Role of plasmacytoid dendritic cells and inducible costimulator-positive regulatory T cells in the immunosuppression microenvironment of gastric cancer

Advances in the study of the role of gastric microbiota in the progression of gastric cancer

Gastric cancer (GC) is a common malignant tumor and the third most common cancer in China in terms of mortality. Stomach microorganisms play complex roles in the development of GC. The carcinogenic mechanism of Helicobacter pylori has been elucidated, and there is much evidence that other microorganisms in the gastric mucosa are also heavily involved in the disease progression of this cancer. However, their carcinogenic mechanisms have not yet been fully elucidated. The microbial compositions associated with the normal stomach, precancerous lesions, and GC are distinctly different and have a complex evolutionary mechanism. The dysregulation of gastric microbiota may play a key role in the oncogenic process from precancerous lesions to malignant gastric tumors. In this review, we explore the potential translational and clinical implications of intragastric microbes in the diagnosis, prognosis, and treatment of GC. Finally, we summarize the research dilemmas and solutions concerning intragastric microbes, emphasizing that they should be at the forefront of strategies for GC prevention and treatment.

A literature review of recent advances in gastric cancer treatment: exploring the cross-talk between targeted therapies

BACKGROUND

Gastric cancer (GC) ranks fourth in global mortality rates and fifth in prevalence, making it one of the most common cancers worldwide. Recent clinical studies have highlighted the potential of immunotherapies as a promising approach to treating GC. This study aims to shed light on the most impactful therapeutic strategies in the context of GC immunotherapy, highlighting both established and emerging approaches.

MAIN BODY

This review examines over 160 clinical studies conducted globally, focusing on the effectiveness of various immunotherapy modalities, including cancer vaccines, adoptive cell therapy, immune checkpoint inhibitors (ICIs), and monoclonal antibodies (mAbs). A comprehensive search of peer-reviewed literature was performed using databases such as Web of Science, PubMed, and Scopus. The selection criteria included peer-reviewed articles published primarily within the last 10 years, with a focus on studies that provided insights into targeted therapies and their mechanisms of action, clinical efficacy, and safety profiles. The findings indicate that these immunotherapy strategies can enhance treatment outcomes for GC, aligning with current treatment guidelines. ICIs like pembrolizumab and nivolumab have shown significant survival benefits in specific GC subgroups. Cancer vaccines and CAR-T cell therapies demonstrate potential, while mAbs targeting HER2 and VEGFR pathways enhance outcomes in combination regimens. We discuss the latest advancements and challenges in targeted therapy and immunotherapy for GC. Given the evolving nature of this field, this research emphasizes significant evidence-based therapies and those currently under evaluation rather than providing an exhaustive overview. Challenges include resistance mechanisms, immunosuppressive tumor environments, and inconsistent results from combination therapies. Biomarker-driven approaches and further research into emerging modalities like CAR-T cells and cancer vaccines are critical for optimizing treatments.

CONCLUSIONS

Immunotherapy is reshaping GC management by improving survival and quality of life. Ongoing research and clinical evaluations are crucial for refining personalized and effective therapies.

Molecular Mechanism for Malignant Progression of Gastric Cancer Within the Tumor Microenvironment

Gastric cancer (GC) is one of the most common cancers worldwide. Most patients are diagnosed at the progressive stage of GC, and progress in the development of effective anti-GC drugs has been insufficient. The tumor microenvironment (TME) regulates various functions of tumor cells, and interactions between the cellular and molecular components of the TME-e.g., inflammatory cells, fibroblasts, vasculature cells, and innate and adaptive immune cells-promote the aggressiveness of cancer cells and dissemination to distant organs. This review summarizes the roles of various TME cells and molecules in regulating the malignant progression and metastasis of GC. We also address the important roles of signaling pathways in mediating the interaction between cancer cells and the different components of the GC TME. Finally, we discuss the implications of these molecular mechanisms for developing novel and effective therapies targeting molecular and cellular components of the GC TME to control the malignant progression of GC.

Dysregulation of systemic immunity and its clinical application in gastric cancer

Immunotherapy has profoundly changed the treatment of gastric cancer, but only a minority of patients benefit from immunotherapy. Therefore, numerous studies have been devoted to clarifying the mechanisms underlying resistance to immunotherapy or developing biomarkers for patient stratification. However, previous studies have focused mainly on the tumor microenvironment. Systemic immune perturbations have long been observed in patients with gastric cancer, and the involvement of the peripheral immune system in effective anticancer responses has attracted much attention in recent years. Therefore, understanding the distinct types of systemic immune organization in gastric cancer will aid personalized treatment designed to pair with traditional therapies to alleviate their detrimental effects on systemic immunity or to directly activate the anticancer response of systemic immunity. Herein, this review aims to comprehensively summarize systemic immunity in gastric cancer, including perturbations in systemic immunity induced by cancer and traditional therapies, and the potential clinical applications of systemic immunity in the detection, prediction, prognosis and therapy of gastric cancer.

Plasmacytoid dendritic cells at the forefront of anti-cancer immunity: rewiring strategies for tumor microenvironment remodeling

Plasmacytoid dendritic cells (pDCs) are multifaceted immune cells executing various innate immunological functions. Their first line of defence consists in type I interferons (I-IFN) production upon nucleic acids sensing through endosomal Toll-like receptor (TLR) 7- and 9-dependent signalling pathways. Type I IFNs are a class of proinflammatory cytokines that have context-dependent functions on cancer immunosurveillance and immunoediting. In the last few years, different studies have reported that pDCs are also able to sense cytosolic DNA through cGAS-STING (stimulator of interferon genes) pathway eliciting a potent I-IFN production independently of TLR7/9. Human pDCs are also endowed with direct effector functions via the upregulation of TRAIL and production of granzyme B, the latter modulated by cytokines abundant in cancer tissues. pDCs have been detected in a wide variety of human malignant neoplasms, including virus-associated cancers, recruited by chemotactic stimuli. Although the role of pDCs in cancer immune surveillance is still uncompletely understood, their spontaneous activation has been rarely documented; moreover, their presence in the tumor microenvironment (TME) has been associated with a tolerogenic phenotype induced by immunosuppressive cytokines or oncometabolites. Currently tested treatment options can lead to pDCs activation and disruption of the immunosuppressive TME, providing a relevant clinical benefit. On the contrary, the antibody-drug conjugates targeting BDCA-2 on immunosuppressive tumor-associated pDCs (TA-pDCs) could be proposed as novel immunomodulatory therapies to achieve disease control in patients with advance stage hematologic malignancies or solid tumors. This Review integrate recent evidence on the biology of pDCs and their pharmacological modulation, suggesting their relevant role at the forefront of cancer immunity.

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.

Inhibitory receptors of plasmacytoid dendritic cells as possible targets for checkpoint blockade in cancer

Plasmacytoid dendritic cells (pDCs) are the major producers of type I interferons (IFNs), which are essential to mount antiviral and antitumoral immune responses. To avoid exaggerated levels of type I IFNs, which pave the way to immune dysregulation and autoimmunity, pDC activation is strictly regulated by a variety of inhibitory receptors (IRs). In tumors, pDCs display an exhausted phenotype and correlate with an unfavorable prognosis, which largely depends on the accumulation of immunosuppressive cytokines and oncometabolites. This review explores the hypothesis that tumor microenvironment may reduce the release of type I IFNs also by a more pDC-specific mechanism, namely the engagement of IRs. Literature shows that many cancer types express de novo, or overexpress, IR ligands (such as BST2, PCNA, CAECAM-1 and modified surface carbohydrates) which often represent a strong predictor of poor outcome and metastasis. In line with this, tumor cells expressing ligands engaging IRs such as BDCA-2, ILT7, TIM3 and CD44 block pDC activation, while this blocking is prevented when IR engagement or signaling is inhibited. Based on this evidence, we propose that the regulation of IFN secretion by IRs may be regarded as an "innate checkpoint", reminiscent of the function of "classical" adaptive immune checkpoints, like PD1 expressed in CD8+ T cells, which restrain autoimmunity and immunopathology but favor chronic infections and tumors. However, we also point out that further work is needed to fully unravel the biology of tumor-associated pDCs, the neat contribution of pDC exhaustion in tumor growth following the engagement of IRs, especially those expressed also by other leukocytes, and their therapeutic potential as targets of combined immune checkpoint blockade in cancer immunotherapy.

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.

Construction of iron metabolism-related prognostic features of gastric cancer based on RNA sequencing and TCGA database

BACKGROUND

Researches have manifested that the disorder of iron metabolism is participated in Gastric cancer (GC), but whether iron metabolism-relevant genes (IMRGs) is related to the survival outcome of GC remain unknown.

METHODS

Eleven tumor as well as nine adjacent normal tissues from GC patients were underwent mRNA sequencing, and the The Cancer Genome Atlas Stomach Cancer (TCGA-STAD) datasets were acquired from the TCGA database. Cox analyses and least absolute shrinkage and selection operator (LASSO) regression were applied to build a IMRGs signature. The relationship between signature genes and the infiltration profiling of 24 immune cells were investigated using single-sample GSEA (ssGSEA). Meanwhile, the potential biological significance, genes that act synergistically with signature genes, and the upstream regulatory targets were predicted. Finally, the abundance of the signature genes were measured via the quantitative real-time PCR (qRT-PCR).

RESULTS

A IMRGs signature was constructed according to the expression and corresponding coefficient of DOHH, P4HA3 and MMP1 (The Schoenfeld individual test showed risk score was not significant with P values = 0.83). The prognostic outcome of patients in the high-risk group was terrible (p < 0.05). Receiver operating characteristic (ROC) curves confirmed that the IMRGs signature presented good efficiency for predicting GC prognosis (AUC > 0.6). The nomogram was performed well for clinical utilize (C-index = 0.60), and the MMP1 expression significantly increased in the cohorts at age > 60 and Stage II-IV (p < 0.05). The positive correlation of P4HA3 and MMP1 expression as well as the negative correlation of DOHH expression with risk score (p < 0.0001) and worse prognosis (p < 0.05) were detected as well. Furthermore, 11 differential immune cells were associated with these signature genes (most p < 0.01). Finally, qRT-PCR revealed that the abundance of DOHH, P4HA3 and MMP1 were high in tumor cases, indicating the complex mechanism between the high expression of DOHH as a protective factor and the high expression of P4HA3 and MMP1 as the risk factors in the development of GC.

CONCLUSION

An iron metabolism-related signature was constructed and has significant values for foretelling the OS of GC.

Diversification and deleterious role of microbiome in gastric cancer

Gut microbiota dictates the fate of several diseases, including cancer. Most gastric cancers (GC) belong to gastric adenocarcinomas (GAC). Helicobacter pylori colonizes the gastric epithelium and is the causative agent of 75% of all stomach malignancies globally. This bacterium has several virulence factors, including cytotoxin-associated gene A (CagA), vacuolating cytotoxin (VacA), and outer membrane proteins (OMPs), all of which have been linked to the development of gastric cancer. In addition, bacteria such as Escherichia coli, Streptococcus, Clostridium, Haemophilus, Veillonella, Staphylococcus, and Lactobacillus play an important role in the development of gastric cancer. Besides, lactic acid bacteria (LAB) such as Bifidobacterium, Lactobacillus, Lactococcus, and Streptococcus were found in greater abundance in GAC patients. To identify potential diagnostic and therapeutic interventions for GC, it is essential to understand the mechanistic role of H. pylori and other bacteria that contribute to gastric carcinogenesis. Furthermore, understanding bacteria-host interactions and bacteria-induced inflammatory pathways in the host is critical for developing treatment targets for gastric cancer.

First-in-class small molecule inhibitors of ICOS/ICOSL interaction as a novel class of immunomodulators

The interaction of the inducible co-stimulator (ICOS) with its ligand (ICOSL) plays key roles in T-cell differentiation and activation of T-cell to B-cell functions. The ICOS/ICOSL pathway is a validated target for T-cell lymphomas induced by the proliferation of T-follicular helper (Tfh) cells. Moreover, the inhibition of ICOS/ICOSL interaction can decrease the enhancement of immunosuppressive regulatory T cells (Tregs) in both hematologic malignancies and solid tumors. However, targeting ICOS/ICOSL interaction is currently restricted to monoclonal antibodies (mAbs) and there are no small molecules in existence that can block ICOS/ICOSL. To fill this gap, we report herein the first time-resolved fluorescence resonance energy transfer (TR-FRET) assay to evaluate the ability of small molecules to inhibit ICOS/ICOSL interaction. Implementation of the developed TR-FRET assay in high-throughput screening (HTS) of a focused chemical library resulted in the identification of AG-120 as a first-in-class inhibitor of ICOS/ICOSL interaction. We further employed docking studies and molecular dynamics (MD) simulations to identify the plausible mechanism of blocking ICOS/ICOSL complex formation by AG-120. Using the structure-activity relationship (SAR) by catalog approach, we identified AG-120-X with an IC50 value of 4.68 ± 0.47 μM in the ICOS/ICOSL TR-FRET assay. Remarkably, AG-120-X revealed a dose-dependent ability to block ICOS/ICOSL interaction in a bioluminescent cellular assay based on co-culturing Jurkat T cells expressing ICOS and CHO-K1 cells expressing ICOSL. This work will pave the way for future drug discovery efforts aiming at the development of small molecule inhibitors of ICOS/ICOSL interaction as potential therapeutics for cancer as well as other diseases.

CCR9-CCL25 mediated plasmacytoid dendritic cell homing and contributed the immunosuppressive microenvironment in gastric cancer

OBJECTIVES

Plasmacytoid dendritic cells (pDCs) play a crucial role in the microenvironment of tumor. Evidences has been shown that chemokine receptor 9 (CCR9) is an important molecule that attracts pDCs homing to the digestive tract and the latter are involved in the formation of digestive tract immune tolerance. The aim of this study was to explore the role of CCR9-CCL25 interaction in pDC-mediated immunosuppression microenvironment of gastric cancer (GC).

MATERIALS AND METHODS

Regulatory T cells (Tregs) and pDCs were detected by immunohistochemistry. CCR9, which expressed on pDC was visualized by immunofluorescence. Western Blot was applied to evaluate the expression of CCL-25. Total pDCs, CCR9+pDCs, CCR9-pDCs, total Tregs, inducible costimulator + (ICOS) Tregs and ICOS-Tregs in peripheral blood and draining lymph nodes were analyzed by flow cytometry. Plasma concentration of the cytokines were measured by enzyme-linked immunosorbent assay RESULTS: Total Tregs, pDCs and CCR9+pDCs were higher in GC tissue. CCL-25 was over-expressed in carcinoma tissue. Peripheral total pDCs, CCR9-pDCs, total Tregs, ICOS+ Tregs, ICOS- Tregs were significantly increased in GC patients. More total pDCs, CCR9+ pDCs, total Tregs, ICOS+ Tregs were found in metastatic lymph nodes. Plasma concentrations of IL-6 and IL-10 were significantly higher in GC patients. More CCR9+ pDCs were found infiltrating carcinoma tissue in patients with later T staging and lymph node metastasis and conferred a poor prognosis.

CONCLUSION

CCR9-CCL25 interaction might play an important role in mediating PDC homing to metastatic lymph nodes and carcinoma tissue, which contributed to the formation of tumor immunosuppressive microenvironment and poor prognosis.

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.

Phenotypes and Functions of Human Dendritic Cell Subsets in the Tumor Microenvironment

Dendritic cells (DCs) play a key role in the antitumor immunity, as they are at the interface of innate and adaptive immunity. This important task can only be performed thanks to the broad range of mechanisms that DCs can perform to activate other immune cells. As DCs are well known for their outstanding capacity to prime and activate T cells through antigen presentation, DCs were intensively investigated during the past decades. Numerous studies have identified new DC subsets, leading to a large variety of subsets commonly separated into cDC1, cDC2, pDCs, mature DCs, Langerhans cells, monocyte-derived DCs, Axl-DCs, and several other subsets. Here, we review the specific phenotypes, functions, and localization within the tumor microenvironment (TME) of human DC subsets thanks to flow cytometry and immunofluorescence but also with the help of high-output technologies such as single-cell RNA sequencing and imaging mass cytometry (IMC).

Therapeutic targeting of regulatory T cells in cancer

The success of immunotherapy in oncology underscores the vital role of the immune system in cancer development. Regulatory T cells (Tregs) maintain a fine balance between autoimmunity and immune suppression. They have multiple roles in the tumor microenvironment (TME) but act particularly in suppressing T cell activation. This review focuses on the detrimental and sometimes beneficial roles of Tregs in tumors, our current understanding of recruitment and stabilization of Tregs within the TME, and current Treg-targeted therapeutics. Research identifying subpopulations of Tregs and their respective functions and interactions within the complex networks of the TME will be crucial to develop the next generation of immunotherapies. Through these advances, Treg-targeted immunotherapy could have important implications for the future of oncology.

Transcriptome profile and clinical characterization of ICOS expression in gliomas

Inducible co-stimulator (ICOS), an immune costimulatory molecule, has been found to play an essential role across various malignancies. This study investigated the transcriptome profile and clinical characterization of ICOS in gliomas. Clinical information and transcriptome data of 301 glioma samples were downloaded from the Chinese Glioma Genome Atlas (CGGA) dataset for analysis (CGGA301 cohort). Furthermore, the results were validated in 697 samples with RNAseq data from the TCGA glioma dataset and 325 gliomas with RNAseq data from the CGGA325 dataset. Immunohistochemistry was performed to evaluate ICOS protein expression across different WHO grades in a tissue microarray (TMA). In addition, single-cell sequencing data from CGGA and GSE 163108 datasets were used to analyze the ICOS expression across different cell types. Statistical analyses and figure production were performed with R-language. We found that ICOS was significantly upregulated in higher-grade, IDH wild type, and mesenchymal subtype of gliomas. Functional enrichment analyses revealed that ICOS was mainly involved in glioma-related immune response. Moreover, ICOS showed a robust correlation with other immune checkpoints, including the PD1/PD-L1/PD-L2 pathway, CTLA4, ICOSL (ICOS ligand), and IDO1. Subsequent Tumor Immune Dysfunction and Exclusion (TIDE) analysis revealed that GBM patients with higher ICOS expression seemed to be more sensitive to ICB therapy. Furthermore, based on seven clusters of metagenes, GSVA identified that ICOS was tightly associated with HCK, LCK, MHC-I, MHC-II, STAT1, and interferon, especially with LCK, suggesting a strong correlation between ICOS and T-cell activity in gliomas. In cell lineage analysis, Higher-ICOS gliomas tended to recruit dendritic cells, monocytes, and macrophages into the tumor microenvironment. Single-cell sequencing analysis indicated that ICOS was highly expressed by regulatory T cells (Tregs), especially in mature Tregs. Finally, patients with higher ICOS had shortened survival. ICOS was an independent prognosticator for glioma patients. In conclusion, higher ICOS is correlated with more malignancy of gliomas and is significantly associated with Treg activity among glioma-related immune responses. Moreover, ICOS could contribute as an independent prognostic factor for gliomas. Our study highlights the role of ICOS in glioma and may facilitate therapeutic strategies targeting ICOS for glioma.

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.

Different subpopulations of regulatory T cells in human autoimmune disease, transplantation, and tumor immunity

CD4⁺CD25⁺ regulatory T cells (Tregs), a subpopulation of naturally CD4⁺ T cells that characteristically express transcription factor Forkhead box P3 (FOXP3), play a pivotal role in the maintenance of immune homeostasis and the prevention of autoimmunity. With the development of biological technology, the understanding of plasticity and stability of Tregs has been further developed. Recent studies have suggested that human Tregs are functionally and phenotypically diverse. The functions and mechanisms of different phenotypes of Tregs in different disease settings, such as tumor microenvironment, autoimmune diseases, and transplantation, have gradually become hot spots of immunology research that arouse extensive attention. Among the complex functions, CD4⁺CD25⁺FOXP3⁺ Tregs possess a potent immunosuppressive capacity and can produce various cytokines, such as IL‐2, IL‐10, and TGF‐β, to regulate immune homeostasis. They can alleviate the progression of diseases by resisting inflammatory immune responses, whereas promoting the poor prognosis of diseases by helping cells evade immune surveillance or suppressing effector T cells activity. Therefore, methods for targeting Tregs to regulate their functions in the immune microenvironment, such as depleting them to strengthen tumor immunity or expanding them to treat immunological diseases, need to be developed. Here, we discuss that different subpopulations of Tregs are essential for the development of immunotherapeutic strategies involving Tregs in human diseases.

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.

The tumor immune-microenvironment in gastric cancer

AIMS AND BACKGROUND

The tumor microenvironment significantly influences malignant behavior and progression. Many components are involved in the tumor microenvironment, including extracellular matrix, stromal cells, immune and inflammatory cells, as well as cytokines that promote tumor development with complex interactions through the exchange of molecular information. It is now known that tumor immune escape may be influenced by the tumor microenvironment. The aim of this work is to conduct a review of the tumor immune-microenvironment in gastric cancer.

METHODS

We review the current knowledge of several immune cells involved in the gastric tumor microenvironment. In addition, a brief description of immunotherapy strategies for gastric cancer is also reviewed.

CONCLUSIONS

Among immune cell populations, lymphocytes, macrophages, dendritic cells and myeloid-derived suppressor cells are revealed to make the difference in promoting or suppressing gastric tumorigenesis, either directly or indirectly, via regulating the immune responses. Understanding these interactions in detail within the tumor immune-microenvironment will contribute to unraveling new therapeutic targets.

Early antitumor activity of oral Langerhans cells is compromised by a carcinogen

Early diagnosis of oral squamous cell carcinoma (OSCC) remains an unmet clinical need. Therefore, elucidating the initial events of OSCC preceding tumor development could benefit OSCC prognosis. Here, we define the Langerhans cells (LCs) of the tongue and demonstrate that LCs protect the epithelium from carcinogen-induced OSCC by rapidly priming αβT cells capable of eliminating γH2AX⁺ epithelial cells, whereas γδT and natural killer cells are dispensable. The carcinogen, however, dysregulates the epithelial resident mononuclear phagocytes, reducing LC frequencies, while dendritic cells (DCs), macrophages, and plasmacytoid DCs (pDCs) populate the epithelium. Single-cell RNA-sequencing analysis indicates that these newly differentiated cells display an immunosuppressive phenotype accompanied by an expansion of T regulatory (Treg) cells. Accumulation of the Treg cells was regulated, in part, by pDCs and precedes the formation of visible tumors. This suggests LCs play an early protective role during OSCC, yet the capacity of the carcinogen to dysregulate the differentiation of mononuclear phagocytes facilitates oral carcinogenesis.

Hypoxia promotes the tolerogenic phenotype of plasmacytoid dendritic cells in head and neck squamous cell carcinoma

Objective

We aim to review the roles of plasmacytoid dendritic cells (pDCs) in head and neck squamous cell carcinoma (HNSCC) and explore the effects of hypoxia on the tolerogenic transformation of pDCs.

Background

pDCs, best known as professional type I interferon‐secreting cells, play key roles in immune surveillance and antitumor immunity. Recently, pDCs have been shown to be tolerogenic and correlate with poor prognosis in a variety of cancers, including HNSCC. However, it remains unclear what drives the tolerogenic transformation of pDCs in the HNSCC microenvironment. Hypoxia, a prominent hallmark of the tumor microenvironment (TME) of HNSCC, can interfere with multiple immune cells and establish an immunosuppressive TME.

Methods

In this review, we summarize the antitumor and protumor functions of pDCs, explore the effects of hypoxia on the migration and maturation of pDCs, and discuss related mechanisms in HNSCC.

Conclusions

pDCs mainly display protumor functions in HNSCC. The hypoxic TME in HNSCC can enhance the migration of pDCs and inhibit the differentiation and maturation of pDCs, promoting the tolerogenic phenotype of pDCs.

Gastric Microbiota beyond H. pylori: An Emerging Critical Character in Gastric Carcinogenesis

Gastric cancer (GC) is one of the global leading causes of cancer death. The association between Helicobacter pylori, which is a predominant risk factor for GC, with GC development has been well-studied. Recently, accumulating evidence has demonstrated the presence of a large population of microorganisms other than H. pylori in the human stomach. Existing sequencing studies have revealed microbial compositional and functional alterations in patients with GC and highlighted a progressive shift in the gastric microbiota in gastric carcinogenesis with marked enrichments of oral or intestinal commensals. Moreover, using a combination of gastric bacterial signatures, GC patients could be significantly distinguished from patients with gastritis. These findings, therefore, emphasize the importance of a collective microbial community in gastric carcinogenesis. Here, we provide an overview of non-H. pylori gastric microbes in gastric carcinogenesis. The molecular mechanisms of gastric microbes-related carcinogenesis and potential clinical applications of gastric microbiota as biomarkers of GC are also explored.

The Role of Plasmacytoid Dendritic Cells in Cancers

Plasmacytoid dendritic cells (pDCs) are a special subtype of dendritic cells with the morphology of plasma cells. pDCs produce massive amounts of type I interferon (IFN-I), which was originally found to play an extremely pivotal role in antiviral immunity. Interestingly, accumulated evidence indicates that pDCs can also play an important role in tumorigenesis. In the human body, most of the IFN-α is secreted by activated pDCs mediated by toll-like receptor (TLR) stimulation. In many types of cancer, tumors are infiltrated by a large number of pDCs, however, these pDCs exhibit no response to TLR stimulation, and reduced or absent IFN-α production. In addition, tumor-infiltrating pDCs promote recruitment of regulatory T cells (Tregs) into the tumor microenvironment, leading to immunosuppression and promoting tumor growth. In this review, we discuss recent insights into the development of pDCs and their roles in a variety of malignancies, with special emphasis on the basic mechanisms.

The Positive and Negative Immunoregulatory Role of B7 Family: Promising Novel Targets in Gastric Cancer Treatment

Gastric cancer (GC), with a heterogeneous nature, is the third leading cause of death worldwide. Over the past few decades, stable reductions in the incidence of GC have been observed. However, due to the poor response to common treatments and late diagnosis, this cancer is still considered one of the lethal cancers. Emerging methods such as immunotherapy with immune checkpoint inhibitors (ICIs) have transformed the landscape of treatment for GC patients. There are presently eleven known members of the B7 family as immune checkpoint molecules: B7-1 (CD80), B7-2 (CD86), B7-H1 (PD-L1, CD274), B7-DC (PDCD1LG2, PD-L2, CD273), B7-H2 (B7RP1, ICOS-L, CD275), B7-H3 (CD276), B7-H4 (B7x, B7S1, Vtcn1), B7-H5 (VISTA, Gi24, DD1α, Dies1 SISP1), B7-H6 (NCR3LG1), B7-H7 (HHLA2), and Ig-like domain-containing receptor 2 (ILDR2). Interaction of the B7 family of immune-regulatory ligands with the corresponding receptors resulted in the induction and inhibition of T cell responses by sending co-stimulatory and co-inhibitory signals, respectively. Manipulation of the signals provided by the B7 family has significant potential in the management of GC.

Interplay and cooperation of Helicobacter pylori and gut microbiota in gastric carcinogenesis

Chronic Helicobacter pylori infection is a critical risk factor for gastric cancer (GC). However, only 1–3 % of people with H. pylori develop GC. In gastric carcinogenesis, non-H. pylori bacteria in the stomach might interact with H. pylori. Bacterial dysbiosis in the stomach can strengthen gastric neoplasia development via generating tumor-promoting metabolites, DNA damaging, suppressing antitumor immunity, and activating oncogenic signaling pathways. Other bacterial species may generate short-chain fatty acids like butyrate that may inhibit carcinogenesis and inflammation in the human stomach. The present article aimed at providing a comprehensive overview of the effects of gut microbiota and H. pylori on the development of GC. Next, the potential mechanisms of intestinal microbiota were discussed in gastric carcinogenesis. We also disserted the complicated interactions between H. pylori, intestinal microbiota, and host in gastric carcinogenesis, thus helping us to design new strategies for preventing, diagnosing, and treating GC.

Plasmacytoid Dendritic Cells in Patients with MGUS and Multiple Myeloma

Background: Plasmacytoid dendritic cells (pDCs) play prominent roles in mediating innate and adaptive immune responses. However, it is unclear how pDCs contribute to the immunosuppressive tumor microenvironment described in multiple myeloma (MM). Methods: Newly diagnosed myeloma patients (MM, n = 37) were analyzed to determine the pDC counts in comparison to peripheral blood (PB, n = 53) and bone marrow (BM, n = 10) samples of age-matched healthy donors (HD) using flow cytometry. Second, proliferation of myeloma tumor cells in the presence of freshly isolated pDCs was examined. Third, production of IFNα by pDCs co-cultured with MM cells was determined by intracellular staining. Results: We found a highly significant reduction of circulating pDCs (p < 0.0001) and in bone marrow (p < 0.0001) of MM patients compared to HD. We also observed a significant decrease of pDCs (p = 0.004) in BM in patients with monoclonal gammopathy of undetermined significance (MGUS, n = 12). Importantly, we determined that pDCs promote proliferation specifically of MM cells and not the stromal cells and that pDCs secrete IFNα upon co-culture with MM tumor cells. Conclusions: Our results show altered pDC frequencies in the BM microenvironment in MGUS and MM patients at diagnosis. We showed the tumor-promoting function of pDCs that may mediate immune deficiencies affecting long-term disease control and treatment outcome.

Recruitment and Expansion of Tregs Cells in the Tumor Environment-How to Target Them?

Simple Summary

The immune response against cancer is generated by effector T cells, among them cytotoxic CD8⁺ T cells that destroy cancer cells and helper CD4⁺ T cells that mediate and support the immune response. This antitumor function of T cells is tightly regulated by a particular subset of CD4⁺ T cells, named regulatory T cells (Tregs), through different mechanisms. Even if the complete inhibition of Tregs would be extremely harmful due to their tolerogenic role in impeding autoimmune diseases in the periphery, the targeted blockade of their accumulation at tumor sites or their targeted depletion represent a major therapeutic challenge. This review focuses on the mechanisms favoring Treg recruitment, expansion and stabilization in the tumor microenvironment and the therapeutic strategies developed to block these mechanisms.

Abstract

Regulatory T cells (Tregs) are present in a large majority of solid tumors and are mainly associated with a poor prognosis, as their major function is to inhibit the antitumor immune response contributing to immunosuppression. In this review, we will investigate the mechanisms involved in the recruitment, amplification and stability of Tregs in the tumor microenvironment (TME). We will also review the strategies currently developed to inhibit Tregs’ deleterious impact in the TME by either inhibiting their recruitment, blocking their expansion, favoring their plastic transformation into other CD4⁺ T-cell subsets, blocking their suppressive function or depleting them specifically in the TME to avoid severe deleterious effects associated with Treg neutralization/depletion in the periphery and normal tissues.

Role of the Gastric Microbiome in Gastric Cancer: From Carcinogenesis to Treatment

The development of sequencing technology has expanded our knowledge of the human gastric microbiome, which is now known to play a critical role in the maintenance of homeostasis, while alterations in microbial community composition can promote the development of gastric diseases. Recently, carcinogenic effects of gastric microbiome have received increased attention. Gastric cancer (GC) is one of the most common malignancies worldwide with a high mortality rate. Helicobacter pylori is a well-recognized risk factor for GC. More than half of the global population is infected with H. pylori, which can modulate the acidity of the stomach to alter the gastric microbiome profile, leading to H. pylori-associated diseases. Moreover, there is increasing evidence that bacteria other than H. pylori and their metabolites also contribute to gastric carcinogenesis. Therefore, clarifying the contribution of the gastric microbiome to the development and progression of GC can lead to improvements in prevention, diagnosis, and treatment. In this review, we discuss the current state of knowledge regarding changes in the microbial composition of the stomach caused by H. pylori infection, the carcinogenic effects of H. pylori and non-H. pylori bacteria in GC, as well as the potential therapeutic role of gastric microbiome in H. pylori infection and GC.

Functions of Dendritic Cells and Its Association with Intestinal Diseases

Dendritic cells (DCs), including conventional DCs (cDCs) and plasmacytoid DCs (pDCs), serve as the sentinel cells of the immune system and are responsible for presenting antigen information. Moreover, the role of DCs derived from monocytes (moDCs) in the development of inflammation has been emphasized. Several studies have shown that the function of DCs can be influenced by gut microbes including gut bacteria and viruses. Abnormal changes/reactions in intestinal DCs are potentially associated with diseases such as inflammatory bowel disease (IBD) and intestinal tumors, allowing DCs to be a new target for the treatment of these diseases. In this review, we summarized the physiological functions of DCs in the intestinal micro-environment, their regulatory relationship with intestinal microorganisms and their regulatory mechanism in intestinal diseases.

An Iron Metabolism-Related SLC22A17 for the Prognostic Value of Gastric Cancer

Purpose

Gastric cancer (GC) is a type of malignant cancer with a poor prognosis. The iron’s metabolism plays an important role in the process of GC. The aim of this study was to evaluate the effectiveness of SLC22A17, associated with iron metabolism, in predicting the prognosis of GC patients.

Materials and Methods

We analyzed genes related to iron metabolism of gastric cancer mRNA-seq data from TCGA database. We identified an iron metabolism-related SLC22A17 as an independent prognostic factor using univariate and multivariate Cox regression analysis.

Results

Further research showed that SLC22A17 was related with many pathways involved in the process of gastric cancer, and the expression was associated with diverse cancer-infiltrating immune cells. The expression of SLC22A17 was associated with T (Topography).

Conclusion

We validated that SLC22A17 associated with iron metabolism could serve as a prognostic biomarker for GC patients.

Comprehensive Phenotyping of Dendritic Cells in Cancer Patients by Flow Cytometry

Dendritic cells (DCs) play a crucial role in the complex interplay between tumor cells and the immune system. During the elimination phase of cancer immunoediting, immunostimulatory DCs are critical for the control of tumor growth. During the escape phase, regulatory DCs sustain tumor tolerance and contribute to the development of the immunosuppressive tumor microenvironment that characterizes this phase. Moreover, increasing evidence indicates that DCs are also critical for the success of cancer immunotherapy. Hence, there is increasing need to fully characterize DC subsets and their activatory/inhibitory profile in cancer patients. In this review, we describe the role played by different DC subsets in the different phases of cancer immunoediting, the function exerted by different activatory and inhibitory molecules expressed on DC surface, and the cytokines produced by distinct DC subsets, in order to provide an overview on the DC features that may be useful to be assessed when dealing with the flow cytometric characterization of DCs in cancer patients. © 2020 International Society for Advancement of Cytometry.

ICOS agonism by JTX-2011 (vopratelimab) requires initial T cell priming and Fc cross-linking for optimal T cell activation and anti-tumor immunity in preclinical models

Immunotherapy checkpoint inhibitors, such as antibodies targeting PD-1 and CTLA-4, have demonstrated the potential of harnessing the immune system to treat cancer. However, despite encouraging results particularly with respect to survival, only a minority of patients benefit from these therapies. In clinical studies aimed at understanding changes in the immune system following immunotherapy treatment, ICOS (Inducible T cell CO-Stimulator) was shown to be significantly up-regulated on CD4+ T cells and this was associated with clinical activity, indicating that ICOS stimulatory activity may be beneficial in the treatment of solid tumors. In this report, we describe the generation of specific, species cross-reactive, agonist antibodies to ICOS, including the humanized clinical candidate, JTX-2011 (vopratelimab). Preclinical studies suggest that the ICOS stimulating antibodies require Fc receptor cross-linking for optimal agonistic activity. Notably, the ICOS antibodies do not exhibit superagonist properties but rather require T cell receptor (TCR)-mediated upregulation of ICOS for agonist activity. Treatment with the ICOS antibodies results in robust anti-tumor benefit and long-term protection in preclinical syngeneic mouse tumor models. Additional benefit is observed when the ICOS antibodies are administered in combination with anti-PD-1 and anti-CTLA-4 therapies. Based on the preclinical data, JTX-2011 is currently being developed in the clinical setting for the treatment of solid tumors.

Reviving up dendritic cells can run cancer immune wheel in non-small cell lung cancer: a prospective two-arm study

BACKGROUND AND AIM

Lung cancer is the number one cause of cancer-related deaths. Dendritic cells (DCs) are heterogeneous components of innate immunity that play a crucial role in the anti-tumor T cell immunity and may represent a promising approach for tumor immunotherapy. In this study, we aimed to evaluate the frequency of the two major subsets of DCs; plasmacytoid dendritic cells (pDCs) and monocytic dendritic cells (mDCs) in non-small cell lung cancer (NCSLC) and correlating them with different clinicopathologic features and survival outcomes.

PATIENTS AND METHODS

This study was a case-controlled one, included 50 patients with denovo pathologically confirmed NSCLC and 20 healthy controls of comparable age and gender. After diagnosis and staging of patients, the frequency of DCs was evaluated using flow cytometry.

RESULTS

We unveiled significantly reduced levels of pDCs (P = 0.024), and mDCs (P = 0.013) in NSCLC patients compared to controls. Furthermore, there was a significant accumulation of pDCs in non-metastatic patients compared to metastatic ones (P < 0.0001), while there was no significant (P = 0.6) differences in mDCs, and mDCs/pDCs ratio (P = 0.9). There was a Significant negative correlation (r = - 0.3, P = 0.04) between OS and mDCs. On the other hand, there was a significantly higher OS with pDCs ≥ 0.82 compared to patients with pDCs < 0.82, log rank Ch² = 12.128, P < 0.0001.

CONCLUSION

Despite the controversy about the prognostic role of pDCs not only in NSCLC but also in other solid tumors, our study sheds light on the possible prognostic impact of pDCs and mDCs on treatment outcomes of NSCLC patients.

The role of non-H. pylori bacteria in the development of gastric cancer

There is a complex ecosystem of bacteria and other microorganisms inside and outside the human body, which play an intricate role in maintaining health. In recent years, many researches focused on the relationship between microorganisms and cancer. Studies have identified that numerous microbes are presented in human stomach, which are closely linked to the development of gastric cancer (GC). Helicobacter pylori (H. pylori) is the mostly well-studied bacterial pathogen in the stomach, which account for the vast majority of GC. However, recent studies have found that microflora dysbiosis was occurred in mucosa of GC patients, and evidences have potentially proved that microbes other than H. pylori are also contribute to the development of GC, while the overall knowledge is still limited. In this review, we summarized the role of gastric flora in GC, especially the possible role of non-H. pylori bacteria in the development of GC. These knowledges and awareness may open doors for new therapeutic strategies of GC.

Plasmacytoid dendritic cells in the eye

Plasmacytoid dendritic cells (pDCs) are a unique subpopulation of immune cells, distinct from classical dendritic cells. pDCs are generated in the bone marrow and following development, they typically home to secondary lymphoid tissues. While peripheral tissues are generally devoid of pDCs during steady state, few tissues, including the lung, kidney, vagina, and in particular ocular tissues harbor resident pDCs. pDCs were originally appreciated for their potential to produce large quantities of type I interferons in viral immunity. Subsequent studies have now unraveled their pivotal role in mediating immune responses, in particular in the induction of tolerance. In this review, we summarize our current knowledge on pDCs in ocular tissues in both mice and humans, in particular in the cornea, limbus, conjunctiva, choroid, retina, and lacrimal gland. Further, we will review our current understanding on the significance of pDCs in ameliorating inflammatory responses during herpes simplex virus keratitis, sterile inflammation, and corneal transplantation. Moreover, we describe their novel and pivotal neuroprotective role, their key function in preserving corneal angiogenic privilege, as well as their potential application as a cell-based therapy for ocular diseases.

Role of Inducible Co-Stimulator (ICOS) in cancer immunotherapy

Introduction: The promotion of antitumor response by targeting co-stimulatory B7 superfamily members has become evident to create a new wave of cancer immunotherapy. Inducible Co-Stimulator (ICOS), which is expressed on activated T cells, gained interest in the translational medicine community.Areas covered: We performed an extensive literature review using the keywords 'ICOS' and 'cancer', and the Clinicaltrials.gov database for early phase clinical trials targeting ICOS. In this review, we highlight the dual role of ICOS in oncogenesis in different malignancies. We summarize the current state of knowledge about ICOS/ICOSL pathway targeting by immunotherapies.Expert opinion: Due to its multifaceted link with anti-tumor immunity, both antagonist and agonist antibodies might be of interest to target the ICOS/ICOSL pathway for tumor treatment. Indeed, ICOS activation might potentiate the effect of an inhibitory checkpoint blockade, while its neutralization could decrease the function of immunosuppressive Tregs and inhibit lymphoid tumor cells expressing Tfh markers.

Plasmacytoid Dendritic Cells and ICOS+ Regulatory T Cells Predict Poor Prognosis in Gastric Cancer: A Pilot Study

Background: Regulatory T cells (Tregs) and plasmacytoid dendritic cells (pDCs) are the main immunosuppressive cells in tumor microenvironment of gastric cancer (GC). In this prospective study, the association of prognosis with Tregs subsets and pDCs were further analyzed.

Methods: pDCs, Tregs population and its expression of inducible costimulator (ICOS) were analyzed in peripheral blood from 41 GC patients by multicolor flow cytometry. These cell populations in carcinoma tissue, peritumor tissue and normal gastric mucosa from 87 GC patients were also detected by immunohistochemistry and double immunofluorescence.

Results: Both ICOS⁺Foxp3⁺Treg cells (P=0.0341 and P=0.0298, respectively) and pDC (P=0.0237 and P=0.0083, respectively) in peripheral blood and tumor tissue could predict poor clinical outcome in GC patients. However, the total Foxp3⁺Tregs in the GC tissue didn't correlated with the outcome (P=0.4299). No correlation of CD4⁺ T cell or CD8⁺ T cell frequency could be found with clinical outcome neither in peripheral blood nor in tumor tissue.

Conclusions: ICOS⁺Tregs and pDCs could predict poor prognosis of GC, targeting ICOS-L/ICOS costimulation axis may be a potential treatment for GC.

Myeloid and Plasmacytoid Dendritic Cells and Cancer - New Insights

Dendritic cells (DCs) use effective mechanisms to combat antigens and to bring about adaptive immune responses through their ability to stimulate näive T cells. At present, four major cell types are categorised as DCs: Classical or conventional (cDCs), Plasmacytoid (pDCs), Langerhans cells (LCs), and monocyte-derived DCs (Mo-DCs). It was suggested that pDCs, CD1c+ DCs and CD141+ DCs in humans are equivalent to mouse pDCs, CD11b+ DCs and CD8α+ DCs, respectively. Human CD141+ DCs compared to mouse CD8α+ DCs have remarkable functional and transcriptomic similarities. Characteristic markers, transcription factors, toll-like receptors, T helpers (Th) polarisation, cytokines, etc. of DCs are discussed in this review. Major histocompatibility complex (MHC) I and II antigen presentation, cross-presentation and Th polarisation are defined, and the dual role of DCs in the tumour is discussed. Human DCs are the main immune cells that orchestrate the immune response in the tumour microenvironment.

Mass cytometry dissects T cell heterogeneity in the immune tumor microenvironment of common dysproteinemias at diagnosis and after first line therapies

Dysproteinemias progress through a series of clonal evolution events in the tumor cell along with the development of a progressively more “permissive” immune tumor microenvironment (iTME). Novel multiparametric cytometry approaches, such as cytometry by time-of-flight (CyTOF) combined with novel gating algorithms can rapidly characterize previously unknown phenotypes in the iTME of tumors and better capture its heterogeneity. Here, we used a 33-marker CyTOF panel to characterize the iTME of dysproteinemia patients (MGUS, multiple myeloma—MM, smoldering MM, and AL amyloidosis) at diagnosis and after standard of care first line therapies (triplet induction chemotherapy and autologous stem cell transplant—ASCT). We identify novel subsets, some of which are unique to the iTME and absent from matched peripheral blood samples, with potential roles in tumor immunosurveillance as well as tumor immune escape. We find that AL amyloidosis has a distinct iTME compared to other dysproteinemias with higher myeloid and “innate-like” T cell subset infiltration. We show that T cell immune senescence might be implicated in disease pathogenesis in patients with trisomies. Finally, we demonstrate that the early post-ASCT period is associated with an increase of senescent and exhausted subsets, which might have implications for the rational selection of post-ASCT therapies.

The role of dendritic cells in cancer

Cancer immunotherapy harnesses the ability of the immune system to recognize and eliminate cancer. The potent ability of dendritic cells (DCs) to initiate and regulate adaptive immune responses underpins the successful generation of anti-tumor immune responses. DCs are a heterogeneous leukocyte population comprised of distinct subsets that drive specific types of immune responses. Understanding how DCs induce tumor immune responses and the mechanisms adopted by tumors to evade DC surveillance is essential to render immunotherapies more effective. This review discusses current knowledge of the roles played by different DC subsets in human cancer and how these might be manipulated as new immunotherapeutics to improve CD8⁺ T cell-mediated immune responses, with a particular focus on the conventional type 1 DCs (cDC1).

CD4+T Cell Subset Profiling in Biliary Atresia Reveals ICOS- Regulatory T Cells as a Favorable Prognostic Factor

Biliary atresia (BA) is a destructive pediatric liver disease and CD4+T cell activation is demonstrated to play an important role in BA. However, a comprehensive scenario regarding the involvement of CD4+T cell subsets to the development of BA remains unclear. Here, we aim to explore the infiltration of CD4+T cell subsets and their clinical significance in BA. In the present study, thirty BA liver samples were collected during surgery and were divided into good (BA1, n = 16) and poor prognosis (BA2, n = 14), with samples from choledochal cyst patients (n = 8) as control. By using multiplex immunohistochemistry, we evaluated the infiltration level of CD4+T cell subsets in the portal areas. RT-qPCR and flow cytometry were further applied to explore detailed features of Treg subsets. We revealed that hepatic infiltrating Th1, Th2, Th17, and ICOS+Treg cells were significantly increased in BA patients compared to controls and were negatively associated with prognosis, while high infiltrating ICOS-Tregs showed a favorable outcome. Phenotypic analysis indicated that, in contrast to ICOS+Tregs, ICOS-Tregs were mainly CD45RAhiCD45ROlow, and preferentially expressed more CD73. Besides, RT-qPCR revealed elevated expression of CD25, CD73, TGF-β, and BCL-2 genes in ICOS-Tregs. Finally, functional assay confirmed that ICOS-Tregs had a higher suppressive capacity to cytokine secretion and were more resistant to apoptosis in vitro. Collectively, we demonstrate that a mixed immune response is involved in BA pathogenesis, and the globally enhanced effector CD4+T cell response is associated with unfavorable prognosis, highly suppressive ICOS-Tregs is a protective factor and may serve an important reference to predict prognosis.

Recent advances in the study of regulatory T cells in gastric cancer

Gastric cancer (GC), which features a complex pathogenesis and mechanism, remains refractory. FOXP3⁺ regulatory T cells (Tregs), which have been implicated in the progression of gastric cancer, play an immunosuppressive role in the tumor microenvironment. However, the prognostic value of Treg infiltration is still controversial in GC patients. Recently, the association of Tregs with the clinicopathological characteristics of GC patients, the prognostic value of Tregs alone or its combination with other factors to GC patients, the role of Tregs in GC tumor microenvironment, clinical applications and Tregs-targeted therapies for GC patients have become hot issues. In this review, we are going to discuss these scientific researches which focused on these topics.

Dendritic Cells and Cancer: From Biology to Therapeutic Intervention

Inducing effective anti-tumor immunity has become a major therapeutic strategy against cancer. Dendritic cells (DC) are a heterogenous population of antigen presenting cells that infiltrate tumors. While DC play a critical role in the priming and maintenance of local immunity, their functions are often diminished, or suppressed, by factors encountered in the tumor microenvironment. Furthermore, DC populations with immunosuppressive activities are also recruited to tumors, limiting T cell infiltration and promoting tumor growth. Anti-cancer therapies can impact the function of tumor-associated DC and/or alter their phenotype. Therefore, the design of effective anti-cancer therapies for clinical translation should consider how best to boost tumor-associated DC function to drive anti-tumor immunity. In this review, we discuss the different subsets of tumor-infiltrating DC and their role in anti-tumor immunity. Moreover, we describe strategies to enhance DC function within tumors and harness these cells for effective tumor immunotherapy.

Cell-free miR-17-5p as a diagnostic biomarker for gastric cancer inhibits dendritic cell maturation

Purpose

Gastric cancer (GC) patients display aberrant miRNA expression and defective dendritic cell function. However, the role of cancer cell-derived oncomiR in GC detection and dendritic cell (DC) maturation remains largely elusive.

Methods

Candidate miRNAs were selected by deep sequencing (8 GC plasma samples vs 8 control plasma samples; 8 GC tissues vs 8 adjacent normal gastric tissues) and confirmed by PCR with 164 plasma samples and 72 formalin-fixed paraffin-embedded GC tissue samples. Their diagnostic performance was evaluated by receiver operating characteristic curve. Cy3 fluorescence signals in DCs, exposed to conditioned medium obtained from BGC-823 cells pre-transfected with Cy3-miR-17-5p, were determined by flow cytometry and visualized by confocal microscopy. Functional and phenotypical alterations of DCs were assayed when DCs were transfected with miR-17-5p in vitro.

Results

Deep sequencing and RT-PCR confirmed that five shared miRNAs were upregulated in plasma and tissue samples of GC patients. Cell-free miR-17-5p was superior to others in GC detection with an area under the curve of 0.82, and correlated with lymphatic metastasis and poor overall survival. GC cell-shuttled miR-17-5p can be delivered to immature DCs, and they significantly inhibited LPS-stimulated phenotypic maturation by diminishing the expression of maturation markers (MHC II, CD80 and CD86 molecules). In line with those alterations in the phenotypic markers, functional experiments demonstrated that miR-17-5p triggered an inhibitory effect on DCs endocytic activity and decreased tumor necrosis factor-α and IL-12 secretion, while enhancing IL-10 production. Mixed lymphocyte reaction showed that miR-17-5p inhibited the T cell stimulating effect of DCs and favored regulatory T cells expansion.

Conclusion

GC cell-derived miR-17-5p is a potential biomarker for GC detection. Taken up by DCs, miR-17-5p weakened antitumor immune responses via inhibiting the maturation of dendritic cells.

Immunology of Plasmacytoid Dendritic Cells in Solid Tumors: A Brief Review

The immune response, both innate and adaptive, is a key player in cancer development and progression. Plasmacytoid dendritic cells (pDCs) are a subset of dendritic cells that play one of the central roles in the immune system. They are known mostly as the major IFN type I-producing cells upon stimulation of Toll-like receptors 7 and 9. However, based on current knowledge, the functionality of pDCs is very complex, as they have the ability to affect many other cell types. In the context of the tumor tissue, pDCs were mostly described to show substantial functional defects and therefore contribute to the establishement of immunosuppressive tumor microenvironment. Immunotherapeutic approaches have proven to be one of the most promising treatment strategies in the last decade. In view of this fact, it is crucial to map the complexity of the tumor microenvironment in detail, including less numerous cell types. This review focuses on pDCs in relation to solid tumors. We provide a summary of current data on the role of pDCs in different tumor types and suggest their possible clinical applications.

Positive Immuno-Modulation Following Radiofrequency Assisted Liver Resection in Hepatocellular Carcinoma

Introduction: Hepatocellular carcinoma (HCC) often develops on a background of chronic inflammation and a complex immunosuppressive network with increased regulatory T cells, impaired CD8⁺ T cells and the secretion of immunosuppressive cytokines. Previous clinical studies have reported a superior disease-free survival (DFS) following a radiofrequency-based ablation or resection in HCC tumours compared to conventional liver resection techniques. The aim of this study was to investigate whether there is any correlation with the use of a radiofrequency-assisted liver resection and clinical outcome. Material and Methods: Patients’ peripheral blood was collected prior and 7 days following surgery from patients undergoing a liver resection for HCC. There were 5 liver resections performed using CUSA and 6 liver resections with the RF-based device, Habib^TM 4X. The primary endpoint of the study was to assess the immunological parameters of circulating immune cell populations as well as serum cytokines. The Student’s t-test, chi-square or Fisher’s Exact test were applied for statistical comparisons, as appropriate. Results: Patients undergoing an RF-assisted liver resection with Habib^TM 4X had a significant decrease in the inhibitory Treg cells (p = 0.002) and a significant increase in CD8⁺ T lymphocytes (p = 0.050) and CD4⁺CD45RO⁺/CD4⁺ memory T cells (p = 0.002) compared to those patients undergoing a liver resection with CUSA. It was also noted that the RF-assisted liver resection group had a significant decrease in circulating TGF-ß (p = 0.000), IL10 (p = 0.000) and a significant increase in IFN-gamma (p = 0. 027) and IL-17 compared to the CUSA group. Conclusion: A liver resection with RF-based device Habib^TM 4X was associated with positive immunomodulatory changes in circulating immune cells and circulating cytokines which could explain the significant improvement in DFS.

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

Substantial evidence indicates that gastric microbiota dysbiosis, immune system dysfunction especially immune escape are critical for gastric cancer (GC) occurrence and progression. As two important elements of tumor microenvironment (TME), the relationship between gastric microbiota and tumor-immune microenvironment is still unclear. Our present study aimed to explore the correlation between gastric mucosal microbiota in different microhabitats and its corresponding gastric immunosuppressive cells such as regulatory T cells (Tregs) and plasmacytoid dendritic cells (pDCs) in the TME. A cohort of 64 GC patients without preoperative chemotherapy was enrolled retrospectively, and 60 normal, 61 peritumoral and 59 tumoral tissues were obtained for gastric mucosal microbiota analysis and immunohistochemistry analysis. From different microhabitats, BDCA2⁺pDCs and Foxp3⁺Tregs were observed positively correlated, and increased in tumoral and peritumoral tissues compared to normal ones. The diversity, composition and function of gastric mucosal microbiota also changed more significantly in tumoral tissues than those in normal and peritumoral ones. With pearson's correlation analysis, we found that several non-abundant genera such as Stenotrophomonas and Selenomonas were positively correlated with BDCA2⁺pDCs and Foxp3⁺Tregs, respectively, while Comamonas and Gaiella were negatively correlated with BDCA2⁺pDCs and Foxp3⁺ Tregs, respectively. The increased BDCA2⁺pDCs and Foxp3⁺Tregs might be modulated by gastric mucosal microbiota, both participated in the immunosuppression microenvironment of GC, which might provide evidence to establish new strategies in antitumor therapy targeting on gastric microbiota.