Influence of microbiota on immunity and immunotherapy for gastric and esophageal cancers

Gut microbiota mediated T cells regulation and autoimmune diseases

Gut microbiota regulates the immune system, the development and progression of autoimmune diseases (AIDs) and overall health. Recent studies have played a crucial part in understanding the specific role of different gut bacterial strains and their metabolites in different AIDs. Microbial signatures in AIDs are revealed by advanced sequencing and metabolomics studies. Microbes such as Faecalibacterium prausnitzii, Akkermansia muciniphila, Anaerostipes caccae, Bacteroides sp., Roseburia sp., Blautia sp., Blautia faecis, Clostridium lavalense, Christensenellaceae sp., Coprococcus sp., Firmicutes sp., Ruminococcaceae sp., Lachnospiraceae sp., Megamonas sp., Monoglobus sp., Streptococcus pneumoniae and Bifidobacterium sp. help maintain immune homeostasis; whereas, Prevotella copri, Ruminococcus gnavus, Lactobacillus salivarius, Enterococcus gallinarum, Elizabeth menigoseptica, Collinsella sp., Escherichia sp., Fusobacterium sp., Enterobacter ludwigii, Enterobacteriaceae sp., Proteobacteria, Porphyromonas gingivalis, Porphyromonas nigrescens, Dorea sp., and Clostridium sp. cause immuno-pathogenesis. A complex web of interactions is revealed by understanding the influence of gut microbiota on immune cells and various T cell subsets such as CD4+ T cells, CD8+ T cells, natural killer T cells, γδ T cells, etc. Certain AIDs, including rheumatoid arthritis, diabetes mellitus, atopic asthma, inflammatory bowel disease and non-alcoholic fatty liver disease exhibit a state of dysbiosis, characterized by alterations in microbial diversity and relative abundance of specific taxa. This review summarizes recent developments in understanding the role of certain microbiota composition in specific AIDs, and the factors affecting specific regulatory T cells through certain microbial metabolites and also focuses the potential application and therapeutic significance of gut microbiota-based interventions as novel adjunctive therapies for AIDs. Further research to determine the precise association of each gut bacterial strain in specific diseases is required.

Altered Microbiome Promotes Pro-Inflammatory Pathways in Oesophago-Gastric Tumourigenesis

INTRODUCTION

The upper gastrointestinal microbiome is a dynamic entity that is involved in numerous processes including digestion, production of vitamins and protection against pathogens. Many external and intrinsic factors may cause changes in the proportions of bacteria within the microbial community, termed 'dysbiosis'. A number of these have been identified as risk factors for a range of diseases, including oesophago-gastric carcinoma.

MATERIALS AND METHODS

A narrative review was conducted to elucidate the current evidence on the role of the microbiome in promoting oesophago-gastric tumourigenesis. Significant causes of dysbiosis including age, medications and GORD were examined and key pro-inflammatory pathways implicated in tumourigenesis and their interaction with the microbiome were described.

RESULTS AND DISCUSSION

An association between microbial dysbiosis and development of oesophago-gastric cancer may be mediated via activation of pro-inflammatory pathways, the inflammasome and the innate immune system. Advances in sequencing technology allow microbial communities to be fingerprinted by sequencing the 16S rRNA gene, enabling a deeper understanding of the genera that may be implicated in driving tumourigenesis.

CONCLUSIONS

Developing a greater understanding of the influence of the microbiota on oesophago-gastric tumourigenesis may enable advances to be made in the early detection of malignancy and in the development of novel systemic therapies, leading to improved rates of survival.

A comparative study of sampling methods in the detection of esophageal cancer-related microbiota

Esophageal cancer (EC) is a multifaceted disease. Our understanding of the involvement of esophageal microbiota in its pathogenesis and progression is limited, which is due to the lack of proper endoscopic sampling methods. Hereby, we conducted a comparative analysis of paired samples obtained through endoscopic brushing and cytosponge, aiming at assessing the feasibility of using cytosponge as a minimally invasive sampling way for studying esophageal microbiota. Our findings suggest that cytosponge sampling yielded significantly superior community richness and diversity compared to endoscopic brushing in both controls (non-cancerous) and EC individuals. The analysis of beta-diversity revealed distinct microbial community pattern in the genus diversity between the two sampling methods, underscoring the importance of selecting appropriate sampling methods to effectively characterize the esophageal microbiota. Specifically, Lactococcus and Serratia showed higher abundance in the samples collected by endoscopic brushing, while Alloprevotella and Leptotrichia were more enriched in the samples collected by cytosponge. These differences in dominant microbes were associated with metabolic pathways that particularly were related to host inflammation, such as pyruvate and glucose metabolisms. Notably, the phylogenetic levels of the microbiota indicated varied explanatory power for different detection purposes. This study underscores the substantial impact of sampling method selection on the acquisition of esophageal microbiota associated with the EC development, encompassing considerations of both abundance and diversity. This highlights the significance of selecting an appropriate sampling method for investigating the esophageal microbial status and studying the micro-environment in EC-related individuals.

IMPORTANCE

This study addresses a critical issue in esophageal cancer study by comparing two different sampling methods, endoscopic brushing and cytosponge, for investigating the esophageal microbiota. Our work highlights the suitability of the cytosponge technique as a minimally invasive sampling method for studying the esophageal microbiota and emphasizes the importance of selecting an appropriate sampling method to characterize the microbial community. Our findings have significant implications for advancing the understanding of the role of the esophageal microbiota in cancer development and will inform future research and clinical approaches in this field.

Distinct oral-associated gastric microbiota and Helicobacter pylori communities for spatial microbial heterogeneity in gastric cancer

The gastric microbial community plays a fundamental role in gastric cancer (GC), and the two main anatomical subtypes of GC, non-cardia and cardia GC, are associated with different risk factors (Helicobacter pylori for non-cardia GC). To decipher the different microbial spatial communities of GC, we performed a multicenter retrospective analysis to characterize the gastric microbiota in 223 GC patients, including H. pylori-positive or -negative patients, with tumors and paired adjacent normal tissues, using third-generation sequencing. In the independent validation cohort, both dental plaque and GC tumoral tissue samples were collected and sequenced. The prevalence of H. pylori and oral-associated bacteria was verified using fluorescence in situ hybridization (FISH) assays in GC tumoral tissues and matched nontumoral tissues. We found that the vertical distribution of the gastric microbiota, at the upper, middle, and lower third sites of GC, was likely an important factor causing microbial diversity in GC tumor tissues. The oral-associated microbiota cluster, which included Veillonella parvula, Streptococcus oralis, and Prevotella intermedia, was more abundant in the upper third of the GC. However, H. pylori was more abundant in the lower third of the GC and exhibited a significantly high degree of microbial correlation. The oral-associated microbiota module was co-exclusive with H. pylori in the lower third site of the GC tumoral tissue. Importantly, H. pylori-negative GC patients with oral-associated gastric microbiota showed worse overall survival, while the increase in microbial abundance in H. pylori-positive GC patients showed no difference in overall survival. The prevalence of V. parvula in both the dental plaque and GC tissue samples was concordant in the independent validation phase. We showed that the oral-associated species V. parvula and S. oralis were correlated with overall survival. Our study highlights the roles of the oral-associated microbiota in the upper third of the GC. In addition, oral-associated species may serve as noninvasive screening tools for the management of GC and an independent prognostic factor for H. pylori-negative GCs.

IMPORTANCE

Our study highlights the roles of the oral-associated microbiota in the upper third of gastric cancer (GC).We showed that the oral-associated species Veillonella parvula and Streptococcus oralis were correlated with overall survival. In addition, oral-associated species may serve as noninvasive screening tools for the management of GC and an independent prognostic factor for Helicobacter pylori-negative GCs.

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.

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.

The Role of Gut Dysbiosis in the Loss of Intestinal Immune Cell Functions and Viral Pathogenesis

The gut microbiome plays a critical role in maintaining overall health and immune function. However, dysbiosis, an imbalance in microbiome composition, can have profound effects on various aspects of human health, including susceptibility to viral infections. Despite numerous studies investigating the influence of viral infections on gut microbiome, the impact of gut dysbiosis on viral infection and pathogenesis remains relatively understudied. The clinical variability observed in SARS-CoV-2 and seasonal influenza infections, and the presence of natural HIV suppressors, suggests that host-intrinsic factors, including the gut microbiome, may contribute to viral pathogenesis. The gut microbiome has been shown to influence the host immune system by regulating intestinal homeostasis through interactions with immune cells. This review aims to enhance our understanding of how viral infections perturb the gut microbiome and mucosal immune cells, affecting host susceptibility and response to viral infections. Specifically, we focus on exploring the interactions between gamma delta (γδ) T cells and gut microbes in the context of inflammatory viral pathogenesis and examine studies highlighting the role of the gut microbiome in viral disease outcomes. Furthermore, we discuss emerging evidence and potential future directions for microbiome modulation therapy in the context of viral pathogenesis.

Current Progress on Predictive Biomarkers for Response to Immune Checkpoint Inhibitors in Gastric Cancer: How to Maximize the Immunotherapeutic Benefit?

Gastric cancer is the fifth most prevalent cancer and the fourth leading cause of cancer death globally. Delayed diagnosis and pronounced histological and molecular variations increase the complexity and challenge of treatment. Pharmacotherapy, which for a long time was systemic chemotherapy based on 5-fluorouracil, is the mainstay of management for advanced gastric cancer. Trastuzumab and programmed cell death 1 (PD-1) inhibitors have altered the therapeutic landscape, contributing to noticeably prolonged survivorship in patients with metastatic gastric cancer. However, research has revealed that immunotherapy is only beneficial to some individuals. Biomarkers, such as programmed cell death ligand 1 (PD-L1), microsatellite instability (MSI), and tumor mutational load (TMB), have been shown to correlate with immune efficacy in numerous studies and are increasingly employed for the selection of patients most likely to respond to immunotherapy. Gut microorganisms, genetic mutations like POLE/POLD1 and NOTCH4, tumor lymphoid infiltrating cells (TILs), and other novel biomarkers have the potential to develop into new predictors. Prospective immunotherapy for gastric cancer should be guided by a biomarker-driven precision management paradigm, and multidimensional or dynamic marker testing could be the way to go.

The interplay between Helicobacter pylori and the gut microbiota: An emerging driver influencing the immune system homeostasis and gastric carcinogenesis

The human gut microbiota are critical for preserving the health status because they are required for digestion and nutrient acquisition, the development of the immune system, and energy metabolism. The gut microbial composition is greatly influenced by the colonization of the recalcitrant pathogen Helicobacter pylori (H. pylori) and the conventional antibiotic regimens that follow. H. pylori is considered to be the main microorganism in gastric carcinogenesis, and it appears to be required for the early stages of the process. However, a non-H. pylori microbiota profile is also suggested, primarily in the later stages of tumorigenesis. On the other hand, specific groups of gut microbes may produce beneficial byproducts such as short-chain fatty acids (acetate, butyrate, and propionate) that can modulate inflammation and tumorigenesis pathways. In this review, we aim to present how H. pylori influences the population of the gut microbiota to modify the host immunity and trigger the development of gastric carcinogenesis. We will also highlight the effect of the gut microbiota on immunotherapeutic approaches such as immune checkpoint blockade in cancer treatment to present a perspective for further development of innovative therapeutic paradigms to prevent the progression of H. pylori-induced stomach cancer.

Microbiota and the Immune System-Actors in the Gastric Cancer Story

Simple Summary

Stomach cancer is one of the most commonly diagnosed cancers in the world. Although the number of new cases is decreasing year by year, the death rate for this type of cancer is still high. The heterogeneous course and the lack of symptoms in the early stages of the disease mean that the diagnosis is made late, which translates into a worse prognosis for such patients. That is why it is so important to analyze potential risk factors that may increase the risk of developing gastric cancer and to search for new effective methods of treatment. These requirements are met by the analysis of the composition of the gastric microbiota and its relationship with the immune system, which is a key element in the human anti-cancer fight. This publication was created to systematize the current knowledge on the impact of dysbiosis of human microbiota on the development and progression of gastric cancer. Particular emphasis was placed on taking into account the role of the immune system in this process.

Abstract

Gastric cancer remains one of the most commonly diagnosed cancers in the world, with a relatively high mortality rate. Due to the heterogeneous course of the disease, its diagnosis and treatment are limited and difficult, and it is associated with a reduced prognosis for patients. That is why it is so important to understand the mechanisms underlying the development and progression of this cancer, with particular emphasis on the role of risk factors. According to the literature data, risk factors include: changes in the composition of the stomach and intestinal microbiota (microbiological dysbiosis and the participation of Helicobacter pylori), improper diet, environmental and genetic factors, and disorders of the body’s immune homeostasis. Therefore, the aim of this review is to systematize the knowledge on the influence of human microbiota dysbiosis on the development and progression of gastric cancer, with particular emphasis on the role of the immune system in this process.

Cross-talk between the microbiome and chronic inflammation in esophageal cancer: potential driver of oncogenesis

Esophageal cancer (EC) is frequently considered a lethal malignancy and is often identified at a later stage. It is one of the major causes of cancer-related deaths globally. The conventional treatment methods like chemotherapy, radiotherapy, and surgery offer limited efficacy and poor clinical outcome with a less than 25% 5-year survival rate. The poor prognosis of EC persists despite the growth in the development of diagnostic and therapeutic modalities to treat EC. This underlines the need to elucidate the complex molecular mechanisms that drive esophageal oncogenesis. Apart from the role of the tumor microenvironment and its structural and cellular components in tumorigenesis, mounting evidence points towards the involvement of the esophageal microbiome, inflammation, and their cross-talk in promoting esophageal cancer. The current review summarizes recent research that delineates the underlying molecular mechanisms by which the microbiota and inflammation promote the pathophysiology of esophageal cancer, thus unraveling targets for potential therapeutic intervention.

Impact of the Tumor Microenvironment for Esophageal Tumor Development—An Opportunity for Prevention?

Simple Summary

Researchers increasingly appreciate the tumor microenvironment (TME) for its role in the development and therapy resistance of cancers like esophageal adenocarcinoma. A better understanding of the TME fueling carcinogenesis is necessary for tailored prevention and therapies. Here, we highlight recent insights into tumor initiation, interactions with the immune system and possible novel preventative measures.

Abstract

Despite therapeutical advancements, and in contrast to other malignancies, esophageal adenocarcinoma (EAC) prognosis remains dismal while the incidence has markedly increased worldwide over the past decades. EAC is a malignancy of the distal esophageal squamous epithelium at the squamocolumnar junction with gastric cells expanding into the esophagus. Most EAC patients have a history of Barret’s esophagus (BE), a metaplastic adaption to chronic reflux, initially causing an inflammatory microenvironment. Thus, the immune system is highly involved early on in disease development and progression. Normally, anti-tumor immunity could prevent carcinogenesis but in rare cases BE still progresses over a dysplastic intermediate state to EAC. The inflammatory milieu during the initial esophagitis phase changes to a tolerogenic immune environment in BE, and back to pro-inflammatory conditions in dysplasia and finally to an immune-suppressive tumor microenvironment in EAC. Consequently, there is a huge interest in understanding the underpinnings that lead to the inflammation driven stepwise progression of the disease. Since knowledge about the constellations of the various involved cells and signaling molecules is currently fragmentary, a comprehensive description of these changes is needed, allowing better preventative measures, diagnosis, and novel therapeutic targets.

Developing a Mathematical Model of Intracellular Calcium Dynamics for Evaluating Combined Anticancer Effects of Afatinib and RP4010 in Esophageal Cancer

Targeting dysregulated Ca2+ signaling in cancer cells is an emerging chemotherapy approach. We previously reported that store-operated Ca2+ entry (SOCE) blockers, such as RP4010, are promising antitumor drugs for esophageal cancer. As a tyrosine kinase inhibitor (TKI), afatinib received FDA approval to be used in targeted therapy for patients with EGFR mutation-positive cancers. While preclinical studies and clinical trials have shown that afatinib has benefits for esophageal cancer patients, it is not known whether a combination of afatinib and RP4010 could achieve better anticancer effects. Since TKI can alter intracellular Ca2+ dynamics through EGFR/phospholipase C-γ pathway, in this study, we evaluated the inhibitory effect of afatinib and RP4010 on intracellular Ca2+ oscillations in KYSE-150, a human esophageal squamous cell carcinoma cell line, using both experimental and mathematical simulations. Our mathematical simulation of Ca2+ oscillations could fit well with experimental data responding to afatinib or RP4010, both separately or in combination. Guided by simulation, we were able to identify a proper ratio of afatinib and RP4010 for combined treatment, and such a combination presented synergistic anticancer-effect evidence by experimental measurement of intracellular Ca2+ and cell proliferation. This intracellular Ca2+ dynamic-based mathematical simulation approach could be useful for a rapid and cost-effective evaluation of combined targeting therapy drugs.

Microbiome composition indicate dysbiosis and lower richness in tumor breast tissues compared to healthy adjacent paired tissue, within the same women

Background

Breast cancer (BC) is the most common malignancy in women, in whom it reaches 20% of the total neoplasia incidence. Most BCs are considered sporadic and a number of factors, including familiarity, age, hormonal cycles and diet, have been reported to be BC risk factors. Also the gut microbiota plays a role in breast cancer development. In fact, its imbalance has been associated to various human diseases including cancer although a consequential cause-effect phenomenon has never been proven.

Methods

The aim of this work was to characterize the breast tissue microbiome in 34 women affected by BC using an NGS-based method, and analyzing the tumoral and the adjacent non-tumoral tissue of each patient.

Results

The healthy and tumor tissues differed in bacterial composition and richness: the number of Amplicon Sequence Variants (ASVs) was higher in healthy tissues than in tumor tissues (p = 0.001). Moreover, our analyses, able to investigate from phylum down to species taxa for each sample, revealed major differences in the two richest phyla, namely, Proteobacteria and Actinobacteria. Notably, the levels of Actinobacteria and Proteobacteria were, respectively, higher and lower in healthy with respect to tumor tissues.

Conclusions

Our study provides information about the breast tissue microbial composition, as compared with very closely adjacent healthy tissue (paired samples within the same woman); the differences found are such to have possible diagnostic and therapeutic implications; further studies are necessary to clarify if the differences found in the breast tissue microbiome are simply an association or a concausative pathogenetic effect in BC. A comparison of different results on similar studies seems not to assess a universal microbiome signature, but single ones depending on the environmental cohorts’ locations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-09074-y.

Interdisciplinary insights into the link between gut microbiome and gastric carcinogenesis-what is currently known?

Currently, gastric cancer is one of the leading death-related cancer globally. The etiopathogenesis of gastric cancer is multifactorial and includes among others dysbiotic alterations of gastric microbiota. Molecular techniques revealed that stomach is not a sterile organ and it is resides with ecosystem of microbes. Due to the fact that the role of Helicobacter pylori infection in development of gastric cancer is established and well-studied, this paper is mainly focused on the role of other bacterial as well as viral and fungal gut microbiota imbalance in gastric carcinogenesis. Notably, not only the composition of gastric microbiota may play an important role in development of gastric cancer, but also its activity. Microbial metabolites, such as short-chain fatty acids, polyamines, N-nitroso compounds, and lactate, may significantly affect gastric carcinogenesis. Therefore, this paper discussed aforementioned aspects with the interdisciplinary insights (regarding also immunological point of view) into the association between gut microbiome and gastric carcinogenesis based on up-to-date studies.

A new biological triangle in cancer: intestinal microbiota, immune checkpoint inhibitors and antibiotics

Cancer immunotherapy has revolutionized the treatment of many malignant tumors. Although immune checkpoint inhibitors (ICIs) can reactivate the anti-tumor activity of immune cells, sensitivity to immune checkpoint inhibitor therapy depends on the complex tumor immune processes. In recent years, numerous researches have demonstrated the role of intestinal microbiota in immunity and metabolism of the tumor microenvironment, as well as the efficacy of immunotherapy. Epidemiological studies have further demonstrated the efficacy of antibiotic therapy on the probability of patients' response to ICIs and predictability of the short-term survival of cancer patients. Disturbance to the intestinal microbiota significantly affects ICIs-mediated immune reconstitution and is considered a possible mechanism underlying the development of adverse effects during antibiotic-based ICIs treatment. Intestinal microbiota, antibiotics, and ICIs have gradually become important considerations for the titer of immunotherapy. In the case of immunotherapy, the rational use of antibiotics and intestinal microbiota is expected to yield a better prognosis for patients with malignant tumors.

Characterization of the Oral and Esophageal Microbiota in Esophageal Precancerous Lesions and Squamous Cell Carcinoma

Important evidence indicates that the microbiota plays a key role in esophageal squamous cell carcinoma (ESCC). Here, paired saliva and brush specimens were obtained from 276 participants undergoing upper gastrointestinal endoscopic examination before or during screening for upper gastrointestinal (UGI) cancer. The esophageal microbiota was investigated by 16S rRNA gene profiling and next-generation sequencing. We observed that as the disease progressed, the α diversity in the saliva and cell brush samples decreased. Linear discriminant analysis effect size (LEfSe) results showed that in both the saliva and cell brush specimens, Granulicatella, Rothia, Streptococcus, Gemella, Leptotrichia and Schaalia were common biomarkers in patients with low-grade dysplasia, Lactobacillus was a common biomarker in patients with high-grade dysplasia, and Bosea, Solobacterium, Gemella, and Peptostreptococcus were common biomarkers in patients with esophageal cancer. The top 3 genera in the saliva and cell brush specimens had areas under the curve (AUCs) of 87.16 and 89.13%, respectively, to distinguish ESCC patients from normal people. The PICRUSt2 results identified in brush samples that patients with ESCC had decreased nitrate reductase functions. Our results suggest that future studies can focus on the function of the characteristic bacteria in ESCC.

The effects of smoking and drinking on the oral and esophageal microbiota of healthy people

Background

To explore the effects of smoking and drinking on the microbiota in the saliva and three segments of the esophagus (upper, middle, and lower) in healthy individuals.

Methods

Paired saliva and brush specimens were obtained from 76 participants who underwent upper gastrointestinal (UGI) endoscopic examination for UGI cancer screening. The esophageal microbiota was investigated by 16S rRNA gene profiling via next-generation sequencing.

Results

The saliva samples from non-smoking and non-drinking participants had a greater abundance of Neisseria, Prevotella, Porphyromonas, and Rothia, and lower levels of Streptococcus, Actinobacillus, and Haemophilus compared to the esophagus. There were no significant differences in the abundance of most bacterial genera in the upper, middle, and lower oesophagus. Similarly, in the saliva of patients who smoke and drink, there was a higher prevalence of Neisseria, Prevotella, Porphyromonas, Fusobacterium, and Rothia, and a lower prevalence of Streptococcus, Actinobacillus, and Haemophilus compared to the esophagus. There were no significant differences in the abundance of most genera in the upper, middle, and lower esophagus of patients with a history of drinking and smoking. There were slight differences in the microbiota between smoking and drinking individuals and non-smoking and non-drinking individuals.

Conclusions

This pilot study demonstrated microbial diversity at different taxonomic levels in the oral cavity and esophagus of non-drinking and non-smoking individuals, as well as healthy people who drink and smoke . There was a slight difference in the microbiota between non-drinking and non-smoking people and individuals with a history of drinking and smoking. These results suggested that oral or esophageal cancer caused by smoking and drinking may not be mediated by mechanisms that affect surface microorganisms.

The Role of Gut Microbiota in Tumor Immunotherapy

Tumor immunotherapy is the fourth therapy after surgery, chemotherapy, and radiotherapy. It has made great breakthroughs in the treatment of some epithelial tumors and hematological tumors. However, its adverse reactions are common or even more serious, and the response rate in some solid tumors is not satisfactory. With the maturity of genomics and metabolomics technologies, the effect of intestinal microbiota in tumor development and treatment has gradually been recognized. The microbiota may affect tumor immunity by regulating the host immune system and tumor microenvironment. Some bacteria help fight tumors by activating immunity, while some bacteria mediate immunosuppression to help cancer cells escape from the immune system. More and more studies have revealed that the effects and complications of tumor immunotherapy are related to the composition of the gut microbiota. The composition of the intestinal microbiota that is sensitive to treatment or prone to adverse reactions has certain characteristics. These characteristics may be used as biomarkers to predict the prognosis of immunotherapy and may also be developed as “immune potentiators” to assist immunotherapy. Some clinical and preclinical studies have proved that microbial intervention, including microbial transplantation, can improve the sensitivity of immunotherapy or reduce adverse reactions to a certain extent. With the development of gene editing technology and nanotechnology, the design and development of engineered bacteria that contribute to immunotherapy has become a new research hotspot. Based on the relationship between the intestinal microbiota and immunotherapy, the correct mining of microbial information and the development of reasonable and feasible microbial intervention methods are expected to optimize tumor immunotherapy to a large extent and bring new breakthroughs in tumor treatment.

Impact of Environmental and Pharmacologic Changes on the Upper Gastrointestinal Microbiome

Diseases of the upper gastrointestinal tract have become more prevalent over time. Mechanisms of disease formation are still only partially understood. Recent literature has shown that the surrounding microbiome affects the propensity for disease formation in various parts of the upper gastrointestinal tract. A review was performed of any literature to our best knowledge concerning the effects of pharmacologic agents, environmental changes, and surgical intervention on the microbiome of the upper gastrointestinal tract. Searches of the literature were performed using specific keywords related to drugs, surgical procedures, and environmental factors. Many prescription and nonprescription drugs that are commonly used have varying effects on the upper gastrointestinal tract. Proton pump inhibitors may affect the relative prevalence of some organisms in the lower esophagus and have less effect in the proximal esophagus. Changes in the esophageal microbiome correlate with some esophageal diseases. Drugs that induce weight loss have also been shown to affect the microbiomes of the esophagus and stomach. Common surgical procedures are associated with shifts in the microbial community in the gastrointestinal tract. Environmental factors have been shown to affect the microbiome in the upper gastrointestinal tract, as geographic differences correlate with alterations in the microbiome of the gastrointestinal tract. Understanding the association of environmental and pharmacologic changes on the microbiome of the upper gastrointestinal tract will facilitate treatment plans to reduce morbidity from disease.

Store-Operated Calcium Channels as Drug Target in Gastroesophageal Cancers

Gastroesophageal cancers, including tumors occurring in esophagus and stomach, usually have poor prognosis and lack effective chemotherapeutic drugs for treatment. The association between dysregulated store-operated calcium entry (SOCE), a key intracellular Ca2+ signaling pathway and gastroesophageal cancers are emerging. This review summarizes the recent advances in understanding the contribution of SOCE-mediated intracellular Ca2+ signaling to gastroesophageal cancers. It assesses the pathophysiological role of each component in SOCE machinery, such as Orais and STIMs in the cancer cell proliferation, migration, and invasion as well as stemness maintenance. Lastly, it discusses efforts towards development of more specific and potent SOCE inhibitors, which may be a new set of chemotherapeutic drugs appearing at the horizon, to provide either targeted therapy or adjuvant treatment to overcome drug resistance for gastroesophageal cancers.