Expansion of human T regulatory type 1 cells in the microenvironment of cyclooxygenase 2 overexpressing head and neck squamous cell carcinoma

Evolving Tumor Characteristics and Smart Nanodrugs for Tumor Immunotherapy

Typical physiological characteristics of tumors, such as weak acidity, low oxygen content, and upregulation of certain enzymes in the tumor microenvironment (TME), provide survival advantages when exposed to targeted attacks by drugs and responsive nanomedicines. Consequently, cancer treatment has significantly progressed in recent years. However, the evolution and adaptation of tumor characteristics still pose many challenges for current treatment methods. Therefore, efficient and precise cancer treatments require an understanding of the heterogeneity degree of various factors in cancer cells during tumor evolution to exploit the typical TME characteristics and manage the mutation process. The highly heterogeneous tumor and infiltrating stromal cells, immune cells, and extracellular components collectively form a unique TME, which plays a crucial role in tumor malignancy, including proliferation, invasion, metastasis, and immune escape. Therefore, the development of new treatment methods that can adapt to the evolutionary characteristics of tumors has become an intense focus in current cancer treatment research. This paper explores the latest understanding of cancer evolution, focusing on how tumors use new antigens to shape their "new faces"; how immune system cells, such as cytotoxic T cells, regulatory T cells, macrophages, and natural killer cells, help tumors become "invisible", that is, immune escape; whether the diverse cancer-associated fibroblasts provide support and coordination for tumors; and whether it is possible to attack tumors in reverse. This paper discusses the limitations of targeted therapy driven by tumor evolution factors and explores future strategies and the potential of intelligent nanomedicines, including the systematic coordination of tumor evolution factors and adaptive methods, to meet this therapeutic challenge.

Human mesenchymal stem cells increase LLC metastasis and stimulate or decelerate tumor development depending on injection method and cell amount

Mesenchymal stem cells (MSCs) being injected into the body can stimulate or decelerate carcinogenesis. Here, the direction of influence of human placenta-derived MSCs (P-MSCs) on the Lewis lung carcinoma (LLC) tumor development and metastatic potential is investigated in C57BL/6 mice depending on the injection method. After intramuscular co-inoculation of LLC and P-MSCs (LLC + P-MSCs), the growth of primary tumor and angiogenesis are slowed down compared to the control LLC on the 15th day. This is explained by the fact of a decrease in the secretion of proangiogenic factors during in vitro co-cultivation of an equal amount of LLC and P-MSCs. When P-MSCs are intravenously (i.v.) injected in the mice with developing LLC (LLC + P-MSCs(i.v.)), the tumor growth and angiogenesis are stimulated on the 15th day. A highly activated secretion of proangiogenic factors by P-MSCs in a similar in vitro model can explain this. In both the models compared to the control on the 23rd day, there is no significant difference in the tumor growth, while angiogenesis remains correspondingly decelerated or stimulated. However, in both the models, the total volume and number of lung metastases constantly increase compared to the control: it is mainly due to small-size metastases for LLC + P-MSCs(i.v.) and larger ones for LLC + P-MSCs. The increase in the rate of LLC cell dissemination after the injection of P-MSCs is explained by the disordered polyploidy and chromosomal instability, leading to an increase in migration and invasion of cancer cells. After LLC + P-MSCs co-inoculation, the tumor cell karyotype has the most complex and heterogeneous chromosomal structure. These findings indicate a bidirectional effect of P-MSCs on the growth of LLC in the early periods after injection, depending on the injection method, and, correspondingly, the number of contacting cells. However, regardless of the injection method, P-MSCs are shown to increase LLC aggressiveness related to cancer-associated angiogenesis and metastasis activation in the long term.

PGE2-EP4 signaling steers cDC2 maturation toward the induction of suppressive T-cell responses

Dendritic cells (DCs) shape adaptive immunity in response to environmental cues such as cytokines or lipid mediators, including prostaglandin E2 (PGE2). In cancer, tumors are known to establish an enriched PGE2 microenvironment. Tumor-derived PGE2 primes regulatory features across immune cells, including DCs, facilitating tumor progression. PGE2 shapes DC function by providing signaling via its two so-called E-prostanoid receptors (EPs) EP2 and EP4. Although studies with monocyte-derived DCs have shown the importance of PGE2 signaling, the role of PGE2-EP2/EP4 on conventional DCs type 2 (cDC2s), is still poorly defined. In this study, we investigated the function of EP2 and EP4 using specific EP antagonists on human cDC2s. Our results show that EP2 and EP4 exhibit different functions in cDC2s, with EP4 modulating the upregulation of activation markers (CD80, CD86, CD83, MHC class II) and the production of IL-10 and IL-23. Furthermore, PGE2-EP4 boosts CCR type 7-based migration as well as a higher T-cell expansion capacity, characterized by the enrichment of suppressive rather than pro-inflammatory T-cell populations. Our findings are relevant to further understanding the role of EP receptors in cDC2s, underscoring the benefit of targeting the PGE2-EP2/4 axis for therapeutic purposes in diseases such as cancer.

The Molecular and Cellular Strategies of Glioblastoma and Non-Small-Cell Lung Cancer Cells Conferring Radioresistance

Ionizing radiation (IR) has been shown to play a crucial role in the treatment of glioblastoma (GBM; grade IV) and non-small-cell lung cancer (NSCLC). Nevertheless, recent studies have indicated that radiotherapy can offer only palliation owing to the radioresistance of GBM and NSCLC. Therefore, delineating the major radioresistance mechanisms may provide novel therapeutic approaches to sensitize these diseases to IR and improve patient outcomes. This review provides insights into the molecular and cellular mechanisms underlying GBM and NSCLC radioresistance, where it sheds light on the role played by cancer stem cells (CSCs), as well as discusses comprehensively how the cellular dormancy/non-proliferating state and polyploidy impact on their survival and relapse post-IR exposure.

Framework of Intrinsic Immune Landscape of Dormant Prostate Cancer

Androgen deprivation therapy (ADT) is the standard therapy for men with advanced prostate cancer (PCa). PCa often responds to ADT and enters a dormancy period, which can be recognized clinically as a minimal residual disease. However, the majority of these patients will eventually experience a relapse in the form of castration-resistant PCa with poor survival. Therefore, ADT-induced dormancy is a unique time window for treatment that can provide a cure. The study of this well-recognized phase of prostate cancer progression is largely hindered by the scarcity of appropriate clinical tissue and clinically relevant preclinical models. Here, we report the utility of unique and clinically relevant patient-derived xenograft models in the study of the intrinsic immune landscape of dormant PCa. Using data from RNA sequencing, we have reconstructed the immune evasion mechanisms that can be utilized by dormant PCa cells. Since dormant PCa cells need to evade the host immune surveillance for survival, our results provide a framework for further study and for devising immunomodulatory mechanisms that can eliminate dormant PCa cells.

Human cytomegalovirus-induced immune regulation is correlated with poor prognosis in patients with colorectal cancer

Evidence suggests that human cytomegalovirus (HCMV) infection may be implicated in the progression of colorectal cancer (CRC). However, the correlation between HCMV infection and survival outcomes in patients with CRC remains unclear. Here, we constructed a flow algorithm to identify HCMV sequences based on the RNA-seq data of patients with CRC derived from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). The patients' clinical information matrix was used to calculate the Euclidean distance to filter out suitable patients not infected with HCMV, combined with patients' survival outcomes, to reveal how HCMV infection is involved in CRC progression. HCMV infection is widespread in patients with CRC, and the prevalence of HCMV infection ranges from 10 to 36% in four independent CRC datasets, with infection being concentrated in carcinoma tissue rather than in normal tissue. In addition, HCMV-positive patients had a poor survival prognosis, with three HCMV genes, UL82, UL42, and UL117, associated with poor patient survival outcomes. Most importantly, we suppose that the regulation of immune function by HCMV may be key to the poor prognosis of patients with CRC. We found that HCMV infection was associated with poor prognosis in CRC patients and identified three prognosis-associated HCMV genes. The regulation of immune function caused by HCMV infection was the key factor, while HCMV-positive patients with CRC mostly presented with a state of immunosuppression. This may provide new ideas for the personalized treatment of patients with CRC, especially with respect to immunotherapy.

Control of Dendritic Cell Function Within the Tumour Microenvironment

The tumour microenvironment (TME) presents a major block to anti-tumour immune responses and to effective cancer immunotherapy. The inflammatory mediators such as cytokines, chemokines, growth factors and prostaglandins generated in the TME alter the phenotype and function of dendritic cells (DCs) that are critical for a successful adaptive immune response against the growing tumour. In this mini review we discuss how tumour cells and the surrounding stroma modulate DC maturation and trafficking to impact T cell function. Fibroblastic stroma and the associated extracellular matrix around tumours can also provide physical restrictions to infiltrating DCs and other leukocytes. We discuss interactions between the inflammatory TME and infiltrating immune cell function, exploring how the inflammatory TME affects generation of T cell-driven anti-tumour immunity. We discuss the open question of the relative importance of antigen-presentation site; locally within the TME versus tumour-draining lymph nodes. Addressing these questions will potentially increase immune surveillance and enhance anti-tumour immunity.

Hypoxia, Serum Starvation, and TNF-α Can Modify the Immunomodulation Potency of Human Adipose-Derived Stem Cells

INTRODUCTION

Adipose-derived stem cells (ADSCs) are mesenchymal stem cells (MSCs) that are found in adipose tissues, which are easily obtained from liposuction procedures using an enzyme mixture. The adhering cells are then selectively cultivated. ADSCs have great potential in regenerative medicine because they are plentiful, easily accessible, and less invasive. They also have an impressive proliferation ability and can be differentiated into mesenchymal lineages and trans-differentiating into many other cell types. In particular, they have extraordinary abilities in immunomodulation. This study aimed to investigate the effects of culture conditions (hypoxia, starvation, and TNF-α treatment) on the immunomodulation of human ADSCs.

METHODS

Human ADSCs were expanded in vitro in the standard condition before they were cultured in different stress conditions. ADSCs from passages fifth were confirmed as MSCs by some standard assays suggested by the International Society for Cell and Gene Therapy. These MSCs were used to culture in four different stress conditions: hypoxia, serum starvation, and TNF-α treatment in 48 h. After treatments, MSCs were used to evaluate their immunomodulation capacity using MSCs mixed lymphocyte reaction assay, and the concentrations of IDO, PGE2, IL-6, and IL-10 were secreted in the culture medium.

RESULTS

In different stress conditions, ADSCs exhibited different responses related to their immunomodulation. In serum starvation, ADSCs exerted a strong secretion of IDO and PGE2, whereas they showed strong IL-6 secretion in the TNF-α-supplemented medium. When exposed to lymphocytes, ADSCs caused an increase in the ratio of regulatory T cells (Tregs), and co-culture lymphocytes with ADSCs induced in hypoxic malnutrition conditions increased the IL-10 level the most. In addition, when exposed to dendritic cells (DCs), ADSCs inhibited the mature marker expressions of the DCs.

CONCLUSION

The current research showed that ADSCs change their immunomodulation properties to survive in in vitro culture environments. Treatment of ADSCs in the starvation medium for 48 h can increase the immunomodulation of ADSCs.

Effects of Tumor-Derived Exosome Programmed Death Ligand 1 on Tumor Immunity and Clinical Applications

Programmed death ligand 1 (PD-L1) is a typical immune surface protein that binds to programmed cell death 1 (PD-1) on T cells through its extracellular domain. Subsequently, T cell activity is inhibited, and tumor immune tolerance is enhanced. Anti-PD-1/PD-L1 immune checkpoint therapy blocks the combination of PD-1/PD-L1 and rejuvenates depleted T cells, thereby inhibiting tumor growth. Exosomes are biologically active lipid bilayer nanovesicles secreted by various cell types, which mediate signal communication between cells. Studies have shown that PD-L1 can not only be expressed on the surface of tumor cells, immune cells, and other cells in the tumor microenvironment, but also be released from tumor cells and exist in an extracellular form. In particular, exosome PD-L1 plays an unfavorable role in tumor immunosuppression. The immunomodulatory effect of exosome PD-L1 and its potential in fluid diagnosis have attracted our attention. This review aims to summarize the available evidence regarding the biological characteristics of exosome PD-L1 in tumor immunity, with a particular focus on the mechanisms in different cancers and clinical prospects. In addition, we also summarized the current possible and effective detection methods for exosome PD-L1 and proposed that exosome PD-L1 has the potential to become a target for overcoming anti-PD-1/PD-L1 antibody treatment resistance.

Breast Cancer Cell-Derived Adenosine Enhances Generation and Suppressor Function of Human Adaptive Regulatory T Cells

Introduction: Adaptive regulatory T cells (Tr1) are induced in the periphery by environmental stimuli. CD73 expression and adenosine (ADO) production by tumor cells may influence Tr1 generation and their immunosuppressive activity. Material and Methods: Tr1 were generated in co-cultures of CD4+CD25neg T cells, autologous immature dendritic cells (iDC), and irradiated ADO-producing CD73+ or non-producing CD73neg breast cancer (BrCa) cell lines (TU). The expression of ectonucleotidases and other surface markers on Tr1 was determined by flow cytometry. Tr1-mediated suppression of proliferation was evaluated in CFSE-based assays. Luciferase-based ATP detection assays and mass spectrometry were used to measure ATP hydrolysis and ADO levels. Cytokine levels were measured by ELISA or Luminex. CD73 expression on tumor cells or T cells in TU tissues was assessed by immunofluorescence. Results: CD73+ TU induced higher numbers of Tr1 cells (p < 0.01) than CD73neg TU. Tr1TU73+ hydrolyzed more exogenous ATP, produced more ADO, and mediated higher suppression than Tr1TU73neg (p < 0.05 for all). ARL67156, an ectonucleotidase inhibitor, and ZM241385, A2A receptor antagonist, reduced suppression of proliferation mediated by Tr1TU73+ cells (p < 0.01). Basal-like primary BrCa cells expressed higher levels of ectonucleotidases and induced more Tr1 than less aggressive primary luminal-like BrCa. Conclusion: BrCa producing ADO (CD73+ TU) favor the induction of Tr1, which expresses CD39 and CD73, hydrolyzes ATP to ADO, and effectively suppresses anti-tumor immunity.

Mitochondrial-encoded MOTS-c prevents pancreatic islet destruction in autoimmune diabetes

Mitochondria are principal metabolic organelles that are increasingly unveiled as immune regulators. However, it is currently not known whether mitochondrial-encoded peptides modulate T cells to induce changes in phenotype and function. In this study, we found that MOTS-c (mitochondrial open reading frame of the 12S rRNA type-c) prevented autoimmune β cell destruction by targeting T cells in non-obese diabetic (NOD) mice. MOTS-c ameliorated the development of hyperglycemia and reduced islet-infiltrating immune cells. Furthermore, adoptive transfer of T cells from MOTS-c-treated NOD mice significantly decreased the incidence of diabetes in NOD-severe combined immunodeficiency (SCID) mice. Metabolic and genomic analyses revealed that MOTS-c modulated T cell phenotype and function by regulating T cell receptor (TCR)/mTOR complex 1 (mTORC1) signaling. Type 1 diabetes (T1D) patients had a lower serum MOTS-c level than did healthy controls. Furthermore, MOTS-c reduced T cell activation by alleviating T cells from the glycolytic stress in T1D patients, suggesting therapeutic potential. Our findings indicate that MOTS-c regulates the T cell phenotype and suppresses autoimmune diabetes.

Immune Checkpoints Pathways in Head and Neck Squamous Cell Carcinoma

Simple Summary

During the last decades, scientific advances in immuno-oncology and a better understanding of tumors’ immune profile led to the development of novel immunotherapeutic strategies, especially immune checkpoint inhibitors. The blockade of PD-1 by monoclonal antibodies (mAbs) is the only immunotherapy based on immune checkpoint pathways approved for head and neck squamous cell carcinoma. As only a small fraction of patients perceives clinical benefit, understanding the molecular mechanisms and signaling pathways activated by the immune checkpoints and other tumor intrinsic features that modulate the immune infiltrate is crucial to better select patients for immunotherapy treatment and to develop novel therapeutic strategies. We here review the immune escape mechanisms of head and neck tumors, with a particular focus on the immune checkpoints, their role as therapeutic targets, and the predictive biomarkers of response to anti-PD-1/PD-L1 therapy. We also summarize the ongoing clinical trials testing several combinations of immune checkpoint inhibitors with other therapeutic approaches to improve patient outcomes.

Abstract

Head and neck squamous cell carcinoma (HNSCC) is a heterogeneous group of tumors usually diagnosed at an advanced stage and characterized by a poor prognosis. The main risk factors associated with its development include tobacco and alcohol consumption and Human Papillomavirus (HPV) infections. The immune system has a significant role in the oncogenesis and evolution of this cancer type. Notably, the immunosuppressive tumor microenvironment triggers immune escape through several mechanisms. The improved understanding of the antitumor immune response in solid tumors and the role of the immune checkpoint molecules and other immune regulators have led to the development of novel therapeutic strategies that revolutionized the clinical management of HNSCC. However, the limited overall response rate to immunotherapy urges identifying predictive biomarkers of response and resistance to treatment. Here, we review the role of the immune system and immune checkpoint pathways in HNSCC, the most relevant clinical findings linked to immunotherapeutic strategies and predictive biomarkers of response and future treatment perspectives.

Lipid Metabolism in Tumor-Infiltrating T Cells

T cells recognize "foreign" antigens and induce durable humoral and cellular immune responses, which are indispensable for defending pathogens, as well as maintaining the integrity and homeostasis of tissues and organs. T cells are the major immune cell population in the tumor microenvironment which play a critical role in the antitumor immune response and cancer immune surveillance. Defective immune response of tumor-infiltrating T cells is the main cause of cancer immune evasion. The antitumor response of T cells is affected by multiple factors in the tumor microenvironment, including immunosuppressive cells, immune inhibitory cytokines, tumor-derived suppressive signals like PD-L1, immnuogenicity of tumor cells, as well as metabolic factors like hypoxia and nutrient deprivation. Abundant studies in past decades have proved the metabolic regulations of the immune response of T cells and the tumor-infiltrating T cells. In this chapter, we will discuss the regulations of the antitumor response of tumor-infiltrating T cells by lipid metabolism, which is one of the main components of metabolic regulation.

Immune Modulation in Lung Cancer: Current Concepts and Future Strategies

Cancer immunotherapy represents the most dynamic field of biomedical research currently, with thoracic immuno-oncology as a forerunner. PD-(L)1 inhibitors are already part of standard first-line treatment for both non-small-cell and small-cell lung cancer, while unprecedented 5-year survival rates of 15-25% have been achieved in pretreated patients with metastatic disease. Evolving strategies are mainly aiming for improvement of T-cell function, increase of immune activation in the tumor microenvironment (TME), and supply of tumor-reactive lymphocytes. Several novel therapeutics have demonstrated preclinical efficacy and are increasingly used in rational combinations within clinical trials. Two overarching trends dominate: extension of immunotherapy to earlier disease stages, mainly as neoadjuvant treatment, and a shift of focus towards multivalent, individualized, mutatome-based antigen-specific modalities, mainly adoptive cell therapies and cancer vaccines. The former ensures ample availability of treated and untreated patient samples, the latter facilitates deeper mechanistic insights, and both in combination build an overwhelming force that is accelerating progress and driving the greatest revolution cancer medicine has seen so far. Today, immune modulation represents the most potent therapeutic modality in oncology, the most important topic in clinical and translational cancer research, and arguably our greatest, meanwhile justified hope for achieving cure of pulmonary neoplasms and other malignancies in the next future.

Immune Suppressive Effects of Plasma-Derived Exosome Populations in Head and Neck Cancer

Plasma-derived exosomes of head and neck squamous cell carcinoma (HNSCC) patients carry inhibitory factors mediating immune suppression. Separation of tumor-derived exosomes (TEX) and non-TEX may assist in a better understanding of their respective parental cells. Here, we evaluate the impact of TEX or hematopoietic-derived exosomes on immune suppression. We evaluated apoptosis in CD8+ T cells, conversion of CD4+ T cells to regulatory T cells (T_reg), and adenosine production by TEX, non-TEX, or total exosomes. Exosome protein cargo was significantly higher in total and CD45(−) exosomes from high stage compared to low stage patients. Furthermore, total and CD45(−) exosomes of high stage patients induced more apoptosis in CD8+ T cells than their low stage counterparts. CD69 suppression, a marker of reduced CD8+ T cell activation, was only mediated by CD45(−) exosomes. All fractions induced T_reg differentiation, defined by CD39 expression, but only CD45(−) exosomes showed a stage-dependent conversion. CD45(−) exosomes produced higher adenosine concentrations than CD45(+) exosomes, concluding that adenosine production measured in total exosomes mainly derives from TEX. The presented results show significant induction of immune suppression by TEX in HNSCC. This immunosuppressive effect supports the potential role of exosomes as liquid biomarkers for disease stage and level of immune suppression.

CD44v3 protein-carrying tumor-derived exosomes in HNSCC patients' plasma as potential noninvasive biomarkers of disease activity

The molecular cargo of tumor-cell-derived exosomes (TEX) mimics that of parental tumor cells. Thus, TEX could potentially serve as noninvasive biomarkers of cancer progression. However, separation of TEX from non-TEX in patients’ plasma requires tumor antigen-specific detection reagents. CD44v3 has been of interest as a potential biomarker of disease progression in HNSCC, because its overexpression in tumor cells associates with poor outcome. Here, CD44v3+ TEX immunocaptured from plasma of 44 HNSCC patients and 7 healthy donors (HDs) were evaluated as potential biomarkers of disease activity and stage. Exosomes were isolated from plasma of by size exclusion chromatography. Using anti-CD44v3 or anti-CD3 mAbs on beads, CD44v3+ TEX CD3(-)TEX-enriched exosomes were immunocaptured from supernatants of nonmalignant or HNSCC cell lines and from patients’ plasma. On-bead flow cytometry was used for the detection of FAS-L, PD-L1, TGFF-β. CSPG4 or EGFR on exosomes. The TEX expression profiles were correlated to clinicopathological parameters. Relative florescence intensity (RFI) values for CD44v3 were higher (p < .01) on TEX from HNSCC cell lines or on CD44v3+ CD3(-) plasma-derived exosomes. RFI values of CD44v3 on CD3(-) exosomes were higher (p < .005) in patients than in HDs and correlated (p < .05) with the UICC stage and lymph node metastasis. In HNSCC patients, CD44v3+ exosomes higher levels of immunosuppressive proteins compared to CD44v3(-) exosomes (p < .05-p < .005), and RFI values for these markers correlated with higher disease stages and lymph node metastasis. Isolation of CD44v3+ exosomes by immunocapture allowed for enrichment of TEX which are potentially promising liquid biomarkers of the tumor burden and disease stage in HNSCC.

Prostaglandin E2 signal inhibits T regulatory cell differentiation during allergic rhinitis inflammation through EP4 receptor

Objective

Allergic rhinitis (AR) is a common disease seriously affecting quality of life, and until now the effect of medical therapy is not satisfactory. It is essential to explore in depth the pathologic mechanism of AR to offer new ideas for developing novel treatment strategies. The defect of T regulatory (Treg) cells plays a critical role in the pathogenesis of AR, but the underlying mechanism remains to be elucidated. This study aims to determine the effect of Prostaglandin E2 (PGE2) on the differentiation of Treg cells in AR patients and the involvement of E prostanoid (EP) receptor signaling pathway.

Methods

The proportion of Treg cells and the level of PGE2 in the peripheral blood of AR patients and healthy controls were compared. Differentiation rate of Treg cells under the influence of various concentrations of PGE2 with or without diverse EP receptor agonists and antagonists were investigated through cell culture and flow cytometry in vitro. The cyclic AMP (cAMP) mimic or protein kinase B (Akt) inhibitor was also added to the culture to evaluate the downstream pathway of EP receptor signaling.

Results

The proportion of Treg cells decreased and PGE2 concentration increased in the peripheral blood of AR patients compared to healthy controls. PGE2 dose-dependently suppressed the differentiation of Treg cells from both human and mice naïve CD4⁺ T cells in vitro. This inhibitory effect was mediated through EP4 via a mechanism involving activation of cAMP-dependent proteinkinase A (PKA) signaling pathway.

Conclusion

PGE2-EP4-cAMP signaling might mediate the development of AR by inhibiting the differentiation of Treg cells.

The Prognostic Roles of Pretreatment Circulating Tumor Cells, Circulating Cancer Stem-Like Cells, and Programmed Cell Death-1 Expression on Peripheral Lymphocytes in Patients with Initially Unresectable, Recurrent or Metastatic Head and Neck Cancer: An Exploratory Study of Three Biomarkers in One-time Blood Drawing

Circulating tumor cells (CTCs) and immune status are strongly related to cancer prognosis, although few studies have examined both factors. This prospective observational study (ClinicalTrials.gov: NCT02420600) evaluated whether CTCs, circulating cancer stem-like cells (cCSCs), and peripheral lymphocytes with/without Programmed cell death protein 1 (PD-1) expression were associated with prognosis among patients receiving palliative chemotherapy for initially unresectable, recurrent/metastatic head and neck squamous cell carcinoma (rmHNSCC). Thirty-four patients were enrolled between January 2015 and June 2016. Overall survival (OS) was associated with a higher CTC number (hazard ratio [HR]: 1.01, p = 0.0004) and cCSC ratio (HR: 29.903, p < 0.0001). Progression-free survival (PFS) was also associated with CTC number (HR: 1.013, p = 0.002) and cCSC ratio (HR: 10.92, p = 0.003). A CD8⁺ proportion of ≥ 17% was associated with improved OS (HR: 0.242, p = 0.004). A CD4: CD8 ratio of >1.2 was associated with poorer trend of PFS (HR: 2.12, p = 0.064). PD-1 expression was not associated with survival outcomes. Baseline CTCs, cCSC ratio, and CD8⁺ ratio may predict prognosis in rmHNSCC.

Deciphering the Role of Regulatory CD4 T Cells in Oral and Oropharyngeal Cancer: A Systematic Review

Background: Recruiting regulatory CD4 T cells (Tregs) into the tumor microenvironment is an important tumor escape mechanism. Diminishing these suppressive cells is therefore one of the targets of cancer immunotherapy. Selective depletion of Tregs has proven successful in enhancing anti-tumor immunity and therapeutic efficacy in multiple tumor types. However, the role of Tregs in oral/oropharyngeal cancers is unclear with conflicting evidence regarding the effect of these suppressive cells on tumor prognosis. In this study, we sought to review the role of Tregs in oral/oropharyngeal cancer with the aim of deciphering the controversy regarding their effect on tumor progression and prognosis.

Methods: A systematic review of the literature pertaining to the role of Tregs in oral/oropharyngeal cancer was performed using Scopus, Embase, and PubMed. Forty-five records were deemed eligible and data describing methodology of Treg detection, tumor type, and association with prognosis were extracted.

Results: Of the 45 eligible manuscripts accepted for this systematic review, thirty-nine studies reported data from human subjects while the remaining studies focused on animal models. Sixteen studies were carried out using peripheral blood samples, while samples from the tumor site were analyzed in 18 studies and 11 studies assessed both blood and tumor samples. The transcriptional factor, Foxp3, was the most commonly used marker for Treg identification (38/45). The findings of 25 studies suggested that an increase in Tregs in the tumor microenvironment and/or peripheral blood was associated with poorer prognosis. These conclusions were attributed to the suppression of immune responses and the consequent tumor progression. Conversely, nine studies showed an increase in Tregs in peripheral blood and/or tumor microenvironment was related to a favorable prognosis, particularly in the presence of human papilloma virus (HPV), the status of which was only assessed in 11 studies.

Conclusions: This review underlines the importance of host immunity in the behavior of oral/oropharyngeal cancer. Furthermore, we report an apparent lack of clarity regarding the true role Tregs play in oral/oropharyngeal cancer progression which could be attributed to inconsistent detection techniques of Tregs. Our results therefore highlight the need for clearer methodologies and more robust phenotyping when defining Tregs.

Role of COX-2/PGE2 Mediated Inflammation in Oral Squamous Cell Carcinoma

A significant amount of research indicates that the cyclooxygenase/prostaglandin E2 (PGE2) pathway of inflammation contributes to the development and progression of a variety of cancers, including squamous cell carcinoma of the oral cavity and oropharynx (OSCC). Although there have been promising results from studies examining the utility of anti-inflammatory drugs in the treatment of OSCC, this strategy has been met with only variable success and these drugs are also associated with toxicities that make them inappropriate for some OSCC patients. Improved inflammation-targeting therapies require continued study of the mechanisms linking inflammation and progression of OSCC. In this review, a synopsis of OSCC biology will be provided, and recent insights into inflammation related mechanisms of OSCC pathobiology will be discussed. The roles of prostaglandin E2 and cluster of differentiation factor 147 (CD147) will be presented, and evidence for their interactions in OSCC will be explored. Through continued investigation into the protumourigenic pathways of OSCC, more treatment modalities targeting inflammation-related pathways can be designed with the hope of slowing tumour progression and improving patient prognosis in patients with this aggressive form of cancer.

FOXP3+ Treg as a therapeutic target for promoting anti-tumor immunity

INTRODUCTION

Regulatory T cells (Treg) characterized by expression of FOXP3 and strong immunosuppressive activity play a key role in regulating homeostasis in health and disease. Areas covered: Human Treg are highly diverse phenotypically and functionally. In the tumor microenvironment (TME), Treg are reprogrammed by the tumor, acquiring an activated phenotype and enhanced suppressor functions. No unique phenotypic markers for Treg accumulating in human tumors exist. Treg are heterogeneous and use numerous mechanisms to mediate suppression, which either silences anti-tumor immune surveillance or prevents tissue damage by activated T cells. Treg plasticity in the TME endows them with dual functionality. Treg frequency in tumors associates either with poor or improved survival. Treg responses to immune checkpoint inhibition (ICI) differ from the restorative effects ICIs induce in other immune cells. Therapies used to silence Treg, including ICIs, are only partly successful. Treg persistence and resistance to depletion are critical for maintaining homeostasis. Expert opinion: Treg emerge as a heterogeneous subset of immunosuppressive T cells, which usually, but not always, favor tumor progression. Treg are also engaged in non-immune activities that benefit the host. Therapeutic silencing of Treg in cancer requires a deeper understanding of Treg activities in human health and disease.

Clinical Significance of PD-L1+ Exosomes in Plasma of Head and Neck Cancer Patients

Purpose: The microenvironment of head and neck squamous cell carcinomas (HNSCC) is highly immunosuppressive. HNSCCs expressing elevated levels of PD-L1 have especially poor outcome. Exosomes that carry PD-L1 and suppress T-cell functions have been isolated from plasma of patients with HNSCC. The potential contributions of PD-L1⁺ exosomes to immune suppression and disease activity are evaluated.Experimental Design: Exosomes isolated from plasma of 40 HNSCC patients by size exclusion chromatography were captured on beads using anti-CD63 Abs, stained for PD-1 and PD-L1 and analyzed by flow cytometry. The percentages and mean fluorescence intensities (MFI) of PD-L1⁺ and PD-1⁺ exosome/bead complexes were correlated with the patients' clinicopathologic data. PD-L1^high or PD-L1^low exosomes were incubated with activated CD69⁺ human CD8⁺ T cells ± PD-1 inhibitor. Changes in CD69 expression levels on T cells were measured. Patients' plasma was tested for soluble PD-L1 (sPD-L1) by ELISA.Results: Levels of PD-L1 carried by exosomes correlated with patients' disease activity, the UICC stage and the lymph node status (P = 0.0008-0.013). In contrast, plasma levels of sPD-L1 or exosome PD-1 levels did not correlate with any clinicopathologic parameters. CD69 expression levels were inhibited (P < 0.03) by coincubation with PD-L1^high but not by PD-L1^low exosomes. Blocking of PD-L1⁺ exosome signaling to PD-1⁺ T cells attenuated immune suppression.Conclusions: PD-L1 levels on exosomes, but not levels of sPD-L1, associated with disease progression in HNSCC patients. Circulating PD-L1⁺ exosomes emerge as useful metrics of disease and immune activity in HNSCC patients.

SIGNIFICANCE

Circulating PD-L1^high exosomes in HNC patients' plasma but not soluble PD-L1 levels associate with disease progression. Clin Cancer Res; 24(4); 896-905. ©2017 AACR.

The Dual Role of Treg in Cancer

Regulatory T cells (Tregs) represent a small subpopulation of CD4⁺ cells. Tregs are characterized by the expression of transcription factor Forkhead box protein 3 (FoxP3), also known as scurfin. Tregs are modulators of adaptive immune responses and play an important role in maintaining tolerance to self-antigens, providing the suppression associated with tumour microenvironment as well. These immunomodulatory properties are the main reason for the development of numerous therapeutic strategies, designed to inhibit the activity of cancer cells. However, due to Treg subpopulation diversity and its many functional pathways, the role of these cells in the cancer development and progression is still not fully understood.

Analysis of gene expression profiling variations induced by hsa‑miR‑145‑5p‑overexpression in laryngeal squamous cell carcinoma cell line Tu‑177

The present study aimed to investigate the variations of the gene network and biological functions induced by hsa‑miR‑145‑5p in the laryngeal squamous cell carcinoma (LSCC) cell line Tu‑177. A hsa‑miR‑145‑5p‑overexpressed Tu‑177 cell model was established, and the gene expression microarray data of miR‑145‑5p‑overexpressed cells and negative control (NC) cells were analyzed. The differentially expressed genes (DEGs) between two groups were identified, and their potential functions were predicted by functional enrichment analysis. Furthermore, the targets of miR‑145‑5p were identified from the DEGs, and their potential functions and protein‑protein interactions (PPIs) were analyzed. The mRNA expressions of acetyl‑CoA carboxylase β (ACACB), fibroblast growth factor receptor 1 (FGFR1), protein phosphatase 3 catalytic subunit a (PPP3CA) and spleen associated tyrosine kinase (SYK), were analyzed via quantitative polymerase chain reaction. A total of 1,501 upregulated and 887 downregulated genes were identified in the hsa‑miR‑145‑5p‑overexpressed Tu‑177 cells, compared with the NC cells. Of these DEGs, 164 upregulated and 221 downregulated genes were predicted to be targeted by hsa‑miR‑145‑5p. The upregulated target genes were primarily associated with functions of immunity, whereas the downregulated target genes were significantly enriched in the p53 signaling pathway. In the PPI network consisting of 267 target genes, the upregulated ACACB had the greatest degree and interacted with downregulated genes including PPP3CA and SYK, in addition to upregulated genes, including FGFR1. The mRNA expressions of ACACB and FGFR1were markedly enhanced in miR‑145‑5p‑overexpressed Tu‑177 cells, whereas overexpressing miR‑145‑5p significantly reduced mRNA expression of PPP3CA and SYK. hsa‑miR‑145‑5p may exhibit an anticancer role in LSCC via regulating multiple cell processes, including cell proliferation and invasion, fatty acid metabolism, immunity and p53 signaling pathway. These findings provide novel information for the future investigation of miR‑145‑5p functions in LSCC.

Inhibition of CD8+ T cells and elimination of myeloid cells by CD4+ Foxp3- T regulatory type 1 cells in acute respiratory distress syndrome

Acute lung injury and acute respiratory distress syndrome (ARDS) are caused by rapid-onset bilateral pulmonary inflammation. We therefore investigated the potential role of interleukin (IL)-10⁺ CD4⁺ Tr1 cells, a regulatory T cell subset with previously identified immunosuppressive functions, in ARDS patients. We first showed that circulating Tr1 cells were upregulated in active and resolved ARDS patients compared to healthy controls and pneumonia patient controls. A significant fraction of these Tr1 cells expressed granzyme B and perforin, while most Tr1 cells did not express interferon gamma (IFN-γ), IL-4, IL-17 or FOXP3, suggesting that the effector functions of these Tr1 cells were primarily mediated by IL-10, granzyme B, and perforin. Indeed, Tr1 cells effectively suppressed CD8⁺ T cell IFN-γ production and induced lysis of monocytes and dendritic cells in vitro. The elimination of myeloid antigen-presenting cells depended on granzyme B production. We also discovered that Tr1 cells could be identified in the bronchoalveolar lavage fluid collected from ARDS patients. All these results suggested that Tr1 cells possessed the capacity to downregulate inflammation in ARDS. In support of this, we found that ARDS patients who resolved the inflammation and survived the syndrome contained significantly higher levels of Tr1 cells than ARDS patients who succumbed to the syndrome. Overall, this report added a novel piece of evidence that ARDS could be intervened by regulatory T cell-mediated suppressive mechanisms.

Suppression of Lymphocyte Functions by Plasma Exosomes Correlates with Disease Activity in Patients with Head and Neck Cancer

Purpose: Head and neck cancers (HNCs) often induce profound immunosuppression, which contributes to disease progression and interferes with immune-based therapies. Body fluids of patients with HNC are enriched in exosomes potentially engaged in negative regulation of antitumor immune responses. The presence and content of exosomes derived from plasma of patients with HNC are evaluated for the ability to induce immune dysfunction and influence disease activity.Experimental Design: Exosomes were isolated by size-exclusion chromatography from plasma of 38 patients with HNC and 14 healthy donors. Morphology, size, numbers, and protein and molecular contents of the recovered exosomes were determined. Coculture assays were performed to measure exosome-mediated effects on functions of normal human lymphocyte subsets and natural killer (NK) cells. The results were correlated with disease stage and activity.Results: The presence, quantity, and molecular content of isolated, plasma-derived exosomes discriminated patients with HNC with active disease (AD) from those with no evident disease (NED) after oncologic therapies. Exosomes of patients with AD were significantly more effective than exosomes of patients with NED in inducing apoptosis of CD8⁺ T cells, suppression of CD4⁺ T-cell proliferation, and upregulation of regulatory T-cell (Treg) suppressor functions (all at P < 0.05). Exosomes of patients with AD also downregulated NKG2D expression levels in NK cells.Conclusions: Exosomes in plasma of patients with HNC carry immunosuppressive molecules and interfere with functions of immune cells. Exosome-induced immune suppression correlates with disease activity in HNC, suggesting that plasma exosomes could be useful as biomarkers of HNC progression. Clin Cancer Res; 23(16); 4843-54. ©2017 AACR.

Prostaglandin E2 As a Modulator of Viral Infections

Viral infections are a major cause of infectious diseases worldwide. Inflammation and the immune system are the major host defenses against these viral infection. Prostaglandin E2 (PGE2), an eicosanoid generated by cyclooxygenases, has been shown to modulate inflammation and the immune system by regulating the expression/concentration of cytokines. The effect of PGE2 on viral infection and replication is cell type- and virus-family-dependent. The host immune system can be modulated by PGE2, with regards to immunosuppression, inhibition of nitrogen oxide (NO) production, inhibition of interferon (IFN) and apoptotic pathways, and inhibition of viral receptor expression. Furthermore, PGE2 can play a role in viral infection directly by increasing the production and release of virions, inhibiting viral binding and replication, and/or stimulating viral gene expression. PGE2 may also have a regulatory role in the induction of autoimmunity and in signaling via Toll-like receptors. In this review the known effects of PGE2 on the pathogenesis of various infections caused by herpes simplex virus, rotavirus, influenza A virus and human immunodeficiency virus as well the therapeutic potential of PGE2 are discussed.

CD4+Foxp3-IL-10+ Tr1 Cells Promote Relapse of Diffuse Large B Cell Lymphoma by Enhancing the Survival of Malignant B Cells and Suppressing Antitumor T Cell Immunity

Diffuse large B cell lymphoma (DLBCL) is a common B cell malignancy. Complete remission can be achieved in most patients by conventional treatment with rituximab and chemotherapy. However, a subset of remission individuals will develop a relapsed disease for obscure reasons. CD4⁺Foxp3^-IL-10⁺ cell (Tr1) is a novel cell subtype with the capacity to suppress pro-inflammatory responses, but has not been extensively studied in most tumors. In this study, we investigated the potential role of Tr1 cells in DLBCL. We found that compared to that in healthy controls, the frequency of Tr1 cells was significantly increased in DLBCL patients, even during complete remission. Further study showed that these Tr1 cells were enriched in the CD25^low/-Foxp3^-CD49b⁺LAG-3⁺ fraction and could be developed in vitro from naive CD45RA⁺ CD4⁺ T cells. To examine the effect of Tr1 upregulation, we cocultured the enriched in vitro-induced Tr1 cells (iTr1) with autologous primary DLBCL cells and CD3⁺ T cells and found that iTr1 cells both enhanced the survival of CD20⁺ DLBCL tumor cells and suppressed the antitumor response of CD3⁺ T cells through the production of IL-10. Furthermore, the frequency of CD4⁺Foxp3^-IL-10⁺ Tr1 cells in DLBCL patients during complete remission is directly associated with the risk of relapse. Together, these results suggested that Tr1 cells contributed to tumor cell maintenance and may serve as a prognostic marker and therapeutic target.

Molecular Mechanisms for cAMP-Mediated Immunoregulation in T cells - Role of Anchored Protein Kinase A Signaling Units

The cyclic AMP/protein kinase A (cAMP/PKA) pathway is one of the most common and versatile signal pathways in eukaryotic cells. A-kinase anchoring proteins (AKAPs) target PKA to specific substrates and distinct subcellular compartments providing spatial and temporal specificity for mediation of biological effects channeled through the cAMP/PKA pathway. In the immune system, cAMP is a potent negative regulator of T cell receptor-mediated activation of effector T cells (Teff) acting through a proximal PKA/Csk/Lck pathway anchored via a scaffold consisting of the AKAP Ezrin holding PKA, the linker protein EBP50, and the anchoring protein phosphoprotein associated with glycosphingolipid-enriched microdomains holding Csk. As PKA activates Csk and Csk inhibits Lck, this pathway in response to cAMP shuts down proximal T cell activation. This immunomodulating pathway in Teff mediates clinically important responses to regulatory T cell (Treg) suppression and inflammatory mediators, such as prostaglandins (PGs), adrenergic stimuli, adenosine, and a number of other ligands. A major inducer of T cell cAMP levels is PG E2 (PGE2) acting through EP2 and EP4 prostanoid receptors. PGE2 plays a crucial role in the normal physiological control of immune homeostasis as well as in inflammation and cancer immune evasion. Peripherally induced Tregs express cyclooxygenase-2, secrete PGE2, and elicit the immunosuppressive cAMP pathway in Teff as one tumor immune evasion mechanism. Moreover, a cAMP increase can also be induced by indirect mechanisms, such as intercellular transfer between T cells. Indeed, Treg, known to have elevated levels of intracellular cAMP, may mediate their suppressive function by transferring cAMP to Teff through gap junctions, which we speculate could also be regulated by PKA/AKAP complexes. In this review, we present an updated overview on the influence of cAMP-mediated immunoregulatory mechanisms acting through localized cAMP signaling and the therapeutical increasing prospects of AKAPs disruptors in T-cell immune function.

Induction of regulatory T cells: A role for probiotics and prebiotics to suppress autoimmunity

Regulatory T cells (Tregs) are comprised of a heterogeneous population of cells that play a vital role in suppressing inflammation and maintaining immune tolerance. Given the crucial role of Tregs in maintaining immune homeostasis, it is probably not surprising that many microbial species and their metabolites have the potential to induce Tregs. There is now great interest in the therapeutic potential of probiotics and prebiotics based strategies for a range of autoimmune disorders. This review will summarise recent findings concerning the role of probiotics and prebiotics in induction of Tregs to ameliorate the autoimmune conditions. In addition, the article is focused to explain the different mechanisms of Treg induction and function by these probiotics and prebiotics, based on the available studies till date. The article further proposes that induction of Tregs by probiotics and prebiotics could lead to the development of new therapeutic approach towards curbing the autoimmune response and as an alternative to detrimental immunosuppressive drugs.

Until Death Do Us Part: Necrosis and Oxidation Promote the Tumor Microenvironment

Tumor proliferation is concomitant with autophagy, limited apoptosis, and resultant necrosis. Necrosis is associated with the release of damage-associated molecular pattern molecules (DAMPs), which act as 'danger signals', recruiting inflammatory cells, inducing immune responses, and promoting wound healing. Most of the current treatment strategies for cancer (chemotherapy, radiation therapy, hormonal therapy) promote DAMP release following therapy-induced tumor death by necroptosis and necrosis. Myeloid cells (monocytes, dendritic cells (DCs), and granulocytes), as well as mesenchymal stromal cells (MSCs) belong to the early immigrants in response to unscheduled cell death, initiating and modulating the subsequent inflammatory response. Responding to DAMPs, MSCs, and DCs promote an immunosuppressive milieu, while eosinophils induce oxidative conditions limiting the biologic activity of DAMPs over time and distance. Regulatory T cells are strongly affected by pattern recognition receptor signaling in the tumor microenvironment and limit immune reactivity coordinately with myeloid-derived suppressor cells. Means to 'aerobically' oxidize DAMPs provide a novel strategy for limiting tumor progression. The present article summarizes our current understanding of the impact of necrosis on the tumor microenvironment and the influence of oxidative conditions found within this setting.

Repurposing Drugs in Oncology (ReDO)-diclofenac as an anti-cancer agent

Diclofenac (DCF) is a well-known and widely used non-steroidal anti-inflammatory drug (NSAID), with a range of actions which are of interest in an oncological context. While there has long been an interest in the use of NSAIDs in chemoprevention, there is now emerging evidence that such drugs may have activity in a treatment setting. DCF, which is a potent inhibitor of COX-2 and prostaglandin E2 synthesis, displays a range of effects on the immune system, the angiogenic cascade, chemo- and radio-sensitivity and tumour metabolism. Both pre-clinical and clinical evidence of these effects, in multiple cancer types, is assessed and summarised and relevant mechanisms of action outlined. Based on this evidence the case is made for further clinical investigation of the anticancer effects of DCF, particularly in combination with other agents - with a range of possible multi-drug and multi-modality combinations outlined in the supplementary materials accompanying the main paper.

Comparative analysis of CD4+ and CD8+ T cells in tumor tissues, lymph nodes and the peripheral blood from patients with breast cancer

Background: CD4+ and CD8+ T cells are the main types of lymphocytes in cell-mediated immunity and play a central role in the induction of efficient immune responses against tumors. The frequencies of T cell subtypes in the peripheral blood and tumor tissues, and draining lymph nodes (dLN) can be considered as useful markers for evaluation of the immune system in cancers. Methods: In this study, the frequencies of CD4+ and CD8+ T cells in blood, tumor tissues, and dLN samples of breast cancer patients were compared with each other and with similar tissues from normal individuals. Immunophenotyping was carried out by flow cytometry and the expression levels of CXCL10, granzyme B, and mammaglobin were evaluated by real-time PCR. Results: In the peripheral blood, there were no differences in the T cell subsets between the patients and the normal individuals. The frequency of CD8+ T cells was significantly higher in tumor tissue than normal breast tissues while granzyme B expression was similar. Based on mammaglobin expression levels, dLN have been classified into micro- and macro-metastatic dLN. We found significantly lower frequency of CD4+ in macro-metastatic dLN than micro-metastatic dLN. CD8+ frequency was similar in both dLN; however, granzyme B expression was higher in micro-metastatic ones. There was not any significant difference in CXCL10 expression between the two types of dLN. Conclusion: Based on our results, although the tumor does not affect the systemic immunity, tumoral cells affect the local immune system in the tumoral tissues and the metastatic dLN.

Peripheral natural killer cell and allo-stimulated T-cell function in kidney transplant recipients associate with cancer risk and immunosuppression-related complications

Reducing immunosuppression has been proposed as a means of preventing cancer in kidney transplant recipients but this can precipitate graft rejection. Here we tested whether anti-tumor natural killer (NK) cell and allo-responsive T-cell function in kidney transplant recipients may predict cancer risk and define risk of rejection. NK cell function was measured by the release of lactate dehydrogenase and T-cell allo-response by interferon-γ quantification using a panel of reactive T-cell enzyme-linked immunospot (ELISPOT) in 56 kidney transplant recipients with current or past cancer and 26 kidney transplant recipients without cancer. NK function was significantly impaired and the allo-response was significantly lower in kidney transplant recipients with cancer. With prospective follow-up, kidney transplant recipients with poor NK cell function had a hazard ratio of 2.1 (95% confidence interval 0.97-5.00) for the combined end point of metastatic cancer, cancer-related death, or septic death. Kidney transplant recipients with low interferon-γ release were also more likely to reach this combined end point. Thus, posttransplant monitoring of allo-immunity and NK cell function is useful for assessing the risk of over immunosuppression for the development of malignancy and/or death from cancer or sepsis.

The role of regulatory T cells in cancer immunology

Regulatory T cells (Treg) are generally considered to be significant contributors to tumor escape from the host immune system. Emerging evidence suggests, however, that in some human cancers, Treg are necessary to control chronic inflammation, prevent tissue damage, and limit inflammation-associated cancer development. The dual role of Treg in cancer and underpinnings of Treg diversity are not well understood. This review attempts to provide insights into the importance of Treg subsets in cancer development and its progression. It also considers the role of Treg as potential biomarkers of clinical outcome in cancer. The strategies for monitoring Treg in cancer patients are discussed as is the need for caution in the use of therapies which indiscriminately ablate Treg. A greater understanding of molecular pathways operating in various tumor microenvironments is necessary for defining the Treg impact on cancer and for selecting immunotherapies targeting Treg.

Type 1 regulatory T cells: a new mechanism of peripheral immune tolerance

The lack of immune response to an antigen, a process known as immune tolerance, is essential for the preservation of immune homeostasis. To date, two mechanisms that drive immune tolerance have been described extensively: central tolerance and peripheral tolerance. Under the new nomenclature, thymus-derived regulatory T (tT(reg)) cells are the major mediators of central immune tolerance, whereas peripherally derived regulatory T (pT(reg)) cells function to regulate peripheral immune tolerance. A third type of T(reg) cells, termed iT(reg), represents only the in vitro-induced T(reg) cells(1). Depending on whether the cells stably express Foxp3, pT(reg), and iT(reg) cells may be divided into two subsets: the classical CD4(+)Foxp3(+) T(reg) cells and the CD4(+)Foxp3(-) type 1 regulatory T (Tr1) cells(2). This review focuses on the discovery, associated biomarkers, regulatory functions, methods of induction, association with disease, and clinical trials of Tr1 cells.

(Compl)Ex-Th17-Treg cell inter-relationship

Codependent development and Th17-to-FoxP3⁺ T cell inter-conversion account for the enigmatic coexistence of IL17-producing and FoxP3⁺ cells in tumor-associated inflammation. In addition to T_reg cells, exTh17-FoxP3⁺ cells present a novel subpopulation of FoxP3⁺ cells. Yin-yang of IL17⁺ and FoxP3⁺ cells presents an important principle for improved approaches in cancer immunotherapy.

IL-10 and ARG-1 concentrations in bone marrow and peripheral blood of metastatic neuroblastoma patients do not associate with clinical outcome

The expression of the immunosuppressive molecules IL-10 and arginase 1 (ARG-1), and of FOXP3 and CD163, as markers of regulatory T cells (Treg) and macrophages, respectively, was evaluated in bone marrow (BM) and peripheral blood (PB) samples collected at diagnosis from patients with metastatic neuroblastoma (NB). IL-10 and ARG-1 plasma concentrations were measured and the association of each parameter with patients' outcome was tested. The percentages of immunosuppressive Treg and type-1 regulatory (Tr1) cells were also determined. In both BM and PB samples, IL-10 mRNA expression was higher in metastatic NB patients than in controls. IL-10 plasma concentration was higher in patients with NB regardless of stage. Neither IL-10 expression nor IL-10 plasma concentration significantly associated with patient survival. In PB samples from metastatic NB patients, ARG-1 and CD163 expression was higher than in controls but their expression did not associate with survival. Moreover, ARG-1 plasma concentration was lower than in controls, and no association with patient outcome was found. Finally, in metastatic NB patients, the percentage of circulating Treg was higher than in controls, whereas that of Tr1 cells was lower. In conclusion, although IL-10 concentration and Treg percentage were increased, their contribution to the natural history of metastatic NB appears uncertain.

Tumor-infiltrating plasmacytoid dendritic cells promote immunosuppression by Tr1 cells in human liver tumors

CD4⁺ type 1 T regulatory (Tr1) cells have a crucial role in inducing tolerance. Immune regulation by these cells is mainly mediated through the secretion of high amounts of IL-10. Several studies have suggested that this regulatory population may be involved in tumor-mediated immune-suppression. However, direct evidence of a role for Tr1 cells in human solid tumors is lacking. Using ex vivo isolated cells from individuals with hepatocellular carcinoma (HCC; n = 39) or liver metastases from colorectal cancer (LM-CRC; n = 60) we identify a CD4⁺FoxP3^-IL-13^-IL-10⁺ T cell population in tumors of individuals with primary or secondary liver cancer that is characterized as Tr1 cells by the expression of CD49b and the lymphocyte activation gene 3 (LAG-3) and strong suppression activity of T cell responses in an IL-10 dependent manner. Importantly, the presence of tumor-infiltrating Tr1 cells is correlated with tumor infiltration of plasmacytoid dendritic cells (pDCs). pDCs exposed to tumor-derived factors enhance IL-10 production by Tr1 cells through up-regulation of the inducible co-stimulatory ligand (ICOS-L). These findings suggest a role for pDCs and ICOS-L in promoting intra-tumoral immunosuppression by Tr1 cells in human liver cancer, which may foster tumor progression and which might interfere with attempts of immunotherapeutic intervention.

Immune profiling and cancer post transplantation

Half of all long-term (> 10 year) australian kidney transplant recipients (KTR) will develop squamous cell carcinoma (SCC) or solid organ cancer (SOC), making cancer the leading cause of death with a functioning graft. At least 30% of KTR with a history of SCC or SOC will develop a subsequent SCC or SOC lesion. Pharmacological immunosuppression is a major contributor of the increased risk of cancer for KTR, with the cancer lesions themselves further adding to systemic immunosuppression and could explain, in part, these phenomena. Immune profiling includes; measuring immunosuppressive drug levels and pharmacokinetics, enumerating leucocytes and leucocyte subsets as well as testing leucocyte function in either an antigen specific or non-specific manner. Outputs can vary from assay to assay according to methods used. In this review we define the rationale behind post-transplant immune monitoring assays and focus on assays that associate and/or have the ability to predict cancer and rejection in the KTR. We find that immune monitoring can identify those KTR of developing multiple SCC lesions and provide evidence they may benefit from pharmacological immunosuppressive drug dose reductions. In these KTR risk of rejection needs to be assessed to determine if reduction of immunosuppression will not harm the graft.

Clinical Impact of Regulatory T cells (Treg) in Cancer and HIV

The role of regulatory T cells, (Treg) in human cancer and HIV-1 infections has been under intense scrutiny. While the lack of a marker specific for human Treg has made it challenging to phenotype these cells, combinations of several markers and functional attributes of Treg have made it possible to assess their contributions to immune homeostasis in health and disease. Treg diversity and their plasticity create a challenge in deciding whether they are beneficial to the host by down-regulating excessive immune activation or are responsible for adverse effects such as suppression of anti-tumor immune responses resulting in promotion of tumor growth. Treg are emerging as active participants in several biochemical pathways involved in immune regulation. This review attempts to integrate current information about human Treg in respect to their activities in cancer and HIV-1. The goal is to evaluate the potential of Treg as targets for future immune or pharmacologic therapies for cancer or HIV-1 infections.

Human CD4+ CD39+ regulatory T cells produce adenosine upon co-expression of surface CD73 or contact with CD73+ exosomes or CD73+ cells

While murine CD4(+) CD39(+) regulatory T cells (T(reg)) co-express CD73 and hydrolyze exogenous (e) adenosine triphosphate (ATP) to immunosuppressive adenosine (ADO), surface co-expression of CD73 on human circulating CD4(+) CD39(+) T(reg) is rare. Therefore, the ability of human T(reg) to produce and utilize ADO for suppression remains unclear. Using mass spectrometry, we measured nucleoside production by subsets of human CD4(+) CD39(+) and CD4(+) CD39(-)CD73(+) T cells or CD19(+) B cells isolated from blood of 30 volunteers and 14 cancer patients. CD39 and CD73 expression was evaluated by flow cytometry, Western blots, confocal microscopy or reverse transcription-polymerase chain reaction (RT-PCR). Circulating CD4(+) CD39(+) T(reg) which hydrolyzed eATP to 5'-AMP contained few intracytoplasmic granules and had low CD73 mRNA levels. Only ∼1% of these T(reg) were CD39(+) CD73(+) . In contrast, CD4(+) CD39(neg) CD73(+) T cells contained numerous CD73(+) granules in the cytoplasm and strongly expressed surface CD73. In vitro-generated T(reg) (Tr1) and most B cells were CD39(+) CD73(+) . All these CD73(+) T cell subsets and B cells hydrolyzed 5'-AMP to ADO. Exosomes isolated from plasma of normal control (NC) or cancer patients carried enzymatically active CD39 and CD73(+) and, when supplied with eATP, hydrolyzed it to ADO. Only CD4(+) CD39(+) T(reg) co-incubated with CD4(+) CD73(+) T cells, B cells or CD39(+) CD73(+) exosomes produced ADO. Thus, contact with membrane-tethered CD73 was sufficient for ADO production by CD4(+) CD39(+) T(reg). In microenvironments containing CD4(+) CD73(+) T cells, B cells or CD39(+) CD73(+) exosomes, CD73 is readily available to CD4(+) CD39(+) CD73(neg) T(reg) for the production of immunosuppressive ADO.

Induced regulatory T cells in inhibitory microenvironments created by cancer

INTRODUCTION

Regulatory T cells (Tregs) accumulating in the peripheral circulation and tumor sites of patients contribute to tumor escape from the host immune system. Tregs encompass subsets of immune cells with distinct phenotypic and functional properties. Whereas natural (n) or thymic-derived (t) Tregs regulate responses to self-antigens, inducible (i) or peripheral (p) Tregs generated and expanded in regulatory microenvironments control immune responses to a broad variety of antigens.

AREAS COVERED

Tregs accumulating in the tumor microenvironment (TME) are contextually regulated. They acquire phenotypic and functional attributes imposed by the inhibitory molecular pathways operating in situ. Several molecular pathways active in human cancer are reviewed. The pathways may differ from one tumor to another, and environmentally induced Tregs may be functionally distinct. Potential therapeutic strategies for selective silencing of iTregs are considered in the light of the newly acquired understanding of their phenotypic and functional diversity.

EXPERT OPINION

Human Tregs accumulating in cancer comprise 'bad' subsets, which inhibit antitumor immunity, and 'good' anti-inflammatory subsets, which maintain tolerance to self and benefit the host. Future therapeutic strategies targeting Tregs will need to discriminate between these Treg subsets and will need to consider reprogramming strategies instead of Treg elimination. Re-establishment of effective antitumor immune responses in cancer patients without disturbing a normal homeostatic T-cell balance will greatly benefit from insights into inhibitory pathways engaged by human tumors.

Stromal reengineering to treat pancreas cancer

Pancreatic ductal adenocarcinoma co-opts multiple cellular and extracellular mechanisms to create a complex cancer organ with an unusual proclivity for metastasis and resistance to therapy. Cell-autonomous events are essential for the initiation and maintenance of pancreatic ductal adenocarcinoma, but recent studies have implicated critical non-cell autonomous processes within the robust desmoplastic stroma that promote disease pathogenesis and resistance. Thus, non-malignant cells and associated factors are culprits in tumor growth, immunosuppression and invasion. However, even this increasing awareness of non-cell autonomous contributions to disease progression is tempered by the conflicting roles stromal elements can play. A greater understanding of stromal complexity and complicity has been aided in part by studies in highly faithful genetically engineered mouse models of pancreatic ductal adenocarcinoma. Insights gleaned from such studies are spurring the development of therapies designed to reengineer the pancreas cancer stroma and render it permissive to agents targeting cell-autonomous events or to reinstate immunosurveillance. Integrating conventional and immunological treatments in the context of stromal targeting may provide the key to a durable clinical impact on this formidable disease.

Phase I dendritic cell p53 peptide vaccine for head and neck cancer

BACKGROUND

p53 accumulation in head and neck squamous cell carcinoma (HNSCC) cells creates a targetable tumor antigen. Adjuvant dendritic cell (DC)-based vaccination against p53 was tested in a phase I clinical trial.

EXPERIMENTAL METHODS

Monocyte-derived DC from 16 patients were loaded with two modified HLA-class I p53 peptides (Arm 1), additional Th tetanus toxoid peptide (Arm 2), or additional Th wild-type (wt) p53-specific peptide (Arm 3). Vaccine DCs (vDC) were delivered to inguinal lymph nodes at three time points. vDC phenotype, circulating p53-specific T cells, and regulatory T cells (Treg) were serially monitored by flow cytometry and cytokine production by Luminex. vDC properties were compared with those of DC1 generated with an alternative maturation regimen.

RESULTS

No grade II-IV adverse events were observed. Two-year disease-free survival of 88% was favorable. p53-specific T-cell frequencies were increased postvaccination in 11 of 16 patients (69%), with IFN-γ secretion detected in four of 16 patients. Treg frequencies were consistently decreased (P = 0.006) relative to prevaccination values. The phenotype and function of DC1 were improved relative to vDC.

CONCLUSION

Adjuvant p53-specific vaccination of patients with HNSCC was safe and associated with promising clinical outcome, decreased Treg levels, and modest vaccine-specific immunity. HNSCC patients' DC required stronger maturation stimuli to reverse immune suppression and improve vaccine efficacy.

The challenge of pancreatic cancer therapy and novel treatment strategy using engineered mesenchymal stem cells

Mesenchymal stem cells (MSCs) have attracted significant attention in cancer research as a result of their accessibility, tumor-oriented homing capacity, and the feasibility of auto-transplantation. This review provides a comprehensive overview of current challenges in pancreatic cancer therapy, and we propose a novel strategy for using MSCs as means of delivering anticancer genes to the site of pancreas. We aim to provide a practical platform for the development of MSC-based therapy for pancreatic cancer.

Cancer immunotherapy: accomplishments to date and future promise

Cancer remains a devastating disease as existing therapies are too often ineffective and toxicities remain unacceptably high. Immunotherapies for cancer offer the promise of the specificity and memory of the immune system against malignant cells to achieve durable cure with minimal toxicity. Beginning with the success of bone marrow transplantation for blood-borne cancers, and the more recent development of monoclonal antibody therapeutics for a variety of tumors, immunotherapies are already among the most successful class of treatments for cancer. Greater understanding of immunoregulatory mechanisms and improved techniques for immune cell manipulation and engineering have led to new immunomodulatory approaches and cell-based therapies for cancer that have generated great excitement within the biomedical community. As these technologies continue to improve, and as new approaches for harnessing the power and specificity of the immune system are developed, immunotherapies will play an increasingly important role in the treatment of cancer. Here, we review the history of immunotherapies for cancer and discuss existing and emerging immunotherapy technologies that hope to translate the promise of immunotherapy into clinical reality.