Role of regulatory B cells in gastric cancer: Latest evidence and therapeutics strategies

Investigating the impact of regulatory B cells and regulatory B cell-related genes on bladder cancer progression and immunotherapeutic sensitivity

BACKGROUND

Regulatory B cells (Bregs), a specialized subset of B cells that modulate immune responses and maintain immune tolerance in malignant tumors, have not been extensively investigated in the context of bladder cancer (BLCA). This study aims to elucidate the roles of Bregs and Breg-related genes in BLCA.

METHODS

We assessed Breg infiltration levels in 34 pairs of BLCA and corresponding paracancerous tissues using immunohistochemical staining. We conducted transwell and wound healing assays to evaluate the impact of Bregs on the malignant phenotype of SW780 and T24 cells. Breg-related genes were identified through gene sets and transcriptional analysis. The TCGA-BLCA cohort served as the training set, while the IMvigor210 and 5 GEO cohorts were used as external validation sets. We employed LASSO regression and random forest for feature selection and developed a risk signature using Cox regression. Primary validation of the risk signature was performed through immunohistochemical staining and RT-qPCR experiments using the 34 local BLCA samples. Additionally, we employed transfection assays and flow cytometry to investigate Breg expansion ability and immunosuppressive functions.

RESULTS

Breg levels in BLCA tissues were significantly elevated compared to paracancerous tissues (P < 0.05) and positively correlated with tumor malignancy (P < 0.05). Co-incubation of SW780 and T24 cells with Bregs resulted in enhanced invasion and migration abilities (all P < 0.05). We identified 27 Breg-related genes, including CD96, OAS1, and CSH1, which were integrated into the risk signature. This signature demonstrated robust prognostic classification across the 6 cohorts (pooled HR = 2.25, 95% CI = 1.52-3.33). Moreover, the signature exhibited positive associations with advanced tumor stage (P < 0.001) and Breg infiltration ratios (P < 0.05) in the local samples. Furthermore, the signature successfully predicted immunotherapeutic sensitivity in three cohorts (all P < 0.05). Knockdown of CSH1 in B cells increased Breg phenotype and enhanced suppressive ability against CD8 + T cells (all P < 0.05).

CONCLUSIONS

Bregs play a pro-tumor role in the development of BLCA. The Breg-related gene signature established in this study holds great potential as a valuable tool for evaluating prognosis and predicting immunotherapeutic response in BLCA patients.

Association of lymphocyte subsets with the efficacy and prognosis of PD‑1 inhibitor therapy in advanced gastric cancer: results from a monocentric retrospective study

PURPOSE

This retrospective study aimed to investigate the changes in peripheral blood lymphocyte subsets before and after immunotherapy in patients with advanced gastric cancer and their relationship n with the therapeutic efficacy and clinical prognosis.

METHODS

Peripheral blood lymphocyte subsets, including CD4 + T cells, CD8 + T cells, CD4+/CD8 + ratio, NK cells, Treg cells, and B cells, were collected from 195 patients with advanced gastric cancer who were admitted to the First Hospital of Shanxi Medical University with immunotherapy from January 2020 to October 2021, at the time of diagnosis of advanced gastric cancer, before immunotherapy and after 3 cycles of immunotherapy. T-tests were used to examine the factors influencing the patients' peripheral blood lymphocyte subsets and the changes after immunotherapy. To examine the relationship between lymphocyte subsets and treatment outcomes, ROC curves were plotted using a logistic regression. Kaplan-Meier curve was drawn, and the Log Rank test was carried out to compare the differences in PFS between the different groups. Cox proportional hazards regression model was used to analyze the factors affecting PFS after calibration of other variables.

RESULTS

The proportion of peripheral blood lymphocyte subsets in patients with advanced gastric cancer was affected by age and PD-L1 level. Compared to the baseline, the treatment effective group had higher proportions of CD4 + T cells, a higher CD4+/CD8 + ratio, NK cells and Treg cells, and lower proportions of CD8 + T cells and B cells in the peripheral blood after three cycles of immunotherapy. In the treatment-naive group, there were no significant differences in the lymphocyte subsets. With cut-off values of 30.60% and 18.00%, baseline CD4 + T cell and NK cell ratios were independent predictors of immunotherapy efficacy and PFS. Treg cell ratio, gender, PD-L1 levels, and MMR status all predicted PFS independently.

CONCLUSION

The proportion of peripheral blood lymphocyte subsets was modified in patients who responded to PD-1 inhibitors. Different lymphocyte subpopulation levels can be used as biomarkers to predict immunotherapy efficacy and clinical prognosis in patients with advanced gastric cancer.

Resistance to immune checkpoint inhibitors in gastric cancer

Gastric cancer (GC) is one of the most common gastrointestinal malignancies worldwide. In the past decade, with the development of early diagnostic techniques, a clear decline in GC incidence has been observed, but its mortality remains high. The emergence of new immunotherapies such as immune checkpoint inhibitors (ICIs) has changed the treatment of GC patients to some extent. However, only a small number of patients with advanced GC have a durable response to ICI treatment, and the efficacy of ICIs is very limited. Existing studies have shown that the failure of immunotherapy is mainly related to the development of ICI resistance in patients, but the understanding of the resistance mechanism is still insufficient. Therefore, clarifying the mechanism of GC immune resistance is critical to improve its treatment and clinical benefit. In this review, we focus on summarizing the mechanisms of primary or acquired resistance to ICI immunotherapy in GC from both internal and external aspects of the tumor. At the same time, we also briefly discuss some other possible resistance mechanisms in light of current studies.

Effect of IL-10-producing B cells in peripheral blood and tumor tissue on gastric cancer

BACKGROUND

Interleukin (IL)-10-producing B (B10) cells are generated in response to signals from the tumor microenvironment and promote tumor growth by interacting with B10 cells. We investigated the distributions of immune cells in peripheral blood and tumor tissue samples from patients with gastric cancer (GC).

METHODS

Patients with GC who underwent radical gastrectomy in Seoul St. Mary's Hospital between August 2020 and May 2021 were enrolled in this study. Forty-two samples of peripheral blood were collected, and a pair of gastric mucosal samples (normal and cancerous mucosa; did not influence tumor diagnosis or staging) was collected from each patient after surgery. B10 cells in peripheral blood and cancer mucosa samples were investigated by flow cytometry and immunofluorescence. AGS cells, gastric cancer cell line, were cultured with IL-10 and measured cell death and cytokine secretion. Also, AGS cells were co-cultured with CD19 + B cells and measured cytokine secretion.

RESULTS

The population of B10 cells was significantly larger in the blood of patients with GC compared with controls. In confocal images of gastric mucosal tissues, cancerous mucosa contained more B10 cells than normal mucosa. The population of B10 cells in cancerous mucosa increased with cancer stage. When AGS cells were cultured under cell-death conditions, cellular necrosis was significantly decreased, and proliferation was increased, for 1 day after IL-10 stimulation. Tumor necrosis factor (TNF)-α, IL-8, IL-1β, and vascular endothelial growth factor secretion by cancer cells was significantly increased by coculture of AGS cells with GC-derived CD19+ B cells.

CONCLUSIONS

B cells may be one of the populations that promote carcinogenesis by inducing the production of inflammatory mediators, such as IL-10, in GC. Targeting B10 cells activity could improve the outcomes of antitumor immunotherapy. Video Abstract.

Characteristic of molecular subtype based on lysosome-associated genes reveals clinical prognosis and immune infiltration of gastric cancer

Background

Lysosome are involved in nutrient sensing, cell signaling, cell death, immune responses and cell metabolism, which play an important role in the initiation and development of multiple tumors. However, the biological function of lysosome in gastric cancer (GC) has not been revealed. Here, we aim to screen lysosome-associated genes and established a corresponding prognostic risk signature for GC, then explore the role and underlying mechanisms.

Methods

The lysosome-associated genes (LYAGs) were obtained from MSigDB database. Differentially expressed lysosome-associated genes (DE-LYAGs) of GC were acquired based on the TCGA database and GEO database. According to expression profiles of DE-LYAGs, we divided the GC patients into different subgroups and then explored tumor microenvironment (TME) landscape and immunotherapy response in LYAG subtypes using GSVA, ESTIMATE and ssGSEA algorithms. Univariate Cox regression analysis, LASSO algorithm and multivariate Cox regression analysis were adopted to identify the prognostic LYAGs and then establish a risk model for patients with GC. The Kaplan-Meier analysis, Cox regression analysis and ROC analysis were utilized to evaluate the performance of the prognostic risk model. Clinical GC specimens were also used to verify the bioinformatics results by qRT-PCR assay.

Results

Thirteen DE-LYAGs were obtained and utilized to distinguish three subtypes in GC samples. Expression profiles of the 13 DE-LYAGs predicted prognosis, tumor-related immunological abnormalities and pathway dysregulation in these three subtypes. Furthermore, we constructed a prognostic risk model for GC based on DEG in the three subtypes. The Kaplan-Meier analysis suggested that higher risk score related to short OS rate. The Cox regression analysis and ROC analysis indicated that risk model had independent and excellent ability in predicting prognosis of GC patients. Mechanistically, a remarkable difference was observed in immune cell infiltration, immunotherapy response, somatic mutation landscape and drug sensitivity. qRT-PCR results showed that compared with corresponding adjacent normal tissues, most screened genes showed significant abnormal expressions and the expression change trends were consistent with the bioinformatics results.

Conclusions

We established a novel signature based on LYAGs which could be served as a prognostic biomarker for GC. Our study might provide new insights into individualized prognostication and precision treatment for GC.

Unraveling the role of Breg cells in digestive tract cancer and infectious immunity

Over the past two decades, regulatory B cells (Breg cells or Bregs) have emerged as an immunosuppressive subset of B lymphocytes playing a key role in inflammation, infection, allergy, transplantation, and cancer. However, the involvement of Bregs in various pathological conditions of the gastrointestinal tract is not fully understood and is the subject of much recent research. In this review, we aimed to summarize the current state of knowledge about the origin, phenotype, and suppressive mechanisms of Bregs. The relationship between the host gut microbiota and the function of Bregs in the context of the disturbance of mucosal immune homeostasis is also discussed. Moreover, we focused our attention on the role of Bregs in certain diseases and pathological conditions related to the digestive tract, especially Helicobacter pylori infection, parasitic diseases (leishmaniasis and schistosomiasis), and gastrointestinal neoplasms. Increasing evidence points to a relationship between the presence and number of Bregs and the severity and progression of these pathologies. As the number of cases is increasing year by year, also among young people, it is extremely important to understand the role of these cells in the digestive tract.

Therapeutic strategies for gastric cancer targeting immune cells: Future directions

Gastric cancer (GC) is a malignancy with a high incidence and mortality, and the emergence of immunotherapy has brought survival benefits to GC patients. Compared with traditional therapy, immunotherapy has the advantages of durable response, long-term survival benefits, and lower toxicity. Therefore, targeted immune cells are the most promising therapeutic strategy in the field of oncology. In this review, we introduce the role and significance of each immune cell in the tumor microenvironment of GC and summarize the current landscape of immunotherapy in GC, which includes immune checkpoint inhibitors, adoptive cell therapy (ACT), dendritic cell (DC) vaccines, reduction of M2 tumor-associated macrophages (M2 TAMs), N2 tumor-associated neutrophils (N2 TANs), myeloid-derived suppressor cells (MDSCs), effector regulatory T cells (eT_regs), and regulatory B cells (B_regs) in the tumor microenvironment and reprogram TAMs and TANs into tumor killer cells. The most widely used immunotherapy strategies are the immune checkpoint inhibitor programmed cell death 1/programmed death-ligand 1 (PD-1/PD-L1) antibody, cytotoxic T lymphocyte–associated protein 4 (CTLA-4) antibody, and chimeric antigen receptor T (CAR-T) in ACT, and these therapeutic strategies have significant anti-tumor efficacy in solid tumors and hematological tumors. Targeting other immune cells provides a new direction for the immunotherapy of GC despite the relatively weak clinical data, which have been confirmed to restore or enhance anti-tumor immune function in preclinical studies and some treatment strategies have entered the clinical trial stage, and it is expected that more and more effective immune cell–based therapeutic methods will be developed and applied.

Interleukin-8 Regulates the Autophagy and Apoptosis in Gastric Cancer Cells via Regulating PI3K/Akt Signaling Pathway

Objective. To explore the role and mechanism of interleukin-8-mediated autophagy regulation of gastric cancer (GC) cells in GC. Methods. After cell culture, the SGC7901 cell line was separated into the control group and IL-8 (20 ng/mL) group, IL-8 (40 ng/mL) group, and IL-8 (60 ng/mL) group, to verify the effects of the PI3K/Akt signal path on the modulation of autophagy in GC cells. Western blot detected autophagy markers, ATG12-ATG5 complexes, autophagy-associated pathways, and apoptosis-associated factors in GC cells. Transwell was utilized to identify invasion capability. Results. Compared with the control group, the expression of LC3II, Atg5, ATG7, Beclin1, Bax, C-cas3, C-cas9, P-PI3K, P-Akt, and ATG12-ATG5 was remarkably elevated in the IL-8 (60 ng/mL) group, IL-8 (20 ng/mL) group, and the IL-8 (40 ng/mL) group. The expression of P62 and Bcl-2 in the IL-8 (60 ng/mL) group was also lower than that of the IL-8 (20 ng/mL) group and IL-8 (40 ng/mL) group, in contrast to the controls. The invasive quantity of GC SGC7901 cells in the IL-8 (60 ng/mL) group was also remarkably higher in contrast to the IL-8 (20 ng/mL) and IL-8 (40 ng/mL) groups. The relative expressions of LC3II, Atg5, ATG7, Beclin1, Bax, C-cas3, C-cas9, P-PI3K, P-Akt, and ATG12-ATG5 complex proteins in LY294002 group were considerably elevated. LC3II, Atg5, ATG7, Beclin1, Bax, C-cas3, C-cas9, P-PI3K, P-Akt, and ATG12-ATG5 were decreased in the IL-8 + LY294002 group. The relative expressions of P62 and Bcl-2 proteins in the IL-8 + LY294002 group were remarkably elevated, and the invasion of SGC7901 cells in the IL-8 group was elevated. In contrast to the IL-8 group, the invasion quantity of gastric cancer SGC7901 cells in the IL-8 + LY294002 group was considerably decreased. Conclusion. IL-8 promotes autophagy and aggression and suppresses apoptosis of GC SGC7901 cells by regulating PI3K/AKT pathway phosphorylation.