The symphony of the ninth: the development and function of Th9 cells

The emerging role of T helper 9 (Th9) cells in immunopathophysiology: A comprehensive review of their effects and responsiveness in various disease states

Th9 cells, a subset of T-helper cells producing interleukin-9 (IL-9), play a vital role in the adaptive immune response and have diverse effects in different diseases. Regulated by transcription factors like PU.1 and IRF4, and cytokines such as IL-4 and TGF-β, Th9 cells drive tissue inflammation. This review focuses on their emerging role in immunopathophysiology. Th9 cells exhibit immune-mediated cancer cell destruction, showing promise in glioma and cervical cancer treatment. However, their role in breast and lung cancer is intricate, requiring a deeper understanding of pro- and anti-tumor aspects. Th9 cells, along with IL-9, foster T cell and immune cell proliferation, contributing to autoimmune disorders. They are implicated in psoriasis, atopic dermatitis, and infections. In allergic reactions and asthma, Th9 cells fuel pro-inflammatory responses. Targeting Foxo1 may regulate innate and adaptive immune responses, alleviating disease symptoms. This comprehensive review outlines Th9 cells' evolving immunopathophysiological role, emphasizing the necessity for further research to grasp their effects and potential therapeutic applications across diseases.

The TGF-β superfamily as potential therapeutic targets in pancreatic cancer

The transforming growth factor (TGF)-β superfamily has important physiologic roles and is dysregulated in many pathologic processes, including pancreatic cancer. Pancreatic cancer is one of the most lethal cancer diagnoses, and current therapies are largely ineffective due to tumor resistance and late-stage diagnosis with poor prognosis. Recent efforts are focused on the potential of immunotherapies in improving therapeutic results for patients with pancreatic cancer, among which TGF-β has been identified as a promising target. This review focuses on the role of TGF-β in the diseased pancreas and pancreatic cancer. It also aims to summarize the current status of therapies targeting the TGF-β superfamily and postulate potential future directions in targeting the TGF-β signaling pathways.

IL-9-Producing Th9 Cells Participate in the Occurrence and Development of Iodine-Induced Autoimmune Thyroiditis

Iodine excess may cause and aggravate autoimmune thyroiditis (AIT), which is regarded as a typical kind of autoimmune disease mainly mediated by CD4+ T cells. Thus far, it is unclear whether T helper (Th) 9 cells, a novel subpopulation of CD4+ T cells, play a potential role in AIT. Therefore, in the present study, changes in Th9 cells were detected in murine models of AIT induced by excess iodine intake to explore the possible immune mechanism. Female C57BL/6 mice were divided into 7 groups (n = 8) and were supplied with water containing 0.005% sodium iodide for 0, 2, 4, 6, 8, 10, and 12 weeks. With the extension of the high-iodine intake duration, the incidence of thyroiditis and the spleen index were significantly increased, and serum thyroglobulin antibody (TgAb) titers and interleukin 9 (IL-9, major cytokine from Th9 cells) concentrations were also increased. Additionally, it was revealed that the percentages of Th9 cells in spleen mononuclear cells (SMCs) and thyroid tissues were both markedly elevated and accompanied by increased mRNA and protein expression of IL-9 and key transcription factors of Th9 cells (PU.1 and IRF-4). Significantly, dynamic changes in Th9 cells were found, with a peak at 8 weeks after high iodine intake, the time point when thyroiditis was the most serious. Importantly, Th9 cells were detected in the areas of infiltrating lymphocytes in thyroid sections. In conclusion, the continuously increasing proportions of Th9 cells may play an important role in the occurrence and development of AIT induced by high iodine intake.

TGF-β as A Master Regulator of Aging-Associated Tissue Fibrosis

Fibrosis is the abnormal accumulation of extracellular matrix proteins such as collagen and fibronectin. Aging, injury, infections, and inflammation can cause different types of tissue fibrosis. Numerous clinical investigations have shown a correlation between the degree of liver and pulmonary fibrosis in patients and telomere length and mitochondrial DNA content, both of which are signs of aging. Aging involves the gradual loss of tissue function over time, which results in the loss of homeostasis and, ultimately, an organism's fitness. A major feature of aging is the accumulation of senescent cells. Senescent cells abnormally and continuously accumulate in the late stages of life, contributing to age-related fibrosis and tissue deterioration, among other aging characteristics. Furthermore, aging generates chronic inflammation, which results in fibrosis and decreases organ function. This finding suggests that fibrosis and aging are closely related. The transforming growth factor-beta (TGF-β) superfamily plays a crucial role in the physiological and pathological processes of aging, immune regulation, atherosclerosis, and tissue fibrosis. In this review, the functions of TGF-β in normal organs, aging, and fibrotic tissues is discussed: TGF-β signalling is altered with age and is an indicator of pathology associated with tissue fibrosis. In addition, this review discusses the potential targeting of noncoding.

Post-COVID-19 syndrome: Insights into a novel post-infectious systemic disorder

Coronavirus disease 2019 (COVID-19) is currently considered a complex systemic infectious and inflammatory disease, determined by the infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), and the cause of one of the most important epidemiological phenomena in the last century - the COVID-19 pandemic. This infectious-inflammatory disease may generate a wide range of clinical manifestations and biological modifications, explained by the ubiquitous nature of the SARS-CoV-2 receptors, represented by the angiotensin-converting enzyme-2 (ACE-2), and by the host's violent immune and proinflammatory reaction to the viral infection. These manifestations include immunological disturbances, which, according to certain clinical findings, may persist post-infection, in the form of a presumed systemic inflammatory entity, defined by several clinical concepts with a common pathological significance: post-COVID-19 multisystem (or systemic) inflammatory syndrome, post-COVID syndrome or long-COVID. Although the pathophysiological mechanisms of the post-COVID-19 syndrome are elusive at the present moment, there are currently several studies that describe a systemic inflammatory or autoimmune phenomenon following the remission of the COVID-19 infection in some patients, which suggests the existence of molecular and cellular immune abnormalities, most probably due to the host's initial violent immune response to the viral infection, in the form of three overlapping entities: secondary hemophagocytic lymph histiocytosis (HLH), macrophage activation syndrome (MAS) and cytokine release syndrome (CRS). Thus, this is reminiscent of different classic autoimmune diseases, in which various infections are risk factors in developing the autoimmune process.

Targeting TGF-β signaling in the multiple myeloma microenvironment: Steering CARs and T cells in the right direction

Multiple myeloma (MM) remains a lethal hematologic cancer characterized by the expansion of transformed plasma cells within the permissive bone marrow (BM) milieu. The emergence of relapsed and/or refractory MM (RRMM) is provoked through clonal evolution of malignant plasma cells that harbor genomic, metabolic and proteomic perturbations. For most patients, relapsed disease remains a major cause of overall mortality. Transforming growth factors (TGFs) have pleiotropic effects that regulate myelomagenesis as well as the emergence of drug resistance. Moreover, TGF-β modulates numerous cell types present with the tumor microenvironment, including many immune cell types. While numerous agents have been FDA-approved over the past 2 decades and significantly expanded the treatment options available for MM patients, the molecular mechanisms responsible for drug resistance remain elusive. Multiple myeloma is uniformly preceded by a premalignant state, monoclonal gammopathy of unknown significance, and both conditions are associated with progressive deregulation in host immunity characterized by reduced T cell, natural killer (NK) cell and antigen-presenting dendritic cell (DC) activity. TGF-β promotes myelomagenesis as well as intrinsic drug resistance by repressing anti-myeloma immunity to promote tolerance, drug resistance and disease progression. Hence, repression of TGF-β signaling is a prerequisite to enhance the efficacy of current and future immunotherapeutics. Novel strategies that incorporate T cells that have been modified to express chimeric antigen receptor (CARs), T cell receptors (TCRs) and bispecific T cell engagers (BiTEs) offer promise to block TGF-β signaling, overcome chemoresistance and enhance anti-myeloma immunity. Here, we describe the effects of TGF-β signaling on immune cell effectors in the bone marrow and emerging strategies to overcome TGF-β-mediated myeloma growth, drug resistance and survival.

mTOR Signaling in the Regulation of CD4+ T Cell Subsets in Periodontal Diseases

Periodontal disease results from the inflammatory infiltration by the microbial community which is marked through tooth mobility and alveolar bone resorption. The inflammation in periodontal disease is mediated by CD4⁺ T cells through cytokine secretion and osteoclastogenetic activity. Historically, the inflammatory model in periodontal disease is described through disruption of the balance between two subsets of T helper cells which are T-helper type 1 (Th1) and T-helper type 2 (Th2). However, more and more studies have found that apart from subsets of helper T cells, regulatory T-cells and Th17 cells are also involved in the pathogenesis of periodontal diseases. Growing evidence proves that helper T cells differentiation, activation, and subset determination are under the strong impact of mTOR signaling. mTOR signaling could promote Th1 and Th17 cell differentiation and inhibit Treg commitment through different mTOR complexes, therefore we anticipate a regulation effect of mTOR signaling on periodontal diseases by regulating CD4⁺ T cell subsets. This review aims to integrate the topical researches about the role of different types of Th cells in the pathogenesis of periodontal diseases, as well as the regulation of mTOR signaling in the specification and selection of Th cell commitment.

Persistent Autoimmune Activation and Proinflammatory State in Post-COVID Syndrome

Background

The immunopathological pathways enabling post-COVID syndrome (PCS) development are not entirely known. We underwent a longitudinal analysis of patients with COVID-19 who developed PCS aiming to evaluate the autoimmune and immunological status associated with this condition.

Methods

Thirty-three patients were included for longitudinal clinical and autoantibody analyses of whom 12 patients were assessed for cytokines and lymphocyte populations. Patients were followed during 7-11 months after acute COVID-19. Autoimmune profile and immunological status were evaluated mainly by enzyme-linked-immunosorbent assays and flow cytometry.

Results

Latent autoimmunity and overt autoimmunity persisted over time. A proinflammatory state was observed in patients with PCS characterized by upregulated IFN-α, TNF-α, G-CSF, IL-17A, IL-6, IL-1β, and IL-13, whereas IP-10 was decreased. In addition, PCS was characterized by increased levels of Th9, CD8+ effector T cells, naive B cells, and CD4+ effector memory T cells. Total levels of IgG S1-SARS-CoV-2 antibodies remained elevated over time.

Discussion

The clinical manifestations of PCS are associated with the persistence of a proinflammatory, and effector phenotype induced by SARS-CoV-2 infection. This long-term persistent immune activation may contribute to the development of latent and overt autoimmunity. Results suggest the need to evaluate the role of immunomodulation in the treatment of PCS.

Gut CD4+ T cell phenotypes are a continuum molded by microbes, not by TH archetypes

CD4+ effector lymphocytes (Teff) are traditionally classified by the cytokines they produce. To determine the states that Teff cells actually adopt in frontline tissues in vivo, we applied single-cell transcriptome and chromatin analyses to colonic Teff cells in germ-free or conventional mice or in mice after challenge with a range of phenotypically biasing microbes. Unexpected subsets were marked by the expression of the interferon (IFN) signature or myeloid-specific transcripts, but transcriptome or chromatin structure could not resolve discrete clusters fitting classic helper T cell (TH) subsets. At baseline or at different times of infection, transcripts encoding cytokines or proteins commonly used as TH markers were distributed in a polarized continuum, which was functionally validated. Clones derived from single progenitors gave rise to both IFN-γ- and interleukin (IL)-17-producing cells. Most of the transcriptional variance was tied to the infecting agent, independent of the cytokines produced, and chromatin variance primarily reflected activities of activator protein (AP)-1 and IFN-regulatory factor (IRF) transcription factor (TF) families, not the canonical subset master regulators T-bet, GATA3 or RORγ.

Green Tea Polyphenol-Sensitive Calcium Signaling in Immune T Cell Function

Polyphenol compounds found in green tea have a great therapeutic potential to influence multiple human diseases including malignancy and inflammation. In this mini review, we describe effects of green tea and the most important component EGCG in malignancy and inflammation. We focus on cellular mechanisms involved in the modification of T cell function by green tea polyphenol EGCG. The case is made that EGCG downregulates calcium channel activity by influencing miRNAs regulating expression of the channel at the post-transcriptional level.

Peripheral Blood Immune Profiling of Convalescent Plasma Donors Reveals Alterations in Specific Immune Subpopulations Even at 2 Months Post SARS-CoV-2 Infection

Immune profiling of patients with COVID-19 has shown that SARS-CoV-2 causes severe lymphocyte deficiencies (e.g., lymphopenia, decreased numbers, and exhaustion of T cells) and increased levels of pro-inflammatory monocytes. Peripheral blood (PB) samples from convalescent plasma (CP) donors, COVID-19 patients, and control subjects were analyzed by multiparametric flow cytometry, allowing the identification of a wide panel of immune cells, comprising lymphocytes (T, B, natural killer (NK) and NKT cells), monocytes, granulocytes, and their subsets. Compared to active COVID-19 patients, our results revealed that the immune profile of recovered donors was restored for most subpopulations. Nevertheless, even 2 months after recovery, CP donors still had reduced levels of CD4+ T and B cells, as well as granulocytes. CP donors with non-detectable levels of anti-SARS-CoV-2-specific antibodies in their serum were characterized by higher Th9 and Th17 cells, which were possibly expanded at the expense of Th2 humoral immunity. The most noticeable alterations were identified in previously hospitalized CP donors, who presented the lowest levels of CD8+ regulatory T cells, the highest levels of CD56+CD16- NKT cells, and a promotion of a Th17-type phenotype, which might be associated with a prolonged pro-inflammatory response. A longer follow-up of CP donors will eventually reveal the time needed for full recovery of their immune system competence.

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.

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.

T Lymphocytes: A Promising Immunotherapeutic Target for Pancreatitis and Pancreatic Cancer?

Pancreatic disorders cause a broad spectrum of clinical diseases, mainly including acute and chronic pancreatitis and pancreatic cancer, and are associated with high global rates of morbidity and mortality. Unfortunately, the pathogenesis of pancreatic disease remains obscure, and there is a lack of specific treatments. T lymphocytes (T cells) play a vital role in the adaptive immune systems of multicellular organisms. During pancreatic disease development, local imbalances in T-cell subsets in inflammatory and tumor environments and the circulation have been observed. Furthermore, agents targeting T cells have been shown to reverse the natural course of pancreatic diseases. In this review, we have discussed the clinical relevance of T-cell alterations as a potential outcome predictor and the underlying mechanisms, as well as the present status of immunotherapy targeting T cells in pancreatitis and neoplasms. The breakthrough findings summarized in this review have important implications for innovative drug development and the prospective use of immunotherapy for pancreatitis and pancreatic cancer.

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.

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.

Transforming growth factor-β in pancreatic diseases: Mechanisms and therapeutic potential

Pancreatic diseases, such as acute pancreatitis, chronic pancreatitis, and pancreatic cancer, are common gastrointestinal diseases resulting in the development of local and systemic complications with a high risk of death. Numerous studies have examined pancreatic diseases over the past few decades; however, the pathogenesis remains unclear, and there is a lack of effective treatment options. Recently, emerging evidence has suggested that transforming growth factor beta (TGF-β) exerts controversial functions in apoptosis, inflammatory responses, and carcinogenesis, indicating its complex role in the pathogenesis of pancreas-associated disease. Therefore, a further understanding of relevant TGF-β signalling will provide new ideas and potential therapeutic targets for preventing disease progression. This is the first systematic review of recent data from animal and human clinical studies focusing on TGF-β signalling in pancreas damage and diseases. This information may aid in the development of therapeutic agents for regulating TGF-β in this pathology to prevent or treat pancreatic diseases.

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.

Innate Lymphoid Cells (ILCs): Cytokine Hubs Regulating Immunity and Tissue Homeostasis

Innate lymphoid cells (ILCs) have emerged as an expanding family of effector cells particularly enriched in the mucosal barriers. ILCs are promptly activated by stress signals and multiple epithelial- and myeloid-cell-derived cytokines. In response, ILCs rapidly secrete effector cytokines, which allow them to survey and maintain the mucosal integrity. Uncontrolled action of ILCs might contribute to tissue damage, chronic inflammation, metabolic diseases, autoimmunity, and cancer. Here we discuss the recent advances in our understanding of the cytokine network that modulate ILC immune responses: stimulating cytokines, signature cytokines secreted by ILC subsets, autocrine cytokines, and cytokines that induce cell plasticity.

Identification of biomarker sets for predicting the efficacy of sublingual immunotherapy against pollen-induced allergic rhinitis

Sublingual immunotherapy (SLIT) is effective against allergic rhinitis, although a substantial proportion of individuals is refractory. Herein, we describe a predictive modality to reliably identify SLIT non-responders (NRs). We conducted a 2-year clinical study in 193 adult patients with Japanese cedar pollinosis, with biweekly administration of 2000 Japanese allergy units of cedar pollen extract as the maintenance dose. After identifying high-responder (HR) patients with improved severity scores and NR patients with unchanged or exacerbated symptoms, differences in 33 HR and 34 NR patients were evaluated in terms of peripheral blood cellular profiles by flow cytometry and serum factors by ELISA and cytokine bead array, both pre- and post-SLIT. Improved clinical responses were seen in 72% of the treated patients. Pre-therapy IL-12p70 and post-therapy IgG1 serum levels were significantly different between HR and NR patients, although these parameters alone failed to distinguish NR from HR patients. However, the analysis of serum parameters in the pre-therapy samples with the Adaptive Boosting (AdaBoost) algorithm distinguished NR patients with high probability within the training data set. Cluster analysis revealed a positive correlation between serum Th1/Th2 cytokines and other cytokines/chemokines in HR patients after SLIT. Thus, processing of pre-therapy serum parameters with AdaBoost and cluster analysis can be reliably used to develop a prediction method for HR/NR patients.

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.

Immunoporosis: Immunology of Osteoporosis-Role of T Cells

The role of immune system in various bone pathologies, such as osteoporosis, osteoarthritis, and rheumatoid arthritis is now well established. This had led to the emergence of a modern field of systems biology called as osteoimmunology, an integrated research between fields of immunology and bone biology under one umbrella. Osteoporosis is one of the most common inflammatory bone loss condition with more than 200 million individuals affected worldwide. T helper (Th) cells along with various other immune cells are major players involved in bone homeostasis. In the present review, we specifically discuss the role of various defined T lymphocyte subsets (Th cells comprising Th1, Th2, Th9, Th17, Th22, regulatory T cells, follicular helper T cells, natural killer T cells, γδ T cells, and CD8⁺ T cells) in the pathophysiology of osteoporosis. The study of the specific role of immune system in osteoporosis has now been proposed by our group as “immunoporosis: the immunology of osteoporosis” with special emphasis on the role of various subsets of T lymphocytes. The establishment of this new field had been need of the hour due to the emergence of novel roles of various T cell lymphocytes in accelerated bone loss observed during osteoporosis. Activated T cells either directly or indirectly through the secretion of various cytokines and factors modulate bone health and thereby regulate bone remodeling. Several studies have summarized the role of inflammation in pathogenesis of osteoporosis but very few reports had delineated the precise role of various T cell subsets in the pathobiology of osteoporosis. The present review thus for the first time clearly highlights and summarizes the role of various T lymphocytes in the development and pathophysiology of osteoporosis, giving birth to a new field of biology termed as “immunoporosis”. This novel field will thus provide an overview of the nexus between the cellular components of both bone and immune systems, responsible for the observed bone loss in osteoporosis. A molecular insight into the upcoming and novel field of immunoporosis would thus leads to development of innovative approaches for the prevention and treatment of osteoporosis.

TH9 cell differentiation, transcriptional control and function in inflammation, autoimmune diseases and cancer

Naïve CD4⁺T cells differentiate into various T cell subsets depending on the specific cytokine environment. T_H9 cells are less well-characterized than other T cell subsets, and factors that control their development and function have only recently been identified. It is now clear that T_H9 cells play critical roles in immune-mediated diseases, including allergic airway, autoimmune and inflammatory bowel diseases, and cancer. Thus, the promotion or suppression of T_H9 cell differentiation, transcriptional control and function may provide novel treatments for clinical inflammation, autoimmune diseases and tumors.

Upregulation of IL-9 and JAK-STAT signaling pathway in children with autism

Autism spectrum disorder (ASD) gradually develops predominantly neurodevelopmental disorders, which are socially diagnosed in early childhood. Though the etiopathology of ASD is not clear, immune alteration has been suggested as autism's pathophysiological mechanism. Previous studies found that several cytokines and transcription factor activation pathways were significantly increased in ASD. IL-9 has been confirmed to play a significant role in the central nervous system (CNS). The aim of the present study was to investigate the understudied role of pro- and anti-inflammatory cytokines and the JAK-STAT signaling pathway in ASD. We examined the IL-1β, IL-4, IFN-γ, and IL-9 positive immunostaining in all cells, and CD4⁺ T cells, in ASD and normally developing control children (TD), on peripheral blood mononuclear cells (PBMCs), using flow cytometry. We explored PBMC mRNA expression levels for IL-1β, IL-4, IFN-γ, IL-9, JAK1, and STAT5, by using real-time PCR (RT-PCR). We also explored PBMC protein expression levels for IL-1β, IL-4, IL-9, pJAK1, and pSTAT5 by using western blotting. We found that the children with ASD had increased IL-1β, IL-4, IFN-γ, and IL-9 positive immunostaining in all cells, and in CD4⁺ cells, relative to the TD controls. The mRNA and protein expression for IL-1β, IL-4, IFN-γ, IL-9, JAK1, pJAK1, STAT5, and pSTAT5 were also significantly elevated in ASD relative to TD controls. These results suggested that cytokines and JAK-STAT activation signaling have an essential role in immune dysfunction in ASD.

Increased levels of the T-helper 22-associated cytokine (interleukin-22) and transcription factor (aryl hydrocarbon receptor) in patients with periodontitis are associated with osteoclast resorptive activity and severity of the disease

BACKGROUND AND OBJECTIVE

Two new T-helper (Th) phenotypes have been recently described and named Th9 and Th22 lymphocytes; however, their role in the pathogenesis of periodontitis remains unclear. This study was aimed to assess whether Th9 and Th22 lymphocytes, through interleukin (IL)-9 and IL-22 production, respectively, are associated with the severity of periodontitis and bone resorption.

MATERIAL AND METHODS

Gingival crevicular fluid samples and biopsies were obtained from patients with moderate-to-advanced chronic periodontitis and gingivitis, and healthy controls. The levels for the Th9 and Th22-associated cytokines and master-switch transcription factors Spi-B and aryl hydrocarbon receptor (AhR) were quantified by enzyme-linked immunosorbent assay, real-time reverse-transcription quantitative polymerase chain reaction and flow cytometry. In addition, the osteoclast activity in response to tissue homogenates from periodontitis and healthy samples was analyzed quantifying the number of TRAP-positive cells and areas of bone resorption pits produced, in the presence or absence of recombinant human IL-22 and anti-IL-22 neutralization antibody.

RESULTS

Higher levels of IL-22 and AhR were detected in patients with periodontitis compared with gingivitis and healthy individuals. In addition, higher levels of IL-9 and Spi-B were detected in gingivitis patients compared with periodontitis and healthy individuals. In patients with periodontitis, a significant positive correlation was detected between secreted levels of IL-22 and clinical attachment level of the sampled periodontal pockets. When osteoclasts were exposed to tissue homogenates obtained from patients with periodontitis, higher levels of resorptive activity were observed as compared with the same cells exposed to tissue homogenates obtained from healthy individuals, and this increment was dependent on the presence and neutralization of IL-22.

CONCLUSION

Increased levels of IL-22 produced by Th22 lymphocytes are associated with the pathogenesis of periodontitis, in particular, with osteoclast resorptive activity and severity of disease.

In the Shadow of Fibrosis: Innate Immune Suppression Mediated by Transforming Growth Factor-β

Transforming growth factor-β (TGFB) regulates cell proliferation, differentiation, apoptosis, and matrix homeostasis and is intimately involved in fibrosis. TGFB expression is increased in fibrotic lung diseases, such as idiopathic pulmonary fibrosis, and in chronic inflammatory conditions, such as chronic obstructive pulmonary disease and asthma. In addition to exhibiting profibrotic activities, the protein exhibits profound immune-suppressive actions involving both innate and adaptive responses, but often this aspect of TGFB biology is overlooked. Recent investigations have demonstrated that TGFB causes wide-ranging immune suppression, including blunting of pivotal early innate IFN responses. These activities permit severe virus infections, often followed by secondary bacterial infections, which may last longer, with augmented inflammation, scarring, fibrosis, and loss of lung function. Strategies to oppose TGFB actions or to enhance IFN responses may help ameliorate the detrimental consequences of infection in patients with diseases characterized by TGFB overexpression, inflammation, and fibrosis.

Retroviral Transduction and Reporter Assay: Transcription Factor Cooperation in Th9 Cell Development

Naïve CD4+ T cells differentiate into different T helper subsets in response to specific cytokine environment and transcription factors. Th9 cells are induced in response to signals from cytokines, TGF-β and IL-4. Transcription factors that are downstream of these cytokines converge to drive the development of Th9 cells. Retroviral transduction allows the genetic modification in T cells thereby helping us to better understand the molecular mechanisms that control their development as well as function. In this chapter, an optimized protocol for retroviral transduction of murine Th9 cells as well as transient transfection of Th9 cells with luciferase reporter constructs is described.

Differential human Th22-lymphocyte response triggered by Aggregatibacter actinomycetemcomitans serotypes

OBJECTIVE

In Aggregatibacter actinomycetemcomitans, different serotypes have been described based on lipopolysaccharide (LPS) antigenicity. When T lymphocytes were stimulated with these serotypes, different patterns of T-helper (Th)1 and Th17-type of immune responses were reported. Recently, two new Th phenotypes have been described and named Th9 and Th22 lymphocytes; however, their role in the pathogenesis of periodontitis remains unclear. This study aimed to investigate the potential Th9 and/or Th22 lymphocyte responses when stimulated with autologous dendritic cells infected with different A. actinomycetemcomitans serotypes.

METHODS

Monocyte-derived dendritic cells and naïve CD4⁺ T lymphocytes were obtained from healthy donors and stimulated with different serotypes of A. actinomycetemcomitans at a multiplicity of infection MOI=10² or their purified LPS (10-50ng/ml). The levels for the Th9 and Th22-associated cytokines, as well as the transcription factor master-switch genes implied in their differentiation Spi-B and AhR, were quantified by qPCR and ELISA.

RESULTS

When stimulated with the serotype b of A. actinomycetemcomitans, higher levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α were detected in dendritic cells, as well as higher levels of IL-22 and AhR were detected in T lymphocytes, when compared with stimulation with the other serotypes.

CONCLUSIONS

The serotype b of A. actinomycetemcomitans has a higher capacity of trigger Th22-type of immune response in both dendritic cells and T lymphocytes. These data allow us to suggest that, when the serotype b of A. actinomycetemcomitans is a significant part of the subgingival biofilm, the Th22 polarization might be triggered within the periodontal lesion.

Th9 cells and IL-9 in autoimmune disorders: Pathogenesis and therapeutic potentials

Naïve CD4⁺ T cells are pleiotropically divided into various T helper (Th) cell subsets, according to their pivotal roles in the regulation of immune responses. The differentiation of Th9 cells, an interleukin (IL)-9 producing subset, can be impacted by specific environmental cues, co-stimulation with transforming growth factor β (TGF-β) and IL-4, and other regulatory factors. Although IL-9 has been recognized as a classical Th2-related cytokine, recent studies have indicated that IL-9-producing cells contribute to a group of autoimmune disorders including systemic lupus erythematosus (SLE), multiple sclerosis (MS), inflammatory bowel diseases (IBD), rheumatoid arthritis (RA) and psoriasis. Studies of Th9 cells in autoimmune diseases, although in their infancy, are expected to be of growing interest in the study of potential mechanisms of cytokine regulatory pathways and autoimmune pathogenesis. Several in vitro and in vivo pre-clinical trials have been conducted to explore potential therapeutic strategies by targeting the IL-9 pathway. Specifically, anti-IL-9 monoclonal antibodies (mAbs) and IL-9 inhibitors may potentially be used for the clinical treatment of allergic diseases, autoimmune diseases or cancers. Here, we review recent research on Th9 cells and IL-9 pertaining to cell differentiation, biological characteristics and pivotal cellular inter-relationships implicated in the development of various diseases.

Generation and Expansion of T Helper 17 Lymphocytes Ex Vivo

CD4(+) T helper (Th) lymphocytes are essential elements of the complex cellular networks regulating the initiation, development, and termination of adaptive immune responses. Different independent and specialized subsets of Th cells can be distinguished based on their dedicated transcription factor and cytokine expression profiles. Th17 lymphocytes have been described about a decade ago as CD4(+) Th cells producing high quantity of IL-17A as a signature cytokine. Since their initial discovery, Th17 have drawn intense scrutiny for their dominant role in the pathogenesis of multiple autoimmune, infectious diseases and allergy. The influence of Th17 lymphocytes in cancer remains however ambiguous. The plethoric functions of Th17 may rely on the remarkable plasticity of these cells, endowed with the ability to trans-differentiate into other Th subpopulations depending on the environmental cytokine context. The possibility to generate Th17 ex vivo has facilitated the elucidation of the signals and transcription factors required for their differentiation and functions and has allowed for the evaluation of their functions following adoptive transfer in vivo. Several protocols have been developed to produce Th17 in vitro. The intent of this chapter is to provide examples of procedures for generating and expanding Th17 ex vivo.

Tumor necrosis factor receptor- associated factor 6 (TRAF6) regulation of development, function, and homeostasis of the immune system

Tumor necrosis factor receptor (TNFR)-associated factor 6 (TRAF6) is an adapter protein that mediates a wide array of protein-protein interactions via its TRAF domain and a RING finger domain that possesses non-conventional E3 ubiquitin ligase activity. First identified nearly two decades ago as a mediator of interleukin-1 receptor (IL-1R)-mediated activation of NFκB, TRAF6 has since been identified as an actor downstream of multiple receptor families with immunoregulatory functions, including members of the TNFR superfamily, the Toll-like receptor (TLR) family, tumor growth factor-β receptors (TGFβR), and T-cell receptor (TCR). In addition to NFκB, TRAF6 may also direct activation of mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K), and interferon regulatory factor pathways. In the context of the immune system, TRAF6-mediated signals have proven critical for the development, homeostasis, and/or activation of B cells, T cells, and myeloid cells, including macrophages, dendritic cells, and osteoclasts, as well as for organogenesis of thymic and secondary lymphoid tissues. In multiple cellular contexts, TRAF6 function is essential not only for proper activation of the immune system but also for maintaining immune tolerance, and more recent work has begun to identify mechanisms of contextual specificity for TRAF6, involving both regulatory protein interactions, and messenger RNA regulation by microRNAs.

Transcriptome Signatures Reveal Rapid Induction of Immune-Responsive Genes in Human Memory CD8(+) T Cells

Memory T cells (T_M) play a prominent role in protection and auto-immunity due to their ability to mount a more effective response than naïve T cells (T_N). However, the molecular mechanisms underlying enhanced functionality of T_M are not well defined, particularly in human T_M. We examined the global gene expression profiles of human CD8⁺ T_N and T_M before and after stimulation. There were 1,284, 1,373 and 1,629 differentially expressed genes between T_N and T_M at 0 hr, 4 hr and 24 hr after stimulation, respectively, with more genes expressed to higher levels in T_M. Genes rapidly up-regulated in T_N cells were largely involved in nitrogen, nucleoside and amino acid metabolisms. In contrast, those in CD8⁺ T_M were significantly enriched for immune-response-associated processes, including cytokine production, lymphocyte activation and chemotaxis. Multiple cytokines were rapidly up-regulated in T_M cells, including effector cytokines known to be produced by CD8⁺ T cells and important for their functions, as well as regulatory cytokines, both pro- and anti-inflammatory, that are not typically produced by CD8⁺ T cells. These results provide new insights into molecular mechanisms that contribute to the enhanced functionality of human CD8⁺ T_M and their prominent role in protection and auto-immunity.

p-STAT6, PU.1, and NF-κB are involved in allergen-induced late-phase airway inflammation in asthma patients

Background

Previous in vitro and animal studies demonstrated that transcription factors p-STAT6 and PU.1 are required to induce interleukin (IL)-9 secretion by T helper (Th) 9 cells. It is believed that n factor-kappaB (NF-κB) plays a role in eosinophil survival. The importance of these transcription factors in the pathogenesis of allergic asthma (AA) in humans is poorly understood. We evaluated p-STAT6 and PU.1 expression in peripheral blood Th9 cells and NF-κB expression in eosinophils during late-phase airway inflammation in AA patients.

Methods

Nineteen adults with AA and 14 adult healthy individuals (HI) were examined. Peripheral blood collected 24 h before (baseline) and 24 h after bronchial allergen challenge. CD4⁺ cells and eosinophils were isolated by high-density gradient centrifugation and magnetic separation. The percentage of Th9 cells and apoptotic eosinophils was estimated by flow cytometry. p-STAT6 and PU.1 expression was expressed as mean fluorescence intensity (MFI) in Th9 cells. NF-κB levels were expressed as MFI in peripheral blood eosinophils. Serum IL-9 and IL-5 levels were determined by enzyme-linked immunosorbent assay.

Results

At baseline, MFI of p-STAT6 and PU.1 in peripheral blood Th9 cells and MFI of NF-κB in eosinophils and, serum IL-5 and IL-9 levels were greater in AA patients (P < 0.05). Decreased eosinophil apoptosis was seen in the AA group compared with HI (P < 0.05). MFI of p-STAT6, PU.1, and NF-κB and serum levels of IL-5 and IL-9 were increased in the AA group 24 h after challenge compared with baseline (P < 0.05). In the AA group, a correlation between serum IL-9 and Th9 cells (r = 0.7, P = 0.001) and MFI of PU.1 (r = 0.6, P = 0.01) 24 h after bronchial allergen challenge was observed. A correlation between Th9 cells and MFI of p-STAT6 (r = 0.45, P = 0.03) as well as MFI of PU.1 (r = 0.5, P = 0.02) 24 h after challenge was only observed in AA patients. A correlation between the MFI of NF-κB and eosinophil apoptosis was observed in AA patients 24 h before (r = −0.46, P = 0.02) and after (r = −0.5, P = 0.02) challenge.

Discussions

p-STAT6 and PU.1 may be associated with Th9 cells and IL-9 production, whereas NF-κB and IL-5 may be associated with reduced eosinophil apoptosis in allergen-induced late-phase airway inflammation.

Trial registration

ClinicalTrials.gov NCT02214303

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-015-0119-7) contains supplementary material, which is available to authorized users.

Role of Ets Proteins in Development, Differentiation, and Function of T-Cell Subsets

Through positive selection, double-positive cells in the thymus differentiate into CD4(+) or CD8(+) T single-positive cells that subsequently develop into different types of effective T cells, such as T-helper and cytotoxic T lymphocyte cells, that play distinctive roles in the immune system. Development, differentiation, and function of thymocytes and CD4(+) and CD8(+) T cells are controlled by a multitude of secreted and intracellular factors, ranging from cytokine signaling modules to transcription factors and epigenetic modifiers. Members of the E26 transformation specific (Ets) family of transcription factors, in particular, are potent regulators of these CD4(+) or CD8(+) T-cell processes. In this review, we summarize and discuss the functions and underlying mechanisms of the Ets family members that have been characterized as involved in these processes. Ongoing research of these factors is expected to identify practical applications for the Ets family members as novel therapeutic targets for inflammation-related diseases.

Intrarenal and Urinary Th9 and Th22 Cytokine Gene Expression in Lupus Nephritis

OBJECTIVE

We studied the urinary sediment mRNA level of Th9- and Th22-related cytokines in patients with systemic lupus erythematosus (SLE).

METHODS

We quantified urinary mRNA levels of interleukin (IL) 9, IL-10, IL-22, and their corresponding transcription factors in 73 patients with active lupus nephritis, 13 patients with hypertensive nephrosclerosis (HTN), and 25 healthy subjects.

RESULTS

There was no detectable IL-9 mRNA in all samples. Patients with proliferative lupus nephritis had significantly lower urinary IL-22 mRNA levels than those with nonproliferative nephritis (2.2 ± 5.4 vs 8.6 ± 20.0 copies, p = 0.019), and urinary IL-22 mRNA level inversely correlated with the histological activity index (r = -0.427, p < 0.0001). In contrast, patients with lupus nephritis had significantly higher urinary IL-10 mRNA levels than patients with HTN (7.8 ± 18.5 vs 1.9 ± 4.0 copies, p = 0.012), and urinary IL-10 mRNA levels correlated with its intrarenal mRNA levels (r = 0.337, p = 0.004) and SLE disease activity index (r = 0.277, p = 0.018). Urinary IL-10 mRNA level was significantly lower among patients who achieved complete remission than those with partial remission or no response (4.1 ± 6.5 vs 14.1 ± 28.0 copies, p = 0.036).

CONCLUSION

Urinary IL-22 mRNA level is decreased in patients with SLE with proliferative nephritis, while urinary IL-10 mRNA levels correlates with its intrarenal mRNA level and disease activity. Urinary IL-10 mRNA levels may also predict treatment response. These results suggest that urinary mRNA levels of IL-10 and IL-22 might be used as biomarkers for assessing disease activity and risk stratification in lupus nephritis.

Transcriptional regulatory networks for CD4 T cell differentiation

CD4(+) T cells play a central role in controlling the adaptive immune response by secreting cytokines to activate target cells. Naïve CD4(+) T cells differentiate into at least four subsets, Th1Th1 , Th2Th2 , Th17Th17 , and inducible regulatory T cellsregulatory T cells , each with unique functions for pathogen elimination. The differentiation of these subsets is induced in response to cytokine stimulation, which is translated into Stat activation, followed by induction of master regulator transcription factorstranscription factors . In addition to these factors, multiple other transcription factors, both subset specific and shared, are also involved in promoting subset differentiation. This review will focus on the network of transcription factors that control CD4(+) T cell differentiation.

Chlamydial lung infection induces transient IL-9 production which is redundant for host defense against primary infection

IL-9/Th9 responses are recently found to be important for innate and adaptive immunity particularly in parasitic infections. To date, the study on the role of IL-9 in bacterial infections is limited and the reported data are contradictory. One reported function of IL-9/Th9 is to modulate Th1/Th17 responses. Since our and others’ previous work has shown a critical role of Th1 and Th17 cells in host defense against chlamydial lung infection, we here examined the role of IL-9 responses in Chlamydia muridarum (Cm) lung infection, particularly its effect on Th1 and Th17 responses and outcome infection. Our data showed quick but transient IL-9 production in the lung following infection, peaking at day 3 and back to baseline around day 7. CD4+ T cell was the major source of IL-9 production in the lung infection. Blockade of endogenous IL-9 using neutralizing antibody failed to change Interferon-γ (IFN-γ) and IL-17 production by cultured spleen mononuclear cells isolated from Cm infected mice. Similarly, in vivo neutralization of IL-9 failed to show significant effect on T cell (Th1 and Th17) and antibody responses (IgA, IgG1 and IgG2a). Consistently, the neutralization of IL-9 had no significant effect on disease process, including body weight change, bacterial burden and histopathological score. The data suggest that IL-9 production following chlamydial lung infection is redundant for host defense against the intracellular bacteria.

Peripheral blood Th9 cells and eosinophil apoptosis in asthma patients

BACKGROUND AND OBJECTIVE

Th9 cells producing interleukin (IL) 9 are novel subset of CD4+ T helper cells, which might contribute to airway inflammation in asthma. Moreover, the effect of IL-9 on eosinophils is still not fully understood. Study aim was to evaluate peripheral blood Th9 cells and eosinophil apoptosis in allergic asthma patients.

MATERIALS AND METHODS

Eighteen patients with allergic asthma and fourteen patients with allergic rhinitis were examined. Control group included sixteen healthy subjects. Allergic asthma and rhinitis patients did not use corticosteroids and antihistamines at least for 1 week. Peripheral blood eosinophils and CD4(+) cells were isolated by high density gradient centrifugation and magnetic separation. Th9 cells and apoptotic eosinophils were estimated by flow cytometer. Serum IL-9 and IL-5 concentration were determined by ELISA.

RESULTS

Peripheral blood Th9 cells percentage was increased in allergic asthma group compared with allergic rhinitis and control group (0.74%±0.32% vs. 0.19%±0.10% and 0.15%±0.08%, respectively, P<0.05). The same tendency was observed for IL-9 (P<0.01). Percentage of peripheral blood apoptotic eosinophils was decreased in allergic asthma and allergic rhinitis groups compared with control group (P<0.05). IL-9 concentration correlated with percentage of Th9 cells (r=0.64, P<0.05) and negatively with percentage of apoptotic eosinophils in allergic asthma group (r=-0.58, P<0.05). Negative correlation was found between apoptotic eosinophils count and IL-5 concentration in allergic asthma group (r=-0.76, P<0.05).

CONCLUSIONS

Patients with allergic asthma demonstrate increased peripheral blood Th9 cells count and serum IL-9, while eosinophil apoptosis is inversely related to IL-9 concentration.

Immunomodulatory effects of transforming growth factor-β in the liver

Members of the transforming growth factor-β (TGF-β) family are potent regulatory cytokines that affect multiple cell types of the immune system mediating pro-inflammatory or anti-inflammatory responses. In the liver, TGF-β is produced by a multitude of non-parenchymal liver cells including hepatic stellate cells (HSCs), liver sinusoidal endothelial cells (LSECs), Kupffer cells (KCs), and dendritic cells (DCs) as well as natural killer (NK) T cells among other hepatic lymphocytes. The effect of TGF-β on other cells is highly versatile. In concert with other soluble factors, it controls the maturation, differentiation and activity of various T cell subsets that either prevent or actuate infections, graft-versus-host reactions, immune diseases, and cancer formation. During the last decades, it became evident that some TGFB1 polymorphisms are associated with the pathogenesis of hepatic disease and that plasma TGF-β is a suitable biomarker to detect liver lesions. Moreover, since TGF-β has capacity to influence the quantity and quality of T cell subsets as well as their activity, it is obvious that a well-balanced TGF-β activity is essential for liver homeostasis. In the present review, we highlight some pivotal functions of TGF-β in hepatic immunobiology. We discuss its regulatory function on adaptive immunity, the impact on differentiation of various T cell subsets, its crosstalk with Toll like receptor signaling, and its contribution to functional impairment of the liver.

Inhibition of adaptive immunity by IL9 can be disrupted to achieve rapid T-cell sensitization and rejection of progressive tumor challenges

The tolerogenic cytokine IL9 promotes T regulatory cell function and allergic airway inflammation, but it has not been extensively studied in cancer. In this report, we used IL9-deficient mice to investigate the effects of IL9 in multiple models of breast and colon cancer development. Eliminating endogenous IL9 enabled sensitization of host T cells to tumors, leading to their early rejection without the requirement of vaccines or immunomodulatory therapies. Notably, IL9-deficient mice acquired immunologic memory, which actively protected from residual disease and tumor rechallenge, an effect linked to activation of CD8(+) T cells. Depletion of either CD8(+) or CD4(+) T cells abolished the benefits of IL9 loss to tumor control. Adoptive transfer experiments showed that T cells from tumor-rejecting IL9-deficient mice retained their effector competency in wild-type animals. Moreover, neutralizing IL9 antibody phenocopied the effects of IL9 gene deletion by slowing tumor progression in wild-type animals. Our results show the ability of IL9 to function as an inhibitor of adaptive immunity that prevents the formation of immunologic memory to a growing tumor, highlighting the potential for IL9 neutralization as a unique tool for cancer immunotherapy.

IL-9 is a key component of memory TH cell peanut-specific responses from children with peanut allergy

BACKGROUND

Differentiation between patients with peanut allergy (PA) and those with peanut sensitization (PS) who tolerate peanut but have peanut-specific IgE, positive skin prick test responses, or both represents a significant diagnostic difficulty. Previously, gene expression microarrays were successfully used to identify biomarkers and explore immune responses during PA immunotherapy.

OBJECTIVE

We aimed to characterize peanut-specific responses from patients with PA, subjects with PS, and atopic children without peanut allergy (NA children).

METHODS

A preliminary exploratory microarray investigation of gene expression in peanut-activated memory TH subsets from 3 children with PA and 3 NA children identified potential PA diagnostic biomarkers. Microarray findings were confirmed by using real-time quantitative PCR in 30 subjects (12 children with PA, 12 children with PS, and 6 NA children). Flow cytometry was used to identify the TH subsets involved.

RESULTS

Among 12,257 differentially expressed genes, IL9 showed the greatest difference between children with PA and NA children (45.59-fold change, P < .001), followed by IL5 and then IL13. Notably, IL9 allowed the most accurate classification of children with PA and NA children by using a machine-learning approach with recursive feature elimination and the random forest algorithm. Skin- and gut-homing TH cells from donors with PA expressed similar TH2- and TH9-associated genes. Real-time quantitative PCR confirmed that IL9 was the highest differentially expressed gene between children with PA and NA children (23.3-fold change, P < .01) and children with PS (18.5-fold change, P < .05). Intracellular cytokine staining showed that IL-9 and the TH2-specific cytokine IL-5 are produced by distinct TH populations.

CONCLUSION

In this study IL9 best differentiated between children with PA and children with PS (and atopic NA children). Mutually exclusive production of IL-9 and the TH2-specific cytokine IL-5 suggests that the IL-9-producing cells belong to the recently described TH9 subset.

Human TH9 cells are skin-tropic and have autocrine and paracrine proinflammatory capacity

T helper type 9 (TH9) cells can mediate tumor immunity and participate in autoimmune and allergic inflammation in mice, but little is known about the TH9 cells that develop in vivo in humans. We isolated T cells from human blood and tissues and found that most memory TH9 cells were skin-tropic or skin-resident. Human TH9 cells coexpressed tumor necrosis factor-α and granzyme B and lacked coproduction of TH1/TH2/TH17 cytokines, and many were specific for Candida albicans. Interleukin-9 (IL-9) production was transient and preceded the up-regulation of other inflammatory cytokines. Blocking studies demonstrated that IL-9 was required for maximal production of interferon-γ, IL-9, IL-13, and IL-17 by skin-tropic T cells. IL-9-producing T cells were increased in the skin lesions of psoriasis, suggesting that these cells may contribute to human inflammatory skin disease. Our results indicate that human TH9 cells are a discrete T cell subset, many are tropic for the skin, and although they may function normally to protect against extracellular pathogens, aberrant activation of these cells may contribute to inflammatory diseases of the skin.

Th17 and non-classic Th1 cells in chronic inflammatory disorders: two sides of the same coin

Th17 lymphocytes, beyond their protective role in the clearance of extracellular pathogens, also play a role in the pathogenesis of several autoimmune and inflammatory diseases, such as multiple sclerosis, rheumatoid arthritis, inflammatory bowel diseases, psoriasis and contact dermatitis. Nevertheless, they are very rare at inflammatory sites in comparison with other T cell subsets. Recently, this rarity has been explained by the finding that Th17 cells rapidly shift into the Th1 phenotype in the presence of IL-12 and/or TNF-α as well as by the fact that they possess self-regulatory mechanisms limiting their own expansion. Th17 lymphocytes that have shifted towards a Th1 phenotype seem to be particularly aggressive and more pathogenic than the Th17 unshifted cells. As a consequence, the Th17-derived Th1 cells, named non-classic Th1 cells, can become a possible target for the therapy of some inflammatory disorders. In particular, convincing evidence has recently been accumulated indicating that this subset can play a role in Crohn's disease and juvenile idiopathic arthritis. More importantly, it has been shown that TNF-α inhibitors, which are used for the treatment of such diseases, appear to be able to inhibit the transition of Th17 lymphocytes to the non-classic Th1 phenotype, and thus they possibly help to dampen inflammation and arrest disease progression. Based on this context, the definition of the soluble factors involved in the shifting from Th17 towards non-classic Th1 subset as well as the comprehension of their respective pathogenic role in human inflammatory disorders would be of great help for developing novel therapeutic strategies.

TH9 cells that express the transcription factor PU.1 drive T cell-mediated colitis via IL-9 receptor signaling in intestinal epithelial cells

The molecular checkpoints that drive inflammatory bowel diseases are incompletely understood. Here we found more T cells expressing the transcription factor PU.1 and interleukin 9 (IL-9) in patients with ulcerative colitis. In an animal model, citrine reporter mice had more IL-9-expressing mucosal T cells in experimental oxazolone-induced colitis. IL-9 deficiency suppressed acute and chronic colitis. Mice with PU.1 deficiency in T cells were protected from colitis, whereas treatment with antibody to IL-9 suppressed colitis. Functionally, IL-9 impaired intestinal barrier function and prevented mucosal wound healing in vivo. Thus, our findings suggest that the TH9 subset of helper T cells serves an important role in driving ulcerative colitis by regulating intestinal epithelial cells and that TH9 cells represent a likely target for the treatment of chronic intestinal inflammation.

Th9/IL-9 profile in human echinococcosis: their involvement in immune response during infection by Echinococcus granulosus

Th9 cells have been reported to contribute to immune responses; however, the role of Th9 cells in Echinococcus granulosus infection is unknown. This study is to determine whether Th9 cells and IL-9 are involved in human Echinococcus granulosus infection. Compared with healthy controls (HC group), the mRNA levels of PU.1, IL-9, and GATA-3 were significantly increased in patients before therapy (CE group), as revealed by qRT-PCR. Flow cytometry analysis showed that the percentages of Th9 and Th2 cells in CE group were significantly higher. The levels of IL-9, IL-4, IL-10, and TGF-β in CE group were also significantly increased, as detected by CBA assay. The percentages of Th9 and Th2 cells in CE group were positively correlated. After treatments of surgery in combination with albendazole, the PU.1 and GATA-3 mRNA levels were significantly decreased in patients after therapy (PCE group) compared with CE group. The numbers of Th9 and Th2 cells and levels of IL-9, IL-4, IL-10, and TGF-β were also significantly decreased in PCE group. In conclusion, the ratios of Th9 cells and IL-9 levels were significantly decreased after treatment, suggesting that Th9/IL-9 may be involved in immune response induced by Echinococcus granulosus infection.

Th9 cell development requires a BATF-regulated transcriptional network

T helper 9 (Th9) cells are specialized for the production of IL-9, promote allergic inflammation in mice, and are associated with allergic disease in humans. It has not been determined whether Th9 cells express a characteristic transcriptional signature. In this study, we performed microarray analysis to identify genes enriched in Th9 cells compared with other Th subsets. This analysis defined a transcriptional regulatory network required for the expression of a subset of Th9-enriched genes. The activator protein 1 (AP1) family transcription factor BATF (B cell, activating transcription factor–like) was among the genes enriched in Th9 cells and was required for the expression of IL-9 and other Th9-associated genes in both human and mouse T cells. The expression of BATF was increased in Th9 cultures derived from atopic infants compared with Th9 cultures from control infants. T cells deficient in BATF expression had a diminished capacity to promote allergic inflammation compared with wild-type controls. Moreover, mouse Th9 cells ectopically expressing BATF were more efficient at promoting allergic inflammation than control transduced cells. These data indicate that BATF is a central regulator of the Th9 phenotype and contributes to the development of allergic inflammation.