The role of the gut microbiota in gastric cancer: the immunoregulation and immunotherapy

Investigating the role of inflammatory cytokines in mediating the effect of gut microbiota on gastrointestinal cancers: a mendelian randomization study

PURPOSE

The purpose of this study is to explore the causal relationship between gut microbiota and gastrointestinal (GI) cancers and to investigate the potential mediating factors influencing the development of GI cancers.

METHODS

Using data from genome-wide association studies (GWAS), we employed two-sample Mendelian randomization (TSMR) to explore the relationship among gut microbiota, inflammatory cytokines and GI cancers. Subsequently, a multivariable Mendelian randomization (MVMR) analysis was meticulously conducted to perform a mediation analysis, thereby estimating the proportion of mediation effects conferred by inflammatory cytokines.

RESULTS

TSMR analysis established a causal relationship between 23 gut microbiota taxa and 11 inflammatory cytokines with GI cancers. Specifically, 7 gut microbiota taxa were associated with an increased risk of gastric cancer (GC), 6 with small intestine cancer, and 10 with colorectal cancer (CRC). Among the inflammatory cytokines, 4 were linked to GC risk, 3 to small intestine cancer, and to CRC. Mediation analysis further indicatedthat tumor necrosis factor ligand superfamily member 12 (TNFSF12) mediated 9.703% (95% CI 0.108%~15.891%) of the total effect of genus Ruminiclostridium9 on GC.

CONCLUSION

Our findings support a causal relationship between gut microbiota, inflammatory cytokines, and GI cancers. These biomarkers provide new insights into the mechanisms underlying GI cancers and have the potential to improve strategies forprevention, diagnosis, and treatment.

Relationship between Helicobacter pylori infection and programmed death-ligand 1 in gastric cancer: A meta-analysis

BACKGROUND

Gastric cancer (GC) is one of the most common malignancies worldwide, and Helicobacter pylori (HP) infection is a well-established risk factor for its development. Programmed death-ligand 1 (PD-L1) expression is a crucial biomarker for predicting the efficacy of immune checkpoint inhibitors in cancer treatment. While HP infection and PD-L1 expression in GC may be linked, the relationship between them remains unclear, in part because there have been conflicting results reported from various studies.

AIM

To perform a meta-analysis to assess the relationship between HP and PD-L1 expression in patients with GC.

METHODS

A systematic literature review was conducted using PubMed, Embase, Cochrane Library, and Web of Science databases. Observational studies that examined the association between HP infection and PD-L1 expression in patients with GC were included. Odds ratios and 95% confidence intervals were calculated to estimate the association. Heterogeneity was assessed using Cochrane’s Q test and I² statistic. A random-effects model was used due to significant heterogeneity across studies.

RESULTS

Fourteen studies involving a total of 3069 patients with GC were included. The pooled analysis showed a significant association between HP infection and increased PD-L1 expression in GC tissues (odd ratio = 1.69, 95% confidence interval: 1.24-2.29, P < 0.001, I² = 59%). Sensitivity analyses confirmed the robustness of these findings. Subgroup analyses did not show significant variation based on geographic region, sample size, or method of PD-L1 assessment. Publication bias was minimal, as shown by funnel plots and Egger’s regression test.

CONCLUSION

HP infection is associated with increased PD-L1 expression in GC, suggesting that HP status may influence the response to programmed cell death protein 1/PD-L1 blockade therapy.

Gut microbiota affects PD-L1 therapy and its mechanism in melanoma

Immune checkpoint inhibitors (ICIs), particularly PD-1/PD-L1 blockade, have shown great success in treating melanoma. PD-L1 (B7-H1, CD274), a ligand of PD-1, binds to PD-1 on T cells, inhibiting their activation and proliferation through multiple pathways, thus dampening tumor-reactive T cell activity. Studies have linked PD-L1 expression in melanoma with tumor growth, invasion, and metastasis, making the PD-1/PD-L1 pathway a critical target in melanoma therapy. However, immune-related adverse events are common, reducing the effectiveness of anti-PD-L1 treatments. Recent evidence suggests that the gut microbiome significantly influences anti-tumor immunity, with the microbiome potentially reprogramming the tumor microenvironment and overcoming resistance to anti-PD-1 therapies in melanoma patients. This review explores the mechanisms of PD-1/PD-L1 in melanoma and examines how gut microbiota and its metabolites may help address resistance to anti-PD-1 therapy, offering new insights for improving melanoma treatment strategies.

Gut microbiota therapy in gastrointestinal diseases

The human gut microbiota, consisting of trillions of microorganisms, plays a crucial role in gastrointestinal (GI) health and disease. Dysbiosis, an imbalance in microbial composition, has been linked to a range of GI disorders, including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), celiac disease, and colorectal cancer. These conditions are influenced by the interactions between the gut microbiota, the host immune system, and the gut-brain axis. Recent research has highlighted the potential for microbiome-based therapeutic strategies, such as probiotics, prebiotics, fecal microbiota transplantation (FMT), and dietary modifications, to restore microbial balance and alleviate disease symptoms. This review examines the role of gut microbiota in the pathogenesis of common gastrointestinal diseases and explores emerging therapeutic approaches aimed at modulating the microbiome. We discuss the scientific foundations of these interventions, their clinical effectiveness, and the challenges in their implementation. The review underscores the therapeutic potential of microbiome-targeted treatments as a novel approach to managing GI disorders, offering personalized and alternative options to conventional therapies. As research in this field continues to evolve, microbiome-based interventions hold promise for improving the treatment and prevention of gastrointestinal diseases.

Gut Microbiota-Tumor Microenvironment Interactions: Mechanisms and Clinical Implications for Immune Checkpoint Inhibitor Efficacy in Cancer

Cancer immunotherapy has transformed cancer treatment in recent years, with immune checkpoint inhibitors (ICIs) emerging as a key therapeutic approach. ICIs work by inhibiting the mechanisms that allow tumors to evade immune detection. Although ICIs have shown promising results, especially in solid tumors, patient responses vary widely due to multiple intrinsic and extrinsic factors within the tumor microenvironment. Emerging evidence suggests that the gut microbiota plays a pivotal role in modulating immune responses at the tumor site and may even influence treatment outcomes in cancer patients receiving ICIs. This review explores the complex interactions between the gut microbiota and the tumor microenvironment, examining how these interactions could impact the effectiveness of ICI therapy. Furthermore, we discuss how dysbiosis, an imbalance in gut microbiota composition, may contribute to resistance to ICIs, and highlight microbiota-targeted strategies to potentially overcome this challenge. Additionally, we review recent studies investigating the diagnostic potential of microbiota profiles in cancer patients, considering how microbial markers might aid in early detection and stratification of patient responses to ICIs. By integrating insights from recent preclinical and clinical studies, we aim to shed light on the potential of microbiome modulation as an adjunct to cancer immunotherapy and as a diagnostic tool, paving the way for personalized therapeutic approaches that optimize patient outcomes.

Exploring the mediating role of blood metabolites in the relationship between gut microbiota and gastric cancer risk: a Mendelian randomization study

Background

Prior studies have established correlations between gut microbiota (GM) dysbiosis, circulating metabolite alterations, and gastric cancer (GC) risk. However, the causal nature of these associations remains uncertain.

Methods

We utilized summary data from genome-wide association studies (GWAS) on GM (European, n=8,956), blood metabolites (European, n=120,241; East Asian, n=4,435), and GC (European, n=476,116; East Asian, n=167,122) to perform a bidirectional Mendelian randomization (MR) analysis, investigating the causal effects of GM and metabolites on GC risk. Additionally, we conducted mediation analysis (two-step MR) to identify potential metabolite mediators in the GM-GC relationship.

Results

We identified twelve negative and seven positive associations between specific GM taxa and GC risk. For blood metabolites, seven traits were found to be significantly associated with reduced GC risk in the European population, with these findings subsequently validated in the East Asian cohort. Three GM taxa showed potential causal associations with five metabolic traits: the Bacteroidia class and Bacteroidales order were positively correlated with five metabolites (all P < 0.013), while Bacteroides OTU97_27 exhibited a negative correlation with one metabolite (P = 0.007). Two-step MR analysis indicated that total lipids in intermediate-density lipoprotein (IDL), IDL particle concentration, phospholipids in medium low-density lipoprotein (LDL), phospholipids in small LDL, and free cholesterol in small LDL indirectly influenced the association between Bacteroidia class/Bacteroidales order and GC, with mediation proportions of 1.71% (P = 0.048), 1.69% (P = 0.048), 2.05% (P = 0.045), 1.85% (P = 0.048), and 1.99% (P = 0.045), respectively.

Conclusion

The present study provides suggestive evidence of a causal relationship between specific GM, blood metabolites, and GC risk, potentially offering new insights into GC etiology.

The role of MAPK pathway in gastric cancer: unveiling molecular crosstalk and therapeutic prospects

Gastric cancer remains a significant health burden globally, especially prevalent in Asian and European regions. Despite a notable decline in incidence in the United States and Western Europe over recent decades, the disease's persistence underscores the urgency for advanced research in its pathogenesis and treatment strategies. Central to this pursuit is the exploration of the mitogen-activated protein kinase (MAPK) pathway, a pivotal cellular mechanism implicated in the complex processes of gastric cancer development, including cellular proliferation, invasion, migration, and metastasis. The MAPK or extracellular signal-regulated kinase pathway serves as a crucial conduit for transmitting extracellular signals to elicit intracellular responses, with its signaling cascades subject to alterations due to genetic and epigenetic variations across various diseases, prominently cancer. This review delves into the intricate role of the MAPK signaling pathway in the pathogenesis of gastric cancer, drawing upon the most recent and critical studies that shed light on MAPK pathway alterations as a gateway to the disease. It highlights the pathway's involvement in Helicobacter pylori-mediated gastric carcinogenesis and the tumorigenic processes induced by the Epstein-Barr virus, showcasing the substantial influence of miRNAs and lncRNAs in modulating gastric cancer's biological properties through their interaction with the MAPK pathway. Furthermore, the review extends into the therapeutic arena, discussing the promising impacts of herbal medicines, MAPK pathway inhibitors, and immunosuppressants on mitigating gastric cancer's progression. Through an exhaustive examination of the MAPK pathway's multifaceted role in gastric cancer, from molecular crosstalks to therapeutic prospects, this review aspires to contribute to the ongoing efforts in understanding and combating this global health challenge, paving the way for novel therapeutic interventions and improved patient outcomes.

Microbiota and Cytokine Modulation: Innovations in Enhancing Anticancer Immunity and Personalized Cancer Therapies

The gut microbiota plays a crucial role in modulating anticancer immunity, significantly impacting the effectiveness of various cancer therapies, including immunotherapy, chemotherapy, and radiotherapy. Its impact on the development of cancer is complex; certain bacteria, like Fusobacterium nucleatum and Bacteroides fragilis, can stimulate the growth of tumors by causing immunological evasion and inflammation, while advantageous strains, like Faecalibaculum rodentium, have the ability to suppress tumors by modifying immune responses. Cytokine activity and immune system regulation are intimately related. Cytokines including TGF-β, IL-6, and IL-10 promote tumor development by inhibiting efficient immune surveillance. The gut microbiome exhibits a delicate balance between pro- and anti-tumorigenic factors, as evidenced by the enhancement of anti-tumor immunity by cytokines such as IL-12 and IFN-γ. Improved immunotherapy responses are linked to a diverse microbiota, which is correlated with higher tumor infiltration and cytotoxic T-cell activation. Because microbial metabolites, especially short-chain fatty acids, affect cytokine expression and immune cell activation inside the tumor microenvironment, this link highlights the need to maintain microbial balance for optimal treatment effects. Additionally, through stimulating T-cell activation, bacteria like Lactobacillus rhamnosus and Bifidobacterium bifidum increase cytokine production and improve the efficacy of immune checkpoint inhibitors (ICIs). An option for overcoming ICI resistance is fecal microbiota transplantation (FMT), since research suggests that it improves melanoma outcomes by increasing CD8+ T-cell activation. This complex interaction provides an opportunity for novel cancer therapies by highlighting the possibility of microbiome modification as a therapeutic approach in personalized oncology approaches.

Identification of FGG as a Biomarker in Early Gastric Cancer via Tissue Proteomics and Clinical Verification

Early and accurate diagnosis of gastric cancer (GC) is essential for reducing mortality and improving patient well-being. However, methods for the early diagnosis of GC are still lacking. In this study, by isobaric tagging for relative and absolute quantitation (iTRAQ), we identified 336 proteins that overlapped among the upregulated differentially expressed proteins (DEPs) in early gastric cancer (EGC) versus progressive gastric cancer (PGC), upregulated DEPs in EGC versus nongastric cancer (NGC), and nonsignificant proteins in EGC versus NGC. These DEPs were involved primarily in the neutrophil-related immune response. Network analysis of proteins and pathways revealed that fibrinogen α (FGA), β (FGB), and γ (FGG) are candidates for distinguishing EGC. Furthermore, parallel reaction monitoring (PRM), immunohistochemistry (IHC), and Western blot (WB) assays of clinical samples confirmed that, compared with that in PGC and NGC, only FGG was uniquely and significantly upregulated in the gastric mucosa of EGC. Our results demonstrated that FGG in the gastric mucosa could be a novel biomarker to diagnose EGC patients via endoscopy.

Impact the impact of gut microbiota on gastric cancer via immune cells: a comprehensive Mendelian randomization study and mediation analysis

PURPOSE

Recent observational studies have highlighted the role of altered gut microbiota (GM) in the activation of the host immune system and the resulting of gastric cancer (GC). However, the exact causal relationship and mechanisms of action are still not fully understood.

MATERIALS AND METHODS

Genetic data from published genome-wide association studies (GWASs) were employed to determine the causal effects of 207 taxa and 205 bacterial pathways on GC via two-sample Mendelian randomization (MR) and two-step mediation MR analysis. In this study, 731 immune cell traits served as potential mediators. An inverse variance-weighted (IVW) estimation, augmented by a range of alternative estimators, notably the Bayesian-weighted MR method, was employed as the primary methodological approach.

RESULTS

Four taxa and five bacterial pathways were found to be negatively correlated with GC, whereas one taxon and two bacterial pathways were a positively correlated with GC. Reverse causality was not found in the reverse MR analysis. Additional validation was performed using a sensitivity analysis. Mediation MR analyses revealed that the GM influences GC through various phenotypes of 16 immune cells that act as mediators. For example, s_Alistipes_sp_AP11 was found to inhibit GC through NKT %T cell (total effect: -0.3234, mediation effect: 0.0212). This mediating effect further highlights the complex relationship among GMs, immune cell traits, and their combined effects on GC.

CONCLUSIONS

Our findings highlight the genetic connection between specific GMs and GC, emphasizing the potential role of immune cells as mediators, and offering valuable perspectives on potential therapeutic strategies that manipulating the GM to address GC.

Cannabinoids and triple-negative breast cancer treatment

Triple-negative breast cancer (TNBC) accounts for about 10-20% of all breast cancer cases and is associated with an unfavorable prognosis. Until recently, treatment options for TNBC were limited to chemotherapy. A new successful systemic treatment is immunotherapy with immune checkpoint inhibitors, but new tumor-specific biomarkers are needed to improve patient outcomes. Cannabinoids show antitumor activity in most preclinical studies in TNBC models and do not appear to have adverse effects on chemotherapy. Clinical data are needed to evaluate efficacy and safety in humans. Importantly, the endocannabinoid system is linked to the immune system and immunosuppression. Therefore, cannabinoid receptors could be a potential biomarker for immune checkpoint inhibitor therapy or a novel mechanism to reverse resistance to immunotherapy. In this article, we provide an overview of the currently available information on how cannabinoids may influence standard therapy in TNBC.

The Impact of Tobacco Smoking and Alcohol Consumption on the Development of Gastric Cancers

Chronic infection of Helicobacter pylori is considered the principal cause of gastric cancers, but evidence has accumulated regarding the impact of tobacco smoking and alcohol consumption on the development of gastric cancers. Several possible mechanisms, including the activation of nicotinic acetylcholine receptors, have been proposed for smoking-induced gastric carcinogenesis. On the other hand, local acetaldehyde exposure and ethanol-induced mucosal inflammation have been proposed as the mechanisms involved in the development of gastric cancers in heavy alcohol drinkers. In addition, genetic polymorphisms are also considered to play a pivotal role in smoking-related and alcohol-related gastric carcinogenesis. In this review, we will discuss the molecular mechanisms involved in the development of gastric cancers in relation to tobacco smoking and alcohol consumption.

Aspirin eugenol ester affects ileal barrier function, inflammatory response and microbiota in broilers under lipopolysaccharide-induced immune stress conditions

Aims

The aim of this study was to investigate the effects of aspirin eugenol ester (AEE) on ileal immune function in broilers under lipopolysaccharide (LPS)-induced immune stress.

Methods

Two hundred and forty one-day-old male Arbor Acres chicks were randomly divided into four groups (saline, LPS, saline + AEE and LPS + AEE) with six replicates of ten broilers each. The saline group and LPS group were fed the normal diet, while the other two groups received normal diet plus 0.1 g/kg AEE. Broilers in the LPS and LPS + AEE groups were injected intraperitoneally with 0.5 mg/kg B.W LPS in saline for seven consecutive days beginning at 14 days of age, while broilers in the saline and saline + AEE groups were injected with saline only.

Results

The results showed that AEE improved the ileal morphology and increased the ratio of villus height to crypt depth of immune-stressed broilers. LPS-induced immune stress significantly reduced the expression of the genes for the tight junction proteins occludin, zonula occludens-1 (ZO-1), claudin-1 and claudin-2, in the ileum, while AEE significantly up-regulated the expression of these genes. Compared with the saline group, the LPS-treated chickens showed significantly increased mRNA expression of the inflammatory factors tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), cyclooxygenase-2 (COX-2), and microsomal Prostaglandin E Synthesase-1 (mPGES-1) in the ileum, while they were significantly decreased by AEE supplementation. In addition, analysis of the ileal bacterial composition showed that compared with saline and LPS + AEE groups, the proportion of Firmicutes and Lactobacillus in the LPS group was lower, while the proportion of Proteobacteria and Escherichia-Shigella was higher. Similarly, Line Discriminant Analysis Effect Size (LEfSe) analysis showed that compared with the LPS group, Brevibacillus was dominant in the saline group, while the LPS + AEE group was rich in Rhizobium, Lachnoclostridium, Ruminococcaceae, Faecalibacterium, Negativibacillus, Oscillospiraceae, and Flavonifractor.

Conclusion

These results indicate that dietary supplementation with 0.1 g/kg AEE could protect the intestinal health by improving the intestinal villus morphology, enhancing the expression of tight junction genes and alleviating inflammation to resist the immune stress caused by LPS stimulation in broilers, and the mechanism may involve COX-2-related signal transduction and improved intestinal microbiota composition.

Association between gut microbiota and gastric cancers: a two-sample Mendelian randomization study

Background

Gastric cancer (GC) is the fifth most commonly diagnosed cancer worldwide, with its etiology attributed to a complex interplay of genetic, dietary, environmental factors, and infections such as Helicobacter pylori. Despite the known risk factors, the role of gut microbiota in the development of gastric cancer remains insufficiently explored. This study aims to elucidate the causal relationship between gut microbiota and gastric cancer using a two-sample Mendelian Randomization (MR) approach.

Methods

Utilizing genome-wide association study (GWAS) summary data from the MiBioGen consortium and gastric cancer datasets, we selected instrumental variables for MR analysis based on their association with specific microbiota. We employed several MR methods, including inverse variance weighted (IVW), MR-Egger, weighted median, and others, to estimate the causal effects of gut microbiota diversity on the risk of developing gastric cancer.

Results

Our analysis identified significant associations between certain gut microbiota and gastric cancer risk. Specifically, taxa such as Clostridium sensustricto1 (OR = 0.540, 95%CI: 0.354-0.823, p = 0.004), Actinomycetales (OR = 0.756, 95%CI: 0.613-0.932, p = 0.009), Selenomonadales (OR = 0.816, 95%CI: 0.666-1.000, p < 0.05), Negativicutes (OR = 0.816, 95%CI: 0.666-1.000, p < 0.05), Rikenellaceae (OR = 0.863, 95%CI: 0.746-0.999, p = 0.048) were found to have a protective effect against gastric cancer. Conversely, an increased risk of gastric cancer was associated with the abundance of Roseburia (OR = 1.342, 95%CI: 1.071-1.681, p = 0.011), Family XI (OR = 1.132, 95%CI: 1.012-1.267, p = 0.030), and Eubacterium brachy group (OR = 1.207, 95%CI: 1.074-1.355, p = 0.002). The findings were robust across various MR methods and were not driven by any single SNP, indicating a genuine causal relationship.

Conclusion

Our studies have shown that there is a causal relationship between intestinal flora and gastric cancer at the genetic level. Clostridium sensustricto1, Actinomycetales, Rikenellaceae, Selenomonadales, Negativicutes, and Actinomycetaceae as having a protective role against GC, while Roseburia, Family XI, and Eubacterium brachy group were associated with an increased risk.

Analysis of the impact of immunotherapy efficacy and safety in patients with gastric cancer and liver metastasis

BACKGROUND

Gastric cancer (GC) is the fifth most common type of cancer and has the fourth highest death rate among all cancers. There is a lack of studies examining the impact of liver metastases on the effectiveness of immunotherapy in individuals diagnosed with GC.

AIM

To investigate the influence of liver metastases on the effectiveness and safety of immunotherapy in patients with advanced GC.

METHODS

This retrospective investigation collected clinical data of patients with advanced stomach cancer who had immunotherapy at our hospital from February 2021 to January 2023. The baseline attributes were compared using either the Chi-square test or the Fisher exact probability method. The chi-square test and Kaplan-Meier survival analysis were employed to assess the therapeutic efficacy and survival duration in GC patients with and without liver metastases.

RESULTS

The analysis comprised 48 patients diagnosed with advanced GC, who were categorized into two groups: A liver metastasis cohort (n = 20) and a non-liver metastatic cohort (n = 28). Patients with liver metastasis exhibited a more deteriorated physical condition compared to those without liver metastasis. The objective response rates in the cohort with metastasis and the cohort without metastasis were 15.0% and 35.7% (P > 0.05), respectively. Similarly, the disease control rates in these two cohorts were 65.0% and 82.1% (P > 0.05), respectively. The median progression-free survival was 5.0 months in one group and 11.2 months in the other group, with a hazard ratio of 0.40 and a significance level (P) less than 0.05. The median overall survival was 12.0 months in one group and 19.0 months in the other group, with a significance level (P) greater than 0.05.

CONCLUSION

Immunotherapy is less effective in GC patients with liver metastases compared to those without liver metastasis.

Role of Helicobacter pylori virulence factors and alteration of the Tumor Immune Microenvironment: challenges and opportunities for Cancer Immunotherapy

Various forms of malignancies have been linked to Helicobacter pylori. Despite advancements in chemotherapeutic and surgical approaches, the management of cancer, particularly at advanced stages, increasingly relies on the integration of immunotherapy. As a novel, safe therapeutic modality, immunotherapy harnesses the immune system of the patient to treat cancer, thereby broadening treatment options. However, there is evidence that H. pylori infection may influence the effectiveness of immunotherapy in various types of cancer. This association is related to H. pylori virulence factors and the tumor microenvironment. This review discusses the influence of H. pylori infection on immunotherapy in non-gastrointestinal and gastrointestinal tumors, the mechanisms underlying this relationship, and directions for the development of improved immunotherapy strategies.

The postbiotic sodium butyrate synergizes the antiproliferative effects of dexamethasone against the AGS gastric adenocarcinoma cells

A growing body of literature underlines the fundamental role of gut microbiota in the occurrence, treatment, and prognosis of cancer. In particular, the activity of gut microbial metabolites (also known as postbiotics) against different cancer types has been recently reported in several studies. However, their in-depth molecular mechanisms of action and potential interactions with standard chemotherapeutic drugs remain to be fully understood. This research investigates the antiproliferative activities of postbiotics- short-chain fatty acid (SCFA) salts, specifically magnesium acetate (MgA), sodium propionate (NaP), and sodium butyrate (NaB), against the AGS gastric adenocarcinoma cells. Furthermore, the potential synergistic interactions between the most active SCFA salt-NaB and the standard drug dexamethasone (Dex) were explored using the combination index model. The molecular mechanisms of the synergy were investigated using reactive oxygen species (ROS), flow cytometry and biochemometric and liquid chromatography-mass spectrometry (LC-MS)-driven proteomics analyses. NaB exhibited the most significant inhibitory effect (p < 0.05) among the tested SCFA salts against the AGS gastric cancer cells. Additionally, Dex and NaB exhibited strong synergy at a 2:8 ratio (40 μg/mL Dex + 2,400 μg/mL NaB) with significantly greater inhibitory activity (p < 0.05) compared to the mono treatments against the AGS gastric cancer cells. MgA and NaP reduced ROS production, while NaB exhibited pro-oxidative properties. Dex displayed antioxidative effects, and the combination of Dex and NaB (2,8) demonstrated a unique pattern, potentially counteracting the pro-oxidative effects of NaB, highlighting an interaction. Dex and NaB individually and in combination (Dex:NaB 40:2400 μg/mL) induced significant changes in cell populations, suggesting a shift toward apoptosis (p < 0.0001). Analysis of dysregulated proteins in the AGS cells treated with the synergistic combination revealed notable downregulation of the oncogene TNS4, suggesting a potential mechanism for the observed antiproliferative effects. These findings propose the potential implementation of NaB as an adjuvant therapy with Dex. Further investigations into additional combination therapies, in-depth studies of the molecular mechanisms, and in vivo research will provide deeper insights into the use of these postbiotics in cancer, particularly in gastric malignancies.

Effects of Helicobacter pylori infection on intestinal microbiota, immunity and colorectal cancer risk

Infecting about half of the world´s population, Helicobacter pylori is one of the most prevalent bacterial infections worldwide and the strongest known risk factor for gastric cancer. Although H. pylori colonizes exclusively the gastric epithelium, the infection has also been associated with various extragastric diseases, including colorectal cancer (CRC). Epidemiological studies reported an almost two-fold increased risk for infected individuals to develop CRC, but only recently, direct causal and functional links between the chronic infection and CRC have been revealed. Besides modulating the host intestinal immune response, H. pylori is thought to increase CRC risk by inducing gut microbiota alterations. It is known that H. pylori infection not only impacts the gastric microbiota at the site of infection but also leads to changes in bacterial colonization in the distal large intestine. Considering that the gut microbiome plays a driving role in CRC, H. pylori infection emerges as a key factor responsible for promoting changes in microbiome signatures that could contribute to tumor development. Within this review, we want to focus on the interplay between H. pylori infection, changes in the intestinal microbiota, and intestinal immunity. In addition, the effects of H. pylori antibiotic eradication therapy will be discussed.

Gut microbiota in gastric cancer: A determinant of etiology or a therapeutic approach?

The impact of the gut microbiota on the well-being and pathology of the host has garnered growing interest. In recent times, there has been a surge in understanding the mechanistic connections between the gut microbiota and cancer, particularly in relation to the genesis, progression, and therapeutic approaches for gastric cancer. The dysbiosis of the intestinal microbiome stands as a significant determinant in the etiology of gastric cancer. Currently, a preliminary consensus exists, although the precise mechanism remains incompletely understood. As research progresses, it becomes increasingly evident that intestinal flora significantly contributes to the therapeutic approach for gastric cancer. This paper gives a comprehensive review of the impact of intestinal flora on gastric cancer, examines the role of the intestinal microbiome in the management of gastric cancer, and elucidates the potential of utilizing the intestinal microbiome as an anti-tumor therapy, with an aim to furnish a point of reference and stimulate future research endeavors.

Microbial-Related Metabolites May Be Involved in Eight Major Biological Processes and Represent Potential Diagnostic Markers in Gastric Cancer

Metabolites associated with microbes regulate human immunity, inhibit bacterial colonization, and promote pathogenicity. Integrating microbe and metabolome research in GC provides a direction for understanding the microbe-associated pathophysiological process of metabolic changes and disease occurrence. The present study included 30 GC patients with 30 cancerous tissues and paired non-cancerous tissues (NCs) as controls. LC-MS/MS metabolomics and 16S rRNA sequencing were performed to obtain the metabolic and microbial characteristics. Integrated analysis of the microbes and metabolomes was conducted to explore the coexistence relationship between the microbial and metabolic characteristics of GC and to identify microbial-related metabolite diagnostic markers. The metabolic analysis showed that the overall metabolite distribution differed between the GC tissues and the NC tissues: 25 metabolites were enriched in the NC tissues and 42 metabolites were enriched in the GC tissues. The α and β microbial diversities were higher in the GC tissues than in the NC tissues, with 11 differential phyla and 52 differential genera. In the correlation and coexistence integrated analysis, 66 differential metabolites were correlated and coexisted, with specific differential microbes. The microbes in the GC tissue likely regulated eight metabolic pathways. In the efficacy evaluation of the microbial-related differential metabolites in the diagnosis of GC, 12 differential metabolites (area under the curve [AUC] >0.9) exerted relatively high diagnostic efficiency, and the combined diagnostic efficacy of 5 to 6 microbial-related differential metabolites was higher than the diagnostic efficacy of a single feature. Therefore, microbial diversity and metabolite distribution differed between the GC tissues and the NC tissues. Microbial-related metabolites may be involved in eight major metabolism-based biological processes in GC and represent potential diagnostic markers.

Gut Microbiota Dysbiosis in COVID-19: Modulation and Approaches for Prevention and Therapy

Inflammation and oxidative stress are critical underlying mechanisms associated with COVID-19 that contribute to the complications and clinical deterioration of patients. Additionally, COVID-19 has the potential to alter the composition of patients' gut microbiota, characterized by a decreased abundance of bacteria with probiotic effects. Interestingly, certain strains of these bacteria produce metabolites that can target the S protein of other coronaviruses, thereby preventing their transmission and harmful effects. At the same time, the presence of gut dysbiosis can exacerbate inflammation and oxidative stress, creating a vicious cycle that perpetuates the disease. Furthermore, it is widely recognized that the gut microbiota can metabolize various foods and drugs, producing by-products that may have either beneficial or detrimental effects. In this regard, a decrease in short-chain fatty acid (SCFA), such as acetate, propionate, and butyrate, can influence the overall inflammatory and oxidative state, affecting the prevention, treatment, or worsening of COVID-19. This review aims to explore the current evidence regarding gut dysbiosis in patients with COVID-19, its association with inflammation and oxidative stress, the molecular mechanisms involved, and the potential of gut microbiota modulation in preventing and treating SARS-CoV-2 infection. Given that gut microbiota has demonstrated high adaptability, exploring ways and strategies to maintain good intestinal health, as well as an appropriate diversity and composition of the gut microbiome, becomes crucial in the battle against COVID-19.