Robust tumor immunity to melanoma mediated by interleukin-9-producing T cells

Molecular Aspects and Future Perspectives of Cytokine-Based Anti-cancer Immunotherapy

Cytokine-based immunotherapy is a promising field in the cancer treatment, since cytokines, as proteins of the immune system, are able to modulate the host immune response toward cancer cell, as well as directly induce tumor cell death. Since a low dose monotherapy with some cytokines has no significant therapeutic results and a high dose treatment leads to a number of side effects caused by the pleiotropic effect of cytokines, the problem of understanding the influence of cytokines on the immune cells involved in the pro- and anti-tumor immune response remains a pressing one. Immune system cells carry CD makers on their surface which can be used to identify various populations of cells of the immune system that play different roles in pro- and anti-tumor immune responses. This review discusses the functions and specific CD markers of various immune cell populations which are reported to participate in the regulation of the immune response against the tumor. The results of research studies and clinical trials investigating the effect of cytokine therapy on the regulation of immune cell populations and their surface markers are also discussed. Current trends in the development of cancer immunotherapy, as well as the role of cytokines in combination with other therapeutic agents, are also discussed.

Disease swamps molecular signatures of genetic-environmental associations to abiotic factors in Tasmanian devil (Sarcophilus harrisii) populations

Landscape genomics studies focus on identifying candidate genes under selection via spatial variation in abiotic environmental variables, but rarely by biotic factors (i.e., disease). The Tasmanian devil (Sarcophilus harrisii) is found only on the environmentally heterogeneous island of Tasmania and is threatened with extinction by a transmissible cancer, devil facial tumor disease (DFTD). Devils persist in regions of long-term infection despite epidemiological model predictions of species' extinction, suggesting possible adaptation to DFTD. Here, we test the extent to which spatial variation and genetic diversity are associated with the abiotic environment (i.e., climatic variables, elevation, vegetation cover) and/or DFTD. We employ genetic-environment association analyses using 6886 SNPs from 3287 individuals sampled pre- and post-disease arrival across the devil's geographic range. Pre-disease, we find significant correlations of allele frequencies with environmental variables, including 365 unique loci linked to 71 genes, suggesting local adaptation to abiotic environment. The majority of candidate loci detected pre-DFTD are not detected post-DFTD arrival. Several post-DFTD candidate loci are associated with disease prevalence and were in linkage disequilibrium with genes involved in tumor suppression and immune response. Loss of apparent signal of abiotic local adaptation post-disease suggests swamping by strong selection resulting from the rapid onset of DFTD.

Engineering bionic T cells: signal 1, signal 2, signal 3, reprogramming and the removal of inhibitory mechanisms

Gene engineering and combinatorial approaches with other cancer immunotherapy agents may confer capabilities enabling full tumor rejection by adoptive T cell therapy (ACT). The provision of proper costimulatory receptor activity and cytokine stimuli, along with the repression of inhibitory mechanisms, will conceivably make the most of these treatment strategies. In this sense, T cells can be genetically manipulated to become refractory to suppressive mechanisms and exhaustion, last longer and differentiate into memory T cells while endowed with the ability to traffic to malignant tissues. Their antitumor effects can be dramatically augmented with permanent or transient gene transfer maneuvers to express or delete/repress genes. A combination of such interventions seeks the creation of the ultimate bionic T cell, perfected to seek and destroy cancer cells upon systemic or local intratumor delivery.

Th9 Cell Differentiation and Its Dual Effects in Tumor Development

With the improved understanding of the molecular pathogenesis and characteristics of cancers, the critical role of the immune system in preventing tumor development has been widely accepted. The understanding of the relationship between the immune system and cancer progression is constantly evolving, from the cancer immunosurveillance hypothesis to immunoediting theory and the delicate balance in the tumor microenvironment. Currently, immunotherapy is regarded as a promising strategy against cancers. Although adoptive cell therapy (ACT) has shown some exciting results regarding the rejection of tumors, the effect is not always satisfactory. Cellular therapy with CD4⁺ T cells remains to be further explored since the current ACT is mainly focused on CD8⁺ cytotoxic T lymphocytes (CTLs). Recently, Th9 cells, a subgroup of CD4⁺ T helper cells characterized by the secretion of IL-9 and IL-10, have been reported to be effective in the elimination of solid tumors and to exhibit superior antitumor properties to Th1 and Th17 cells. In this review, we summarize the most recent advances in the understanding of Th9 cell differentiation and the dual role, both anti-tumor and pro-tumor effects, of Th9 cells in tumor progression.

Immunomodulatory dynamics of excretory and secretory products on Th9 immune response during Haemonchus contortus infection in goat

CD4+ T cells play critical roles in mediating adaptive immunity to a variety of pathogens. Recently, new subset of CD4+T named as T helper 9 cells that express the prototypical interleukin-9 (IL-9) cytokine have been recognized in human and mice models during different parasitic infections. Haemonchus contortus is a gastrointestinal nematode of small ruminants which cause high mortality in young animals. During infection, Excretory and Secretary Products (ESPs) are released in the host body. No other study has reported yet on immunomodulatory dynamics of H. contortus ESPs on Th9 immune response in vitro or in vivo. In this study, immunomodulatory effects of ESPs (5, 10, 20, 40, 80; μg/mL) incubated with goat PBMCs on Th9 cells, IL-9 immune response and TGF-β/Smad signaling regulator were evaluated in vitro. Moreover, for in vivo study, goats were infected with different doses (P-800, P-2400, and P-8000) of H. contortus infective larva (L3) and immunomodulatory effects on Th9 cells, IL-9 immune response and TGF-β/Smad signaling regulator were evaluated at 7, 10, 14, 18, 21, 28 Days Post Infection (DPI). Flow cytometry was performed to evaluate the effects on Th9 cells and quantitative real time polymerase chain reaction was performed to evaluate the IL-9 cytokine transcription level. Additionally, fecal egg counting was also performed in parallel to confirm the infection. All goats were dewormed at 29 DPI and all experiments were also performed at 35 DPI, one week post deworming. The finding indicated that 10, 20, 40, 80 μg/mL concentration of ESPs incubated with goat PBMCs showed significant increase in the production of Th9 cells, signature cytokine IL-9 and expression of TGF-β/Smad signaling regulator as compared to control group in vitro.All infected groups showed significant increase in production of Th9 cells and IL-9 cytokine and expression of TGF-β/Smad key genes at 18, 21, and 28 DPI as compared to control group. Likewise, at 14 DPI, P-2400 and P-8000 groups showed significant increase in production of Th9 cells, IL-9 cytokine and expression of TGF-β/Smad key genes. While at 10 DPI, production of Th9 cells and IL-9 was significantly increased in P-2400 & P-8000 groups, and at 7 DPI only P-8000 showed significantly increase in IL-9 production. No immunomodulatory effects were observed at 0 and 3 DPI. Additionally, significant gradually up-regulated key genes expression of TGF-β/Smad signaling regulator in all infected groups confirmed the above results. After deworming, production of Th9 cells, associated immune response and expression of signaling regulator in each group were significantly decreased. Based on this study, it is concluded that Th9 immune response was induced during H. contortus infection in goat by up-regulation of TGF-β/Smad signaling key genes.

Haemonchus contortus is one of the most pathogenic nematodes of small ruminants in tropical and sub-tropical areas of the world. This parasite is responsible for anemia, edema, and death in young animal which can lead to billions of economic losses globally. Excretory and secretory products (ESPs) are produced by the parasite to modulate the immune response and to protect both parasite and the host. Th9 cells are a subset of CD4+ T cells producing IL-9 cytokine. Th9 cells were increasingly recognized for being important in immunity to intestinal infection with helminths. In this study, immunomodulatory effects of ESPs on PBMCs derived Th9 cells, IL-9 cytokine and TGF-β/Smad signalling were evaluated in vitro and in vivo. Furthermore, Th9 cells production was significantly enhanced on 7, 10, 14, 18, 21, and 28 Days Post Infection (DPI), while no effect was observed at 0 and 3 DPI in vivo. Moreover, the production of IL-9 and TGF-β/Smad Pathway key genes increased gradually from 7 to 28 DPI in vivo. After deworming, production of Th9 cells was gradually decreased in each group.

Mast cell-based molecular subtypes and signature associated with clinical outcome in early-stage lung adenocarcinoma

Mast cells are a major component of the immune microenvironment in tumour tissues and modulate tumour progression by releasing pro‐tumorigenic and antitumorigenic molecules. Regarding the impact of mast cells on the outcomes of patients with lung adenocarcinoma (LUAD) patient, several published studies have shown contradictory results. Here, we aimed at elucidating the role of mast cells in early‐stage LUAD. We found that high mast cell abundance was correlated with prolonged survival in early‐stage LUAD patients. The mast cell‐related gene signature and gene mutation data sets were used to stratify early‐stage LUAD patients into two molecular subtypes (subtype 1 and subtype 2). The neural network‐based framework constructed with the mast cell‐related signature showed high accuracy in predicting response to immunotherapy. Importantly, the prognostic mast cell‐related signature predicted the survival probability and the potential relationship between TP53 mutation, c‐MYC activation and mast cell activities. The meta‐analysis confirmed the prognostic value of the mast cell‐related gene signature. In summary, this study might improve our understanding of the role of mast cells in early‐stage LUAD and aid in the development of immunotherapy and personalized treatments for early‐stage LUAD patients.

IL-9 and IL-9-producing cells in tumor immunity

Abstract

Interleukin (IL)-9 belongs to the IL-2Rγc chain family and is a multifunctional cytokine that can regulate the function of many kinds of cells. It was originally identified as a growth factor of T cells and mast cells. In previous studies, IL-9 was mainly involved in the development of allergic diseases, autoimmune diseases and parasite infections. Recently, IL-9, as a double-edged sword in the development of cancers, has attracted extensive attention. Since T-helper 9 (Th9) cell-derived IL-9 was verified to play a powerful antitumor role in solid tumors, an increasing number of researchers have started to pay attention to the role of IL-9-skewed CD8⁺ T (Tc9) cells, mast cells and Vδ2 T cell-derived IL-9 in tumor immunity. Here, we review recent studies on IL-9 and several kinds of IL-9-producing cells in tumor immunity to provide useful insight into tumorigenesis and treatment.

Changes and significance of T helper-9 cells and interleukin-9 in patients with atherosclerotic chronic lower limb ischemia: Effect on IL-17 release

OBJECTIVES

Atherosclerosis is considered as a chronic inflammatory disorder where the central role of T cells in its pathogenesis is well known. T helper-9 cells have a distinctive effect upon the inflammatory processes. They stimulate macrophages via secretion of their cytokine interleukin-9. Based on its known involvement with other inflammatory disorders, we hypothesized that interleukin-9 might be associated with the inflammatory limb of peripheral atherosclerotic disease.

METHODS

We tested this hypothesis on peripheral blood mononuclear cells (PBMCs) and freshly resected arterial tissues from 84 patients with peripheral arterial occlusive disease (PAOD) and 50 non-atherosclerotic subjects. A number of experimental methods were used including flow cytometry analysis of T helper-9 cells using anti-CD3, anti-CD4, and anti-interleukin-9monoclonal antibodies as well as real-time polymerase chain reaction for the assessment of gene expression of interleukin-9. In addition, circulating serum levels of interleukin-9 were measured using enzyme linked immunosorbent assay. We also evaluated the ability of recombinant interleukin-9 to modulate IL-17 release in cultured isolated CD3+ T cells with relation to atherosclerotic disorder in vitro.

RESULTS AND CONCLUSIONS

Here we report increased percentages of T helper-9 cells and interleukin-9 levels in patients with chronic lower limb atherosclerotic ischemia, compared to healthy controls. Through investigation of different atherosclerotic patient populations with different disease stages, we found elevated interleukin-9 level both systemically and within the lesion and increased expression of cells in severe disease stages. The current study also revealed enhanced expression of mRNA levels of interleukin-9 within the atherosclerotic lesion when compared with non-atherosclerotic vessels. Levels of released IL-17 in CD3+ T cell culture supernatants supplemented with interleukin-9 were significantly positively correlated in the enrolled patients. The results suggest a role for T helper-9 cells and IL-9 in atherosclerotic process, potentially involving IL-17-mediated mechanisms. Indeed, we found that interleukin-9 promoted IL-17 release in PBMCs, with a particularly marked response in severe disease.

Targeting the IL-9 pathway in cancer immunotherapy

Interleukin (IL)-9 is a pleiotropic cytokine, which can function as a positive or negative regulator of immune responses on multiple types of cells. The role of IL-9 was originally known in allergic disease and parasite infections. Interestingly, recent studies demonstrate its presence in the tumor tissues of mice and humans, and the association between IL-9 and tumor progression has been revisited following the discovery of T helper (Th) 9 cells. Tumor-specific Th9 cells are considered to be the main subset of CD4⁺ T cells that produce high level of IL-9 and exhibit an IL-9-dependent robust anti-cancer function in solid tumors. IL-9 exerts an unprecedented anti-tumor immunity not only by inducing innate and adaptive immune responses but also directly promoting apoptosis of tumor cells. The objective of this review is to summarize the latest advances regarding the anti-tumor mechanisms of IL-9 and Th9 cells.

Pleiotropic Role and Bidirectional Immunomodulation of Innate Lymphoid Cells in Cancer

Innate lymphoid cells (ILCs) are largely tissue resident and respond rapidly toward the environmental signals from surrounding tissues and other immune cells. The pleiotropic function of ILCs in diverse contexts underpins its importance in the innate arm of immune system in human health and disease. ILCs derive from common lymphoid progenitors but lack adaptive antigen receptors and functionally act as the innate counterpart to T-cell subsets. The classification of different subtypes is based on their distinct transcription factor requirement for development as well as signature cytokines that they produce. The discovery and subsequent characterization of ILCs over the past decade have mainly focused on the regulation of inflammation, tissue remodeling, and homeostasis, whereas the understanding of the multiple roles and mechanisms of ILCs in cancer is still limited. Emerging evidence of the potent immunomodulatory properties of ILCs in early host defense signifies a major advance in the use of ILCs as promising targets in cancer immunotherapy. In this review, we will decipher the non-exclusive roles of ILCs associated with both protumor and antitumor activities. We will also dissect the heterogeneity, plasticity, genetic evidence, and dysregulation in different cancer contexts, providing a comprehensive understanding of the complexity and diversity. These will have implications for the therapeutic targeting in cancer.

Targeting cancer cells with nanotherapeutics and nanodiagnostics: Current status and future perspectives

Nanotechnology is reshaping health care strategies and is expected to exert a tremendous impact in the coming years offering better healthcare facilities. It has led to not only therapeutic drug delivery feasibility but also to diagnostics. Materials in the size of nano range (1-100 nm) used in the design, fabrication, regulation, and application of therapeutic drugs or devices are classified as medical nanotechnology and nanopharmacology. Delivery of more complex molecules to the specific site of action as well as gene therapy has pushed forward the nanoparticle-based drug delivery to its maximum. Areas that benefit from nano-based drug delivery systems are cancer, diabetes, infectious diseases, neurodegenerative diseases, blood disorders and orthopedic-related ailments. Moreover, development of nanotherapeutics with multi-functionalities has a considerable potential to fill the gaps that exist in the present therapeutic domain. In cancer treatment, nanomedicines have superiority over current therapeutic practices as they can effectively deliver the drug to the affected tissues, thus reducing drug toxicities. Along this line, polymeric conjugates of asparaginase and polymeric micelles of paclitaxel have recently been recommended for the treatment of various types of cancers. Nanotechnology-based therapeutics and diagnostics provide greater effectiveness with less or no toxicity concerns. Similarly, diagnostic imaging holds promising future applications with newer nano-level imaging elements. Advancements in nanotechnology have emerged to a newer direction which use nanorobotics for various applications in healthcare. Accordingly, this review comprehensively highlights the potentialities of various nanocarriers and nanomedicines for multifaceted applications in diagnostics and drug delivery, especially the potentialities of polymeric nanoparticle, nanoemulsion, solid-lipid nanoparticle, nanostructured lipid carrier, self-micellizing anticancer lipids, dendrimer, nanocapsule and nanosponge-based therapeutic approaches in the field of cancer. Furthermore, this article summarizes the most recent literature pertaining to the use of nano-technology in the field of medicine, particularly in treating cancer patients.

The Th9 Axis Reduces the Oxidative Stress and Promotes the Survival of Malignant T Cells in Cutaneous T-Cell Lymphoma Patients

Immune dysfunction is critical in pathogenesis of cutaneous T-cell lymphoma (CTCL). Few studies have reported abnormal cytokine profile and dysregulated T-cell functions during the onset and progression of certain types of lymphoma. However, the presence of IL9-producing Th9 cells and their role in tumor cell metabolism and survival remain unexplored. With this clinical study, we performed multidimensional blood endotyping of CTCL patients before and after standard photo/chemotherapy and revealed distinct immune hallmarks of the disease. Importantly, there was a higher frequency of "skin homing" Th9 cells in CTCL patients with early (T1 and T2) and advanced-stage disease (T3 and T4). However, advanced-stage CTCL patients had severely impaired frequency of skin-homing Th1 and Th17 cells, indicating attenuated immunity. Treatment of CTCL patients with standard photo/chemotherapy decreased the skin-homing Th9 cells and increased the Th1 and Th17 cells. Interestingly, T cells of CTCL patients express IL9 receptor (IL9R), and there was negligible IL9R expression on T cells of healthy donors. Mechanistically, IL9/IL9R interaction on CD3⁺ T cells of CTCL patients and Jurkat cells reduced oxidative stress, lactic acidosis, and apoptosis and ultimately increased their survival. In conclusion, coexpression of IL9 and IL9R on T cells in CTCL patients indicates the autocrine-positive feedback loop of Th9 axis in promoting the survival of malignant T cells by reducing the oxidative stress. IMPLICATIONS: The critical role of Th9 axis in CTCL pathogenesis indicates that strategies targeting Th9 cells might harbor significant potential in developing robust CTCL therapy.

Role of IL-9 and IL-10 in the pathogenesis of chronic spontaneous urticaria through the JAK/STAT signalling pathway

This study investigated the role of interleukin (IL)-9 and IL-10 in the pathogenesis of chronic spontaneous urticaria (CSU). Autologous serum skin test and histamine release test were performed in CSU patients and normal subjects. Kunming mice were used to develop a mouse model for CSU. We induced IL-9 overexpression, IL-10 overexpression, and JAK/STAT pathway inhibition as well as a combination of all three conditions in CSU and control mice. Eosinophils in the skin tissues, inflammatory cytokine expression, and distribution of T lymphocyte subsets in peripheral blood of mice were detected. Expression patterns of IL-9, IL-10, STAT3, JAK2, and INF-γ in clinical samples and mice were detected by reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot analysis. The positive rate of autologous serum skin test and the histamine release rate of CSU patients, compared with normal subjects, were apparently elevated. Compared with controls, mice with CSU experienced longer duration and higher frequency of pruritus and demonstrated enhanced levels of CD8⁺ , the ratio of CD4⁺ /CD8⁺ , number of eosinophils, and inflammatory cytokine expression in serum as well as activated JAK/STAT signalling pathway; at the same time, levels of CD4⁺ and INF-γ were reduced. This trend was found in CSU mice overexpressing IL-9 and IL-10 when compared with the CSU mice without treatment. In contrast, JAK/STAT inhibition reversed the above trend. Overall, our study suggests that IL-9 and IL-10 contribute to CSU development via activation of the JAK/STAT signalling pathway.

Hitting More Birds with a Stone: Impact of TGF-β on ILC Activity in Cancer

Transforming growth factor (TGF)-β is a central immunosuppressive cytokine within tumor microenvironment inhibiting the expansion and function of major cellular components of adaptive and innate immune system. Among them, compelling evidence has demonstrated that TGF-β is a key regulator of natural killer (NK) cells, innate lymphoid cells (ILCs) with a critical role in immunosurveillance against different kinds of cancer cells. A TGF-β rich tumor microenvironment blocks NK cell activity at multiple levels. This immunosuppressive factor exerts direct regulatory effects on NK cells including inhibition of cytokine production, alteration of activating/inhibitory receptor expression, and promotion of the conversion into non cytotoxic group I ILC (ILC1). Concomitantly, TGF-β can render tumor cells less susceptible to NK cell-mediated recognition and lysis. Indeed, accumulating evidence suggest that changes in levels of NKG2D ligands, mainly MICA, as well as an increase of immune checkpoint inhibitors (e.g., PD-L1) and other inhibitory ligands on cancer cells significantly contribute to TGF-β-mediated suppression of NK cell activity. Here, we will take into consideration two major mechanisms underlying the negative regulation of ILC function by TGF-β in cancer. First, we will address how TGF-β impacts the balance of signals governing NK cell activity. Second, we will review recent advances on the role of this cytokine in driving ILC plasticity in cancer. Finally, we will discuss how the development of therapeutic approaches blocking TGF-β may reverse the suppression of host immune surveillance and improve anti-tumor NK cell response in the clinic.

Th2 cells as an intermediate for the differentiation of naïve T cells into Th9 cells, associated with the Smad3/Smad4 and IRF4 pathway

Type 9 T-helper (Th9) cells are associated with atopic and inflammatory diseases. Their increased levels and functions contribute to a number of inflammatory disorders, where they are accompanied by enhanced Th2-cell activity. However, there is currently no consensus regarding the association between Th9 and Th2 cells. Th9 cells may be induced from naïve T (Th0) cells under specific polarization conditions in vitro, a process driven by the addition of specific cytokines. In the present study, Th0 cells were cultured under Th9-polarizing conditions to promote differentiation into interleukin (IL)-4⁺ IL-9^- or IL-4^- IL-9⁺ T cells after 3 or 5 days in culture, respectively; the mRNA expression levels of IL-9 and IL-4 were consistent with the induced cell types. Simultaneously, the levels of interferon-regulatory factor 4 (IRF-4) and Smad3/Smad4 were significantly increased following Th9-cell polarization. It was therefore proposed that Th2 cells may be generated in the early stages of Th9-cell differentiation, and then ultimately differentiate into Th9 cells via the Smad3/Smad4 and IRF-4 activation pathway.

Janus or Hydra: The Many Faces of T Helper Cells in the Human Tumour Microenvironment

CD4+ T helper (T_H) cells are key regulators in the tumour immune microenvironment (TIME), mediating the adaptive immunological response towards cancer, mainly through the activation of cytotoxic CD8+ T cells. After antigen recognition and proper co-stimulation, naïve T_H cells are activated, undergo clonal expansion, and release cytokines that will define the differentiation of a specific effector T_H cell subtype. These different subtypes have different functions, which can mediate both anti- and pro-tumour immunological responses. Here, we present the dual role of T_H cells restraining or promoting the tumour, the factors controlling their homing and differentiation in the TIME, their influence on immunotherapy, and their use as prognostic indicators.

IL-9 Exerts Antitumor Effects in Colon Cancer and Transforms the Tumor Microenvironment In Vivo

As a newly discovered cytokine, interleukin 9 was initially considered a T-lymphocyte growth factor. Interleukin 9 affects target cells by binding to a member of the γc-family of receptors and is involved in inflammation, autoimmune diseases, and other ailments. In recent years, mounting evidence reveals that interleukin 9 exerts antitumor effects, which has attracted considerable attention. Many previous studies were performed in vivo by establishing a mouse model of melanoma. Here, interleukin 9 protein and messenger RNA expression levels were both low in colon carcinoma tissue specimens, as assessed by immunohistochemistry and quantitative real-time polymerase chain reaction. In addition, interleukin 9 expression in these samples was correlated with TNM staging, Dukes staging, lymph node metastasis, and good prognosis, but not with gender, age, tumor size, tumor differentiation, and hepatic metastasis. In vivo, by establishing a mouse subcutaneous allograft model, we found that interleukin 9 overexpression inhibited tumor growth and resulted in longer survival time. Then, antitumor immune responses were increased by interleukin 9 as demonstrated by flow cytometry. Furthermore, interleukin 9 was shown to exert antitumor effects by regulating T-cell function and killing tumor cells in the tumor microenvironment. Overall, this study revealed that interleukin 9 exerts robust antitumor effects in colon cancer and transforms the tumor microenvironment in vivo.

IL-9 Controls Central Nervous System Autoimmunity by Suppressing GM-CSF Production

Multiple sclerosis and experimental autoimmune encephalomyelitis (EAE) are inflammatory diseases of the CNS in which Th17 cells play a major role in the disease pathogenesis. Th17 cells that secrete GM-CSF are pathogenic and drive inflammation of the CNS. IL-9 is a cytokine with pleiotropic functions, and it has been suggested that it controls the pathogenic inflammation mediated by Th17 cells, and IL-9R^-/- mice develop more severe EAE compared with wild-type counterparts. However, the underlying mechanism by which IL-9 suppresses EAE has not been clearly defined. In this study, we investigated how IL-9 modulates EAE development. By using mice knockout for IL-9R, we show that more severe EAE in IL-9R^-/- mice correlates with increased numbers of GM-CSF⁺ CD4⁺ T cells and inflammatory dendritic cells (DCs) in the CNS. Furthermore, DCs from IL-9R^-/- mice induced more GM-CSF production by T cells and exacerbated EAE upon adoptive transfer than did wild-type DCs. Our results suggest that IL-9 reduces autoimmune neuroinflammation by suppressing GM-CSF production by CD4⁺ T cells through the modulation of DCs.

CD4+ T Cell Help Is Required for the Formation of a Cytolytic CD8+ T Cell Subset that Protects against Chronic Infection and Cancer

Although CD4⁺ T cell "help" is crucial to sustain antiviral immunity, the mechanisms by which CD4⁺ T cells regulate CD8⁺ T cell differentiation during chronic infection remain elusive. Here, using single-cell RNA sequencing, we show that CD8⁺ T cells responding to chronic infection were more heterogeneous than previously appreciated. Importantly, our findings uncovered the formation of a CX₃CR1-expressing CD8⁺ T cell subset that exhibited potent cytolytic function and was required for viral control. Notably, our data further demonstrate that formation of this cytotoxic subset was critically dependent on CD4⁺ T cell help via interleukin-21 (IL-21) and that exploitation of this developmental pathway could be used therapeutically to enhance the killer function of CD8⁺ T cells infiltrated into the tumor. These findings uncover additional molecular mechanisms of how "CD4⁺ T cell help" regulates CD8⁺ T cell differentiation during persistent infection and have implications toward optimizing the generation of protective CD8⁺ T cells in immunotherapy.

BATF3 is sufficient for the induction of Il9 expression and can compensate for BATF during Th9 cell differentiation

Th9 cells preferentially produce IL-9 and participate in allergic responses and asthma. Differentiation of Th9 cells is induced by IL-4 and TGF-β, and then the cells are amplified by OX40 signals. The transcription factors PU.1, IRF4, and BATF are required for Th9 differentiation. BATF3 is an AP-1 family transcription factor that is highly homologous to BATF; however, its role in Th9 cells is poorly defined. Here, we show that OX40 signaling induced the expression of Batf3 and that its overexpression in the presence or absence of OX40 signaling increased the expression of IL-9 in Th9 cells. BATF3 physically interacted with IRF4 and was bound to the Il9 locus. A transient reporter assay revealed that the BATF3–IRF4 complex induced Il9 promoter activity. BATF3 rescued Il9 expression and restored the capacity to induce the airway inflammation in Batf KO Th9 cells. Thus, BATF3 itself is sufficient for the induction of Th9 cell differentiation and can substitute for BATF during Th9 cell differentiation.

A protein that regulates gene expression in immune cells may contribute to airway inflammation in asthma and allergies. A subset of immune cells known as Th9 cells plays a prominent role in these respiratory disorders, and researchers led by Gap Ryol Lee at Sogang University in Seoul, South Korea, set out to characterize signaling mechanisms that promote Th9 production. They focused specifically on a protein called BATF3, which regulates genes responsible for maturation of a variety of other immune cell types, but whose role with regard to Th9 is poorly understood. They determined that BATF3 has a potent effect in terms of inducing Th9 cell activity, and can even take the place of another known Th9-inducing protein. These findings could assist in the development of treatments that keep airway-constricting inflammation in check.

Th9 cells are subjected to PD-1/PD-L1-mediated inhibition and are capable of promoting CD8 T cell expansion through IL-9R in colorectal cancer

Th9 cells are named after their expression of IL-9. Studies in recent years demonstrated that Th9 cells could contribute to antitumor immunity by enhancing the recruitment and activation of mast cells, natural killer cells, CD8 T cells, and dendritic cells in the tumor microenvironment. To determine whether Th9 cells participate in colorectal cancer (CRC), we collected resected tumor samples from 20 CRC patients. In the tumor-infiltrating lymphocytes (TILs), IL-9⁺IL-4^- CD4⁺ T cells could be observed and were present at higher frequencies than the IL-9⁺IL-4⁺ and the IL-9^-IL-4⁺ cells, suggesting that the majority of IL-9-producing TILs were bona fide Th9 cells. IL-9-secreting TILs presented particularly high PD-1 expression directly ex vivo. The expression of IL-9 was significantly reduced with PD-L1-mediated inhibition, which in turn was suppressed by anti-PD-1 blocking. Interestingly, the circulating CD4⁺ T cell compartment in CRC patients also presented Th9 enrichment, characterized by higher IL-9⁺IL-4^- and IL-9⁺IL-4⁺ cell frequencies in the CXCR3^-CCR6^- compartment as compared to that in non-cancer controls. Using exogenous TGF-β and IL-4, we were capable of enriching Th9 cells without concurrent enrichment of Th2 cells. Th9-enriched CD4⁺ T cells, but not Th9-non-enriched cells, significantly increased the expansion of activated CD8⁺ T cells, in a manner that was dependent on the expression of IL-9R. In addition, the frequencies of Th9 cells in the tumor were positively correlated with the frequencies of CD8⁺ TILs. Together, we demonstrated that Th9 cells infiltrated CRC tumor, could be regulated via the PD-1/PD-L1 pathway, and could contribute the CD8⁺ T cell expansion.

Cytotoxic T-Lymphocyte-Associated Antigen 4 (CTLA-4)- and Programmed Death 1 (PD-1)-Mediated Regulation of Monofunctional and Dual Functional CD4+ and CD8+ T-Cell Responses in a Chronic Helminth Infection

Chronic helminth infections are known to be associated with the modulation of antigen-specific T-cell responses. Strongyloides stercoralis infection is characterized by the downmodulation of antigen-specific Th1 and Th17 responses and the upregulation of Th2 and Th9 responses. Immune homeostasis is partially maintained by negative regulators of T-cell activation, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed death 1 (PD-1), which dampen effector responses during chronic infections. However, their roles in S. stercoralis infection are yet to be defined. Therefore, we sought to determine the role of CTLA-4 and PD-1 in regulating CD4⁺ and CD8⁺ T-cell responses and examined the frequencies of monofunctional and dual functional Th1/T cytotoxic type 1 (Tc1), Th17/Tc17, Th2/Tc2, and Th9/Tc9 cells in S. stercoralis infection in 15 infected individuals stimulated with parasite antigen following CTLA-4 or PD-1 blockade. Our data reveal that CTLA-4 or PD-1 blockade results in significantly enhanced frequencies of monofunctional and dual functional Th1/Tc1 and Th17/Tc17 cells and, in contrast, diminishes the frequencies of monofunctional and dual functional Th2/Tc2 and Th9/Tc9 cells with parasite antigen stimulation in whole-blood cultures. Thus, we demonstrate that CTLA-4 and PD-1 limit the induction of particular T-cell subsets in S. stercoralis infection, which suggests the importance of CTLA-4 and PD-1 in immune modulation in a chronic helminth infection.

Hepatitis B Virus X Protein-Induced RORγ Expression to Promote the Migration and Proliferation of Hepatocellular Carcinoma

Aberrant expression of RORγ is implicated in cancer development. A previous study identified that RORγ functions as a tumor promoter to drive hepatocellular carcinoma (HCC) growth. However, its expression and significance in HCC remain unclear. The central finding of this work is that RORγ was overexpressed in HCC due to its dysfunction of promoter methylation, and hepatitis B virus X protein (HBx) can remarkably induce the expression of RORγ in hepatocellular carcinoma through enhancing the transcriptional function. Also, the HBx-induced RORγ could promote the migration and proliferation of hepatoma cells. Hence, these results suggest that RORγ was an important regulator in HCC, and our finding provides new insights into the significance of RORγ in HCC.

Progression or suppression: Two sides of the innate lymphoid cells in cancer

Innate lymphoid cells (ILCs) as key players in innate immunity have been shown to be significantly associated with inflammation, lymphoid neogenesis, tissue remodeling, mucosal immunity and lately have been considered a remarkable nominee for either tumor-promoting or tumor-inhibiting functions. This dual role of ILCs, which is driven by intrinsic and extrinsic factors like plasticity of ILCs and the tumor microenvironment, respectively, has aroused interest in ILCs subsets in past decade. So far, numerous studies in the cancer field have revealed ILCs to be key players in the initiation, progression and inhibition of tumors, therefore providing valuable insights into therapeutic approaches to utilize the immune system against cancer. Herein, the most recent achievements regarding ILCs subsets including new classifications, their transcription factors, markers, cytokine release and mechanisms that led to either progression or inhibition of many tumors have been evaluated. Additionally, the available data regarding ILCs in most prevalent cancers and new therapeutic approaches are summarized.

T-Cell Differentiation to T Helper 9 Phenotype is Elevated by Extremely Low-Frequency Electromagnetic Fields Via Induction of IL-2 Signaling

Owing to the development of information technology and the electronics industry, and the increase in the use of electronic products, an increasing number of people are exposed to electromagnetic fields (EMFs) in daily life. There has been concern about the effects of EMFs on the human body. Th9 cells, which are characterized by the generation of interleukin-(IL-9), are a recently defined subset of T helper (Th) cells. In this study, we investigated the effect of extremely low-frequency (60 Hz) EMFs, such as those generated by household power sources, at 0.8 mT intensity on CD4⁺ T cells. The exposure of CD4⁺ T cells to such EMFs under Th9-polarizing conditions increased IL-9 secretion and gene expression of transcription factors that are important for Th9 development. The expression of GATA3 increased in the early stage, and the phosphorylation of STAT5 and STAT6, which regulate the expression of GATA3, increased. In addition, EMFs increased the expression of IL-2 by the T cells. In conclusion, the differentiation of CD4⁺ T cells to the Th9 phenotype was increased by exposure to extremely low-frequency EMFs, and this appeared to be dependent on the IL-2 signaling pathway. Furthermore, co-cultures of EMF-exposed Th9 cells and mast cells showed an increased expression of mast cell proteases, FcεR1α, and mast cell-derived inflammatory cytokines compared with co-cultures of non-EMF-exposed Th9 cells and mast cells. Our results suggest that EMFs enhance the differentiation of CD4⁺ T cells to the Th9 phenotype, resulting in mast cell activation and inflammation. Bioelectromagnetics. 2019;40:588-601. © 2019 Bioelectromagnetics Society.

Th9 cytokines curb cervical cancer progression and immune evasion

Cervical cancer is one of the most common cancers among women in developing countries. Persistent infection with high-risk human papillomavirus (HPV) is the major determinant for the development of cervical cancer. Role of newly discovered T helper 9 (Th9) cells in cervical cancer pathogenesis is yet unfolded. In this study, we observed a huge infiltration of PU.1⁺ cells and overrepresentation of IL-9R in tissue biopsy specimens of CIN patients in cervical cancer cases. Treatment with Th9 signatory cytokines, IL-9 and IL-21, suppressed proliferation, enhanced apoptosis and stimulated the expression of MHC I and e-cadherin on HeLa cell lines. Th9 thus seems enhance antitumor immune response through T cell cytotoxicity and play crucial role in a controlling malignant cell transformation. Therefore, this study helps in firmer understanding of relevance of Th9 in cervical cancer immunity.

The γc Family of Cytokines: Basic Biology to Therapeutic Ramifications

The common cytokine receptor γ chain, γ_c, is a component of the receptors for interleukin-2 (IL-2), IL-4, IL-7, IL-9, IL-15, and IL-21. Mutation of the gene encoding γ_c results in X-linked severe combined immunodeficiency in humans, and γ_c family cytokines collectively regulate development, proliferation, survival, and differentiation of immune cells. Here, we review the basic biology of these cytokines, highlighting mechanisms of signaling and gene regulation that have provided insights for immunodeficiency, autoimmunity, allergic diseases, and cancer. Moreover, we discuss how studies of this family stimulated the development of JAK3 inhibitors and present an overview of current strategies targeting these pathways in the clinic, including novel antibodies, antagonists, and partial agonists. The diverse roles of these cytokines on a range of immune cells have important therapeutic implications.

Emerging Roles of Th9 Cells as an Anti-tumor Helper T Cells

The newly discovered Th9 cells are the distinct subset of CD4⁺ T helper (Th) cells, which are involved in various pathophysiological conditions of an immune response. In addition to its role in allergic inflammation and elimination of extracellular pathogens, Th9 cells were found to play a key role in inducing anti-tumor immune response. Precisely, the anti-tumor functions of Th9 cells were found to be superior as compared to Th1 and other Th subsets. Th9 cells eliminate tumors via activating innate and adaptive immune cells, and in particular, generating a profound effector cytotoxic T lymphocyte (CTL) response against neo antigens. In addition, it was proposed that Th9 cells were found to induce effector functions of innate cells like dendritic cells, mast cells and NK cells, which further promote a robust anti-tumor immune response. In this review, we highlight the recent advances in differentiation and functions of Th9 cells in anti-tumor immunity.

The dichotomous function of interleukin-9 in cancer diseases

The pleiotropic function of the cytokine IL-9 is so far described in many inflammation processes and autoimmune diseases. But its role in cancer immunology is rather diverse as it can have a pro-tumorigenic function as well as anti-tumorigenic characteristics. In various disease models of cancer, this cytokine is involved in different signaling pathways triggering the expression of proteins involved in cell growth, migration, and transformation or repressing cells from the adaptive immune system to reject tumor growth. Additionally, there are even therapeutic approaches for IL-9 in cancer development. This review will give an overview of the various roles of IL-9 in different immune organs and cells and provide an insight in the current state of research in the IL-9-dependent cancer area.

IL-9-producing CD8+ T cells represent a distinctive subset with different transcriptional characteristics from conventional CD8+ T cells, and partially infiltrate breast tumors

Accumulating evidence suggests that IL-9 and IL-9-producing cells exert various roles in antitumor immunity. Our study examined the IL-9 production in CD8⁺ T cells from breast cancer patients as compared to healthy controls. IL-9 secretion was undetectable in CD8⁺ T cells ex vivo, but could be readily detected following anti-TCR or PMA + ionomycin stimulation, and was higher in breast cancer patients than in healthy controls. The capacity to express IL-9 was not universal to all CD8⁺ T cells, but was favored in IL-9R^high CD8⁺ T cells, which were also present in breast cancer patients at significantly higher frequency than in healthy controls. Interestingly, exogenous IL-9 could significantly increase the expression of both IL-9 and IL-9R in IL-9R^high, but not IL-9R^low, CD8⁺ T cells. IL-9R^high CD8⁺ T cells ex vivo presented lower expression of KLRG-1, PD-1, and Tim-3 than IL-9R^low CD8⁺ T cells. Additionally, IL-9R^high CD8⁺ T cells following anti-TCR and PMA + ionomycin stimulation presented higher IL-2 and IL-17 expression, and lower IFN-γ expression, than IL-9R^low CD8⁺ T cells. IL-9-expressing CD8⁺ T cells could be found in some, but not all, resected breast tumors. IL-9R expression, on the other hand, was readily present in CD8⁺ T cells, but with high variability from patient to patient. Patients with high intratumoral IL-9 expression also tended to present high IL-9R expression. Together, these data demonstrate that a transcriptionally distinctive IL-9-producing CD8⁺ T cell subset was elevated in breast cancer patients and could be found inside the tumor, with higher capacity to produce IL-2 and IL-17 and lower expression of inhibitory receptors.

Functions of Group 2 Innate Lymphoid Cells in Tumor Microenvironment

Innate lymphoid cells (ILCs), defined as a heterogeneous population of lymphocytes, have received much attention over recent years. They can be categorized into three subsets according to the expression profiles of transcription factors and differing levels of cytokine production. These cells are widely distributed in human organs and tissues, especially in mucosal tissue. The ILCs are involved in various physiological and pathological processes, including inflammation, worm expulsion, autoimmune disease and tumor progression, many of which have been investigated and clarified in recent studies. In the tumor microenvironment, group 2 innate lymphoid cells (ILC2s) have been proved to be able to either promote or inhibit tumor progression by producing different cytokines, recruiting diverse types of immune cells, expressing immunosuppressive molecules and by regulating the expression of certain inflammatory factors. This review summarizes recent research progress on the immunomodulatory functions of ILC2s in the tumor microenvironment and puts forward some perspectives for future study.

Fas signaling-mediated TH9 cell differentiation favors bowel inflammation and antitumor functions

Fas induces apoptosis in activated T cell to maintain immune homeostasis, but the effects of non-apoptotic Fas signaling on T cells remain unclear. Here we show that Fas promotes T_H9 cell differentiation by activating NF-κB via Ca²⁺-dependent PKC-β activation. In addition, PKC-β also phosphorylates p38 to inactivate NFAT1 and reduce NFAT1-NF-κB synergy to promote the Fas^-induced T_H9 transcription program. Fas ligation exacerbates inflammatory bowel disease by increasing T_H9 cell differentiation, and promotes antitumor activity in p38 inhibitor-treated T_H9 cells. Furthermore, low-dose p38 inhibitor suppresses tumor growth without inducing systemic adverse effects. In patients with tumor, relatively high T_H9 cell numbers are associated with good prognosis. Our study thus implicates Fas in CD4⁺ T cells as a target for inflammatory bowel disease therapy. Furthermore, simultaneous Fas ligation and low-dose p38 inhibition may be an effective approach for T_H9 cell induction and cancer therapy.

Fas signalling induces apoptosis of activated T cells to maintain immune homeostasis. Here the authors show that Fas also induces PKC-β activation to promote NF-κB-mediated T_H9 cell differentiation, while p38 activation by PKC-β antagonizes this effect, thereby supporting a synergy between p38 inhibitor and Fas for T_H9 differentiation.

Potential Mechanisms of T Cell-Mediated and Eosinophil-Independent Bronchial Hyperresponsiveness

Bronchial asthma is a chronic disease characterized by reversible airway obstruction, mucus production, and bronchial hyperresponsiveness (BHR). Although Th2 cell-mediated eosinophilic inflammation is an important disease mechanism in the majority of patients with bronchial asthma, recent studies suggest the possible development of Th2-independent airway inflammation and BHR. These non-Th2 endotype patients seem to consist of multiple subgroups, and often do not respond to inhaled corticosteroids. Therefore, to understand the pathogenesis of asthma, it is important to characterize these non-Th2 subgroups. Recently, we demonstrated that Th9 cells induce eosinophil infiltration and eosinophil-independent BHR, and Th9 cells-mediated BHR may be resistant to glucocorticoid. In this review, we summarize the contribution of several T cell subsets in the development of bronchial asthma and introduce our recent study demonstrating Th9 cell-mediated and eosinophil-independent BHR.

The Dosage of the Derivative of Clostridium Ghonii (DCG) Spores Dictates Whether an IFNγ/IL-9 or a Strong IFNγ Response Is Elicited in TC-1 Tumour Bearing Mice

Background

Anaerobic Clostridial spores (CG) cause significant oncolysis in hypoxic tumour microenvironment and result in tumour regression in both animal models and clinical trials. The immune mediated response plays a critical role in the antitumour effect by the anaerobic spore treatment.

Method

Human papillomavirus 16 E6/E7 transformed TC-1 tumour bearing mice were intravenously administered with low (1 × 10⁸ CFU/kg) or high dosage (3 × 10⁸ CFU/kg) of Derivative Clostridial spore (DCG).

Results

Intravenous administration of the derivative of Clostridial ghonii (DCG) spores leads to both tumour and systemic inflammatory responses characterized by increased IFNγ/IL-9 secreting T cells in the spleen and the tumour. Low numbers of antigen specific T cells (<20/10⁶ spleen cells) in the spleen of the tumour bearing mice are also detected after intravenous DCG delivery. Interestingly, our results showed that a mixed IL-9/IFNγ secreting T cell response was induced when the tumour bearing mice received a low dose of DCG spore (1 × 10⁸ CFU/kg), while a strong IFNγ response was elicited with a high dosage of DCG spore (3 × 10⁸ CFU/kg).

Conclusion

The dosage of DCG spore will determine the types of the DCG induced immune responses.

Deciphering Mechanisms of UVR-Induced Tumoral Immune Checkpoint Regulation against Melanoma

Exposure to solar ultraviolet radiation (UVR) impacts various cellular, genetic, and immunologic responses governing biological and pathophysiologic events including the development of skin cancers. The mechanistic insights into UVR-induced immune tolerance against skin cancers, particularly cutaneous melanoma, have been a great challenge, given the sophisticated regulation of immune checkpoint proteins. A study led by Wang and colleagues has elucidated novel mechanisms of UVR-induced immune suppression, implicated in melanoma immune evasion and progression mediated via upregulation of PD-L1, and reduced CD8+ T-cell-mediated cytotoxicity in HMGB1/TBK1/IRF3/NF-κB-dependent manner. These findings offer new mechanistic insights into UVR-induced melanoma immune evasion and progression.See related article by Wang et al., p. 2909.

ATP Triggers Human Th9 Cell Differentiation via Nitric Oxide-Mediated mTOR-HIF1α Pathway

Interleukin 9 (IL-9)-producing helper T (Th9) cells have a crucial effector function in inducing allergic inflammation, autoimmunity, immunity to extracellular pathogens and anti-tumor immune responses. Although the cytokines that lead to the differentiation of human Th9 cells have been identified, other factors that support the differentiation of Th9 cells have not been identified yet. Here we show that the extracellular ATP (eATP) induces the differentiation of Th9 cells. We further show that eATP induces the production of nitric oxide (NO), which create a feed forward loop in the differentiation of human Th9 cells, as inhibition of purinergic receptor signaling suppressed the generation of human Th9 cells while exogenous NO could rescue generation of Th9 cells even upon inhibition of purinergic receptor signaling. Moreover, we show that ATP promotes mTOR and HIF1α dependent generation of Th9 cells. Our findings thus identify that ATP induced nitric oxide potentiate HIF1α-mediated metabolic pathway that leads to IL-9 induction in Th9 cells. Here we identified that the ATP-NO-mTOR-HIF1α axis is essential for the generation of human Th9 cells and modulation of this axis may lead to therapeutic intervention of Th9-associated disease conditions.

HLA-Class II Artificial Antigen Presenting Cells in CD4+ T Cell-Based Immunotherapy

CD4⁺ T cells differentiate into various T helper subsets characterized by distinct cytokine secreting profiles that confer them effector functions adapted to a variety of infectious or endogenous threats. Regulatory CD4⁺ T cells are another specialized subset that plays a fundamental role in the maintenance of immune tolerance to self-antigens. Manipulating effector or regulatory CD4⁺ T cells responses is a promising immunotherapy strategy for, respectively, chronical viral infections and cancer, or severe autoimmune diseases and transplantation. Adoptive cell therapy (ACT) is an emerging approach that necessitates defining robust and efficient methods for the in vitro expansion of antigen-specific T cells then infused into patients. To address this challenge, artificial antigen presenting cells (AAPCs) have been developed. They constitute a reliable and easily usable platform to stimulate and amplify antigen-specific CD4⁺ T cells. Here, we review the recent advances in understanding the functions of CD4⁺ T cells in immunity and in immune tolerance, and their use for ACT. We also describe the characteristics of different AAPC models and the way to improve their stimulating functions. Finally, we discuss the potential interest of these AAPCs, both as fundamental tools to decipher CD4⁺ T cell responses and as reagents to generate clinical grade antigen-specific CD4⁺ T cells for immunotherapy.

Translation of cancer immunotherapy from the bench to the bedside

The tremendous success of immune checkpoint blockades has revolutionized cancer management. Our increased understanding of the cell types that compose the tumor microenvironment (TME), including those of the innate and adaptive immune system, has helped to shape additional immune modulatory strategies in cancer care. Pre-clinical and clinical investigations targeting novel checkpoint interactions and key pathways that regulate cancer immunity continue to increase rapidly. Various combinatorial drug regimens are being tested in attempt to achieve durable response and survival rates of patients with cancer. This review provides an overview of specific components of the TME, an introduction to novel immune checkpoints, followed by a survey of present day and future combination immune modulatory therapies. The idea that the immune system can recognize and destroy tumor cells was first described in the cancer immunosurveillance hypothesis of Burnet and Thomas. However, early experimental evidence failed to support the concept. It was not until the late 1990s when seminal papers clearly showed the existence of cancer immunosurveillance, leading to the cancer immunoediting hypothesis. In this century, progress in the understanding of negative regulators of the immune response led to the discovery that inhibition of these regulators in patients with cancer could lead to dramatic and durable remissions. Drs. Tasuku Honjo and James P. Allison were awarded the Nobel Prize in 2018 for their pioneering work in this field. We now see rapid advances in cancer immunology and emerging effective therapies revolutionizing cancer care across tumor types in the clinic, while pre-clinical research is moving from a focus on the malignant cells themselves to dissect the highly heterogenic and complex multi-cellular tumor microenvironment (TME).

A role for BATF3 in TH9 differentiation and T-cell-driven mucosal pathologies

T helper 9 (T_H9) cells are important for the development of inflammatory and allergic diseases. The T_H9 transcriptional network converges signals from cytokines and antigen presentation but is incompletely understood. Here, we identified TL1A, a member of the TNF superfamily, as a strong inducer of mouse and human T_H9 differentiation. Mechanistically, TL1A induced the expression of the transcription factors BATF and BATF3 and facilitated their binding to the Il9 promoter leading to enhanced secretion of IL-9. BATF- and BATF3-deficiencies impaired IL-9 secretion under T_H9 and T_H9-TL1A-polarizing conditions. In vivo, using a T-cell transfer model, we demonstrated that TL1A promoted IL-9-dependent, T_H9 cell-induced intestinal and lung inflammation. Neutralizing IL-9 antibodies attenuated TL1A-driven mucosal inflammation. Batf3^-/- T_H9-TL1A cells induced reduced inflammation and cytokine expression in vivo compared to WT cells. Our results demonstrate that TL1A promotes T_H9 cell differentiation and function and define a role for BATF3 in T-cell-driven mucosal inflammation.

Hide and seek: Plasticity of innate lymphoid cells in cancer

The advance of immunotherapies has revolutionized the treatment of cancer patients. Mostly agents modulating the adaptive immune system are currently used. More recently, attempts to stimulate the innate immune system are being promoted for clinical evaluation. Innate lymphoid cells (ILCs) are a highly plastic population of immune cells crucial for tissue homeostasis and the regulation of immune responses and maybe a promising target to improve current cancer immunotherapies. Although we have made significant progress in understanding ILC biology, their impact on tumor development, progression and therapy is controversial. In this review, we discuss the recent advances of ILC function and plasticity in the context of cancer.

Double Positive CD4+CD8+ T Cells Are Enriched in Urological Cancers and Favor T Helper-2 Polarization

The immune system plays a central role in cancer development, showing both anti-tumor and pro-tumor activities depending on the immune cell subsets and the disease context. While CD8 T cells are associated with a favorable outcome in most cancers, only T helper type 1 (Th1) CD4 T cells play a protective role, in contrast to Th2 CD4 T cells. Double positive (DP) CD4⁺CD8⁺ T cells remain understudied, although they were already described in human cancers, with conflicting data regarding their role. Here, we quantified and phenotypically/functionally characterized DP T cells in blood from urological cancer patients. We analyzed blood leukocytes of 24 healthy donors (HD) and 114 patients with urological cancers, including bladder (n = 54), prostate (n = 31), and kidney (n = 29) cancer patients using 10-color flow cytometry. As compared to HD, levels of circulating DP T cells were elevated in all urological cancer patients, which could be attributed to increased frequencies of both CD4^highCD8^low and CD4⁺CD8^high DP T-cell subsets. Of note, most CD4^highCD8^low DP T cells show a CD8αα phenotype, whereas CD4⁺CD8^high cells express both CD8α and CD8β subunits. Functional properties were investigated using ex-vivo generated DP T-cell clones. DP T cells from patients were skewed toward an effector memory phenotype, along with enhanced Th2 cytokine production. Interestingly, both CD8αα and CD8αβ DP T cells were able to trigger Th2 polarization of naïve CD4 T cells, while restraining Th1 induction. Thus, these data highlight a previously unrecognized immunoregulatory mechanism involving DP CD4⁺CD8⁺ T cells in urological cancers.

Innate lymphoid cells: A potential link between microbiota and immune responses against cancer

The adaptive immune system plays a crucial role in anti-tumor surveillance. Enhancement of T cell responses through checkpoint blockade has become a major therapeutic avenue of intervention for several tumors. Because it shapes immune responses and regulates their amplitude and duration, the microbiota has a substantial impact on anti-tumor immunity. Innate lymphoid cells (ILCs) comprise a heterogeneous population of lymphocytes devoid of antigen-specific receptors that mirror T helper cells in their ability to secrete cytokines that activate immune responses. Ongoing studies suggest that ILCs contribute to anti-tumor responses. Moreover, since ILCs are present at barrier surfaces, they are stimulated by the microbiota and, reciprocally, influence the composition of the microbiota by regulating the surface barrier microenvironment. Thus, ILC-microbiota cross-talk may in part underpin the effects of the microbiota on anti-tumor responses. In this article, we review current evidence linking ILCs to cancer and discuss the potential impact of ILC-microbiota cross-talk in anti-tumor immune responses.

NCR- group 3 innate lymphoid cells orchestrate IL-23/IL-17 axis to promote hepatocellular carcinoma development

Background

Innate lymphoid cells (ILCs) are a newly discovered family of immune cells that have similar cytokine-secreting profiles as T helper cell subsets. Although ILCs are critical for host defense against infections and tissue homeostasis, their roles in tumor development are not well established.

Methods

We studied the function of ILC3 cells in the liver for the development of hepatocellular carcinoma (HCC) in murine HCC models using flow cytometry, adoptive transfer, and in vitro functional assays.

Findings

We found that ILC3 lacking the natural cytotoxicity-triggering receptor (NCR⁻ILC3) promoted the development of HCC in response to interleukin 23 (IL-23). IL-23 serum level is elevated in HCC patients and its high expression is associated with poor clinical outcomes. We found that IL-23 could promote tumor development in murine HCC tumor models. IL-23 promoted the expansion of NCR⁻ILC3 and its differentiation from group 1 ILCs (ILC1s). Furthermore, NCR⁻ILC3 initiated IL-17 production upon IL-23 stimulation and directly inhibited CD8⁺ T cell immunity by promoting lymphocyte apoptosis and limiting their proliferation.

Interpretation

Together, our findings suggest that NCR⁻ILC3 initiates the IL-17-rich immunosuppressive tumor microenvironment and promotes the development of HCC, thus may serve as a promising target for future cancer immunotherapy.

Fund

This work was supported by grants from National Natural Science Foundation of China (81471586, 81571556), the Priority Academic Program Development of Jiangsu Higher Education Institutions, the collaborative Innovation Center of Hematology, start-up grant from National University of Singapore, the Cancer Prevention and Research Institute of Texas CPRIT (RR180017), and the National Cancer Institute's Cancer Center Support (Core) Grant CA016672 (to The University of Texas MD Anderson Cancer Center).

The cytokine environment influence on human skin-derived T cells

Skin resident T cells provide immediate immunologic responses at their specific location and play a role in the pathogenesis of skin diseases such as psoriasis. Recently, IL-9-producing T cells were described as a major T-cell subtype present in the skin, but knowledge on the biology and in situ regulation of this T-cell subtype is scarce. Here, we investigated the cytokine influence on skin T cells with focus on IL-9-producing T cells because a better understanding of their biology may identify novel therapeutic approaches. Healthy human skin biopsies were cultured either in the presence of IL-2, IL-4, and TGF-β [T helper (T_h)9-promoting condition (T_h9-PC)] or IL-2 and IL-15 [standard condition (SC)]. Paired analysis of enzymatically isolated skin T cells and emigrated T cells after 4 wk of skin culture showed significant alterations of T-cell phenotypes, cytokine production, and IL-9-producing T-cell frequency. RNA sequencing analysis revealed differentially regulated pathways and identified CXCL8 and CXCL13 as top up-regulated genes in T_h9-PC compared with SC. Functionally supernatant of stimulated skin-derived T cells, CXCL8 and CXCL13 increased neutrophil survival. We report that the cytokine environment alters skin-derived T-cell phenotype and functional properties.-Kienzl, P., Polacek, R., Reithofer, M., Reitermaier, R., Hagenbach, P., Tajpara, P., Vierhapper, M., Gschwandtner, M., Mildner, M. Jahn-Schmid, B., Elbe-Bürger, A. The cytokine environment influence on human skin-derived T cells.

Fueling Cancer Immunotherapy With Common Gamma Chain Cytokines

Adoptive T cell transfer therapy (ACT) using tumor infiltrating lymphocytes or lymphocytes redirected with antigen receptors (CAR or TCR) has revolutionized the field of cancer immunotherapy. Although CAR T cell therapy mediates robust responses in patients with hematological malignancies, this approach has been less effective for treating patients with solid tumors. Additionally, toxicities post T cell infusion highlight the need for safer ACT protocols. Current protocols traditionally expand T lymphocytes isolated from patient tumors or from peripheral blood to large magnitudes in the presence of high dose IL-2 prior to infusion. Unfortunately, this expansion protocol differentiates T cells to a full effector or terminal phenotype in vitro, consequently reducing their long-term survival and antitumor effectiveness in vivo. Post-infusion, T cells face further obstacles limiting their persistence and function within the suppressive tumor microenvironment. Therapeutic manipulation of T cells with common γ chain cytokines, which are critical growth factors for T cells, may be the key to bypass such immunological hurdles. Herein, we discuss the primary functions of the common γ chain cytokines impacting T cell survival and memory and then elaborate on how these distinct cytokines have been used to augment T cell-based cancer immunotherapy.

Differential Influence of IL-9 and IL-17 on Actin Cytoskeleton Regulates the Migration Potential of Human Keratinocytes

T cells mediate skin immune surveillance by secreting specific cytokines and regulate numerous functions of keratinocytes, including migration during homeostasis and disease pathogenesis. Keratinocyte migration is mediated mainly by proteolytic cleavage of the extracellular matrix and/or by cytoskeleton reorganization. However, the cross-talk between T cell cytokines and actomyosin machinery of human primary keratinocytes (HPKs), which is required for cytoskeleton reorganization and subsequent migration, remains poorly examined. In this study, we describe that IL-9 profoundly reduced the actin stress fibers, inhibited contractility, and reduced the cortical stiffness of HPKs, which resulted in inhibition of the migration potential of HPKs in an adhesion- and MMP-independent manner. Similarly, IL-9 inhibited the IFN-γ-induced migration of HPKs by inhibiting the actomyosin machinery (actin stress fibers, contractility, and stiffness). IL-17A increased the actin stress fibers, promoted cellular contractility, and increased proteolytic collagen degradation, resulting in increased migration potential of HPKs. However, IL-9 inhibited the IL-17A-mediated HPKs migration. Mechanistically, IL-9 inhibited the IFN-γ- and IL-17A-induced phosphorylation of myosin L chain in HPKs, which is a major regulator of the actomyosin cytoskeleton. Finally, in addition to HPKs, IL-9 inhibited the migration of A-431 cells (epidermoid carcinoma cells) induced either by IFN-γ or IL-17A. In conclusion, our data demonstrate the influence of T cell cytokines in differentially regulating the actomyosin cytoskeleton and migration potential of human keratinocytes, which may have critical roles in skin homeostasis and pathogenesis of inflammatory diseases as well as skin malignancies.

GM-CSF Promotes Antitumor Immunity by Inducing Th9 Cell Responses

GM-CSF as an adjuvant has been shown to promote antitumor immunity in mice and humans; however, the underlying mechanism of GM-CSF-induced antitumor immunity remains incompletely understood. In this study, we demonstrate that GM-CSF potentiates the efficacy of cancer vaccines through IL9-producing Th (Th9) cells. GM-CSF selectively enhanced Th9 cell differentiation by regulating the COX2-PGE₂ pathway while inhibiting the differentiation of induced regulatory T (iTreg) cells in vitro and in vivo GM-CSF-activated monocyte-derived dendritic cells converted tumor-specific naïve Th cells into Th9 cells, and delayed tumor growth by inducing antitumor CTLs in an IL9-dependent manner. Our findings reveal a mechanism for the adjuvanticity of GM-CSF and provide a rationale for the use of GM-CSF in cancer vaccines.

TNF-α enhances Th9 cell differentiation and antitumor immunity via TNFR2-dependent pathways

Tumor specific Th9 cells are potential effector cells for adoptive therapy of human cancers. TNF family members OX40L, TL1A and GITRL have been shown to promote the induction of Th9 cells and antitumor immunity. However, the role of TNF-α, the prototype of the TNF superfamily cytokines, in Th9 cell differentiation and their antitumor efficacy is not defined. Here, we showed that TNF-α potently promoted naïve CD4+ T cells to differentiate into Th9 cells in vitro. Furthermore, the addition of TNF-α during Th9 cell differentiation increased T cell survival and proliferation. More importantly, the adoptive transfer of TNF-α-treated Th9 cells induced more potent antitumor effects than regular Th9 cells in mouse tumor model. TNF-α signals via two cell surface receptors, TNFR1 and TNFR2. Mechanistic studies revealed that TNF-α drove Th9 cell differentiation through TNFR2 but not TNFR1. In addition, under Th9 polarizing condition, TNF-α activated STAT5 and NF-κB pathways in T cells in a TNFR2-dependent manner. Inhibition of STAT5 and NF-κB pathways by their specific inhibitors impaired TNF-α-induced Th9 cell differentiation. Our results identified TNF-α as a new powerful inducer of Th9 cells and clarified the molecular mechanisms underlying TNF-α-induced Th9 cell differentiation.