Regulatory T Cells and Plasmacytoid Dendritic Cells Within the Tumor Microenvironment in Gastric Cancer Are Correlated With Gastric Microbiota Dysbiosis: A Preliminary Study

Isolation and whole genomic analysis of mesophilic bacterium Pseudoglutamicibacter cumminsii in epithelial mesothelioma

The relationship between bacteria and tumors has been the hot spot of clinical research in recent years. Pseudoglutamicibacter cumminsii is an aerobic Gram-positive bacterium commonly found in soil. Recent studies have identified P. cumminsii in patients with cutaneous and urinary tract infections. However, little is known on its pathogenesis as well as involvement in other clinical symptoms. In this study, we first report the isolation of P. cumminsii in blood of an epithelial mesothelioma patient. The clinical and laboratory characteristics of P. cumminsii were first described and evaluated. The pure colony of P. cumminsii was then identified using automated microorganism identification system and mass spectrum. The whole genome of the newly identified strain was sequenced with third generation sequencing (TGS). The assembled genome was further annotated and analyzed. Whole genomic and comparative genomic analysis revealed that the isolated P. cumminsii strain in this study had a genome size of 2,179,930 bp and had considerable unique genes compared with strains reported in previous findings. Further phylogenetic analysis showed that this strain had divergent phylogenetic relationship with other P. cumminsii strains. Based on these results, the newly found P. cumminsii strain was named P. cumminsii XJ001 (PC1). Virulence analysis identified a total of 71 pathogenic genes with potential roles in adherence, immune modulation, nutrition/metabolism, and regulation in PC1. Functional analysis demonstrated that the annotated genes in PC1 were mainly clustered into amino acid metabolism (168 genes), carbohydrate metabolism (107 genes), cofactor and vitamin metabolisms (98 genes), and energy metabolism (68 genes). Specifically, six genes including yodJ, idh, katA, pyk, sodA, and glsA were identified within cancer pathways, and their corresponding homologous genes have been documented with precise roles in human cancer. Collectively, the above results first identified P. cumminsii in the blood of tumor patients and further provide whole genomic landscape of the newly identified PC1 strain, shedding light on future studies of bacteria in tumorigenesis.

Glycolysis, the sweet appetite of the tumor microenvironment

Cancer cells display an altered metabolic phenotype, characterised by increased glycolysis and lactate production, even in the presence of sufficient oxygen - a phenomenon known as the Warburg effect. This metabolic reprogramming is a crucial adaptation that enables cancer cells to meet their elevated energy and biosynthetic demands. Importantly, the tumor microenvironment plays a pivotal role in shaping and sustaining this metabolic shift in cancer cells. This review explores the intricate relationship between the tumor microenvironment and the Warburg effect, highlighting how communication within this niche regulates cancer cell metabolism and impacts tumor progression and therapeutic resistance. We discuss the potential of targeting the Warburg effect as a promising therapeutic strategy, with the aim of disrupting the metabolic advantage of cancer cells and enhancing our understanding of this complex interplay within the tumor microenvironment.

Altered gut microbiota and systemic immunity in Chinese patients with schizophrenia comorbid with metabolic syndrome

BACKGROUND

Metabolic syndrome (MetS) is highly prevalent in individuals with schizophrenia (SZ), leading to negative consequences like premature mortality. Gut dysbiosis, which refers to an imbalance of the microbiota, and chronic inflammation are associated with both SZ and MetS. However, the relationship between gut dysbiosis, host immunological dysfunction, and SZ comorbid with MetS (SZ-MetS) remains unclear. This study aims to explore alterations in gut microbiota and their correlation with immune dysfunction in SZ-MetS, offering new insights into its pathogenesis.

METHODS AND RESULTS

We enrolled 114 Chinese patients with SZ-MetS and 111 age-matched healthy controls from Zhejiang, China, to investigate fecal microbiota using Illumina MiSeq sequencing targeting 16 S rRNA gene V3-V4 hypervariable regions. Host immune responses were assessed using the Bio-Plex Pro Human Cytokine 27-Plex Assay to examine cytokine profiles. In SZ-MetS, we observed decreased bacterial α-diversity and significant differences in β-diversity. LEfSe analysis identified enriched acetate-producing genera (Megamonas and Lactobacillus), and decreased butyrate-producing bacteria (Subdoligranulum, and Faecalibacterium) in SZ-MetS. These altered genera correlated with body mass index, the severity of symptoms (as measured by the Scale for Assessment of Positive Symptoms and Scale for Assessment of Negative Symptoms), and triglyceride levels. Altered bacterial metabolic pathways related to lipopolysaccharide biosynthesis, lipid metabolism, and various amino acid metabolism were also found. Additionally, SZ-MetS exhibited immunological dysfunction with increased pro-inflammatory cytokines, which correlated with the differential genera.

CONCLUSION

These findings suggested that gut microbiota dysbiosis and immune dysfunction play a vital role in SZ-MetS development, highlighting potential therapeutic approaches targeting the gut microbiota. While these therapies show promise, further mechanistic studies are needed to fully understand their efficacy and safety before clinical implementation.

Intratumoral Microbiome: Foe or Friend in Reshaping the Tumor Microenvironment Landscape?

The role of the microbiome in cancer and its crosstalk with the tumor microenvironment (TME) has been extensively studied and characterized. An emerging field in the cancer microbiome research is the concept of the intratumoral microbiome, which refers to the microbiome residing within the tumor. This microbiome primarily originates from the local microbiome of the tumor-bearing tissue or from translocating microbiome from distant sites, such as the gut. Despite the increasing number of studies on intratumoral microbiome, it remains unclear whether it is a driver or a bystander of oncogenesis and tumor progression. This review aims to elucidate the intricate role of the intratumoral microbiome in tumor development by exploring its effects on reshaping the multileveled ecosystem in which tumors thrive, the TME. To dissect the complexity and the multitude of layers within the TME, we distinguish six specialized tumor microenvironments, namely, the immune, metabolic, hypoxic, acidic, mechanical and innervated microenvironments. Accordingly, we attempt to decipher the effects of the intratumoral microbiome on each specialized microenvironment and ultimately decode its tumor-promoting or tumor-suppressive impact. Additionally, we portray the intratumoral microbiome as an orchestrator in the tumor milieu, fine-tuning the responses in distinct, specialized microenvironments and remodeling the TME in a multileveled and multifaceted manner.

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.

The Multifaceted Functionality of Plasmacytoid Dendritic Cells in Gastrointestinal Cancers: A Potential Therapeutic Target?

Gastrointestinal (GI) tumors pose a significant global health burden, necessitating the exploration of novel therapeutic approaches. Plasmacytoid dendritic cells (pDCs) play a crucial role in tumor immunity, exhibiting both anti-tumor and pro-tumor effects. This review aims to summarize the role of pDCs in different types of GI tumors and assess their potential as therapeutic targets. In gastric cancer, hepatocellular carcinoma, and intrahepatic cholangiocarcinoma, increased infiltration of pDCs was associated with a worse outcome, whereas in esophageal cancer, pancreatic cancer, and colorectal cancer, pDC infiltration improved the outcome. Initial animal studies of gastric cancer and hepatocellular carcinoma showed that pDCs could be a successful therapeutic target. In conclusion, pDCs play a multifaceted role in GI tumors, influencing both anti-tumor immunity and tumor progression. Further research is needed to optimize their clinical application and explore combinatorial approaches.

Interaction between intestinal flora and gastric cancer in tumor microenvironment

Gastric Cancer (GC) is a prevalent malignancy globally and is the third leading cause of cancer-related deaths. Recent researches focused on the correlation between intestinal flora and GC. Studies indicate that bacteria can influence the development of gastrointestinal tumors by releasing bacterial extracellular vesicles (BEVs). The Tumor microenvironment (TME) plays an important role in tumor survival, with the interaction between intestinal flora, BEVs, and TME directly impacting tumor progression. Moreover, recent studies have demonstrated that intestinal microflora and BEVs can modify TME to enhance the effectiveness of antitumor drugs. This review article provides an overview and comparison of the biological targets through which the intestinal microbiome regulates TME, laying the groundwork for potential applications in tumor diagnosis, treatment, and prognosis.

Unveiling the gastric microbiota: implications for gastric carcinogenesis, immune responses, and clinical prospects

High-throughput sequencing has ushered in a paradigm shift in gastric microbiota, breaking the stereotype that the stomach is hostile to microorganisms beyond H. pylori. Recent attention directed toward the composition and functionality of this 'community' has shed light on its potential relevance in cancer. The microbial composition in the stomach of health displays host specificity which changes throughout a person's lifespan and is subject to both external and internal factors. Distinctive alterations in gastric microbiome signature are discernible at different stages of gastric precancerous lesions and malignancy. The robust microbes that dominate in gastric malignant tissue are intricately implicated in gastric cancer susceptibility, carcinogenesis, and the modulation of immunosurveillance and immune escape. These revelations offer fresh avenues for utilizing gastric microbiota as predictive biomarkers in clinical settings. Furthermore, inter-individual microbiota variations partially account for differential responses to cancer immunotherapy. In this review, we summarize current literature on the influence of the gastric microbiota on gastric carcinogenesis, anti-tumor immunity and immunotherapy, providing insights into potential clinical applications.

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.

Intratumoral microbiome is associated with gastric cancer prognosis and therapy efficacy

The role of the intratumoral microbiome in gastric cancer (GC) has not been comprehensively assessed. Here, we explored the relationship between the microbial community and GC prognosis and therapy efficacy. Several cancer-associated microbial characteristics were identified, including increased α-diversity, differential β-diversity, and decreased Helicobacter pylori abundance. After adjusting for clinical features, prognostic analysis revealed 2 phyla, 14 genera, and 5 species associated with the overall survival of patients with GC. Additionally, 2 phyla, 14 genera, and 6 species were associated with adjuvant chemotherapy (ACT) efficacy in patients with stage II - III GC. Furthermore, we classified GC microbiome structures into three microbial subtypes (MS1, MS2 and MS3) with distinguishing features. The MS1 subtype exhibited high immune activity and enrichment of microbiota related to immunotherapy and butyric acid-producing, as well as potential benefits in immunotherapy. MS2 featured the highest α-diversity and activation of the TFF pathway, MS3 was characterized by epithelial-mesenchymal transition and was associated with poor prognosis and reduced ACT efficacy. Collectively, the results of this study provide valuable insights into the microbial characteristics associated with GC prognosis and therapy efficacy.

Microbes mediated immunogenic cell death in cancer immunotherapy

Immunogenic cell death (ICD) is one of the 12 distinct cell death forms, which can trigger immune system to fight against cancer cells. During ICD, a number of cellular changes occur that can stimulate an immune response, including the release of molecules called damage-associated molecular patterns (DAMPs), signaling to immune cells to recognize and attack cancer cells. By virtue of their pivotal role in immune surveillance, ICD-based drug development has been a new approach to explore novel therapeutic combinations and personalized strategies in cancer therapy. Several small molecules and microbes can induce ICD-relevant signals and cause cancer cell death. In this review, we highlighted the role of microbe-mediate ICD in cancer immunotherapy and described the mechanisms through which microbes might serve as ICD inducers in cancer treatment. We also discussed current attempts to combine microbes with chemotherapy regimens or immune checkpoint inhibitors (ICIs) in the treatment of cancer patients. We surmise that manipulation of microbes may guide personalized therapeutic interventions to facilitate anticancer immune response.

Profiles of biliary microbiota in biliary obstruction patients with Clonorchis sinensis infection

Background

Clonorchis sinensis (C. sinensis) is a epidemiologically significant food-borne parasite, causing several hepatobiliary diseases. Biliary microbiota community structure might be influenced by infection with pathogens. However, the biliary microbiome of biliary obstruction patients infected with C. sinensis is still an unexplored aspect.

Methods

A total of 50 biliary obstruction patients were enrolled, including 24 infected with C. sinensis and 26 non-infected subjects. The bile samples were collected by Endoscopic Retrograde Cholangiopancretography. Biliary microbiota alteration was analyzed through high-throughput 16S ribosomal RNA (rRNA) gene sequencing.

Results

Our findings revealed that there was significant increase in both richness and diversity, as well as changes in the taxonomic composition of the biliary microbiota of C. sinensis infected patients. At the phylum level, C. sinensis infection induced Proteobacteria increased and Firmicutes reduced. At the genus level, the relative abundance of Pseudomonas and Staphylococcus increased significantly, while Enterococcus decreased prominently in infected groups (P < 0.05). The PICRUSt analysis further showed remarkably different metabolic pathways between the two groups.

Conclusion

C. sinensis infection could modify the biliary microbiota, increasing the abundance and changing the phylogenetic composition of bacterial in biliary obstruction patients. This study may help deepen the understanding of the host-biliary microbiota interplay with C. sinensis infection on the background of biliary obstruction and provide new insights into understanding the pathogenesis of clonorchiasis.

Exploration of gastric carcinogenesis from the relationship between bile acids and intestinal metaplasia and intragastric microorganisms (H. pylori and non-H. pylori)

Gastric cancer (GC) is a prevalent form of cancer, with Helicobacter pylori (H. pylori) infection being the most common risk factor. Recent studies have highlighted the role of long-term irritation of the gastric mucosa caused by bile reflux in the development of cancer. Bile acids (BAs), which are a significant component in bile reflux, have the potential to promote gastric carcinogenesis through various mechanisms. These mechanisms include the induction of intestinal metaplasia (IM), inhibition of H. pylori activity, modification of H. pylori colonization, and alteration of the abundance and composition of microorganisms in the stomach. Defining the mechanism of bile acid-induced gastric carcinogenesis could potentially be an effective approach to prevent GC. Hence, this paper aims to review the mechanism of bile acid-induced IM, the association between BAs and H. pylori infection as well as microorganisms in the stomach, and the correlation between BAs and gastric carcinogenesis. The ultimate goal is to elucidate the role of BAs in the development of GC.

Diabetes Mellitus and Gastric Cancer: Correlation and Potential Mechanisms

This review summarizes the correlation between diabetes mellitus (DM) and gastric cancer (GC) from the perspectives of epidemiology, drug use, and potential mechanisms. The association between DM and GC is inconclusive, and the positive direction of the association reported in most published meta-analyses suggests that DM may be an independent risk factor for GC. Many clinical investigations have shown that people with DM and GC who undergo gastrectomy may have better glycemic control. The potential link between DM and GC may involve the interaction of multiple common risk factors, such as obesity, hyperglycemia and hyperinsulinemia, H. pylori infection, and the use of metformin. Although in vitro and in vivo data support that H. pylori infection status and metformin can influence GC risk in DM patients, there are conflicting results. Patient survival outcomes are influenced by multiple factors, so further research is needed to identify the patients who may benefit.

Leveraging existing 16S rRNA microbial data to identify diagnostic biomarker in Chinese patients with gastric cancer: a systematic meta-analysis

IMPORTANCE

Gastric cancer is a significant and growing health problem in China. Studies have revealed significant differences in gastric microbiota between patients with gastric cancer and non-cancerous patients, suggesting that microbiota may play a role in tumorigenesis. In this meta-analysis, existing 16S rRNA microbial data were analyzed to find combinations consisting of five genera, which had good efficacy in distinguishing gastric cancer from non-cancerous patients in multiple types of samples. These results lend support to the use of microbial markers in detecting gastric cancer. Moreover, these biomarkers are plausible candidates for further mechanistic research into the role of the microbiota in tumorigenesis.

Emerging roles of plasmacytoid dendritic cell crosstalk in tumor immunity

Plasmacytoid dendritic cells (pDCs) are a pioneer cell type that produces type I interferon (IFN-I) and promotes antiviral immune responses. However, they are tolerogenic and, when recruited to the tumor microenvironment (TME), play complex roles that have long been a research focus. The interactions between pDCs and other components of the TME, whether direct or indirect, can either promote or hinder tumor development; consequently, pDCs are an intriguing target for therapeutic intervention. This review provides a comprehensive overview of pDC crosstalk in the TME, including crosstalk with various cell types, biochemical factors, and microorganisms. An in-depth understanding of pDC crosstalk in TME should facilitate the development of novel pDC-based therapeutic methods.

Advances in the role of gut microbiota in the regulation of the tumor microenvironment (Review)

As a protector of human health, the gut microbiota plays an important role in the development of the immune system during childhood, and the regulation of dietary habits, metabolism and immune system during adulthood. Dysregulated gut flora is not pathogenic, but it can weaken the protective effect of the immune system and cause various diseases. The tumor microenvironment is a physiological environment formed during tumor growth, which provides nutrients and growth factors necessary for tumor growth. As an important factor affecting the tumor microenvironment, the intestinal microflora affects the development of tumors through the mechanisms of gut and microflora metabolites, gene toxins and signaling pathways. The present article aimed to review the components and mechanisms of action, clinical applications, and biological targets of gut microbiota in the regulation of the tumor microenvironment. The present review provides novel insights for the future use of intestinal flora, to regulate the tumor microenvironment, to intervene in the occurrence, development, treatment and prognosis of tumors.

The role of gastric microecological dysbiosis in gastric carcinogenesis

Gastric cancer (GC) is the leading cause of cancer-related death worldwide, and reducing its mortality has become an urgent public health issue. Gastric microecological dysbiosis (including bacteria, fungi, viruses, acid suppressants, antibiotics, and surgery) can lead to gastric immune dysfunction or result in a decrease in dominant bacteria and an increase in the number and virulence of pathogenic microorganisms, which in turn promotes development of GC. This review analyzes the relationship between gastric microecological dysbiosis and GC, elucidates dynamic alterations of the microbiota in Correa's cascade, and identifies certain specific microorganisms as potential biomarkers of GC to aid in early screening and diagnosis. In addition, this paper presents the potential of gastric microbiota transplantation as a therapeutic target for gastric cancer, providing a new direction for future research in this field.

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

Gastric cancer (GC) is one of the most common cancers, leading to the deaths of millions of people worldwide. Therefore, early detection and effective therapeutic strategies are of great value for decreasing the occurrence of advanced GC. The human microbiota is involved not only in the maintenance of physiological conditions, but also in human diseases such as obesity, diabetes, allergic and atopic diseases, and cancer. Currently, the composition of the bacteria in the host, their functions, and their influence on disease progression and treatment are being discussed. Previous studies on the gut microbiome have mostly focused on Helicobacter pylori (Hp) owing to its significant role in the development of GC. Nevertheless, the enrichment and diversity of other bacteria that can modulate the tumor microenvironment are involved in the progression of GC and the efficacy of immunotherapy. This review provides systematic insight into the components of the gut microbiota and their application in GC, including the specific bacteria of GC, their immunoregulatory effect, and their diagnostic value. Furthermore, we discuss the relationship between the metabolism of microbes and their potential applications, which may serve as a new approach for the diagnosis and treatment of GC.

Gastric microbiota: an emerging player in gastric cancer

Gastric cancer (GC) is a common cancer worldwide with a high mortality rate. Many microbial factors influence GC, of which the most widely accepted one is Helicobacter pylori (H. pylori) infection. H. pylori causes inflammation, immune reactions and activation of multiple signaling pathways, leading to acid deficiency, epithelial atrophy, dysplasia and ultimately GC. It has been proved that complex microbial populations exist in the human stomach. H. pylori can affect the abundance and diversity of other bacteria. The interactions among gastric microbiota are collectively implicated in the onset of GC. Certain intervention strategies may regulate gastric homeostasis and mitigate gastric disorders. Probiotics, dietary fiber, and microbiota transplantation can potentially restore healthy microbiota. In this review, we elucidate the specific role of the gastric microbiota in GC and hope these data can facilitate the development of effective prevention and therapeutic approaches for GC.

Interplay between Signaling Pathways and Tumor Microenvironment Components: A Paradoxical Role in Colorectal Cancer

The study of the tumor microenvironment (TME) has become an important part of colorectal cancer (CRC) research. Indeed, it is now accepted that the invasive character of a primary CRC is determined not only by the genotype of the tumor cells, but also by their interactions with the extracellular environment, which thereby orchestrates the development of the tumor. In fact, the TME cells are a double-edged sword as they play both pro- and anti-tumor roles. The interaction of the tumor-infiltrating cells (TIC) with the cancer cells induces the polarization of the TIC, exhibiting an antagonist phenotype. This polarization is controlled by a plethora of interconnected pro- and anti-oncogenic signaling pathways. The complexity of this interaction and the dual function of these different actors contribute to the failure of CRC control. Thus, a better understanding of such mechanisms is of great interest and provides new opportunities for the development of personalized and efficient therapies for CRC. In this review, we summarize the signaling pathways linked to CRC and their implication in the development or inhibition of the tumor initiation and progression. In the second part, we enlist the major components of the TME and discuss the complexity of their cells functions.

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.

Prognostic effects of the gastric mucosal microbiota in gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors with a high incidence and mortality. Microbiota play a significant role in human health and disease. We aimed to investigate the prognostic value of the gastric microbiota in different stomach microhabitats. We used our previously published 16S rRNA gene sequence data. We retrospectively enrolled a cohort of 132 patients with GC with complete prognostic information and selected 78 normal tissues, 49 peritumoral tissues, and 112 tumoral tissues for microbiota analysis. Patients with different prognoses showed different gastric microbiota compositions and diversity. The association network of the abundant gastric microbiota was more complicated in patients with poor prognoses. In the peritumoral microhabitat of patients with good prognoses, Helicobacter was significantly increased, whereas Halomonas and Shewanella were significantly decreased relative to that in the peritumoral microhabitat of patients with poor prognoses. PiCRUSt analysis revealed that the peritumoral microbiota had more different Kyoto Encyclopedia of Genes and Genomes pathways than did the tumoral and normal microbiota. This study evaluated the long-term prognostic value of the gastric mucosal microbiota in patients with GC. These findings suggested that the characteristic alterations of the gastric mucosal microbiota may be markers for clinical outcomes in these patients.

Targeting regulatory T cells in gastric cancer: Pathogenesis, immunotherapy, and prognosis

Gastric cancer (GC) remains one of the most common malignancies worldwide. Despite immune-checkpoint inhibitors (ICIs) has revolutionized cancer treatment and obtained durable clinical responses, only a fraction of GC patients benefit from it. As an important component of T cells, regulatory T cells (Tregs) play a vital role in the pathogenesis of GC, keep a core balance between immune suppression and autoimmunity, and function as predictive biomarkers for prognosis of GC patients. In this review, we discuss the role of Tregs in the pathogenesis of GC, and targeting Tregs via influencing their transcription factor, migration, co-stimulatory receptors, immune checkpoints, and cytokines. We also focus on the currently important findings of Tregs metabolism including amino acid, fatty acid, and lactic acid metabolism of GC. The emerging role of microbiome and clinical combined therapy in modulating Tregs in GC treatment is also summarized. Meanwhile, this review recapitulates a novel regulator, magnesium, is involved in mediating Tregs in GC. These research advances on Treg-related strategies provide new insights and challenges for GC progression, treatment, and prognosis. And we hope our review can stimulate further discovery and implication of mediators and pathways targeting Tregs.

The Influence of the microbiome on the innate immune microenvironment of solid tumors

Cancer remains a leading cause of death despite many advances in medical and surgical therapy. In recent decades, the investigation for novel therapeutic strategies with greater efficacy and reduced side effects has led to a deeper understanding of the relationship between the microbiome and the immune system in the context of cancer. The ability of the immune system to detect and kill cancer is now recognized to be greatly influenced by the microbial ecosystem of the host. While most of these studies, as well as currently used immunotherapeutics, focus on the adaptive immune system, this minimizes the impact of the innate immune system in cancer surveillance and its regulation by the host microbiome. In this review, known influences of the microbiome on the innate immune cells in the tumor microenvironment will be discussed in the context of individual innate immune cells. Current and needed areas of investigation will highlight the field and its potential impact in the clinical treatment of solid malignancies.

A cell cycle-related lncRNA signature predicts the progression-free interval in papillary thyroid carcinoma

The cell cycle plays a vital role in tumorigenesis and progression. Long non-coding RNAs (lncRNAs) are key regulators of cell cycle processes. Therefore, understanding cell cycle-related lncRNAs (CCR-lncRNAs) is crucial for determining the prognosis of papillary thyroid carcinoma (PTC). RNA-seq and clinical data of PTC were acquired from The Cancer Genome Atlas, and CCR-lncRNAs were selected based on Pearson's correlation coefficients. According to univariate Cox regression, least absolute shrinkage and selection operator (LASSO), and multivariate Cox regression analyses, a five-CCR-lncRNA signature (FOXD2-AS1, LOC100507156, BSG-AS1, EGOT, and TMEM105) was established to predict the progression-free interval (PFI) in PTC. Kaplan-Meier survival, time-dependent receiver operating characteristic curve, and multivariate Cox regression analyses proved that the signature had a reliable prognostic capability. A nomogram consisting of the risk signature and clinical characteristics was constructed that effectively predicted the PFI in PTC. Functional enrichment analyses indicted that the signature was involved in cell cycle- and immune-related pathways. Furthermore, we also analyzed the correlation between the signature and immune cell infiltration. Finally, we verified the differential expression of CCR-lncRNAs in vitro using quantitative real-time polymerase chain reaction. Overall, the newly developed prognostic risk signature based on five CCR-lncRNAs may become a marker for predicting the PFI in PTC.

Tumor microbiome - an integral part of the tumor microenvironment

The tumor microenvironment (TME) plays a significant role in tumor progression and cancer cell survival. Besides malignant cells and non-malignant components, including immune cells, elements of the extracellular matrix, stromal cells, and endothelial cells, the tumor microbiome is considered to be an integral part of the TME. Mounting evidence from preclinical and clinical studies evaluated the presence of tumor type-specific intratumoral bacteria. Differences in microbiome composition between cancerous tissues and benign controls suggest the importance of the microbiome-based approach. Complex host-microbiota crosstalk within the TME affects tumor cell biology via the regulation of oncogenic pathways, immune response modulation, and interaction with microbiota-derived metabolites. Significantly, the involvement of tumor-associated microbiota in cancer drug metabolism highlights the therapeutic implications. This review aims to summarize current knowledge about the emerging role of tumor microbiome in various types of solid malignancies. The clinical utility of tumor microbiome in cancer progression and treatment is also discussed. Moreover, we provide an overview of clinical trials evaluating the role of tumor microbiome in cancer patients. The research focusing on the communication between the gut and tumor microbiomes may bring new opportunities for targeting the microbiome to increase the efficacy of cancer treatment and improve patient outcomes.

Prospect of bacteria for tumor diagnosis and treatment

In recent decades, the comprehensive cancer treatments including surgery, chemotherapy, and radiotherapy have improved the overall survival rate and quality of life of many cancer patients. However, we are still facing many difficult problems in the cancer treatment, such as unpredictable side effects, high recurrence rate, and poor curative effect. Therefore, the better intervention strategies are needed in this field. In recent years, the role and importance of microbiota in a variety of diseases were focused on as a hot research topic, and the role of some intracellular bacteria of cancer cells in carcinogenesis has recently been discovered. The impact of bacteria on cancer is not limited to their contribution to tumorigenesis, but the overall susceptibility of bacteria to subsequent tumor progression, the development of concurrent infections, and the response to anti-cancer therapy have also been found to be affected. Concerns about the contribution of bacteria in the anti-cancer response have inspired researchers to develop bacteria-based anti-cancer treatments. In this paper, we reviewed the main roles of bacteria in the occurrence and development of tumors, and summarized the mechanism of bacteria in the occurrence, development, and clinical anti-tumor treatment of tumors, providing new insights for the in-depth study of the role of bacteria in tumor diagnosis and treatment. This review aims to provide a new perspective for the development of new technologies based on bacteria to enhance anti-tumor immunotherapy.

Genetic mutation and tumor microbiota determine heterogenicity of tumor immune signature: Evidence from gastric and colorectal synchronous cancers

Both colorectal and gastric cancer are lethal solid-tumor malignancies, leading to the majority of cancer-associated deaths worldwide. Although colorectal cancer (CRC) and gastric cancer (GC) share many similarities, the prognosis and drug response of CRC and GC are different. However, determinants for such differences have not been elucidated. To avoid genetic background variance, we performed multi-omics analysis, including single-cell RNA sequencing, whole-exome sequencing, and microbiome sequencing, to dissect the tumor immune signature of synchronous primary tumors of GC and CRC. We found that cellular components of juxta-tumoral sites were quite similar, while tumoral cellular components were specific to the tumoral sites. In addition, the mutational landscape and microbiome contributed to the distinct TME cellular components. Overall, we found that different prognoses and drug responses of GC and CRC were mainly due to the distinct TME determined by mutational landscape and microbiome components.

Comparative analysis of the lung microbiota in patients with respiratory infections, tuberculosis, and lung cancer: A preliminary study

Recent evidence suggests that lung microbiota can be recognized as one of the ecological determinants of various respiratory diseases. However, alterations in the lung microbiota and associated lung immunity in these respiratory diseases remain unclear. To compare the lung microbiota and lung immune profiles in common respiratory diseases, a total of 78 patients were enrolled in the present study, including 21 patients with primary pulmonary tuberculosis (PTB), eight patients with newly diagnosed lung cancer (LC), and 49 patients with community-acquired pneumonia (CAP). Bronchoalveolar lavage fluid (BALF) was collected for microbiota and cytokine analyses. With MiSeq sequencing system, increased bacterial alpha-diversity and richness were observed in patients with LC than in those with PTB and CAP. Linear discriminant analysis effect size revealed that CAP-associated pulmonary microbiota were significantly different between the PTB and LC groups. More key functionally different genera were found in the PTB and LC groups than in the CAP group. The interaction network revealed stronger positive and negative correlations among these genera in the LC group than in the other two groups. However, increased BALF cytokine profiles were observed in the PTB group than in the other two groups, while BALF cytokines were correlated with key functional bacteria. This comparative study provides evidence for the associations among altered lung microbiota, BALF inflammation, and different respiratory disorders, which provides insight into the possible roles and mechanisms of pulmonary microbiota in the progression of respiratory disorders.

Tumor microenvironment-mediated immune tolerance in development and treatment of gastric cancer

Tumor microenvironment is the general term for all non-cancer components and their metabolites in tumor tissue. These components include the extracellular matrix, fibroblasts, immune cells, and endothelial cells. In the early stages of tumors, the tumor microenvironment has a tumor suppressor function. As the tumor progresses, tumor immune tolerance is induced under the action of various factors, such that the tumor suppressor microenvironment is continuously transformed into a tumor-promoting microenvironment, which promotes tumor immune escape. Eventually, tumor cells manifest the characteristics of malignant proliferation, invasion, metastasis, and drug resistance. In recent years, stress effects of the extracellular matrix, metabolic and phenotypic changes of innate immune cells (such as neutrophils, mast cells), and adaptive immune cells in the tumor microenvironment have been revealed to mediate the emerging mechanisms of immune tolerance, providing us with a large number of emerging therapeutic targets to relieve tumor immune tolerance. Gastric cancer is one of the most common digestive tract malignancies worldwide, whose mortality rate remains high. According to latest guidelines, the first-line chemotherapy of advanced gastric cancer is the traditional platinum and fluorouracil therapy, while immunotherapy for gastric cancer is extremely limited, including only Human epidermal growth factor receptor 2 (HER-2) and programmed death ligand 1 (PD-L1) targeted drugs, whose benefits are limited. Clinical experiments confirmed that cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), vascular endothelial growth factor receptor (VEGFR) and other targeted drugs alone or in combination with other drugs have limited efficacy in patients with advanced gastric cancer, far less than in lung cancer, colon cancer, and other tumors. The failure of immunotherapy is mainly related to the induction of immune tolerance in the tumor microenvironment of gastric cancer. Therefore, solving the immune tolerance of tumors is key to the success of gastric cancer immunotherapy. In this study, we summarize the latest mechanisms of various components of the tumor microenvironment in gastric cancer for inducing immune tolerance and promoting the formation of the malignant phenotype of gastric cancer, as well as the research progress of targeting the tumor microenvironment to overcome immune tolerance in the treatment of gastric cancer.

Investigation of the immune escape mechanism of Treponema pallidum

BACKGROUND

Syphilis is a chronic sexually transmitted disease caused by Treponema pallidum subspecies pallidum (T. pallidum), which is a public health problem that seriously affects human health worldwide. T. pallidum is characterized by early transmission and immune escape and is therefore termed an "invisible pathogen".

METHODS

This review systematically summarizes the host's innate and adaptive immune responses to T. pallidum infection as well as the escape mechanisms of T. pallidum.

PURPOSE

To lay the foundation for assessing the pathogenic mechanism and the systematic prevention and treatment of syphilis.

CONCLUSION

The immune escape mechanism of T. pallidum plays an important role in its survival. Exploring the occurrence and development of these mechanisms has laid the foundation for the development of syphilis vaccine.

FOXP3+ regulatory T cells and the immune escape in solid tumours

FOXP3+ regulatory T (Treg) cells play critical roles in establishing the immunosuppressive tumour microenvironment, which is achieved and dynamically maintained with the contribution of various stromal and immune cell subsets. However, the dynamics of non-lymphoid FOXP3+ Treg cells and the mutual regulation of Treg cells and other cell types in solid tumour microenvironment remains largely unclear. In this review, we summarize the latest findings on the dynamic connections and reciprocal regulations of non-lymphoid Treg cell subsets in accordance with well-established and new emerging hallmarks of cancer, especially on the immune escape of tumour cells in solid tumours. Our comprehension of the interplay between FOXP3+ Treg cells and key hallmarks of cancer may provide new insights into the development of next-generation engineered T cell-based immune treatments for solid tumours.

Relationships among microbiota, gastric cancer, and immunotherapy

Currently, conventional neoadjuvant therapy or postoperative adjuvant therapy, such as chemotherapy and radiation therapy, can only bring limited survival benefits to gastric cancer (GC). Median survival after palliative chemotherapy is also low, at about 8–10 months. Immunotargeting is a new option for the treatment of GC, but has not been widely replicated. The highly immunosuppressed tumor microenvironment (TME) discounts the efficacy of immunotherapy for GC. Therefore, new strategies are needed to enhance the immune response of the TME. This paper reviewed the relationship between microorganisms and GC, potential links between microorganisms and immunotherapy and research of microorganisms combined immunotherapy.

Bile reflux alters the profile of the gastric mucosa microbiota

Background

Bile reflux can cause inflammation, gastric mucosa atrophy, and diseases such as stomach cancer. Alkaline bile flowing back into the stomach affects the intragastric environment and can alter the gastric bacterial community. We sought to identify the characteristics of the stomach mucosal microbiota in patients with bile reflux.

Methods

Gastric mucosal samples were collected from 52 and 40 chronic gastritis patients with and without bile reflux, respectively. The bacterial profile was determined using 16S rRNA gene analysis.

Results

In the absence of H. pylori infection, the richness (based on the Sobs and Chao1 indices; P <0.05) and diversity (based on Shannon indices; P <0.05) of gastric mucosa microbiota were higher in patients with bile reflux patients than in those without. There was a marked difference in the microbiota structure between patients with and without bile reflux (ANOSIM, R=0.058, P=0.011). While the genera, Comamonas, Halomonas, Bradymonas, Pseudomonas, Marinobacter, Arthrobacter, and Shewanella were enriched in patients with bile reflux, the genera, Haemophilus, Porphyromonas, and Subdoligranulum, were enriched in those without bile reflux.

Conclusion

Our results demonstrate that bile reflux significantly alters the composition of the gastric microbiota.

Incorporating Immunotherapy in the Management of Gastric Cancer: Molecular and Clinical Implications

Simple Summary

Gastric cancer is one of the most common malignant tumours worldwide, with the fifth and third highest morbidity and mortality, respectively, of all cancers. Survival is limited, as most of the patients are diagnosed at an advanced stage, and are not suitable for surgery with a curative intent. Chemotherapy has only modestly improved patients’ outcomes and is mainly given with a palliative intent. Immunotherapy has improved overall survival of patients with gastric cancer, and has thus become a new standard of care in clinic. In this review we discuss the strong molecular rationale for the administration of immunotherapy in this disease and analyse the clinical data supporting its use.

Abstract

Gastric cancer has a median survival of 11 months, and this poor prognosis has not improved over the last 30 years. Recent pre-clinical data suggest that there is high tumour-related neoantigen expression in gastric cancer cells, suggesting that a clinical strategy that enhances the host’s immune system against cancer cells may be a successful approach to improve clinical outcomes. Additionally, there has been an increasing amount of translational evidence highlighting the relevance of PD-L1 expression in gastric cancer cells, indicating that PD-1/PD-L1 inhibitors may be useful. Several molecular subgroups of gastric cancer have been identified to respond with excellent outcomes to immunotherapy, including microsatellite instable tumours, tumours bearing a high tumour mutational burden, and tumours related to a chronic EBV infection. In gastric cancer, immunotherapy has produced durable responses in chemo-refractory patients; however, most recently there has been a lot of enthusiasm as several large-scale clinical trials highlight the improved survival noted from the incorporation of immunotherapy in the first line setting for advanced gastric cancer. Our review aims to discuss current pre-clinical and clinical data supporting the innovative role of immunotherapy in gastric cancer.

Changes in fecal microbiota composition and the cytokine expression profile in school-aged children with depression: A case-control study

Depression in childhood negatively affects the growth and development, school performance, and peer or family relationships of affected children, and may even lead to suicide. Despite this, its etiology and pathophysiology remain largely unknown. Increasing evidence supports that gut microbiota plays a vital role in the development of childhood depression. However, little is known about the underlying mechanisms, as most clinical studies investigating the link between gut microbiota and depression have been undertaken in adult cohorts. In present study, a total of 140 school-aged children (6–12 years) were enrolled, including 92 with depression (male/female: 42/50) and 48 healthy controls (male/female: 22/26) from Lishui, Zhejiang, China. Illumina sequencing of the V3–V4 region of the 16S rRNA gene was used to investigate gut microbiota profiles while Bio-Plex Pro Human Cytokine 27-plex Panel was employed to explore host immune response. We found that, compared with healthy controls, children with depression had greater bacterial richness and altered β-diversity. Pro-inflammatory genera such as Streptococcus were enriched in the depression group, whereas anti-inflammatory genera such as Faecalibacterium were reduced, as determined by linear discriminant analysis effect size. These changes corresponded to altered bacterial functions, especially the production of immunomodulatory metabolites. We also identified the presence of a complex inflammatory condition in children with depression, characterized by increased levels of pro-inflammatory cytokines such as IL-17 and decreased levels of anti-inflammatory cytokines such as IFN-γ. Correlation analysis demonstrated that the differential cytokine abundance was closely linked to changes in gut microbiota of children with depression. In summary, key functional genera, such as Streptococcus and Faecalibacterium, alone or in combination, could serve as novel and powerful non-invasive biomarkers to distinguish between children with depression from healthy ones. This study was the first to demonstrate that, in Chinese children with depression, gut microbiota homeostasis is disrupted, concomitant with the activation of a complex pro-inflammatory response. These findings suggest that gut microbiota might play an important role in the pathogenesis of depression in school-aged children, while key functional bacteria in gut may serve as novel targets for non-invasive diagnosis and patient-tailored early precise intervention in children with depression.

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.

Influences of Helicobacter pylori infection on diversity, heterogeneity, and composition of human gastric microbiomes across stages of gastric cancer development

BACKGROUND

About a half of the world's population is infected with Helicobacter pylori (H. pylori), but only 1%-3% of them develop gastric cancer. As a primary risk factor for gastric cancer, the relationship between H. pylori infection and gastric microbiome has been a focus in recent years.

MATERIALS AND METHODS

We reanalyze 11 human gastric microbiome datasets with or without H. pylori, covering the healthy control (HC) and four disease stages (chronic gastritis (CG), atrophic gastritis (AG), intestinal metaplasia (IM), and gastric cancer (GC)) of gastric cancer development to quantitatively compare the influences of the H. pylori infection and disease stages on the diversity, heterogeneity, and composition of gastric microbiome. Four medical ecology approaches including (i) diversity analysis with Hill numbers, (ii) heterogeneity analysis with Taylor's power law extensions (TPLE), (iii) diversity scaling analysis with diversity-area relationship (DAR) model, and (iv) shared species analysis were applied to fulfill the data reanalysis.

RESULTS

(i) The influences of H. pylori infection on the species diversity, spatial heterogeneity, and potential diversity of gastric microbiome seem to be more prevalent than the influences of disease stages during gastric cancer development. (ii) The influences of H. pyloriinfection on diversity, heterogeneity, and composition of gastric microbiomes in HC, CG, IM, and GC stages appear more prevalent than those in AG stage.

CONCLUSION

Our study confirmed the impact of H. pylori infection on human gastric microbiomes: The influences of H. pylori infection on the diversity, heterogeneity, and composition of gastric microbiomes appear to be disease-stage dependent.

Fecal Dysbiosis and Immune Dysfunction in Chinese Elderly Patients With Schizophrenia: An Observational Study

Schizophrenia (SZ) is a severe neuropsychiatric disorder with largely unknown etiology and pathogenesis. Mounting preclinical and clinical evidence suggests that the gut microbiome is a vital player in SZ. However, the gut microbiota characteristics and its host response in elderly SZ patients are still not well understood. A total of 161 samples was collected, including 90 samples from elderly SZ patients and 71 samples from healthy controls. We explored the gut microbiota profiles targeting the V3–V4 region of the 16S rRNA gene by MiSeq sequencing, and to analyze their associations with host immune response. Our data found that bacterial β-diversity analyses could divide the SZ patients and healthy controls into two different clusters. The Linear discriminant analysis Effect Size (LEfSe) identified the compositional changes in SZ-associated bacteria, including Faecalibacterium, Roseburia, Actinomyces, Butyricicoccus, Prevotella and so on. In addition, the levels of pro-inflammatory cytokines such as IL-1β were greatly increased in SZ patients while the levels of anti-inflammatory cytokines such as IFN-γ were markedly decreased. Correlation analysis suggested that these bacteria contributed to immune disturbances in the host that could be used as non-invasive biomarkers to distinguish the SZ patients from healthy controls. Moreover, several predicted functional modules, including increased lipopolysaccharide biosynthesis, folate biosynthesis, lipoic acid metabolism, and decreased bile acid biosynthesis, fatty acid biosynthesis in SZ-associated microbiota, could be utilized by the bacteria to produce immunomodulatory metabolites. This study, for the first time, demonstrated the structural and functional dysbiosis of the fecal microbiota in Chinese elderly SZ patients, suggesting the potential for using gut key functional bacteria for the early, non-invasive diagnosis of SZ, personalized treatment, and the development of tailor-made probiotics designed for Chinese elderly SZ patients.

Bacteria and tumor: Understanding the roles of bacteria in tumor genesis and immunology

In the past, tumor and microbial infection were commonly regarded as independent diseases with few interrelations. The discovery of bacteria in tumor tissue changed the knowledge of bacteria-tumor relationship. Recently, more and more findings have demonstrated the significant effects of bacteria on the genesis, development and metastasis of tumor. Particularly, the influence of bacteria on tumor immunity is of great interest. Bacteria can inhibit the function of immune system through multiple mechanisms. On the other hand, some bacteria can also enhance the immune response and inhibit tumor progression. Understanding the bacteria-tumor interactions is of great importance for developing novel anticancer approaches. Herein, we aim to provide a comprehensive understanding of the tumor/tumor immunology, the biogenesis of bacteria in tumor and the relation of tumorigenesis with bacteria. In addition, the roles of bacteria in tumor immunology and the potential approaches to use bacteria for cancer therapy are discussed.

Interaction between Bacteria and the Immune System for Cancer Immunotherapy: The α-GalCer Alliance

Non-conventional T cells, such as γδ T and invariant natural killer T (iNKT) cells, are emerging players in fighting cancer. Alpha-galactosylceramide (α-GalCer) is used as an exogenous ligand to activate iNKT cells. Human cells don’t have a direct pathway producing α-GalCer, which, however, can be produced by bacteria. We searched the literature for bacteria strains that are able to produce α-GalCer and used available sequencing data to analyze their presence in human tumor tissues and their association with survival. The modulatory effect of antibiotics on the concentration of α-GalCer was analyzed in mice. The human gut bacteria Bacteroides fragilis, Bacteroides vulgatus, and Prevotella copri produce α-GalCer structures that are able to activate iNKT cells. In mice, α-GalCer was depleted upon treatment with vancomycin. The three species were detected in colon adenocarcinoma (COAD) and rectum adenocarcinoma tissues, and Prevotella copri was also detected in bone tumors and glioblastoma tissues. Bacteroides vulgatus in COAD tissues correlated with better survival. In conclusion, α-GalCer-producing bacteria are part of the human gut microbiome and can infiltrate tumor tissues. These results suggest a new mechanism of interaction between bacteria and immune cells: α-GalCer produced by bacteria may activate non-conventional T cells in tumor tissues, where they can exert a direct or indirect anti-tumor activity.

Advances in Human Dendritic Cell-Based Immunotherapy Against Gastrointestinal Cancer

Dendritic cells (DCs), the strongest antigen-presenting cells, are a focus for orchestrating the immune system in the fight against cancer. Basic scientific investigations elucidating the cellular biology of the DCs have resulted in new strategies in this fight, including cancer vaccinology, combination therapy, and adoptive cellular therapy. Although immunotherapy is currently becoming an unprecedented bench-to-bedside success, the overall response rate to the current immunotherapy in patients with gastrointestinal (GI) cancers is pretty low. Here, we have carried out a literature search of the studies of DCs in the treatment of GI cancer patients. We provide the advances in DC-based immunotherapy and highlight the clinical trials that indicate the therapeutic efficacies and toxicities related with each vaccine. Moreover, we also offer the yet-to-be-addressed questions about DC-based immunotherapy. This study focuses predominantly on the data derived from human studies to help understand the involvement of DCs in patients with GI cancers.

Targeting the gut and tumor microbiota in cancer

Microorganisms within the gut and other niches may contribute to carcinogenesis, as well as shaping cancer immunosurveillance and response to immunotherapy. Our understanding of the complex relationship between different host-intrinsic microorganisms, as well as the multifaceted mechanisms by which they influence health and disease, has grown tremendously-hastening development of novel therapeutic strategies that target the microbiota to improve treatment outcomes in cancer. Accordingly, the evaluation of a patient's microbial composition and function and its subsequent targeted modulation represent key elements of future multidisciplinary and precision-medicine approaches. In this Review, we outline the current state of research toward harnessing the microbiome to better prevent and treat cancer.

Impacts and mechanisms of metabolic reprogramming of tumor microenvironment for immunotherapy in gastric cancer

Metabolic disorders and abnormal immune function changes occur in tumor tissues and cells to varying degrees. There is increasing evidence that reprogrammed energy metabolism contributes to the development of tumor suppressive immune microenvironment and influences the course of gastric cancer (GC). Current studies have found that tumor microenvironment (TME) also has important clinicopathological significance in predicting prognosis and therapeutic efficacy. Novel approaches targeting TME therapy, such as immune checkpoint blockade (ICB), metabolic inhibitors and key enzymes of immune metabolism, have been involved in the treatment of GC. However, the interaction between GC cells metabolism and immune metabolism and how to make better use of these immunotherapy methods in the complex TME in GC are still being explored. Here, we discuss how metabolic reprogramming of GC cells and immune cells involved in GC immune responses modulate anti-tumor immune responses, as well as the effects of gastrointestinal flora in TME and GC. It is also proposed how to enhance anti-tumor immune response by understanding the targeted metabolism of these metabolic reprogramming to provide direction for the treatment and prognosis of GC.

Identification of tissue-specific microbial profile of esophageal squamous cell carcinoma by full-length 16S rDNA sequencing

It was previously believed that the microbial community in the esophagus was relatively stable, but it has been reported that different esophageal diseases have different microbial community characteristics. In this study, we recruited patients with esophageal squamous cell carcinoma (ESCC) and collected 51 pairs of tumor and adjacent non-tumor tissues for full-length 16S rDNAsequencing and qPCR to compare the differences in microbial community structure. The results of sequencing in 19 pairs of tissues showed that Proteobacteria, Firmicutes, Bacteroidetes, Deinococcus-Thermus, and Actinobacteria were the main bacteria in tumor and adjacent non-tumor tissues. At the genus level, the bacteria with the highest relative proportion in tumor and adjacent non-tumor tissues were Streptococcus and Labrys, respectively. At the same time, it was observed that the complexity of microbial interactions in tumor tissues was weaker than that of adjacent non-tumor tissues. The results also found that the relative abundance of 24 taxa was statistically different between tumor and adjacent non-tumor tissues. The findings of qPCR in 32 pairs of tissues further evidence that the relative proportions of Blautia, Treponema, Lactobacillus murinus, Peptoanaerobacter stomatis, and Fusobacteria periodonticum were statistically different in tumor and adjacent non-tumor tissues. The findings of PIRCUSt2 indicated the lipopolysaccharide biosynthesis and biotin metabolism in the microbiome of cancer tissues are more significant. This study supplements the existing information on the structure, function, and interaction of microorganisms in the esophagus in situ and provides a direction for the further exploration of the relationship between esophageal in situ microorganisms and esophageal squamous cell carcinoma. KEY POINTS: • The structure of the microbial community in esophageal cancer tissue and adjacent non-tumor tissues at the phylum level is similar • Streptococcus and Labrys are the most important bacteria in esophageal tumor tissues and adjacent non-tumor tissues, respectively • Microbial interactions in tumor tissues are stronger than in adjacent non-tumor tissues.

Roles of Plasmacytoid Dendritic Cells in Gastric Cancer

Gastric cancer (GC) is the fifth most common neoplasm and the third most deadly cancer in humans worldwide. Helicobacter pylori infection is the most important causative factor of gastric carcinogenesis, and activates host innate and adaptive immune responses. As key constituents of the tumor immune microenvironment, plasmacytoid dendritic cells (pDCs) are increasingly attracting attention owing to their potential roles in immunosuppression. We recently reported that pDCs have vital roles in the development of immunosuppression in GC. Clarifying the contribution of pDCs to the development and progression of GC may lead to improvements in cancer therapy. In this review, we summarize current knowledge regarding immune modulation in GC, especially the roles of pDCs in GC carcinogenesis and treatment strategies.

ELP6 and PLIN5 Mutations Were Probably Prognostic Biomarkers for Patients With Gastric Cancer

Purpose

Gastric cancer (GC) is the fifth leading cancer around world. And prognosis of patients with GC is still undesirable. Our study aimed to explore potential prognostic biomarkers for patients with GC.

Methods

The clinical samples were collected from the Qinghai University Affiliated Hospital, which were subjected to the whole exome sequencing (WES). The other GC-related data were obtained from The Cancer Genome Atlas (TCGA) database. Cross analyses were done to determine the candidate genes. And the final mutated genes were determined by survival analyses, univariate and multivariate Cox regression analyses. CIBERSORT and GSEA were used for immune cell infiltration analysis and functional enrichment, respectively.

Results

After cross analyses, 160 candidate-mutated genes were identified. And mutated ELP6 and PLIN5 were significantly independently correlated with the overall survival (OS) of patients with GC. Patients with GC with ELP6 and PLIN5 mutations had worse and better prognosis, respectively. Totally 5 types of immune cells were significantly differentially infiltrated in wild-type and mutated ELP6 and PLIN5 GC samples. In mutated ELP6 and PLIN5 GC samples, totally 7 and 11 pathways were significantly enriched, respectively.

Conclusions

The ELP6 and PLIN5 mutations were probably prognostic biomarkers for patients with GC.

Host miRNAs-microbiota interactions in gastric cancer

It is widely acknowledged that gastric cancer seriously affects the quality of life and survival of patients. The correlation between the microbiota and gastric cancer has attracted extensive attention in recent years, nonetheless the specific mechanism of its impact on gastric cancer remain largely unclear. Recent studies have shown that in addition to its role in the host’s inflammatory and immune response, the microbiota can also affect the occurrence and development of gastric cancer by affecting the expression of miRNAs. This paper brings together all currently available data on miRNAs, microbiota and gastric cancer, and preliminarily describes the relationship among them.