Regulatory T cells with multiple suppressive and potentially pro-tumor activities accumulate in human colorectal cancer

Causal effects between circulating immune cells and heart failure: evidence from a bidirectional Mendelian randomization study

BACKGROUND

Heart failure (HF) is a prevalent cardiac condition characterized by high mortality and morbidity rates. Immune cells play a pivotal role as crucial biomarkers in assessing the overall immune status of individuals. However, the causal relationship between circulating immune cells and the pathogenesis of HF remains an area requiring further investigation.

OBJECTIVES

The aim of this study was to investigate the genetic interactions between circulating immune cells and HF, and to further elucidate the genetic associations between different lymphocyte subsets and HF.

METHODS

We obtained genetic variants associated with circulating immune cells as instrumental variables (IVs) from the Blood Cell Consortium and publicly available HF summary data. We conducted additional subsets analyses on lymphocyte counts. Our study utilized two-sample and multivariate Mendelian randomization (MVMR) analysis to investigate the causal effect of immune cells on HF. The primary analysis employed inverse variance weighting (IVW) and was complemented by a series of sensitivity analyses.

RESULTS

The findings of the study showed that the IVW model demonstrated a significant correlation between an elevation in lymphocyte count and a decreased risk of HF (OR = 0.97, 95% CI, 0.94 - 1.00, P = 0.032). However, no such correlation was evident in the MVMR analysis for lymphocytes and HF. Furthermore, the examination of the lymphocyte subsets indicated that an increase in CD39+ CD4+ T-cell counts was notably linked to a reduced risk of HF (OR = 0.96, 95% CI, 0.95 - 0.98, P = 0.0002). The MVMR results confirmed that the association between CD39+ CD4+ T-cell counts and HF remained significant. There was no substantial evidence of reverse causality observed between circulating immune cells and HF.

CONCLUSION

Our MR research provided evidence for a causal relationship between lymphocyte cell and HF. Subsets analyses revealed a causal relationship between CD39+ CD4+ T lymphocytes and HF. These findings will facilitate a future understanding of the mechanisms underlying HF.

Exhausted Tumor-infiltrating CD39+CD103+ CD8+ T Cells Unveil Potential for Increased Survival in Human Pancreatic Cancer

In pancreatic ductal adenocarcinoma, the infiltration of CD8+ T cells within the tumor microenvironment correlates with a favorable prognosis. However, a significant proportion of tumor-infiltrating T cells become trapped within the desmoplastic stroma and lack tumor reactivity. Here, we explored different T-cell subsets in pancreatic tumors and adjacent tissues. We identified a subset of CD8+ T cells, double positive (DP) for CD39 and CD103 in pancreatic tumors, which has recently been described to display tumor reactivity in other types of solid tumors. Interestingly, DP CD8+ T cells preferentially accumulated in central tumor tissues compared with paired peripheral tumor and adjacent non-tumor tissues. Consistent with an antigen encounter, DP CD8+ T cells demonstrated higher proliferative rates and displayed an exhausted phenotype, characterized by elevated expression of PD-1 and TIM-3, compared with CD39-CD103- CD8+ T cells. In addition, DP CD8+ T cells exhibited higher expression levels of the tissue trafficking receptors CCR5 and CXCR6, while displaying lower levels of CXCR3 and CXCR4. Importantly, a high proportion of DP CD8+ T cells is associated with increased patient survival. These findings suggest that DP CD8+ T cells with a phenotype reminiscent of that of tumor-reactive T cells are present in pancreatic tumors. The abundance of DP CD8+ T cells could potentially aid in selecting patients for pancreatic cancer immunotherapy trials.

SIGNIFICANCE

Patients with pancreatic cancer with a high proportion of CD39+CD103+ CD8+ T cells exhibiting a tumor-reactive phenotype have improved survival rates, suggesting their potential utility in selecting candidates for immunotherapy trials.

Immune cell infiltrates in peritoneal metastases from colorectal cancer

Background

The presence of peritoneal metastases (PMs) in patients with colorectal cancer (CRC) confers a poor prognosis and only a minority of patients will benefit from the available treatment options. In primary CRC tumors, it is well established that a high infiltration of CD8+ effector T cells correlates to a favorable patient outcome. In contrast, the immune response induced in PMs from CRC and how it relates to patient survival is still unknown. In this study, we characterized the immune infiltrates and the distribution of immune checkpoint receptors on T cells from PMs from CRC, in order to evaluate the potential benefit of checkpoint blockade immunotherapy for this patient group.

Methods

Surgically resected PM tissue from CRC patients (n=22) and synchronous primary tumors (n=8) were processed fresh to single cell suspensions using enzymatic digestion. Surface markers and cytokine production were analyzed using flow cytometry.

Results

T cells dominated the leukocyte infiltrate in the PM specimens analyzed, followed by monocytes and B cells. Comparing two different PMs from the same patient usually showed a similar distribution of immune cells in both samples. The T cell infiltrate was characterized by an activated phenotype and markers of exhaustion were enriched compared with matched circulating T cells, in particular the checkpoint receptors PD-1 and TIGIT. In functional assays most cytotoxic and helper T cells produced INF-γ and TNF following polyclonal stimulation, while few produced IL-17, indicating a dominance of Th1-type responses in the microenvironment of PMs.

Conclusion

Immune cells were present in all PMs from CRC examined. Although infiltrating T cells express markers of exhaustion, they produce Th1-type cytokines when stimulated. These results indicate the possibility to augment tumor-specific immune responses within PMs using checkpoint blockade inhibitors.

CD39 (ENTPD1) in tumors: a potential therapeutic target and prognostic biomarker

As a regulator of the dynamic balance between immune-activated extracellular ATP and immunosuppressive adenosine, CD39 ectonucleotidase impairs the ability of immune cells to exert anticancer immunity and plays an important role in the immune escape of tumor cells within the tumor microenvironment. In addition, CD39 has been studied in cancer patients to evaluate the prognosis, the efficacy of immunotherapy (e.g., PD-1 blockade) and the prediction of recurrence. This article reviews the importance of CD39 in tumor immunology, summarizes the preclinical evidence on targeting CD39 to treat tumors and focuses on the potential of CD39 as a biomarker to evaluate the prognosis and the response to immune checkpoint inhibitors in tumors.

Distribution characteristics and clinical significance of infiltrating T cells in the tumor microenvironment of pancreatic cancer

Tumor-infiltrating lymphocytes (TILs) are important components of the tumor microenvironment (TME). However, the distribution characteristics of TILs and their significance in pancreatic cancer (PC) remain largely unexplored. The levels of TILs, including the total number of T cells, cluster of differentiation (CD)4⁺ T cells, CD8⁺ cytotoxic T lymphocytes (CTLs), regulatory T-cells (Tregs), programmed cell death protein 1⁺ T cells and programmed cell death ligand 1 (PD-L1)⁺ T cells, in the TME of patients with PC were detected using multiple fluorescence immunohistochemistry. The associations between the number of TILs and the clinicopathological characteristics were investigated using χ² tests. In addition, Kaplan-Meier survival and Cox regression analyses were used to assess the prognostic value of these TIL types. Compared with paracancerous tissues, in PC tissues, the proportions of total T cells, CD4⁺ T cells and CD8⁺ CTLs were markedly decreased, while those of Tregs and PD-L1⁺ T cells were significantly increased. The levels of CD4⁺ T cell and CD8⁺ CTL infiltrates were inversely associated with tumor differentiation. Higher infiltrates of Tregs and PD-L1⁺ T cells were closely associated with advanced N and TNM stages. It is important to note that the infiltrates of total T cells, CD4⁺ T cells, Tregs and PD-L1⁺ T cells in the TME were independent risk factors for the prognosis of PC. PC was characterized by an immunosuppressive TME with a decrease in the number of CD4⁺ T cells and CD8⁺ CTLs, and an increase in the number of Tregs and PD-L1⁺ T cells. Overall, the number of total T cells, CD4⁺ T cells, Tregs and PD-L1⁺ T cells in the TME was a potential predictive marker for the prognosis of PC.

New insights into follicular regulatory T cells in the intestinal and tumor microenvironments

Follicular regulatory T (Tfr) cells are a novel and unique subset of effector regulatory T (Treg) cells that are located in germinal centers (GCs). Tfr cells express transcription profiles that are characteristic of both follicular helper T (Tfh) cells and Treg cells and negatively regulate GC reactions, including Tfh cell activation and cytokine production, class switch recombination and B cell activation. Evidence also shows that Tfr cells have specific characteristics in different local immune microenvironments. This review focuses on the regulation of Tfr cell differentiation and function in unique local immune microenvironments, including the intestine and tumor.

Autologous T cell responses to primary human colorectal cancer spheroids are enhanced by ectonucleotidase inhibition

OBJECTIVE

T cells are major effectors of the antitumoural immune response. Their activation by tumour-associated antigens can unleash their proliferation and cytotoxic functions, leading to tumour cell elimination. However, tumour-related immunosuppressive mechanisms including the overexpression of immune checkpoints like programmed cell death protein-1 (PD-1), are also engaged, promoting immune escape. Current immunotherapies targeting these pathways have demonstrated weak efficacy in colorectal cancer (CRC). It is thus crucial to find new targets for immunotherapy in this cancer type.

DESIGN

In a prospective cohort of patients with CRC, we investigated the phenotype of tumour-related and non-tumour related intestinal T cells (n=44), particularly the adenosinergic pathway, correlating with clinical phenotype. An autologous coculture model was developed between patient-derived primary tumour spheroids and their autologous tumour-associated lymphocytes. We used this relevant model to assess the effects of CD39 blockade on the antitumour T cell response.

RESULTS

We show the increased expression of CD39, and its co-expression with PD-1, on tumour infiltrating T cells compared with mucosal lymphocytes. CD39 expression was higher in the right colon and early-stage tumours, thus defining a subset of patients potentially responsive to CD39 blockade. Finally, we demonstrate in autologous conditions that CD39 blockade triggers T cell infiltration and tumour spheroid destruction in cocultures.

CONCLUSION

In CRC, CD39 is strongly expressed on tumour infiltrating lymphocytes and its inhibition represents a promising therapeutic strategy for treating patients.

B cells in the tumor microenvironment: Multi-faceted organizers, regulators, and effectors of anti-tumor immunity

Our understanding of tumor-infiltrating lymphocytes (TILs) is rapidly expanding beyond T cell-centric perspectives to include B cells and plasma cells, collectively referred to as TIL-Bs. In many cancers, TIL-Bs carry strong prognostic significance and are emerging as key predictors of response to immune checkpoint inhibitors. TIL-Bs can perform multiple functions, including antigen presentation and antibody production, which allow them to focus immune responses on cognate antigen to support both T cell responses and innate mechanisms involving complement, macrophages, and natural killer cells. In the stroma of the most immunologically "hot" tumors, TIL-Bs are prominent components of tertiary lymphoid structures, which resemble lymph nodes structurally and functionally. Additionally, TIL-Bs participate in a variety of other lympho-myeloid aggregates and engage in dynamic interactions with the tumor stroma. Here, we summarize our current understanding of TIL-Bs in human cancer, highlighting the compelling therapeutic opportunities offered by their unique tumor recognition and effector mechanisms.

Allogeneic cord blood regulatory T cells can resolve lung inflammation

BACKGROUND AIMS

CD4⁺CD25⁺CD127^lo regulatory T cells (Tregs) are responsible for maintaining immune homeostasis. Tregs can be rendered defective and deficient as a result of the immune imbalance seen in lung injury, and such dysfunction can play a major role in continued tissue inflammation. The authors hypothesized that adoptive therapy with healthy allogeneic umbilical cord blood (UCB)-derived Tregs may be able to resolve inflammation.

RESULTS

Ex vivo-expanded UCB Tregs exhibited a unique phenotype with co-expression of CD45RA⁺CD45RO⁺ >80% and lung homing markers, including CD49d. UCB Tregs did not turn pathogenic when exposed to IL-6. Co-culture with increasing doses of dexamethasone led to a synergistic increase in UCB Treg-induced apoptosis of conventional T cells (Tcons), which translated into significantly higher suppression of proliferating Tcons, especially at a lower Treg:Tcon ratio. Multiple injections of UCB Tregs led to their preferential accumulation in lung tissue in an immune injury xenogenic model. A significant decrease in lung resident cytotoxic CD8⁺ T cells (P = 0.0218) correlated with a sustained decrease in their systemic distribution compared with controls (P < 0.0001) (n = 7 per arm) as well as a decrease in circulating human soluble CD40 ligand level (P = 0.031). Tissue architecture was preserved in the treatment arm, and a significant decrease in CD3⁺ and CD8⁺ burden was evident in immunohistochemistry analysis.

CONCLUSIONS

UCB Treg adoptive therapy is a promising therapeutic strategy for treatment of lung injury.

Macrophage-derived exosome promotes regulatory T cell differentiation in malignant pleural effusion

Introduction

Tumor-associated macrophages are one of the key components of the tumor microenvironment. The immunomodulatory activity and function of macrophages in malignant pleural effusion (MPE), a special tumor metastasis microenvironment, have not been clearly defined.

Methods

MPE-based single-cell RNA sequencing data was used to characterize macrophages. Subsequently, the regulatory effect of macrophages and their secreted exosomes on T cells was verified by experiments. Next, miRNA microarray was used to analyze differentially expressed miRNAs in MPE and benign pleural effusion, and data from The Cancer Genome Atlas (TCGA) was used to evaluate the correlation between miRNAs and patient survival.

Results

Single-cell RNA sequencing data showed macrophages were mainly M2 polarized in MPE and had higher exosome secretion function compared with those in blood. We found that exosomes released from macrophages could promote the differentiation of naïve T cells into Treg cells in MPE. We detected differential expression miRNAs in macrophage-derived exosomes between MPE and benign pleural effusion by miRNA microarray and found that miR-4443 was significantly overexpressed in MPE exosomes. Gene functional enrichment analysis showed that the target genes of miR-4443 were involved in the regulation of protein kinase B signaling and lipid biosynthetic process.

Conclusions

Taken together, these results reveal that exosomes mediate the intercellular communication between macrophages and T cells, yielding an immunosuppressive environment for MPE. miR-4443 expressed by macrophages, but not total miR-4443, might serve as a prognostic marker in patients with metastatic lung cancer.

Extensive Phenotypic Characterization of T Cells Infiltrating Liver Metastasis from Colorectal Cancer: A Potential Role in Precision Medicine

Colorectal cancer (CRC) is one of the most common cancers worldwide, with liver metastasis being its main cause of death. This study harvested fresh biological material from non-tumor and tumor tissue from 47 patients with CRC liver metastasis after surgery, followed by mechanical cellular extraction and stain-lyse-wash direct immunofluorescence technique. Here, 60 different T-cell populations were characterized by flow cytometry. Tumor samples were also subdivided according to their growth pattern into desmoplastic and non-desmoplastic. When we compared tumor versus non-tumor samples, we observed a significantly lower percentage of T-lymphocyte infiltration in the tumor in which the CD4⁺ T-cell density increased compared to the CD8⁺ T cells. T regulatory cells also increased within the tumor, even with an activated phenotype (HLA-DR⁺). A higher percentage of IL-17-producing cells was present in tumor samples and correlated with the metastasis size. In contrast, we also observed a significant increase in CD8⁺ follicular-like T cells (CD185⁺), suggesting a cytotoxic response to cancer cells. Additionally, most infiltrated T cells exhibit an intermediate activation phenotype (CD25⁺). In conclusion, our results revealed potential new targets and prognostic biomarkers that could take part in an algorithm for personalized medicine approaches improving CRC patients' outcomes.

Chagasic cardiomyopathy is marked by a unique signature of activated CD4+ T cells

Chagas disease is a neglected tropical disease in Latin America and an imported emerging disease worldwide. Chronic Chagas disease cardiomyopathy (CCC) is the most prominent clinical form and can lead to heart failure, thromboembolism, and sudden death. While previous reports have supported a role for CD4⁺ T lymphocytes in the pathogenesis of CCC a comprehensive analysis of these cells during different clinical forms is lacking. Here, we used high-dimensional flow cytometry to assess the diversity of circulating CD4⁺ T cells in patients with distinct clinical forms. We found increased frequencies of CD4⁺CD69⁺ T cells in patients compared to controls. CD39⁺ regulatory T cells, represented by mesocluster 6 were reduced in mild CCC patients compared to controls. Cytotoxic CD4⁺ T cells co-expressing granzyme B and perforin were expanded in patients with Chagas disease and were higher in patients with mild CCC compared to controls. Furthermore, patients with mild CCC displayed higher frequencies of multifunctional effector memory CD4⁺ T cells. Our results demonstrate an expansion in activated CD4⁺ T cells and a decrease in a functional subset of regulatory T cells associated with the onset of Chagas cardiomyopathy, suggesting their role in the establishment of cardiac lesions and as potential biomarkers for disease aggravation.

Correlations between Circulating and Tumor-Infiltrating CD4+ Treg Subsets with Immune Checkpoints in Colorectal Cancer Patients with Early and Advanced Stages

The existence of various T regulatory cell (Treg) subsets in colorectal cancer (CRC) could play a variety of functions in the regulation of anti-cancer immunity. We studied correlations between CD4⁺ Treg subsets with the expression of immunological checkpoints on CD4⁺ T cells, including PD-1, TIM-3, LAG-3, and CTLA-4 in CRC patients with early and advanced TNM staging. Strong positive correlations were found between frequencies of FoxP3⁺ Tregs and FoxP3⁺Helios⁺ Tregs with frequencies of various immune checkpoint-expressing CD4⁺ T cells in the tumor microenvironment (TME). However, there were strong negative correlations between frequencies of FoxP3⁻Helios⁻ T cells and these immune checkpoint-expressing CD4⁺ T cells. Specifically, in the TME, we found that the correlations between FoxP3⁺ Tregs, FoxP3⁺Helios⁺ Tregs, FoxP3⁺Helios⁻ Tregs, and FoxP3⁻Helios⁻ T cells with CD4⁺LAG-3⁺ T cells and CD4⁺CTLA-4⁺ T cells were higher in patients with early stages, suggesting the potential of these highly immunosuppressive cells in inhibiting inflammatory responses in the TME. However, the correlations between FoxP3⁺ Tregs, FoxP3⁺Helios⁺ Tregs, and FoxP3⁻Helios⁻ T cells with CD4⁺TIM-3⁺ T cells were higher in patients with advanced stages. This is the first study to explore correlations of Treg subpopulations with immune checkpoint-expressing CD4⁺ T cells in CRC based on clinicopathological features of CRC patients. The findings of our study provide a justification for focusing on these cells that possess highly immunosuppressive features. Understanding the correlations between different immune checkpoints and Treg subsets in CRC patients has the potential to enhance our understanding of core mechanisms of Treg-mediated immunosuppression in cancer.

Associations of different immune checkpoints-expressing CD4+ Treg/ T cell subsets with disease-free survival in colorectal cancer patients

There are different subsets of T regulatory cells (Tregs), orchestrating critical roles in the regulation of anti-tumor immunity in colorectal cancer (CRC). In this study, we report that a high frequency of circulating CD4⁺FoxP3⁺ Tregs was associated with poorer disease-free survival (DFS), while their higher frequencies in tumor-infiltrating CD4⁺ Tregs was associated with better DFS. We further investigated such associations with four Tregs/T cells expressing or lacking FoxP3 and Helios (FoxP3^±Helios^±). For the first time, we report that a high frequency of circulating CD4⁺FoxP3⁺Helios⁺ Tregs was associated with poorer DFS, while a high frequency of tumor-infiltrating CD4⁺FoxP3⁻Helios⁻ T cells was associated with poorer DFS. In the four FoxP3^±Helios^± T cell subsets expressing any of the immune checkpoints (ICs) investigated, we found that a high frequency of CD4⁺FoxP3⁺Helios⁻PD-1⁺ Tregs in circulation was associated with worse DFS. We also found that high frequencies of FoxP3⁺Helios⁺CTLA-4⁺ Tregs, FoxP3⁺Helios⁻CTLA-4⁺ Tregs, and FoxP3⁻Helios⁺CTLA-4⁺ CD4⁺ T cells in circulation were associated with worse DFS. In contrast, high frequencies of CD4⁺TIM-3⁺ T cells, FoxP3⁺Helios⁺TIM-3⁺ Tregs, and FoxP3⁻Helios⁺TIM-3⁺ CD4⁺ T cells in circulation were associated with longer DFS. Our data show that certain CD4⁺ Treg/T cell subsets could serve as independent predictive biomarkers in CRC patients. Identification of the exact subpopulations contributing to clinical outcomes is critical for prognoses and therapeutic targeting.

Identification of the Shared Gene Signatures and Biological Mechanism in Type 2 Diabetes and Pancreatic Cancer

Background

The relationship between pancreatic cancer (PC) and type 2 diabetes mellitus (T2DM) has long been widely recognized, but the interaction mechanisms are still unknown. This study was aimed to investigate the shared gene signatures and molecular processes between PC and T2DM.

Methods

The Gene Expression Omnibus (GEO) database was used to retrieve the RNA sequence and patient information of PC and T2DM. Weighted gene co-expression network analysis (WGCNA) was performed to discover a co-expression network associated with PC and T2DM. Enrichment analysis of shared genes present in PC and T2DM was performed by ClueGO software. These results were validated in the other four cohorts based on differential gene analysis. The predictive significance of S100A6 in PC was evaluated using univariate and multivariate Cox analyses, as well as Kaplan-Meier plots. The biological process of S100A6 enrichment in PC was detected using Gene Set Enrichment Analysis (GSEA). The involvement of S100A6 in the tumor immune microenvironment (TIME) was assessed by CIBERSORT. In vitro assays were used to further confirm the function of S100A6 in PC.

Results

WGCNA recognized three major modules for T2DM and two major modules for PC. There were 44 shared genes identified for PC and T2DM, and Gene Ontology (GO) analysis showed that regulation of endodermal cell fate specification was primarily enriched. In addition, a key shared gene S100A6 was derived in the validation tests. S100A6 was shown to be highly expressed in PC compared to non-tumor tissues. PC patients with high S100A6 expression had worse overall survival (OS) than those with low expression. GSEA revealed that S100A6 is involved in cancer-related pathways and glycometabolism-related pathways. There is a strong relationship between S100A6 and TIME. In vitro functional assays showed that S100A6 helped to induce the PC cells' proliferation and migration. We also proposed a diagram of common mechanisms of PC and T2DM.

Conclusions

This study firstly revealed that the regulation of endodermal cell fate specification may be common pathogenesis of PC and T2DM and identified S100A6 as a possible biomarker and therapeutic target for PC and T2DM patients.

Correlations between Circulating and Tumor-Infiltrating CD4+ T Cell Subsets with Immune Checkpoints in Colorectal Cancer

T regulatory cells (Tregs) play different roles in the regulation of anti-tumor immunity in colorectal cancer (CRC), depending on the presence of different Treg subsets. We investigated correlations between different CD4+ Treg/T cell subsets in CRC patients with immune checkpoint-expressing CD4+ T cells. Positive correlations were observed between levels of different immune checkpoint-expressing CD4+ T cells, including PD-1, TIM-3, LAG-3, and CTLA-4 with FoxP3+ Tregs, Helios+ T cells, FoxP3+Helios+ Tregs, and FoxP3+Helios− Tregs in the tumor microenvironment (TME). However, negative correlations were observed between levels of these immune checkpoint-expressing CD4+ T with FoxP3−Helios− T cells in the TME. These correlations in the TME highlight the role of cancer cells in the upregulation of IC-expressing Tregs. Additionally, positive correlations were observed between levels of FoxP3+ Tregs, Helios+ T cells, FoxP3+Helios+ Tregs, and FoxP3+Helios− Tregs and levels of CD4+CTLA-4+ T cells and CD4+PD-1+ T cells in peripheral blood mononuclear cells (PBMCs) and normal tissue-infiltrating lymphocytes (NILs). These observations suggest that CTLA-4 and PD-1 expressions on CD4+ T cell subsets are not induced only by the TME. This is the first study to investigate the correlations of different FoxP3+/−Helios+/− T cell subsets with immune checkpoint-expressing CD4+ T cells in CRC patients. Our data demonstrated strong correlations between FoxP3+/Helios+/− Tregs but not FoxP3−Helios+/− non-Tregs and multiple immune checkpoints, especially in the TME, providing a rationale for targeting these cells with highly immunosuppressive characteristics. Understanding the correlations between different immune checkpoints and Treg/T cell subsets in cancer patients could improve our knowledge of the underlying mechanisms of Treg-mediated immunosuppression in cancer.

Targeting regulatory T cells in anti-PD-1/PD-L1 cancer immunotherapy

The programmed death (PD)-1/PD-ligand (PD-L) pathway and regulatory T cells (Tregs) are essential for the maintenance of immune tolerance. Their activation in the tumor microenvironment contributes to the evasion of the transformed cells from the immune surveillance and the suppression of an antitumor immune response. Therefore, PD-1/PD-L1 and Tregs are important targets for cancer immunotherapy. Our review focuses on the current role of the PD-1/PD-L1 axis in Treg development and function in the tumor microenvironment. We also discuss combination therapy with PD-1/PD-L1 inhibitors and Treg-modulating agents affecting the adenosinergic pathway, TGF-β signaling, immune checkpoints, and other approaches to downregulation of Tregs.

IRF4 is Correlated with the Conversion to a Th17-Like Phenotype in Regulatory T Cells from the Malignant Pleural Effusion

Background

RORγt⁺Foxp3⁺ (Th17-like) Tregs are a plastic Treg subset implicated in immune-related diseases; however, the mechanism of Treg phenotypic transformation in malignant pleural effusion (MPE) has not been elucidated.

Methods

The percentage of CD4⁺CD25⁺Foxp3⁺Helios⁺ and RORγt⁺Foxp3⁺ Tregs from peripheral blood and pleural effusion mononuclear cells were measured. The level of interferon regulatory factor 4 (IRF4) mRNA expression was detected by quantitative real-time reverse transcription polymerase chain reaction. The effects of IRF4 on the induction of Tregs from patients with non-small cell lung cancer (NSCLC) were evaluated in vitro. Correlation assays between IRF4 expression and the frequency of RORγt⁺Foxp3⁺ Tregs were performed.

Results

The frequency of CD4⁺CD25⁺Foxp3⁺Helios⁺ Tregs and CD4⁺RORγt⁺ Th17 cells was both increased in the MPE of NSCLC patients. The group of double-positive Foxp3⁺RORγt⁺ Treg phenotype were identified in the pleural effusion. A significant increase in the frequency of Foxp3⁺RORγt⁺ Tregs was found in MPE compared with the non-malignant pleural effusion (NPE). Compared to NPE, the relative level of IRF4 expression was increased in the MPE. IRF4 expression was positively associated with the frequency of Foxp3⁺RORγt⁺ Tregs in the PE. In vitro, the level of Helios mRNA and protein expression was reduced in induced Tregs following IRF4 over-expression. Additionally, the level of RORγt protein expression was substantially increased. However, ectopic Helios expression in induced Tregs reversed the effects induced by enhanced IRF4 expression.

Conclusion

IRF4 may serve as a potential molecule that promotes the conversion of regulatory T cells from MPE to a Th17-like phenotype by modulating Helios.

Emerging Complexity in CD4+T Lineage Programming and Its Implications in Colorectal Cancer

The intestinal immune system has the difficult task of protecting a large environmentally exposed single layer of epithelium from pathogens without allowing inappropriate inflammatory responses. Unmitigated inflammation drives multiple pathologies, including the development of colorectal cancer. CD4⁺T cells mediate both the suppression and promotion of intestinal inflammation. They comprise an array of phenotypically and functionally distinct subsets tailored to a specific inflammatory context. This diversity of form and function is relevant to a broad array of pathologic and physiologic processes. The heterogeneity underlying both effector and regulatory T helper cell responses to colorectal cancer, and its impact on disease progression, is reviewed herein. Importantly, T cell responses are dynamic; they exhibit both quantitative and qualitative changes as the inflammatory context shifts. Recent evidence outlines the role of CD4⁺T cells in colorectal cancer responses and suggests possible mechanisms driving qualitative alterations in anti-cancer immune responses. The heterogeneity of T cells in colorectal cancer, as well as the manner and mechanism by which they change, offer an abundance of opportunities for more specific, and likely effective, interventional strategies.

Intratumoral regulatory T cells from colon cancer patients comprise several activated effector populations

Background

Intratumoral regulatory T cells (Treg) in colon cancer are a heterogeneous cell population, with potential impact on patient outcome. Generally, a high Treg infiltration has been correlated to a worse patient outcome, but it is still unclear how the composition of different Treg subsets affects patient relapse and survival. In this study, we used mass and flow cytometry to characterize Treg in colon tumors and corresponding unaffected tissue, followed by a correlation to clinical parameters and patient outcome.

Results

Using mass cytometry, we defined 13 clusters of intestinal Treg, three of which were enriched in the tumors. The two most enriched clusters were defined by their expression of the proliferation marker Ki67 and CD56, respectively. The Treg accumulating in the tumors expressed inducible T-cell co-stimulator (ICOS), OX-40, and CD39, indicating that they were effector Treg (eTreg). Intratumoral CD39⁺ Treg also had a higher expression of Foxp3, suggesting a higher suppressive activity, and we subsequently used CD39 as a marker for eTreg. Our further studies showed that colon tumors can be divided into two tumor groups, based on the proportion of CD39⁺ putative eTreg in the tumors. This property was independent of both tumor microsatellite status and tumor stage, which are important factors in predicting cancer disease progression. In a prospective study of forty-four colon cancer patients, we also showed that patients with a high CD39 expression on tumor-infiltrating Treg have a tendency towards a less favorable patient outcome in terms of cumulative cancer-specific survival.

Conclusions

This study uncovers novel subsets of tumor-infiltrating Treg in colon cancer, and suggests that CD39 may be a potential therapeutic target in patients with microsatellite stable colon tumors, which are usually refractory to checkpoint blockade therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-021-00449-1.

CD39 Regulation and Functions in T Cells

CD39 is an enzyme which is responsible, together with CD73, for a cascade converting adenosine triphosphate into adenosine diphosphate and cyclic adenosine monophosphate, ultimately leading to the release of an immunosuppressive form of adenosine in the tumor microenvironment. Here, we first review the environmental and genetic factors shaping CD39 expression. Second, we report CD39 functions in the T cell compartment, highlighting its role in regulatory T cells, conventional CD4⁺ T cells and CD8⁺ T cells. Finally, we compile a list of studies, from preclinical models to clinical trials, which have made essential contributions to the discovery of novel combinatorial approaches in the treatment of cancer.

Hsa_circ_0136666 activates Treg-mediated immune escape of colorectal cancer via miR-497/PD-L1 pathway

PURPOSE

In the rankings of cancer mortality and incidence worldwide, colorectal cancer ranks fourth and the third, respectively. Circular RNA hsa_circ_0136666 (hsa_circ_0136666) is reported to participate in the growth of colorectal cancer. However, the mechanism by which hsa_circ_0136666 regulates the tumorigenesis of colorectal cancer needs to be further explored. In this study, we report here the role of hsa_circ_0136666 in the aberrant activation of Treg cells and immune evasion of tumor cells, providing a new strategy for the treatment of colorectal cancer.

METHODS

Western blotting assay and qRT-PCR assay were used to determine protein and mRNA expression levels. Dual-luciferase reporter assay was used to evaluate the targeted regulatory relationship. RNA immunoprecipitation was used to detect RNA binding. Colony formation assay was utilized to measure the cell proliferation. Flow cytometry was used to assess cell apoptosis. Xenograft model was setup to evaluate tumor growth.

RESULTS

The results showed that hsa_circ_0136666 and PD-L1 was increased in colorectal cancer cells while miR-497 was decreased in colorectal cancer cells when compared with normal colon epithelial cell line. Hsa_circ_0136666 was demonstrated to directly target miR-497, which also regulated PD-L1 by binding to its 3'UTR. Further mechanistic studies identified that hsa_circ_0136666 controlled cell proliferation and apoptosis via targeting miR-497 and regulating PD-L1 expression. Of note, hsa_circ_0136666 stimulated Treg cells mediated by miR-497/PD-L1 axis and its downstream signal pathway in Treg cells. Finally, hsa_circ_0136666 was found to accelerate the tumor growth in vivo.

CONCLUSIONS

Our findings demonstrated that hsa_circ_0136666 promoted the expression of PD-L1 by inhibiting miR-497 level in colorectal cancer, thus inducing the activation of Treg cells and leading to the immune escape of tumor, providing a novel mechanistic insight into the pathogenesis of colorectal cancer.

SERPINE1 associated with remodeling of the tumor microenvironment in colon cancer progression: a novel therapeutic target

Background

The change of immune cell infiltration essentially influences the process of colorectal cancer development. The infiltration of immune cells can be regulated by a variety of genes. Thus, modeling the immune microenvironment of colorectal cancer by analyzing the genes involved can be more conducive to the in-depth understanding of carcinogenesis and the progression thereof.

Methods

In this study, the number of stromal and immune cells in malignant tumor tissues were first estimated by using expression data (ESTIMATE) and cell-type identification with relative subsets of known RNA transcripts (CIBERSORT) to calculate the proportion of infiltrating immune cell and stromal components of colon cancer samples from the Cancer Genome Atlas database. Then the relationship between the TMN Classification and prognosis of malignant tumors was evaluated.

Results

By investigating differentially expressed genes using COX regression and protein-protein interaction network (PPI), the candidate hub gene serine protease inhibitor family E member 1 (SERPINE1) was found to be associated with immune cell infiltration. Gene Set Enrichment Analysis (GSEA) further projected the potential pathways with elevated SERPINE1 expression to carcinogenesis and immunity. CIBERSORT was subsequently utilized to investigate the relationship between the expression differences of SERPINE1 and immune cell infiltration and to identify eight immune cells associated with SERPINE1 expression.

Conclusion

We found that SERPINE1 plays a role in the remodeling of the colon cancer microenvironment and the infiltration of immune cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08536-7.

Coexpression of Helios in Foxp3+ Regulatory T Cells and Its Role in Human Disease

Regulatory T cells (Tregs) expressing the Foxp3 transcription factor are indispensable for the maintenance of immune system homeostasis. Tregs may lose Foxp3 expression or be reprogrammed into cells that produce proinflammatory cytokines, for example, Th1-like Tregs, Th2-like Tregs, Th17-like Tregs, and Tfh-like Tregs. Accordingly, selective therapeutic molecules that manipulate Treg lineage stability and/or functional activity might have the potential to improve aberrant immune responses in human disorders. In particular, the transcription factor Helios has emerged as an important marker and modulator of Tregs. Therefore, the current review focuses on recent findings on the expression, function, and mechanisms of Helios, as well as the patterns of Foxp3⁺ Tregs coexpressing Helios in various human disorders, in order to explore the potential of Helios for the improvement of many immune-related diseases. The studies were selected from PubMed using the library of the Nanjing Medical University in this review. The findings of the included studies indicate that Helios expression stabilizes the phenotype and function of Foxp3⁺ Tregs in certain inflammatory environments. Further, Tregs coexpressing Helios and Foxp3 were identified as a specific phenotype of stronger suppressor immune cells in both humans and animal models. Importantly, there is ample evidence that Helios-expressing Foxp3⁺ Tregs are relevant to various human disorders, including connective tissue diseases, infectious diseases, solid organ transplantation-related immunity, and cancer. Thus, Helios⁺Foxp3⁺CD4⁺ Tregs could be a valuable target in human diseases, and their potential should be explored further in the clinical setting.

RNA Flow Cytometry for the Study of T Cell Metabolism

T cells undergo activation and differentiation programs along a continuum of states that can be tracked through flow cytometry using a combination of surface and intracellular markers. Such dynamic behavior is the result of transcriptional and post-transcriptional events, initiated and sustained by the activation of specific transcription factors and by epigenetic remodeling. These signaling pathways are tightly integrated with metabolic routes in a bidirectional manner: on the one hand, T cell receptors and costimulatory molecules activate metabolic reprogramming; on the other hand, metabolites modify T cell transcriptional programs and functions. Flow cytometry represents an invaluable tool to analyze the integration of phenotypical, functional, metabolic and transcriptional features, at the single cell level in heterogeneous T cell populations, and from complex microenvironments, with potential clinical application in monitoring the efficacy of cancer immunotherapy. Here, we review the most recent advances in flow cytometry-based analysis of gene expression, in combination with indicators of mitochondrial activity, with the aim of revealing and characterizing major metabolic pathways in T cells.

Profiles of immune infiltration and its relevance to survival outcome in meningiomas

Tumor-infiltrating immune cells play a decisive part in prognosis and survival. Until now, previous researches have not made clear about the diversity of cell types involved in the immune response. The objective of this work was to confirm the composition of tumor-infiltrating immune cells and their correlation with prognosis in meningiomas based on a metagene approach (known as CIBERSORT) and online databases. A total of 22 tumor-infiltrating immune cells were detected to determine the relationship between the immune infiltration pattern and survival. The proportion of M2 macrophages was more abundant in 68 samples, reaching more than 36%. Univariate Cox regression analysis displayed that the proportion of dendritic cells was obviously related to prognosis. Hierarchical clustering analysis identified two clusters by the method of within sum of squares errors, which exhibited different infiltrating immune cell composition and survival. To summarize, our results indicated that proportions of tumor-infiltrating immune cells as well as cluster patterns were associated with the prognosis, which offered clinical significance for research of meningiomas.

PARASITIC ABSCESS AS AN INCIDENTAL HISTOLOGICAL FINDING IN THE TREATMENT OF SIGMOID COLON CANCER

Background: A high worldwide incidence of colorectal cancer defines the importance of search not only for effective treatment methods, but also for risk factors for the cancer development and its worst prognosis. The influence of many genetic factors, environmental characteristics and lifestyle features has already been proven, and recently the attention of researchers is being focused on the study of microbiota and, in particular, various parasitic intestinal diseases in the context of risk factors for colorectal cancer.Clinical case presentation: we demonstrate an incidental finding of parasitic invasion signs during the pathomorphological examination of the surgical specimen in a patient without an epidemiological history.Conclusion: Further studies are needed not only to confirm and substantiate the role of micro- and macroorganisms inhabiting the intestine in the development of oncological diseases, but also to identify individual links of pathogenesis, pathological pathways and signaling molecules involved in carcinogenesis. Research like this could help broaden knowledge about both the risk factors and predictors of colorectal cancer and the potential sites for targeted therapy.

Immunometabolism of regulatory T cells in cancer

Regulatory T (Treg) cells are known to orchestrate the regulatory mechanisms aimed at suppressing pathological auto-reactive immune responses and are thus key in ensuring the maintenance of immune homeostasis. On the other hand, the presence of Treg cells with enhanced suppressive capability in a plethora of human cancers represents a major obstacle to an effective anti-cancer immune response. A relevant research effort has thus been dedicated to comprehend Treg cell biology, leading to a continuously refining characterization of their phenotype and function and unveiling the central role of metabolism in ensuring Treg cell fitness in cancer. Here we focus on how the peculiar biochemical characteristics of the tumor microenvironment actually support Treg cell metabolic activation and favor their selective survival and proliferation. Moreover, we examine the key metabolic pathways that may become useful targets of novel treatments directed at hampering tumor resident Treg cell proficiency, thus representing the next research frontier in cancer immunotherapy.

OX40 Agonist BMS-986178 Alone or in Combination With Nivolumab and/or Ipilimumab in Patients With Advanced Solid Tumors

PURPOSE

This phase I/IIa study (NCT02737475) evaluated the safety and activity of BMS-986178, a fully human OX40 agonist IgG1 mAb, ± nivolumab and/or ipilimumab in patients with advanced solid tumors.

PATIENTS AND METHODS

Patients (with non-small cell lung, renal cell, bladder, other advanced cancers) received BMS-986178 (20-320 mg) ± nivolumab (240-480 mg) and/or ipilimumab (1-3 mg/kg). The primary endpoint was safety. Additional endpoints included immunogenicity, pharmacodynamics, pharmacokinetics, and antitumor activity per RECIST version 1.1.

RESULTS

Twenty patients received BMS-986178 monotherapy, and 145 received combination therapy in various regimens (including two patients receiving nivolumab monotherapy). With a follow-up of 1.1 to 103.6 weeks, the most common (≥5%) treatment-related adverse events (TRAEs) included fatigue, pruritus, rash, pyrexia, diarrhea, and infusion-related reactions. Overall, grade 3-4 TRAEs occurred in one of 20 patients (5%) receiving BMS-986178 monotherapy, six of 79 (8%) receiving BMS-986178 plus nivolumab, zero of two receiving nivolumab monotherapy, six of 41 (15%) receiving BMS-986178 plus ipilimumab, and three of 23 (13%) receiving BMS-986178 plus nivolumab plus ipilimumab. No deaths occurred. No dose-limiting toxicities were observed with monotherapy, and the MTD was not reached in either the monotherapy or the combination escalation cohorts. No objective responses were seen with BMS-986178 alone; objective response rates ranged from 0% to 13% across combination therapy cohorts.

CONCLUSIONS

In this study, BMS-986178 ± nivolumab and/or ipilimumab appeared to have a manageable safety profile, but no clear efficacy signal was observed above that expected for nivolumab and/or ipilimumab.

Antiangiogenic immunotherapy suppresses desmoplastic and chemoresistant intestinal tumors in mice

Mutations in APC promote colorectal cancer (CRC) progression through uncontrolled WNT signaling. Patients with desmoplastic CRC have a significantly worse prognosis and do not benefit from chemotherapy, but the mechanisms underlying the differential responses of APC-mutant CRCs to chemotherapy are not well understood. We report that expression of the transcription factor prospero homeobox 1 (PROX1) was reduced in desmoplastic APC-mutant human CRCs. In genetic Apc-mutant mouse models, loss of Prox1 promoted the growth of desmoplastic, angiogenic, and immunologically silent tumors through derepression of Mmp14. Although chemotherapy inhibited Prox1-proficient tumors, it promoted further stromal activation, angiogenesis, and invasion in Prox1-deficient tumors. Blockade of vascular endothelial growth factor A (VEGFA) and angiopoietin-2 (ANGPT2) combined with CD40 agonistic antibodies promoted antiangiogenic and immunostimulatory reprogramming of Prox1-deficient tumors, destroyed tumor fibrosis, and unleashed T cell-mediated killing of cancer cells. These results pinpoint the mechanistic basis of chemotherapy-induced hyperprogression and illustrate a therapeutic strategy for chemoresistant and desmoplastic CRCs.

An update on colorectal cancer microenvironment, epigenetic and immunotherapy

Colorectal cancer (CRC) is considered as the second most common cancer worldwide. For the past few years, the role of immunotherapy has been extensively studied and it has been demonstrated that its related approaches, such as programmed death-1 (PD-1) inhibitors, are promising. In addition to identifying molecular characteristics of tumor cells, recent studies are mainly focused on the profiling of tumor microenvironment. Dissecting immune status of a tumor is interesting, since development of a tumor is associated with deficiencies relate to immune defense, immune surveillance and immune hemostasis. In this review, we discuss main obstacles of immunotherapy including immunosuppressive niche and low immunogenicity of CRC as well as reviewing current achievements in immunotherapy.

G-CSF and G-CSFR Modulate CD4 and CD8 T Cell Responses to Promote Colon Tumor Growth and Are Potential Therapeutic Targets

Cytokines are known to shape the tumor microenvironment and although progress has been made in understanding their role in carcinogenesis, much remains to learn regarding their role in tumor growth and progression. We have identified granulocyte colony-stimulating factor (G-CSF) as one such cytokine, showing that G-CSF is linked with metastasis in human gastrointestinal tumors and neutralizing G-CSF in a mouse model of colitis-associated cancer is protective. Here, we set out to identify the role of G-CSF and its receptor, G-CSFR, in CD4⁺ and CD8⁺ T cell responses in the tumor microenvironment. MC38 colon cancer cells were injected into WT, G-CSFR^-/- mice, or Rag2^-/- mice. Flow cytometry, Real Time PCR and Multiplex cytokine array analysis were used for in vitro T cell phenotype analysis. Adoptive transfer of WT or G-CSFR^-/- CD4⁺ of CD8⁺ T cells were performed. Mouse tumor size, cytokine expression, T cell phenotype, and cytotoxic activity were analyzed. We established that in G-CSFR^-/- mice, tumor growth of MC38 colon cancer cells is significantly decreased. T cell phenotype and cytokine production were also altered, as both in vitro and in vivo approaches revealed that the G-CSF/G-CSFR stimulate IL-10-producing, FoxP3-expressing CD4⁺ and CD8⁺ T cells, whereas G-CSFR^-/- T cells exhibit increased IFNγ and IL-17A production, leading to increased cytotoxic activity in the tumor microenvironment. Furthermore, peritumoral injection of recombinant IFNγ or IL-17A inhibited colon and pancreas tumor growth compared to controls. Taken together, our data reveal an unknown mechanism by which G-CSF, through its receptor G-CSFR, promotes an inhibitory Treg phenotype that limits tumor immune responses and furthermore suggest that targeting this cytokine/receptor axis could represent a novel therapeutic approach for gastrointestinal, and likely other tumors with high expression of these factors.

Alterations in the Gut Microbiome and Suppression of Histone Deacetylases by Resveratrol Are Associated with Attenuation of Colonic Inflammation and Protection Against Colorectal Cancer

Inflammatory bowel disease (IBD) is known to significantly increase the risk for development of colorectal cancer (CRC), suggesting inflammation and cancer development are closely intertwined. Thus, agents that suppress inflammation may prevent the onset of cancer. In the current study, we used resveratrol, an anti-inflammatory stilbenoid, to study the role of microbiota in preventing inflammation-driven CRC. Resveratrol treatment in the azoxymethane (AOM) and dextran sodium sulphate (DSS) CRC murine model caused an increase in anti-inflammatory CD4 + FOXP3 + (Tregs) and CD4 + IL10 + cells, a decrease in proinflammatory Th1 and Th17 cells, and attenuated CRC development. Gut microbial profile studies demonstrated that resveratrol altered the gut microbiome and short chain fatty acid (SCFA), with modest increases in n-butyric acid and a potential butyrate precursor isobutyric acid. Fecal transfer from resveratrol-treated CRC mice and butyrate supplementation resulted in attenuation of disease and suppression of the inflammatory T cell response. Data also revealed both resveratrol and sodium butyrate (BUT) were capable of inhibiting histone deacetylases (HDACs), correlating with Treg induction. Analysis of The Cancer Genome Atlas (TCGA) datasets revealed increased expression of Treg-specific transcription factor FoxP3 or anti-inflammatory IL-10 resulted in an increase in 5-year survival of patients with CRC. These data suggest that alterations in the gut microbiome lead to an anti-inflammatory T cell response, leading to attenuation of inflammation-driven CRC.

Pattern of immune infiltration in lung cancer and its clinical implication

BACKGROUND

Tumor-infiltrating immune cells play an essential role in prognosis and survival after therapy. However, previous works have not made clear about the diversity of distinct cell types that participate in the immune response. We determined the composition of tumor-infiltrating immune cells and their correlation with prognosis in lung cancer based on a metagene approach (known as CIBERSORT) and online databases.

METHODS

A total of 22 tumor-infiltrating immune cells were estimated to confirm the associations between the immune infiltration pattern and survival. As a result, the proportions of activated NK cell, monocytes, M0 macrophages and M1 macrophages in 56 cancer samples were significantly higher than those in 56 paracancerous samples.

RESULTS

Univariate Cox regression analysis displayed that the proportions of NK cell and monocytes were significantly associated with prognosis. Hierarchical clustering analysis predicted five clusters by the method of within sum of squares errors (wss), which exhibited different infiltrating immune cell composition and prognosis.

CONCLUSIONS

The proportions of tumor-infiltrating immune cells as well as cluster patterns were associated with the prognosis, which provided potential therapeutic targets for lung cancer.

Interferon-α2b enhances survival and modulates transcriptional profiles and the immune response in melanoma patients treated with dendritic cell vaccines

Malignant melanoma (MM) is the most lethal cutaneous cancer and is associated with 80 % of skin cancer deaths. Recent progress into elucidating the role of the immune system in melanoma development and progression has led to promising treatments for patients with MM, including dendritic cell (DC) vaccination. Interferon-α2b is a commonly used adjuvant for MM that prolongs overall survival (OS) and progression-free survival (PFS). In the present study, we examined the impact of a DC-based vaccine with subsequent delivery of high-dose systemic interferon-α2b (HDI) on gene expression profiles and the immune response in MM patients. The results indicated that patients who were randomized to receive an HDI boost following DC vaccination had significantly higher OS and PFS rates compared with patients that received DC vaccination alone. Further analysis revealed that intradermal DC immunization did not significantly alter transcriptional profiles, whereas subsequent HDI injections enhanced B cell, T cell and natural killer cell-related gene expression. Analysis of the abundance of tumor-infiltrating immune cells revealed that HDI altered the immune cell profiles. Moreover, we determined that follicular helper T (Tfh) cells and eosinophils were associated with prolonged PFS in MM patients treated with the DC vaccine.

High miR-31-5p expression promotes colon adenocarcinoma progression by targeting TNS1

Overexpression of the miR-31-5p contributes to tumorigenesis and metastasis in diverse neoplasms. In this study, we evaluated expression of miR-31-5p in patients with colon adenocarcinoma (COAD). We found that miR-31-5p was overexpressed in four cohorts (GSE30454, GSE41655, GSE18392, GSE108153) of COAD patients. Importantly, a LinkedOmics analysis revealed that high miR-31-5p expression was associated with poor overall survival of COAD patients. At total of 133 putative target genes of miR-31-5p were identified from TargetScan, miRDB, and TargetMiner. After integrating the target genes with 1,556 deregulated genes in COAD, 8 were acquired that may be targeted by miR-31-5p and contribute to COAD progression. Among these, tensin 1 (TNS1) showed the greatest prognostic ability in COAD and was strongly correlated with M2 macrophages, regulatory T cells, and other immune cells. These findings indicate that, in COAD, miR-31-5p is a potential prognostic factor that affects immune infiltration by targeting TNS1.

A single-nucleotide polymorphism in the human ENTPD1 gene encoding CD39 is associated with worsened graft-versus-host disease in a humanized mouse model

Regulatory T cells (Tregs) protect against graft-versus-host disease (GVHD), a life-threatening complication of allogeneic hematopoietic stem cell transplantation. The ectoenzyme CD39 is important for increasing the immunosuppressive function of Tregs. The rs10748643 (A → G) single-nucleotide polymorphism (SNP) in intron 1 of the human ENTPD1 gene is associated with increased proportions of CD39⁺ Tregs. This study aimed to determine whether the rs10748643 SNP corresponded to increased proportions of CD39⁺ Tregs in an Australian donor population, and whether this SNP influences clinical GVHD in a humanized mouse model. Donors were genotyped for the rs10748643 SNP by Sanger sequencing, and the proportion of CD39⁺ T cells in donor peripheral blood was determined by flow cytometry. Donors encoding the G allele (donors^AG/GG ) demonstrated higher proportions of CD39⁺ CD3⁺ CD4⁺ CD25⁺ CD127^lo Tregs, but not CD39⁺ CD3⁺ CD8⁺ T cells or CD39⁺ CD3⁺ CD4⁺ conventional T cells, compared with donors homozygous for the A allele (donors^AA ). NOD-SCID-IL2Rγ^null mice were injected with human peripheral blood mononuclear cells from either donors^AA (hCD39^AA mice) or donors^AG/GG (hCD39^AG/GG mice). hCD39^AG/GG mice demonstrated significantly greater weight loss and GVHD clinical scores, and significantly reduced survival, compared with hCD39^AA mice. hCD39^AG/GG mice showed significantly higher hCD4⁺ :hCD8⁺ T-cell ratios than hCD39^AA mice, but displayed similar proportions of CD3⁺ hCD4⁺ hCD25⁺ hCD127^lo Tregs and hCD39⁺ Tregs. However, the proportion of human Tregs corresponded to survival in hCD39^AA mice, but not in hCD39^AG/GG mice. This study demonstrates that donors encoding the G allele show higher percentages of CD39⁺ Tregs, but cause worsened GVHD in humanized mice compared with donors homozygous for the A allele.

Downregulation of miR-4772-3p promotes enhanced regulatory T cell capacity in malignant pleural effusion by elevating Helios levels

Background:

Malignant pleural effusion (MPE) is a complicated condition of patients with advanced tumors. Further dissecting the microenvironment of infiltrated immune cells and malignant cells are warranted to understand the immune-evasion mechanisms of tumor development and progression.

Methods:

The possible involvement of microRNAs (miRNAs) in malignant pleural fluid was investigated using small RNA sequencing. Regulatory T cell (Treg) markers (CD4, CD25, forkhead box P3), and Helios (also known as IKAROS Family Zinc Finger 2 [IKZF2]) were detected using flow cytometry. The expression levels of IKZF2 and miR-4772-3p were measured using quantitative real-time reverse transcription polymerase chain reaction. The interaction between miR-4772-3p and Helios was determined using dual-luciferase reporter assays. The effects of miR-4772-3p on Helios expression were evaluated using an in vitro system. Correlation assays between miR-4772-3p and functional molecules of Tregs were performed.

Results:

Compared with non-malignant controls, patients with non-small cell lung cancer had an increased Tregs frequency with Helios expression in the MPE and peripheral blood mononuclear cells. The verified downregulation of miR-4772-3p was inversely related to the Helios⁺ Tregs frequency and Helios expression in the MPE. Overexpression of miR-4772-3p could inhibit Helios expression in in vitro experiments. However, ectopic expression of Helios in induced Tregs reversed the effects induced by miR-4772-3p overexpression. Additionally, miR-4772-3p could regulate Helios expression by directly targeting IKZF2 mRNA.

Conclusion:

Downregulation of miR-4772-3p, by targeting Helios, contributes to enhanced Tregs activities in the MPE microenvironment.

Effects of fucoidan on gut flora and tumor prevention in 1,2-dimethylhydrazine-induced colorectal carcinogenesis

Colorectal cancer (CRC) is one of the major malignancies in humans. This study was designed to evaluate the effects of fucoidan on gut flora and tumor prevention in 1,2-dimethylhydrazine-induced colorectal carcinogenesis in rats. We found that dietary fucoidan treatment decreased the tumor incidence and mean tumor weight and increased cell apoptosis. Fucoidan treatment decreased the expression of β-catenin C-Myc, CyclinD1 and Survivin, while the Hippo pathway was activated with increased phosphorylation levels of mammalian sterile 20-like kinase 1 and 2, large tumor suppressor 1 and 2, and Yes-associated protein. Compared with the model group, the levels of interleukin (IL)-17 and IL-23 were decreased, but the levels of interferon-γ, IL-4 and IL-10 were increased, in the fucoidan group. Fucoidan treatment increased natural killer cells in peripheral blood and the proportion of CD4+ T cells. Immunofluorescence detection of colorectal tumor tissues showed decreased expression of Foxp3 and up-regulated expression of CD68 in the fucoidan group. Moreover, fucoidan treatment decreased the levels of diamine oxidase and lipopolysaccharides and up-regulated the levels of tight junction proteins. 16S rDNA high-throughput sequencing revealed that fucoidan treatment decreased the abundance of Prevotella and increased the abundance of Alloprevotella. Fucoidan increased the levels of butyric acid and valeric acid compared to the model group. This study provides experimental evidence that dietary fucoidan may prevent colorectal tumorigenesis by regulating gut microecology and body immunity. Meanwhile, fucoidan activated the Hippo pathway and down-regulated the β-catenin pathway to induce tumor cell apoptosis and suppress tumor growth.

Regulatory T cells specifically suppress conventional CD8αβ T cells in intestinal tumors of APCMin/+ mice

The presence of activated T cells in colorectal cancer tissues is a strong predictor of patient survival. Our previous studies have shown that regulatory T cells (Treg) are able to reduce T cell transendothelial migration in vitro and accumulation of effector T cells in intestinal tumors in vivo in the murine APC^Min/+ model for microsatellite stable intestinal tumors. In this study, we investigated the effect of Treg depletion on the density and effector functions of different TCRαβ⁺ and TCRγδ⁺ T cell populations in intestinal tumors. We used the APC^Min/+\DEREG mouse model, which harbor a diphtheria toxin receptor under the control of the FOXP3 promoter, to deplete Treg in tumor bearing mice. We found that the density of conventional TCRαβ⁺CD8αβ⁺ T cells was significantly increased in Treg-depleted tumors in comparison with Treg-proficient tumors. Furthermore, TCRαβ⁺CD8αβ⁺ T cells showed increased proliferation and activation as well as increased Granzyme B and IFN-γ production in Treg-depleted tumors. In sharp contrast, the densities and effector functions of TCRαβ⁺CD8αα⁺ T cells and TCRγδ⁺ T cells remained unchanged by Treg depletion. We also documented a distinct population of IL-17A⁺TNF⁺ TCRγδ⁺CD8⁻ T cells in tumors, which were not affected by Treg depletion. We conclude that Treg depletion affects only conventional TCRαβ⁺CD8αβ⁺ T cells in intestinal tumors, while unconventional T cells and T cells in unaffected tissue are not altered. Immunotherapies aimed at depleting Treg from tumors may thus be a viable option for reinvigoration of conventional cytotoxic T cells with a Th1 cytokine profile.

Relationships Between Immune Landscapes, Genetic Subtypes and Responses to Immunotherapy in Colorectal Cancer

Colorectal cancer (CRC) is highly heterogeneous at the genetic and molecular level, which has major repercussions on the efficacy of immunotherapy. A small subset of CRCs exhibit microsatellite instability (MSI), a molecular indicator of defective DNA mismatch repair (MMR), but the majority are microsatellite-stable (MSS). The high tumor mutational burden (TMB) and neoantigen load in MSI tumors favors the infiltration of immune effector cells, and antitumor immune responses within these tumors are strong relative to their MSS counterparts. MSI has emerged as a major predictive marker for the efficacy of immune checkpoint blockade over the last few years and nivolumab or pembrolizumab targeting PD-1 has been approved for patients with MSI refractory or metastatic CRC. However, some MSS tumors show DNA polymerase epsilon (POLE) mutations that also confer a very high TMB and may also be heavily infiltrated by immune cells making them amenable to respond to immune checkpoint inhibitors (ICI). In this review we discuss the role of the different immune landscapes in CRC and their relationships with defined CRC genetic subtypes. We discuss potential reasons why immune checkpoint blockade has met with limited success for the majority of CRC patients, despite the finding that immune cell infiltration of primary non-metastatic tumors is a strong predictive, and prognostic factor for relapse and survival. We then consider in which ways CRC cells develop mechanisms to resist ICI. Finally, we address the latest advances in CRC vaccination and how a personalized neoantigen vaccine strategy might overcome the resistance of MSI and MSS tumors in patients for whom immune checkpoint blockade is not a treatment option.

T follicular helper and T follicular regulatory cells in colorectal cancer: A complex interplay

Colorectal cancer is considered to be one of the major causes of morbidity and mortality all over the world. T Follicular helper (T_FH) and T follicular regulatory (T_FR) cells are specialized providers of T-cells to help B-cells and shaping germinal centers (GC) response. Recent researches reported a high percentage of T_FH and T_FR in different infectious diseases and certain malignancies. However, their functional role in human colorectal cancer (CRC) is relatively unknown. Furthermore, recent studies show that the interaction of both T_FH cells and T_FR cells are essential to promote several diseases. Under the control of specific cytokines and B-cell lymphoma 6 transcription factor (Bcl-6), the major transcription factor of T_FH cells, T_FH, can expand to the other distinct CD4 + T helper cells (TH1, TH2, and TH17) which exert a different role in the development of CRC. This review aims to discuss these suggested roles of the two-opposite subset of follicular T cells in colorectal cancer immune pathogenesis.

Advances in patent applications related to cancer vaccine using CpG-ODN and OX40 association

Introduction: This review aims to assess the available technologies, advances, and trends from technological readiness level 4 to level 8 for cancer immunologic therapeutics using the association of OX40 and CPG-ODN, usually known as cancer vaccine.Areas covered: Patent documents and clinic studies referring to the use of CpG-ODN and of OX40 association for cancer therapeutics. Patent data were obtained within the worldwide basis of the European Patent Office (EPO). The 138 patents of 36 patent families found were analyzed focusing on word distribution of technology developers and potential markets, legal status, annual evolution of first priority, technological domains, applicants and co-applicants and detailed analysis of each technology. Two clinical studies are in progress.Expert opinion: Traditional methods in post cancer diagnosis are being replaced by immunological association therapies. It is expected that the development of cancer vaccines will expand the scope of cancer-specific immunotherapy, especially if associated with alternative systems for expression and delivery with future potential. It is expected that genetic and controlled and/or specific nano delivery are improved. Furthermore, these new developments will likely address the problem of long-term treatments, reducing cancer mortality and reducing patient numbers worldwide.

Schistosoma japonicum-Associated Colorectal Cancer: A Review

Schistosoma japonicum is a digenetic blood fluke that has been implicated in the carcinogenesis of several human malignancies, notably liver and colorectal cancer (CRC). Schistosoma japonicum-associated colorectal cancer (SACC) is a distinct subtype with biological behavior analogous to colitis-induced CRC. The clinicopathological characteristics of SACC include young age at diagnosis, predominance among males, a strong predilection for the sigmoid colon and rectum, multifocal distribution, frequent mucinous histology, and poor prognosis. In addition to chronic inflammation, immunomodulation, and schistosomal toxins, bacterial coinfection appears to play an important role in the carcinogenic process. The present review provides the most recent updates on epidemiology, pathobiology, and clinical and prognostic features pertaining to SACC.

Tumor-Infiltrating Immune Cells Act as a Marker for Prognosis in Colorectal Cancer

Tumor-infiltrating immune cells (TIICs) play essential roles in cancer development and progression. However, the association of TIICs with prognosis in colorectal cancer (CRC) patients remains elusive. Infiltration of TIICs was assessed using ssGSEA and CIBERSORT tools. The association of TIICs with prognosis was analyzed in 1,802 CRC data downloaded from the GEO (https://www.ncbi.nlm.nih.gov/geo/) and TCGA (https://portal.gdc.cancer.gov/) databases. Three populations of TIICs, including CD66b+ tumor-associated neutrophils (TANs), FoxP3+ Tregs, and CD163+ tumor-associated macrophages (TAMs) were selected for immunohistochemistry (IHC) validation analysis in 1,008 CRC biopsies, and their influence on clinical features and prognosis of CRC patients was analyzed. Prognostic models were constructed based on the training cohort (359 patients). The models were further tested and verified in testing (249 patients) and validation cohorts (400 patients). Based on ssGSEA and CIBERSORT analysis, the correlation between TIICs and CRC prognosis was inconsistent in different datasets. Moreover, the results with disease-free survival (DFS) and overall survival (OS) data in the same dataset also differed. The high abundance of TIICs found by ssGSEA or CIBERSORT tools can be used for prognostic evaluation effectively. IHC results showed that TANs, Tregs, TAMs were significantly correlated with prognosis in CRC patients and were independent prognostic factors (P_DFS ≤ 0.001; P_OS ≤ 0.023). The prognostic predictive models were constructed based on the numbers of TANs, Tregs, TAMs (C-index_DFS&OS = 0.86; AIC_DFS = 448.43; AIC_OS = 184.30) and they were more reliable than traditional indicators for evaluating prognosis in CRC patients. Besides, TIICs may affect the response to chemotherapy. In conclusion, TIICs were correlated with clinical features and prognosis in patients with CRC and thus can be used as markers.

The Tumor Microenvironment in Colorectal Cancer Therapy

The current standard-of-care for metastatic colorectal cancer (mCRC) includes chemotherapy and anti-angiogenic or anti-epidermal growth factor receptor (EGFR) monoclonal antibodies, even though the addition of anti-angiogenic agents to backbone chemotherapy provides little benefit for overall survival. Since the approval of anti-angiogenic monoclonal antibodies bevacizumab and aflibercept, for the management of mCRC over a decade ago, extensive efforts have been devoted to discovering predictive factors of the anti-angiogenic response, unsuccessfully. Recent evidence has suggested a potential correlation between angiogenesis and immune phenotypes associated with colorectal cancer. Here, we review evidence of interactions between tumor angiogenesis, the immune microenvironment, and metabolic reprogramming. More specifically, we will highlight such interactions as inferred from our novel immune-metabolic (IM) signature, which groups mCRC into three distinct clusters, namely inflamed-stromal-dependent (IM Cluster 1), inflamed-non stromal-dependent (IM Cluster 2), and non-inflamed or cold (IM Cluster 3), and discuss the merits of the IM classification as a guide to new immune-metabolic combinatorial therapeutic strategies in mCRC.

Overexpression of PDE4A Acts as Checkpoint Inhibitor Against cAMP-Mediated Immunosuppression in vitro

Malignant cells acquire physiological mechanisms of immunosuppression to escape immune surveillance. Strategies to counteract this suppression could help to improve adoptive immunotherapy regimen. The intracellular second messenger cyclic AMP (cAMP) acts as a potent immunosuppressive signaling molecule in T-cells and is up-regulated by multiple tumor-relevant suppressive factors including prostaglandin E2 (PGE2), adenosine and the functions of regulatory T-cells. Consequently, we aimed to abrogate cAMP signaling in human T-cells by ectopic overexpression of phosphodiesterase 4A (PDE4A). We could show that retroviral transduction of PDE4A into T-cells led to efficient degradation of cAMP in response to induction of adenylate cyclase. Retroviral transduction of PDE4A into CD4⁺ and CD8⁺ T-cells restored proliferation, cytokine secretion as well as cytotoxicity under immunosuppression by PGE2 and A2A-R agonists. PDE4A-transgenic T-cells were also partially protected from suppression by regulatory T-cells. Furthermore, PGE2-mediated upregulation of the inhibitory surface markers CD73 and CD94 on CD8⁺ T-cells was efficiently counteracted by PDE4A. Importantly, no differences in the functionality under non-suppressive conditions between PDE4A- and control-vector transduced T-cells were observed, indicating that PDE4A does not interfere with T-cell activation per se. Similarly, expression of surface markers associated with T-cell exhaustion were not influenced by PDE4A overexpression in long term cultures. Thus, we provide first in vitro evidence that PDE4A can be exploited as immune checkpoint inhibitor against multiple suppressive factors.

Regulation of regulatory T cells in cancer

The inflammatory response to transformed cells forms the cornerstone of natural or therapeutically induced protective immunity to cancer. Regulatory T (Treg) cells are known for their critical role in suppressing inflammation, and therefore can antagonize effective anti-cancer immune responses. As such, Treg cells can play detrimental roles in tumour progression and in the response to both conventional and immune-based cancer therapies. Recent advances in our understanding of Treg cells reveal complex niche-specific regulatory programmes and functions, which are likely to extrapolate to cancer. The regulation of Treg cells is reliant on upstream cues from haematopoietic and non-immune cells, which dictates their genetic, epigenetic and downstream functional programmes. In this review we will discuss how Treg cells are themselves regulated in normal and transformed tissues, and the implications of this cross talk on tumour growth.

Expression of costimulatory and inhibitory receptors in FoxP3+ regulatory T cells within the tumor microenvironment: Implications for combination immunotherapy approaches

The unprecedented success of immune checkpoint inhibitors has given rise to a rapidly growing number of immuno-oncology agents undergoing preclinical and clinical development and an exponential increase in possible combinations. Defining a clear rationale for combinations by identifying synergies between immunomodulatory pathways has therefore become a high priority. Immunosuppressive regulatory T cells (Tregs) within the tumor microenvironment (TME) represent a major roadblock to endogenous and therapeutic tumor immunity. However, Tregs are also essential for the maintenance of immunological self-tolerance, and share many molecular pathways with conventional T cells including cytotoxic T cells, the primary mediators of tumor immunity. Hence the inability to specifically target and neutralize Tregs within the TME of cancer patients without globally compromising self-tolerance poses a significant challenge. Here we review recent advances in the characterization of tumor-infiltrating Tregs with a focus on costimulatory and inhibitory receptors. We discuss receptor expression patterns, their functional role in Treg biology and mechanistic insights gained from targeting these receptors in preclinical models to evaluate their potential as clinical targets. We further outline a framework of parameters that could be used to refine the assessment of Tregs in cancer patients and increase their value as predictive biomarkers. Finally, we propose modalities to integrate our increasing knowledge on Treg phenotype and function for the rational design of checkpoint inhibitor-based combination therapies. Such combinations have great potential for synergy, as they could concomitantly enhance cytotoxic T cells and inhibit Tregs within the TME, thereby increasing the efficacy of current cancer immunotherapies.

Colorectal cancer, radiotherapy and gut microbiota

Colorectal cancer is closely related to inflammation and immune response. Radiotherapy, as a major treatment for colorectal cancer, plays a central role in cancer control. Inflammation caused by ionizing radiation can exert either anti- or pro-tumorigenic effects. Additionally, radiotherapy can elicit an anti-tumor response not only in radiation of target lesions but also in radiation of remote lesions. However, the immune mechanism underlying this effect has not been thoroughly elucidated yet. The combination therapeutic regimen of radiotherapy with other therapeutic methods, including chemotherapy and immunotherapy, has been applied in clinical practice. Meanwhile, radiation toxicity and radiosensitivity have long been problems that affect a patient's quality of life and morbidity. Researchers have found that the abovementioned problems are closely associated with gut microbiota. Here we discuss the impact of immune response induced by radiotherapy on tumor regression and the impact of intestinal flora on the consequent clinical efficacy.