Th9 cells: differentiation and disease

Targeting the epigenetic regulation of antitumour immunity

Dysregulation of the epigenome drives aberrant transcriptional programmes that promote cancer onset and progression. Although defective gene regulation often affects oncogenic and tumour-suppressor networks, tumour immunogenicity and immune cells involved in antitumour responses may also be affected by epigenomic alterations. This could have important implications for the development and application of both epigenetic therapies and cancer immunotherapies, and combinations thereof. Here, we review the role of key aberrant epigenetic processes - DNA methylation and post-translational modification of histones - in tumour immunogenicity, as well as the effects of epigenetic modulation on antitumour immune cell function. We emphasize opportunities for small-molecule inhibitors of epigenetic regulators to enhance antitumour immune responses, and discuss the challenges of exploiting the complex interplay between cancer epigenetics and cancer immunology to develop treatment regimens combining epigenetic therapies with immunotherapies.

T Helper (Th) Cell Profiles in Pregnancy and Recurrent Pregnancy Losses: Th1/Th2/Th9/Th17/Th22/Tfh Cells

During pregnancy, various immune effectors and molecules participating in the immune-microenvironment establish specific maternal tolerance toward the semi-allogeneic fetus. Activated maternal immune effectors by the trophoblast antigens, such as T helper (Th), T cytotoxic (Tc), T regulatory (Treg), and B cells, are involved in the regulation of adaptive immunity. Recognition of active signal through the T cell receptors stimulate the differentiation of naive CD3⁺CD4⁺ T cells into specific T cell subsets, such as Th1, Th2, Th9, Th17, Th22, and follicular Th cells (Tfh). Each of these subsets has a significant and distinct role in human pregnancy. Th1 immunity, characterized by immune-inflammatory responses, becomes dominant during the peri-implantation period, and the “controlled” Th1 immunity benefits the invading trophoblasts rather than harm. Quickly after the placental implantation, the early inflammatory Th1 immunity is shifted to the Th2 anti-inflammatory immune responses. The predominant Th2 immunity, which overrules the Th1 immunity at the placental implantation site, protects a fetus by balancing Th1 immunity and accommodate fetal and placental development. Moreover, Treg and Th9 cells regulate local inflammatory immune responses, potentially detrimental to the fetus. Th17 cells induce protective immunity against extracellular microbes during pregnancy. However, excessive Th17 immunity may induce uncontrolled neutrophil infiltration at the maternal-fetal interface. Other Th cell subsets such as Tfh cells, also contribute to pregnancy by setting up favorable humoral immunity during pregnancy. However, dysregulation of Th cell immunity during pregnancy may result in obstetrical complications, such as recurrent pregnancy losses (RPL) and preeclampsia (PE). With this review, we intend to deliver a comprehensive overview of CD4⁺ Th cell subsets, including Th1, Th2, Th9, Th17, Th22, and Tfh cells, in human pregnancy by reviewing their roles in normal and pathological pregnancies.

Granuloma formation and tissue pathology in Schistosoma japonicum versus Schistosoma mansoni infections

Schistosomiasis is the most important helminth disease in the world from a public health perspective. S mansoni and S japonicum account for the majority of global intestinal schistosomiasis cases, and the pathogenesis is widely assumed to be fundamentally similar. However, the majority of research on schistosomiasis has been carried out on S mansoni and comparisons between the two species are rarely made. Here, we will discuss aspects of both older and recent literature where such comparisons have been made, with a particular focus on the pathological agent, the host granulomatous response to the egg. Major differences between the two species are apparent in features such as egg production patterns and cellular infiltration; however, it is also clear that even subtle differences in the cascade of various cytokines and chemokines contribute to the different levels of pathology observed between these two main species of intestinal schistosomiasis. A better understanding of such differences at species level will be vital when it comes to the development of new treatment strategies and vaccines.

Positive effect of curcumin on experimental peridontitis via suppression of IL-1-beta and IL-6 expression level

This study examined the effect of curcumin on T-helper (Th17) and T-regulatory (Treg) cells regarding the mRNA of cytokines/mediators in the gingiva. Thirty-five male albino Wistar rats were divided into four groups: Group 1: periodontitis (n = 9); Group 2: periodontitis with curcumin treatment (n = 8); Group 3: periodontally healthy with curcumin treatment (n = 10); and Group 4: periodontally healthy (n = 8). Curcumin was administered via oral gavage (30 mg/kg/day) for a total of 15 days. The gingival tissues were investigated regarding mRNA expressions of Th17/Treg cytokines with qRT-PCR. The distributional properties of the data were evaluated using the Anderson-Darling normality test. Kruskal-Wallis and Mann-Whitney U tests were employed for multiple group comparisons. Partial least squares regression discriminant analysis (PLS-DA) was used to evaluate the degree of contribution of each mRNA to the separation of treatment groups. When the periodontitis groups were compared, curcumin treatment resulted in lower IL-1β (Group 2 median: 0.002, Group 1 median: 0.12) and IL-6 (Group 2 median: 0.031, Group 1 median: 0.078) and higher IL-17 (Group 2 median: 1.07, Group 1 median: 0.583) relative mRNA expression in Group 2 than in Group 1 (p < 0.001). Group 3 also had higher IL-10 relative expression (median: 0.067) than Groups 1 and 4 (median: 0.028, 0.007, respectively. p < 0.001). These results indicate that curcumin might be a promising agent for the prevention and/or treatment of periodontal diseases due to its decreasing effect on IL-1β and IL-6 mRNA expression.

T cell subsets and functions in atherosclerosis

Atherosclerosis is a chronic inflammatory disease of the arterial wall and the primary underlying cause of cardiovascular disease. Data from in vivo imaging, cell-lineage tracing and knockout studies in mice, as well as clinical interventional studies and advanced mRNA sequencing techniques, have drawn attention to the role of T cells as critical drivers and modifiers of the pathogenesis of atherosclerosis. CD4+ T cells are commonly found in atherosclerotic plaques. A large body of evidence indicates that T helper 1 (TH1) cells have pro-atherogenic roles and regulatory T (Treg) cells have anti-atherogenic roles. However, Treg cells can become pro-atherogenic. The roles in atherosclerosis of other TH cell subsets such as TH2, TH9, TH17, TH22, follicular helper T cells and CD28null T cells, as well as other T cell subsets including CD8+ T cells and γδ T cells, are less well understood. Moreover, some T cells seem to have both pro-atherogenic and anti-atherogenic functions. In this Review, we summarize the knowledge on T cell subsets, their functions in atherosclerosis and the process of T cell homing to atherosclerotic plaques. Much of our understanding of the roles of T cells in atherosclerosis is based on findings from experimental models. Translating these findings into human disease is challenging but much needed. T cells and their specific cytokines are attractive targets for developing new preventive and therapeutic approaches including potential T cell-related therapies for atherosclerosis.

CD4+ T helper 17 cell response of aged mice promotes prostate cancer cell migration and invasion

BACKGROUND

Aging is the most important risk factor for prostate cancer (PCa), but how age contributes to PCa is poorly understood. Aging is characterized by low-grade systemic inflammation (i.e., inflammaging) that is often attributed to the progressive activation of immune cells over time, which may play an important role in prostate carcinogenesis. Th17 response is elevated in aging humans and mice, but it remains unknown whether it is increased in prostate tissue or contributes to prostate carcinogenesis during aging. In this study, we aimed to determine the role of age-related Th17 response in PCa cell growth, migration, and invasion.

METHODS

C57BL/6J (B6) mouse was used as an aging animal model and the prostate histopathology during aging was analyzed. Splenic CD4⁺ T cells were isolated from young (16-20 weeks old) and aged (96-104 weeks old) mice, and cultured in the presence of plate-bound anti-CD3/anti-CD28, with or without Th17 differentiation conditions. The cells were collected and used for subsequent flow cytometry or quantitative reverse transcription polymerase chain reaction. The supernatant was collected and used to treat PCa cell lines. The treated PCa cells were analyzed for cell viability, migration, invasion, and nuclear factor kappa B (NF-κB) signaling.

RESULTS

Aged mice had enlarged prostate glands and increased morphological alterations, with not only increased inflammatory cell infiltration but also increased Th17 cytokines in prostate tissue, compared to young mice. Naïve CD4⁺ T cells from aged mice differentiated increased interleukin (IL)-17-expressing cells. CD4⁺ T cells from aged mice spleen had increased Th17 cells, Th17 cytokines and Th17/Treg ratio compared to young mice. Factors secreted from aged CD4⁺ T cells, especially from ex vivo differentiated Th17 cells, not only promoted PCa cell viability, migration, and invasion but also activated the NF-κB signaling in PCa cells compared to young mice.

CONCLUSIONS

These results indicate that age-related CD4⁺ T cells, especially Th17 cells-secreted factors have the potential to contribute to prostate carcinogenesis. Our work could prompt further research using autochthonous PCa mouse models at different ages to elucidate the functional role of Th17 response in prostate carcinogenesis during aging.

T Cells in Fibrosis and Fibrotic Diseases

Fibrosis is the extensive deposition of fibrous connective tissue, and it is characterized by the accumulation of collagen and other extracellular matrix (ECM) components. Fibrosis is essential for wound healing and tissue repair in response to a variety of triggers, which include infection, inflammation, autoimmune disorder, degenerative disease, tumor, and injury. Fibrotic remodeling in various diseases, such as liver cirrhosis, pulmonary fibrosis, renal interstitial fibrosis, myocardial infarction, systemic sclerosis (SSc), and graft-versus-host disease (GVHD), can impair organ function, causing high morbidity and mortality. Both innate and adaptive immunity are involved in fibrogenesis. Although the roles of macrophages in fibrogenesis have been studied for many years, the underlying mechanisms concerning the manner in which T cells regulate fibrosis are not completely understood. The T cell receptor (TCR) engages the antigen and shapes the repertoire of antigen-specific T cells. Based on the divergent expression of surface molecules and cell functions, T cells are subdivided into natural killer T (NKT) cells, γδ T cells, CD8⁺ cytotoxic T lymphocytes (CTL), regulatory T (Treg) cells, T follicular regulatory (Tfr) cells, and T helper cells, including Th1, Th2, Th9, Th17, Th22, and T follicular helper (Tfh) cells. In this review, we summarize the pro-fibrotic or anti-fibrotic roles and distinct mechanisms of different T cell subsets. On reviewing the literature, we conclude that the T cell regulations are commonly disease-specific and tissue-specific. Finally, we provide perspectives on microbiota, viral infection, and metabolism, and discuss the current advancements of technologies for identifying novel targets and developing immunotherapies for intervention in fibrosis and fibrotic diseases.

Th9 Cells in Peripheral Blood Increased in Patients with Immune-Related Pancytopenia

Background

Immune-related pancytopenia (IRP) is a kind of autoimmune disease mediated by autoantibodies in bone marrow. T helper 9 (Th9) cell is a new subset of T cell discovered recently, which mainly expresses cytokine interleukin-9 (IL-9) to exert immune function. Th9 cells are associated with a variety of inflammatory diseases, but the role of Th9 cells in IRP remains unclear.

Methods

Fifty patients with IRP and 20 healthy controls were enrolled. The percentage of Th9 cells was detected by flow cytometry (FCM) and ELISA. CD4⁺ lymphocytes were sorted by magnetic beads, and the mRNA expression levels of Th9 cells related transcription factors PU.1 and BATF were detected by RT-PCR.

Results

The percentage of Th9 cells in CD3⁺CD4⁺ cells was 2.73 ± 1.96% in the untreated group, which was significantly higher than those in the remission group (1.21 ± 0.86%) (p < 0.01) and the control group (0.68 ± 0.40%) (p < 0.001). And that in the remission group was significantly higher than that in the control group (p < 0.05). The level of IL-9 in the untreated group was 183.91 ± 112.42 pg/mL, which was significantly higher than that in the remission group (105.96 ± 64.79 pg/mL) (p < 0.01) and control group (56.03 ± 14.49 pg/mL) (p < 0.001). That in the remission group was also significantly higher than that in the control group (p < 0.01). They were negatively correlated with hemoglobin, red blood cell, white blood cell, and platelet counts and positively correlated with the percentage of CD19⁺B cells and CD5⁺CD19⁺/CD19⁺B cells, respectively. The mRNA expression levels of PU.1 and BATF in IRP patients were higher than those in controls (p < 0.05).

Conclusions

The percentage of Th9 cells in the peripheral blood and the level of IL-9 in the serum of patients with IRP were increased, which was related to the severity of the disease.

Expression Efficiency of Multiple Il9 Reporter Alleles Is Determined by Cell Lineage

Generation of allelic gene reporter mice has provided a powerful tool to study gene function in vivo. In conjunction with imaging technologies, reporter mouse models facilitate studies of cell lineage tracing, live cell imaging, and gene expression in the context of diseases. Although there are several advantages to using reporter mice, caution is important to ensure the fidelity of the reporter protein representing the gene of interest. In this study, we compared the efficiency of two Il9 reporter strains Il9^citrine and Il9^GFP in representing IL-9-producing CD4⁺ T_H9 cells. Although both alleles show high specificity in IL-9-expressing populations, we observed that the Il9^GFP allele visualized a much larger proportion of the IL-9-producing cells in culture than the Il9^citrine reporter allele. In defining the mechanistic basis for these differences, chromatin immunoprecipitation and chromatin accessibility assay showed that the Il9^citrine allele was transcriptionally less active in T_H9 cells compared with the wild-type allele. The Il9^citrine allele also only captured a fraction of IL-9-expressing bone marrow-derived mast cells. In contrast, the Il9 ^citrine reporter detected Il9 expression in type 2 innate lymphoid cells at a greater percentage than could be identified by IL-9 intracellular cytokine staining. Taken together, our findings demonstrate that the accuracy of IL-9 reporter mouse models may vary with the cell type being examined. These studies demonstrate the importance of choosing appropriate reporter mouse models that are optimal for detecting the cell type of interest as well as the accuracy of conclusions.

Comparative Analysis of Cytokines of Tumor Cell Lines, Malignant and Benign Effusions Around Breast Implants

BACKGROUND

More than 700 women have developed an anaplastic large T cell lymphoma (ALCL) surrounding textured surface breast implants, termed breast implant-associated ALCL (BIA-ALCL). Most patients with BIA-ALCL present with an accumulation of fluid (delayed seroma) around the implant. However, benign seromas without malignant cells complicating scar contracture, implant rupture, trauma, infection, and other causes are more common. For proper patient management and to avoid unnecessary surgery, a simple diagnostic test to identify malignant seromas is desirable.

OBJECTIVES

The aim of this study was to develop an ancillary test for the diagnosis of malignant seromas and to gain insight into the nature of the malignant cells and their microenvironment.

METHODS

We employed an immunologic assay on only 50 µL of aspirated seroma fluid. The assay measures 13 cytokines simultaneously by flow cytometry. To establish a baseline for clinical studies we measured cytokines secreted by BIA-ALCL and cutaneous ALCL lines.

RESULTS

Our study of cell line culture supernatants, and 8 malignant compared with 9 benign seromas indicates that interleukin 9 (IL-9), IL-10, IL-13, IL-22, and/or interferon γ concentrations >1000 pg/mL distinguish malignant seromas from benign seromas. IL-6, known to be a driver of malignant cells, is also elevated in benign seromas and does not distinguish them from malignant seromas.

CONCLUSIONS

The cytokine assay introduced in this study can be used together with levels of soluble CD30 to identify malignant seromas. Validation of these findings in a larger prospective patient cohort is warranted. The unique pattern of cytokine expression in malignant effusions surrounding breast implants gives further insight into the pathogenesis and cells of origin of BIA-ALCL.

Level of Evidence: 5.

The effects of advanced maternal age on T-cell subsets at the maternal-fetal interface prior to term labor and in the offspring: a mouse study

Women who conceive at 35 years of age or older, commonly known as advanced maternal age, have a higher risk of facing parturition complications and their children have an increased risk of developing diseases later in life. However, the immunological mechanisms underlying these pathological processes have yet to be established. To fill this gap in knowledge, using a murine model and immunophenotyping, we determined the effect of advanced maternal age on the main cellular branch of adaptive immunity, T cells, at the maternal-fetal interface and in the offspring. We report that advanced maternal age impaired the process of labor at term, inducing dystocia and delaying the timing of delivery. Advanced maternal age diminished the number of specific proinflammatory T-cell subsets [T helper type 1 (Th1): CD4⁺ IFN-γ⁺ , CD8⁺ IFN-γ⁺ and Th9: CD4⁺ IL-9⁺ ], as well as CD4⁺ regulatory T cells (CD4⁺ CD25⁺ FoxP3⁺ T cells), at the maternal-fetal interface prior to term labor. Advanced maternal age also altered fetal growth and survival of the offspring in early life. In addition, infants born to advanced-age mothers had alterations in the T-cell repertoire but not in CD71⁺ erythroid cells (CD3^- CD71⁺ TER119⁺ cells). This study provides insight into the immune alterations observed at the maternal-fetal interface of advanced-age mothers and their offspring.

The Regulatory Effects of mTOR Complexes in the Differentiation and Function of CD4+ T Cell Subsets

T cells are an important part of the adaptive immune system and play critical roles in the elimination of various pathogens. T cells could differentiate into distinct cellular subsets under different extracellular signals and then play different roles in maintaining host homeostasis and defense. The mechanistic target of rapamycin (mTOR) is a conserved intracellular serine/threonine kinase which belongs to the phosphoinositide 3-kinase- (PI3K-) related kinase family. The mTOR signaling pathway is closely involved in a variety of cell biological processes, including cell growth and cell metabolism, by senses and integrates various environmental cues. Recent studies showed that mTOR including mTORC1 and mTORC2 is closely involved in the development of T cell subpopulations such as Th1, Th2, Th9, Th17, follicular helper T cells (Tfh), and Treg cells through distinctive pathways. We herein mainly focused on the recent progress in understanding the roles of mTOR in regulating the development and differentiation of CD4⁺ T cell subsets.

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.

CD4+ T cell phenotypes in the pathogenesis of immune thrombocytopenia

Immune thrombocytopenia (ITP) is an autoimmune disorder characterized by low platelet counts due to enhanced platelet clearance and compromised production. Traditionally, ITP was regarded a B cell mediated disorder as anti-platelet antibodies are detected in most patients. The very nature of self-antigens, evident processes of isotype switching and the affinity maturation of anti-platelet antibodies indicate that B cells in order to mount anti-platelet immune response require assistance of auto-reactive CD4⁺ T cells. For a long time, ITP pathogenesis has been exclusively reviewed through the prism of the disturbed balance between Th1 and Th2 subsets of CD4⁺ T cells, however, more recently new subsets of these cells have been described including Th17, Th9, Th22, T follicular helper and regulatory T cells. In this paper, we review the current understanding of the role and immunological mechanisms by which CD4⁺ T cells contribute to the pathogenesis of ITP.

T Lymphocyte-Mediated Liver Immunopathology of Schistosomiasis

The parasitic worms, Schistosoma mansoni and Schistosoma japonicum, reside in the mesenteric veins, where they release eggs that induce a dramatic granulomatous response in the liver and intestines. Subsequently, infection may further develop into significant fibrosis and portal hypertension. Over the past several years, uncovering the mechanism of immunopathology in schistosomiasis has become a major research objective. It is known that T lymphocytes, especially CD4⁺ T cells, are essential for immune responses against Schistosoma species. However, obtaining a clear understanding of how T lymphocytes regulate the pathological process is proving to be a daunting challenge. To date, CD4⁺ T cell subsets have been classified into several distinct T helper (Th) phenotypes including Th1, Th2, Th17, T follicular helper cells (Tfh), Th9, and regulatory T cells (Tregs). In the case of schistosomiasis, the granulomatous inflammation and the chronic liver pathology are critically regulated by the Th1/Th2 responses. Animal studies suggest that there is a moderate Th1 response to parasite antigens during the acute stage, but then, egg-derived antigens induce a sustained and dominant Th2 response that mediates granuloma formation and liver fibrosis. In addition, the newly discovered Th17 cells also play a critical role in the hepatic immunopathology of schistosomiasis. Within the liver, Tregs are recruited to hepatic granulomas and exert an immunosuppressive role to limit the granulomatous inflammation and fibrosis. Moreover, recent studies have shown that Tfh and Th9 cells might also promote liver granulomas and fibrogenesis in the murine schistosomiasis. Thus, during infection, T-cell subsets undergo complicated cross-talk with antigen presenting cells that then defines their various roles in the local microenvironment for regulating the pathological progression of schistosomiasis. This current review summarizes a vast body of literature to elucidate the contribution of T lymphocytes and their associated cytokines in the immunopathology of schistosomiasis.

Anaphylatoxins enhance Th9 cell recruitment via the CCL20-CCR6 axis in IgA nephropathy

BACKGROUND

CD4⁺ T cells are involved in the pathogenesis of immunoglobulin A nephropathy (IgAN); T helper (Th) 1, Th17 and Th22 cells promote the occurrence and amplification of inflammatory reactions, while regulatory T (Treg) cells produce the opposite effects. However, whether Th9 cells, a subset of CD4⁺ T cells, participate in IgAN development is still unknown.

METHODS

Human peripheral blood mononuclear cells (PBMCs) were isolated from IgAN patients for Th9 cells detection by flow cytometry. Wild-type (WT) mouse was used to establish an IgAN mouse model while C3aR and C5aR inhibitor treated IgAN mouse. Kidney disease and function was assessed by histology and albumin-to-creatinine ratio. C3aR and C5aR expression was examined by immunohistochemical (IHC) assay. Th9 cell proportions in the blood of IgAN mouse was detected. C3a, C5a and interleukin (IL)-9 levels were tested by ELISA. Moreover, co-culture system between human mesangial cells (HMCs) and CD4⁺ T cells were constructed with or without C3a, C5a and anti-CCL20 mAb stimulation for transwell assay to examine Th9 cell chemotaxis.

RESULTS

We observed the numbers of Th9 cell and the levels of IL-9 were increased in IgAN patients and IgAN mice. Furthermore, C3a and C5a level in serum and kidney, C3aR and C5aR expression was increased in IgAN mice compared to WT mice. Most interestingly, C3aR and C5aR inhibitor could reduce kidney damage, Th9 cell numbers and IL-9 levels. We also observed that C3a and C5a enhanced CCL20 production in HMCs. Notably, C3a and C5a also increased the recruitment of Th9 cells and IL-9 levels by HMCs through enhancing the CCL20-CCR6 pathway.

CONCLUSIONS

Our results support that C3a and C5a increase the production of CCL20 by HMCs and consequently augment Th9 cell recruitment and IL-9 levels, resulting in IgAN exacerbation.

Significance of TC9 and TH9 in Helicobacter pylori-induced gastritis

BACKGROUND

H pylori plays a critical role in the development of stomach cancer, especially in people affected by the bacteria at an early stage of life. Th9 cells and IL-9 play major roles in immune responses against various infections. IL-9 is influential in chronic or acute inflammation of the mucosa.

AIM

This study seeks to investigate the possible functions of Tc9, Th9 cells, and IL-9 level in patients with inflammation due to H pylori infection.

METHODS

Eighty-three patients with dyspepsia symptoms and twenty normal subjects with no sign and symptoms of dyspepsia were recruited. Frequencies of T-cell subsets were determined by flow cytometry. Levels of cytokines IL-9 family in the sera and supernatants of antigen-activated PBMCs patients were measured by ELISA and flow cytometry.

RESULTS

The participants included 56 females and 47 males with a mean age of 39.2 ± 15.3 years. We assigned the infected group into peptic ulcer and gastritis (chronic active and chronic). Frequencies of Tc9, Th17, Tc17, Th17/9, and Tc17/9 increased significantly in the peptic ulcer, chronic active, and chronic gastritis, compared with the uninfected and healthy control groups. A significant increase was seen in IL-9, IL-4, and IL-23 in the chronic active gastritis. Further observed was a significant increase in IL-21 and a decrease in IL-10 in the infected groups.

CONCLUSION

The results revealed that increased Tc9, Th17/9, and Tc17/9 cells appear to be influential in the progression and severity of H pylori infection. Also, increased IL-9 and IL-4 levels and Tc9, Tc17/9, and Th17/9 were seen in chronic active gastritis patients. These findings may provide useful information for a therapeutic targeting of chronic active H pylori infections.

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.

Galectin Domain Containing Protein from Haemonchus contortus Modulates the Immune Functions of Goat PBMCs and Regulates CD4+ T-Helper Cells In Vitro

Galectins are glycan-binding proteins that are widely expressed and distributed in mammalian tissues as well as cells of innate and adaptive immune responses. CD4+ T-helper cells differentiate into effector subsets in response to cytokines. T helper 9 cells are one of the recently described subsets of effector T cells that are relatively new and less studied. In this study, galectin domain containing protein from Haemonchus contortus (Hc-GDC) was cloned, expressed in pET32a, and immunoblotting was performed. Localization of recombinant (r)Hc-GDC on outer and inner surface of H. contortus worm and binding with goat Peripheral Blood Mononuclear cells (PBMCs) were performed using immunofluorescence assay. Moreover, effects of rHc-GDC on proliferation, apoptosis, cell migration, and the nitric oxide production in goat PBMCs were evaluated. Furthermore, modulatory effects of rHc-GDC on production of Th1, Th2, and Th9 cells were evaluated by flowcytometry and on interferon gamma, interleukin (IL)-4 and IL-9 were evaluated by quantitative real-time polymerase chain reaction. The results demonstrated that rHc-GDC was successfully cloned, expressed in expression vector as well as in the gut surface of adult H. contortus worm and successful binding with PBMCs surface were observed. Immunoblotting results revealed that rHc-GDC is an important active protein of H. contortus excretory and secretory products. Moreover, the interaction of rHc-GDC with host cells increased the production of Th2, Th9 cells, IL4, IL-9, PBMC proliferation, nitric oxide, and cell migration. No effects of rHc-GDC were observed on PMBC apoptosis, production of Th1 cells, and secretions of IFN- and IL-10 cytokines. These findings indicate that recombinant GDC protein from H. contortus modulates the immune functions of goat PBMCs and has the potential to enhance protective immunity by inducing T helper-9-derived IL-9 in vitro.

Crosstalk between T Helper Cell Subsets and Their Roles in Immunopathogenesis and Outcome of Polytrauma Patients

Purpose

One of the leading causes of morbidity and early-age mortality across the globe is trauma. It disrupts immune system homeostasis and intensely affects the innate and adaptive immune responses, predisposing patients to posttrauma complications and poor outcomes. Most of the studies on posttrauma cellular immune response have been centered on the T helper-1-T helper-2 imbalances after trauma. This study was conducted to understand the role of circulating novel T helper cells in the acute posttraumatic period and clinical outcome of trauma patients.

Materials and methods

Signature cytokines and transcription factors of circulating Th (T helper)-9, Th-17, Th-22, and regulatory T helper cells were studied using flowcytometry along with serum biomarkers in 49 patients with polytraumatic injuries admitted to a tertiary care hospital. The patients were followed up until their outcome. The results were correlated with their clinical outcomes.

Results

In patients who died, higher nTreg, iTreg, Tr1 (early-phase), and higher IRF4+Th-9, IL17+ Th-17, and RORγT+ Th-17 (mid-phase) were seen. However, by the late phase, only RORγT+ Th-17 remained higher. Serum IL-6 and PCT were found to be consistently higher. In survivors, higher Th-3 (early phase), Th-22 (mid-phase), and IRF4+Th-9, IL17+ Th-17, nTreg, Th-3 (late phase) were observed to have played a protective role. Serum IL-2, IL-4, IL-17A and IL-22 were significantly higher in survivors.

Conclusion

Different T helper subsets were observed to be playing pathogenic and protective roles in different phases of trauma and could be used for early prognostication and make way for noninvasive management of critically injured trauma patients by immunomodulation.

How to cite this article

Khurana S, Bhardwaj N, Kumar S, Sagar S, Pal R, Soni KD, et al. Crosstalk between T Helper Cell Subsets and Their Roles in Immunopathogenesis and Outcome of Polytrauma Patients. Indian J Crit Care Med 2020;24(11):1037–1044.

IL-9 and Mast Cells Are Key Players of Candida albicans Commensalism and Pathogenesis in the Gut

Candida albicans is implicated in intestinal diseases. Identifying host signatures that discriminate between the pathogenic versus commensal nature of this human commensal is clinically relevant. In the present study, we identify IL-9 and mast cells (MCs) as key players of Candida commensalism and pathogenicity. By inducing TGF-β in stromal MCs, IL-9 pivotally contributes to mucosal immune tolerance via the indoleamine 2,3-dioxygenase enzyme. However, Candida-driven IL-9 and mucosal MCs also contribute to barrier function loss, dissemination, and inflammation in experimental leaky gut models and are upregulated in patients with celiac disease. Inflammatory dysbiosis occurs with IL-9 and MC deficiency, indicating that the activity of IL-9 and MCs may go beyond host immunity to include regulation of the microbiota. Thus, the output of the IL-9/MC axis is highly contextual during Candida colonization and reveals how host immunity and the microbiota finely tune Candida behavior in the gut.

•

IL-9/IL-9R signaling affects MC function in mucosal candidiasis

•

IL-9 and mucosal MCs contribute to barrier function loss in leaky gut models

•

IL-9 and stromal MCs induce local protective tolerance in infection via IDO1

•

IL-9 and mucosal MCs expand and IDO1 decreases in human celiac disease

A Comprehensive Review and Update on the Pathogenesis of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a chronic and life-threating inflammatory disease of gastroenteric tissue characterized by episodes of intestinal inflammation. The pathogenesis of IBD is complex. Recent studies have greatly improved our knowledge of the pathophysiology of IBD, leading to great advances in the treatment as well as diagnosis of IBD. In this review, we have systemically reviewed the pathogenesis of IBD and highlighted recent advances in host genetic factors, gut microbiota, and environmental factors and, especially, in abnormal innate and adaptive immune responses and their interactions, which may hold the keys to identify novel predictive or prognostic biomarkers and develop new therapies.

Resolution of allergic asthma

Allergic asthma is an inflammatory disease of the airways characterized by recurrent episodes of wheezing and bronchoconstriction. Chronic inflammation may finally lead to structural damage followed by airway remodeling. Various studies in recent years contributed to unravel important aspects of the immunopathogenesis of asthma and adapted new pharmaceutical developments. Here, I consider some novel insights into the immunopathogenesis of asthma and the protective and pathogenic roles of some innate and adaptive immune cells as well as the function of soluble mediators such as cytokines. Particular attention will be given to new concepts on resolution of chronic airway inflammation for prevention of airway structural damage.

TH9, TH17, and TH22 Cell Subsets and Their Main Cytokine Products in the Pathogenesis of Colorectal Cancer

In recent years, several newly identified T helper (T_H) cell subsets, such as T_H9, T_H17, and T_H22 cells, and their respective cytokine products, IL-9, IL-17, and IL-22, have been reported to play critical roles in the development of chronic inflammation in the colorectum. Since chronic inflammation is a potent driving force for the development of human colorectal cancer (CRC), the contributions of T_H9/IL-9, T_H17/IL-17, and T_H22/IL-22 in the pathogenesis of CRC have recently become an increasingly popular area of scientific investigation. Extensive laboratory and clinical evidence suggests a positive relationship between these new T_H subsets and the growth and formation of CRC, whereas, administration of IL-9, IL-17, and IL-22 signaling inhibitors can significantly alter the formation of colorectal chronic inflammation or CRC lesions in animal models, suggesting that blocking these cytokine signals might represent promising immunotherapeutic strategies. This review summarizes recent findings and currently available data for understanding the vital role and therapeutic significance of T_H9/IL-9, T_H17/IL-17, and T_H22/IL-22 in the development of colorectal tumorigenesis.

Interleukin-9 blockage reduces early hepatic granuloma formation and fibrosis during Schistosoma japonicum infection in mice

Hepatic fibrosis induced by schistosomes is regulated by a complex network of cytokines. T helper type 9 (Th9) cells are a new type of effector T helper cells, which mainly secrete the specific cytokine interleukin-9 (IL-9). Interleukin-9 has been shown to contribute to liver fibrosis in patients with chronic hepatitis B and in a mouse model due to carbon tetrachloride. However, the role of IL-9 in schistosomiasis fibrosis remains unknown. In this study, we investigated the roles of IL-9 in schistosomiasis through in vivo and in vitro studies. The in vivo studies found that neutralization of IL-9 reduced liver granulomatous inflammation and collagen deposition around parasite eggs. The in vitro studies found that the treatment of primary hepatic stellate cells with IL-9 induced a significant increase of collagen and α-smooth-muscle actin. Moreover, we also described the dynamics and relevance of IL-9 and IL-4 in mice infected with Schistosoma japonicum. We found that IL-9 might appear more quickly and at higher levels than IL-4. Hence, our findings indicated that IL-9 might play a role in regulating hepatic fibrosis in early-stage schistosomiasis and become a promising approach for regulating hepatic fibrosis caused by S. japonicum.

Biology and regulation of IL-2: from molecular mechanisms to human therapy

IL-2 was first identified as a growth factor capable of driving the expansion of activated human T cell populations. In the more than 40 years since its discovery, a tremendous amount has been learned regarding the mechanisms that regulate the expression of both IL-2 and its cell surface receptor, its mechanisms of signalling and its range of biological actions. More recently, the mechanisms by which IL-2 regulates CD4⁺ T cell differentiation and function have been elucidated. IL-2 also regulates the effector and memory responses of CD8⁺ T cells, and the loss of IL-2 or responsiveness to IL-2 at least in part explains the exhausted phenotype that occurs during chronic viral infections and in tumour responses. These basic mechanistic studies have led to the therapeutic ability to manipulate the action of IL-2 on regulatory T (T_reg) cells for the treatment of autoimmune disease and on CD8⁺ T cells for immunotherapy of cancer. IL-2 can have either positive or deleterious effects, and we discuss here recent ideas and approaches for manipulating the actions and overall net effects of IL-2 in disease settings, including cancer.

Cytokines, growth factors and proteases in medium and large vessel vasculitis

Giant cell arteritis and Takayasu arteritis are autoimmune vasculitides that cause aneurysm formation and tissue infarction. Extravascular inflammation consists of an intense acute phase response. Deeper understanding of pathogenic events in the vessel wall has highlighted the loss of tissue protective mechanisms, the intrusion of immune cells into "forbidden territory", and the autonomy of self-renewing vasculitic infiltrates. Adventitial vasa vasora critically control vessel wall access and drive differentiation of tissue-invasive T cells. Selected T cells establish tissue residency and build autonomous, self-sufficient inflammatory lesions. Pathogenic effector T cells intrude and survive due to failed immune checkpoint inhibition. Vasculitis-sustaining T cells and macrophages provide a broad portfolio of effector functions, involving heterogeneous populations of pro-inflammatory T cells and diverse macrophage subsets that ultimately induce wall capillarization and intimal hyperplasia. Redirecting diagnostic and therapeutic strategies from control of extravascular inflammatory markers to suppression of vascular inflammation will improve disease management.

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.

The amino acid sensor general control nonderepressible 2 (GCN2) controls TH9 cells and allergic airway inflammation

BACKGROUND

T_H9 cells have emerged as important mediators of allergic airway inflammation. There is evidence that general control nonderepressible 2 (GCN2) affects the immune response under some stress conditions. However, whether GCN2 regulates CD4⁺ T-cell differentiation during allergic inflammation remains unknown.

OBJECTIVE

We sought to clarify the regulatory roles of GCN2 in CD4⁺ T-cell subset differentiation and its significance in patients with allergic airway inflammation.

METHODS

The effects of GCN2 in differentiation of T_H cell subsets were detected by using the in vitro induction system. GCN2 knockout mice, ovalbumin-induced allergic airway inflammation, and adoptive transfer mouse models were used to determine the significance of GCN2 in T_H9 differentiation and allergic airway inflammation in vivo. RNA sequencing, real-time PCR, Western blotting, and other molecular approaches were used to identify the molecular mechanisms relevant to regulation of GCN2 in T_H9 cell differentiation.

RESULTS

GCN2 deficiency significantly inhibited differentiation of T_H9 cells but not T_H1, T_H2, and regulatory T cells. GCN2 knockout mice and recombination-activating gene 2 knockout (Rag2KO) mice that received adoptively transferred GCN2-deficient CD4⁺ T cells exhibited reduced T_H9 differentiation and less severe allergic airway inflammation. Furthermore, the isolated GCN2-deficient T_H9 cells also mediated less severe allergic airway inflammation on adoptive transfer. Mechanistically, GCN2 deficiency inhibits T_H9 cell differentiation through a hypoxia-inducible factor 1α-dependent glycolytic pathway.

CONCLUSION

Our results reveal a novel role of GCN2 in T_H9 cell differentiation. Our findings indicate that new strategies to inhibit GCN2 activity might provide novel approaches to attenuate allergic airway inflammation.

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.

T cell subsets: an integral component in pathogenesis of rheumatic heart disease

Acute rheumatic fever (ARF) is a consequence of pharyngeal infection of group A streptococcal (GAS) infection. Carditis is the most common manifestation of ARF which occurs in 30-45% of the susceptible individuals. Overlooked ARF cases might further progress towards rheumatic heart disease (RHD) in susceptible individuals, which ultimately leads to permanent heart valve damage. Molecular mimicry between streptococcal antigens and human proteins is the most widely accepted theory to describe the pathogenesis of RHD. In the recent past, various subsets of T cells have been reported to play an imperative role in the pathogenesis of RHD. Alterations in various T cell subsets, viz. Th1, Th2, Th17, and Treg cells, and their signature cytokines influence the immune responses and are associated with pathogenesis of RHD. Association of other T cell subsets (Th3, Th9, Th22, and T_FH) is not defined in context of RHD. Several investigations have confirmed the up-regulation of adhesion molecules and thus infiltration of T cells into the heart tissues. T cells secrete both Th type 1 and type 2 cytokines and these auto-reactive T cells play a key role in progression of heart valve damage. In this review, we are going to discuss about the role of T cell subsets and their corresponding cytokines in the pathogenesis of RHD.

Exploiting PLGA-Based Biocompatible Nanoparticles for Next-Generation Tolerogenic Vaccines against Autoimmune Disease

Tolerogenic vaccines are aimed at inhibiting antigen-specific immune responses. Antigen-loaded nanoparticles (NPs) have been recently emerged as ideal tools for tolerogenic vaccination because their composition, size, and capability of loading immunomodulatory molecules can be readily exploited to induce peripheral tolerance. Among polymeric NPs, poly(lactic-co-glycolic acid) (PLGA) NPs have the advantage of currently holding approval for several applications in drug delivery, diagnostics, and other clinical uses by the Food and Drug Administration (FDA). PLGA-NPs are non-toxic and display excellent biocompatibility and biodegradability properties. Moreover, surface functionalization may improve their interaction with biological materials, thereby optimizing targeting and performance. PLGA-NPs are the most extensively studied in pre-clinical model in the field of tolerogenic vaccination. Thus, this review describes their potential applications in the treatment of autoimmune diseases.

Structural Basis for Signaling Through Shared Common γ Chain Cytokines

The common γ chain (γ_c) family of hematopoietic cytokines consists of six distinct four α-helix bundle soluble ligands that signal through receptors which include the shared γ_c subunit to coordinate a wide range of physiological processes, in particular, those related to innate and adaptive immune function. Since the first crystallographic structure of a γ_c family cytokine/receptor signaling complex (the active Interleukin-2 [IL-2] quaternary complex) was determined in 2005 [1], tremendous progress has been made in the structural characterization of this protein family, transforming our understanding of the molecular mechanisms underlying immune activity. Although many conserved features of γ_c family cytokine complex architecture have emerged, distinguishing details have been observed for individual cytokine complexes that rationalize their unique functional properties. Much work remains to be done in the molecular characterization of γ_c family signaling, particularly with regard to intracellular activation events, and looking forward, new technologies in structural biophysics will offer further insight into the biology of cytokine signaling to inform the design of targeted therapeutics for treatment of immune-linked diseases such as cancer, infection, and autoimmune disorders.

Features and roles of T helper 9 cells and interleukin 9 in immunological diseases

T helper 9 (T_H9) cells are considered as newly classified helper T cells that have an important role in the regulation of immune responses. Since these cells preferentially produce IL-9, these cells are termed T_H9 cells. Recently, the role of T_H9 and its signature cytokine (IL-9) has been investigated in a wide range of diseases, including autoimmunity, allergy, infections, cancer and immunodeficiency. Herein, we review the most recent data concerning T_H9 cells and IL-9 as well as their roles in disease. These insights suggest that T_H9 cells are a future target for therapeutic intervention.

Th17 response in patients with cervical cancer

Persistent infection by high-risk human papillomavirus (HR-HPV) is the main risk factor for uterine cervical cancer (UCC). However, viral infection alone is not sufficient for the development and progression of premalignant cervical lesions for cancer. In previous years it has been suggested that the adaptive immune response triggered by the differentiation of naïve helper T cells in Th17 cells may serve an important role in disease development. It has been hypothesized that Th17 cells may be involved in the promotion of UCC, as high levels of interleukin 17 (IL17) expression have been detected in the mucosa of the uterine cervix of patients affected by the disease. However, the role of Th17 cells in the tumor development and progression remains unclear. It is believed that the immune response of the Th17 type during persistent infection of the genital tract with HR-HPV triggers chronic inflammation with a long duration with the production of IL17 and other pro-inflammatory cytokines, creating a favorable environment for tumor development. These cytokines are produced by immune system cells in addition to tumor cells and appear to function by modulating the host immune system, resulting in an immunosuppressive response as opposed to inducing an effective protective immune response, thus contributing to the growth and progression of the tumor. In the present review, the latest advances are presented about the function of Th17 cells and the cytokines produced by them in the development and progression of UCC.

T Helper Cell Subsets in Experimental Lung Allograft Rejection

BACKGROUND

Human lung transplantation has evolved to an established treatment for pulmonary diseases in their end stages; however, the long-term outcome is worse when compared to all other solid transplantable organs. The major reason for this unfavorable outcome is rejection, either in its acute or chronic form, the latter termed as chronic lung allograft dysfunction.

METHODS

A systematic review search was performed.

RESULTS

One of the most important immune cells responsible for rejection are T cells. Beside alloreactive CD8+ T cells, CD4+ T cells play a key role during the evolvement of allograft rejection. Certain subsets of these allograft CD4+ T cells have been identified which have been shown to exert either transplant-protective or transplant-injuring properties. These effects have been proven in various experimental models, mainly in rats and mice, and allowed for the gain of important insights into these proinflammatory and anti-inflammatory characteristics including their targetability: while the subsets Th1, Th17, Th22, and Tfh cells have been shown to act in a rather proinflammatory way, Tregs, Th2, and Th9 subsets exert anti-inflammatory effects. Chronic airway obstruction is mainly induced by IL17 as shown across models.

CONCLUSIONS

This review shall summarize and provide an overview of the current evidence about the role and effects of proinflammatory and anti-inflammatory CD4-+ T helper cell subsets during lung allograft rejection in experimental rodent models.

Role of Cytokine Combinations on CD4+ T Cell Differentiation, Partial Polarization, and Plasticity: Continuous Network Modeling Approach

Purpose: We put forward a theoretical and dynamical approach for the semi-quantitative analysis of CD4+ T cell differentiation, the process by which cells with different functions are derived from activated CD4+ T naïve lymphocytes in the presence of particular cytokine microenvironments. We explore the system-level mechanisms that underlie CD4+ T plasticity-the conversion of polarized cells to phenotypes different from those originally induced. Methods: In this paper, we extend a previous study based on a Boolean network to a continuous framework. The network includes transcription factors, signaling pathways, as well as autocrine and exogenous cytokines, with interaction rules derived using fuzzy logic. Results: This approach allows us to assess the effect of relative differences in the concentrations and combinations of exogenous and endogenous cytokines, as well as of the expression levels of diverse transcription factors. We found either abrupt or gradual differentiation patterns between observed phenotypes depending on critical concentrations of single or multiple environmental cytokines. Plastic changes induced by environmental cytokines were observed in conditions of partial phenotype polarization in the T helper 1 to T helper 2 transition. On the other hand, the T helper 17 to induced regulatory T-cells transition was highly dependent on cytokine concentrations, with TGFβ playing a prime role. Conclusion: The present approach is useful to further understand the system-level mechanisms underlying observed patterns of CD4+ T differentiation and response to changing immunological challenges.

A Mechanistic Computational Model Reveals That Plasticity of CD4+ T Cell Differentiation Is a Function of Cytokine Composition and Dosage

CD4⁺ T cells provide cell-mediated immunity in response to various antigens. During an immune response, naïve CD4⁺ T cells differentiate into specialized effector T helper (Th1, Th2, and Th17) cells and induced regulatory (iTreg) cells based on a cytokine milieu. In recent studies, complex phenotypes resembling more than one classical T cell lineage have been experimentally observed. Herein, we sought to characterize the capacity of T cell differentiation in response to the complex extracellular environment. We constructed a comprehensive mechanistic (logical) computational model of the signal transduction that regulates T cell differentiation. The model's dynamics were characterized and analyzed under 511 different environmental conditions. Under these conditions, the model predicted the classical as well as the novel complex (mixed) T cell phenotypes that can co-express transcription factors (TFs) related to multiple differentiated T cell lineages. Analyses of the model suggest that the lineage decision is regulated by both compositions and dosage of signals that constitute the extracellular environment. In this regard, we first characterized the specific patterns of extracellular environments that result in novel T cell phenotypes. Next, we predicted the inputs that can regulate the transition between the canonical and complex T cell phenotypes in a dose-dependent manner. Finally, we predicted the optimal levels of inputs that can simultaneously maximize the activity of multiple lineage-specifying TFs and that can drive a phenotype toward one of the co-expressed TFs. In conclusion, our study provides new insights into the plasticity of CD4⁺ T cell differentiation, and also acts as a tool to design testable hypotheses for the generation of complex T cell phenotypes by various input combinations and dosages.

Involvement of T-Helper 9 Activation in a Mouse Model of Allergic Rhinitis

Background

We aimed to investigate the role of T-Helper (TH) 9 cells in the pathogenesis of allergic rhinitis (AR) in mice.

Material/Methods

An AR model was produced in BALB/c mice, and the viral encoding interleukin (IL)-9 silencing sequence was used to reduce IL-9 expression. The experiment was divided into a control group, an AR group, an IL-9 shRNA+AR group, and a vector+AR group. Hematoxylin and eosin (H&E) staining was used to detect pathological changes. The cytokine expression was detected by ELISA method. Cellular typing was detected by flow cytometry.

Results

Cells in the control group were regularly arranged, with clear layers and no congestion, edema, or necrosis observable. By contrast, in the AR model group and the vector treatment group, nasal mucosa showed clear hyperemia and edema in upper tissues and infiltration of inflammatory cells, which were ameliorated by IL-9 silencing. Compared with the control group, interferon-γ (IFN-γ) was significantly down-regulated, while IL-4, IL-17, and IL-9 were significantly elevated in the AR model group. TH1 cells in nasal mucosa, lymph, nasal lavage, spleen, and peripheral blood were significantly reduced, while TH2, TH9, TH17, and Treg cells were significantly elevated in the AR group compared with the control group. Importantly, all these changes in AR model were ameliorated by IL-9 silencing.

Conclusions

AR is related to the changes of cytokines in TH1, TH2, TH9, TH17, and Treg, which are improved by IL-9 silencing. Activation of TH9 cells is involved in the pathogenesis of AR.

Role of T-Helper 9 Cells in Chronic Hepatitis C-Infected Patients

Hepatitis C virus is a hepatotropic virus that is transmitted parenterally. Viral infections are usually associated with modulations of the immune cells, leading to enhanced viral survival and spreading, and accordingly, life-threatening complications. Recently, it has been proposed that a new subset of T-helper, named T-helper 9, is involved in the pathogenesis of different immunopathological conditions, such as allergies, tumors, and viral infections. Some studies reported a protective role, and others described a pathogenic potential for the T-helper 9 cells. Here, we present evidence that T-helper 9 cells are dynamically increased with increasing the pathogenic strategy for hepatitis C virus (HCV). Furthermore, viral clearance is associated with a decrease in T-helper 9. The increase in T-helper 9 was paralleled with an increase in its receptor expression. Taken together, our data suggest that T-helper 9 cells play an important role in the pathogenesis of HCV, and is directly associated with HCV-related complications.

CXCL10-induced IL-9 promotes liver fibrosis via Raf/MEK/ERK signaling pathway

Liver fibrosis is a typical complication of chronic liver diseases resulting in cirrhosis that remains a major public health problem. The aim of the present study was to identify the role of interleukin-9 (IL-9), an important regulator of inflammation and autoimmune diseases, in hepatic fibrosis progression. It was found that the expression of IL-9 was significantly increased in liver tissues of liver cirrhosis patients compared with that in healthy controls. Moreover, CXCL10, not CXCL9 or CXCL11, induced IL-9 expression in the liver tissue. Overexpression of IL-9 enhanced the severity of liver fibrosis in the carbon tetrachloride (CCl₄)-induced liver fibrosis model. Western Blotting analysis revealed that this pro-fibrosis bioactivity of IL-9 was attributed to its selective activation of Raf/MEK/ERK signaling. Finally, administration of neutralizing anti-IL-9 antibody ameliorated liver fibrosis and attenuated the activation of hepatic stellate cells in mice. All these findings indicate that IL-9 plays a deleterious role in the development and progression of liver fibrosis, and IL-9 based immunotherapy may prove to be a promising strategy for the treatment of liver fibrosis.

Th1/Th17/Th22 immune response and their association with joint pain, imagenological bone loss, RANKL expression and osteoclast activity in temporomandibular joint osteoarthritis: A preliminary report

It is well accepted that the presence of cytokines belonging to the Th1/Th17/Th22 axis of immuno-inflammatory response in the joint environment, such as IL-1β, IL-17 and IL-22, respectively, are associated with pathogenesis of several synovial joint degenerative disorders. During temporomandibular joint osteoarthritis (TMJ-OA), IL-1β and IL-17 have been implicated in the inflammation and resorption of sub-chondral bone; however, the role of Th22 response in the TMJ-OA pathophysiology has not been established. This study aimed to compare the expression of Th1/Th17/Th22-type cytokines, chemokines and chemokine receptors in synovial fluid samples obtained from TMJ-OA or disk displacement with reduction (DDWR) patients. In addition, it aimed to associate these levels with joint pain, imagenological signs of bone degeneration, RANKL production, osteoclastogenesis and osteoclast-induced bone resorption. Higher levels of IL-1β, IL-17 and IL-22 were expressed in TMJ-OA compared with DDWR subjects, and these increased levels significantly correlated with RANKL expression, joint pain and articular bone degeneration. Higher levels of CCR5, CCR6 and CCR7, as well as their respective ligands CCL5 and CCL20, responsible for recruitment of IL-1β, IL-17 and IL-22-producing cells, were over-expressed in TMJ-OA compared with DDWR subjects. Osteoclastogenesis and osteoclast-induced bone resorption were significantly greater in presence of synovial fluid from TMJ-OA compared with DDWR subjects. These data demonstrate that cytokines, CCLs and CCRs associated with the Th1/Th17/Th22 axis of immuno-inflammatory response are involved in TMJ-OA pathogenesis. These findings suggest that IL-22 is involved in the RANKL expression in TMJ-OA, which in turn induces differentiation of osteoclasts and subsequent resorption of sub-chondral bone.

IL-9 Deficiency Promotes Pulmonary Th17 Response in Murine Model of Pneumocystis Infection

Introduction

Pneumocystis pneumonia (PCP) remains a severe complication with high mortality in immunocompromised patients. It has been well accepted that CD4⁺ T cells play a major role in controlling Pneumocystis infection. Th9 cells were the main source of IL-9 with multifaced roles depending on specific diseases. It is unclear whether IL-9/Th9 contributes to the immune response against PCP. The current study aims to explore the role of IL-9 and the effect of IL-9 on Th17 cells in murine model of PCP.

Materials and methods

Mice were intratracheally injected with 1 × 10⁶Pneumocystis organisms to establish the murine model of Pneumocystis infection. Pneumocystis burden was detected by TaqMan real-time PCR. Using IL-9-deficient (IL-9^−/−) mice, flow cytometry, real-time PCR and enzyme-linked immunosorbent assay (ELISA) were conducted to investigate the immune function related to Th17 response in defense against Pneumocystis infection.

Results

Reduced Pneumocystis burden was observed in lungs in IL-9^−/− mice compared with WT mice at 3-week postinfection. IL-9^−/−mice exhibited stronger Th17 immune responses than WT PCP mice through flow cytometer and real-time PCR. ELISA revealed higher levels of IL-17 and IL-23 in bronchoalveolar lavage fluid from IL-9^−/− mice than WT mice. And IL-9 deficiency promoted Th17 differentiation from CD4⁺ naive T cells. IL-17A neutralization increased Pneumocystis burden in IL-9^−/− mice.

Conclusion

Although similar basic clearance of Pneumocystis organisms was achieved in both WT and IL-9^−/− PCP mice, IL-9 deficiency could lower Pneumocystis organism burden and promote pulmonary Th17 cells response in the early stage of infection.

A Decade of Th9 Cells: Role of Th9 Cells in Inflammatory Bowel Disease

T helper cell subsets play a critical role in providing protection against offending pathogens by secreting specific cytokines. However, unrestrained T helper cell responses can promote chronic inflammation-mediated inflammatory diseases. Dysregulated T helper cell responses have been suggested to be involved in the pathogenesis of multiple inflammatory diseases, including allergic airway inflammation, rheumatoid arthritis, and inflammatory bowel disease (IBD) among others. Aberrant pro-inflammatory responses induced by Th1, Th2, and Th17 subsets are known to trigger IBD. IBD is a chronic inflammatory disease characterized by weight loss, diarrhea, pain, fever, and rectal bleeding. It poses a major health burden worldwide owing to the increased risk of colorectal cancer development. Despite numerous therapeutic advancements, IBD still remains a major health burden due to the inefficiency of the conventional therapies. Recently, IL-9-secreting Th9 cells are known to be involved in the pathogenesis of IBD. However, the role of Th9 cells and their secretory cytokine IL-9 in IBD is unclear. The functional relevance of Th9 cells is also relatively understudied in IBD. Thus, investigating the actual role of various T helper cell subsets including Th9 cells in IBD is essential to develop novel therapies to treat IBD. Here, we highlight the role of Th9 cells in promoting IBD. We discuss the mechanisms that might be employed by Th9 cells and IL-9 in promoting IBD and thereby propose potential targets for the treatment of Th9 cell-mediated IBD.

Immunological Processes Driving IgE Sensitisation and Disease Development in Males and Females

IgE sensitisation has increased significantly over the last decades and is a crucial factor in the development of allergic diseases. IgE antibodies are produced by B cells through the process of antigen presentation by dendritic cells, subsequent differentiation of CD4⁺ Th2 cells, and class switching in B cells. However, many of the factors regulating these processes remain unclear. These processes affect males and females differently, resulting in a significantly higher prevalence of IgE sensitisation in males compared to females from an early age. Before the onset of puberty, this increased prevalence of IgE sensitisation is also associated with a higher prevalence of clinical symptoms in males; however, after puberty, females experience a surge in the incidence of allergic symptoms. This is particularly apparent in allergic asthma, but also in other allergic diseases such as food and contact allergies. This has been partly attributed to the pro- versus anti-allergic effects of female versus male sex hormones; however, it remains unclear how the expression of sex hormones translates IgE sensitisation into clinical symptoms. In this review, we describe the recent epidemiological findings on IgE sensitisation in male and females and discuss recent mechanistic studies casting further light on how the expression of sex hormones may influence the innate and adaptive immune system at mucosal surfaces and how sex hormones may be involved in translating IgE sensitisation into clinical manifestations.

Cholesterol negatively regulates IL-9-producing CD8+ T cell differentiation and antitumor activity

CD8⁺ T cells can be polarized into IL-9-secreting (Tc9) cells. We previously showed that adoptive therapy using tumor-specific Tc9 cells generated stronger antitumor responses in mouse melanoma than classical Tc1 cells. To understand why Tc9 cells exert stronger antitumor responses, we used gene profiling to compare Tc9 and Tc1 cells. Tc9 cells expressed different levels of cholesterol synthesis and efflux genes and possessed significantly lower cholesterol content than Tc1 cells. Unique to Tc9, but not other CD8⁺ or CD4⁺ T cell subsets, manipulating cholesterol content in polarizing Tc9 cells significantly affected IL-9 expression and Tc9 differentiation and antitumor response in vivo. Mechanistic studies showed that IL-9 was indispensable for Tc9 cell persistence and antitumor effects, and cholesterol or its derivatives inhibited IL-9 expression by activating liver X receptors (LXRs), leading to LXR Sumoylation and reduced p65 binding to Il9 promoter. Our study identifies cholesterol as a critical regulator of Tc9 cell differentiation and function.

Th9 Cells: Probable players in ulcerative colitis pathogenesis

T lymphocytes represent an important part of adaptive immune system undertaking different functions to regulate immune responses. CD4+ T cells are the most important activator cells in inflammatory conditions. Depending on the type of induced cells and inflamed sites, expression and activity of different subtypes of helper T cells are changed. Recent studies have confirmed the existence of a new subset of helper T lymphocytes called Th9. Naive T cells can differentiate into Th9 subtypes if they are exposed simultaneously by interleukin (IL) 4 and transforming growth factor β and also secondary activation of a complicated network of transcription factors such as interferon regulatory factor 4 (IRF4) and Smads which are essential for adequate induction of this phenotype. Th9 cells specifically produce interleukin 9 and their probable roles in promoting intestinal inflammation are being investigated in human subjects and experimental models of ulcerative colitis (UC). Recently, infiltration of Th9 cells, overexpression of IL-9, and certain genes associated with Th9 differentiation have been demonstrated in inflammatory microenvironment of UC. Intestinal oversecretion of IL-9 protein is likely to break down epithelial barriers and compromise tolerance to certain commensal microorganisms which leads to inflammation. Th9 pathogenicity has not yet been adequately explored in UC and they are far from being considered as inflammatory cells in this milieu, therefore precise understanding the role of these newly identified cells in particular their potential role in gut pathogenesis may enable us to develop novel therapeutic approaches for inflammatory bowel disease. So, this article tries to discuss the latest knowledge on the above-mentioned field.