IL-9-mediated induction of eotaxin1/CCL11 in human airway smooth muscle cells

The World according to IL-9

Among the cytokines regulating immune cells, IL-9 has gained considerable attention for its ability to act on multiple cell types as a regulator of beneficial and pathologic immune responses. Yet, it is still not clearly defined how IL-9 impacts immune responses. IL-9 demonstrates a remarkable degree of tissue-specific functionality and has cellular sources that vary by tissue site and the context of the inflammatory milieu. Here, we provide perspective to summarize the biological activities of IL-9 and highlight cell type-specific roles in the immune pathogenesis of diseases. This perspective will be important in defining the diseases where targeting IL-9 as a therapeutic strategy would be beneficial and where it has the potential to complicate clinical outcomes.

Development of Adaptive Immunity and Its Role in Lung Remodeling

Asthma is characterized by airflow limitations resulting from bronchial closure, which can be either reversible or fixed due to changes in airway tissue composition and structure, also known as remodeling. Airway remodeling is defined as increased presence of mucins-producing epithelial cells, increased thickness of airway smooth muscle cells, angiogenesis, increased number and activation state of fibroblasts, and extracellular matrix (ECM) deposition. Airway inflammation is believed to be the main cause of the development of airway remodeling in asthma. In this chapter, we will review the development of the adaptive immune response and the impact of its mediators and cells on the elements defining airway remodeling in asthma.

IL-9 stimulates an anti-tumor immune response and facilitates immune checkpoint blockade in the CMT167 mouse model

OBJECTIVES

There is mounting evidence that interleukin-9 (IL-9) is associated with various cancers although its function in lung cancer remains elusive. This study aimed to elucidate the role(s) of IL-9 in lung cancer and the mechanisms involved.

MATERIALS AND METHODS

Expression of IL-9 receptor (IL-9R) in two murine lung cancer cell lines: CMT167 and Lewis lung carcinoma (LLC) were assessed and syngeneic murine lung cancer models were established. Tumor growth, intratumoral immune responses and downstream signaling pathways in tumor-bearing mice were analyzed upon IL-9 treatment. Human lung cancer cell lines A549 and H1975 were included for in vitro validation. Synergistic effects and immune responses of IL-9 in combination with anti-PD-1 were studied.

RESULTS

IL-9R expression was only detected in CMT167 but not LLC cells. IL-9 suppressed CMT167 tumor growth and enhanced anti-tumor T cell responses, both of which were absent in IL-9R-deficient LLC model and lost upon IL-9R knockdown in CMT167 model. In CMT167 tumors, while IL-9 increased CD4⁺ and CD8⁺ T cells and dendritic cells, the cytotoxic T subset was the key driver of IL-9-induced tumor suppression. Consistently, in CMT167 and A549 cells, IL-9/IL-9R signaling promoted MHC class I upregulation. Inhibition of ERK signaling abolished IL-9-mediated MHC class I upregulation in CMT167 cells. IL-9 induced expression of PD-1 and PD-L1 on CD8⁺ T lymphocytes and CMT167 cells respectively. Combined IL-9 treatment with PD-1 blockade further upregulated tumor-infiltrating CD8⁺ T cell frequencies and synergistically suppressed tumor growth in CMT167 model.

CONCLUSION

IL-9 suppresses tumor growth by promoting tumor-derived MHC class I presentation and enhancing cytotoxic T cell immunity. Expression of IL-9R might be used as a biomarker for identification of potential target population susceptible to IL-9 treatment. Our study proposes IL-9 as a promising therapeutic immunomodulatory agent that can be used in combination with PD-1 blockade in lung cancer.

Molecular cytogenetic characterization of a de novo derivative chromosome X with an unbalanced t(X;9) translocation in a fetus and literature review

Partial trisomy 9p is one of the most frequent autosome anomalies in newborn infants featured by craniofacial dysmorphism, intellectual disability and psychomotor growth. Female patients carrying monosomy Xq usually show mild symptoms due to skewed X-chromosome inactivation (XCI). Unbalanced translocation between chromosome X and chromosome 9 is rare in prenatal diagnosis. The skewed inactivation of abnormal X would spread into the extra segment of chromosome 9 presented in the der(X) leading to mild phenotypes. We reported on a fetus with high risk of trisomy 9p(13.32 Mb 9p23-p24.3 duplication)suggested by noninvasive prenatal testing (NIPT), the fetus was normal by ultrasonography. G-banding with trypsin-giemsa (GTG), copy number variations sequencing (CNV-seq) and fluorescence in situ hybridization (FISH) were carried out to delineate the nature of rearrangement. Final karyotype of the fetus was identified as 46,X,der(X)t(X;9)(q27;p23)dn. An unbalanced X-autosome translocation with a deletion of Xqter-q27.2 and a duplication of 9pter-p23 led to mild phenotypes with no obvious alteration by prenatal ultrasonography, or obvious pathological alterations after pregnancy termination.

TGF-β1 Drives Inflammatory Th Cell But Not Treg Cell Compartment Upon Allergen Exposure

TGF-β1 is known to have a pro-inflammatory impact by inducing Th9 and Th17 cells, while it also induces anti-inflammatory Treg cells (Tregs). In the context of allergic airway inflammation (AAI) its dual role can be of critical importance in influencing the outcome of the disease. Here we demonstrate that TGF-β is a major player in AAI by driving effector T cells, while Tregs differentiate independently. Induction of experimental AAI and airway hyperreactivity in a mouse model with inducible genetic ablation of the gene encoding for TGFβ-receptor 2 (Tgfbr2) on CD4⁺T cells significantly reduced the disease phenotype. Further, it blocked the induction of pro-inflammatory T cell frequencies (Th2, Th9, Th17), but increased Treg cells. To translate these findings into a human clinically relevant context, Th2, Th9 and Treg cells were quantified both locally in induced sputum and systemically in blood of allergic rhinitis and asthma patients with or without allergen-specific immunotherapy (AIT). Natural allergen exposure induced local and systemic Th2, Th9, and reduced Tregs cells, while therapeutic allergen exposure by AIT suppressed Th2 and Th9 cell frequencies along with TGF-β and IL-9 secretion. Altogether, these findings support that neutralization of TGF-β represents a viable therapeutic option in allergy and asthma, not posing the risk of immune dysregulation by impacting Tregs cells.

Interleukin-9 produced by helper T cells stimulates interleukin-8 expression in endometriosis

PROBLEM

Inflammation and immune responses play crucial roles in the development of endometriosis. Although interleukin-9 (IL-9) has a pro-inflammatory function in chronic inflammatory diseases, its function in endometriosis remains unknown. Here, we aimed to investigate the significance of IL-9 and IL-9-producing lymphocytes in endometriosis.

METHOD OF STUDY

Specimens were obtained from patients with and without endometriosis. Peritoneal fluid (PF), peripheral blood (PB), and ovarian endometrioma (OE) tissues were analyzed for the proportion of CD4⁺ IL-9⁺ lymphocytes and IL-9 concentration using flow cytometry and enzyme-linked immunosorbent assay. OE, endometrium with endometriosis (EE), and normal endometrium (NE) were analyzed for IL-9 receptor (IL-9R) expression using immunohistochemical staining. IL-9-dependent changes in Interleukin-8 (IL-8) expression in endometrial stromal cells from OE (OESCs) were evaluated using real-time PCR.

RESULTS

The proportion of CD4⁺ IL-9⁺ lymphocytes was higher in the PF, but not the PB, of patients with endometriosis than individuals without endometriosis (p < .05). However, IL-9 levels in the PF did not differ between those with and without endometriosis. We detected CD4+ IL-9+ lymphocytes in OE tissues and IL-9R in OE tissues and OESCs. In OESC culture, IL-9 significantly elevated IL-8 expression in a dose-dependent manner (p < .05), which was nullified by the addition of the anti-IL-9 receptor antibody. Furthermore, IL-9 additively stimulated IL-8 expression in the presence of TNF-α (p < .05).

CONCLUSION

Our findings show that IL-9 produced by helper T cells induces IL-8 expression, suggesting that IL-9 plays an important role in the development of endometriosis by stimulating IL-8 expression.

Enhanced IL-9 secretion by p66Shc-deficient CLL cells modulates the chemokine landscape of the stromal microenvironment

The stromal microenvironment is central to chronic lymphocytic leukemia (CLL) pathogenesis. How leukemic cells condition the stroma to enhance its chemoattractant properties remains elusive. Here, we show that mouse and human CLL cells promote the contact-independent stromal expression of homing chemokines. This function was strongly enhanced in leukemic cells from Eμ-TCL1 mice lacking the pro-oxidant p66Shc adaptor, which develop an aggressive disease with organ infiltration. We identified interleukin-9 (IL-9) as the soluble factor, negatively modulated by p66Shc, that is responsible for the chemokine-elevating activity of leukemic cells on stromal cells. IL-9 blockade in Eμ-TCL1/p66Shc-/- mice resulted in a decrease in the nodal expression of homing chemokines, which correlated with decreased leukemic cell invasiveness. IL-9 levels were found to correlate inversely with residual p66Shc in p66Shc-deficient human CLL cells (n = 52 patients). p66Shc reconstitution in CLL cells normalized IL-9 expression and neutralized their chemokine-elevating activity. Notably, high IL-9 expression in CLL cells directly correlates with lymphadenopathy, liver infiltration, disease severity, and overall survival, emerging as an independent predictor of disease outcome. Our results demonstrate that IL-9 modulates the chemokine landscape in the stroma and that p66Shc, by regulating IL-9 expression, fine tunes the ability of leukemic cells to shape the microenvironment, thereby contributing to CLL pathogenesis.

IL-9-producing T cells: potential players in allergy and cancer

IL-9-producing CD4⁺ T cells have been considered to represent a distinct T helper cell (T_H cell) subset owing to their unique developmental programme in vitro, their expression of distinct transcription factors (including PU.1) and their copious production of IL-9. It remains debatable whether these cells represent a truly unique T_H cell subset in vivo, but they are closely related to the T helper 2 (T_H2) cells that are detected in allergic diseases. In recent years, increasing evidence has also indicated that IL-9-producing T cells may have potent abilities in eradicating advanced tumours, particularly melanomas. Here, we review the latest literature on the development of IL-9-producing T cells and their functions in disease settings, with a particular focus on allergy and cancer. We also discuss recent ideas concerning the therapeutic targeting of these cells in patients with chronic allergic diseases and their potential use in cancer immunotherapy.

The emerging roles of eosinophils in mucosal homeostasis

Eosinophils are granulocytes, typically implicated as end-stage effector cells in type-II immune responses. They are capable of producing a wide array of pre-formed molecules which render them with vast potential to influence a wide variety of processes. Nonetheless, eosinophil research has traditionally focused on their role in anti-helminthic responses and pathophysiological processes in type-II immune disorders, such as allergy and asthma, where eosinophilia is a hallmark phenotype. However, a number of key studies over the past decade have placed this restricted view of eosinophil function into question, presenting additional evidence for eosinophils as critical regulators of various homeostatic processes including immune maintenance, organ development, and tissue regeneration.

Interleukin-9 Aggravates Isoproterenol-Induced Heart Failure by Activating Signal Transducer and Activator of Transcription 3 Signalling

BACKGROUND

Previous studies have demonstrated that inflammation is closely related to the occurrence and development of heart failure (HF). As an inflammation-related cytokine, interleukin (IL)-9 has been reported to be involved in the development of cardiovascular diseases. However, the role of IL-9 in HF in response to isoproterenol (ISO) stimulation has barely been explored. Thus, this study aimed to investigate whether IL-9 participates in HF and the possible associated mechanisms.

METHODS

Chronic ISO infusion was used to establish an HF model, and the IL-9 levels in mice and isolated cardiomyocytes were measured. In addition, ISO-treated mice received an injection of recombinant mouse IL-9 (rIL-9) or an antimouse IL-9 neutralizing monoclonal antibody (mAb) to investigate the effects of IL-9 on cardiac function, hypertrophy, and fibrosis.

RESULTS

IL-9 levels were significantly increased in mice and isolated cardiomyocytes after ISO treatment. Treatment with rIL-9 resulted in aggravated cardiac dysfunction and amplified cardiac hypertrophy and fibrosis, whereas treatment with the anti-IL-9 neutralizing mAb ameliorated cardiac dysfunction and reduced cardiac hypertrophy and fibrosis in ISO-treated mice. In addition, ISO infusion-induced cardiac inflammation and cardiomyocyte apoptosis was aggravated by rIL-9 but prevented by the anti-IL-9 mAb. IL-9 did not activate signal transducer and activator of transcription (STAT)1 or STAT5 but induced STAT3 phosphorylation in ISO-induced HF. Moreover, S31-201, a specific STAT3 inhibitor, nearly abolished rIL-9-induced increases in cardiac dysfunction, hypertrophy, and fibrosis in response to ISO stimulation.

CONCLUSIONS

IL-9 aggravated cardiac dysfunction and amplified cardiac hypertrophy and fibrosis in the ISO-induced HF model by activating STAT3 signalling. These data indicate that blocking IL-9 may be an attractive pharmacotherapeutic strategy for the treatment of cardiac hypertrophy and fibrosis induced by chronic β-adrenergic receptor activation to limit the progression of HF.

IL-9 Blockade Suppresses Silica-induced Lung Inflammation and Fibrosis in Mice

Recapitulative animal models of idiopathic pulmonary fibrosis (IPF) and related diseases are lacking, which inhibits our ability to fully clarify the pathogenesis of these diseases. Although lung fibrosis in mouse models is often induced by bleomycin, silica-induced lung fibrosis is more sustainable and more progressive. Therefore, in this study, we sought to elucidate the mediator(s) responsible for the pathogenesis of lung fibrosis, through the use of a mouse model of silica-induced lung fibrosis. With a single nasal administration of 16 mg of silica, lung inflammation (assessed by elevated cellular components in the BAL fluids [BALFs]) and lung fibrosis (assessed by lung histology and lung hydroxyproline levels) were induced and sustained for as long as 24 weeks. Of the mediators measured in the BALFs, IL-9 was characteristically elevated gradually, and peaked at 24 weeks after silica administration. Treatment of silica-challenged mice with anti-IL-9-neutralizing antibody inhibited lung fibrosis, as assessed by lung hydroxyproline level, and suppressed the levels of major mediators, including IL-1β, IL-6, IL-12, CCL2, CXCL1, and TNF-α in BALFs. Moreover, human lung specimens from patients with IPF have shown high expression of IL-9 in alveolar macrophages, CD4-positive cells, and receptors for IL-9 in airway epithelial cells. Collectively, these data suggest that IL-9 plays an important role in the pathogenesis of lung fibrosis in diseases such as IPF.

Butyrate Attenuates Lung Inflammation by Negatively Modulating Th9 Cells

Th9 cells orchestrate allergic lung inflammation by promoting recruitment and activation of eosinophils and mast cells, and by stimulating epithelial mucus production, which is known to be mainly dependent on IL-9. These cells share developmental pathways with induced regulatory T cells that may determine the generation of one over the other subset. In fact, the FOXP3 transcription factor has been shown to bind il9 locus and repress IL-9 production. The microbiota-derived short-chain fatty acids (SCFAs) butyrate and propionate have been described as FOXP3 inducers and are known to have anti-inflammatory properties. While SCFAs attenuate lung inflammation by inducing regulatory T cells and suppressing Th2 responses, their effects on Th9 cells have not been addressed yet. Therefore, we hypothesized that SCFAs would have a protective role in lung inflammation by negatively modulating differentiation and function of Th9 cells. Our results demonstrated that butyrate is more effective than propionate in promoting FOXP3 expression and IL-9 repression. In addition, propionate was found to negatively impact in vitro differentiation of IL-13-expressing T cells. Butyrate treatment attenuated lung inflammation and mucus production in OVA-challenged mice, which presented lower frequency of lung-infiltrated Th9 cells and eosinophils. Both Th9 cell adoptive transfer and IL-9 treatment restored lung inflammation in butyrate-treated OVA-challenged mice, indicating that the anti-inflammatory effects of butyrate may rely on suppressing Th9-mediated immune responses.

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.

Th9 lymphocytes and functions of interleukin 9 with the focus on IBD pathology

The work presents the newest knowledge on a new phenotype of T helper lymphocytes (Th9) and on Interleukin 9 (IL-9). Processes leading to transformation of naïve T lymphocyte into Th9 lymphocytes are presented, including the role of IL-4 and TGFβ signaling. Involvement of transcription factor network in production of IL-9 is described. Other cells capable of expressing IL-9 and secreting IL-9 are portrayed. Diversity of IL-9 effects caused by activation of IL-9 receptors on various types of cells is presented. Principal effects of the activation of IL-9 receptor on T-cells seem to be antiapoptotic and stimulatory which leads to enhanced defense against parasitic infection and cancer development but, from the other side, it perpetuate chronic inflammation in autoimmune diseases and allergic processes. In the last years the role of IL-9 in autoimmune diseases such as rheumatic diseases and inflammatory bowel disease gained importance since the increased expression of this cytokine has been observed in animal models of intestinal inflammation and in groups of patients with ulcerative colitis. It was also noted that neutralization of IL-9 in animal models of ulcerative colitis leads to amelioration of inflammatory process, what could have significance in the treatment of this disease in humans in the future.

Intraperitoneal administration of the anti-IL-23 antibody prevents the establishment of intestinal nematodes in mice

Previous studies have established that an increased Th-9 response creates a hostile environment for nematode parasites. Given that IL-23, a cytokine required for maintenance of the IL-17-secreting phenotype, has inhibitory effects on IL-9 production, we hypothesized that reducing circulating IL-23 by treatment with anti-IL-23 antibodies would reduce the establishment and development of parasitic intestinal nematodes. In this study, we show that animals treated with anti-IL-23 monoclonal antibodies showed a drastic reduction in the number of mouse pinworms (Aspiculuris tetraptera) recovered from the intestine (p < 0.001) at 23 days post-infection compared to the untreated animals. The cytokine levels in Peyer's patches (PP) in treated and infected animals increase the expression of interleukins such as IL-25, IL-21, and IL-9, augmenting mucus production in the crypts, and boosting chemokines, such as OX40 and CCL20 in the mucosa. Our results suggest that the Th17/Th2 regulatory mechanism provoked by the administration of the anti-IL-23 antibody prevents the implantation of the intestinal nematode in mice. The diminished inflammatory IL-17 levels alter the Th9 environment perhaps as a consequence of IL-17 inhibiting IL-9 expression. These Th9 conditions may explain the successful treatment against Inflammatory Bowel Disease (IBD) both with antibodies against IL-23 or through parasitization with nematodes.

Unveil the mysterious mask of cytokine-based immunotherapy for melanoma

Melanoma is the leading cause of death among all skin cancers and its incidence continues to rise rapidly worldwide in the past decades. The available treatment options for melanoma remain limited despite extensive clinical research. Melanoma is an immunogenic tumor and great advances in immunology in recent decades allow for the development of immunotherapeutic agents against melanoma. In recent years, immunotherapy utilizing cytokines has been particularly successful in certain cancers and holds promise for patients with advanced melanoma. In this review, an overview of the current status and emerging perspectives on cytokine immunotherapy for melanoma are discussed in details. Such a study will be helpful to unveil the mysterious mask of cytokine-based immunotherapy for melanoma.

Th9 Cells: New Member of T Helper Cell Family

T Helper cells (CD4+ T cells) constitute one of the key arms of adaptive immune responses. Differentiation of naïve CD4+ T cells into multiple subsets ensure a proper protection against multitude of pathogens in immunosufficient individual. After differentiation, T helper cells secrete specific cytokines that are critical to provide immunity against various pathogens. The recently discovered Th9 cells secrete the pleiotropic cytokine, IL-9. Although IL-9 was cloned more than 25 years ago and characterized as a Th2 cell-specific cytokine, not many studies were carried out to define the function of IL-9. This cytokine has been demonstrated to act on multiple cell types as a growth factor. After the discovery of Th9 cells as an abundant source of IL-9, renewed focus has been generated. In this chapter, I discuss the biology and development of IL-9-secreting Th9 cells. Furthermore, I highlight the role of Th9 cells and IL-9 in health and diseases.

IL-9 Signaling Pathway: An Update

Since the discovery of IL-9 almost three decades back as a growth factor, we have come a long way to understand its pleiotropic functions in the immune system. Despite its many functions, IL-9 still remains as an understudied cytokine. In the last decade, renewed emphasis has been provided to understand the biology of IL-9. Any growth factor or cytokine signals via its cognate receptor to mediate biological functions. In this chapter, we discuss the IL-9 signal transduction in different cell types, which would then exert its distinct functions.

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.

Th9 and other IL-9-producing cells in allergic asthma

Allergic asthma is a worldwide increasing chronic disease of the airways which affects more than 300 million people. It is associated with increased IgE, mast cell activation, airway hyperresponsiveness (AHR), mucus overproduction and remodeling of the airways. Previously, this pathological trait has been associated with T helper type 2 (Th2) cells. Recently, different CD4⁺ T cell subsets (Th17, Th9) as well as cells of innate immunity, like mast cells and innate lymphoid cells type 2 (ILC2s), which are all capable of producing the rediscovered cytokine IL-9, are known to contribute to this disease. Regarding Th9 cells, it is known that naïve T cells develop into IL-9-producing cells in the presence of interleukin-4 (IL-4) and transforming growth factor beta (TGFβ). Downstream of IL-4, several transcription factors like signal transducer and activator of transcription 6 (STAT6), interferon regulatory factor 4 (IRF4), GATA binding protein 3 (GATA3), basic leucine zipper transcription factor, ATF-like (BATF) and nuclear factor of activated T cells (NFAT) are activated. Additionally, the transcription factor PU.1, which is downstream of TGFβ signaling, also seems to be crucial in the development of Th9 cells. IL-9 is a pleiotropic cytokine that influences various distinct functions of different target cells such as T cells, B cells, mast cells and airway epithelial cells by activating STAT1, STAT3 and STAT5. Because of its pleiotropic functions, IL-9 has been demonstrated to be involved in several diseases, such as cancer, autoimmunity and other pathogen-mediated immune-regulated diseases. In this review, we focus on the role of Th9 and IL-9-producing cells in allergic asthma.

Potential therapeutic targets from genetic and epigenetic approaches for asthma

Asthma is a complex disorder characterised by inflammation of airway and symptoms of wheeze and shortness of breath. Allergic asthma, atopic dermatitis and allergic rhinitis are immunoglobulin E (IgE) related diseases. Current therapies targeting asthma rely on non-specific medication to control airway inflammation and prevent symptoms. Severe asthma remains difficult to treat. Genetic and genomic approaches of asthma and IgE identified many novel loci underling the disease pathophysiology. Recent epigenetic approaches also revealed the insights of DNA methylation and chromatin modification on histones in asthma and IgE. More than 30 microRNAs have been identified to have regulating roles in asthma. Understanding the pathways of the novel genetic loci and epigenetic elements in asthma and IgE will provide new therapeutic means for clinical management of the disease in future.

IL-9 signaling as key driver of chronic inflammation in mucosal immunity

Recent studies have highlighted a crucial regulatory role of the cytokine IL-9 in driving immune responses in chronic inflammatory and autoimmune diseases at mucosal surfaces. IL-9 activates various types of immune and non-immune cells carrying the membrane bound IL-9R. IL-9 signaling plays a pivotal role in controlling the differentiation and activation of these cells by inducing the Jak/STAT pathway. In particular, IL-9 induces activation of T helper cells and affects the function of various tissue resident cells such as mast cells and epithelial cells in the mucosa. Importantly, recent findings suggest that blockade of IL-9 signaling is effective in treating experimental models of autoimmune and chronic inflammatory diseases such as inflammatory bowel diseases, allergic disorders such as food allergy and asthma. Thus, blockade of IL-9 and IL-9R signaling emerges as potentially novel approach for therapy of inflammatory diseases in the mucosal immune system.

Genome-wide expression profiles identify potential targets for gene-environment interactions in asthma severity

BACKGROUND

Gene-environment interaction studies using genome-wide association study data are often underpowered after adjustment for multiple comparisons. Differential gene expression in response to the exposure of interest can capture the most biologically relevant genes at the genome-wide level.

OBJECTIVE

We used differential genome-wide expression profiles from the Epidemiology of Home Allergens and Asthma birth cohort in response to Der f 1 allergen (sensitized vs nonsensitized) to inform a gene-environment study of dust mite exposure and asthma severity.

METHODS

Polymorphisms in differentially expressed genes were identified in genome-wide association study data from the Childhood Asthma Management Program, a clinical trial in childhood asthmatic patients. Home dust mite allergen levels (<10 or ≥10 μg/g dust) were assessed at baseline, and (≥1) severe asthma exacerbation (emergency department visit or hospitalization for asthma in the first trial year) served as the disease severity outcome. The Genetics of Asthma in Costa Rica Study and a Puerto Rico/Connecticut asthma cohort were used for replication.

RESULTS

IL9, IL5, and proteoglycan 2 expression (PRG2) was upregulated in Der f 1-stimulated PBMCs from dust mite-sensitized patients (adjusted P < .04). IL9 polymorphisms (rs11741137, rs2069885, and rs1859430) showed evidence for interaction with dust mite in the Childhood Asthma Management Program (P = .02 to .03), with replication in the Genetics of Asthma in Costa Rica Study (P = .04). Subjects with the dominant genotype for these IL9 polymorphisms were more likely to report a severe asthma exacerbation if exposed to increased dust mite levels.

CONCLUSIONS

Genome-wide differential gene expression in response to dust mite allergen identified IL9, a biologically plausible gene target that might interact with environmental dust mite to increase severe asthma exacerbations in children.

IL-9 inhibits HTB-72 melanoma cell growth through upregulation of p21 and TRAIL

BACKGROUND

IL-9 is a pleiotropic cytokine produced mainly by Th9 cells. IL-9 may have an anti-proliferative role in murine melanoma, however, its effect on human melanoma is unknown.

METHODS

We examined the effects of IL-9 on proliferation and apoptosis in four human melanoma cell lines, HTB-65, HTB-72, CRL-11147, and SK-Mel-5. Clonogenic assay, PCNA staining, Quick Cell Proliferation assay, TUNEL staining and caspase-3 activity assay were used to assess proliferation and apoptosis, as appropriate.

RESULTS

We found that IL-9 decreased the percentage of colonies of HTB-72 and SK-Mel-5 cells but not that of HTB-65 or CRL-11147 cells. PCNA mRNA, PCNA+ cells, PCNA staining intensity, and the OD value of HTB-72 melanoma cells were consistently decreased in the present of IL-9. IL-9 also increased TUNEL+ cells and the relative caspase-3 activity in HTB-72 melanoma cells. We further investigated the possible molecular mechanisms using RT-PCR and immunohistochemical staining. The anti-proliferative effect of IL-9 on HTB-72 cells correlated with higher expression of anti-proliferative molecule p21. Its pro-apoptotic effect on HTB-72 cells correlated with higher expression of the pro-apoptotic molecule TRAIL.

CONCLUSIONS

IL-9 inhibits melanoma HTB-72 cell growth by upregulation of p21 and TRAIL. Understanding the interactions between IL-9 and melanoma may help direct strategies for cytokine-based immunotherapy development.

IL-9 induces IL-8 production via STIM1 activation and ERK phosphorylation in epidermal keratinocytes: A plausible mechanism of IL-9R in atopic dermatitis

BACKGROUND

IL-9 and its receptor play important roles in the pathogenesis of asthma. Its role in atopic dermatitis (AD) was examined in just a few studies, including nucleotide polymorphisms, increased transcriptional levels of IL-9 and IL-9R in diseased skin, and an association of blood IL-9 levels with clinical severity.

OBJECTIVE

Little was known about the pathophysiological regulation of IL-9/IL-9R in AD skin. We asked whether IL-9R was expressed in epidermal keratinocytes; if so, what the functional outcome, cytokine production, and signaling pathway of IL-9/IL-9R in keratinocytes are.

METHODS

We measured and compared the expression of IL-9R in skin from AD patients and controls by immunofluorescence. We also performed in vitro studies on the IL-9-treated primary keratinocytes, including flow cytometry for IL-9R expressions, Western blotting for mTOR, S6K, ERK, p38, and STAT3 activations, ELISA for cytokine levels, and immunofluorescence for STIM1.

RESULTS

We found that IL-9R was indeed expressed in keratinocytes but not in fibroblasts. Its expression in keratinocytes was enhanced by IL-4 but not by TGF-beta1. IL-9 induced a moderate production of IL-8 but not CXCL16, CCL22, TSLP, nor IL-33. IL-9 induced formation of STIM1-puncta. IL-9 induced ERK phosphorylation both dose- and time-dependently, but not mTOR, S6K, p38, or STAT3. Pretreatment with U0126 (ERK inhibitor) but not rapamycin (mTOR inhibitor) abrogated the IL-9-mediated IL-8 production. Blockage of STIM1 with BTP2 or SKF96265 abrogated ERK phosphorylation and IL-8 production induced by IL-9.

CONCLUSION

This study represents the first to show the regulation of the IL-9-STIM1-ERK-IL-8 axis in keratinocyte, and how the axis might play an important role in the pathophysiology of AD.

T-helper cell-mediated factors in drug-induced liver injury

Drug-induced liver injury (DILI) leads to a large burden on the healthcare system due to its potential morbidity and mortality. The key for predicting and preventing DILI is to understand the underlying mechanisms. Hepatic inflammation is one of the most common features of DILI. The inflammation can be attributed to the innate immune response. The adaptive immune system is also affected by the innate immune response resulting in liver damage. T-helper cells are important regulators of acquired immunity. T-helper cell-mediated immune responses play pivotal roles in the pathogenesis of a variety of liver disorders. This review summarizes recent advances in the T-helper cell-mediated factors in DILI and potential mechanisms, which may lead to a better understanding of DILI.

Therapeutic potential of combined anti-IL-1β IgY and anti-TNF-α IgY in guinea pigs with allergic rhinitis induced by ovalbumin

We have previously demonstrated that anti-IL-1β immunoglobulin yolk(IgY) inhibits pathological responses in allergic asthma guinea pigs induced by ovalbumin(OVA). This study aims to determine whether the combined blockade of IL-1β and TNF-α can more effectively inhibit allergic inflammation in allergic rhinitis(AR) guinea pigs induced by OVA. Healthy guinea pigs treated with saline were used as the healthy control. The AR guinea pigs induced by OVA were randomly divided into (1) the AR model group containing negative control animals treated with intranasal saline; (2) the 0.1% non-specific IgY treatment group treated with non-specific IgY; (3) the 0.1% anti-TNF-α IgY treatment group treated with 0.1% anti-TNF-α IgY; (4) the 0.1% anti-IL-1β IgY treatment group treated with 0.1% anti-IL-1β IgY; (5) the 0.1% combined anti-IL-1β IgY and anti-TNF-α IgY treatment group treated with 0.1% combined anti-IL-1β IgY and anti-TNF-α IgY; and (6) the fluticasone propionate treatment group treated with fluticasone propionate. Cytokines were measured using an enzyme-linked immunosorbent assay. The results showed that IL-1β, IL-5, IL-9, IL-13, IL-18, IL-22, IL-33, TNF-α, TGF-β1 and OVA-specific IgE levels in the peripheral blood (PB) and nasal lavage fluid (NLF) significantly decreased at 2h, 4h or 8h in the 0.1% combined anti-IL-1β IgY and anti-TNF-α IgY treatment group compared to the AR model group and the 0.1% non-specific IgY treatment group (P<0.05). The data suggest that blockade of IL-1β and TNF-α by intranasal instillation of combined anti-IL-1β IgY and anti-TNF-α IgY could be a potential alternative strategy for preventing and treating allergic rhinitis.

Roles of interleukin-9 in the growth and cholecystokinin-induced intracellular calcium signaling of cultured interstitial cells of Cajal

Interstitial cells of Cajal (ICC) are pacemaker cells in the gastrointestinal (GI) tract and loss of ICC is associated with many GI motility disorders. Previous studies have shown that ICC have the capacity to regenerate or restore, and several growth factors are critical to their growth, maintenance or regeneration. The present study aimed to investigate the roles of interleukin-9 (IL-9) in the growth, maintenance and pacemaker functions of cultured ICC. Here, we report that IL-9 promotes proliferation of ICC, and culturing ICC with IL-9 enhances cholecystokinin-8-induced Ca²⁺ transients, which is probably caused by facilitating maintenance of ICC functions under culture condition. We also show co-localizations of cholecystokinin-1 receptor and IL-9 receptor with c-kit by double-immunohistochemical labeling. In conclusion, IL-9 can promote ICC growth and help maintain ICC functions; IL-9 probably performs its functions via IL-9 receptors on ICC.

Tailored immune responses: novel effector helper T cell subsets in protective immunity

Differentiation of naïve CD4⁺ cells into functionally distinct effector helper T cell subsets, characterised by distinct "cytokine signatures," is a cardinal strategy employed by the mammalian immune system to efficiently deal with the rapidly evolving array of pathogenic microorganisms encountered by the host. Since the T(H)1/T(H)2 paradigm was first described by Mosmann and Coffman, research in the field of helper T cell biology has grown exponentially with seven functionally unique subsets having now been described. In this review, recent insights into the molecular mechanisms that govern differentiation and function of effector helper T cell subsets will be discussed in the context of microbial infections, with a focus on how these different helper T cell subsets orchestrate immune responses tailored to combat the nature of the pathogenic threat encountered.

IL-9 regulates allergen-specific Th1 responses in allergic contact dermatitis

The cytokine IL-9, derived primarily from T-helper 9 (Th9) lymphocytes, promotes expansion of the Th2 subset and is implicated in the mechanisms of allergic asthma. We hypothesize that IL-9 also has a role in human allergic contact dermatitis (ACD). To investigate this hypothesis, skin biopsy specimens of positive patch-test sites from non-atopic patients were assayed using quantitative PCR and immunohistochemistry. The cytokines IFN-γ, IL-4, IL-17A, IL-9, and PU.1, a Th9 associated transcription factor, were elevated when compared with paired normal skin. Immunohistochemistry on ACD skin biopsies identified PU.1+ CD3+ and PU.1+ CD4+ cells, consistent with Th9 lymphocytes, in the inflammatory infiltrate. Peripheral blood mononuclear cells from nickel-allergic patients, but not nonallergic controls, show significant IL-9 production in response to nickel. Blocking studies with mAbs to HLA-DR (but not HLA-A, -B, -C) or chloroquine significantly reduced this nickel-specific IL-9 production. In addition, blockade of IL-9 or IL-4 enhanced allergen-specific IFN-γ production. A contact hypersensitivity model using IL-9(-/-) mice shows enhanced Th1 lymphocyte immune responses, when compared with wild-type mice, consistent with our human in vitro data. This study demonstrates that IL-9, through its direct effects on Th1 and ability to promote IL-4 secretion, has a regulatory role for Th1 lymphocytes in ACD.

Th9 Cells Drive Host Immunity against Gastrointestinal Worm Infection

Type 2 inflammatory cytokines, including interleukin-4 (IL-4), IL-5, IL-9, and IL-13, drive the characteristic features of immunity against parasitic worms and allergens. Whether IL-9 serves an essential role in the initiation of host-protective responses is controversial, and the importance of IL-9- versus IL-4-producing CD4⁺ effector T cells in type 2 immunity is incompletely defined. Herein, we generated IL-9-deficient and IL-9-fluorescent reporter mice that demonstrated an essential role for this cytokine in the early type 2 immunity against Nippostrongylus brasiliensis. Whereas T helper 9 (Th9) cells and type 2 innate lymphoid cells (ILC2s) were major sources of infection-induced IL-9 production, the adoptive transfer of Th9 cells, but not Th2 cells, caused rapid worm expulsion, marked basophilia, and increased mast cell numbers in Rag2-deficient hosts. Taken together, our data show a critical and nonredundant role for Th9 cells and IL-9 in host-protective type 2 immunity against parasitic worm infection.

A randomized, controlled trial to evaluate the effect of an anti-interleukin-9 monoclonal antibody in adults with uncontrolled asthma

BACKGROUND

Preclinical studies suggest that interleukin-9 may be a central mediator in the development and maintenance of airway inflammation in asthma. The aim of this study was therefore to evaluate the effects of MEDI-528, an anti-interleukin-9 monoclonal antibody, in adults with confirmed uncontrolled moderate-to-severe asthma.

METHODS

In this prospective double-blind, multicenter, parallel-group study, 329 subjects were randomized (1:1:1:1) to subcutaneous placebo or MEDI-528 (30, 100, 300 mg) every 2 weeks for 24 weeks, in addition to their usual asthma medications. The primary endpoint was change in mean Asthma Control Questionnaire-6 (ACQ-6) score at week 13. Secondary endpoints included weighted asthma exacerbation rates and pre-bronchodilator forced expiratory volume in 1 second (FEV1) at weeks 13 and 25, as well as Asthma Quality of Life Questionnaire scores at weeks 12 and 25 and the safety of MEDI-528 throughout the study period. The primary endpoint was analyzed using analysis of covariance.

RESULTS

The study population (n = 327) was predominantly female (69%) with a mean age of 43 years (range 18-65). The mean (SD) baseline ACQ-6 score for placebo (n = 82) and combined MEDI-528 (n = 245) was 2.8 (0.7) and 2.8 (0.8); FEV1 % predicted was 70.7% (15.9) and 71.5% (16.7). Mean (SD) change from baseline to week 13 in ACQ-6 scores for placebo vs combined MEDI-528 groups was -1.2 (1.0) vs -1.2 (1.1) (p = 0.86). Asthma exacerbation rates (95% CI) at week 25 for placebo vs MEDI-528 were 0.58 (0.36-0.88) vs 0.49 (0.37-0.64) exacerbations/subject/year (p = 0.52). No significant improvements in FEV1 % predicted were observed between the placebo and MEDI-528 groups. Adverse events were comparable for placebo (82.9%) and MEDI-528 groups (30 mg, 76.5%; 100 mg, 81.9%; 300 mg, 85.2%). The most frequent were asthma (placebo vs MEDI-528, 30.5% vs 33.5%), upper respiratory tract infection (14.6% vs 17.1%), and headache (9.8% vs 9.8%).

CONCLUSIONS

The addition of MEDI-528 to existing asthma controller medications was not associated with any improvement in ACQ-6 scores, asthma exacerbation rates, or FEV1 values, nor was it associated with any major safety concerns.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00968669.

Neuronal chemorepellent Semaphorin 3E inhibits human airway smooth muscle cell proliferation and migration

BACKGROUND

Chronic airway diseases, including asthma, are characterized by increased airway smooth muscle (ASM) mass that is due in part to growth factor-mediated ASM cell proliferation and migration. However, the molecular mechanisms underlying these effects are not completely understood. Semaphorin 3E (Sema3E) has emerged as an essential mediator involved in cell migration, proliferation, and angiogenesis, although its role in ASM cell function is not investigated.

OBJECTIVES

We sought to determine the expression of Sema3E receptor, plexinD1, in human ASM cells (HASMCs); effect of Sema3E on basal and platelet-derived growth factor (PDGF)-induced proliferation and migration; and underlying signaling pathways.

METHODS

Expression of plexinD1 in HASMCs was studied with RT-PCR, immunostaining, and flow cytometry. The effect of Sema3E on HASMC proliferation and migration was evaluated by 5-ethynyl-2'-deoxyuridine (EdU) incorporation, cell count, and Boyden chamber assay. Sema3E-mediated intracellular signaling was investigated with fluorescent microscopy, flow cytometry, Rac1 activation, and Western blot analysis.

RESULTS

HASMCs from healthy persons expressed plexinD1 more than HASMCs from asthmatic patients. Sema3E increased plexinD1 expression in HASMCs from asthmatic patients. Recombinant Sema3E inhibited PDGF-mediated HASMC proliferation and migration, which was associated with F-actin depolymerization, suppression of PDGF-induced Rac1 guanosine triphosphatase activity, and Akt and extracellular signal-regulated kinase 1 and 2 phosphorylation. Bronchial biopsies from patients with mild asthma displayed immunoreactivity of plexinD1, suggesting the potential in vivo role of Sema3E-PlexinD1 axis in HASMC function.

CONCLUSION

This study provides the first evidence that Sema3E receptor is expressed and plays functional roles in HASMCs. Our data suggest a regulatory role of Sema3E in PDGF-mediated proliferation and migration, leading to downregulation of ASM remodeling.

Th9 cells: differentiation and disease

CD4(+) T-helper cells regulate immunity and inflammation through the acquisition of potential to secrete specific cytokines. The acquisition of cytokine-secreting potential, in a process termed T-helper cell differentiation, is a response to multiple environmental signals including the cytokine milieu. The most recently defined subset of T-helper cells are termed Th9 and are identified by the potent production of interleukin-9 (IL-9). Given the pleiotropic functions of IL-9, Th9 cells might be involved in pathogen immunity and immune-mediated disease. In this review, I focus on recent developments in understanding the signals that promote Th9 differentiation, the transcription factors that regulate IL-9 expression, and finally the potential roles for Th9 cells in immunity in vivo.

Distinct chemokine receptor axes regulate Th9 cell trafficking to allergic and autoimmune inflammatory sites

Migration of Th cells to peripheral sites of inflammation is essential for execution of their effector function. The recently described Th9 subset characteristically produces IL-9 and has been implicated in both allergy and autoimmunity. Despite this, the migratory properties of Th9 cells remain enigmatic. In this study, we examined chemokine receptor usage by Th9 cells and demonstrate, in models of allergy and autoimmunity, that these cells express functional CCR3, CCR6, and CXCR3, chemokine receptors commonly associated with other, functionally opposed effector Th subsets. Most Th9 cells that express CCR3 also express CXCR3 and CCR6, and expression of these receptors appears to account for the recruitment of Th9 cells to disparate inflammatory sites. During allergic inflammation, Th9 cells use CCR3 and CCR6, but not CXCR3, to home to the peritoneal cavity, whereas Th9 homing to the CNS during experimental autoimmune encephalomyelitis involves CXCR3 and CCR6 but not CCR3. To our knowledge, these data provide the first insights into regulation of Th9 cell trafficking in allergy and autoimmunity.

Fumaric acid attenuates the eotaxin-1 expression in TNF-α-stimulated fibroblasts by suppressing p38 MAPK-dependent NF-κB signaling

Eotaxin-1 is a potent chemoattractant for eosinophils and a critical mediator during the development of eosinophilic inflammation. Fumaric acid is an intermediate product of the citric acid cycle, which is source of intracellular energy. Although fumaric acid ameliorates psoriasis and multiple sclerosis, its involvement in eotaxin-1-mediated effects has not been assessed. In this study, we investigated the effects of fumaric acid on eotaxin-1 expression in a mouse fibroblast cell line. We found that fumaric acid significantly inhibited tumor necrosis factor-α (TNF-α-induced eotaxin-1 expression. This fumaric acid effect was mediated through the inhibition of p38 mitogen-activated protein kinase (MAPK)-dependent nuclear factor (NF)-κB signaling. We also found that fumaric acid operates downstream of MEKK3 during TNF-α-induced NF-κB signaling, which upregulated eotaxin-1 expression. In addition, fumaric acid attenuated expression of CC-chemokine receptor 3 (CCR3), an eotaxin-1 receptor, and adhesion molecules that play important roles in eosinophil binding to induce allergic inflammation. Taken together, these findings indicate that inhibiting TNF-α-induced eotaxin-1 expression by fumaric acid occurs primarily through suppression of NF-κB signaling, which is mediated by inhibiting p38 MAPK and suggest that fumaric acid may be used as a complementary treatment option for eotaxin-1-mediated diseases.

The Human Pseudoautosomal Region (PAR): Origin, Function and Future

The pseudoautosomal regions (PAR1 and PAR2) of the human X and Y chromosomes pair and recombine during meiosis. Thus genes in this region are not inherited in a strictly sex-linked fashion. PAR1 is located at the terminal region of the short arms and PAR2 at the tips of the long arms of these chromosomes. To date, 24 genes have been assigned to the PAR1 region. Half of these have a known function. In contrast, so far only 4 genes have been discovered in the PAR2 region. Deletion of the PAR1 region results in failure of pairing and male sterility. The gene SHOX (short stature homeobox-containing) resides in PAR1. SHOX haploinsufficiency contributes to certain features in Turner syndrome as well as the characteristics of Leri-Weill dyschondrosteosis. Only two of the human PAR1 genes have mouse homologues. These do not, however, reside in the mouse PAR1 region but are autosomal. The PAR regions seem to be relics of differential additions, losses, rearrangements and degradation of the X and Y chromosome in different mammalian lineages. Marsupials have three homologues of human PAR1 genes in their autosomes, although, in contrast to mouse, do not have a PAR region at all. The disappearance of PAR from other species seems likely and this region will only be rescued by the addition of genes to both X and Y, as has occurred already in lemmings. The present review summarizes the current understanding of the evolution of PAR and provides up-to-date information about individual genes residing in this region.

A brief history of IL-9

IL-9 was first described in the late 1980s as a member of a growing number of cytokines that had pleiotropic functions in the immune system. Although many biological functions have been attributed to IL-9, it remains an understudied cytokine. A resurgence of interest in IL-9 has been spurred by recent work demonstrating a role for IL-9 in regulating inflammatory immunity and defining the transcription factors that activate the Il9 gene in cells that most efficiently produce IL-9. In this review, we summarize the characterization of IL-9 biological activities, highlight roles for the cytokine that are clearly defined, and outline questions regarding IL-9 functions that still require further exploration.

Thymic stromal lymphopoietin receptor-mediated IL-6 and CC/CXC chemokines expression in human airway smooth muscle cells: role of MAPKs (ERK1/2, p38, and JNK) and STAT3 pathways

Thymic stromal lymphopoietin (TSLP) plays a pivotal role in allergic diseases such as asthma, chronic obstructive pulmonary disease, and atopic dermatitis. Enhanced TSLP expression has been detected in asthmatic airways that correlated with both the expression of Th2-attracting chemokines and with disease severity. Although cumulative evidence suggests that human airway smooth muscle (HASM) cells can initiate or perpetuate the airway inflammation by secreting a variety of inflammatory cell products such as cytokines and chemokines, the role of TSLP in this pathway is not known. In the current study, we sought to investigate whether HASM cells express the TSLP receptor (TSLPR) and whether it is functional. We first demonstrated that primary HASM cells express the transcript and protein of both TSLPR subunits (TSLPR and IL-7Ralpha). Functionally, TSLPR-mediated HASM activation induced a significant increase in CXC (IL-8/CXCL8), CC (eotaxin-1/CCL11) chemokines, and proinflammatory cytokine IL-6 expression. Furthermore, using biochemical and genetic approaches, we found that TSLP-induced proinflammatory gene expression in HASM involved the transcriptional mechanisms, MAPKs (ERK1/2, p38, and JNK), and STAT3 activation. Finally, TSLPR immunoreactivity in bronchial sections from mild allergic asthmatics suggested the potential in vivo TSLP targeting of HASM. Altogether, our data suggest that the TSLPR-mediated HASM activation induces proinflammatory cytokine and chemokines release that may facilitate inflammatory immune cells recruitment in airways. In addition, it may be inferred that TSLPR is involved in the pathogenesis of allergic asthma through the activation of HASM cells by TSLP.

IL-9 induces CCL11 expression via STAT3 signalling in human airway smooth muscle cells

BACKGROUND

Previous findings support the concept that IL-9 may play a significant role in mediating both pro-inflammatory and changes in airway responsiveness that characterizes the atopic asthmatic state. We previously demonstrated that human airway smooth muscle (ASM) cells express a functional IL-9R that mediate CCL11 expression. However, the signaling pathway governing this effect is not well understood.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, we showed that IL-9 mediated CCL11 expression in ASM cells does not rely on STAT6 or STAT5 but on STAT3 pathway. IL-9 induced rapid STAT3 activation in primary ASM cells that was not observed in case of STAT6 or STAT5. STAT3 binding to CCL11 promoter was also observed in vivo upon IL-9 stimulation of ASM cells. Disruption of STAT3 activity with SH2 domain binding inhibitory peptide results in significant reduction of IL-9 mediated CCL11 promoter activity. DN STAT3beta over-expression in ASM cells, but not Ser 727 STAT3 or STAT6 DN, abolishes IL-9 mediated CCL11 promoter activity. Finally, STAT3 but not STAT6 silenced ASM cells showed significant reduction in IL-9 mediated CCL11 promoter activity and mRNA expression.

CONCLUSION/SIGNIFICANCE

Taken together, our results indicate that IL-9 mediated CCL11 via STAT3 signalling pathway may play a crucial role in airway inflammatory responses.

Th9 and allergic disease

Helper CD4(+) T-cell subsets have improved our understanding of adaptive immunity in humans and in animal models of disease. These include T helper type 1 (Th1), Th2 and the interleukin-17 (IL-17) -producing population 'Th17'. Th2 cells have been described as orchestrating the immune response in allergic disease based on studies with patient samples and animal models. The cytokine IL-9 has largely been regarded as a Th2 cytokine that makes multifocal contributions to allergic disease. Recent data suggest that under certain conditions relevant to chronic disease (IL-4 and transforming growth factor-beta), a distinct population of IL-9-producing 'Th9' helper T cells can exist. The contribution of Th9 cells in allergic disease is currently unknown, and this review will propose a model for how these cells may regulate chronic allergic inflammation.

Two first-in-human, open-label, phase I dose-escalation safety trials of MEDI-528, a monoclonal antibody against interleukin-9, in healthy adult volunteers

BACKGROUND

Interleukin-9 (IL-9) is involved in pathogenic aspects of the asthmatic response, including induction of the proliferation of T-helper type 2 lymphocytes, mucus production, and mast-cell differentiation, proliferation, and recruitment to the lung. In preclinical studies in mice, inhibition of IL-9 through neutralizing monoclonal antibody (mAb) treatment partially reduced airway hyperresponsiveness and mast-cell progenitor migration to the lung.

OBJECTIVE

The goal of the present studies was to determine the safety and pharmacokinetic profiles and immunogenicity of MEDI-528, a humanized immunoglobulin G1k anti-IL-9 mAb, in healthy adult volunteers.

METHODS

In separate open-label, Phase I dose-escalation studies, single doses of MEDI-528 0.3, 1.0, 3.0, or 9.0 mg/kg were administered as an intravenous infusion (20 mg/min administered over 1-40 minutes, depending on dose) and by subcutaneous injection. All subjects were followed for 84 days. Any laboratory test value outside the normal reference range was considered an adverse event (AE).

RESULTS

Twenty-four subjects were enrolled in the intravenous study, and 29 subjects were enrolled in the subcutaneous study. No deaths or serious or severe AEs occurred in either study. The most frequently reported AEs in the intravenous study were laboratory test abnormalities; the most frequently reported AEs in the subcutaneous study were pharyngolaryngeal pain, palpable lymph nodes, and laboratory test abnormalities. The single-dose pharmacokinetics of MEDI-528 were linear and dose proportional over the dose range studied with both routes of administration. The mean t((1/2)) after intravenous administration was approximately 26 days (range, 25-28 days); the mean t((1/2)) after subcutaneous administration ranged from 33 to 87 days across doses. A low titer (1:80) of antibodies to MEDI-528 was detected on day 84 in a single volunteer receiving intravenous MEDI-528 3.0 mg/kg. No antibody titers were detected in any of the volunteers receiving subcutaneous MEDI-528.

CONCLUSIONS

Administered intravenously or subcutaneously, MEDI-528 had an acceptable safety profile and exhibited linear pharmacokinetics over the dose range studied in healthy adults in these Phase I studies. The findings support further investigation of MEDI-528 in multiple-dose trials in patients with asthma. ClinicalTrials.gov Identification numbers: NCT00192296 (intravenous study); NCT00116168 (subcutaneous study).

Th2 cells as targets for therapeutic intervention in allergic bronchial asthma

Th2 cells play a central role in the pathogenesis of allergic bronchial asthma, since each of their characteristic cytokines such as IL-4, IL-5, IL-9 and IL-13 contributes to hallmarks of this disease, including airway eosinophilia, increased mucus production, production of allergen-specific IgE and development of airway hyper-responsiveness. Therefore, these cells are predisposed as target cells for therapeutic intervention. Experimental approaches targeted Th2-type effector cytokines, Th2-cell recruitment and Th2-cell development. Another strategy uses the immunomodulatory potential of tolerance-inducing cytokines such as IL-10 or of cytokines such as IL-12, IL-18 and IFN-gamma that are able to induce a counterbalancing Th1 immune response.

T(H)2 cytokines modulate the IL-9R expression on human neutrophils

Interleukin (IL)-9 is associated with key pathological features of asthma such as airway hyperresponsiveness, bronchoconstriction and mucus production. Inflammatory responses mediated by IL-9 rely on the expression of the IL-9R which has been reported on lung epithelial cells, T lymphocytes and recently on airway granulocyte infiltrates. In this study, we assessed the regulatory and constitutive cell surface expression of the IL-9Ralpha in unfractionated and purified human neutrophils from atopic asthmatics, atopic non-asthmatics and healthy normal controls. We demonstrate that T(H)2 cytokines (IL-4 or IL-13) and granulocyte macrophage-colony stimulating factor (GM-CSF) up-regulated mRNA and cell surface expression levels of the IL-9Ralpha in primary human and HL-60 differentiated neutrophils. Pharmacological inhibition of NF-kappaB did not affect T(H)2-mediated IL-9Ralpha expression in human neutrophils although IFN-gamma and IL-10 down-regulated IL-9Ralpha expression when co-incubated with IL-4, IL-13 or GM-CSF. Collectively, our results reveal a regulatory function for IFN-gamma and IL-10 on modulating the inducible IL-9Ralpha expression levels on peripheral blood neutrophils by T(H)2 cytokines.

Transcriptional regulation of cytokine function in airway smooth muscle cells

The immuno-modulatory properties of airway smooth muscle have become of increasing importance in our understanding of the mechanisms underlying chronic inflammation and structural remodeling of the airway wall in asthma and chronic obstructive pulmonary disease (COPD). ASM cells respond to many cytokines, growth factors and lipid mediators to produce a wide array of immuno-modulatory molecules which may in turn orchestrate and perpetuate the disease process in asthma and COPD. Despite numerous studies of the cellular effects of cytokines on cultured ASM, few have identified intracellular signaling pathways by which cytokines modulate or induce these cellular responses. In this review we provide an overview of the transcriptional mechanisms as well as intracellular signaling pathways regulating cytokine functions in ASM cells. The recent discovery of toll-like receptors in ASM cells represents a significant development in our understanding of the immuno-modulatory capabilities of ASM cells. Thus, we also review emerging evidence of the inflammatory response to toll-like receptor activation in ASM cells.

Mechanistic systems biology of inflammatory gene expression in airway smooth muscle as tool for asthma drug development

There is compelling evidence that airway smooth muscle cells may function as inflammatory cells in the airway system by producing multiple inflammatory cytokines in response to a large array of external stimuli such as acetylcholine, bradykinin, inflammatory cytokines, and toll-like receptor activators. However, how multiple extracellular stimuli interact in the regulation of inflammatory gene expression in an airway smooth muscle cell remains poorly understood. This review addresses the mechanistic systems biology of inflammatory gene expression in airway smooth muscle by discussing: a) redundancy underlying multiple stimulus-product relations in receptor-mediated inflammatory gene expression, and their regulation by convergent activation of Erk1/2 mitogen-activated protein kinase (MAPK), b) Erk1/2 MAPK-dependent induction of phosphatase expression as a negative feedback mechanism in the robust maintenance of inflammatory gene expression, and c) cyclooxygenase 2-dependent regulation of the differential temporal dynamics of early and late inflammatory gene expression. It is becoming recognized that a single-target approach is unlikely to be effective for the treatment of inflammatory airway diseases because airway inflammation is a result of complex interactions among multiple inflammatory mediators and cells types in the airway system. Understanding the mechanistic systems biology of inflammatory gene expression in airway smooth muscle and other cell types in the airway system may lead to the development of multi-target drug regimens for the treatment of inflammatory airway diseases such as asthma.

CD11b+ myeloid cells are the key mediators of Th2 cell homing into the airway in allergic inflammation

STAT6-mediated chemokine production in the lung is required for Th2 lymphocyte and eosinophil homing into the airways in allergic pulmonary inflammation, and thus is a potential therapeutic target in asthma. However, the critical cellular source of STAT6-mediated chemokine production has not been defined. In this study, we demonstrate that STAT6 in bone marrow-derived myeloid cells was sufficient for the production of CCL17, CCL22, CCL11, and CCL24 and for Th2 lymphocyte and eosinophil recruitment into the allergic airway. In contrast, STAT6 in airway-lining cells did not mediate chemokine production or support cellular recruitment. Selective depletion of CD11b(+) myeloid cells in the lung identified these cells as the critical cellular source for the chemokines CCL17 and CCL22. These data reveal that CD11b(+) myeloid cells in the lung help orchestrate the adaptive immune response in asthma, in part, through the production of STAT6-inducible chemokines and the recruitment of Th2 lymphocytes into the airway.