Il-9 stimulates release of chemotactic factors from human bronchial epithelial cells

A reappraisal of IL-9 in inflammation and cancer

While much is known about the functional effects of type 2 cytokines interleukin (IL)-4, IL-5 and IL-13 in homeostasis and disease, we still poorly understand the functions of IL-9. Chronic inflammation seen in allergic diseases, autoimmunity and cancer is however frequently accompanied by overproduction of this elusive type 2 cytokine. Initially identified as a T cell and mast cell growth factor, and later as the hallmark cytokine defining TH9 cells, we now know that IL-9 is produced by multiple innate and adaptive immune cells. Recent evidence suggests that IL-9 controls discrete aspects of the allergic cascade, cellular responses of immune and stromal cells, cancer progression, tolerance and immune escape. Despite functioning as a pleiotropic cytokine in mucosal environments, like the lungs, the direct and indirect cellular targets of IL-9 are still not well characterized. Here, we discuss IL-9's cellular senders and receivers, focusing on asthma and cancer. Moreover, we review current research directions and the outlook of targeted therapy centered around the biology of IL-9.

Biodiesel feedstock determines exhaust toxicity in 20% biodiesel: 80% mineral diesel blends

To address climate change concerns, and reduce the carbon footprint caused by fossil fuel use, it is likely that blend ratios of renewable biodiesel with commercial mineral diesel fuel will steadily increase, resulting in biodiesel use becoming more widespread. Exhaust toxicity of unblended biodiesels changes depending on feedstock type, however the effect of feedstock on blended fuels is less well known. The aim of this study was to assess the impact of biodiesel feedstock on exhaust toxicity of 20% blended biodiesel fuels (B20). Primary human airway epithelial cells were exposed to exhaust diluted 1/15 with air from an engine running on conventional ultra-low sulfur diesel (ULSD) or 20% blends of soy, canola, waste cooking oil (WCO), tallow, palm or cottonseed biodiesel in diesel. Physico-chemical exhaust properties were compared between fuels and the post-exposure effect of exhaust on cellular viability and media release was assessed 24 h later. Exhaust properties changed significantly between all fuels with cottonseed B20 being the most different to both ULSD and its respective unblended biodiesel. Exposure to palm B20 resulted in significantly decreased cellular viability (96.3 ± 1.7%; p < 0.01) whereas exposure to soy B20 generated the greatest number of changes in mediator release (including IL-6, IL-8 and TNF-α, p < 0.05) when compared to air exposed controls, with palm B20 and tallow B20 closely following. In contrast, canola B20 and WCO B20 were the least toxic with only mediators G-CSF and TNF-α being significantly increased. Therefore, exposure to palm B20, soy B20 and tallow B20 were found to be the most toxic and exposure to canola B20 and WCO B20 the least. The top three most toxic and the bottom three least toxic B20 fuels are consistent with their unblended counterparts, suggesting that feedstock type greatly impacts exhaust toxicity, even when biodiesel only comprises 20% of the fuel.

Changes in IL-16 Expression in the Ovary during Aging and Its Potential Consequences to Ovarian Pathology

Aging in females is not only associated with the changes in hormonal status but is also responsible for dysregulation of immune functions in various organs including ovaries. The goal of this study was to determine whether the expression of interleukin 16 (IL-16), a proinflammatory and chemoattractant cytokine, changes during ovarian aging, to determine factors involved in such changes in IL-16 expression, and to examine if changes in IL-16 expression during aging predisposes the ovary to pathologies. Ovarian tissues from premenopausal women (30-50 years old), women at early menopause (55-59 years old), and late menopause (60-85 years old) were used. In addition, tumor tissues from patients with ovarian high-grade serous carcinoma at early stage (n = 5) were also used as reference tissue for comparing the expression of several selected markers in aging ovaries. The expression of IL-16, frequency of macrophages (a source of IL-16) and expression of microRNA (miR) 125a-5p (a regulator of IL-16 gene) were performed by immunohistochemistry, immunoblotting, and gene expression assays. In addition, we examined changes in nuclear expression of IL-16 expression with regards to exposure to follicle-stimulating hormone (FSH) by in vitro cell culture assays with human ovarian cancer cells. The frequencies of IL-16 expressing cells were significantly higher in ovarian stroma in women at early and late menopause as compared with premenopausal women (P < 0.0001). Similar patterns were also observed for macrophages. Expression of miR-125a-5p decreased significantly (P < 0.001) with the increase in IL-16 expression during aging. Furthermore, expression of nuclear IL-16 increased remarkably upon exposure to FSH. Consequently, ovarian aging is associated with increased expression of IL-16 including its nuclear fraction. Therefore, persistent high levels of FSH in postmenopausal women may be a factor for enhanced expression of IL-16. Effects of increased nuclear fraction of IL-16 need to be examined.

Leukocytes in Critical Patients With Asthma Exacerbation

Background Asthma exacerbations, defined as acute or subacute progressive worsening of airway spasm, are a significant cause of disease morbidity. Risk factors for exacerbation include sex, age, race, socioeconomic status, baseline lung function, smoking history, and exposure to respiratory viruses. It is believed that white cells play an essential role in the pathogenesis of such attacks; however, the current understanding of the relationship between cell lines during an asthma attack is minimal. Methods This report represents a retrospective study for patients admitted to ICU for asthma exacerbations. The Medical Information Mart for Intensive Care iii (MIMIC iii) version 1.4 database was used to identify patients admitted for asthma exacerbations. The demographics, laboratory data gathered in addition, to clinical variables and outcomes were determined. Results The length of stay increased with the increase in WBC (p = 0.001). Intubated patients had an increased white blood cell (WBC) count when compared with non-intubated patients (p-value 0.009). In addition, patients with normal basophil counts on presentation were less likely to need intubation than those presenting with low basophils (p-value 0.015, adjusted odds ratio = 0.074, CI [0.009-0.620]) and those presenting with basophilia (p-value 0.001, adjusted odds ratio = 0.025, CI [0.003-0.225]). Furthermore, prolonged intubation (for three days or more) was positively correlated with eosinophil counts. On the other hand, there was no statistically significant association between the length of ICU and the patient's age, smoking status, or gender (p-values 0.611; 0.761; and 0.201, respectively). Conclusion Asthma exacerbation is a disease of heterogeneous pathophysiology. The leukocyte count is associated with the length of stay and the need for mechanical ventilation.

Fuel feedstock determines biodiesel exhaust toxicity in a human airway epithelial cell exposure model

BACKGROUND

Biodiesel is promoted as a sustainable replacement for commercial diesel. Biodiesel fuel and exhaust properties change depending on the base feedstock oil/fat used during creation. The aims of this study were, for the first time, to compare the exhaust exposure health impacts of a wide range of biodiesels made from different feedstocks and relate these effects with the corresponding exhaust characteristics.

METHOD

Primary airway epithelial cells were exposed to diluted exhaust from an engine running on conventional diesel and biodiesel made from Soy, Canola, Waste Cooking Oil, Tallow, Palm and Cottonseed. Exhaust properties and cellular viability and mediator release were analysed post exposure.

RESULTS

The exhaust physico-chemistry of Tallow biodiesel was the most different to diesel as well as the most toxic, with exposure resulting in significantly decreased cellular viability (95.8 ± 6.5%) and increased release of several immune mediators including IL-6 (+223.11 ± 368.83 pg/mL) and IL-8 (+1516.17 ± 2908.79 pg/mL) above Air controls. In contrast Canola biodiesel was the least toxic with exposure only increasing TNF-α (4.91 ± 8.61).

CONCLUSION

This study, which investigated the toxic effects for the largest range of biodiesels, shows that exposure to different exhausts results in a spectrum of toxic effects in vitro when combusted under identical conditions.

Knockout of MicroRNA-155 Ameliorates the Th17/Th9 Immune Response and Promotes Wound Healing

MiRNAs are integral for maintaining immune homeostasis and self-tolerance. In this study, qPCR analyses were performed to determine which miRNAs play an important role in wound healing. Next, an experiment in a model of wound healing was performed, and histology, mRNA expression and T-cell subpopulations in wound tissue were analyzed. The accelerated experiments were performed by local injection of either rIL-17A and/or rIL-9 after wound healing. In vitro, the differentiation of Th17/Th9 in miR-155^+/+ or miR-155^-/- mice was investigated, and the target genes of miR155 were analyzed. From our findings, miR-155^-/- in mice promoted wound healing and weakened T cell-mediated inflammation, especially in IL-17/IL-9, and less severe skin fibrosis developed in the mice. rIL-17A and/or rIL-9 could exacerbate inflammatory injury and delay wound healing. We also demonstrated that miR-155^-/- led to a defect in the differentiation of Th17/Th9 in vitro, and this effect of IL-17/IL-9 might be related to the expression of C-maf, which is a target gene of miR155. MiR-155 regulated IL-17/IL-9-related inflammation in wound healing and might be a potential therapeutic target to attenuate the inflammatory response in wound tissue and promote the closure of wound injuries.

Physiological Roles of Mast Cells: Collegium Internationale Allergologicum Update 2019

Mast cells are immune cells which have a widespread distribution in nearly all tissues. These cells and their mediators are canonically viewed as primary effector cells in allergic disorders. However, in the last years, mast cells have gained recognition for their involvement in several physiological and pathological conditions. They are highly heterogeneous immune cells displaying a constellation of surface receptors and producing a wide spectrum of inflammatory and immunomodulatory mediators. These features enable the cells to act as sentinels in harmful situations as well as respond to metabolic and immune changes in their microenvironment. Moreover, they communicate with many immune and nonimmune cells implicated in several immunological responses. Although mast cells contribute to host responses in experimental infections, there is no satisfactory model to study how they contribute to infection outcome in humans. Mast cells modulate physiological and pathological angiogenesis and lymphangiogenesis, but their role in tumor initiation and development is still controversial. Cardiac mast cells store and release several mediators that can exert multiple effects in the homeostatic control of different cardiometabolic functions. Although mast cells and their mediators have been simplistically associated with detrimental roles in allergic disorders, there is increasing evidence that they can also have homeostatic or protective roles in several pathophysiological processes. These findings may reflect the functional heterogeneity of different subsets of mast cells.

Interleukin-9 promotes early mast cell-mediated expulsion of Strongyloides ratti but is dispensable for generation of protective memory

IL-9 is a cytokine with pleiotropic function that mediates allergic inflammation and immunity to intestinal helminth parasites. Accumulating evidence suggests that IL-9 acts via both, initiation and regulation of adaptive immune responses and direct activation of intestinal effector pathways. Here we use IL-9 receptor deficient mice on BALB/c and C57BL/6 genetic background to dissect effector and regulatory functions of IL-9 during infection with the parasitic nematode Strongyloides ratti. IL-9 receptor-deficient mice displayed increased intestinal parasite burden and prolonged infection irrespective of the genetic background of the mice. Increased parasite burden was correlated to a reciprocally reduced early degranulation of mucosal mast cells, reduced intestinal IL-13 expression and caused by IL-9 receptor deficiency on hematopoietic cells. We observed additional significant changes in the adaptive immune response to S. ratti infection in the absence of the IL-9 receptor that depended on the mouse strain. However, the generation of protective memory to a second infection was intact in IL-9 receptor-deficient mice, irrespective of the genetic background. In summary, our results support a central role for IL-9 as an early mast cell activating effector cytokine during intestinal helminth infection while non-redundant functions in the initiation and amplification of adaptive immune responses were not apparent.

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 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.

Assessment of the Effects of IL9, IL9R, IL17A, and IL17F Gene Polymorphisms on Women with Allergic Rhinitis in Shahrekord, Iran

Background:

The genes encoding IL9, IL9R, IL17A, and IL17F have recently been implicated in the genetic basis of rhinitis and allergy.

Aim:

The purpose of this study was to assess the association of the single nucleotide polymorphisms (SNPs) of IL9, IL9R, IL17A, and IL17F and potential interaction of these genes with the determination of IgE levels in women with allergic rhinitis (AR) in Shahrekord, Iran.

Subjects and Methods:

In a case–control study, SNPs from the IL9, IL9R, IL17A, and IL17F were genotyped in 394 random samples including 195 AR patients and 199 normal controls. Enzyme-linked immunosorbent assay was performed for the determination of serum total IgE levels. The Student's t-test was used to compare the differences. The Chi-square test was performed to compare proportions of cases with different clinical features among cases with different genotypes. The genotype and allele frequencies were obtained by direct counting. Hardy–Weinberg equilibrium was tested between cases and controls separately. The relative risk associated with rare alleles was estimated as an odds ratio with 95% confidence interval. P ≤ 0.05 was considered statistically significant.

Results:

The rs731476 SNP in the IL9R was significantly associated with the AR phenotype in women. No association was found between any of the other SNPs in IL9, IL17A, and IL17F genes and AR. In the gene–gene interaction analysis, we found that IL9R/IL9 genotype rs731476 T-/rs2069885 G conferred a higher risk for AR phenotype development. We also did not find a significant association in terms of IgE levels between cases and controls.

Conclusion:

Our result suggests that the rs731476 SNP located in the IL9R is associated with an increased susceptibility to AR in females. In a subsequent gene–gene interaction analysis, the rs731476 T-/rs2069885 G-genotype combination (IL9R/IL9) has significantly been associated with the development of the AR phenotype.

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.

Regulation of cellular processes by interleukin-16 in homeostasis and cancer

Interleukin-16 (IL-16) is generated as a precursor molecule that is cleaved by caspase-3 to produce a pro-IL-16 molecule that functions as a regulator of T cell growth, and a secreted peptide that functions as a CD4 and/or CD9 ligand for induction of cell motility and activation. IL-16 has been predominantly studied as a contributing factor in the orchestration of an immune response; however, more recently IL-16 bioactivity has been closely associated with the progression of a number of different cancers. While the association between IL-16 plasma levels and tumor progression has been reported for many types of cancer, the mechanism for IL-16 involvement has been partially elucidated for three of the cancer types, cutaneous T cell lymphoma (CTCL), multiple myeloma (MM), and breast cancer. The mechanism for promoting cell growth is different in each of these cancers and involves a sequence mutation in the pro-molecule facilitating decreased p27(KIP1) levels in CTCL; over expression of the secreted IL-16 molecule to induce proliferation in CTCL T cells, and plasma cells in MM; and increased secreted IL-16 acting to recruit CD4+ pro-tumor macrophages in breast cancer. This article will review the cellular process for generating IL-16, the biological activities for both the pro- and secreted forms of the protein, and then the mechanism by which these forms contribute to cancer progression. As a soluble cytokine the ability to reduce or eliminate IL-16 synthesis through siRNA approaches or bioactivity through the use of neutralizing antibody treatment may represent a novel therapeutic approach.

Multiplex analyses of cytokine and chemokine release from the cultured fibroblast of nasal polyps: the effect of IL-17A

CONCLUSION

Our results demonstrate for the first time a potentially enhanced basal secretion of monocyte chemoattractant protein-1 (MCP-1) and interleukin (IL)-17A-stimulated secretion of IL-6 from nasal polyp fibroblasts, enhanced basal secretion of IL-6 from eosinophilic nasal polyp fibroblasts, and a remarkable up-regulation of IL-9 and granulocyte colony-stimulating factor (G-CSF) from nasal fibroblasts by IL-17A stimulation.

OBJECTIVES

The fibroblast, one of the main cell types making up nasal polyps, is thought to be a target cell of various cytokines.

METHODS

Subcultured fibroblasts were established from human polyp biopsy tissues. Simultaneous quantification of 27 kinds of cytokines and chemokines in culture supernatants in unstimulated and IL-17A-stimulated conditions was performed with a human multiplex cytokine assay system.

RESULTS

The IL-17A receptor was expressed at similar levels in all three groups. In the eosinophilic group, basal secretion levels of IL-6 were significantly higher than those in the control and non-eosinophilic groups. Basal secretion of MCP-1 in both the non-eosinophilic and eosinophilic groups was also higher than that of the control group. Both IL-9 and G-CSF secretion were remarkably enhanced by IL-17A stimulation in all three groups. The receptor-mediated response by IL-17A significantly up-regulated IL-6 release alone in the non-eosinophilic and eosinophilic groups as compared with the control group.

Targeting the EP1 receptor reduces Fas ligand expression and increases the antitumor immune response in an in vivo model of colon cancer

Despite studies demonstrating that inhibition of cyclooxygenase-2 (COX-2)-derived prostaglandin E2 (PGE2 ) has significant chemotherapeutic benefits in vitro and in vivo, inhibition of COX enzymes is associated with serious gastrointestinal and cardiovascular side effects, limiting the clinical utility of these drugs. PGE2 signals through four different receptors (EP1-EP4) and targeting individual receptor(s) may avoid these side effects, while retaining significant anticancer benefits. Here, we show that targeted inhibition of the EP1 receptor in the tumor cells and the tumor microenvironment resulted in the significant inhibition of tumor growth in vivo. Both dietary administration and direct injection of the EP1 receptor-specific antagonist, ONO-8713, effectively reduced the growth of established CT26 tumors in BALB/c mice, with suppression of the EP1 receptor in the tumor cells alone less effective in reducing tumor growth. This antitumor effect was associated with reduced Fas ligand expression and attenuated tumor-induced immune suppression. In particular, tumor infiltration by CD4(+) CD25(+) Foxp3(+) regulatory T cells was decreased, whereas the cytotoxic activity of isolated splenocytes against CT26 cells was increased. F4/80(+) macrophage infiltration was also decreased; however, there was no change in macrophage phenotype. These findings suggest that the EP1 receptor represents a potential target for the treatment of colon cancer.

CD4⁺T cells: differentiation and functions

CD4⁺T cells are crucial in achieving a regulated effective immune response to pathogens. Naive CD4⁺T cells are activated after interaction with antigen-MHC complex and differentiate into specific subtypes depending mainly on the cytokine milieu of the microenvironment. Besides the classical T-helper 1 and T-helper 2, other subsets have been identified, including T-helper 17, regulatory T cell, follicular helper T cell, and T-helper 9, each with a characteristic cytokine profile. For a particular phenotype to be differentiated, a set of cytokine signaling pathways coupled with activation of lineage-specific transcription factors and epigenetic modifications at appropriate genes are required. The effector functions of these cells are mediated by the cytokines secreted by the differentiated cells. This paper will focus on the cytokine-signaling and the network of transcription factors responsible for the differentiation of naive CD4⁺T cells.

IL-16 effects on A549 lung epithelial cells: dependence on CD9 as an IL-16 receptor?

Interleukin-16 (IL-16) is a pro-inflammatory cytokine released by many types of cells found in the lungs, including normal airway and alveolar epithelial cells. Though a chemotactin for CD4(+) cells and eosinophils, IL-16 also modulates their production of factors that influence inflammatory lung diseases, e.g., asthma and allergic rhinitis. To date, little is known about any potential autocrine-like regulatory effects of IL-16. Using a model human alveolar basal epithelial A549 cell line, the present study sought to assess lung epithelial cell responses to IL-16. Potential induced effects on cell growth/function were assessed using MTT reduction, lactate dehydrogenase release, and 5-bromo-2-deoxyuridine incorporation assays. As IL-16 (at locally high levels) can induce CD4(+) cell death via apoptosis, this potential outcome among the A549 cells was also evaluated using TUNEL and changes in expression of caspase-3 and the pro-apoptotic and anti-apoptotic proteins of Bcl-2 family. The data here indicated that IL-16 inhibited A549 cell growth/function and this was associated with a marked increase in apoptosis characterized by DNA fragmentation, activation of caspase-3, and altered pro-apoptotic protein expression. Since lung epithelial cells lack the CD4 that may bind IL-16, it has been suggested that CD9 may act as an alternate receptor for this cytokine (i.e., an IL-16R). Thus, these studies also sought to determine the extent of CD9 expression on A549 cells and if any/all observed IL-16-induced changes were mediated by CD9. Flow cytometric analyses revealed the cells to be CD9(+)CD4(-). However, neutralization of the purported IL-16R with anti-CD9 antibody could not block the cytotoxic/growth inhibiting effects of IL-16. The only exception appeared to be a mitigation of a chemotactic effect of IL-16; however, studies with an equal amount of non-specific antibody (of same isotype as the anti-CD9) revealed this effect to be artefactual. The neutralization study results thus suggest to us that as-yet undefined pathway(s) exist through which IL-16 may act to exert growth inhibiting/apoptosis-inducing effects on A549 cells, a cell line routinely used as a model for lung epithelial cells.

Th9: a new player in asthma pathogenesis?

CD4(+) T helper (Th) cells act as important regulators of the mammalian adaptive immune response. CD4(+) Th cells were originally characterized as either Th1 or Th2 types, based on the cytokines they produce. Over the past two decades, however, we have attained a much more detailed understanding of CD4(+) T-cell differentiation, functions, and gene expression profiles, which led to the identification of additional types, such as the Th17 and induced regulatory T cells. Recently, researchers have characterized yet another novel and distinct population that exists among these immune-modulatory cells. The 'Th9' cells were first identified as a Th2 subpopulation that produced exceptionally large quantities of the Th2-specific cytokine interleukin 9. However, experimental analysis revealed that Th9 cells had divergent regulatory capabilities and were critically involved in different immune processes. In particular, we now know that Th9 acts as a major contributor to the onset and progression of allergies, especially asthma. Here, we will review the heterogeneity and biology of CD4(+) Th cells and summarize the characteristics known to date of interleukin 9 and Th9 cells to build a framework for better understanding of their roles in disease processes, especially in allergy-induced asthma.

The effects of NOS1 gene on asthma and total IgE levels in Taiwanese children, and the interactions with environmental factors

Asthma is a complex disorder, which is known to be affected by interactions between genetic and environmental factors. The aim of this study was to investigate the three microsatellite polymorphisms of GT repeats in intron 2, AAT repeats in intron 20, and CA repeats in exon 29 of the NOS1 gene in 155 asthmatic children and 301 control children, and the interaction with environmental factors in southern Taiwan. Total serum IgE, phadiatop test and genetic polymorphisms were measured. The genotype frequency of 14/14-AAT repeats of the NOS1 gene was significantly higher in the asthmatic group (p = 0.01). Total IgE concentrations were higher in asthmatic children (p = 0.015) carrying the NOS1 14/14-AAT genotype than in subjects with other polymorphisms. The gene and environmental interaction effects were 3.83-fold, 6.86-fold, and 8.04-fold (all corrected p-values <0.001) between subjects carrying at least one NOS1 14-AAT allele and exposure to cockroaches, high levels of total IgE, and positive response against the phadiatop test in asthmatic children. The findings of this study provide strong evidence that NOS1 gene with 14-AAT tandem repeats has a significant effect in asthmatic children. Environmental factors and atopic status will enhance the asthmatic risk for children who carry NOS1 susceptible allele.

Association between IL-1A single nucleotide polymorphisms and chronic beryllium disease and beryllium sensitization

OBJECTIVE

To determine if single nucleotide polymorphisms (SNPs) in interleukin (IL) IL-1A, IL-1B, IL-1RN, IL-2, IL-9, and IL-9R were associated with chronic beryllium disease (CBD) and beryllium sensitization (BeS).

METHODS

Forty SNPs in six IL genes were evaluated in 85 individuals with CBD, 61 individuals with BeS, and 730 individuals without BeS or CBD (nonsensitized) using a 5' nuclease polymerase chain reaction assay. Logistic regression was used to evaluate the association between IL SNPs, CBD, and BeS, adjusting for plant-site and HLA-DPB1Glu69 in additive, dominant, and recessive inheritance models.

RESULTS

IL-1A-1142, IL-1A-3769, and IL-1A-4697 were significantly associated with CBD in both the additive and dominant models compared to individuals with BeS or the nonsensitized.

CONCLUSIONS

These results indicate that genetic variations in the IL-1A gene may play a role in the development of CBD but not BeS.

The other T helper cells in asthma pathogenesis

The complex phenotype of allergic bronchial asthma involves a variable degree of bronchoobstruction, increased mucus production, and airway remodeling. So far it is suggested that it arises from multiple interactions of infiltrating and structural cells in the context of chronic airway inflammation that is orchestrated by T helper 2 (TH2) cells. By secreting a plethora of typical mediators such as interleukin (IL) 4, IL-5, and IL-13, these cells hold a key position in asthma pathogenesis. However, therapeutic approaches targeting these TH2-type mediators failed to improve asthma symptoms and impressively showed that asthma pathogenesis cannot be reduced by TH2 cell functions. Recently, other T helper cells, that is, TH9 and TH17 cells, have been identified and these cells also contribute to asthma pathogenesis, the processes leading to formation or aggravation of asthma. Furthermore, TH25 cells, TH3 cells, and regulatory T cells have also been implicated in asthma pathogenesis. This paper aims at summarizing recent insights about these new T helper cells in asthma pathogenesis.

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).

Sex-specific effect of IL9 polymorphisms on lung function and polysensitization

Sex differences in asthma-associated phenotypes are well known but the genetic factors that may account for these differences have received little attention. This study aimed to characterize sex-specific and pleiotropic genetic factors underlying four quantitative phenotypes involved in the main asthma physiopathological pathways: immunoglobulin E levels, a measure of polysensitization (SPTQ), eosinophil counts and a measure of lung function FEV(1)/H(2) (forced expiratory volume in one second divided by height square). Sex-stratified univariate and bivariate linkage analyses were conducted in 295 families from the Epidemiological study on the Genetics and Environment of Asthma study. We found genome-wide significant evidence for a male-specific pleiotropic QTL (quantitative trait loci) on 5q31 (P=7 x 10(-9)) influencing both FEV(1)/H(2) and SPTQ and for a female-specific pleiotropic QTL on 11q23 underlying SPTQ and immunoglobulin E (P=2 x 10(-5)). Three other sex-specific regions of linkage were detected for eosinophil: 4q24 and 22q13 in females, and 3p25 in males. Further, bivariate association analysis of FEV(1)/H(2) and SPTQ with 5q31 candidate genes in males showed a significant association with two single-nucleotide polymorphisms within IL9 gene, rs2069885 and rs2069882 (P=0.02 and P=0.002, respectively, after Bonferroni's correction). This study underlies the importance of taking into account complex mechanisms, such as heterogeneity according to sex and pleiotropy to unravel the genes involved in asthma phenotypes.

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.

Differentiation potential of a basal epithelial cell line established from human bronchial explant

Due to the cellular complexity of the airway epithelium, it is important to carefully define bronchial cell lines that capture the phenotypic traits of a particular cell type. We describe the characterization of a human bronchial epithelial cell line, VA10. It was established by transfection of primary bronchial epithelial cells with retroviral constructs containing the E6 and E7 oncogenes from HPV16. The cell line has been cultured for over 2 yr, a total of 60 passages. Although prolonged culture resulted in increased chromosomal instability, no major phenotypic drift in marker expression was observed. The cells expressed cytokeratins 5, 13, 14, and 17 suggesting a basal-like phenotype. This was further supported by the expression of alpha6beta4 integrins and the basal cell-associated transcription factor p63. The VA10 cell line generated high transepithelial electrical resistance in suspended and air-liquid interface culture, indicating functionally active tight junction (TJ) complexes. Immunocytochemistry showed the typical reticular structures of occludin and TJ-associated F-actin. VA10 produced pseudostratified layer in air-liquid interface culture with expression of p63 restricted to the basal layer. Furthermore, VA10 produced round colonies when cultured in laminin-rich reconstituted basement membrane, and immunostaining of claudin-1 and the basolateral marker beta4 integrin revealed colonies that generated polarization as expected in vivo. These data indicate that VA10 epithelia have the potential to model the bronchial epithelium in vivo and may be useful to study epithelial regeneration and repair and the effect of chemicals and potential drug candidates on TJ molecules in airway epithelia.

IL-13 mediates in vivo IL-9 activities on lung epithelial cells but not on hematopoietic cells

Increased IL-9 expression, either systemically or under the control of lung-specific promoter, induces an asthma-like phenotype, including mucus overproduction, mastocytosis, lung eosinophilia, and airway hyperresponsiveness. These activities correlate with increased production of other Th2 cytokines such as IL-4, IL-5, and IL-13 in IL-9 Tg mice. To determine the exact role of IL-13 in this phenotype, mice overexpressing IL-9 were crossed with IL-13-deficient mice. In these animals, IL-9 could still induce mastocytosis and B lymphocyte infiltration of the lungs. Although IL-9-induced eosinophilia in the peritoneal cavity was not diminished in the absence of IL-13, IL-13 was required for IL-9 to increase eotaxin expression and lung eosinophilia. Mucus production and up-regulation of lung epithelial genes upon IL-9 overexpression were completely abolished in the absence of IL-13. Using hemopoietic cell transfer experiments with recipients that overexpressed IL-9 but were deficient in the IL-9 receptor (IL-9R), we could demonstrate that the effect of IL-9 on lung epithelial cells is indirect and could be fully restored by transfer of hemopoietic cells expressing IL-9R. Mucus production by lung epithelial cells was only up-regulated when hemopoietic cells simultaneously expressed functional IL-9R and IL-13 genes, indicating that IL-13 is not a cofactor but a direct mediator of the effect of IL-9 on lung epithelial cells. Taken together, these data indicate that IL-9 can promote asthma through IL-13-independent pathways via expansion of mast cells, eosinophils, and B cells, and through induction of IL-13 production by hemopoietic cells for mucus production and recruitment of eosinophils by lung epithelial cells.

Profibrotic effect of IL-9 overexpression in a model of airway remodeling

IL-9 overexpression protects against alveolar fibrosis induced by crystalline silica particles. This cytokine is also involved in allergic asthma. In the present study, we examined the effect of IL-9 overexpression on the subepithelial fibrotic response, a feature of asthmatic remodeling, induced by chronic exposure to Alternaria alternata extract. IL-9-overexpressing mice (Tg5) and their wild-type counterparts (FVB) were intranasally exposed to A. alternata extract or PBS (controls) twice a week during 3 mo. At the end of the allergic challenge, enhanced pause (Penh) measured in response to methacholine and fibrotic parameters, such as collagen and fibronectin lung content, were significantly higher in Tg5 compared with FVB. Staining of lung sections with Masson's Trichrome also showed more collagen fibers in peribronchial areas of treated Tg5 mice. A similar recruitment of inflammatory cells was observed in challenged FVB and Tg5 mice, except for eosinophils, which were significantly more abundant in the lung of Tg5. High serum levels of IgE and IgG1 in both strains indicated that FVB and Tg5 developed a strong type 2 immune response. The concentration of the eosinophil chemoattractant RANTES and the profibrotic mediator connective tissue growth factor (CTGF) was higher in the BAL of challenged Tg5 than FVB. These results demonstrate a profibrotic role of IL-9 in an airway remodeling model, possibly involving eosinophils and CTGF. These data also highlight a dual role of IL-9 in lung fibrosis, being anti- or profibrotic depending on the alveolar or airway localization of the process, respectively.

Up-Regulation of Interleukin-9 and the Interleukin-9-Associated Calcium-Activated Chloride Channel hCLCA1 in Nasal Mucosa Following In Vivo Allergen Challenge

Interleukin (IL)-9 is a pleiotropic T helper 2-type cytokine that has been shown to be up-regulated in allergic airway disease, including asthma. IL-9 has been demonstrated to be a potent stimulus for the production and secretion of mucus from airway epithelial cells via induction of a calcium-activated chloride channel, hCLCA1. The objective of this study was to investigate the expression of IL-9 and hCLCA1 following allergen challenge in the nasal mucosa of allergic rhinitis patients. Nasal biopsies were obtained from allergic rhinitis patients out of allergen season both before (baseline) and after local antigen challenge with either ragweed or diluent (control). Immunohistochemistry and in situ hybridization were used to assess IL-9 protein and hCLCA1 messenger ribonucleic acid. Eosinophils and T cells were detected using immunohistochemistry. IL-9 and hCLCA1 were very low at baseline, and expression was significantly up-regulated following ragweed challenge. Whereas the number of eosinophils increased after allergen challenge, T-cell counts did not change significantly. The results of this study demonstrate the relationship between specific allergen challenge and expression of both IL-9 and hCLCA1, suggesting a possible mechanism for the increased production of mucus from airway epithelial cells in allergic rhinitis.

Der p, IL-4, and TGF-beta cooperatively induce EGFR-dependent TARC expression in airway epithelium

Thymus and Activation-Regulated Chemokine (TARC) may be critical in Th2 cell recruitment in allergic inflammation; however, the mechanisms of allergen-induced TARC release are unclear. Since airway epithelium is the first line of defense to inhaled allergens, we questioned whether house dust mite allergen (Der p) can induce TARC expression in bronchial epithelial cells, how this is regulated at the molecular level, and if micro-environmental cytokines augment this effect. We examined the effects of Der p and the cytokines IL-4 and TGF-beta on TARC expression in 16HBE cells and primary bronchial asthma epithelium. Real-time PCR and immunofluorescence demonstrated that Der p induces TARC expression in bronchial epithelium. Supernatants from Der p-stimulated 16HBE cells were able to induce TARC-dependent T cell trafficking. IL-4 and TGF-beta cooperatively enhanced Der p-induced TARC expression in 16HBE cells. Specific inhibitors, immunodetection, and gel-shifts revealed that these effects are mediated by phosphorylation of the epidermal growth factor receptor (EGFR), mitogen-activated protein kinase (MAPK) signaling and subsequent nuclear factor (NF)-kappaB activation. A Disintegrin And Metalloproteinase (ADAM), a family of proteins involved in shedding of various growth factors, was shown to be responsible for EGFR activation. The increase in TARC production by direct interaction of Der p with the bronchial epithelium may be an important initial step in the generation of allergic inflammation, which is further potentiated by micro-environmental cytokines. Interference with ADAM or EGFR activity may be a novel promising target to prevent TARC release and subsequent allergic inflammation.

Allergen-induced interleukin-9 production in vitro: correlation with atopy in human adults and comparison with interleukin-5 and interleukin-13

BACKGROUND

The contribution of IL-9 to human atopy is supported by genetic studies. However, IL-9 production in response to allergen in vitro has been reported only in children.

OBJECTIVE

Study IL-9 induction by allergen in adults, compare it with IL-5 and IL-13 and evaluate its association with atopy.

METHODS

Peripheral blood mononuclear cell (PBMC) from control adults and from atopic patients were cultured with various allergens or phytohaemagglutinin (PHA) and secreted IL-5, IL-9 and IL-13 were measured by ELISA.

RESULTS

IL-9 was produced in response to Dermatophagoides pteronyssinus (Der p) by PBMC from Der p-hypersensitive adults at levels equivalent to those induced by PHA but with slower kinetics. The induction of IL-9 was allergen specific, reflecting donor RAST profile. In Der p-triggered reactions of non-atopic and atopic subjects, IL-9 showed the highest selectivity for atopics, IL-5 and IL-13 being produced more frequently in non-atopic donors. Significant correlations with specific IgE titres were found for IL-9 with all allergens tested (Der p and two peptides of Bet v 1 birch allergen). For IL-5 and IL-13, they were in the same range for Der p but more variable for birch allergens. Patterns of cytokine production by individual patients in response to allergen reflected these differences: for Der p, IL-5, IL-9 and IL-13 productions were strongly correlated but for birch IL-5 differed from the latter two. The in vitro production of IL-9 reflected clinical hypersensitivity profiles and was higher in individuals with asthma than in those with disease limited to rhinitis and/or conjunctivitis.

CONCLUSIONS

Allergen-triggered IL-9 production in vitro is an excellent marker for atopy in adults given its virtual absence in allergen-stimulated PBMC from non-atopic individuals and its correlation with allergen-specific IgE and asthma.

Intrinsic biochemical and functional differences in bronchial epithelial cells of children with asthma

RATIONALE

Convincing evidence of epithelial damage and aberrant repair exists in adult asthmatic airways, even in the absence of inflammation. However, comparable studies in children have been limited by access and availability of clinical samples.

OBJECTIVES

To determine whether bronchial epithelial cells from children with asthma are inherently distinct from those obtained from children without asthma.

METHODS

Epithelial cells were obtained by nonbronchoscopic bronchial brushing of children with mild asthma (n = 7), atopic children without asthma (n = 9), and healthy children (n = 12). Cells were subject to morphologic, biochemical, molecular, and functional assessment. Responses were also compared with commercially available epithelial cultures and the transformed cell line 16HBE140.

RESULTS

All epithelial cells exhibited a "cobblestone" morphology, which was maintained throughout culture and repeated passage. Expression of cytokeratin 19 varied, with disease phenotype being greatest in healthy nonatopics and lowest in asthmatics. In contrast, expression of cytokeratin 5/14 was greatest in asthmatic samples and least in healthy nonatopic samples. Asthmatic epithelial cells also spontaneously produced significantly greater amounts of interleukin (IL)-6, prostaglandin E2, and epidermal growth factor, and equivalent amounts of IL-1beta and soluble intracellular adhesion molecule-1, but significantly lower amounts of transforming growth factor beta1. This profile was maintained through successive passages. Asthmatic epithelial cells also exhibited greater rates of proliferation than nonasthmatic cells.

CONCLUSIONS

This study has shown that epithelial cells from children with mild asthma are intrinsically different both biochemically and functionally compared with epithelial cells from children without asthma. Importantly, these differences are maintained over successive passages, suggesting that they are not dependent on an in vivo environment.

Carbon black nanoparticles induce type II epithelial cells to release chemotaxins for alveolar macrophages

BACKGROUND

Alveolar macrophages are a key cell in dealing with particles deposited in the lungs and in determining the subsequent response to that particle exposure. Nanoparticles are considered a potential threat to the lungs and the mechanism of pulmonary response to nanoparticles is currently under intense scrutiny. The type II alveolar epithelial cell has previously been shown to release chemoattractants which can recruit alveolar macrophages to sites of particle deposition. The aim of this study was to assess the responses of a type II epithelial cell line (L-2) to both fine and nanoparticle exposure in terms of secretion of chemotactic substances capable of inducing macrophage migration.

RESULTS

Exposure of type II cells to carbon black nanoparticles resulted in significant release of macrophage chemoattractant compared to the negative control and to other dusts tested (fine carbon black and TiO2 and nanoparticle TiO2) as measured by macrophage migration towards type II cell conditioned medium. SDS-PAGE analysis of the conditioned medium from particle treated type II cells revealed that a higher number of protein bands were present in the conditioned medium obtained from type II cells treated with nanoparticle carbon black compared to other dusts tested. Size-fractionation of the chemotaxin-rich supernatant determined that the chemoattractants released from the epithelial cells were between 5 and 30 kDa in size.

CONCLUSION

The highly toxic nature and reactive surface chemistry of the carbon black nanoparticles has very likely induced the type II cell line to release pro-inflammatory mediators that can potentially induce migration of macrophages. This could aid in the rapid recruitment of inflammatory cells to sites of particle deposition and the subsequent removal of the particles by phagocytic cells such as macrophages and neutrophils. Future studies in this area could focus on the exact identity of the substance(s) released by the type II cells in response to particle exposure.

The therapeutic potential in targeting CCR5 and CXCR4 receptors in infectious and allergic pulmonary disease

Targeting chemokines and chemokine receptors in various acute and chronic pulmonary diseases remains a vibrant area of basic and clinical research despite major hurdles including cross-species barriers, toxicity, and redundancy. In this review, we draw upon our basic research with a murine model in which innate and acquired immunity are linked in the development and maintenance of chronic asthma due to Aspergillus fumigatus. Using intact and genetically altered mice, studies have also been undertaken to elucidate safe and effective therapeutic strategies that interrupt the initiation and amplification of inflammatory and immune events that follow the intrapulmonary introduction of Aspergillus into A. fumigatus-sensitized mice. These events include resident immune cell activation, immune and inflammatory cell recruitment to the airways, changes in lung physiology, and profound changes in the architecture of the airway due to the activation of lung resident cells. The expression of 2 major chemokine receptors, namely, CC chemokine receptor (CCR) 5 and CXC chemokine receptor (CXCR) 4, has been identified and their roles in innate and acquired immune events during fungal asthma have been explored. CCR5 and CXCR4 are best known for their roles in human immunodeficiency virus-1 (HIV-1) infection, but both are attractive targets in the context of overt inflammatory and remodeling responses in the lung. This avenue of research is markedly enhanced by the existence of numerous small molecule antagonists that are available to selectively target these receptors.

Immunomodulatory cytokines in asthmatic inflammation

The development of asthmatic inflammation involves a complex array of cytokines that promote the recruitment and activation of a number of different immune cells. While factors involved in initiating and establishing inflammation are well characterized, the process by which this pro-inflammatory cascade is regulated is less well understood. The identification and characterization of immunomodulatory cytokines in asthma has been a difficult proposition. Many of the putative regulatory factors have pleiotropic bioactivities and have been characterized as pro-inflammatory in association with certain pathologic conditions. This chapter addresses the potential role of several endogenous factors which appear to attenuate asthmatic inflammation. Understanding the integration of these factors into the regulation of the inflammatory process will likely result in novel therapeutic approaches.

Involvement of IL-9 in the bronchial phenotype of patients with nasal polyposis

BACKGROUND

Nasal polyposis (NP) is frequently associated with asthma. In this disease, asymptomatic bronchial hyperresponsiveness (BHR) is thought to precede the development of asthma. IL-9 and its receptor have been reported as candidate genes for asthma and to be associated with BHR.

OBJECTIVE

The objective of this study was to assess the contribution of 11-9 to the pathogenesis of BHR in NP by comparing the expression of IL-9 and its receptor in bronchial biopsy specimens from three groups of patients with NP: NP without BHR, NP with asymptomatic BHR, and NP with BHR and asthma.

METHODS

Bronchial biopsy specimens were examined in terms of cellular infiltration and in terms of expression of IL-9 protein and mRNA as well as of its receptor by using immunohistochemistry and in situ hybridization.

RESULTS

Patients with NP with asthma as compared with the two other groups exhibited an increased bronchial infiltration of basophils, eosinophils, and T cells that correlated with the asthma score. The two groups of patients with NP with BHR showed an increased expression in IL-9 protein and mRNA as well as an increase in the expression of IL-9R mRNA at the epithelial level. These modifications were inversely correlated with the airway responsiveness to methacholine, producing a 20% fall in FEV1. There was a close association between IL-9+ cells, IL-5 mRNA expression, and eosinophil infiltration that correlated with each other.

CONCLUSIONS

These results suggest an important role for IL-9 in the pathogenesis of BHR and a causal relation between IL-9 and the development of bronchial eosinophilia in asthma.

Interleukin-9 induces mucous cell metaplasia independent of inflammation

Interleukin-9 (IL-9) has been strongly implicated in the pathogenesis of asthma, including the overproduction of mucus, in humans and in animal models. We evaluated the inflammatory changes associated with the upregulation of mucus production by examining the time course of inflammation after daily intratracheal IL-9 administration to naive C57Bl6 mice for 9 d. IL-9 induced an asthmatic phenotype, which in general took several days to develop, as assessed by the measurement of airway hyperresponsiveness, pulmonary inflammation, and serum immunoglobulin E. However, within 24 h of a single dose of IL-9, muc5ac mRNA upregulation occurred, and increased numbers of periodic acid Schiff/Alcian blue-positive mucous cells appeared. This response occurred before the development of an inflammatory cell influx and was the result of epithelial metaplasia. It seemed that IL-9 evoked mucous cell metaplasia independent of IL-13 because mRNA tissue evaluation indicated that muc5ac upregulation preceded any increase in IL-13 mRNA expression or detectable levels of IL-13 in the brochoalveolar lavage fluid. Therefore, the upregulation of IL-13 by IL-9 may be responsible for the amplification of mucus production but is not required for its initiation. IL-9 seems to directly stimulate mucous cell metaplasia without the requirement of inflammatory cell influx.

Segmental allergen challenge in patients with atopic asthma leads to increased IL-9 expression in bronchoalveolar lavage fluid lymphocytes

BACKGROUND

IL-9 is a T(H)2 cell-derived cytokine that might be involved in the pathophysiology of allergic diseases. Little is known about its expression and release during the allergic response in the human lung.

OBJECTIVE

The expression of IL-9 was measured in 10 atopic subjects with mild asthma and 5 nonatopic healthy control subjects at baseline and 24 hours after segmental sham and allergen challenge.

METHODS

IL-9 protein was measured in bronchoalveolar lavage (BAL) fluid by means of ELISA and detected within the BAL cells by means of immunocytochemistry. Furthermore, IL9 mRNA expression of BAL cells was detected by means of real-time PCR.

RESULTS

Although only low or undetectable amounts of IL9 mRNA and IL-9 protein were present in nonatopic control subjects and atopic asthmatic patients at baseline, there was an increase after segmental allergen challenge in the atopic subjects. Lymphocytes were identified as major cellular sources of IL-9 production by means of immunocytochemistry. Furthermore, IL-9 protein and IL9 mRNA expression correlated with eosinophil numbers in BAL fluid.

CONCLUSIONS

These findings demonstrate that IL-9 is specifically upregulated after local allergen challenge in the lungs of atopic asthmatic patients. Lymphocytes are the major cellular source of IL-9. The increased expression and its correlation with eosinophil numbers suggest a potential role for IL-9 in the late phase of the allergic response.

Tumor necrosis factor-alpha-induced synthesis of interleukin-16 in airway epithelial cells: priming for serotonin stimulation

Epithelial cells from individuals with asthma or from allergen-sensitized mice contain intracellular interleukin (IL)-16 protein, not present in epithelial cells from individuals without asthma or unsensitized mice. IL-16 is only present in the bronchoalveolar lavage (BAL) fluid following airway challenge with either allergen or vasoactive amine. This suggests that the initial response to allergen (sensitization) results in synthesis but not secretion of IL-16. In this study, we investigated what factors produced during the sensitization phase are responsible for epithelial cell priming for IL-16 production. We determined that ovalbumin (OVA)-sensitized mice have an increase in systemic tumor necrosis factor-alpha levels, and that serum or BAL fluid stimulation of bronchial epithelial cells results in production of IL-16 that is subsequently secreted only following serotonin stimulation. The mechanism for IL-16 production was shown to be caspase-3-dependent, and serotonin-induced secretion of IL-16 required binding of the serotonin type 2 receptor. The relevance of the priming effect associated with sensitization for IL-16 production and storage was confirmed in vivo by serotonin airway challenge of OVA-sensitized mice, resulting in rapid secretion of IL-16 into BAL fluid. As IL-16 has been shown to regulate CD4+ cell recruitment and activation, and is detected early following airway challenge of individuals with asthma, this two-step process for IL-16 production by epithelial cells may represent a rapid response mechanism in the orchestration of allergic airway inflammation.

Asthma: future directions

Asthma continues to be a significant health care problem, as reflected by the increasing rise in disease morbidity and mortality. Because steroids are relatively safe, clinically effective, and easy to administer, they remain the gold standard of treatment. After many decades of use, however, it is apparent that inhaled corticosteroids have failed to halt the progression of the asthma epidemic. Newer, more effective drugs are being developed to combat this disease, and the interest in developing new medications to treat allergic disease and asthma has increased exponentially. The financial burden of asthma has also been a significant motivating factor in the development of new medications. It is estimated that in 1998 the total cost of asthma on society was $11 billion [175]. This consideration has further intensified the quest to develop more effective asthma medications. Table 1 reviews the wide array of drugs currently being investigated. With the development and approval of novel asthma treatments, millions of asthma sufferers will undoubtedly have increased therapeutic options for control of their disease in the near future.

A functional polymorphism in the RANTES gene promoter is associated with the development of late-onset asthma

The CC chemokine regulated upon activation, normal T-cell expressed and secreted (RANTES) attracts eosinophils, basophils, and T cells during inflammation and immune response, indicating a possible role for this chemokine in asthma. Both the -403A and -28G alleles of the RANTES promoter region exhibit significantly enhanced promoter activity in reporter constructs in vitro. We therefore investigated the genetic influence of these alleles on the development of asthma using case-control analysis in a Japanese population (298 patients with asthma and 311 control subjects). Given the evidence for heterogeneity of asthma according to age at onset, we divided patients with asthma into three subgroups: 117 late-onset patients with asthma (onset at more than 40 years of age), 83 middle-onset patients with asthma (onset at 20 to 40 years of age), and 98 early-onset patients with asthma (onset at less than 20 years of age). The -28G allele was significantly associated with late-onset asthma (odds ratio = 2.033; 95% confidence interval, 1.379-2.998; corrected p < 0.0025) but was not associated with the other two asthma subgroups. The -403A allele was not associated with any of the asthma subgroups. Further evidence of the importance of the -28G allele was a significant increase in the production of RANTES in vitro in individuals who carried this allele. Our findings suggest that, among Japanese, the -28G allele of the RANTES promoter region confers susceptibility to late-onset asthma.

Elevated expression of interleukin-9 mRNA in the bronchial mucosa of atopic asthmatics and allergen-induced cutaneous late-phase reaction: relationships to eosinophils, mast cells and T lymphocytes

BACKGROUND

Interleukin-9 is a T cell-derived Th2-type cytokine that has been linked to airway hyper-responsiveness, mucus hypersecretion and mast cell infiltration in animal models. We recently demonstrated the potential for IL-9 to act in human eosinophil development and survival.

OBJECTIVES

The aims of this study were: (i) to compare IL-9 mRNA expression in bronchial biopsies between atopic asthmatics and normal controls, (ii) to investigate kinetic expression of IL-9 mRNA in skin biopsies after allergen challenge; and (iii) to relate IL-9 expression to infiltration of eosinophils, mast cell and T lymphocytes in local tissue.

METHODS

Bronchial biopsies were obtained from atopic asthmatics (n = 12) and normal non-asthmatics (n = 12) at baseline. Skin biopsies were obtained from atopic subjects (n = 11) at 1, 3, 6, 24, 48 and 72 h after allergen challenge. Diluent challenge sites at 24 h were used as controls. IL-9 mRNA was identified using the technique of in situ hybridization. The numbers of eosinophils, mast cells and T cells were evaluated by immunohistochemistry.

RESULTS

The numbers of IL-9 mRNA(+) cells present in the bronchial mucosa were significantly greater in atopic asthmatics than those in normal controls (P = 0.003). The numbers of eosinophils, but not mast cells, were also significantly higher in asthmatics (P < 0.005). The numbers of IL-9 mRNA(+) cells present in the airway of asthmatics significantly correlated with the numbers of eosinophils (r = 0.623, P = 0.03), but not mast cells or T cells. Compared with diluent challenge, the numbers of IL-9 mRNA(+) cells were significantly elevated at all allergen-challenged sites in the skin, with maximal signals at 48 h (P < 0.005). At 72 h, the numbers of IL-9 mRNA(+) cells significantly correlated with the numbers of eosinophils (r = 0.707, P = 0.015).

CONCLUSION

Elevated expression of IL-9 in allergic inflammation may contribute to local eosinophil infiltration and survival in asthma and other allergic atopic diseases.