Tumor Evasion of the Immune System by Converting CD4+CD25− T Cells into CD4+CD25+ T Regulatory Cells: Role of Tumor-Derived TGF-β

Therapeutic targeting of TGF-β in lung cancer

Transforming growth factor-β (TGF-β) plays a complex role in lung cancer pathophysiology, initially acting as a tumor suppressor by inhibiting early-stage tumor growth. However, its role evolves in the advanced stages of the disease, where it contributes to tumor progression not by directly promoting cell proliferation but by enhancing epithelial-mesenchymal transition (EMT) and creating a conducive tumor microenvironment. While EMT is typically associated with enhanced migratory and invasive capabilities rather than proliferation per se, TGF-β's influence on this process facilitates the complex dynamics of tumor metastasis. Additionally, TGF-β impacts the tumor microenvironment by interacting with immune cells, a process influenced by genetic and epigenetic changes within tumor cells. This interaction highlights its role in immune evasion and chemoresistance, further complicating lung cancer therapy. This review provides a critical overview of recent findings on TGF-β's involvement in lung cancer, its contribution to chemoresistance, and its modulation of the immune response. Despite the considerable challenges encountered in clinical trials and the development of new treatments targeting the TGF-β pathway, this review highlights the necessity for continued, in-depth investigation into the roles of TGF-β. A deeper comprehension of these roles may lead to novel, targeted therapies for lung cancer. Despite the intricate behavior of TGF-β signaling in tumors and previous challenges, further research could yield innovative treatment strategies.

New expression of PD-L1 on activated CD4+ T cells opens up new opportunities for cell interactions and signaling

Surface expression of programmed death-ligand 1 (PD-L1) is mainly observed on antigen presenting cells (APC) such as monocytes or dendritic cells (DCs). Our results showing a high expression of PD-L1 on human naïve CD4+ effector T-cells (TEFFs) and CD4+ regulatory T cells (TREGs) after activation with human DCs, allow us to propose a new role for PD-L1 and its ligands and their potential impact on new signaling pathways. Indeed, expression of PD-L1 on activated CD4+T cells could allow cis interaction with its ligands such as PD-1 and CD80, thus disrupting interactions with other signaling receptors, such as cytotoxic T-lymphocyte antigen-4 (CTLA-4) or CD28, which interact with CD80. The ability to compete with hypothetical configuration modifications that may cause a change in affinity/avidity for the trans and cis interactions between these proteins expressed on T cells and/or DCs is discussed. As the study of cancer is strongly influenced by the role of the PD-L1/PD-1 pathway and CD4+T cells, new interactions, cis and/or trans, between TEFFs, TREGs and tumor cells are also proposed. The presence of PD-L1 on activated CD4+ T cells could influence the quality of the cytotoxic T lymphocyte response during priming to provide other help signals.

Generation of an Inhibitory NK Cell Subset by TGF-β1/IL-15 Polarization

NK cells have been shown to exhibit inflammatory and immunoregulatory functions in a variety of healthy and diseased settings. In the context of chronic viral infection and cancer, distinct NK cell populations that inhibit adaptive immune responses have been observed. To understand how these cells arise and further characterize their immunosuppressive role, we examined in vitro conditions that could polarize human NK cells into an inhibitory subset. TGF-β1 has been shown to induce regulatory T cells in vitro and in vivo; we therefore investigated if TGF-β1 could also induce immunosuppressive NK-like cells. First, we found that TGF-β1/IL-15, but not IL-15 alone, induced CD103+CD49a+ NK-like cells from peripheral blood NK cells, which expressed markers previously associated with inhibitory CD56+ innate lymphoid cells, including high expression of GITR and CD101. Moreover, supernatant from ascites collected from patients with ovarian carcinoma also induced CD103+CD49a+ NK-like cells in vitro in a TGF-β-dependent manner. Interestingly, TGF-β1/IL-15-induced CD103+CD56+ NK-like cells suppressed autologous CD4+ T cells in vitro by reducing absolute number, proliferation, and expression of activation marker CD25. Collectively, these findings provide new insight into how NK cells may acquire an inhibitory phenotype in TGF-β1-rich environments.

Innate immune cells: Key players of orchestra in modulating tumor microenvironment (TME)

The tumor microenvironment (TME) with vital role in cancer progression is composed of various cells such as endothelial cells, immune cells, and mesenchymal stem cells. In particular, innate immune cells such as macrophages, dendritic cells, myeloid-derived suppressor cells, neutrophils, innate lymphoid cells, γδT lymphocytes, and natural killer cells can either promote or suppress tumor progression when present in the TME. An increase in research on the cross-talk between the TME and innate immune cells will lead to new approaches for anti-tumoral therapeutic interventions. This review primarily focuses on the biology of innate immune cells and their main functions in the TME. In addition, it summarizes several innate immune-based immunotherapies that are currently tested in clinical trials.

It Takes Two to Tango: The Interplay between Prostate Cancer and Its Microenvironment from an Epigenetic Perspective

Prostate cancer is the second most common cancer in men worldwide and is associated with high morbidity and mortality. Consequently, there is an urgent unmet need for novel treatment avenues. In addition to somatic genetic alterations, deviations in the epigenetic landscape of cancer cells and their tumor microenvironment (TME) are critical drivers of prostate cancer initiation and progression. Unlike genomic mutations, epigenetic modifications are potentially reversible. Therefore, the inhibition of aberrant epigenetic modifications represents an attractive and exciting novel treatment strategy for castration-resistant prostate cancer patients. Moreover, drugs targeting the epigenome also exhibit synergistic interactions with conventional therapeutics by directly enhancing their anti-tumorigenic properties by "priming" the tumor and tumor microenvironment to increase drug sensitivity. This review summarizes the major epigenetic alterations in prostate cancer and its TME, and their involvement in prostate tumorigenesis, and discusses the impact of epigenome-targeted therapies.

A new target of radiotherapy combined with immunotherapy: regulatory T cells

Radiotherapy is one important treatment for malignant tumours. It is widely believed today that radiotherapy has not only been used as a local tumour treatment method, but also can induce systemic anti-tumour responses by influencing the tumour microenvironment, but its efficacy is limited by the tumour immunosuppression microenvironment. With the advancement of technology, immunotherapy has entered a golden age of rapid development, gradually occupying a place in clinical tumour treatment. Regulatory T cells (Tregs) widely distributing in the tumour microenvironment play an important role in mediating tumour development. This article analyzes immunotherapy, the interaction between Tregs, tumours and radiotherapy. It briefly introduces immunotherapies targeting Tregs, aiming to provide new strategies for radiotherapy combined with Immunotherapy.

FLT3L-dependent dendritic cells control tumor immunity by modulating Treg and NK cell homeostasis

FLT3-L-dependent classical dendritic cells (cDCs) recruit anti-tumor and tumor-protecting lymphocytes. We evaluate cancer growth in mice with low, normal, or high levels of cDCs. Paradoxically, both low or high numbers of cDCs improve survival in mice with melanoma. In low cDC context, tumors are restrained by the adaptive immune system through influx of effector T cells and depletion of Tregs and NK cells. High cDC numbers favor the innate anti-tumor response, with massive recruitment of activated NK cells, despite high Treg infiltration. Anti CTLA-4 but not anti PD-1 therapy synergizes with FLT3-L therapy in the cDCHi but not in the cDCLo context. A combination of cDC boost and Treg depletion dramatically improves survival of tumor-bearing mice. Transcriptomic data confirm the paradoxical effect of cDC levels on survival in several human tumor types. cDCHi-TregLo state in such patients predicts best survival. Modulating cDC numbers via FLT3 signaling may have therapeutic potential in human cancer.

Breast cancer stem cells generate immune-suppressive T regulatory cells by secreting TGFβ to evade immune-elimination

Cancer stem cells (CSCs), being the primary contributors in tumor initiation, metastasis, and relapse, ought to have seminal roles in evasion of immune surveillance. Tumor-promoting CD4+CD25+FOXP3+ T-regulatory cells (Tregs) have been described to abolish host defense mechanisms by impeding the activities of other immune cells including effector T cells. However, whether CSCs can convert effector T cells to immune-suppressive Treg subset, and if yes, the mechanism underlying CSC-induced Treg generation, are limitedly studied. In this regard, we observed a positive correlation between breast CSC and Treg signature markers in both in-silico and immunohistochemical analyses. Mirroring the conditions during tumor initiation, low number of CSCs could successfully generate CD4+CD25+FOXP3+ Treg cells from infiltrating CD4+ T lymphocytes in a contact-independent manner. Suppressing the proliferation potential as well as IFNγ production capacity of effector T cells, these Treg cells might be inhibiting antitumor immunity, thereby hindering immune-elimination of CSCs during tumor initiation. Furthermore, unlike non-stem cancer cells (NSCCs), CSCs escaped doxorubicin-induced apoptosis, thus constituting major surviving population after three rounds of chemotherapy. These drug-survived CSCs were also able to generate CD4+CD25+FOXP3+ Treg cells. Our search for the underlying mechanism further unveiled the role of CSC-shed immune-suppressive cytokine TGFβ, which was further increased by chemotherapy, in generating tumor Treg cells. In conclusion, during initiation as well as after chemotherapy, when NSCCs are not present in the tumor microenvironment, CSCs, albeit present in low numbers, generate immunosuppressive CD4+CD25+FOXP3+ Treg cells in a contact-independent manner by shedding high levels of immune-suppressive Treg-polarizing cytokine TGFβ, thus escaping immune-elimination and initiating the tumor or causing tumor relapse.

Progress on the pathological tissue microenvironment barrier-modulated nanomedicine

Imbalance in the tissue microenvironment is the main obstacle to drug delivery and distribution in the human body. Before penetrating the pathological tissue microenvironment to the target site, therapeutic agents are usually accompanied by three consumption steps: the first step is tissue physical barriers for prevention of their penetration, the second step is inactivation of them by biological molecules, and the third step is a cytoprotective mechanism for preventing them from functioning on specific subcellular organelles. However, recent studies in drug-hindering mainly focus on normal physiological rather than pathological microenvironment, and the repair of damaged physiological barriers is also rarely discussed. Actually, both the modulation of pathological barriers and the repair of damaged physiological barriers are essential in the disease treatment and the homeostasis maintenance. In this review, we present an overview describing the latest advances in the generality of these pathological barriers and barrier-modulated nanomedicine. Overall, this review holds considerable significance for guiding the design of nanomedicine to increase drug efficacy in the future.

Modeling the Role of Immune Cell Conversion in the Tumor-Immune Microenvironment

Tumors develop in a complex physical, biochemical, and cellular milieu, referred to as the tumor microenvironment. Of special interest is the set of immune cells that reciprocally interact with the tumor, the tumor-immune microenvironment (TIME). The diversity of cell types and cell-cell interactions in the TIME has led researchers to apply concepts from ecology to describe the dynamics. However, while tumor cells are known to induce immune cells to switch from anti-tumor to pro-tumor phenotypes, this type of ecological interaction has been largely overlooked. To address this gap in cancer modeling, we develop a minimal, ecological model of the TIME with immune cell conversion, to highlight this important interaction and explore its consequences. A key finding is that immune conversion increases the range of parameters supporting a co-existence phase in which the immune system and the tumor reach a stalemate. Our results suggest that further investigation of the consequences of immune cell conversion, using detailed, data-driven models, will be critical for greater understanding of TIME dynamics.

Targeting LSD1 in tumor immunotherapy: rationale, challenges and potential

Lysine-specific demethylase 1 (LSD1) is an enzyme that removes lysine methylation marks from nucleosome histone tails and plays an important role in cancer initiation, progression, metastasis, and recurrence. Recent research shows that LSD1 regulates tumor cells and immune cells through multiple upstream and downstream pathways, enabling tumor cells to adapt to the tumor microenvironment (TME). As a potential anti-tumor treatment strategy, immunotherapy has developed rapidly in the past few years. However, most patients have a low response rate to available immune checkpoint inhibitors (ICIs), including anti-PD-(L)1 therapy and CAR-T cell therapy, due to a broad array of immunosuppressive mechanisms. Notably, inhibition of LSD1 turns "cold tumors" into "hot tumors" and subsequently enhances tumor cell sensitivity to ICIs. This review focuses on recent advances in LSD1 and tumor immunity and discusses a potential therapeutic strategy for combining LSD1 inhibition with immunotherapy.

The role of regulatory T cells and follicular T helper cells in HBV infection

Hepatitis B has become one of the major global health threats, especially in developing countries and regions. Hepatitis B virus infection greatly increases the risk for liver diseases such as cirrhosis and cancer. However, treatment for hepatitis B is limited when considering the huge base of infected people. The immune response against hepatitis B is mediated mainly by CD8+ T cells, which are key to fighting invading viruses, while regulatory T cells prevent overreaction of the immune response process. Additionally, follicular T helper cells play a key role in B-cell activation, proliferation, differentiation, and formation of germinal centers. The pathogenic process of hepatitis B virus is generally the result of a disorder or dysfunction of the immune system. Therefore, we present in this review the critical functions and related biological processes of regulatory T cells and follicular T helper cells during HBV infection.

The Effect of Lung Resection for NSCLC on Circulating Immune Cells: A Pilot Study

This pilot study sought to evaluate the circulating levels of immune cells, particularly regulatory T-cell (Treg) subsets, before and after lung resection for non-small cell lung cancer. Twenty-five patients consented and had specimens collected. Initially, peripheral blood of 21 patients was collected for circulating immune cell studies. Two of these patients were excluded due to technical issues, leaving 19 patients for the analyses of circulating immune cells. Standard gating and high-dimensional unsupervised clustering flow cytometry analyses were performed. The blood, tumors and lymph nodes were analyzed via single-cell RNA and TCR sequencing for Treg analyses in a total of five patients (including four additional patients from the initial 21 patients). Standard gating flow cytometry revealed a transient increase in neutrophils immediately following surgery, with a variable neutrophil-lymphocyte ratio and a stable CD4-CD8 ratio. Unexpectedly, the total Treg and Treg subsets did not change with surgery with standard gating in short- or long-term follow-up. Similarly, unsupervised clustering of Tregs revealed a dominant cluster that was stable perioperatively and long-term. Two small FoxP3hi clusters slightly increased following surgery. In the longer-term follow-up, these small FoxP3hi Treg clusters were not identified, indicating that they were likely a response to surgery. Single-cell sequencing demonstrated six CD4+FoxP3+ clusters among the blood, tumors and lymph nodes. These clusters had a variable expression of FoxP3, and several were mainly, or only, present in tumor and lymph node tissue. As such, serial monitoring of circulating Tregs may be informative, but not completely reflective of the Tregs present in the tumor microenvironment.

Acidity-mediated induction of FoxP3+ regulatory T cells

Glucose limitation and increased lactic acid levels are consequences of the elevated glycolytic activity of tumor cells, and constitute a metabolic barrier for the function of tumor infiltrating effector immune cells. The immune-suppressive functions of regulatory T cells (Tregs) are unobstructed in lactic-acid rich environments. However, the impact of lactic acid on the induction of Tregs remains unknown. We observed increased TGFβ-mediated induction of Forkhead box P3⁺ (FoxP3⁺ ) cells in the presence of extracellular lactic acid, in a glycolysis-independent, acidity-dependent manner. These CD4⁺ FoxP3⁺ cells expressed Treg-associated markers, including increased expression of CD39, and were capable of exerting suppressive functions. Corroborating these results in vivo, we observed that neutralizing the tumor pH by systemic administration of sodium bicarbonate (NaBi) decreased Treg abundance. We conclude that acidity augments Treg induction and propose that therapeutic targeting of acidity in the tumor microenvironment (TME) might reduce Treg-mediated immune suppression within tumors.

Development of a TGFβ-IL-2/15 Switch Receptor for Use in Adoptive Cell Therapy

Therapy employing T cells modified with chimeric antigen receptors (CARs) is effective in hematological malignancies but not yet in solid cancers. CAR T cell activity in solid tumors is limited by immunosuppressive factors, including transforming growth factor β (TGFβ). Here, we describe the development of a switch receptor (SwR), in which the extracellular domains of the TGFβ receptor are fused to the intracellular domains from the IL-2/15 receptor. We evaluated the SwR in tandem with two variants of a CAR that we have developed against STEAP1, a protein highly expressed in prostate cancer. The SwR-CAR T cell activity was assessed against a panel of STEAP1^+/- prostate cancer cell lines with or without over-expression of TGFβ, or with added TGFβ, by use of flow cytometry cytokine and killing assays, Luminex cytokine profiling, cell counts, and flow cytometry phenotyping. The results showed that the SwR-CAR constructs improved the functionality of CAR T cells in TGFβ-rich environments, as measured by T cell proliferation and survival, cytokine response, and cytotoxicity. In assays with four repeated target-cell stimulations, the SwR-CAR T cells developed an activated effector memory phenotype with retained STEAP1-specific activity. In conclusion, the SwR confers CAR T cells with potent and durable in vitro functionality in TGFβ-rich environments. The SwR may be used as an add-on construct for CAR T cells or other forms of adoptive cell therapy.

Engineering chimeric antigen receptor T cells for solid tumour therapy

Cell-based immunotherapy, for example, chimeric antigen receptor T (CAR-T) cell immunotherapy, has revolutionized cancer treatment, particularly for blood cancers. However, factors such as insufficient T cell tracking, tumour heterogeneity, inhibitory tumour microenvironment (TME) and T cell exhaustion limit the broad application of CAR-based immunotherapy for solid tumours. In particular, the TME is a complex and evolving entity, which is composed of cells of different types (e.g., cancer cells, immune cells and stromal cells), vasculature, soluble factors and extracellular matrix (ECM), with each component playing a critical role in CAR-T immunotherapy. Thus, developing approaches to mitigate the inhibitory TME factors is critical for future success in applying CAR-T cells for solid tumour treatment. Accordingly, understanding the bilateral interaction of CAR-T cells with the TME is in pressing need to pave the way for more efficient therapeutics. In the following review, we will discuss TME-associated aspects with an emphasis on T cell trafficking, ECM barriers, abnormal vasculature, solid tumour heterogenicity and immune suppressive microenvironment. We will then summarize current engineering strategies to overcome the challenges posed by the TME-associated factors. Lastly, the future directions for engineering efficient CAR-T cells for solid tumour therapy will be discussed.

Therapy sculpts the complex interplay between cancer and the immune system during tumour evolution

Cancer development is an evolutionary process. A key selection pressure is exerted by therapy, one of the few players in cancer evolution that can be controlled. As such, an understanding of how treatment acts to sculpt the tumour and its microenvironment and how this influences a tumour's subsequent evolutionary trajectory is critical. In this review, we examine cancer evolution and intra-tumour heterogeneity in the context of therapy. We focus on how radiotherapy, chemotherapy and immunotherapy shape both tumour development and the environment in which tumours evolve and how resistance can develop or be selected for during treatment.

Leverage biomaterials to modulate immunity for type 1 diabetes

The pathogeny of type 1 diabetes (T1D) is mainly provoked by the β-cell loss due to the autoimmune attack. Critically, autoreactive T cells firsthand attack β-cell in islet, that results in the deficiency of insulin in bloodstream and ultimately leads to hyperglycemia. Hence, modulating immunity to conserve residual β-cell is a desirable way to treat new-onset T1D. However, systemic immunosuppression makes patients at risk of organ damage, infection, even cancers. Biomaterials can be leveraged to achieve targeted immunomodulation, which can reduce the toxic side effects of immunosuppressants. In this review, we discuss the recent advances in harness of biomaterials to immunomodulate immunity for T1D. We investigate nanotechnology in targeting delivery of immunosuppressant, biological macromolecule for β-cell specific autoreactive T cell regulation. We also explore the biomaterials for developing vaccines and facilitate immunosuppressive cells to restore immune tolerance in pancreas.

Small secretory proteins of immune cells can modulate gynecological cancers

Small secretory proteins of immune cells are mostly Cytokines, which include chemokines, interleukins, interferons, lymphokines and tumor necrosis factors but not hormones or growth factors. These secretory proteins are the molecular messengers and primarily involved in autocrine, paracrine and endocrine signaling as immunomodulating agents. Hence, these proteins actually regulate the cells of immune system to communicate with one another to produce a synchronized, robust, still self-regulated response to a specific antigen. Chemokines are smaller secreted proteins that control overall immune cell movement and location; these chemokines are divided into 4 subgroups, namely, CXC, CC, CX3C and C according to the position of 4 conserved cysteine residues. Complete characterization of cytokines and chemokines can exploit their vast signaling networks to develop cancer treatments. These secretory proteins like IL-6, IL-10, IL-12, TNFα, CCL2, CXCL4 & CXCL8 are predominantly expressed in most of the gynecological cancers, which directly stimulate immune effector cells and stromal cells at the tumor site and augment tumor cell recognition by cytotoxic T-cells. Hence; these secretory proteins are the major regulators, which can actually modulate all kinds of gynecological cancers. Furthermore, advancements in adoptive T-cell treatment have relied on the use of multiple cytokines/chemokines to establish a highly regulated environment for anti-tumor T cell growth. A number of in vitro studies as well as animal models and clinical subjects have also shown that cytokines/chemokines have broad antitumor activity, which has been translated into a number of cancer therapy approaches. This review will focus on the foremost cytokines & chemokines involved in the majority of the gynecological malignancies and discuss their basic biology as well as clinical applications.

Focus on organoids: cooperation and interconnection with extracellular vesicles - Is this the future of in vitro modeling?

Organoids are simplified in vitro model systems of organs that are used for modeling tissue development and disease, drug screening, cell therapy, and personalized medicine. Despite considerable success in the design of organoids, challenges remain in achieving real-life applications. Organoids serve as unique and organized groups of micro physiological systems that are capable of self-renewal and self-organization. Moreover, they exhibit similar organ functionality(ies) as that of tissue(s) of origin. Organoids can be designed from adult stem cells, induced pluripotent stem cells, or embryonic stem cells. They consist of most of the important cell types of the desired tissue/organ along with the topology and cell-cell interactions that are highly similar to those of an in vivo tissue/organ. Organoids have gained interest in human biomedical research, as they demonstrate high promise for use in basic, translational, and applied research. As in vitro models, organoids offer significant opportunities for reducing the reliance and use of experimental animals. In this review, we will provide an overview of organoids, as well as those intercellular communications mediated by extracellular vesicles (EVs), and discuss the importance of organoids in modeling a tumor immune microenvironment (TIME). Organoids can also be exploited to develop a better understanding of intercellular communications mediated by EVs. Also, organoids are useful in mimicking TIME, thereby offering a better-controlled environment for studying various associated biological processes and immune cell types involved in tumor immunity, such as T-cells, macrophages, dendritic cells, and myeloid-derived suppressor cells, among others.

Systemic CD4 Immunity and PD-L1/PD-1 Blockade Immunotherapy

PD-L1/PD-1 blockade immunotherapy has changed the therapeutic approaches for the treatment of many cancers. Nevertheless, the mechanisms underlying its efficacy or treatment failure are still unclear. Proficient systemic immunity seems to be a prerequisite for efficacy, as recently shown in patients and in mouse models. It is widely accepted that expansion of anti-tumor CD8 T cell populations is principally responsible for anti-tumor responses. In contrast, the role of CD4 T cells has been less studied. Here we review and discuss the evidence supporting the contribution of CD4 T cells to anti-tumor immunity, especially recent advances linking CD4 T cell subsets to efficacious PD-L1/PD-1 blockade immunotherapy. We also discuss the role of CD4 T cell memory subsets present in peripheral blood before the start of immunotherapies, and their utility as predictors of response.

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

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

OATD-02 Validates the Benefits of Pharmacological Inhibition of Arginase 1 and 2 in Cancer

Simple Summary

Arginase 1 and 2 are drivers of multiple immunosuppressive mechanisms and tumour-specific metabolic adaptations. Pharmacological inhibition of extracellular ARG1 has shown antitumour efficacy in various syngeneic tumour models, however, the importance of ARG2 as a therapeutic target has only been demonstrated by genetic deletion studies. This is the first study validating the benefits of pharmacological inhibition of ARG2 in cancer. Our work describes OATD-02 as a potent dual ARG1/ARG2 inhibitor with a cellular activity (necessary for targeting ARG2) exhibiting immunomodulatory and direct antitumour efficacy in animal models. Our results present OATD-02 as an attractive option for combination with other immunotherapeutics, such as PD-1/PD-L1 antibodies or IDO1 inhibitors, especially in the therapy of particularly resistant hypoxic tumours. The presented findings provided the rationale for planning first-in-human clinical trials for OATD-02 in cancer patients.

Abstract

Background: Arginases play essential roles in metabolic pathways, determining the fitness of both immune and tumour cells. Along with the previously validated role of ARG1 in cancer, the particular significance of ARG2 as a therapeutic target has emerged as its levels correlate with malignant phenotype and poor prognosis. These observations unveil arginases, and specifically ARG2, as well-validated and promising therapeutic targets. OATD-02, a new boronic acid derivative, is the only dual inhibitor, which can address the benefits of pharmacological inhibition of arginase 1 and 2 in cancer. Methods: The inhibitory activity of OATD-02 was determined using recombinant ARG1 and ARG2, as well as in a cellular system using primary hepatocytes and macrophages. In vivo antitumor activity was determined in syngeneic models of colorectal and kidney carcinomas (CT26 and Renca, respectively), as well as in an ARG2-dependent xenograft model of leukaemia (K562). Results: OATD-02 was shown to be a potent dual (ARG1/ARG2) arginase inhibitor with a cellular activity necessary for targeting ARG2. Compared to a reference inhibitor with predominant extracellular activity towards ARG1, we have shown improved and statistically significant antitumor efficacy in the CT26 model and an immunomodulatory effect reflected by Treg inhibition in the Renca model. Importantly, OATD-02 had a superior activity when combined with other immunotherapeutics. Finally, OATD-02 effectively inhibited the proliferation of human K562 leukemic cells both in vitro and in vivo. Conclusions: OATD-02 is a potent small-molecule arginase inhibitor with optimal drug-like properties, including PK/PD profile. Excellent activity against intracellular ARG2 significantly distinguishes OATD-02 from other arginase inhibitors. OATD-02 represents a very promising drug candidate for the combined treatment of tumours, and is the only pharmacological tool that can effectively address the benefits of ARG1/ARG2 inhibition. OATD-02 will enter clinical trials in cancer patients in 2022.

Evaluation of T-cell aging-related immune phenotypes in the context of biological aging and multimorbidity in the Health and Retirement Study

BACKGROUND

Cellular changes in adaptive immune system accompany the process of aging and contribute to an aging-related immune phenotype (ARIP) characterized by decrease in naïve T-cells (TN) and increase in memory T-cells (TM). A population-representative marker of ARIP and its associations with biological aging and age-related chronic conditions have not been studied previously.

METHODS

We developed two ARIP indicators based on well understood age-related changes in T cell distribution: TN/(TCM (Central Memory) + TEM (Effector Memory) + TEFF (Effector)) (referred as TN/TM) in CD4 + and CD8 + T-cells. We compared them with existing ARIP measures including CD4/CD8 ratio and CD8 + TN cells by evaluating associations with chronological age and the Klemera Doubal measure of biological age (measured in years) using linear regression, multimorbidity using multinomial logistic regression and two-year mortality using logistic regression.

RESULTS

CD8 + TN and CD8 + TN/TM had the strongest inverse association with chronological age (beta estimates: -3.41 and -3.61 respectively; p-value < 0.0001) after adjustment for sex, race/ethnicity and CMV status. CD4 + TN/TM and CD4 + TN had the strongest inverse association with biological age (β = -0.23; p = 0.003 and β = -0.24; p = 0.004 respectively) after adjustment for age, sex, race/ethnicity and CMV serostatus. CD4/CD8 ratio was not associated with chronological age or biological age. CD4 + TN/TM and CD4 + TN was inversely associated with multimorbidity. For CD4 + TN/TM, people with 2 chronic conditions had an odds ratio of for 0.74 (95%CI: 0.63-0.86 p = 0.0003) compared to those without any chronic conditions while those with 3 chronic conditions had an odds ratio of 0.75 (95% CI: 0.63-0.90; p = 0.003) after adjustment for age, sex, race/ethnicity, CMV serostatus, smoking, and BMI. The results for the CD4 + TN subset were very similar to the associations seen with the CD4 + TN/TM. CD4 + TN/TM and CD4 + TN were both associated with two-year mortality (OR = 0.80 (95% CI: 0.67-0.95; p = 0.01) and 0.81 (0.70-0.94; p = 0.01), respectively).

CONCLUSION

CD4 + TN/TM and CD4 + TN had a stronger association with biological age, age-related morbidity and mortality compared to other ARIP measures. Future longitudinal studies are needed to evaluate the utility of the CD4 + subsets in predicting the risk of aging-related outcomes.

Colorectal Cancer-Infiltrating Regulatory T Cells: Functional Heterogeneity, Metabolic Adaptation, and Therapeutic Targeting

Colorectal cancer (CRC) is a heterogeneous disease with one of the highest rates of incidence and mortality among cancers worldwide. Understanding the CRC tumor microenvironment (TME) is essential to improve diagnosis and treatment. Within the CRC TME, tumor-infiltrating lymphocytes (TILs) consist of a heterogeneous mixture of adaptive immune cells composed of mainly anti-tumor effector T cells (CD4+ and CD8+ subpopulations), and suppressive regulatory CD4+ T (Treg) cells. The balance between these two populations is critical in anti-tumor immunity. In general, while tumor antigen-specific T cell responses are observed, tumor clearance frequently does not occur. Treg cells are considered to play an important role in tumor immune escape by hampering effective anti-tumor immune responses. Therefore, CRC-tumors with increased numbers of Treg cells have been associated with promoting tumor development, immunotherapy failure, and a poorer prognosis. Enrichment of Treg cells in CRC can have multiple causes including their differentiation, recruitment, and preferential transcriptional and metabolic adaptation to the TME. Targeting tumor-associated Treg cell may be an effective addition to current immunotherapy approaches. Strategies for depleting Treg cells, such as low-dose cyclophosphamide treatment, or targeting one or more checkpoint receptors such as CTLA-4 with PD-1 with monoclonal antibodies, have been explored. These have resulted in activation of anti-tumor immune responses in CRC-patients. Overall, it seems likely that CRC-associated Treg cells play an important role in determining the success of such therapeutic approaches. Here, we review our understanding of the role of Treg cells in CRC, the possible mechanisms that support their homeostasis in the tumor microenvironment, and current approaches for manipulating Treg cells function in cancer.

Global Stability and Thermal Optimal Control Strategies for Hyperthermia Treatment of Malignant Tumors

Malignant tumor (cancer) is the leading cause of death globally and the annual cost of managing cancer is trillions of dollars. Although, there are established therapies including radiotherapy, chemotherapy and phototherapy for malignant tumors, the hypoxic environment of tumors and poor perfusion act as barriers to these therapies. Hyperthermia takes advantage of oxygen deficiency and irregular perfusion in the tumor environment to destroy malignant cells. Despite successes recorded with hyperthermia, there are concerns with the post-treatment condition of patients as well as the required thermal dose to prevent harm. The investigation of the dynamics of tumor-induced immune suppression with hyperthermia treatment using mathematical analysis and optimal control theory is potentially valuable in the development of hyperthermia treatment. The role of novel tumor-derived cytokines in counterattacking immune cells is considered in this study as a mechanism accounting for the aggressiveness of malignant tumors. Since biological processes are not instantaneous, a discrete time delay is used to model biological processes involved in tumor inhibitory mechanisms by secretion, the elaboration of suppressive cells, and effector cell differentiation to produce suppressive cells. Analytical results obtained using Lyapunov’s function indicate the conditions required for global stability of the tumor-present steady-state. A thermal optimal control strategy is pursued based on optimal control theory, and the best strategy to avoid adverse outcomes is obtained. We validate the analytical results numerically and demonstrate the impact of both inadequate and excessive heat on the dynamics of interactive cell functioning.

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

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

Pregnancy and Tumour: The Parallels and Differences in Regulatory T Cells

Immunological tolerance plays a critical role during pregnancy as semi-allogeneic fetus must be protected from immune responses during the gestational period. Regulatory T cells (Tregs), a subpopulation of CD4+ T cells that express transcription factor Foxp3, are central to the maintenance of immunological tolerance and prevention of autoimmunity. Tregs are also known to accumulate at placenta in uterus during pregnancy, and they confer immunological tolerance at maternal-fetal interface by controlling the immune responses against alloantigens. Thus, uterine Tregs help in maintaining an environment conducive for survival of the fetus during gestation, and low frequency or dysfunction of Tregs is associated with recurrent spontaneous abortions and other pregnancy-related complications such as preeclampsia. Interestingly, there are many parallels in the development of placenta and solid tumours, and the tumour microenvironment is considered to be somewhat similar to that at maternal-fetal interface. Moreover, Tregs play a largely similar role in tumour immunity as they do at placenta- they create a tolerogenic system and suppress the immune responses against the cells within tumour and at maternal-fetal interface. In this review, we discuss the role of Tregs in supporting the proper growth of the embryo during pregnancy. We also highlight the similarities and differences between Tregs at maternal-fetal interface and tumour Tregs, in an attempt to draw a comparison between their roles in these two physiologic and pathologic states.

Hallmarks of Resistance to Immune-Checkpoint Inhibitors

Immune-checkpoint inhibitors (ICI), although revolutionary in improving long-term survival outcomes, are mostly effective in patients with immune-responsive tumors. Most patients with cancer either do not respond to ICIs at all or experience disease progression after an initial period of response. Treatment resistance to ICIs remains a major challenge and defines the biggest unmet medical need in oncology worldwide. In a collaborative workshop, thought leaders from academic, biopharma, and nonprofit sectors convened to outline a resistance framework to support and guide future immune-resistance research. Here, we explore the initial part of our effort by collating seminal discoveries through the lens of known biological processes. We highlight eight biological processes and refer to them as immune resistance nodes. We examine the seminal discoveries that define each immune resistance node and pose critical questions, which, if answered, would greatly expand our notion of immune resistance. Ultimately, the expansion and application of this work calls for the integration of multiomic high-dimensional analyses from patient-level data to produce a map of resistance phenotypes that can be utilized to guide effective drug development and improved patient outcomes.

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

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

Dual Effect of Immune Cells within Tumour Microenvironment: Pro- and Anti-Tumour Effects and Their Triggers

Our body is constantly exposed to pathogens or external threats, but with the immune response that our body can develop, we can fight off and defeat possible attacks or infections. Nevertheless, sometimes this threat comes from an internal factor. Situations such as the existence of a tumour also cause our immune system (IS) to be put on alert. Indeed, the link between immunology and cancer is evident these days, with IS being used as one of the important targets for treating cancer. Our IS is able to eliminate those abnormal or damaged cells found in our body, preventing the uncontrolled proliferation of tumour cells that can lead to cancer. However, in several cases, tumour cells can escape from the IS. It has been observed that immune cells, the extracellular matrix, blood vessels, fat cells and various molecules could support tumour growth and development. Thus, the developing tumour receives structural support, irrigation and energy, among other resources, making its survival and progression possible. All these components that accompany and help the tumour to survive and to grow are called the tumour microenvironment (TME). Given the importance of its presence in the tumour development process, this review will focus on one of the components of the TME: immune cells. Immune cells can support anti-tumour immune response protecting us against tumour cells; nevertheless, they can also behave as pro-tumoural cells, thus promoting tumour progression and survival. In this review, the anti-tumour and pro-tumour immunity of several immune cells will be discussed. In addition, the TME influence on this dual effect will be also analysed.

Inhibition of TGF-β Signaling Attenuates Disuse-induced Trabecular Bone Loss After Spinal Cord Injury in Male Mice

Bone loss is one of the most common complications of immobilization after spinal cord injury (SCI). Whether transforming growth factor (TGF)-β signaling plays a role in SCI-induced disuse bone loss has not been determined. Thus, 16-week-old male mice underwent sham or spinal cord contusion injury to cause complete hindlimb paralysis. Five days later, 10 mg/kg/day control (IgG) or anti-TGF-β1,2,3 neutralizing antibody (1D11) was administered twice weekly for 4 weeks. Femurs were examined by micro-computed tomography (micro-CT) scanning and histology. Bone marrow (BM) supernatants were analyzed by enzyme-linked immunosorbent assay for levels of procollagen type 1 intact N-terminal propeptide (P1NP), tartrate-resistant acid phosphatase (TRAcP-5b), receptor activator of nuclear factor-kappa B ligand (RANKL), osteoprotegerin (OPG), and prostaglandin E2 (PGE2). Distal femoral micro-CT analysis showed that SCI-1D11 mice had significantly (P < .05) attenuated loss of trabecular fractional bone volume (123% SCI-1D11 vs 69% SCI-IgG), thickness (98% vs 81%), and connectivity (112% vs 69%) and improved the structure model index (2.1 vs 2.7). Histomorphometry analysis revealed that osteoclast numbers were lower in the SCI-IgG mice than in sham-IgG control. Biochemically, SCI-IgG mice had higher levels of P1NP and PGE2 but similar TRAcP-5b and RANKL/OPG ratio to the sham-IgG group. The SCI-1D11 group exhibited higher levels of P1NP but similar TRAcP-5b, RANKL/OPG ratio, and PGE2 to the sham-1D11 group. Furthermore, 1D11 treatment prevented SCI-induced hyperphosphorylation of tau protein in osteocytes, an event that destabilizes the cytoskeleton. Together, inhibition of TGF-β signaling after SCI protects trabecular bone integrity, likely by balancing bone remodeling, inhibiting PGE2 elevation, and preserving the osteocyte cytoskeleton.

TGFβ Signaling in the Pancreatic Tumor Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is associated with poor clinical outcomes, largely attributed to incomplete responses to standard therapeutic approaches. Recently, selective inhibitors of the Transforming Growth Factor β (TGFβ) signaling pathway have shown early promise in the treatment of PDAC, particularly as a means of augmenting responses to chemo- and immunotherapies. However, TGFβ is a potent and pleiotropic cytokine with several seemingly paradoxical roles within the pancreatic tumor microenvironment (TME). Although TGFβ signaling can have potent tumor-suppressive effects in epithelial cells, TGFβ signaling also accelerates pancreatic tumorigenesis by enhancing epithelial-to-mesenchymal transition (EMT), fibrosis, and the evasion of the cytotoxic immune surveillance program. Here, we discuss the known roles of TGFβ signaling in pancreatic carcinogenesis, the biologic consequences of the genetic inactivation of select components of the TGFβ pathway, as well as past and present attempts to advance TGFβ inhibitors in the treatment of PDAC patients.

Genetical engineering for NK and T cell immunotherapy with CRISPR/Cas9 technology: Implications and challenges

Immunotherapy has become one of the most promising strategies in cancer therapies. Among the therapeutic alternatives, genetically engineered NK/T cell therapies have emerged as powerful and innovative therapeutic modalities for cancer patients with precise targeting and impressive efficacy. Nonetheless, this approach still faces multiple challenges, such as immunosuppressive tumor microenvironment, exhaustion of immune effector cells in tumors, off-target effects manufacturing complexity, and poor infiltration of effector cells, all of which need to be overcome for further utilization to cancers. Recently, CRISPR/Cas9 genome editing technology, with the goal of enhancing the efficacy and increasing the availability of engineered effector cell therapies, has shown considerable potential in the novel strategies and options to overcome these limitations. Here we review the current progress of the applications of CRISPR in cancer immunotherapy. Furthermore, we discuss issues related to the NK/T cell applications, gene delivery methods, efficiency, challenges, and implications of CRISPR/Cas9.

Curcumin as an Adjuvant to Cancer Immunotherapy

The components of the immune system play a very sincere and crucial role in combating tumors. However, despite their firm efforts of elimination, tumor cells cleverly escape the surveillance process by adopting several immune evasion mechanisms. The conversion of immunogenicity of tumor microenvironment into tolerogenic is considered as a prime reason for tumor immune escape. Therapeutically, different immunotherapies have been adopted to block such immune escaping routes along with better clinical outcomes. Still, the therapies are haunted by several drawbacks. Over time, curcumin has been considered as a potential anti-cancer molecule. Its potentialities have been recorded against the standard hallmarks of cancer such as continuous proliferation, escaping apoptosis, continuous angiogenesis, insensitivity to growth inhibitors, tissue invasion, and metastasis. Hence, the diversity of curcumin functioning has already been established and exploration of its application with immunotherapies might open up a new avenue for scientists and clinicians. In this review, we briefly discuss the tumor's way of immune escaping, followed by various modern immunotherapies that have been used to encounter the escaping paths and their minute flaws. Finally, the conclusion has been drawn with the application of curcumin as a potential immune-adjuvant, which fearlessly could be used with immunotherapies for best outcomes.

Applications and explorations of CRISPR/Cas9 in CAR T-cell therapy

Chimeric antigen receptor(CAR) T-cell therapy has shown remarkable effects and promising prospects in patients with refractory or relapsed malignancies, pending further progress in the next-generation CAR T cells with more optimized structure, enhanced efficacy and reduced toxicities. The clustered regulatory interspaced short palindromic repeat/CRISPR-associated protein 9 (CRISPR/Cas9) technology holds immense promise for advancing the field owing to its flexibility, simplicity, high efficiency and multiplexing in precise genome editing. Herein, we review the applications and explorations of CRISPR/Cas9 technology in constructing allogenic universal CAR T cells, disrupting inhibitory signaling to enhance potency and exploration of safer and more controllable novel CAR T cells.

Regulatory T-Cells as an Emerging Barrier to Immune Checkpoint Inhibition in Lung Cancer

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment paradigm for lung cancer in recent years. These strategies consist of neutralizing antibodies against negative regulators of immune function, most notably cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), programmed cell death protein 1 (PD-1), and PD-1 ligand 1 (PD-L1), thereby impeding the ability of tumor cells to escape immune surveillance. Though ICIs have proven a significant advance in lung cancer therapy, overall survival rates remain low, and lung cancer continues to be the leading cause of cancer-related death in the United States. It is therefore imperative to better understand the barriers to the efficacy of ICIs, particularly additional mechanisms of immunosuppression within the lung cancer microenvironment. Recent evidence suggests that regulatory T-lymphocytes (Tregs) serve as a central mediator of immune function in lung cancer, suppressing sterilizing immunity and contributing to the clinical failure of ICIs. Here, we provide a comprehensive summary of the roles of Tregs in lung cancer pathobiology and therapy, as well as the potential means through which these immunosuppressive mechanisms can be overcome.

Role of Microenvironment in Non-Hodgkin Lymphoma: Understanding the Composition and Biology

Lymphoma microenvironment is a dynamic and well-orchestrated network of various immune and stromal cells that is indispensable for tumor cell survival, growth, migration, immune escape, and drug resistance. Recent progress has enhanced our knowledge of the pivotal role of microenvironment in lymphomagenesis. Understanding the characteristics, functions, and contributions of various components of the tumor niche, along with its bidirectional interactions with tumor cells, is paramount. It offers the potential to identify new therapeutic targets with the ability to restore antitumor immune surveillance and eliminate the protumoral factors contributed by the tumor niche.

Standing Variations Modeling Captures Inter-Individual Heterogeneity in a Deterministic Model of Prostate Cancer Response to Combination Therapy

Sipuleucel-T (Provenge) is the first live cell vaccine approved for advanced, hormonally refractive prostate cancer. However, survival benefit is modest and the optimal combination or schedule of sipuleucel-T with androgen depletion remains unknown. We employ a nonlinear dynamical systems approach to modeling the response of hormonally refractive prostate cancer to sipuleucel-T. Our mechanistic model incorporates the immune response to the cancer elicited by vaccination, and the effect of androgen depletion therapy. Because only a fraction of patients benefit from sipuleucel-T treatment, inter-individual heterogeneity is clearly crucial. Therefore, we introduce our novel approach, Standing Variations Modeling, which exploits inestimability of model parameters to capture heterogeneity in a deterministic model. We use data from mouse xenograft experiments to infer distributions on parameters critical to tumor growth and to the resultant immune response. Sampling model parameters from these distributions allows us to represent heterogeneity, both at the level of the tumor cells and the individual (mouse) being treated. Our model simulations explain the limited success of sipuleucel-T observed in practice, and predict an optimal combination regime that maximizes predicted efficacy. This approach will generalize to a range of emerging cancer immunotherapies.

Simultaneous Inhibition of LSD1 and TGFβ Enables Eradication of Poorly Immunogenic Tumors with Anti-PD-1 Treatment

Epigenetic regulators are a class of promising targets in combination with immune checkpoint inhibitors for cancer treatment, but the impact of the broad effects of perturbing epigenetic regulators on tumor immunotherapy remains to be fully explored. Here we show that ablation of the histone demethylase LSD1 in multiple tumor cells induces TGFβ expression, which exerts an inhibitory effect on T-cell immunity through suppressing the cytotoxicity of intratumoral CD8⁺ T cells and consequently dampens the antitumor effect of LSD1 ablation-induced T-cell infiltration. Importantly, concurrent depletion of LSD1 and TGFβ in combination with PD-1 blockade significantly increases both CD8⁺ T-cell infiltration and cytotoxicity, leading to eradication of poorly immunogenic tumors and a long-term protection from tumor rechallenge. Thus, combining LSD1 inhibition with blockade of TGFβ and PD-1 may represent a promising triple combination therapy for treating certain refractory tumors. SIGNIFICANCE: Cotargeting LSD1 and TGFβ cooperatively elevates intratumoral CD8⁺ T-cell infiltration and unleashes their cytotoxicity, leading to tumor eradication upon anti-PD-1 treatment. Our findings illustrate a duality of epigenetic perturbations in immunotherapy and implicate the combination of LSD1 inhibition with dual PD-1/TGFβ blockade in treating certain poorly immunogenic tumors.This article is highlighted in the In This Issue feature, p. 1861.

Tgf-β1 produced by activated CD4(+) T Cells Antagonizes T Cell Surveillance of Tumor Development

TGFβ1 is a regulatory cytokine with a crucial function in the control of T cell tolerance to tumors. Our recent study revealed that T cell-produced TGFβ1 is essential for inhibiting cytotoxic T cell responses to tumors. However, the exact TGFβ1-producing T cell subset required for tumor immune evasion remains unknown. Here we showed that deletion of TGFβ1 from CD8⁺ T cells or Foxp3⁺ regulatory T (Treg) cells did not protect mice against transplanted tumors. However, absence of TGFβ1 produced by activated CD4⁺ T cells and Treg cells inhibited tumor growth, and protected mice from spontaneous prostate cancer. These findings suggest that TGFβ1 produced by activated CD4⁺ T cells is a necessary requirement for tumor evasion from immunosurveillance.

Tumour-directed microenvironment remodelling at a glance

The tissue microenvironment supports normal tissue function and regulates the behaviour of parenchymal cells. Tumour cell behaviour, on the other hand, diverges significantly from that of their normal counterparts, rendering the microenvironment hostile to tumour cells. To overcome this problem, tumours can co-opt and remodel the microenvironment to facilitate their growth and spread. This involves modifying both the biochemistry and the biophysics of the normal microenvironment to produce a tumour microenvironment. In this Cell Science at a Glance article and accompanying poster, we outline the key processes by which epithelial tumours influence the establishment of the tumour microenvironment. As the microenvironment is populated by genetically normal cells, we discuss how controlling the microenvironment is both a significant challenge and a key vulnerability for tumours. Finally, we review how new insights into tumour-microenvironment interactions has led to the current consensus on how these processes may be targeted as novel anti-cancer therapies.

Distribution of Regulatory T-Cells and Other Phenotypes of T-Cells in Tumors and Regional Lymph Nodes of Colorectal Cancer Patients

BACKGROUND/AIM

Tumor microenvironments consist of many types of immune cells, in which regulatory T-cells (Tregs) are supposed to play important roles to suppress anti-tumor immunity. Regional lymph nodes are essential for antitumor immunity in colorectal cancer (CRC). In this study, we compared the diversity of phenotypes of T-cells in normal tissue and regional lymph nodes in order to determine the immunosuppressive mechanism of lymph node metastasis of CRC.

PATIENTS AND METHODS

Fifty patients were enrolled in this study, and paired samples (tumor tissue, normal tissue, and three regional lymph node samples and as well as non-regional lymph node samples) were obtained from each patient. In each paired-sample set, the proportions of different immune cell types and T-cells expressing immune checkpoint molecules were compared using flow cytometry.

RESULTS

Higher proportions of Tregs [7.58% (4.94%-13.87%) vs. 1.79% (0.03%-5.36%), p<0.001] and lower proportions of INFγ-producing CD4-positive T (iCD4+) cells [21.49% (12.08%-27.35%) vs. 26.55% (15.65%-37.63%), p<0.001] were observed in tumor tissue than in normal mucosa. Parts of regional lymph nodes nearest the tumor had a greater proportion of Tregs [5.86% (4.18%-7.69%)] and lower proportions of iCD4+ [5.94% (3.51%-9.04%)] and INFγ-producing CD8-positive T (iCD8+) cells [21.93% (14.92%-35.90%)] than distant parts of regional lymph nodes and non-regional lymph nodes. Both immune-suppressing molecules (CTLA-4 and PD-1) and immune-promoting molecules (OX-40 and ICOS) tended to be highly expressed in tumor tissue and local lymph nodes.

CONCLUSION

In patients with CRC, regional lymph nodes, especially the parts nearest the tumor, had a higher proportion of Tregs and other suppressive immunophenotypes of T-cells than those located more distantly.

Systemic CD4 Immunity as a Key Contributor to PD-L1/PD-1 Blockade Immunotherapy Efficacy

PD-L1/PD-1 blockade immunotherapy has significantly improved treatment outcome for several cancer types compared to conventional cytotoxic therapies. However, the specific molecular and cellular mechanisms behind its efficacy are currently unclear. There is increasing evidence in murine models and in patients that unveil the key importance of systemic immunity to achieve clinical responses under several types of immunotherapy. Indeed, PD-L1/PD-1 blockade induces the expansion of systemic CD8+ PD-1+ T cell subpopulations which might be responsible for direct anti-tumor responses. However, the role of CD4+ T cells in PD-L1/PD-1 blockade-induced anti-tumor responses has been less documented. In this review we focus on the experimental data supporting the “often suspected” indispensable helper function of CD4 T cells towards CD8 effector anti-tumor responses in cancer; and particularly, we highlight the recently published studies uncovering the key contribution of systemic CD4 T cells to clinical efficacy in PD-L1/PD-1 blockade therapies. We conclude and propose that the presence of specific CD4 T cell memory subsets in peripheral blood before the initiation of treatments is a strong predictor of responses in non-small cell lung cancer patients. Therefore, development of new approaches to improve CD4 responses before PD-L1/PD-1 blockade therapy could be the solution to increase response rates and survival of patients.

Immunometabolism of regulatory T cells in cancer

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

TGF-β2 is a Prognostic Biomarker Correlated with Immune Cell Infiltration in Colorectal Cancer: A STROBE-compliant article

Transforming growth factor-beta (TGF-β2) is an important cytokine regulating immune cell function. However, whether TGF-β2 controls the invasion of colorectal cancer (CRC) by immune cells is unknown. Therefore, we evaluated the expression of TGF-β2 using multiple databases and determined the relationship between TGF-β2 expression and tumor immune infiltration defined by a set of genetic markers. The analysis demonstrated that the expression of TGF-β2 is closely related to the outcome of many cancers, and this correlation was particularly strong in CRC. In addition, the increased expression of TGF-β2 was significantly associated with the expression of various markers of specific immune cell subpopulations, and overexpression of TGF-β2 was closely related to the prognosis of colon cancer patients. Moreover, TGF-β2 was related to the prognosis and infiltration of the tumor by immune cells in CRC patients. The obtained results indicate that TGF-β2 is a critical factor regulating the recruitment of immune cells and controls their infiltration into colorectal tumors. Thus, high expression of TGF-β2 not only facilitates the prognosis in CRC patients, but also may provide a new target for the treatment of CRC.

Cancer stem cell secretome in the tumor microenvironment: a key point for an effective personalized cancer treatment

Cancer stem cells (CSCs) represent a tumor subpopulation responsible for tumor metastasis and resistance to chemo- and radiotherapy, ultimately leading to tumor relapse. As a consequence, the detection and eradication of this cell subpopulation represent a current challenge in oncology medicine. CSC phenotype is dependent on the tumor microenvironment (TME), which involves stem and differentiated tumor cells, as well as different cell types, such as mesenchymal stem cells, endothelial cells, fibroblasts and cells of the immune system, in addition to the extracellular matrix (ECM), different in composition to the ECM in healthy tissues. CSCs regulate multiple cancer hallmarks through the interaction with cells and ECM in their environment by secreting extracellular vesicles including exosomes, and soluble factors such as interleukins, cytokines, growth factors and other metabolites to the TME. Through these factors, CSCs generate and activate their own tumor niche by recruiting stromal cells and modulate angiogenesis, metastasis, resistance to antitumor treatments and their own maintenance by the secretion of different factors such as IL-6, VEGF and TGF-ß. Due to the strong influence of the CSC secretome on disease development, the new antitumor therapies focus on targeting these communication networks to eradicate the tumor and prevent metastasis, tumor relapse and drug resistance. This review summarizes for the first time the main components of the CSC secretome and how they mediate different tumor processes. Lastly, the relevance of the CSC secretome in the development of more precise and personalized antitumor therapies is discussed.

The influences of TGF-β1 upon the human adenocarcinoma cell of lung A549 and cellular immunity

Background

The cellular immunity of lung cancer patients is mainly the immune response of T cells, which plays an important role in tumour cell killing and immune surveillance. Transforming growth factor 1 (TGF-β1) is secreted by tumour cells that can suppress the immune response and is an important group of immune down-regulation factors. Our study aims to investigate the effect of TGF-β1 on the morphology and cellular immune function of A549 and peripheral blood mononuclear cells (PBMCs).

Methods

A549 cell line was cultured, PBMCs were cultured with different concentrations of TGF-β1, and the morphology of A549 cells and PBMCs were seen. The levels of interleukin (IL)-2, IL-4, IL-6, IL-10, IFN-γ, and TNF and the numbers of CD3, CD4, CD8, CD4/CD8, and CD3 CD25 and CD4 CD25 in PBMCs were detected.

Results

During co-culture of A549 with PBMCs, TGF-β1 can induced A549 showing epithelial-to-mesenchymal transition, enhanced its ability of migration and infiltration. Simultaneously, TGF-β1 can depressing the growth and proliferation of PBMCs, inhibiting T-cell activation, and accelerating the PBMCs apoptosis. TGF-β1 can inhibits A549 Th1 related-cytokines, enhance Th2 related-cytokines, cause the disorder of Th1/Th2, resulting in the Th1 cellular dominate immunity decline.

Conclusions

TGF-β1 may affect the secretion of related cytokines, hinder the activation of T lymphocytes, destroy the immune surveillance and killing effect of the body, and thus inhibit the cellular immunity.

Implications of immune-mediated metastatic growth on metastatic dormancy, blow-up, early detection, and treatment

Metastatic seeding of distant organs can occur in the very early stages of primary tumor development. Once seeded, these micrometastases may enter a dormant phase that can last decades. Curiously, the surgical removal of the primary tumor can stimulate the accelerated growth of distant metastases, a phenomenon known as metastatic blow-up. Recent clinical evidence has shown that the immune response can have strong tumor promoting effects. In this work, we investigate if the pro-tumor effects of the immune response can have a significant contribution to metastatic dormancy and metastatic blow-up. We develop an ordinary differential equation model of the immune-mediated theory of metastasis. We include both anti- and pro-tumor immune effects, in addition to the experimentally observed phenomenon of tumor-induced immune cell phenotypic plasticity. Using geometric singular perturbation analysis, we derive a rather simple model that captures the main processes and, at the same time, can be fully analyzed. Literature-derived parameter estimates are obtained, and model robustness is demonstrated through a time dependent sensitivity analysis. We determine conditions under which the parameterized model can successfully explain both metastatic dormancy and blow-up. The results confirm the significant active role of the immune system in the metastatic process. Numerical simulations suggest a novel measure to predict the occurrence of future metastatic blow-up in addition to new potential avenues for treatment of clinically undetectable micrometastases.