesis by abnormally activating immune cells and increasing the inflammatory cytokines levels. H. pylori infections directly cause DNA double-strand breaks in gastric epithelial cells and genetic damage by increasing the enzymatic activity of cytidine deaminase. Eventually, gastric cancer is induced through dysplasia. Hypermethylation of tumor suppressor genes is an important cause of gastric cancer because of a H. pylori infection. In addition, the changes in gastric microbiota and the mucosal inflammatory changes associated with a co-infection with the Epstein-Barr virus are associated with gastric cancer development. DNA damage induced by H. pylori and the subsequent responses of gastric stem cells have implications for gastric carcinogenesis. Although the pathogenesis of H. pylori has been established, many uncertainties remain, requiring more study.

Synergistic Strategies for Gastrointestinal Cancer Care: Unveiling the Benefits of Immunonutrition and Microbiota Modulation

Gastrointestinal (GI) cancers are a group of highly prevalent malignant tumors affecting the gastrointestinal tract. Globally, one in four cancer cases and one in three cancer deaths are estimated to be GI cancers. They can alter digestive and absorption functions, leading to severe malnutrition which may worsen the prognosis of the patients. Therefore, nutritional intervention and monitoring play a fundamental role in managing metabolic alterations and cancer symptoms, as well as minimizing side effects and increasing the effectiveness of chemotherapy. In this scenario, the use of immunonutrients that are able to modulate the immune system and the modification/regulation of the gut microbiota composition have gained attention as a possible strategy to improve the conditions of these patients. The complex interaction between nutrients and microbiota might contribute to maintaining the homeostasis of each individual's immune system; therefore, concurrent use of specific nutrients in combination with traditional cancer treatments may synergistically improve the overall care of GI cancer patients. This work aims to review and discuss the role of immunonutrition and microbiota modulation in improving nutritional status, postoperative recovery, and response to therapies in patients with GI cancer.

Microbiomes, Their Function, and Cancer: How Metatranscriptomics Can Close the Knowledge Gap

The interaction between the microbial communities in the human body and the onset and progression of cancer has not been investigated until recently. The vast majority of the metagenomics research in this area has concentrated on the composition of microbiomes, attempting to link the overabundance or depletion of certain microorganisms to cancer proliferation, metastatic behaviour, and its resistance to therapies. However, studies elucidating the functional implications of the microbiome activity in cancer patients are still scarce; in particular, there is an overwhelming lack of studies assessing such implications directly, through analysis of the transcriptome of the bacterial community. This review summarises the contributions of metagenomics and metatranscriptomics to the knowledge of the microbial environment associated with several cancers; most importantly, it highlights all the advantages that metatranscriptomics has over metagenomics and suggests how such an approach can be leveraged to advance the knowledge of the cancer bacterial environment.

The Influence of the Microbiome on Immunotherapy for Gastroesophageal Cancer

Immunotherapy has shown promise as a treatment option for gastroesophageal cancer, but its effectiveness is limited in many patients due to the immunosuppressive tumor microenvironment (TME) commonly found in gastrointestinal tumors. This paper explores the impact of the microbiome on the TME and immunotherapy outcomes in gastroesophageal cancer. The microbiome, comprising microorganisms within the gastrointestinal tract, as well as within malignant tissue, plays a crucial role in modulating immune responses and tumor development. Dysbiosis and reduced microbial diversity are associated with poor response rates and treatment resistance, while specific microbial profiles correlate with improved outcomes. Understanding the complex interactions between the microbiome, tumor biology, and immunotherapy is crucial for developing targeted interventions. Microbiome-based biomarkers may enable personalized treatment approaches and prediction of patient response. Interventions targeting the microbiome, such as microbiota-based therapeutics and dietary modifications, offer the potential for reshaping the gut microbiota and creating a favorable TME that enhances immunotherapy efficacy. Further research is needed to reveal the underlying mechanisms, and large-scale clinical trials will be required to validate the efficacy of microbiome-targeted interventions.

The role of fungi in the diagnosis of colorectal cancer

Colorectal cancer (CRC) is a prevalent tumour with high morbidity rates worldwide, and its incidence among younger populations is rising. Early diagnosis of CRC can help control the associated mortality. Fungi are common microorganisms in nature. Recent studies have shown that fungi may have a similar association with tumours as bacteria do. As an increasing number of tumour-associated fungi are discovered, this provides new ideas for the diagnosis and prognosis of tumours. The relationship between fungi and colorectal tumours has also been recently identified by scientists. Therefore, this paper describes the limitations and prospects of the application of fungi in diagnosing CRC and predicting CRC prognosis.

Reduced DEFA5 Expression and STAT3 Activation Underlie the Submucosal Invasion of Early Gastric Cancers

INTRODUCTION

Submucosal invasion is a core hallmark of early gastric cancer (EGC) with poor prognosis. However, the molecular mechanism of the progression from intramucosal gastric cancer (IMGC) to early submucosal-invasive gastric cancer (SMGC) is not fully understood. The objective of this study was to identify genes and pathways involved in the submucosal invasion in EGC using comprehensive gene expression analysis.

METHODS

Gene expression profiling was performed for eight cases of IMGC and eight cases of early SMGC with submucosal invasion ≥500 μm. To validate the findings of gene expression analysis and to examine the gene expression pattern in tissues, immunohistochemical (IHC) staining was performed for 50 cases of IMGC and SMGC each.

RESULTS

Gene expression analysis demonstrated that the expression levels of small intestine-specific genes were significantly decreased in SMGC. Among them, defensin alpha 5 (DEFA5) was the most downregulated gene in SMGC, which was further validated in SMGC tissues by IHC staining. Gene set enrichment analysis showed a strong association between SMGC, the JAK-STAT signaling pathway, and the upregulation of STAT3-activating cytokines. The expression of phosphorylated STAT3 was significant in the nucleus of tumor cells in SMGC tissues but not in areas expressing DEFA5.

CONCLUSION

The results of this study strongly suggest that the downregulation of DEFA5 and the activation of STAT3 play a significant role in the submucosal invasion of EGC.

Association between Gut Microbiota and Digestive System Cancers: A Bidirectional Two-Sample Mendelian Randomization Study

Accumulating evidence indicates that gut microbiota closely correlates with the tumorigenesis of digestive system cancers (DSCs). However, whether the causality between gut microbiota and DSCs exists is unknown. Genome-wide association study (GWAS) summary statistics for gut microbiota and DSCs and the bidirectional two-sample Mendelian randomization (MR) analysis were utilized to assess the causality between gut microbiota and DSCs. Sensitivity analyses were performed to evaluate the robustness of our results. We found that the genus Eggerthella (OR = 0.464, 95%CI: 0.27 to 0.796, p = 0.005) was negatively associated with the risk of gastric cancer. The genetically predicted genus Lachnospiraceae FCS020 group (OR = 0.607, 95%CI: 0.439 to 0.84, p = 0.003) correlated with a lower risk of colorectal cancer, and genus Turicibacter (OR = 0.271, 95%CI: 0.109 to 0.676, p = 0.005) was a protective factor for liver cancer. In the reverse MR, DSCs regulated the relative abundance of specific strains of gut microbiota. We comprehensively screened the association between gut microbiota and DSCs using a bidirectional two-sample MR analysis and identified the causality between several microbial taxa and DSCs. Our discoveries are beneficial for the development of novel microbial markers and microbiota-modifying therapeutics for DSC patients.

The gut dysbiosis-cancer axis: illuminating novel insights and implications for clinical practice

The human intestinal microbiota, also known as the gut microbiota, comprises more than 100 trillion organisms, mainly bacteria. This number exceeds the host body cells by a factor of ten. The gastrointestinal tract, which houses 60%-80% of the host's immune cells, is one of the largest immune organs. It maintains systemic immune homeostasis in the face of constant bacterial challenges. The gut microbiota has evolved with the host, and its symbiotic state with the host's gut epithelium is a testament to this co-evolution. However, certain microbial subpopulations may expand during pathological interventions, disrupting the delicate species-level microbial equilibrium and triggering inflammation and tumorigenesis. This review highlights the impact of gut microbiota dysbiosis on the development and progression of certain types of cancers and discusses the potential for developing new therapeutic strategies against cancer by manipulating the gut microbiota. By interacting with the host microbiota, we may be able to enhance the effectiveness of anticancer therapies and open new avenues for improving patient outcomes.

Linking dysbiosis to precancerous stomach through inflammation: Deeper than and beyond imaging

Upper gastrointestinal endoscopy is considered the gold standard for gastric lesions detection and surveillance, but it is still associated with a non-negligible rate of missing conditions. In the Era of Personalized Medicine, biomarkers could be the key to overcome missed lesions or to better predict recurrence, pushing the frontier of endoscopy to functional endoscopy. In the last decade, microbiota in gastric cancer has been extensively explored, with gastric carcinogenesis being associated with progressive dysbiosis. Helicobacter pylori infection has been considered the main causative agent of gastritis due to its interference in disrupting the acidic environment of the stomach through inflammatory mediators. Thus, does inflammation bridge the gap between gastric dysbiosis and the gastric carcinogenesis cascade and could the microbiota-inflammation axis-derived biomarkers be the answer to the unmet challenge of functional upper endoscopy? To address this question, in this review, the available evidence on the role of gastric dysbiosis and chronic inflammation in precancerous conditions of the stomach is summarized, particularly targeting the nuclear factor-κB (NF-κB), toll-like receptors (TLRs) and cyclooxygenase-2 (COX-2) pathways. Additionally, the potential of liquid biopsies as a non-invasive source and the clinical utility of studied biomarkers is also explored. Overall, and although most studies offer a mechanistic perspective linking a strong proinflammatory Th1 cell response associated with, but not limited to, chronic infection with Helicobacter pylori, promising data recently published highlights not only the diagnostic value of microbial biomarkers but also the potential of gastric juice as a liquid biopsy pushing forward the concept of functional endoscopy and personalized care in gastric cancer early diagnosis and surveillance.

Dynamic variations of the gastric microbiota: Key therapeutic points in the reversal of Correa's cascade

Correa's cascade is a dynamic process in the development of intestinal-type gastric cancer (GC), and its pathological features, gastric microbiota and interactions between microorganisms and their hosts vary at different developmental stages. The characteristics of cells, tissues and gastric microbiota before or after key therapeutic points are critical for monitoring malignant transformation and early tumour reversal. This review summarises the pathological features of gastric mucosa, characteristics of gastric microbiota, specific microbial markers, microbe-microbe interactions and microbe-host interactions at different stages in Correa's cascade. The markers related to each Correa's cascade point were analysed in detail. We attempted to identify key therapeutic points for early cancer reversal and provide a novel approach to reduce the incidence of GC and improve precise treatment.

Gastric microbiota in gastric cancer: Different roles of Helicobacter pylori and other microbes

Gastric cancer (GC) is one of the leading causes of cancer-related deaths worldwide. The gastric microbiota plays a critical role in the development of GC. First, Helicobacter pylori (H. pylori) infection is considered a major risk factor for GC. However, recent studies based on microbiota sequencing technology have found that non-H. pylori microbes also exert effects on gastric carcinogenesis. Following the infection of H. pylori, gastric microbiota dysbiosis could be observed; the stomach is dominated by H. pylori and the abundances of non-H. pylori microbes reduce substantially. Additionally, decreased microbial diversity, alterations in the microbial community structure, negative interactions between H. pylori and other microbes, etc. occur, as well. With the progression of gastric lesions, the number of H. pylori decreases and the number of non-H. pylori microbes increases correspondingly. Notably, H. pylori and non-H. pylori microbes show different roles in different stages of gastric carcinogenesis. In the present mini-review, we provide an overview of the recent findings regarding the role of the gastric microbiota, including the H. pylori and non-H. pylori microbes, in the development of GC.

Clinical Pathogenesis, Molecular Mechanisms of Gastric Cancer Development

The human pathogen Helicobacter pylori is the strongest known risk factor for gastric disease and cancer, and gastric cancer remains a leading cause of cancer-related death across the globe. Carcinogenic mechanisms associated with H. pylori are multifactorial and are driven by bacterial virulence constituents, host immune responses, environmental factors such as iron and salt, and the microbiota. Infection with strains that harbor the cytotoxin-associated genes (cag) pathogenicity island, which encodes a type IV secretion system (T4SS) confer increased risk for developing more severe gastric diseases. Other important H. pylori virulence factors that augment disease progression include vacuolating cytotoxin A (VacA), specifically type s1m1 vacA alleles, serine protease HtrA, and the outer-membrane adhesins HopQ, BabA, SabA and OipA. Additional risk factors for gastric cancer include dietary factors such as diets that are high in salt or low in iron, H. pylori-induced perturbations of the gastric microbiome, host genetic polymorphisms, and infection with Epstein-Barr virus. This chapter discusses in detail host factors and how H. pylori virulence factors augment the risk of developing gastric cancer in human patients as well as how the Mongolian gerbil model has been used to define mechanisms of H. pylori-induced inflammation and cancer.

Gastric Cancer: The Microbiome Beyond Helicobacter pylori

Gastric cancer remains an important global health burden. Helicobacter pylori is the major etiological factor in gastric cancer, infecting the stomach of almost half of the population worldwide. Recent progress in microbiome research offered a new perspective on the complexity of the microbial communities of the stomach. Still, the role of the microbiome of the stomach beyond H. pylori in gastric carcinogenesis is not well understood and requires deeper investigation. The gastric bacterial communities of gastric cancer patients are distinct from those of patients without cancer, but the microbial alterations that occur along the process of gastric carcinogenesis, and the mechanisms through which microorganisms influence cancer progression still need to be clarified. Except for Epstein-Barr virus, the potential significance of the virome and of the mycobiome in gastric cancer have received less attention. This chapter updates the current knowledge regarding the gastric microbiome, including bacteria, viruses, and fungi, within the context of H. pylori-mediated carcinogenesis. It also reviews the possible roles of the local gastric microbiota, as well as the microbial communities of the oral and gut ecosystems, as biomarkers for gastric cancer detection. Finally, it discusses future perspectives and acknowledges limitations in the area of microbiome research in the gastric cancer setting, to which further research efforts should be directed. These will be fundamental not only to increase our current understanding of host-microbial interactions but also to facilitate translation of the findings into innovative preventive, diagnostic, and therapeutic strategies to decrease the global burden of gastric cancer.

Depletion of butyrate-producing microbes of the Firmicutes predicts nonresponse to FMT therapy in patients with recurrent Clostridium difficile infection

Approximately 10% of individuals diagnosed with Clostridium difficile infection (CDI) show the resistance to fecal microbiota transplantation (FMT), with the underlying mechanisms remaining elusive. Deciphering the intricate microbiome profile within this particular subset of FMT-refractory patients via clinical FMT investigations assumes paramount importance, as it holds the key to designing targeted therapeutic interventions tailored for CDI, particularly recurrent CDI (rCDI). A cohort of twenty-three patients afflicted with rCDI, exhibiting congruent clinical baselines, was meticulously selected for FMT. Rigorous screening of thousands of healthy individuals identified ten FMT donors who met stringent health standards, while a total of 171 stool samples were collected to serve as healthy controls. To assess the influence of microbiome dynamics on FMT efficacy, fecal samples were collected from four donors over a continuous period of twenty-five weeks. After FMT treatment, seven individuals exhibited an inadequate response to FMT. These non-remission patients displayed a significant reduction in α-diversity indexes. Meanwhile, prior to FMT, the abundance of key butyrate-producing Firmicutes bacteria, including Christensenellaceae_R_7_group, Ruminococcaceae_unclassified, Coprococcus_2, Fusicatenibacter, Oscillospira, and Roseburia, were depleted in non-remission patients. Moreover, Burkholderiales_unclassified, Coprococcus_2, and Oscillospira failed to colonize non-remission patients both pre- and post-treatment. Conversely, patients with a favorable FMT response exhibited a higher relative abundance of Veillonella prior to treatment, whereas its depletion was commonly observed in non-remission individuals. Genera interactions in lower effectiveness FMT donors were more similar to those in non-remission patients, and Burkholderiales_unclassified, Coprococcus_2, and Oscillospira were frequently depleted in these lower effectiveness donors. Older patients were not conducive to the colonization of Veillonella, consistent with their poor prognosis after FMT. FMT non-remission rCDI patients exhibited distinct characteristics that hindered the colonization of beneficial butyrate-producing Firmicutes microbes. These findings hold promise in advancing the precision of FMT therapy for rCDI patients.

Influence of Helicobacter pylori oncoprotein CagA in gastric cancer: A critical-reflective analysis

Gastric cancer is the fifth most common malignancy and third leading cancer-related cause of death worldwide. Helicobacter pylori is a Gram-negative bacterium that inhabits the gastric environment of 60.3% of the world’s population and represents the main risk factor for the onset of gastric neoplasms. CagA is the most important virulence factor in H. pylori, and is a translocated oncoprotein that induces morphofunctional modifications in gastric epithelial cells and a chronic inflammatory response that increases the risk of developing precancerous lesions. Upon translocation and tyrosine phosphorylation, CagA moves to the cell membrane and acts as a pathological scaffold protein that simultaneously interacts with multiple intracellular signaling pathways, thereby disrupting cell proliferation, differentiation and apoptosis. All these alterations in cell biology increase the risk of damaged cells acquiring pro-oncogenic genetic changes. In this sense, once gastric cancer sets in, its perpetuation is independent of the presence of the oncoprotein, characterizing a “hit-and-run” carcinogenic mechanism. Therefore, this review aims to describe H. pylori- and CagA-related oncogenic mechanisms, to update readers and discuss the novelties and perspectives in this field.