TGF-beta inhibits IL-2 production and promotes cell cycle arrest in TCR-activated effector/memory T cells in the presence of sustained TCR signal transduction

Development of pharmacological immunoregulatory anti-cancer therapeutics: current mechanistic studies and clinical opportunities

Immunotherapy represented by anti-PD-(L)1 and anti-CTLA-4 inhibitors has revolutionized cancer treatment, but challenges related to resistance and toxicity still remain. Due to the advancement of immuno-oncology, an increasing number of novel immunoregulatory targets and mechanisms are being revealed, with relevant therapies promising to improve clinical immunotherapy in the foreseeable future. Therefore, comprehending the larger picture is important. In this review, we analyze and summarize the current landscape of preclinical and translational mechanistic research, drug development, and clinical trials that brought about next-generation pharmacological immunoregulatory anti-cancer agents and drug candidates beyond classical immune checkpoint inhibitors. Along with further clarification of cancer immunobiology and advances in antibody engineering, agents targeting additional inhibitory immune checkpoints, including LAG-3, TIM-3, TIGIT, CD47, and B7 family members are becoming an important part of cancer immunotherapy research and discovery, as are structurally and functionally optimized novel anti-PD-(L)1 and anti-CTLA-4 agents and agonists of co-stimulatory molecules of T cells. Exemplified by bispecific T cell engagers, newly emerging bi-specific and multi-specific antibodies targeting immunoregulatory molecules can provide considerable clinical benefits. Next-generation agents also include immune epigenetic drugs and cytokine-based therapeutics. Cell therapies, cancer vaccines, and oncolytic viruses are not covered in this review. This comprehensive review might aid in further development and the fastest possible clinical adoption of effective immuno-oncology modalities for the benefit of patients.

Induction of a memory-like CD4+ T-cell phenotype by airway smooth muscle cells

In asthma, CD4+ T-cell interaction with airway smooth muscle (ASM) may enhance its contractile properties and promote its proliferation. However, less is known about the effects of this interaction on T cells. To explore the consequences of interaction of CD4+ T cells with ASM we placed the cells in co-culture and analyzed the phenotypic and functional changes in the T cells. Effector status as well as cytokine expression was assessed by flow cytometry. An increase in CD45RA-CD45RO+ memory T cells was observed after co-culture; however, these cells were not more responsive to CD3/28 restimulation. A reduction in mitochondrial coupling and an increase in the production of mitochondrial reactive oxygen species by CD4+ T cells post-restimulation suggested altered mitochondrial metabolism after co-culture. RNA sequencing analysis of the T cells revealed characteristic downregulation of effector T-cell-associated genes, but a lack of upregulation of memory T-cell-associated genes. The results of this study demonstrate that ASM cells can induce a phenotypic shift in CD4+ T cells into memory-like T cells but with reduced capacity for activation.

TGF-β blockade drives a transitional effector phenotype in T cells reversing SIV latency and decreasing SIV reservoirs in vivo

HIV-1 persistence during ART is due to the establishment of long-lived viral reservoirs in resting immune cells. Using an NHP model of barcoded SIVmac239 intravenous infection and therapeutic dosing of anti-TGFBR1 inhibitor galunisertib (LY2157299), we confirm the latency reversal properties of in vivo TGF-β blockade, decrease viral reservoirs and stimulate immune responses. Treatment of eight female, SIV-infected macaques on ART with four 2-weeks cycles of galunisertib leads to viral reactivation as indicated by plasma viral load and immunoPET/CT with a 64Cu-DOTA-F(ab')2-p7D3-probe. Post-galunisertib, lymph nodes, gut and PBMC exhibit lower cell-associated (CA-)SIV DNA and lower intact pro-virus (PBMC). Galunisertib does not lead to systemic increase in inflammatory cytokines. High-dimensional cytometry, bulk, and single-cell (sc)RNAseq reveal a galunisertib-driven shift toward an effector phenotype in T and NK cells characterized by a progressive downregulation in TCF1. In summary, we demonstrate that galunisertib, a clinical stage TGF-β inhibitor, reverses SIV latency and decreases SIV reservoirs by driving T cells toward an effector phenotype, enhancing immune responses in vivo in absence of toxicity.

A novel GPI-anchored dominant-negative TGF-β receptor II renders T cells unresponsive to TGF-β signaling

Transforming growth factor β (TGF-β) is a pleiotropic cytokine expressed by a wide range of cell types and is known for hampering the effectiveness of cancer immune cell therapeutic approaches. We have designed a novel construct containing the extracellular domain of the TGF-β receptor II linked to a glycosylphosphatidylinositol (GPI) anchor (GPI-ecto-TβRII) lacking the transmembrane and cytoplasmic signaling domain of TGF-β receptor II (TβRII). T cells transduced with lentivirus expressing the GPI-ecto-TβRII construct show 5 to 15 times higher membrane expression compared with a previously established dominant-negative receptor carrying a truncated signaling domain. GPI-ecto-TβRII expression renders T cells unresponsive to TGF-β-induced signaling seen by a lack of SMAD phosphorylation upon exogeneous TGF-β treatment. Transduced T cells continue to express high levels of IFNγ and granulocyte-macrophage colony-stimulating factor (GM-CSF), among other cytokines, in the presence of TGF-β while cytokine expression in untransduced T cells is being markedly suppressed. Furthermore, T cells expressing GPI-ecto-TβRII constructs have been shown to efficiently capture and inactivate TGF-β from their environment. These results indicate the potential benefits of GPI-ecto-TβRII expressing cytotoxic T cells (CTLs) in future cell therapies.

TGF-β blockade drives a transitional effector phenotype in T cells reversing SIV latency and decreasing SIV reservoirs in vivo

HIV-1 persistence during ART is due to the establishment of long-lived viral reservoirs in resting immune cells. Using an NHP model of barcoded SIVmac239 intravenous infection and therapeutic dosing of the anti-TGFBR1 inhibitor galunisertib (LY2157299), we confirmed the latency reversal properties of in vivo TGF-β blockade, decreased viral reservoirs and stimulated immune responses. Eight SIV-infected macaques on suppressive ART were treated with 4 2-week cycles of galunisertib. ART was discontinued 3 weeks after the last dose, and macaques euthanized 6 weeks after ART-interruption(ATI). One macaque did not rebound, while the remaining rebounded between week 2 and 6 post-ATI. Galunisertib led to viral reactivation as indicated by plasma viral load and immunoPET/CT with the 64Cu-DOTA-F(ab')2-p7D3-probe. Half to 1 Log decrease in cell-associated (CA-)SIV DNA was detected in lymph nodes, gut and PBMC, while intact pro-virus in PBMC decreased by 3-fold. No systemic increase in inflammatory cytokines was observed. High-dimensions cytometry, bulk and single-cell RNAseq revealed a shift toward an effector phenotype in T and NK cells. In summary, we demonstrated that galunisertib, a clinical stage TGFβ inhibitor, reverses SIV latency and decreases SIV reservoirs by driving T cells toward an effector phenotype, enhancing immune responses in vivo in absence of toxicity.

The Role of the Transforming Growth Factor-β Signaling Pathway in Gastrointestinal Cancers

Transforming growth factor-β (TGF-β) has attracted attention as a tumor suppressor because of its potent growth-suppressive effect on epithelial cells. Dysregulation of the TGF-β signaling pathway is considered to be one of the key factors in carcinogenesis, and genetic alterations affecting TGF-β signaling are extraordinarily common in cancers of the gastrointestinal system, such as hereditary nonpolyposis colon cancer and pancreatic cancer. Accumulating evidence suggests that TGF-β is produced from various types of cells in the tumor microenvironment and mediates extracellular matrix deposition, tumor angiogenesis, the formation of CAFs, and suppression of the anti-tumor immune reaction. It is also being considered as a factor that promotes the malignant transformation of cancer, particularly the invasion and metastasis of cancer cells, including epithelial-mesenchymal transition. Therefore, elucidating the role of TGF-β signaling in carcinogenesis, cancer invasion, and metastasis will provide novel basic insight for diagnosis and prognosis and the development of new molecularly targeted therapies for gastrointestinal cancers. In this review, we outline an overview of the complex mechanisms and functions of TGF-β signaling. Furthermore, we discuss the therapeutic potentials of targeting the TGF-β signaling pathway for gastrointestinal cancer treatment and discuss the remaining challenges and future perspectives on targeting this pathway.

TGF-β Signaling Prevents MHC Class II-Expressing Lymphatic Endothelial Cells from Reactivating Human Allogenic Memory CD4+ T Cells

Lymphatic endothelial cells (LECs) express MHC class II (MHC-II) upon IFN-γ stimulation, yet recent evidence suggests that LECs cannot activate naive or memory CD4+ T cells. In this article, we show that IFN-γ-activated human dermal LECs can robustly reactivate allogeneic human memory CD4+ T cells (hCD4+ TMs), but only when TGF-β signaling is inhibited. We found that in addition to upregulating MHC-II, IFN-γ also induces LECs to upregulate glycoprotein A repetitions predominant, which anchors latent TGF-β to the membrane and potentially inhibits T cell activation. Indeed, hCD4+ TM proliferation was substantially increased when LEC-CD4+ TM cultures were treated with a TGF-β receptor type 1 inhibitor or when glycoprotein A repetitions predominant expression was silenced in LECs. Reactivated hCD4+ TMs were characterized by their proliferation, CD25 expression, and cytokine secretion. CD4+ TM reactivation was dependent on LEC expression of MHC-II, confirming direct TCR engagement. Although CD80 and CD86 were not detected on LECs, the costimulatory molecules OX40L and ICOSL were upregulated upon cytokine stimulation; however, blocking these did not affect CD4+ TM reactivation by LECs. Finally, we found that human dermal LECs also supported the maintenance of Foxp3-expressing hCD4+ TMs independently of IFN-γ-induced MHC-II. Together, these results demonstrate a role for LECs in directly modulating CD4+ TM reactivation under inflammatory conditions and point to LEC-expressed TGF-β as a negative regulator of this activation.

Cancer-associated fibroblasts: tumor defenders in radiation therapy

Cancer-associated fibroblasts (CAFs) are an important component of the tumor microenvironment that are involved in multiple aspects of cancer progression and considered contributors to tumor immune escape. CAFs exhibit a unique radiation resistance phenotype, and can survive clinical radiation doses; however, ionizing radiation can induce changes in their secretions and influence tumor progression by acting on tumor and immune cells. In this review, we describe current knowledge of the effects of radiation therapies on CAFs, as well as summarizing understanding of crosstalk among CAFs, tumor cells, and immune cells. We highlight the important role of CAFs in radiotherapy resistance, and discuss current and future radiotherapy strategies for targeting CAFs.

Transcriptional and chromatin profiling of human blood innate lymphoid cell subsets sheds light on HIV-1 pathogenesis

Innate lymphoid cells (ILCs) are a diverse population of cells that include NK cells and contribute to tissue homeostasis and repair, inflammation, and provide protection from infection. The interplay between human blood ILCs, as well as their responses to HIV-1 infection, remains poorly understood. This study used transcriptional and chromatin profiling to explore these questions. Transcriptional profiling and flow cytometry analysis support that there are four main ILC subsets found in human blood. Unlike in mice, human NK cells expressed the tissue repair protein amphiregulin (AREG). AREG production was induced by TCF7/WNT, IL-2, and IL-15, and inhibited by TGFB1, a cytokine increased in people living with HIV-1. In HIV-1 infection, the percentage of AREG+ NK cells correlated positively with the numbers of ILCs and CD4+ T cells but negatively with the concentration of inflammatory cytokine IL-6. NK-cell knockout of the TGFB1-stimulated WNT antagonist RUNX3 increased AREG production. Antiviral gene expression was increased in all ILC subsets from HIV-1 viremic people, and anti-inflammatory gene MYDGF was increased in an NK-cell subset from HIV-1-infected people whose viral load was undetectable in the absence of antiretroviral therapy. The percentage of defective NK cells in people living with HIV-1 correlated inversely with ILC percentage and CD4+ T-cell counts. CD4+ T cells and their production of IL-2 prevented the loss of NK-cell function by activating mTOR. These studies clarify how ILC subsets are interrelated and provide insight into how HIV-1 infection disrupts NK cells, including an uncharacterized homeostatic function in NK cells.

Bispecific antibody targeting TGF-β and PD-L1 for synergistic cancer immunotherapy

The PD-1/PD-L1 signaling pathway plays a crucial role in cancer immune evasion, and the use of anti-PD-1/PD-L1 antibodies represents a significant milestone in cancer immunotherapy. However, the low response rate observed in unselected patients and the development of therapeutic resistance remain major obstacles to their clinical application. Accumulating studies showed that overexpressed TGF-β is another immunosuppressive factor apart from traditional immune checkpoints. Actually, the effects of PD-1 and TGF-β pathways are independent and interactive, which work together contributing to the immune evasion of cancer cell. It has been verified that blocking TGF-β and PD-L1 simultaneously could enhance the efficacy of PD-L1 monoclonal antibody and overcome its treatment resistance. Based on the bispecific antibody or fusion protein technology, multiple bispecific and bifunctional antibodies have been developed. In the preclinical and clinical studies, these updated antibodies exhibited potent anti-tumor activity, superior to anti-PD-1/PD-L1 monotherapies. In the review, we summarized the advances of bispecific antibodies targeting TGF-β and PD-L1 in cancer immunotherapy. We believe these next-generation immune checkpoint inhibitors would substantially alter the cancer treatment paradigm, especially in anti-PD-1/PD-L1-resistant patients.

Integrins in cancer: Emerging mechanisms and therapeutic opportunities

Integrins are vital surface adhesion receptors that mediate the interactions between the extracellular matrix (ECM) and cells and are essential for cell migration and the maintenance of tissue homeostasis. Aberrant integrin activation promotes initial tumor formation, growth, and metastasis. Recently, many lines of evidence have indicated that integrins are highly expressed in numerous cancer types and have documented many functions of integrins in tumorigenesis. Thus, integrins have emerged as attractive targets for the development of cancer therapeutics. In this review, we discuss the underlying molecular mechanisms by which integrins contribute to most of the hallmarks of cancer. We focus on recent progress on integrin regulators, binding proteins, and downstream effectors. We highlight the role of integrins in the regulation of tumor metastasis, immune evasion, metabolic reprogramming, and other hallmarks of cancer. In addition, integrin-targeted immunotherapy and other integrin inhibitors that have been used in preclinical and clinical studies are summarized.

CD8+ T cells promote HIV latency by remodeling CD4+ T cell metabolism to enhance their survival, quiescence, and stemness

HIV infection persists during antiretroviral therapy (ART) due to a reservoir of latently infected cells that harbor replication-competent virus and evade immunity. Previous ex vivo studies suggested that CD8+ T cells from people with HIV may suppress HIV expression via non-cytolytic mechanisms, but the mechanisms responsible for this effect remain unclear. Here, we used a primary cell-based in vitro latency model and demonstrated that co-culture of autologous activated CD8+ T cells with HIV-infected memory CD4+ T cells promoted specific changes in metabolic and/or signaling pathways resulting in increased CD4+ T cell survival, quiescence, and stemness. Collectively, these pathways negatively regulated HIV expression and ultimately promoted the establishment of latency. As shown previously, we observed that macrophages, but not B cells, promoted latency in CD4+ T cells. The identification of CD8-specific mechanisms of pro-latency activity may favor the development of approaches to eliminate the viral reservoir in people with HIV.

Transforming Growth Factor-β1 in Cancer Immunology: Opportunities for Immunotherapy

Transforming growth factor-beta1 (TGF-β) regulates a plethora of cell-intrinsic processes that modulate tumor progression in a context-dependent manner. Thus, although TGF-β acts as a tumor suppressor in the early stages of tumorigenesis, in late stages, this factor promotes tumor progression and metastasis. In addition, TGF-β also impinges on the tumor microenvironment by modulating the immune system. In this aspect, TGF-β exhibits a potent immunosuppressive effect, which allows both cancer cells to escape from immune surveillance and confers resistance to immunotherapy. While TGF-β inhibits the activation and antitumoral functions of T-cell lymphocytes, dendritic cells, and natural killer cells, it promotes the generation of T-regulatory cells and myeloid-derived suppressor cells, which hinder antitumoral T-cell activities. Moreover, TGF-β promotes tumor-associated macrophages and neutrophils polarization from M1 into M2 and N1 to N2, respectively. Altogether, these effects contribute to the generation of an immunosuppressive tumor microenvironment and support tumor promotion. This review aims to analyze the relevant evidence on the complex role of TGF-β in cancer immunology, the current outcomes of combined immunotherapies, and the anti-TGF-β therapies that may improve the success of current and new oncotherapies.

TGF-beta signal transduction: biology, function and therapy for diseases

The transforming growth factor beta (TGF-β) is a crucial cytokine that get increasing concern in recent years to treat human diseases. This signal controls multiple cellular responses during embryonic development and tissue homeostasis through canonical and/or noncanonical signaling pathways. Dysregulated TGF-β signal plays an essential role in contributing to fibrosis via promoting the extracellular matrix deposition, and tumor progression via inducing the epithelial-to-mesenchymal transition, immunosuppression, and neovascularization at the advanced stage of cancer. Besides, the dysregulation of TGF-beta signal also involves in other human diseases including anemia, inflammatory disease, wound healing and cardiovascular disease et al. Therefore, this signal is proposed to be a promising therapeutic target in these diseases. Recently, multiple strategies targeting TGF-β signals including neutralizing antibodies, ligand traps, small-molecule receptor kinase inhibitors targeting ligand-receptor signaling pathways, antisense oligonucleotides to disrupt the production of TGF-β at the transcriptional level, and vaccine are under evaluation of safety and efficacy for the forementioned diseases in clinical trials. Here, in this review, we firstly summarized the biology and function of TGF-β in physiological and pathological conditions, elaborated TGF-β associated signal transduction. And then, we analyzed the current advances in preclinical studies and clinical strategies targeting TGF-β signal transduction to treat diseases.

Evolving therapeutic landscape of advanced hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common solid malignancies worldwide. A large proportion of patients with HCC are diagnosed at advanced stages and are only amenable to systemic therapies. We have witnessed the evolution of systemic therapies from single-agent targeted therapy (sorafenib and lenvatinib) to the combination of a checkpoint inhibitor plus targeted therapy (atezolizumab plus bevacizumab therapy). Despite remarkable advances, only a small subset of patients can obtain durable clinical benefit, and therefore substantial therapeutic challenges remain. In the past few years, emerging systemic therapies, including new molecular-targeted monotherapies (for example, donafenib), new immuno-oncology monotherapies (for example, durvalumab) and new combination therapies (for example, durvalumab plus tremelimumab), have shown encouraging results in clinical trials. In addition, many novel therapeutic approaches with the potential to offer improved treatment effects in patients with advanced HCC, such as sequential combination targeted therapy and next-generation adoptive cell therapy, have also been proposed and developed. In this Review, we summarize the latest clinical advances in the treatment of advanced HCC and discuss future perspectives that might inform the development of more effective therapeutics for advanced HCC.

Immunoregulatory signal networks and tumor immune evasion mechanisms: insights into therapeutic targets and agents in clinical development

Through activation of immune cells, the immune system is responsible for identifying and destroying infected or otherwise damaged cells including tumorigenic cells that can be recognized as foreign, thus maintaining homeostasis. However, tumor cells have evolved several mechanisms to avoid immune cell detection and killing, resulting in tumor growth and progression. In the tumor microenvironment, tumor infiltrating immune cells are inactivated by soluble factors or tumor promoting conditions and lose their effects on tumor cells. Analysis of signaling and crosstalk between immune cells and tumor cells have helped us to understand in more detail the mechanisms of tumor immune evasion and this forms basis for drug development strategies in the area of cancer immunotherapy. In this review, we will summarize the dominant signaling networks involved in immune escape and describe the status of development of therapeutic strategies to target tumor immune evasion mechanisms with focus on how the tumor microenvironment interacts with T cells.

Regulatory T Cells in Autoimmune Vasculitis

Blood vessels are indispensable for host survival and are protected from inappropriate inflammation by immune privilege. This protection is lost in patients with autoimmune vasculitides, a heterogeneous group of diseases causing damage to arteries, arterioles, and capillaries. Vasculitis leads to vascular wall destruction and/or luminal occlusion, resulting in hemorrhage and tissue ischemia. Failure in the quantity and quality of immunosuppressive regulatory T cells (Treg) has been implicated in the breakdown of the vascular immune privilege. Emerging data suggest that Treg deficiencies are disease-specific, affecting distinct pathways in distinct vasculitides. Mechanistic studies have identified faulty CD8+ Tregs in Giant Cell Arteritis (GCA), a vasculitis of the aorta and the large aortic branch vessels. Specifically, aberrant signaling through the NOTCH4 receptor expressed on CD8+ Treg cells leads to rerouting of intracellular vesicle trafficking and failure in the release of immunosuppressive exosomes, ultimately boosting inflammatory attack to medium and large arteries. In Kawasaki’s disease, a medium vessel vasculitis targeting the coronary arteries, aberrant expression of miR-155 and dysregulated STAT5 signaling have been implicated in undermining CD4+ Treg function. Explorations of mechanisms leading to insufficient immunosuppression and uncontrolled vascular inflammation hold the promise to discover novel therapeutic interventions that could potentially restore the immune privilege of blood vessels and pave the way for urgently needed innovations in vasculitis management.

Evaluation of Cell Migration and Cytokines Expression Changes under the Radiofrequency Electromagnetic Field on Wound Healing In Vitro Model

Wound healing (WH) proceeds through four distinct phases: hemostasis, inflammation, proliferation, and remodeling. Impaired WH may be the consequence of the alteration of one of these phases and represents a significant health and economic burden to millions of individuals. Thus, new therapeutic strategies are the topics of intense research worldwide. Although radiofrequency electromagnetic field (RF-EMF) has many medical applications in rehabilitation, pain associated with musculoskeletal disorders, and degenerative joint disorders, its impact on WH is not fully understood. The process of WH begins just after injury and continues during the inflammatory and proliferative phases. A thorough understanding of the mechanisms by which RF-EMF can improve WH is required before it can be used as a non-invasive, inexpensive, and easily self-applicable therapeutic strategy. Thus, the aim of this study is to explore the therapeutic potential of different exposure setups of RF-EMF to drive faster healing, evaluating the keratinocytes migration, cytokines, and matrix metalloproteinases (MMPs) expression. The results showed that RF-EMF treatment promotes keratinocytes’ migration and regulates the expression of genes involved in healing, such as MMPs, tissue inhibitors of metalloproteinases, and pro/anti-inflammatory cytokines, to improve WH.

T-Cell-Specific CerS4 Depletion Prolonged Inflammation and Enhanced Tumor Burden in the AOM/DSS-Induced CAC Model

To better understand the role of sphingolipids in the multifactorial process of inflammatory bowel disease (IBD), we elucidated the role of CerS4 in colitis and colitis-associated cancer (CAC). For this, we utilized the azoxymethane/dextran sodium sulphate (AOM/DSS)-induced colitis model in global CerS4 knockout (CerS4 KO), intestinal epithelial (CerS4 Vil/Cre), or T-cell restricted knockout (CerS4 LCK/Cre) mice. CerS4 KO mice were highly sensitive to the toxic effect of AOM/DSS, leading to a high mortality rate. CerS4 Vil/Cre mice had smaller tumors than WT mice. In contrast, CerS4 LCK/Cre mice frequently suffered from pancolitis and developed more colon tumors. In vitro, CerS4-depleted CD8+ T-cells isolated from the thymi of CerS4 LCK/Cre mice showed impaired proliferation and prolonged cytokine production after stimulation in comparison with T-cells from WT mice. Depletion of CerS4 in human Jurkat T-cells led to a constitutively activated T-cell receptor and NF-κB signaling pathway. In conclusion, the deficiency of CerS4 in T-cells led to an enduring active status of these cells and prevents the resolution of inflammation, leading to a higher tumor burden in the CAC mouse model. In contrast, CerS4 deficiency in epithelial cells resulted in smaller colon tumors and seemed to be beneficial. The higher tumor incidence in CerS4 LCK/Cre mice and the toxic effect of AOM/DSS in CerS4 KO mice exhibited the importance of CerS4 in other tissues and revealed the complexity of general targeting CerS4.

A Comprehensive Review of Calcineurin Inhibitors Used for Immunosuppression in Cardiac Transplantation

Calcineurin inhibitors (CNIs) have been the foundation of immunosuppression in solid organ transplantation since the 1980s. Cyclosporine A (CSA), the first in class, was identified as the metabolite of the soil fungus Tolypocladium inflatum Gams as part of a larger program of screening for naturally occurring fungal metabolites with biologic activity in the 1970s. Significant immunosuppressive effects were discovered and consequently CSA was trialed as an immunosuppressant in renal transplantation. This initial success led to its widespread study and adoption in solid organ transplantation. This novel agent yielded significant improvements in both 1 year and longer-term allograft and patient survival. Subsequently, a similar and more potent CNI, tacrolimus was developed. Today, it is the principal CNI used for prevention of allograft rejection. Like all other immunosuppressives, the benefits of CNIs are counterbalanced by side effects and complications resulting from drug toxicity. This chapter comprehensively reviews the clinical use of CNIs in cardiac transplantation.

Advances in Immunotherapy and the TGF-β Resistance Pathway in Metastatic Bladder Cancer

Simple Summary

Bladder cancer accounts for a significant burden to global public health. Despite advances in therapeutics with the advent of immunotherapy, only a small subset of patients benefit from immunotherapy. In this review, we examine the evidence that suggests that the TGF-β pathway may present a resistance mechanism to immunotherapy. In addition, we present possible therapies that may overcome the TGF-β resistance pathway in the treatment of bladder cancer.

Abstract

Bladder cancer accounts for nearly 200,000 deaths worldwide yearly. Urothelial carcinoma (UC) accounts for nearly 90% of cases of bladder cancer. Cisplatin-based chemotherapy has remained the mainstay of treatment in the first-line setting for locally advanced or metastatic UC. More recently, the treatment paradigm in the second-line setting was drastically altered with the approval of several immune checkpoint inhibitors (ICIs). Given that only a small subset of patients respond to ICI, further studies have been undertaken to understand potential resistance mechanisms to ICI. One potential resistance mechanism that has been identified in the setting of metastatic UC is the TGF-β signaling pathway. Several pre-clinical and ongoing clinical trials in multiple advanced tumor types have evaluated several therapies that target the TGF-β pathway. In addition, there are ongoing and planned clinical trials combining TGF-β inhibition with ICI, which may provide a promising therapeutic approach for patients with advanced and metastatic UC.

Transforming growth factor-beta1 and myeloid-derived suppressor cells: A cancerous partnership

Transforming growth factor-beta1 (TGF-β1) plays a crucial role in tumor progression. It can inhibit early cancer stages but promotes tumor growth and development at the late stages of tumorigenesis. TGF-β1 has a potent immunosuppressive function within the tumor microenvironment that largely contributes to tumor cells' immune escape and reduction in cancer immunotherapy responses. Likewise, myeloid-derived suppressor cells (MDSCs) have been postulated as leading tumor promoters and a hallmark of cancer immune evasion mechanisms. This review attempts to analyze the prominent roles of both TGF-β1 and MDSCs and their interplay in cancer immunity. Furthermore, therapies against either TGF-β1 or MDSCs, and their potential synergistic combination with immunotherapies are discussed. Simultaneous TGF-β1 and MDSCs inhibition suggest a potential improvement in immunotherapy or subverted tumor immune resistance.

Targeting TGFβ signal transduction for cancer therapy

Transforming growth factor-β (TGFβ) family members are structurally and functionally related cytokines that have diverse effects on the regulation of cell fate during embryonic development and in the maintenance of adult tissue homeostasis. Dysregulation of TGFβ family signaling can lead to a plethora of developmental disorders and diseases, including cancer, immune dysfunction, and fibrosis. In this review, we focus on TGFβ, a well-characterized family member that has a dichotomous role in cancer progression, acting in early stages as a tumor suppressor and in late stages as a tumor promoter. The functions of TGFβ are not limited to the regulation of proliferation, differentiation, apoptosis, epithelial-mesenchymal transition, and metastasis of cancer cells. Recent reports have related TGFβ to effects on cells that are present in the tumor microenvironment through the stimulation of extracellular matrix deposition, promotion of angiogenesis, and suppression of the anti-tumor immune reaction. The pro-oncogenic roles of TGFβ have attracted considerable attention because their intervention provides a therapeutic approach for cancer patients. However, the critical function of TGFβ in maintaining tissue homeostasis makes targeting TGFβ a challenge. Here, we review the pleiotropic functions of TGFβ in cancer initiation and progression, summarize the recent clinical advancements regarding TGFβ signaling interventions for cancer treatment, and discuss the remaining challenges and opportunities related to targeting this pathway. We provide a perspective on synergistic therapies that combine anti-TGFβ therapy with cytotoxic chemotherapy, targeted therapy, radiotherapy, or immunotherapy.

Biological Landscape of Triple Negative Breast Cancers Expressing CTLA-4

Patients with triple-negative breast cancer (TNBC) have a poor prognosis, partly because of the absence of targeted therapies. Recognition of the key role of immune responses against cancer has allowed the advent of immunotherapy, focused on the inhibition of negative immune checkpoints, such as CTLA-4. CTLA-4 is also expressed in some cancer cells, but its activity in tumor cells is not completely understood. Thus, the aim of the present work was to determine the biological landscape and functions of CTLA-4 expressed in TNBC cells through preclinical and in silico analysis. Exploration of CTLA-4 by immunohistochemistry in 50 TNBC tumors revealed membrane and cytoplasmic expression at different intensities. Preclinical experiments, using TNBC cell lines, showed that stimulation of CTLA-4 with CD80 enhances activation of the ERK1/2 signaling pathway, while CTLA-4 blockade by Ipilimumab induces the activation of AKT and reduces cell proliferation in vitro. We then developed an analytic pipeline to define the effects of CTLA-4 in available public data that allowed us to identify four distinct tumor clusters associated with CTLA-4 activation, which are characterized by enrichment of distinctive pathways associated with cell adhesion, MAPK signaling, TGF-ß, VEGF, TNF-α, drug metabolism, ion and amino acid transport, and KRAS signaling, among others. In addition, blockade of CTLA-4 induced increased secretion of IL-2 by tumor cells, suggesting that the receptor regulates cellular functions that may impact the immune microenvironment. This is relevant because a deep characterization of immune infiltrate, conducted using public data to estimate the abundancies of immune-cell types, showed that CTLA-4-activated-like tumors present a conditional immune state similar to an escape phenotype exploited by cancer cells. Finally, by interrogating transcriptional predictors of immunotherapy response, we defined that CTLA-4 activation correlates with high immune scores related to good clinical predicted responses to anti-CTLA-4 therapy. This work sheds new light on the roles of activated CLTA-4 in the tumor compartment and suggests an important interplay between tumor CLTA-4-activated portraits and immune-infiltrating cell populations.

The interplay between cancer associated fibroblasts and immune cells in the context of radiation therapy

Fibroblasts are a key component of the tumor microenvironment (TME) that can serve as a scaffold for tumor cell migration and augment the tumor's ability to withstand harsh conditions. When activated by external or endogenous stimuli, normal fibroblasts become cancer associated fibroblasts (CAFs), a heterogeneous group of stromal cells in the tumor that are phenotypically and epigenetically different from normal fibroblasts. Dynamic crosstalk between cancer cells, immune cells, and CAFs through chemokines and surface signaling makes the TME conducive to tumor growth. When activated, CAFs promote tumorigenesis and metastasis through several phenomena including regulation of tumor immunity, metabolic reprogramming of the TME, extracellular matrix remodeling and contraction, and induction of therapeutic resistance. Ionizing radiation (radiation theraphy [RT]) is a potent immunological stimulant that has been shown to increase cytotoxic Teff infiltration and IFN-I stimulated genes. RT, however, is unable to overcome the infiltration and activation of immunosuppressive cells which can contribute to tumor progression. Another paradox of RT is that, while very effective at killing cancer cells, it can contribute to the formation of CAFs. This review examines how the interplay between CAFs and immune cells during RT contributes to organ fibrosis, immunosuppression, and tumor growth. We focus on targeting mechanistic pathways of CAF formation as a potentially effective strategy not only for preventing organ fibrosis, but also in hampering tumor progression in response to RT.

Comprehensive Molecular Profiles of Functionally Effective MSC-Derived Extracellular Vesicles in Immunomodulation

Accumulating evidence indicates that mesenchymal stem/stromal cell-derived extracellular vesicles (MSC-EVs) exhibit immunomodulatory effects by delivering therapeutic RNAs and proteins; however, the molecular mechanism underlying the EV-mediated immunomodulation is not fully understood. In this study, we found that EVs from early-passage MSCs had better immunomodulatory potency than did EVs from late-passage MSCs in T cell receptor (TCR)- or Toll-like receptor 4 (TLR4)-stimulated splenocytes and in mice with ocular Sjögren's syndrome. Moreover, MSC-EVs were more effective when produced from 3D culture of the cells than from the conventional 2D culture. Comparative molecular profiling using proteomics and microRNA sequencing revealed the enriched factors in MSC-EVs that were functionally effective in immunomodulation. Among them, manipulation of transforming growth factor β1 (TGF-β1), pentraxin 3 (PTX3), let-7b-5p, or miR-21-5p levels in MSCs significantly affected the immunosuppressive effects of their EVs. Furthermore, there was a strong correlation between the expression levels of TGF-β1, PTX3, let-7b-5p, or miR-21-5p in MSC-EVs and their suppressive function. Therefore, our comparative strategy identified TGF-β1, PTX3, let-7b-5p, or miR-21-5p as key molecules mediating the therapeutic effects of MSC-EVs in autoimmune disease. These findings would help understand the molecular mechanism underlying EV-mediated immunomodulation and provide functional biomarkers of EVs for the development of robust EV-based therapies.

Role of TGF-β in Skin Chronic Wounds: A Keratinocyte Perspective

Chronic wounds are characterized for their incapacity to heal within an expected time frame. Potential mechanisms driving this impairment are poorly understood and current hypotheses point to the development of an unbalanced milieu of growth factor and cytokines. Among them, TGF-β is considered to promote the broadest spectrum of effects. Although it is known to contribute to healthy skin homeostasis, the highly context-dependent nature of TGF-β signaling restricts the understanding of its roles in healing and wound chronification. Historically, low TGF-β levels have been suggested as a pattern in chronic wounds. However, a revision of the available evidence in humans indicates that this could constitute a questionable argument. Thus, in chronic wounds, divergences regarding skin tissue compartments seem to be characterized by elevated TGF-β levels only in the epidermis. Understanding how this aspect affects keratinocyte activities and their capacity to re-epithelialize might offer an opportunity to gain comprehensive knowledge of the involvement of TGF-β in chronic wounds. In this review, we compile existing evidence on the roles played by TGF-β during skin wound healing, with special emphasis on keratinocyte responses. Current limitations and future perspectives of TGF-β research in chronic wounds are discussed.

Molecular feature and therapeutic perspectives of immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome

Regulatory T (Treg) cells, a subtype of immunosuppressive CD4⁺ T cells, are vital for maintaining immune homeostasis in healthy people. Forkhead box protein P3 (FOXP3), a member of the forkhead-winged-helix family, is the pivotal transcriptional factor of Treg cells. The expression, post-translational modifications, and protein complex of FOXP3 present a great impact on the functional stability and immune plasticity of Treg cells in vivo. In particular, the mutation of FOXP3 can result in immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, which is a rare genetic disease mostly diagnosed in early childhood and can soon be fatal. IPEX syndrome is related to several manifestations, including dermatitis, enteropathy, type 1 diabetes, thyroiditis, and so on. Here, we summarize some recent findings on FOXP3 regulation and Treg cell function. We also review the current knowledge about the underlying mechanism of FOXP3 mutant-induced IPEX syndrome and some latest clinical prospects. At last, this review offers a novel insight into the role played by the FOXP3 complex in potential therapeutic applications in IPEX syndrome.

Silver Decorated Mesoporous Carbons for the Treatment of Acute and Chronic Wounds, in a Tissue Regeneration Context

INTRODUCTION

Silver decorated mesoporous carbons are interesting systems that may offer effective solutions for advanced wound care products by combining the well-known anti-microbial activity of silver nanoparticles with the versatile properties of ordered mesoporous carbons. Silver is being used as a topical antimicrobial agent, especially in wound repair. However, while silver shows bactericidal properties, it is also cytotoxic at high concentrations. Therefore, the incorporation of silver into ordered mesoporous carbons allows to exploit both silver's biological effects and mesoporous carbons' biocompatibility and versatility with the purpose of conceiving silver-doped materials in light of the growing health concern in wound care.

METHODS

The wound healing potential of an ordered mesoporous carbon also doped with two different loadings of silver nanoparticles (2 wt% and 10 wt%), was investigated through a biological assessment study based on different assays (cell viability, inflammation, antibacterial tests, macrophage-conditioned fibroblast and human keratinocyte cell cultures).

RESULTS

The results show silver-doped ordered mesoporous carbons to positively condition cell viability, with a cell viability percentage >70% even for 10 wt% Ag, to modulate the expression of inflammatory cytokines and of genes involved in tissue repair (KRT6a, VEGFA, IVN) and remodeling (MMP9, TIMP3) in different cell systems. Furthermore, along with the biocompatibility and the bioactivity, the silver-doped ordered mesoporous carbons still retain an antibacterial effect, as shown by a maximum of 13.1% of inhibited area in the Halo test. The obtained results clearly showed that the silver-doped ordered mesoporous carbons exhibit both good biocompatibility and antibacterial effect with enhanced re-epithelialization, angiogenesis promotion and tissue regeneration.

DISCUSSION

These findings suggest that the exceptional properties of silver-doped ordered mesoporous carbons could be exploited in the treatment of acute and chronic wounds and that such carbon materials could be potential candidates for use in medical devices for wound healing purposes, in particular, the 10 wt% loading, as the results showed to be the most effective.

A TIGIT-based chimeric co-stimulatory switch receptor improves T-cell anti-tumor function

Background

Tumors can employ different mechanisms to evade immune surveillance and function. Overexpression of co-inhibitory ligands that bind to checkpoint molecules on the surface of T-cells can greatly impair the function of latter. TIGIT (T cell immunoreceptor with Ig and ITIM domains) is such a co-inhibitory receptor expressed by T and NK cells which, upon binding to its ligand (e.g., CD155), can diminish cytokine production and effector function. Additionally, the absence of positive co-stimulation at the tumor site can further dampen T-cell response.

Methods

As T-cell genetic engineering has become clinically-relevant in the recent years, we devised herein a strategy aimed at enhancing T-cell anti-tumor function by diverting T-cell coinhibitory signals into positive ones using a chimeric costimulatory switch receptor (CSR) composed of the TIGIT exodomain fused to the signaling domain of CD28.

Results

After selecting an optimized TIGIT-28 CSR, we co-transduced it along with tumor-specific TCR or CAR into human T-cells. TIGIT-28-equipped T-cells exhibited enhanced cytokine secretion and upregulation of activation markers upon co-culture with tumor cells. TIGIT-28 enhancing capability was also demonstrated in an original in vitro model of T-cell of hypofunction induction upon repetitive antigen exposure. Finally, we tested the function of this molecule in the context of a xenograft model of established human melanoma tumors and showed that TIGIT-28-engineered human T-cells demonstrated superior anti-tumor function.

Conclusion

Overall, we propose that TIGIT-based CSR can substantially enhance T-cell function and thus contribute to the improvement of engineered T cell-based immunotherapy.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0721-y) contains supplementary material, which is available to authorized users.

Insights into the HIV Latency and the Role of Cytokines

Human immunodeficiency virus-1 (HIV-1) has the ability to infect latently at the level of individual CD4+ cells. Latent HIV-1 proviruses are transcriptionally silent and immunologically inert, but are still capable of reactivating productive lytic infection following cellular activation. These latent viruses are the main obstacle in the eradication of HIV-1, because current HIV-1 treatment regimens are ineffective against them. Normal immunological response against an antigen activates CD4+ naïve T cells. The activated CD4+ naïve T cells undergo cell cycle, resulting in further transformation and profound proliferation to form effector CD4+ T-cells. Notably, in HIV-1 infected individuals, some of the effector CD4+ T cells get infected with HIV-1. Upon fulfillment of their effector functions, almost all activated CD4+ T cells are committed to apoptosis or programmed cell death, but a miniscule fraction revert to quiescence and become resting memory CD4+ T cells to mediate a rapid immunological response against the same antigen in the future. However, due to the quiescent nature of the resting memory T cells, the integrated HIV-1 becomes transcriptionally silent and acquires a latent phenotype. Following re-exposure to the same antigen, memory cells and integrated HIV-1 are stimulated. The reactivated latent HIV provirus subsequently proceeds through its life cycle and eventually leads to the production of new viral progeny. Recently, many strategies against HIV-1 latency have been developed and some of them have even matured to the clinical level, but none can yet effectively eliminate the latent HIV reservoir, which remains a barrier to HIV-1 cure. Therefore, alternative strategies to eradicate latent HIV need to be considered. This review provides vital knowledge on HIV latency and on strategies to supplement highly active anti-retroviral therapy (HAART) with cytokine-mediated therapeutics for dislodging the latent HIV reservoirs in order to open up new avenues for curing HIV.

TGFβ Programs Central Memory Differentiation in Ex Vivo-Stimulated Human T Cells

The adoptive transfer of ex vivo-expanded T cells is a promising approach to treat several malignancies. Several lines of evidence support that the infusion of T cells with early memory features, capable of expanding and persisting after transfer, are associated with better outcomes. We report herein that exposure to exogenous TGFβ during human T-cell stimulation ex vivo leads to the accumulation of early/central memory (Tcm) cells. Exposure to TGFβ suppressed the expression of BLIMP-1, a key orchestrator of effector T-cell differentiation, and led to the upregulation of the memory-associated transcription factor ID3. Accordingly, this was associated with an early memory transcriptional signature in both CD4⁺ and CD8⁺ T-cell subsets. The T cells stimulated in the presence of TGFβ expanded normally, and displayed polyfunctional features and no suppressive activity. The adoptive transfer of ex vivo-stimulated T cells into immunodeficient mice confirmed that TGFβ-conditioned cells had an enhanced capacity to persist and mediate xenogeneic graft-versus-host disease, as predicted by their early T-cell memory phenotype. Chimeric antigen receptor-expressing T cells generated in the presence of exogenous TGFβ were cytotoxic and more effective at controlling tumor growth in immunodeficient animals. This work unveils a new role for TGFβ in memory T-cell differentiation and indicates that TGFβ signaling may be harnessed to program Tcm differentiation in the context of ex vivo T-cell stimulation for adoptive immunotherapy in humans.

Blockade of TGF-β signaling to enhance the antitumor response is accompanied by dysregulation of the functional activity of CD4+CD25+Foxp3+ and CD4+CD25-Foxp3+ T cells

Background

The pleiotropic cytokine, transforming growth factor (TGF)-β, and CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Tregs) play a critical role in actively suppressing antitumor immune responses. Evidence shows that TGF-β produced by tumor cells promotes tolerance via expansion of Tregs. Our group previously demonstrated that blockade of TGF-β signaling with a small molecule TGF-β receptor I antagonist (SM16) inhibited primary and metastatic tumor growth in a T cell dependent fashion. In the current study, we evaluated the effect of SM16 on Treg generation and function.

Methods

Using BALB/c, FoxP3eGFP and Rag^−/− mice, we performed FACS analysis to determine if SM16 blocked de novo TGF-β-induced Treg generation in vitro and in vivo. CD4⁺ T cells from lymph node and spleen were isolated from control mice or mice maintained on SM16 diet, and flow cytometry analysis was used to detect the frequency of CD4⁺CD25⁻FoxP3⁺ and CD4⁺CD25⁺FoxP3⁺ T cells. In vitro suppression assays were used to determine the ability to suppress naive T cell proliferation in vitro of both CD4⁺CD25⁺FoxP3⁺ and CD4⁺CD25⁻FoxP3⁺ T cell sub-populations. We then examined whether SM16 diet exerted an inhibitory effect on primary tumor growth and correlated with changes in FoxP3⁺expression. ELISA analysis was used to measure IFN-γ levels after 72 h co-culture of CD4⁺CD25⁺ T cells from tumor-bearing mice on control or SM16 diet with CD4⁺CD25⁻ T cells from naive donors.

Results

SM16 abrogates TGF-β-induced Treg generation in vitro but does not prevent global homeostatic expansion of CD4⁺ T cell sub-populations in vivo. Instead, SM16 treatment causes expansion of a population of CD4⁺CD25⁻Foxp3⁺ Treg-like cells without significantly altering the overall frequency of Treg in lymphoreplete naive and tumor-bearing mice. Importantly, both the CD4⁺CD25⁻Foxp3⁺ T cells and the CD4⁺CD25⁺Foxp3⁺ Tregs in mice receiving SM16 diet exhibited diminished ability to suppress naive T cell proliferation in vitro compared to Treg from mice on control diet.

Conclusions

These findings suggest that blockade of TGF-β signaling is a potentially useful strategy for blunting Treg function to enhance the anti-tumor response. Our data further suggest that the overall dampening of Treg function may involve the expansion of a quiescent Treg precursor population, which is CD4⁺CD25⁻Foxp3⁺.

IL-23 and IL-1β Drive Human Th17 Cell Differentiation and Metabolic Reprogramming in Absence of CD28 Costimulation

Th17 cells drive autoimmune disease but also control commensal microbes. A common link among antigens from self-proteins or commensal microbiota is relatively low activation of T cell receptor (TCR) and costimulation signaling. Indeed, strong TCR/CD28 stimulation suppressed Th17 cell differentiation from human naive T cells, but not effector/memory cells. CD28 suppressed the classical Th17 transcriptional program, while inducing known Th17 regulators, and acted through an Akt-dependent mechanism. Th17 cells differentiated without CD28 were not anergic: they showed robust proliferation and maintained Th17 cytokine production following restimulation. Interleukin (IL)-23 and IL-1β promoted glucose uptake and increased glycolysis. Although modestly increased compared to CD28 costimulation, glycolysis was necessary to support Th17 differentiation, indicating that cytokine-mediated metabolic shifts were sufficient to obviate the classical requirement for CD28 in Th17 differentiation. Together, these data propose that, in humans, strength of TCR/CD28/Akt activation serves as a rheostat tuning the magnitude of Th17 development driven by IL-23 and IL-1β.

TGF-β and the Tissue Microenvironment: Relevance in Fibrosis and Cancer

Transforming growth factor-β (TGF-β) is a cytokine essential for the induction of the fibrotic response and for the activation of the cancer stroma. Strong evidence suggests that a strong cross-talk exists among TGF-β and the tissue extracellular matrix components. TGF-β is stored in the matrix as part of a large latent complex bound to the latent TGF-β binding protein (LTBP) and matrix binding of latent TGF-β complexes, which is required for an adequate TGF-β function. Once TGF-β is activated, it regulates extracellular matrix remodelling and promotes a fibroblast to myofibroblast transition, which is essential in fibrotic processes. This cytokine also acts on other cell types present in the fibrotic and tumour microenvironment, such as epithelial, endothelial cells or macrophages and it contributes to the cancer-associated fibroblast (CAF) phenotype. Furthermore, TGF-β exerts anti-tumour activity by inhibiting the host tumour immunosurveillance. Aim of this review is to update how TGF-β and the tissue microenvironment cooperate to promote the pleiotropic actions that regulate cell responses of different cell types, essential for the development of fibrosis and tumour progression. We discuss recent evidences suggesting the use of TGF-β chemical inhibitors as a new line of defence against fibrotic disorders or cancer.

TGF-β and the Tissue Microenvironment: Relevance in Fibrosis and Cancer

Transforming growth factor-β (TGF-β) is a cytokine essential for the induction of the fibrotic response and for the activation of the cancer stroma. Strong evidence suggests that a strong cross-talk exists among TGF-β and the tissue extracellular matrix components. TGF-β is stored in the matrix as part of a large latent complex bound to the latent TGF-β binding protein (LTBP) and matrix binding of latent TGF-β complexes, which is required for an adequate TGF-β function. Once TGF-β is activated, it regulates extracellular matrix remodelling and promotes a fibroblast to myofibroblast transition, which is essential in fibrotic processes. This cytokine also acts on other cell types present in the fibrotic and tumour microenvironment, such as epithelial, endothelial cells or macrophages and it contributes to the cancer-associated fibroblast (CAF) phenotype. Furthermore, TGF-β exerts anti-tumour activity by inhibiting the host tumour immunosurveillance. Aim of this review is to update how TGF-β and the tissue microenvironment cooperate to promote the pleiotropic actions that regulate cell responses of different cell types, essential for the development of fibrosis and tumour progression. We discuss recent evidences suggesting the use of TGF-β chemical inhibitors as a new line of defence against fibrotic disorders or cancer.

Resistance to TGFβ suppression and improved anti-tumor responses in CD8+ T cells lacking PTPN22

Transforming growth factor β (TGFβ) is important in maintaining self-tolerance and inhibits T cell reactivity. We show that CD8⁺ T cells that lack the tyrosine phosphatase Ptpn22, a major predisposing gene for autoimmune disease, are resistant to the suppressive effects of TGFβ. Resistance to TGFβ suppression, while disadvantageous in autoimmunity, helps Ptpn22^−/− T cells to be intrinsically superior at clearing established tumors that secrete TGFβ. Mechanistically, loss of Ptpn22 increases the capacity of T cells to produce IL-2, which overcomes TGFβ-mediated suppression. These data suggest that a viable strategy to improve anti-tumor adoptive cell therapy may be to engineer tumor-restricted T cells with mutations identified as risk factors for autoimmunity.

TGFβ secretion in the tumor microenvironment inhibits T cell-mediated anti-tumor immune responses. Here the authors show that a mutation predisposing to autoimmune diseases confers T cells resistance to TGFβ inhibitory action and could be exploited to engineer immunotherapies for TGFβ secreting tumors.

Exchange protein directly activated by cAMP modulates regulatory T-cell-mediated immunosuppression

The cAMP signalling pathway plays an essential role in immune functions. In the present study we examined the role of the cAMP/EPAC1 (exchange protein directly activated by cAMP) axis in regulatory T-cell (Treg)-mediated immunosuppression using genetic and pharmacological approaches. Genetic deletion of EPAC1 in Tregs and effector T-cells (Teffs) synergistically attenuated Treg-mediated suppression of Teffs. Mechanistically, EPAC1 inhibition enhanced activation of the transcription factor STAT3 (signal transducer and activator of transcription 3) and up-regulated SMAD7 expression while down-regulating expression of SMAD4. Consequently, CD4+ T-cells were desensitized to transforming growth factor (TGF) β1, a cytokine employed by Tregs to exert a broad inhibitory function within the immune system. Furthermore, deletion of EPAC1 led to production of significant levels of ovalbumin IgG antibodies in a low-dose, oral-tolerance mouse model. These in vivo observations are consistent with the finding that EPAC1 plays an important role in Treg-mediated suppression. More importantly, pharmacological inhibition of EPAC1 using an EPAC-specific inhibitor recapitulates the EPAC1 deletion phenotype both in vivo and in vitro. The results of the present study show that EPAC1 boosts Treg-mediated suppression, and identifies EPAC1 as a target with broad therapeutic potential because Tregs are involved in numerous pathologies, including autoimmunity, infections and a wide range of cancers.

Consumption of selenium-enriched broccoli increases cytokine production in human peripheral blood mononuclear cells stimulated ex vivo, a preliminary human intervention study

SCOPE

Selenium (Se) is a micronutrient essential for human health, including immune function. Previous research indicates that Se supplementation may cause a shift from T helper (Th)1- to Th2-type immune responses. We aim to test the potential health promoting effects of Se-enriched broccoli.

METHODS AND RESULTS

In a human trial, 18 participants consumed control broccoli daily for 3 days. After a 3-day wash-out period, the participants were provided with Se-enriched broccoli containing 200 μg of Se per serving for 3 days. Plasma and peripheral blood mononuclear cell (PBMC) samples were collected at the start and end of each broccoli feeding period for analysis of total Se and measurement of cytokine production from PBMC stimulated with antigens ex vivo. Plasma Se content remained consistent throughout the control broccoli feeding period and the baseline of the Se-enriched broccoli period (1.22 μmol/L) and then significantly increased following 3 days of Se-enriched broccoli feeding. Interleukin (IL-2, IL-4, IL-5, IL-13, and IL-22) production from PBMC significantly increased after 3 days of Se-enriched broccoli feeding compared with baseline.

CONCLUSION

This study indicates that consumption of Se-enriched broccoli may increase immune responses toward a range of immune challenges.

Intense pulsed light enhances transforming growth factor beta1/Smad3 signaling in acne-prone skin

BACKGROUND

Recently, much interest has been generated in the use of intense pulsed light (IPL) sources in the treatment of various skin conditions. However, the underlying mechanism for its therapeutic action has not been elucidated.

OBJECTIVE

To investigate the effect of IPL on the in vivo expression of transforming growth factor beta1 (TGF-β1) and on the immunolocalization of Smad3 in biopsies obtained from perilesional skin in patients with mild-to-moderate inflammatory acne vulgaris.

METHODS

Biopsies obtained from 20 patients with inflammatory acne vulgaris at baseline (B1) and post-IPL treatment (B2 = 48 h after first treatment and B3 = 1 week after final treatment) were immunohistochemically analyzed to determine the expression of TGF-β1 and the immunolocalization of Smad3. Digital images were semiquantitatively assessed using image analysis software.

RESULTS

Intense pulsed light elicited a consistent increase in epidermal TGF-β1 expression (B2 vs. B1: P = 0.004 and B3 vs. B1: P = 0.007). Furthermore, it resulted in enhanced nuclear immunolocalization of Smad3 (B2 vs. B1: epidermis, P = 0.000055 and dermis, P = 0.014; B3 vs. B1: epidermis, P = 0.00024 and dermis, P = 0.008).

CONCLUSION

Intense pulsed light upregulates TGF-β1/Smad3 signaling in perilesional skin obtained from patients with mild-to-moderate inflammatory acne vulgaris. Further experiments on lesional skin and downstream effects are warranted to determine whether it may play a role in IPL-induced resolution of acne vulgaris.

Soluble and membrane-bound TGF-β-mediated regulation of intratumoral T cell differentiation and function in B-cell non-Hodgkin lymphoma

While the effect of TGF-β on malignant B cells in non-Hodgkin lymphoma (NHL) has been previously evaluated, studies to specifically define the role of TGF-β in tumor immunity in B-cell NHL are limited. We found that soluble TGF-β, secreted by both lymphoma cells and intratumoral T cells, is present in the serum of patients with B-cell NHL. Soluble TGF-β promoted regulatory T (T_reg) cells by enhancing expression of Foxp3 in CD4⁺ T cells and suppressed effector helper T (T_H) cells by inhibiting expression of IFN-γ and IL-17. Blockade of the IL-2 signaling pathway diminished the effect of soluble TGF-β on T cell differentiation. Furthermore, we found that membrane-bound TGF-β is expressed specifically on the surface of malignant B cells in B-cell NHL. TGF-β was able to bind to the surface of lymphoma B cells through an interaction with heparan sulfate (HS) but not through the TGF-β receptor. We showed that pretreatment of lymphoma B cells with TGF-β significantly inhibits the proliferation and cytokine production of intratumoral T cells. Taken together, these results suggest that tumor-associated soluble and membrane-bound TGF-β are involved in the regulation of intratumoral T cell differentiation and function in B-cell NHL.

TGF-β conditions intestinal T cells to express increased levels of miR-155, associated with down-regulation of IL-2 and itk mRNA

Transforming growth factor (TGF)-β, is an immunosuppressive cytokine that inhibits T-cell activation. We hypothesized that TGF-β mediates its immunoinhibitory effects by modulation of micro RNA (miRNA)-155 (miR-155). Interleukin (IL)-2 and interferon-γ are down-regulated by TGF-β in activated CD4 peripheral blood T cells and lamina propria T cells (LPT), but miR-155 is upregulated ninefold specifically in LPT. Consequently, this study focuses on the role of TGF-β-enhanced miR-155 on LPT immune responses. TGF-β induces miR-155 in both freshly isolated and LPT lymphoblasts, whereas other inducible miRNAs are not regulated by TGF-β. Using MAMI bioinformatics database, we determined that inducible T-cell kinase (itk) is a functional target of miR-155 that exhibits an inverse mRNA response to that of miR-155. To determine experimentally that miR-155 regulates itk, transfection experiments were performed that demonstrated miR-155 overexpression decreased itk and IL-2 mRNA, whereas antagonism of miR-155 restored both mRNAs in activated cells. These findings describe a TGF-β-dependent function for miR-155 in modulating cytokine and T-cell immune responses in the gut.

Targeting T-cell memory: where do we stand?

PURPOSE OF REVIEW

The need to control donor-reactive T cell memory for successful organ transplantation is widely acknowledged. Alloreactive memory T cells are present in many human transplant recipients prior to transplantation and are less susceptible to the effects of currently used immunosuppression than naïve T cells. This review brings together recent advances in various fields of immunology that are potentially applicable for targeting memory T cells in sensitized transplant patients.

RECENT FINDINGS

The topics of the discussion are evoked by the latest findings on immunobiology of memory T cells and include functional diversity of T-cell memory, characteristic features of memory T-cell homeostasis and signaling, costimulatory requirements of memory T cells and their susceptibility to regulation.

SUMMARY

Despite apparent resistance of memory T cells to currently used therapies, recent findings suggest that recall responses by memory T cells can be controlled at many different levels. Use of this information may facilitate development of future tools managing T-cell memory in transplant settings.

Leukocyte function-associated antigen-1/intercellular adhesion molecule-1 interaction induces a novel genetic signature resulting in T-cells refractory to transforming growth factor-β signaling

The immunesuppressive cytokine TGF-β plays crucial regulatory roles in the induction and maintenance of immunologic tolerance and prevention of immunopathologies. However, it remains unclear how circulating T-cells can escape from the quiescent state maintained by TGF-β. Here, we report that the T-cell integrin leukocyte function-associated antigen-1 (LFA-1) interaction with its ligand intercellular adhesion molecule-1 (ICAM-1) induces a genetic signature associated with reduced TGF-β responsiveness via up-regulation of SKI, E3 ubiquitin-protein ligase SMURF2, and SMAD7 (mothers against decapentaplegic homolog 7) genes and proteins. We confirmed that the expression of these TGF-β inhibitory molecules was dependent on STAT3 and/or JNK activation. Increased expression of SMAD7 and SMURF2 in LFA-1/ICAM-1 cross-linked T-cells resulted in impaired TGF-β-mediated phosphorylation of SMAD2 and suppression of IL-2 secretion. Expression of SKI caused resistance to TGF-β-mediated suppression of IL-2, but SMAD2 phosphorylation was unaffected. Blocking LFA-1 by neutralizing antibody or specific knockdown of TGF-β inhibitory molecules by siRNA substantially restored LFA-1/ICAM-1-mediated alteration in TGF-β signaling. LFA-1/ICAM-1-stimulated human and mouse T-cells were refractory to TGF-β-mediated induction of FOXP3(+) (forkhead box P3) and RORγt(+) (retinoic acid-related orphan nuclear receptor γt) Th17 differentiation. These mechanistic data suggest an important role for LFA-1/ICAM-1 interactions in immunoregulation concurrent with lymphocyte migration that may have implications at the level of local inflammatory response and for anti-LFA-1-based therapies.

Mycobacterium tuberculosis ManLAM inhibits T-cell-receptor signaling by interference with ZAP-70, Lck and LAT phosphorylation

Immune evasion is required for Mycobacterium tuberculosis to survive in the face of robust CD4(+) T cell responses. We have shown previously that M. tuberculosis cell wall glycolipids, including mannose capped lipoarabinomannan (ManLAM), directly inhibit polyclonal murine CD4(+) T cell activation by blocking ZAP-70 phosphorylation. We extended these studies to antigen-specific murine CD4(+) T cells and primary human T cells and found that ManLAM inhibited them as well. Lck and LAT phosphorylation also were inhibited by ManLAM without affecting their localization to lipid rafts. Inhibition of proximal TCR signaling was temperature sensitive, suggesting that ManLAM insertion into T cell membranes was required. Thus, M. tuberculosis ManLAM inhibits antigen-specific CD4(+) T cell activation by interfering with very early events in TCR signaling through ManLAM's insertion in T cell membranes.

Smad7 expression in T cells prevents colitis-associated cancer

Patients with inflammatory bowel disease (IBD) have an increased risk of developing colorectal cancer due to chronic inflammation. In IBD, chronic inflammation relies upon a TGFβ signaling blockade, but its precise mechanistic relationship to colitis-associated colorectal cancer (CAC) remains unclear. In this study, we investigated the role of the TGFβ signaling inhibitor Smad7 in CAC pathogenesis. In human colonic specimens, Smad7 was downregulated in CD4(+) T cells located in the lamina propria of patients with complicated IBD compared with uncomplicated IBD. Therefore, we assessed CAC susceptibility in a transgenic mouse model where Smad7 was overexpressed specifically in T cells. In this model, Smad7 overexpression increased colitis severity, but the mice nevertheless developed fewer tumors than nontransgenic mice. Protection was associated with increased expression of IFNγ and increased accumulation of cytotoxic CD8(+) and natural killer T cells in the tumors and peritumoral areas. Moreover, genetic deficiency in IFNγ abolished the Smad7-dependent protection against CAC. Taken together, our findings defined a novel and unexpected role for Smad7 in promoting a heightened inflammatory response that protects against CAC.

Polymorphisms of transforming growth factor-β signaling pathway and Kawasaki disease in the Taiwanese population

Kawasaki disease (KD) is a systemic vasculitis associated with cardiovascular symptom. A previous study in the European descent has indicated that genetic variants of the transforming growth factor-β (TGF-β) pathway are involved in the KD susceptibility and clinical status. This study was conducted to investigate if polymorphisms in TGF-β signaling pathway are associated with KD susceptibility, and the coronary artery lesion formation. A total of 950 subjects (381 KD patients and 569 controls) were investigated to identify 12 single-nucleotide polymorphisms in the TGF-β signaling pathway (rs2796817, rs10482751, rs2027567, rs12029576, rs11466480, rs4776338, rs12901071, rs7162912, rs1438386, rs6494633, rs12910698 and rs4776339) by using TaqMan Allelic Discrimination assay. Our results indicated that rs1438386 in the SMAD3 is significantly associated with the susceptibility of KD. Additionally, both haplotypes of TGFβ2 and SMAD3 were also associated with the risk of KD. This study showed that genetic polymorphisms in TGF-β signaling pathway are associated with KD susceptibility, but not coronary artery lesions formation, or intravenous immunoglobulin treatment response in the Taiwanese population.

TGF-β stimulates biglycan core protein synthesis but not glycosaminoglycan chain elongation via Akt phosphorylation in vascular smooth muscle

Transforming growth factor-β (TGF-β) can mediate proteoglycan synthesis via Smad and non-Smad signalling pathways in vascular smooth muscle (VSM). We investigated whether TGF-β-mediated proteoglycan synthesis is via PI3K/Akt. TGF-β induced a rapid phosphorylation of Akt that continued upto 4 h. Akt phosphorylation was blocked by Akt1/2 inhibitor SN30978; however, it did not block Smad2 phosphorylation at either the carboxy or linker regions indicating that TGF-β-mediated Akt phosphorylation is independent of Smad2 signalling. The role of Akt in TGF-β-mediated proteoglycan synthesis was investigated. Treatment with SN30978 showed a concentration-dependent decrease in TGF-β-mediated [(35)S]-sulphate and [(35)S]-Met/Cys incorporation into secreted proteoglycans; however, SDS-PAGE showed no change in biglycan size. In TGF-β-treated cells, biglycan mRNA levels increased by 40-100% in 24 h and was significantly blocked by SN30978. Our findings demonstrate that Akt is a downstream signalling component of TGF-β-mediated biglycan core protein synthesis but not glycosaminoglycan chain hyper-elongation in VSM.