Regulatory T cells in gastrointestinal tumors

Investigation on the regulatory T cells signature and relevant Foxp3/STAT3 axis in esophageal cancer

BACKGROUND

Regulatory T cells (Tregs) have an important role in accelerating the immunosuppression of tumor. Tregs regulation is a hopeful strategy to improve the dismal prognosis of Esophageal cancer (EC), while its mechanisms have not yet been fully clarified.

METHODS

To characterize the role of Tregs in EC, we comprehensively explored its prognostic value, clinical pathology partnership, related biological functions and potential mechanisms at transcriptome level. Through the integrated analysis of GEO and TCGA datasets, we comprehensively evaluated the Tregs infiltration patterns in EC patients. The correlation between Tregs infiltration and genomic characteristics, as well as biological functions were analyzed by a variety of computational algorithms.

RESULTS

We observed that Tregs were significantly upregulated in EC and involved in various immune processes. According to TCGA and GEO transcriptional classification schemes, Tregs specific genes were observed to be highly expressed in tumor samples, as well as were closely associated with poor prognosis and worse clinical outcomes. In addition, EC patients can be stratified into high-risk and low-risk immune subgroups according to Tregs/macrophages infiltration level, and the results showed significant differences in tumor development, biological processes and probe gene expression pattern. The multi-variate analysis revealed that the interaction between STAT3 and Foxp3 was a potential prognostic signature of Tregs in EC, especially the modulation effect of STAT3 on Foxp3 expression, which has not been well studied in EC. We also identified that STAT3 and Foxp3 expression presented a high accuracy in predicting Tregs infiltration level in EC patients (AUC: 0.817; 95% CI: 0.756-0.878).

CONCLUSIONS

Our results revealed that Tregs have the potential to predict prognosis and tumor deterioration in EC patients. A comprehensive landscape of Tregs regulation mechanisms will help us interpret the immunosuppression of tumor microenvironment (TME) and novel strategies for EC immunotherapy.

Biophysics involved in the process of tumor immune escape

Much of the current research into immune escape from cancer is focused on molecular and cellular biology, an area of biophysics that is easily overlooked. A large number of immune drugs entering the clinic are not effective for all patients. Apart from the molecular heterogeneity of tumors, the biggest reason for this may be that knowledge of biophysics has not been considered, and therefore an exploration of biophysics may help to address this challenge. To help researchers better investigate the relationship between tumor immune escape and biophysics, this paper provides a brief overview on recent advances and challenges of the biophysical factors and strategies by which tumors acquire immune escape and a comprehensive analysis of the relevant forces acting on tumor cells during immune escape. These include tumor and stromal stiffness, fluid interstitial pressure, shear stress, and viscoelasticity. In addition, advances in biophysics cannot be made without the development of detection tools, and this paper also provides a comprehensive summary of the important detection tools available at this stage in the field of biophysics.

Impacts of Cigarette Smoking on the Tumor Immune Microenvironment in Esophageal Squamous Cell Carcinoma

Objective: Cigarette smoking is a carcinogenic factor for esophageal cancer and evidence also indicates its effects on tumor microenvironment in patients with esophageal squamous cell carcinoma (ESCC). Materials and Methods: In our study, we demonstrated nine immune infiltrating cells and markers in non-smokers and smokers of 189 non-drinking ESCC patients with multiplex fluorescent immunohistochemistry (mflHC) staining and multispectral imaging. The impacts of cigarette smoking on tumor microenvironment and patient prognosis were also analyzed. Results: Among 189 ESCC patients of non-drinker, 86 patients was current smokers, while 34 males and 59 females were non-smokers and 10 former-smokers. Among 34 male non-smokers and 83 smokers, distinct immune infiltrating cells, with increased DCs in stromal regions (P=0.033), elevated infiltration of Treg cells in intraepithelial regions (P=0.010) and reduced activate cytotoxic T lymphocytes (aCTLs) in both intraepithelial (P=0.021) and stromal regions (P=0.017), were observed in tumor specimens of smoking males, implying an immune suppressed response during cigarette smoke exposure. For smoking characters, the level of stromal tumor-associated macrophages (TAMs) infiltration was correlated with smoking year after age adjusted (r_s =0.352, P=0.002). Though cigarette smoking did not alter the expression of programmed death ligand 1 (PD-L1) in epithelial cells or TAMs in tumor specimens, higher expression of PD-L1 predicted a worse survival in non-smokers but not smokers. Conclusions: Our findings indicated smoking may impair T cell-mediated immune response and supported the possible impacts of cigarette smoking in PD-L1 related research and therapy of ESCC.

The role of myeloid-derived suppressor cells in gastrointestinal cancer

Gastrointestinal (GI) cancer encompasses a range of malignancies that originate in the digestive system, which together represent the most common form of cancer diagnosed worldwide. However, despite numerous advances in both diagnostics and treatment, the incidence and mortality rate of GI cancer are on the rise. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that increase in number under certain pathological conditions, such as infection and inflammation, and this expansion is of particular relevance to cancer. MDSCs are heavily involved in the regulation of the immune system and act to dampen its response to tumors, favoring the escape of tumor cells from immunosurveillance and increasing both metastasis and recurrence. Several recent studies have supported the use of MDSCs as a prognostic and predictive biomarker in patients with cancer, and potentially as a novel treatment target. In the present review, the mechanisms underlying the immunosuppressive functions of MDSCs are described, and recent researches concerning the involvement of MDSCs in the progression, prognosis, and therapies of GI cancer are reviewed. The aim of this work was to present the development of novel treatments targeting MDSCs in GI cancer in the hope of improving outcomes for patients with this condition.

Single-Cell Deconvolution of Head and Neck Squamous Cell Carcinoma

Complexities in cell-type composition have rightfully led to skepticism and caution in the interpretation of bulk transcriptomic analyses. Recent studies have shown that deconvolution algorithms can be utilized to computationally estimate cell-type proportions from the gene expression data of bulk blood samples, but their performance when applied to tumor tissues, including those from head and neck, remains poorly characterized. Here, we use single-cell data (~6000 single cells) collected from 21 head and neck squamous cell carcinoma (HNSCC) samples to generate cell-type-specific gene expression signatures. We leverage bulk RNA-seq data from >500 HNSCC samples profiled by The Cancer Genome Atlas (TCGA), and using single-cell data as a reference, apply two newly developed deconvolution algorithms (CIBERSORTx and MuSiC) to the bulk transcriptome data to quantitatively estimate cell-type proportions for each tumor in TCGA. We show that these two algorithms produce similar estimates of constituent/major cell-type proportions and that a high T-cell fraction correlates with improved survival. By further characterizing T-cell subpopulations, we identify that regulatory T-cells (Tregs) were the major contributor to this improved survival. Lastly, we assessed gene expression, specifically in the Treg population, and found that TNFRSF4 (Tumor Necrosis Factor Receptor Superfamily Member 4) was differentially expressed in the core Treg subpopulation. Moreover, higher TNFRSF4 expression was associated with greater survival, suggesting that TNFRSF4 could play a key role in mechanisms underlying the contribution of Treg in HNSCC outcomes.

Intestinal Bacteria Encapsulated by Biomaterials Enhance Immunotherapy

The human intestine contains thousands of bacterial species essential for optimal health. Aside from their pathogenic effects, these bacteria have been associated with the efficacy of various treatments of diseases. Due to their impact on many human diseases, intestinal bacteria are receiving increasing research attention, and recent studies on intestinal bacteria and their effects on treatments has yielded valuable results. Particularly, intestinal bacteria can affect responses to numerous forms of immunotherapy, especially cancer therapy. With the development of precision medicine, understanding the factors that influence intestinal bacteria and how they can be regulated to enhance immunotherapy effects will improve the application prospects of intestinal bacteria therapy. Further, biomaterials employed for the convenient and efficient delivery of intestinal bacteria to the body have also become a research hotspot. In this review, we discuss the recent findings on the regulatory role of intestinal bacteria in immunotherapy, focusing on immune cells they regulate. We also summarize biomaterials used for their delivery.

Analysis of the efficacy, safety and survival factors of stereotactic body radiation therapy in patients with recurrence of pancreatic cancer

Objective: This study aims to evaluate the efficacy and safety of stereotactic body radiation therapy (SBRT) using Cyber Knife (CK) in the treatment of patients with recurrent pancreatic cancer after surgery, and analyze its survival-related factors. Methods: The primary endpoint was freedom from local progression (FFLP) and local control (LC) rate after CK. The secondary endpoints were overall survival (OS), progression-free survival (PFS), symptom relief and toxicities. Receiver operating characteristic (ROC) curves were used to determine the optimal cut-off values of inflammatory composite indicators NLR, PLR, SII and PNI. The prognostic factors that affected these patients were analyzed by univariate and multivariate analysis, respectively. Results: A total of 27 patients were enrolled. Median local recurrence disease free interval（DFI）was 11.3 (1.3-30.6) months, LC was 81.5% and 37.0% at 6 and 12 months, respectively. Median PFS was 7.1 (1.3-27.1) months. Median OS was 11.3 (1.3-30.6) months. Symptom alleviation was observed in 16 of 17 patients (94.1%) within 2 weeks after CK. Subsequent chemotherapy, CA199≥50% decrease after CK were independent prognostic factors for OS (all P <0.05). Conclusion: SBRT is a safe and effective treatment approach for recurrent pancreatic adenocarcinoma. Encouraging local control rate, low toxicity, and effective symptom relief suggests the vital role of CK in the treatment of these patients. This clinical application needs to be further studied in the combination of CK and multimodal therapy.

Relationship between intestinal microorganisms and T lymphocytes in colorectal cancer

Colorectal cancer (CRC) is a common type of malignant cancer worldwide. Recent studies have identified the gut microbiota as the origin of CRC, and T lymphocyte-mediated immune functions have been shown to play an important role in this disease. By summarizing previous literature, we found that Fusobacterium nucleatum may protect CRC from immune cell attack by inhibiting T cells and influencing the production of many chemokines and cytokines. Some bacterial metabolites and probiotics have been shown to participate in the regulation of CRC through T cell-mediated molecular pathways. To visualize the relevant data, an association network of intestinal microorganisms and T lymphocytes associated with CRC was constructed. This work may provide direction for - and insight into - further research on the relationship between intestinal microorganisms and T lymphocytes in CRC.

Expression of Th17/Treg related molecules in gastric cancer tissues

BACKGROUND/AIMS

The function of regulatory T cells (Treg) and helper T cells 17 (Th17) related indexes, such as interleukin (IL)-6, IL-17, transforming growth factor (TGF)-β1, and forkhead box protein 3(FoxP3) in gastric adenocarcinoma tissues remains undefined. We investigated and analyzed the relevance of the proteins with the clinicopathological characteristics and the interactions among them in gastric cancer.

MATERIALS AND METHODS

A total 68 gastric cancer patients and 40 healthy controls were enrolled. Immunohistochemistry (IHC) as well as quantitative real-time reverse transcription- polymerase chain reaction (RT-PCR) was used to determine the expression levels of IL-6, TGF-β1, IL-17, and FoxP3 in the prepared tissues. Statistical analysis included ANOVA and chi-square test.

RESULTS

The expression levels of IL-6, IL-17, FoxP3, and TGF-β1 had significantly increased in cancer tissues compared to controls. Clinical staging of gastric cancer were correlated with the rise of IL-6, IL-17, FoxP3, and TGF-β1 levels expressed in cancer tissues. The expression level of TGF-β1 and IL-6 was positively related to that of IL-17 and FoxP3, similar to FoxP3 and IL-17 in gastric cancer tissues.

CONCLUSION

IL-6, TGF-β1, FoxP3, and IL-17 may promote the progression of gastric cancer individually or jointly and have complex interactions.

Regulatory T cells in malignant pleural effusions subsequent to lung carcinoma and their impact on the course of the disease

Tumors exert suppressive effects on the host immune system and tumor progression can be linked to functional impairments of immune cells. Regulatory T cells (Treg) are a subpopulation of T lymphocytes and play a key role in suppressing immune responses against autoimmune diseases and cancer. The aim of the study was to investigate the prevalence of Treg in malignant and benign pleural effusions and to evaluate the relationship between Treg frequency and disease advance. Pleural effusions from 76 patients were subjected to a routine laboratory diagnosis and analyzed by conventional cytology. Biological materials were divided into three groups: malignant pleural effusions with malignant cells, effusions from patients with malignancy but without malignant cells, and non-malignant pleural effusions. The frequency of Treg in malignant pleural effusions was significantly higher compared to non-malignant effusions. In general, the increase in Treg frequency was correlated with a decrease in the percentage of lymphocytes and an increase in T CD4+ and T CD4+ CD25+ cells. The highest percentage of Treg was observed among patients with the most advanced clinical stage of lung cancer in terms of size and location of a primary tumor, T4. A Kaplan-Meier survival analysis showed a statistically significant trend towards an adverse outcome for patients representing higher Treg counts. Overall, our results support the extraordinary potential of Treg control in future anticancer therapy.

Regulatory T Cells from Colon Cancer Patients Inhibit Effector T-cell Migration through an Adenosine-Dependent Mechanism

T cell-mediated immunity is a major component of antitumor immunity. In order to be efficient, effector T cells must leave the circulation and enter into the tumor tissue. Regulatory T cells (Treg) from gastric cancer patients, but not from healthy volunteers, potently inhibit migration of conventional T cells through activated endothelium. In this study, we compared T cells from colon cancer patients and healthy donors to determine the mechanisms used by Tregs from cancer patients to inhibit conventional T-cell migration. Our results showed that circulating Tregs from cancer patients expressed high levels of CD39, an ectoenzyme mediating hydrolysis of ATP to AMP, as a rate-determining first step in the generation of immunosuppressive adenosine. Tumor-associated Tregs expressed even more CD39, and we therefore examined the importance of adenosine in Treg-mediated inhibition of T-cell transendothelial migration in vitro. Exogenous adenosine significantly reduced migration of conventional T cells from healthy volunteers, and blocking either adenosine receptors or CD39 enzymatic activity during transmigration restored the ability of conventional T cells from cancer patients to migrate. Adenosine did not directly affect T cells or endothelial cells, but reduced the ability of monocytes to activate the endothelium. Taken together, our results indicate that Treg-derived adenosine acts on monocytes and contributes to reduced transendothelial migration of effector T cells into tumors. This effect of Tregs is specific for cancer patients, and our results indicate that Tregs may affect not only T-cell effector functions but also their migration into tumors.

Innovative perspectives of immunotherapy in head and neck cancer. From relevant scientific rationale to effective clinical practice

It is now well established that head and neck cancer carcinogenesis is characterized by genetic instability and several immune defects, leading to unique host-tumor interactions. In such condition, recent improved comprehension and relevant findings could lead to identification of innovative molecular therapeutic targets, achieving considerable clinical and translational research. This review aims to summarize and to highlight most recent and relevant scientific rationale in this era of immunotherapy revival, and to correlate it to the near future clinical practice for the management of this challenging disease.

Treg-cell depletion promotes chemokine production and accumulation of CXCR3(+) conventional T cells in intestinal tumors

Colorectal cancer (CRC) is one of the most prevalent tumor types worldwide and tumor-infiltrating T cells are crucial for anti-tumor immunity. We previously demonstrated that Treg cells from CRC patients inhibit transendothelial migration of conventional T cells. However, it remains unclear if local Treg cells affect lymphocyte migration into colonic tumors. By breeding APC(Min/+) mice with depletion of regulatory T cells mice, expressing the diphtheria toxin receptor under the control of the FoxP3 promoter, we were able to selectively deplete Treg cells in tumor-bearing mice, and investigate the impact of these cells on the infiltration of conventional T cells into intestinal tumors. Short-term Treg-cell depletion led to a substantial increase in the frequencies of T cells in the tumors, attributed by both increased infiltration and proliferation of T cells in the Treg-cell-depleted tumors. We also demonstrate a selective increase of the chemokines CXCL9 and CXCL10 in Treg-cell-depleted tumors, which were accompanied by accumulation of CXCR3(+) T cells, and increased IFN-γ mRNA expression. In conclusion, Treg-cell depletion increases the accumulation of conventional T cells in intestinal tumors, and targeting Treg cells could be a possible anti-tumor immunotherapy, which not only affects T-cell effector functions, but also their recruitment to tumors.

Altered chemokine production and accumulation of regulatory T cells in intestinal adenomas of APC(Min/+) mice

Tumor progression in the colon moves from aberrant crypt foci to adenomatous polyps to invasive carcinomas. The composition of the tumor-infiltrating leukocyte population affects the ability of the immune system to fight the tumor. T cell infiltration into colorectal adenocarcinomas, particularly T helper 1 (Th1) type T cells as well as increased regulatory T cell (Treg) frequencies, is correlated with improved prognosis. However, whether Th1 cells and Tregs are already present at the adenoma stage is not known. In this study, the APC(Min/+) mouse model of intestinal adenomatous polyposis was used to investigate tumor-associated lymphocyte subsets and the mechanisms of their accumulation into gastrointestinal adenomas. Compared to unaffected tissue, adenomas accumulated CD4(+)FoxP3(+) putative Treg in parallel with lower frequencies of conventional T cells and B cells. The accumulation of Treg was also observed in human adenomatous polyps. Despite high Treg numbers, the function of conventional T cells present in the APC(Min/+) adenomas was not different from those in the unaffected tissue. Adenomas displayed an altered chemokine balance, with higher CCL17 and lower CXCL11 and CCL25 expression than in the unaffected tissue. In parallel, CXCR3(+) Tregs were largely absent from adenomas. The data indicate that already in early stages of tumor development, the balance of lymphocyte-recruiting chemokines is altered possibly contributing to the observed shift toward higher frequencies of Treg.

The effect of immune microenvironment on the progression and prognosis of colorectal cancer

Cancer cells may escape from host immune responses through active suppression of the immune response, but the detailed mechanisms in colorectal cancer remain to be elucidated. In this study, 108 colorectal tumor samples and their peritumoral tissues were collected for immunohistochemistry of infiltrating lymphocytes. Th1 and Tregs cells were determined by the positive expression of T-bet and FOXP3 proteins, respectively. The Tr1 cells were identified by CD49b and LAG-3 protein expression. IL-17-positive cells were identified by IL-17 expression. Results showed that the percentage of T-bet-positive cells was significantly decreased, while the percentages of IL-17-, FOXP3-, CD49b-, and LAG-3-positive cells were significantly increased in tumor tissues compared to that in peritumoral tissues. The ratio of IL-17-, FOXP3-, CD49b-, and LAG3-positive cells to T-bet-positive cells was significantly higher in tumor tissues than in peritumoral tissues. The percentage of infiltrating IL-17-positive cells in tumor tissues was negatively associated with lymph metastasis, invasion, and TNM stage. The percentage of CD49b- and LAG-3-positive cells was positively associated with differentiation, lymph metastasis, invasion, TNM, and Duke stage of colorectal cancer. The percentage of positive Th17 and Tr1 cells is a marker for poor prognosis in patients with CRC. In conclusion, decreased composition of regulative Th1 cells and increased composition of FOXP(+) Tregs-, CD49b(+)/LAG-3(+) Tr1-, and IL-17-positive cells in tumor tissues may be associated with the progression of colorectal cancer. The high percentage of IL-17- and Tr1-positive cells in tumor tissues is a predictive marker for poor prognosis of colorectal cancer.

High level of Tregs is a positive prognostic marker in patients with HPV-positive oral and oropharyngeal squamous cell carcinomas

BACKGROUND

Human papillomaviruses (HPVs) have been proved as one of the etiological factors of oropharyngeal squamous cell carcinoma (OPSCC). Patients with tumors of viral etiology have a lower recurrence rate and better prognosis. OPSCC is linked to an alteration in the immune system. Only a limited number of studies have correlated both the immunological parameters and HPV status with patient prognosis. The aim of this study was to determine whether HPV infection and the immunological status influence patient prognosis individually or in concurrence.

MATERIAL AND METHODS

Sixty patients with oral and oropharyngeal carcinomas were enrolled. They were divided into HPV-positive and HPV-negative groups based on the expression of HPV 16 E6 mRNA. Basic lymphocyte subpopulations were determined in the peripheral blood by means of flow cytometry.

RESULTS

Significantly better disease-specific survival (DSS) was observed in patients with HPV-positive tumors. Nodal status, tumor grade, recurrence, and CD8+/Tregs ratio were identified as factors influencing DSS. A higher level of Tregs and a lower ratio of CD8/Tregs influenced overall survival (OS) independently of HPV status and age. Patients with HPV-positive tumors and high levels of Tregs survived significantly better than patients from the other groups.

CONCLUSION

Better survival is associated with HPV positivity and elevated Tregs levels. Our data suggest that HPV infection and Tregs do not influence patient prognosis in concurrence.

Intratumor hypoxia promotes immune tolerance by inducing regulatory T cells via TGF-β1 in gastric cancer

Regulatory T cell (Treg)-mediated immunosuppression represents one of the crucial tumor immune evasion mechanisms and is a main obstacle for successful tumor immunotherapy. Hypoxia, a common feature of solid tumors, has been associated with potentiated immunosuppression, decreased therapeutic response, malignant progression and local invasion. Unfortunately, the link between hypoxia and Treg-mediated immune tolerance in gastric cancer remains poorly understood. In our study, Tregs and hypoxia inducible factor-1α were found to be positively correlated with each other and were increased with the tumor progression. A subsequent in vitro study indicated that supernatants derived from gastric cancer cells under hypoxic condition, could induce the expression of Foxp3 via TGF-β1. These findings confirmed the crucial role of Tregs as a therapeutic target in gastric cancer therapy and provided helpful thoughts for the design of immunotherapy for gastric cancer in the future.

CD39 is highly involved in mediating the suppression activity of tumor-infiltrating CD8+ T regulatory lymphocytes

CD39 is an ectoenzyme, present on different immune cell subsets, which mediates immunosuppressive functions catalyzing ATP degradation. It is not known whether CD39 is expressed and implicated in the activity of CD8+ regulatory T lymphocytes (Treg). In this study, CD39 expression and function was analyzed in both CD8+ and CD4+CD25(hi) Treg from the peripheral blood of healthy donors as well as from tumor specimens. CD39 was found expressed by both CD8+ (from the majority of healthy donors and tumor patients) and CD4+CD25(hi) Treg, and CD39 expression correlated with suppression activity mediated by CD8+ Treg. Importantly, CD39 counteraction remarkably inhibited the suppression activity of CD8+ Treg (both from peripheral blood and tumor microenvironment) suggesting that CD39-mediated inhibition constitutes a prevalent hallmark of their function. Collectively, these findings, unveiling a new mechanism of action for CD8+ Treg, provide new knowledge on intratumoral molecular pathways related to tumor immune escape, which could be exploited in the future for designing new biological tools for anticancer immune intervention.

Absence of CD4 T-cell help provides a robust CD8 T-cell response while inducing effective memory in a preclinical model of melanoma

Immunotherapy strategies for cancer are focused on inducing effective and specific cytotoxic responses mediated by CD8 T cells. On the other hand, immunosuppressive mechanisms induced by the tumor, such as the generation of tumor-specific CD4(+)CD25(+)FoxP3(+) Tregs, conspire against the efficacy of immunotherapies. It has been considered that, similar to what has been observed in the context of immunological responses towards microbes, CD4 help is indispensable for the development of a successful and long-lasting (memory) CD8 immune response. In the recent article, Côté et al. reported that, in a mouse model of melanoma, total ablation of CD4 help does not hamper the development of a specific antitumor memory CD8 response. In addition, ablation of CD4 was more successful than strategies to deplete CD25 Tregs in generating memory CD8 T cells. These data opens the door for therapies destined to induce effective antitumor immune responses by ablation of whole CD4 T-cell populations.