MAP kinase inhibitor PD98059 regulates Th1, Th9, Th17, and natural T regulatory cells in an experimental autoimmune encephalomyelitis mouse model of multiple sclerosis

Experimental autoimmune encephalitis (EAE), an animal model of multiple sclerosis (MS), provides significant insights into the mechanisms that initiate and drive autoimmunity. MS is a chronic autoimmune disease of the central nervous system, characterized by inflammatory infiltration associated with demyelination. T lymphocyte cells play a crucial role in MS, whereas natural T regulatory (nTreg) cells prevent autoimmune inflammation by suppressing lymphocyte activity. This study sought to investigate the role of PD98059, a selective MAP kinase inhibitor, in Th1, Th9, Th17, and nTreg cells using the SJL/J mouse model of EAE. Following EAE development, the mice were intraperitoneally administered PD98059 (5 mg/kg for two weeks) daily. We evaluated the effects of PD98059 on Th1 (IFN-γ and T-bet), Th9 (IL-9 and IRF4), Th17 (IL-17A and RORγT), and nTreg (FoxP3 and Helios) cells in the spleen using flow cytometry. Moreover, we explored the effects of PD98059 on the IFN-γ, T-bet, IL-9, IRF4, IL-17A, RORγT, FoxP3, and Helios mRNA and protein levels in brain tissues using qRT-PCR and Western blot analyses. PD98059 treatment significantly decreased the proportion of CD4+IFN-γ+, CD4+T-bet+, CD4+IL-9+, CD4+IRF4+, CD4+IL-17A+, CD4+RORγT+, CD4+IL-17A+, and CD4+RORγT+ cells while increasing that of CD4+FoxP3+ and CD4+Helios+ cells. In addition, PD98059 administration decreased the mRNA and protein levels of IFN-γ, T-bet, IL-9, IRF4, IL-17A, and RORγT but increased those of FoxP3 and Helios in the brain tissue of EAE mice. Our findings suggest that PD98059 corrects immune dysfunction in EAE mice, which is concurrent with the modulation of multiple signaling pathways.

The Exposure to Lead (Pb) Exacerbates Immunological Abnormalities in BTBR T+ Itpr3tf/J Mice through the Regulation of Signaling Pathways Relevant to T Cells

Autism spectrum disorder (ASD) is a common neurodevelopmental illness characterized by abnormal social interactions, communication difficulties, and repetitive and limited behaviors or interests. The BTBR T+ Itpr3tf/J (BTBR) mice have been used extensively to research the ASD-like phenotype. Lead (Pb) is a hazardous chemical linked to organ damage in the human body. It is regarded as one of the most common metal exposure sources and has been connected to the development of neurological abnormalities. We used flow cytometry to investigate the molecular mechanism behind the effect of Pb exposure on subsets of CD4+ T cells in the spleen expressing IFN-γ, T-bet, STAT1, STAT4, IL-9, IRF4, IL-22, AhR, IL-10, and Foxp3. Furthermore, using RT-PCR, we studied the effect of Pb on the expression of numerous genes in brain tissue, including IFN-γ, T-bet, STAT1, STAT4, IL-9, IRF4, IL-22, AhR, IL-10, and Foxp3. Pb exposure increased the population of CD4+IFN-γ+, CD4+T-bet+, CD4+STAT1+, CD4+STAT4+, CD4+IL-9+, CD4+IRF4+, CD4+IL-22+, and CD4+AhR+ cells in BTBR mice. In contrast, CD4+IL-10+ and CD4+Foxp3+ cells were downregulated in the spleen cells of Pb-exposed BTBR mice compared to those treated with vehicle. Furthermore, Pb exposure led to a significant increase in IFN-γ, T-bet, STAT1, STAT4, IL-9, IRF4, IL-22, and AhR mRNA expression in BTBR mice. In contrast, IL-10 and Foxp3 mRNA expression was significantly lower in those treated with the vehicle. Our data suggest that Pb exposure exacerbates immunological dysfunctions associated with ASD. These data imply that Pb exposure may increase the risk of ASD.

Establishment and Characterization of a Murine Mucosal Mast Cell Culture Model

Accumulating evidence suggests that mast cells play critical roles in disruption and maintenance of intestinal homeostasis, although it remains unknown how they affect the local microenvironment. Interleukin-9 (IL-9) was found to play critical roles in intestinal mast cell accumulation induced in various pathological conditions, such as parasite infection and oral allergen-induced anaphylaxis. Newly recruited intestinal mast cells trigger inflammatory responses and damage epithelial integrity through release of a wide variety of mediators including mast cell proteases. We established a novel culture model (IL-9-modified mast cells, MCs/IL-9), in which murine IL-3-dependent bone-marrow-derived cultured mast cells (BMMCs) were further cultured in the presence of stem cell factor and IL-9. In MCs/IL-9, drastic upregulation of Mcpt1 and Mcpt2 was found. Although histamine storage and tryptase activity were significantly downregulated in the presence of SCF and IL-9, this was entirely reversed when mast cells were cocultured with a murine fibroblastic cell line, Swiss 3T3. MCs/IL-9 underwent degranulation upon IgE-mediated antigen stimulation, which was found to less sensitive to lower concentrations of IgE in comparison with BMMCs. This model might be useful for investigation of the spatiotemporal changes of newly recruited intestinal mast cells.

Targeted blockade of interleukin 9 inhibits tumor growth in murine model of pancreatic cancer

BACKGROUND

Interleukin 9 (IL-9) has been implicated in the pathogenesis of several tumor types, but the role of anti-IL-9 in pancreatic cancer remains unclear.

OBJECTIVES

We aimed to explore the mechanism and effects of blockading IL-9 in a pancreatic cancer mouse model.

MATERIAL AND METHODS

Panc02 cells were injected subcutaneously into mice to establish a mouse model. The mice were randomly categorized into 3 groups - the control group, the immunoglobulin G (IgG) group and the anti-IL-9 group - corresponding to intravenous tail injection of phosphate-buffered saline (PBS), IgG isotype antibody and anti-IL-9 antibody, respectively. Then, the expression of IL-9, interleukin-9 receptor (IL-9r), Janus kinase 1 (Jak1), Jak3, and signal transducer and activator of transcription 3 (Stat3) mRNA was tested with quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Interleukin 9 in the tumor tissue was detected using enzyme-linked immunosorbent assay (ELISA). Western blotting and immunocytochemistry were performed to detect STAT3 and phosphorylation signal transducers and activators of transcription-3 (pSTAT3). Matrix metalloproteinase 2 (MMP2), MMP9 and vascular endothelial growth factor (VEGF) levels were assessed using immunocytochemistry.

RESULTS

Tumor weight in the anti-IL-9 group was significantly lower than in the other groups (p < 0.05). There was a remarkable survival benefit in the anti-IL-9 group compared to the other groups (p < 0.05). The concentration of IL-9 in tumor tissue was significantly downregulated in the anti-IL-9-treated mice (p < 0.05). The expression of Jak1 and Jak3 mRNA and pSTAT3, MMP2 and MMP9 proteins in the anti-IL-9 group was lower than that of the PBS or IgG groups (p < 0.05), but the STAT3 and VEGF protein levels showed no significant difference (p < 0.05).

CONCLUSIONS

Anti-IL-9 antibody could effectively restrain the growth of pancreatic cancer in mice, and this effect may partly occur by blocking the STAT3 pathway.

Analysis of Long Noncoding RNA and mRNA Expression Profiles in IL-9-Activated Astrocytes and EAE Mice

BACKGROUND/AIMS

Multiple sclerosis (MS) is an autoimmune disease in the central nervous system associated with demyelination and axonal injury. Astrocyte activation is involved in the pathogenesis of MS and experimental autoimmune encephalomyelitis (EAE), an animal model of MS. This study was designed to find potential lncRNAs in EAE mice and activated astrocytes.

METHODS

we performed microarray analysis of lncRNAs from the brain tissues of EAE mice and primary mouse astrocytes treated with IL-9(50 ng/ml). 12 lncRNAs were validated through real-time PCR. Gene ontology and KEGG pathway analysis were applied to explore the potential functions of lncRNAs.

RESULTS

Differentially expressed 3300 lncRNAs and 3250 mRNAs were in the brain tissues of EAE mice, and 3748 lncRNAs and 3332 mRNAs were in activated astrocytes. Notably, there were 2 co-up-regulated lncRNAs and 3 co-down-regulated lncRNAs both in the brain tissues of EAE mice and in activated astrocytes, including Gm14005, Gm12478, mouselincRNA1117, AK080435, and mouselincRNA0681, which regulate the ER calcium flux kinetics, zinc finger protein and cell apoptosis. Similarly, there were 7 mRNAs co-up-regulated and 2 mRNAs co-down-regulated both in vivo and in vitro. Gene ontology and KEGG pathway analysis showed that the biological functions of differentially expressed mRNAs were associated with metabolism, development and inflammation. The results of realtime PCR validation were consistent with the data from the microarrays.

CONCLUSIONS

Our data uncovered the expression profiles of lncRNAs and mRNAs in vivo and in vitro, which may help delineate the mechanisms of astrocyte activation during MS/EAE process.

[Interleukin-9 promotes pancreatic cancer cell proliferation and migration via activation of STAT3 pathway]

Objective To investigate the impact of interleukin-9 (IL-9) on proliferation, invasion and migration of pancreatic cancer cells and its mechanism. Methods PANC-1 cells were cultured in vitro and treated with IL-9 at different concentrations (5, 10, 20 ng/mL) for 24 hours. The level of IL-9R mRNA was analyzed by quantitative real-time PCR. CCK-8 assay was used to test the proliferation of the cells and flow cytometry to detect the cell apoptosis. Transwell^TM assay was employed to determine the invasion and migration of PANC-1 cells. Western blotting was used to detect the STAT3 and p-STAT3 protein expression levels. After PANC-1 cells were treated with different concentrations of STAT3 pathway inhibitor AG490, followed by IL-9 treatment, the STAT3 and p-STAT3 protein expressions, as well as the proliferation of the cells were detected again. Results The level of IL-9R mRNA and the proliferation rate of PANC-1 cells were enhanced with the increase of IL-9 concentration, and the capacities of cell invasion and migration were promoted significantly. The relative protein expression of p-STAT3 increased greatly in PANC-1 cells after the treatment of IL-9, but STAT3 were not changed significantly compared with the ones without IL-9 treatment. The proliferation-promoting effect of IL-9 on AG490-pretreated PANC-1 cells was induced, and the p-STAT3 protein expression level was notably inhibited. Conclusion The activation of STAT3 pathway is strongly associated with the process that IL-9 mediates the promotion of proliferation, invasion and migration in pancreatic cancer cells.

Chronic IL9 and IL-13 exposure leads to an altered differentiation of ciliated cells in a well-differentiated paediatric bronchial epithelial cell model

Asthma is a chronic inflammatory disease characterised by airways remodelling. In mouse models IL-9 and IL-13 have been implicated in airways remodelling including mucus hypersecretion and goblet cell hyperplasia. Their role, especially that of IL-9, has been much less studied in authentic human ex vivo models of the bronchial epithelium from normal and asthmatic children. We assessed the effects of IL-9, IL-13 and an IL-9/IL-13 combination, during differentiation of bronchial epithelial cells from normal (n = 6) and asthmatic (n = 8) children. Cultures were analysed for morphological markers and factors associated with altered differentiation (MUC5AC, SPDEF and MMP-7). IL-9, IL-9/IL-13 combination and IL-13 stimulated bronchial epithelial cells from normal children had fewer ciliated cells [14.8% (SD 8.9), p = 0.048, 12.4 (SD 6.1), p = 0.016 and 7.3% (SD 6.6), p = 0.031] respectively compared with unstimulated [(21.4% (SD 9.6)]. IL-9 stimulation had no effect on goblet cell number in either group whereas IL-9/IL-13 combination and IL-13 significantly increased goblet cell number [24.8% (SD 8.8), p = 0.02), 32.9% (SD 8.6), p = 0.007] compared with unstimulated normal bronchial cells [(18.6% (SD 6.2)]. All stimulations increased MUC5AC mRNA in bronchial epithelial cells from normal children and increased MUC5AC mucin secretion. MMP-7 localisation was dysregulated in normal bronchial epithelium stimulated with Th2 cytokines which resembled the unstimulated bronchial epithelium of asthmatic children. All stimulations resulted in a significant reduction in transepithelial electrical resistance values over time suggesting a role in altered tight junction formation. We conclude that IL-9 does not increase goblet cell numbers in bronchial epithelial cell cultures from normal or asthmatic children. IL-9 and IL-13 alone and in combination, reduce ciliated cell numbers and transepithelial electrical resistance during differentiation of normal epithelium, which clinically could inhibit mucociliary clearance and drive an altered repair mechanism. This suggests an alternative role for IL-9 in airways remodelling and reaffirms IL-9 as a potential therapeutic target.

IL-9 induces VEGF secretion from human mast cells and IL-9/IL-9 receptor genes are overexpressed in atopic dermatitis

Interleukin 9 (IL-9) has been implicated in mast cell-related inflammatory diseases, such as asthma, where vascular endothelial growth factor (VEGF) is involved. Here we report that IL-9 (10–20 ng/ml) induces gene expression and secretion of VEGF from human LAD2. IL-9 does not induce mast cell degranulation or the release of other mediators (IL-1, IL-8, or TNF). VEGF production in response to IL-9 involves STAT-3 activation. The effect is inhibited (about 80%) by the STAT-3 inhibitor, Stattic. Gene-expression of IL-9 and IL-9 receptor is significantly increased in lesional skin areas of atopic dermatitis (AD) patients as compared to normal control skin, while serum IL-9 is not different from controls. These results imply that functional interactions between IL-9 and mast cells leading to VEGF release contribute to the initiation/propagation of the pathogenesis of AD, a skin inflammatory disease.

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.

New activation modus of STAT3: a tyrosine-less region of the interleukin-22 receptor recruits STAT3 by interacting with its coiled-coil domain

Activation of STAT proteins by cytokines is initiated by their Src homology 2 domain-mediated association with phosphotyrosine residues from the cytoplasmic domain of a receptor. Here, we show that the C terminus of the interleukin-22 receptor (IL-22R) recruits in a tyrosine-independent manner the coiled-coil domain of STAT3. Mutation of all IL-22R cytoplasmic tyrosines did not abolish activation of STAT3, in contrast to that of STAT1 and STAT5. Coimmunoprecipitation and glutathione S-transferase pulldown experiments showed that the coiled-coil domain of STAT3 is constitutively associated with the C-terminal part of IL-22R, and a chimeric STAT3-STAT5 protein containing the coiled-coil domain of STAT3 could be activated by this tyrosine-independent mechanism. Deletion of the C-terminal part of IL-22R dramatically decreased its ability to activate STAT3 and to mediate IL-22 activity in cell lines, demonstrating that preassociation of STAT3 with this cytokine receptor, independent from the interaction between the Src homology 2 domain and phosphotyrosines, is required for its full activity.

IL-9 induces differentiation of TH17 cells and enhances function of FoxP3+ natural regulatory T cells

The development of T helper (T(H))17 and regulatory T (T(reg)) cells is reciprocally regulated by cytokines. Transforming growth factor (TGF)-beta alone induces FoxP3(+) T(reg) cells, but together with IL-6 or IL-21 induces T(H)17 cells. Here we demonstrate that IL-9 is a key molecule that affects differentiation of T(H)17 cells and T(reg) function. IL-9 predominantly produced by T(H)17 cells, synergizes with TGF-beta1 to differentiate naïve CD4(+) T cells into T(H)17 cells, while IL-9 secretion by T(H)17 cells is regulated by IL-23. Interestingly, IL-9 enhances the suppressive functions of FoxP3(+) CD4(+) T(reg) cells in vitro, and absence of IL-9 signaling weakens the suppressive activity of nT(regs) in vivo, leading to an increase in effector cells and worsening of experimental autoimmune encephalomyelitis. The mechanism of IL-9 effects on T(H)17 and T(regs) is through activation of STAT3 and STAT5 signaling. Our findings highlight a role of IL-9 as a regulator of pathogenic versus protective mechanisms of immune responses.

Expression of IL-9 receptor alpha chain on human germinal center B cells modulates IgE secretion

BACKGROUND

IL-9 has been shown to affect the differentiation pathway of different cell types. However, its potential role in the maturation pathway of antigen-driven B-cell differentiation and its functional effects remain unknown.

OBJECTIVE

To characterize IL-9 receptor alpha chain (IL-9R alpha) expression on human tonsillar B cells at different maturational stages, and to assess its effect on IgE production.

METHODS

Freshly purified human tonsillar B cells were fractionated into 3 populations: low-density (LD), medium-density, and high-density cells. Expression levels of IL-9R alpha were determined by using immunohistochemistry and flow cytometry. IL-9R alpha(high)-expressing cells were stimulated with IL-9 in the presence or absence of IL-4, and IgE release was measured by ELISA.

RESULTS

IL-9R alpha was expressed on human LD tonsillar B cells, with an ability to transduce signals through activation of signal transducer and activator of transcription 3 and 5. Although IL-9 was unable to induce IgE secretion by itself, it potentiated IL-4-mediated IgE production from LD cells. Moreover, increased IgE was paralleled by an upregulation of IL-9R alpha and CD27, with the latter a memory B-cell marker implicated in increased IgE secretion.

CONCLUSION

These results highlight a crucial role for IL-9 in modulating T-cell-dependent B-cell differentiation and establish a new paradigm for understanding the synergistic role of T(H)2 cytokines and their modulatory effect on B-cell maturation and IgE production.

CLINICAL IMPLICATIONS

IL-9 appears to be involved in memory B-cell differentiation and T(H)2-mediated allergic diseases such as asthma.

IL-9 and IL-13 induce mucous cell metaplasia that is reduced by IFN-gamma in a Bax-mediated pathway

One of the major aspects of airway remodeling in asthma is the development of mucous cell metaplasia (MCM). The role of cytokines in the generation and resolution of MCM has been studied in mice and in isolated airway epithelial cells in culture. However, studies using organ cultures that keep the tubular structure of the airways intact and allow studies in the absence of inflammatory cells have not been reported. We established an organ culture system that replicates the allergen-induced MCM in mice and analyzed the role of Bax in the IFN-gamma-induced resolution of MCM. IL-9 or IL-13 induced MCM independently, but a combined IL-9/IL-13 treatment enhanced MCM synergistically. Addition of IFN-gamma at 0.1 ng/ml concentration further increased MCM to levels observed in allergen-exposed mice in vivo. However, MCM was reduced when explants were treated with 50 ng/ml IFN-gamma after MCM was established. While IL-9/IL-13 induced MCM in bronchioles microdissected from bax(+/+) and bax(-/-) mice to a similar extent, IFN-gamma treatment reduced MCM only in bronchioles from bax(+/+) but not in bax(-/-) bronchioles. Restoration of Bax expression in bax(-/-) bronchioles using an adenoviral expression system reduced IL-9/IL-13-induced MCM while MCM was similar in noninfected or adenoviral green fluorescent protein-infected bax(-/-) bronchioles. Furthermore, expressing Bax using an adenoviral expression system reduced allergen-induced MCM in mice. These studies show that allergen-induced MCM is a response to a combination of various cytokines at defined concentrations and that IFN-gamma requires Bax for the resolution of MCM.

JAK kinases overexpression promotes in vitro cell transformation

Constitutive activation of the JAK-STAT pathway is frequent in cancer and contributes to oncogenesis. Here, we took advantage of the Ba/F3 cell line, a murine proB cell line dependent on IL-3 for growth, to analyse mechanisms of constitutive STAT activation in vitro. Cytokine-independent and tumorigenic Ba/F3 cell lines were derived from a two-step selection process. Cells transfected with a defective IL-9 receptor acquire IL-9 responsiveness during a first step of selection, and progress after a second selection step to autonomously growing tumorigenic cells. Microarray analysis pointed to JAK1 overexpression as a key genetic event in this transformation. Overexpression of JAK1 not only increased the sensitivity to IL-9 but also allowed a second selection step toward cytokine-independent growth with constitutive STAT activation. This progression was dependent on a functional FERM and kinase JAK1 domain. Similar results were observed after JAK2, JAK3 and TYK2 overexpression. All autonomous cell lines showed an activation of STAT5, ERK1-2 and AKT but only TYK2-overexpressing cell lines showed a constitutive activation of STAT3. Thus, JAK overexpression can be considered as one of the oncogenic events leading to the constitutive activation of the JAK-STAT pathway.

IL-9 promotes anti-Mycobacterium leprae cytotoxicity: involvement of IFNgamma

Interleukin 9 (IL-9) is a T-cell derived factor preferentially expressed by CD4+ Th2 cells and it has been characterized both in human and murine systems. It is a pleiotropic cytokine with multiple functions on cells of the lymphoid, myeloid and mast cell lineages, as well as on lung epithelial cells. Other activities described for IL-9 support its contribution to asthma and its important role in helminthic infections, where a Th2 response can be protective and IL-9 enhances resistance or is responsible for elimination of the nematode. Nevertheless, until recently there were no studies on its role in bacterial infections in man. We have demonstrated that cytokines can modulate the specific cytotoxicity generation in peripheral blood mononuclear cells from leprosy patients and normal controls. In the present report we studied the effect of IL-9 in this experimental model. Our results indicate that IL-9 can counteract the negative effect mediated by IL-4 on the generation of M. leprae-induced cytotoxic T lymphocytes. Moreover, it can increase this lytic activity in controls and enhance the stimulatory effect of IL-2 or IL-6 in cells from leprosy patients and controls. IL-9 is also able to revert the inhibitory effect of IL-10 and IL-13 on the M. leprae-induced cytotoxic activity. Although the exact mechanism of action of IL-9 remains to be determined, interferon gamma seems to be required for the effect of IL-9 in this experimental model. These data suggest that IL-9 may have an atypical Th2 behaviour and play a role in the modulation of the immune response to mycobacterial infections.

IL-9 modulated MUC4 gene and glycoprotein expression in airway epithelial cells

Compromised epithelial cell integrity is a common feature associated with chronic lung inflammatory states such as asthma. While epithelial cell damage is largely due to sustained effects of inflammatory mediators localized to airways, the subsequent process of epithelial cell differentiation is attributed to members of the transmembrane receptor tyrosine kinase family called the ErbB's. MUC4, a large molecular weight membrane-bound glycoprotein, has recently been identified as a potential ligand for the ErbB-2 receptor. In this study, we investigated the possible role of interleukin-9 (IL-9), a Th2 cytokine, on MUC4 expression using a lung cancer cell line, NCI-H650. We determined that IL-9 up-regulates MUC4 expression in a time and concentration-dependent fashion. Nuclear run-on assays indicated transcriptional regulation of MUC4 while no post-transcriptional mRNA stabilization was observed by actinomycin D chase experiments. IL-9 also increased MUC4 glycoprotein expression as determined by Western blots using a monoclonal antibody specific for a non-tandem repeat region on ASGP-2 region of MUC4. Furthermore, a JAK3-selective inhibitor 4-(4'-hydroxyphenyl) amino-6, 7-dimethoxyquinazoline (WHI-P131), substantially reduced IL-9-induced MUC4 mRNA expression in a dose-dependent fashion. These results implicate a potential role for IL-9 upon MUC4 expression in human airway epithelial cells.

Interleukin-9 stimulates the production of interleukin-5 in CD4+ T cells

We recently showed that interleukin-9 (IL-9), a Th2 cytokine, promotes IL-5-mediated rejection of allografts in mice. This observation led us to investigate the functional link between IL-9 and IL-5 production during alloreactive T cell responses in vitro and in vivo. Firstly, we found that IL-9 was produced by alloreactive Th2 cells, and IL-9 mRNA was detected in skin allograft during Th2-type rejection. We then established that IL-5 production was impaired in alloreactive Th2 cells isolated from IL-9-deficient mice and that optimal IL-5 production after allogeneic stimulation requires a functional IL-9 receptor (IL-9R) on the responding cells. Finally, the production of IL-5 by anti-CD3-stimulated CD4+ T cells was abolished by neutralization of IL-9. Despite the fact that IL-9 promotes IL-5 production by alloreactive T cells, IL-9-deficient recipients of skin allografts still developed eosinophilic graft infiltrates and neither IL-9 nor IL-9R deficiency modified Th2-type allograft rejection.

Decreased expression of uteroglobin-related protein 1 in inflamed mouse airways is mediated by IL-9

Uteroglobin-related protein 1 (UGRP1) is a secretory protein, highly expressed in epithelial cells of airways. Although an involvement of UGRP1 in the pathogenesis of asthma has been suggested, its function in airways remains unclear. In the present study, a relationship between airway inflammation, UGRP1 expression, and interleukin-9 (IL-9), an asthma candidate gene, was evaluated by using a murine model of allergic bronchial asthma. A severe airway inflammation accompanied by airway eosinophilia and elevation of IL-9 in bronchoalveolar lavage (BAL) fluids was observed after ovalbumin (OVA) challenge to OVA-sensitized mice. In this animal model of airway inflammation, lung Ugrp1 mRNA expression was greatly decreased compared with control mice. A significant inverse correlation between lung Ugrp1 mRNA levels and IL-9 levels in BAL fluid was demonstrated by regression analysis (r = 0.616, P = 0.023). Immunohistochemical analysis revealed a distinct localization of UGRP1 in airway epithelial cells of control mice, whereas UGRP1 staining was patchy and faint in inflamed airways. Intranasal administration of IL-9 to naive mice decreased the level of Ugrp1 expression in lungs. These findings suggest that UGRP1 is downregulated in inflamed airways, such as allergic asthmatics, and IL-9 might be an important mediator for modulating UGRP1 expression.

Common gamma chain-signaling cytokines promote proliferation of T-cell acute lymphoblastic leukemia

BACKGROUND AND OBJECTIVES

The identification of signals critical for the pathophysiology of T-cell acute lymphoblastic leukemia (T-ALL) should contribute to the development of novel, more effective therapeutic strategies. Common gamma-chain signaling cytokines (gammac-cytokines) - interleukins 2, 4, 7, 9 and 15 - differentially regulate T-cell development, survival, proliferation and differentiation. Although studies exist on some individual cytokines, no comprehensive analysis of the effects of the Zc-cytokine family on malignant T cells has been reported. Here, we examined the effect of Zc-cytokines on T-ALL proliferation.

DESIGN AND METHODS

Primary leukemic cells were collected at diagnosis from the blood or bone marrow of children with T-ALL. The cells were immunophenotyped and classified according to maturation stage. Proliferative responses to gammac-cytokines were assessed by 3H-thymidine incorporation.

RESULTS

All gammac-cytokines promoted proliferation of primary T-ALL cells. Interleukin (IL)-7 was the cytokine that most frequently induced leukemic cell proliferation and promoted the most robust responses. IL-4 preferentially stimulated proliferation of samples with a more mature immunophenotype, whereas CD1a-positive cortical T-ALL cells were less responsive to IL-9. Finally, combinations of two Zc-cytokines showed synergistic or additive proliferative effects.

INTERPRETATION AND CONCLUSIONS

This study indicates that all the gammac-cytokines tested can stimulate proliferation of leukemic T cells and suggests that synergistic effects may occur in vivo. We present the first demonstration that IL-9 and IL-15 can provide a proliferative signal to T-ALL cells. Importantly, our results support the hypothesis that IL-7 may function as a critical regulator of T-ALL and that its activity may be potentiated by other Zc-cytokines.

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

Recent work has shown the potential importance of IL-9 in allergic diseases. The development of transgenic mice overexpressing IL-9 has suggested a key role for this cytokine in the development of the asthmatic phenotype including airway eosinophilia. In this study, we evaluated the expression of the IL-9R and the effects of IL-9 on human ASM cells by examining the release of Th2-associated chemokines (eotaxin1/CCL11 and thymus- and activation-regulated chemokine (TARC)/CCL17). IL-9R alpha-chain mRNA and surface expression were detected in cultured human airway smooth muscle (ASM) cells. In addition, primary cultured ASM cells, as well as bronchial smooth muscle cells within biopsies of asthmatics and not control subjects, revealed IL-9R protein expression. IL-9 stimulation of human ASM cells resulted in release of eotaxin1/CCL11, but had no effect on the release of TARC/CCL17, in time- and dose-dependent manner. Moreover, in vitro chemotaxis assay demonstrated that conditioned medium from IL-9-stimulated ASM cells attracted human eosinophils. Neutralizing Abs to IL-9, but not to IL-4 or IL-13, reduced significantly IL-9-induced production of eotaxin1/CCL11 from ASM cells. Interestingly, real-time RT-PCR showed that IL-9 up-regulated eotaxin1/CCL11 mRNA expression, but had no effect on TARC/CCL17. Treatment with Act D abrogates IL-9-induced eotaxin1/CCL11 mRNA and protein release by ASM cells. Finally, transfection study using eotaxin1/CCL11 promoter luciferase construct confirmed that IL-9 induced eotaxin1/CCL11 at the transcriptional level. Taken together, these data provide new evidence demonstrating that IL-9-dependent activation of ASM cells contributes to eosinophilic inflammation observed 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.

Interleukin-9 influences chemokine release in airway smooth muscle: role of ERK

Interleukin (IL)-9 is a pleiotropic cytokine that has been proposed as a candidate gene for asthma. As IL-9 expression is correlated with airway hyperresponsiveness in animals, we examined the effects of IL-9 on cultured human airway smooth muscle (HASM) cells. IL-9 alone had no effect on IL-8 release, but at concentrations of > or =30 ng/ml, IL-9 significantly increased IL-8 release induced by TNF-alpha. IL-9 increased phosphorylation of extracellular signal-regulated protein kinase (ERK, p42 and p44) in a concentration- and time-dependent fashion, and U-0126 (10 micro M), which inhibits ERK phosphorylation, abolished the synergism between TNF-alpha and IL-9 on IL-8 release. IL-9 alone had no effect on eotaxin release into HASM cell supernatants but at concentrations of > or =10 ng/ml caused an approximately 50% increase in release of eotaxin evoked by IL-13 (10 ng/ml). U-0126 blocked the synergism between IL-9 and IL-13 on eotaxin release. IL-9 had no effect on cyclooxygenase-2 (COX-2) expression or PGE(2) release and did not augment the COX-2 expression that was induced by IL-1beta. Our results indicate that airway smooth muscle is a target for IL-9 and that IL-9 amplifies the potential for these cells to recruit eosinophils and neutrophils into the airways by a mechanism involving ERK.

IL-9 enhances the growth of human mast cell progenitors under stimulation with stem cell factor

We examined the effects of IL-9 on human mast cell development from CD34(+) cord blood (CB) and peripheral blood cells in serum-deprived cultures. IL-9 apparently enhanced cell production under stimulation with stem cell factor (SCF) from CD34(+) CB cells. A great majority of the cultured cells grown with SCF + IL-9 became positive for tryptase at 4 wk. In methylcellulose cultures of CD34(+) CB cells, IL-9 increased both the number and size of mast cell colonies grown with SCF. Furthermore, SCF + IL-9 caused an exclusive expansion of mast cell colony-forming cells in a 2-wk liquid culture of CD34(+) CB cells, at a level markedly greater than for SCF alone. Clonal cell cultures and RT-PCR analysis showed that the targets of SCF + IL-9 were the CD34(+)CD38(+) CB cells rather than the CD34(+)CD38(-) CB cells. IL-9 neither augmented the SCF-dependent generation of progeny nor supported the survival of 6-wk-cultured mast cells. Moreover, there was no difference in the appearance of tryptase(+) cells and histamine content in the cultured cells between SCF and SCF + IL-9. The addition of IL-9 increased numbers of mast cell colonies grown with SCF from CD34(+) peripheral blood cells in children with or without asthma. It is of interest that mast cell progenitors of asthmatic patients responded to SCF + IL-9 to a greater extent than those of normal controls. Taken together, IL-9 appears to act as a potent enhancer for the SCF-dependent growth of mast cell progenitors in humans, particularly asthmatic patients.

Tip60 is a co-repressor for STAT3

Tip60 (Tat-interactive protein, 60 kDa), a cellular protein with intrinsic histone acetyltransferase activity, is involved in DNA damage repair and apoptosis. Recent studies have suggested that Tip60 acts either as a co-activator or a co-repressor to modulate transcription. In this study, we demonstrate that Tip60 represses reporter gene expression when it is fused to the Gal4 DNA binding domain. We also show that Tip60 associates with histone deacetylase 7 (HDAC7) through its N-terminal zinc finger-containing region and that HDAC7 activity is required for the repressive effect of Tip60. Because endogenous Tip60 interacts with STAT3, we hypothesized that Tip60 might complex with STAT3 and HDAC7 and modulate STAT3-mediated trans-activation. Consistent with this hypothesis, the overexpression of Tip60 represses STAT3-driven reporter gene expression, which can be further potentiated by the co-transfection of HDAC7. Furthermore, interleukin-9-induced c-myc expression, which depends on STAT3 activity, is abrogated by exogenous expression of Tip60. This is the first demonstration of which Tip60 represses STAT3 activity in part through the recruitment of HDAC7.

Effects of interleukin-10 on neonatal excitotoxic brain lesions in mice

Interleukin-10 markedly reduces production of proinflammatory cytokines by activated microglia or macrophages and downregulates the expression of activating molecules on these cells. In studies performed in adults or in cell cultures, interleukin-10 protected against hypoxic-ischemic neuronal death and against lipopolysaccharide-mediated oligodendrocyte cell death. Furthermore, it was recently shown that interleukin-10 counteracts metabolic and microcirculatory effects of hypoxia-ischemia in the perinatal pig brain. Intracerebral injection of the glutamatergic analogue ibotenate to newborn mice induces cortical plate and white matter lesions mimicking the brain damage associated with cerebral palsy, and pretreatment with proinflammatory cytokines such as interleukin-1-beta or with interleukin-9 significantly exacerbates these lesions. The present study evaluated the influence of interleukin-10 on ibotenate-induced brain lesions in newborn mice under basal conditions or after exposure to cytokines. Intraperitoneal injection of interleukin-10 for 3 days following ibotenate significantly reduced the size of excitotoxic brain lesions. Intraperitoneal injection of neutralizing anti-interleukin-10 antibody for 3 days following ibotenate had no detectable effect and no difference in ibotenate-induced brain lesion size was found between wild type pups and pups deleted for the interleukin-10 gene, suggesting that endogenous interleukin-10 in newborn mice may have limited effects. Co-administration of intracerebral ibotenate and interleukin-10 had no detectable effect, arguing against a direct neuroprotective effect of interleukin-10 on neurons. While pretreatment with intraperitoneal interleukin-10 alone had no detectable effect on excitotoxic brain lesions, interleukin-10 given with interleukin-1-beta pretreatment blunted the toxic effects of interleukin-1-beta. On the other hand, combined pretreatment with IL-9 and anti-IL-10 antibody largely reversed the exacerbating effect of IL-9 on excitotoxic brain lesions. Altogether, these data suggest that, in newborn mice, exogenous interleukin-10 can be neuroprotective when acting in an inflammatory context.

Interleukin-9 induces goblet cell hyperplasia during repair of human airway epithelia

Asthma is characterized by airway inflammation, smooth muscle hyperreactivity, and airway remodeling with excessive mucus production. The effect cytokines like interleukin (IL)-9 have on airway epithelia has been addressed using murine models of asthma, as well as transgenic and knockout mice. Though highly informative, differences exist between mouse and human airway epithelia, including cellular composition (e.g., Clara cells) and stem cell/plasticity capabilities. Therefore, to address cytokine effects on human airway epithelia, we have used a primary model system to ask whether IL-9 can alter cell fates of human airway epithelia. Here, we show that IL-9 has little effect on fully differentiated ciliated human airway epithelia. However, in the setting of airway injury repair, IL-9 results in goblet cell hyperplasia. A similar response was observed when the epithelium was exposed to IL-9 before it became fully differentiated. Moreover, exposure to IL-9 resulted in increased lysozyme and mucus production by the epithelia. Thus, a combination of IL-9 and mechanical injury can explain, in part, goblet cell hyperplasia that is evident in the lungs of individuals with asthma. These data suggest that interventions that limit airway epithelial damage, block IL-9, or modulate the repair process should result in decreased airway remodeling and prevent the chronic manifestations of this disease.

Role of human interleukin-9 as a megakaryocyte potentiator in culture

OBJECTIVE

This study investigated the effect of interleukin-9 (IL-9) on the proliferation and differentiation of human colony-forming unit megakaryocytic progenitor cells (CFU-Meg).

MATERIALS AND METHODS

Peripheral blood-derived CD34(+)IL-6R(-) cells were sorted and cultured in the presence of IL-9, erythropoietin (Epo), stem cell factor (SCF), and thrombopoietin (TPO) alone or in combination. The number of pure and mixed megakaryocyte colonies, the size of pure megakaryocyte colonies, the ploidy distribution of megakaryocytes, and proplatelet formation were investigated.

RESULTS

Apart from TPO, no single factor could support CFU-Meg-derived colony formation, but each two-factor combination among IL-9, Epo, and SCF supported a few CFU-Meg colonies. Interestingly, the combination of Epo+SCF+IL-9 induced four to six times as many CFU-Meg colonies as any of the two-factor combinations. Neutralizing monoclonal antibodies (mAbs) for IL-9 receptor and c-kit completely abolished this synergistic effect. In contrast, addition of neutralizing anti-c-Mpl or anti-CXCR4 Abs did not influence colony formation, indicating that this synergistic effect was independent of TPO or SDF-1. Moreover, the endogenous production of TPO by cultured CD34(+)IL-6R(-) cells in the presence of Epo+SCF+IL-9 was ruled out by reverse transcriptase polymerase chain reaction for TPO mRNA. Interestingly, the combination of TPO, Epo, SCF, and IL-9 supported the largest number of pure and mixed megakaryocyte colonies, suggesting that this combination of cytokines might recruit primitive megakaryocytic as well as multipotential progenitors. This combination also potently enhanced proplatelet formation compared with TPO alone or a combination of Epo, SCF, and IL-9.

CONCLUSION

This study demonstrated for the first time that human IL-9 can potentiate human megakaryocytopoiesis in the presence of Epo and/or SCF.

Oxidative burst in lipopolysaccharide-activated human alveolar macrophages is inhibited by interleukin-9

Interleukin (IL)-9 is known to regulate many cell types involved in T-helper type 2 responses classically associated with asthma, including B- and T-lymphocytes, mast cells, eosinophils and epithelial cells. In contrast, target cells mediating the effects of IL-9 in the lower respiratory tract remain to be identified. Therefore, the authors evaluated the activity of IL-9 on human alveolar macrophages (AM) from healthy volunteers. AM preincubated with IL-9 before lipopolysaccharide (LPS) stimulation exhibited a decreased oxidative burst, as previously shown with IL-4. The inhibitory effect of IL-9 was abolished by anti-hIL-9R alpha monoclonal antibody, and presence of IL-9 receptors on AM was demonstrated by immunofluorescence. Both IL-4 and IL-9 failed to modulate tumour necrosis factor-alpha, IL-8 and IL-10 release by LPS-stimulated AM. However, several observations suggested that IL-9 and IL-4 act through different mechanisms: 1) interferon-gamma antagonised the IL4- but not the IL-9-mediated inhibition of AM oxidative burst; 2) expression of CD14 was downregulated by IL-4 but not by IL-9 and 3) production of tumour growth factor-beta by activated AM was potentiated by IL-9 and not by IL4, and was required for the IL-9-mediated inhibition of AM oxidative burst. These observations provide additional information concerning the activity of interleukin-9 in the lung, related to inflammatory or fibrosing lung processes.

Interleukin-2 family cytokines stimulate phosphorylation of the Pro-Ser-Pro motif of Stat5 transcription factors in human T cells: resistance to suppression of multiple serine kinase pathways

Signal transducer and activator of transcription (Stat)5a and Stat5b are critical for normal immune function. Progression of T cells through G(1)-S phase of cell cycle requires T cell receptor (TCR)- and/or cytokine-inducible tyrosine phosphorylation of Stat5a/b. Stat5a/b may also, in a cell-dependent manner, be constitutively or cytokine-inducibly phosphorylated on a Pro-Ser-Pro (PSP) motif located within the transcriptional activation domain. Phosphorylation of the PSP motif is needed for maximal transcriptional activation by Stat5, at least in certain promoter contexts. The basal and cytokine-inducible serine phosphorylation state of Stat5a/b has not been determined in T cells. Using primary human T cells and T lymphocytic cell lines coupled with novel phospho-specific antibodies to this conserved phosphoserine motif in Stat5a or Stat5b, we report that: Stat5a and Stat5b were unphosphorylated on the PSP motif under basal conditions and became markedly phosphorylated in response to several T cell growth factor stimuli, including interleukin (IL)-2, -7, -9, and -15 and phorbol ester 12-myristate 13-acetate but not TCR engagement; inducible Stat5a/b serine phosphorylation differed quantitatively and temporally; and Stat5a/b serine phosphorylation was, in contrast to inducible Stat3 serine phosphorylation, insensitive to inhibitors of mitogen-activated protein kinase, phosphatidylinositol-3 kinase, and mammalian target of rapamycin or deletion of Raf-A, -B, or -C by antisense oligonucleotides. We conclude that IL-2 family cytokines tightly control Stat5 serine phosphorylation through a kinase distinct from the Stat3 serine kinase.

Hodgkin and Reed-Sternberg cells express functional c-kit receptors and interact with primary fibroblasts from Hodgkin's disease-involved lymph nodes through soluble and membrane-bound stem cell factor

Classic Hodgkin's disease (cHD) is a lymphoid neoplasia characterized by few malignant Hodgkin and Reed-Sternberg (H-RS) cells, embedded in an abundant background of non-tumour cells. We have previously demonstrated the expression in primary H-RS cells of the receptor tyrosine kinase (RTK) c-kit; here we describe its functional role in the cross-talk between H-RS cells themselves with neighbouring cell populations. In particular, we analysed the expression of c-kit and its ligand stem cell factor (SCF) in a panel of HD-derived cell lines and fibroblasts from HD-involved lymph nodes (HDF). While c-kit was expressed by HD-derived cell lines, usually in the absence of SCF, this latter molecule, in its soluble and/or membrane-bound (mb) form, was in turn expressed at a high level by primary HDF. In vitro adhesion between HD-derived cell lines and HDF was mainly mediated by c-kit/SCF interactions, and this phenomenon was significantly inhibited by an excess of soluble SCF or by neutralizing anti-c-kit monoclonal antibodies. Furthermore, both soluble and mb-SCF increased growth and colony survival of HD-derived cell lines; these effects were significantly enhanced upon co-stimulation of H-RS cells with interleukin 9. Finally, soluble SCF was able to partially rescue H-RS cells from apoptosis induced by serum starvation. Taken together, our data indicated the expression of functional c-kit receptor by H-RS cells and suggests a role of SCF in the pathobiology of cHD.

Human bronchial epithelium expresses interleukin-9 receptors and releases neutrophil chemotactic factor

Growing evidence obtained from human genomic analysis and antigen-challenged transgenic mice suggests that interleukin-9 (IL-9) is a candidate factor in immunoglobulin E (IgE) production and thus is thought to be associated with bronchial inflammation and bronchial hyperresponsiveness (BHR). To evaluate the expression of the IL-9 receptor and its effect on the IL-9 human bronchial cell line BEAS-2B cells, reverse transcriptase-polymerase chain reaction (RT-PCR), immunohistochemical investigation, and chemotaxis assay were performed. The components of the IL-9 receptor, consisting of IL-9 receptor alpha (CD129) and IL-2 receptory ((1)132), were expressed on BEAS-2B cells as determined by RT-PCR and flow cytometry. BEAS-2B cells exposed to IL-9 released neutrophil chemotactic activity (NCA) in a time- and dose-dependent manner, and the presence of granulocyte colony-stimulating factor (G-CSF) was also detected. This factor is primarily involved in NCA for the measurement of cytokines and in the inhibition assay of neutrophil chemotaxis. These findings suggest that bronchial epithelial cells may express IL-9 receptors, and that IL-9 may induce airway inflammation through the release of G-CSF from bronchial epithelial cells.

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

Interleukin (IL)-9 is a T helper 2 cytokine implicated as a candidate gene and contributor to human asthma. We hypothesized that the inflammatory potential of bronchial epithelium is affected by its local environment and explored this hypothesis with respect to the effect of IL-9 on bronchial epithelium. We investigated the response of primary and immortalized human bronchial epithelial cells to IL-9 stimulation with respect to the release of T-cell chemoattractant factors. In response to IL-9, the HBE4-E6/E7 cell line, but not BEAS-2B cells, released the T-cell chemoattractants IL-16 and regulated on activation, normal T cells expressed and secreted (RANTES) in a dose-dependent fashion. We found a similar dose response to IL-9 in primary cells from bronchial brushings of healthy subjects and that nearly all of the T-cell chemoattraction was attributable to IL-16 and RANTES. Reverse transcriptase/polymerase chain reaction of BEAS-2B, HBE4-E6/E7, and primary cells from two subjects revealed messenger RNA for IL-9 receptor (IL-9R) alpha but not in BEAS-2B cells. Fluorescence-activated cell sorter analysis of HBE4-E6/E7 and primary cells confirmed surface expression of the IL-9 receptor. Costimulation of both cell types with IL-9 and antibody to either gamma-common chain or IL-9Ralpha completely blocked the release of T-cell chemoattractant activity, confirming the primary role of a functioning IL-9 receptor for IL-9 signaling in HBE4-E6/E7 and primary bronchial epithelial cells. We conclude that IL-9 is a stimulus for airway epithelial cell release of T-cell chemoattractant factors, which in turn may modulate the immune response in allergic airway inflammation.

Deleterious effects of IL-9-activated mast cells and neuroprotection by antihistamine drugs in the developing mouse brain

Elevated mean IL-9 serum levels have been observed in human neonates who will later develop cerebral palsy. In earlier studies, using a newborn mouse model of excitotoxic lesions mimicking those described in human cerebral palsy, we found that IL-9 pretreatment exacerbated brain damage produced by intracerebral injections of the glutamatergic analog ibotenate. Among its different cell targets, the Th2 cytokine IL-9 is a mast cell growth and differentiation factor that can cause mast cells to release various substances including histamine. In the present study, we sought to determine whether the deleterious effects of IL-9 in our mouse model were mediated by mast cells through histamine release. All mouse pups were pretreated with intraperitoneal injections of IL-9 or saline between postnatal days (P) P1 and P5. Immunohistochemistry for murine mast cell protease-1 performed on P5 showed an increased density of labeled cells in the neopallium of IL-9-treated Swiss pups as compared with controls. Western blot analysis confirmed the increased murine mast cell protease-1 brain content of IL-9-treated Swiss mice. IL-9 pretreatment had no significant effect on ibotenate-induced excitotoxic brain lesions in mast cell-deficient P5 pups (WBB6F1/J kit(W/W-v)), whereas IL-9 exacerbated these lesions in the control littermates with normal mast cell populations. Finally, cromoglycate or antihistamine drugs significantly reduced ibotenate-induced brain lesions in IL-9-treated Swiss pups. Taken together, these data suggest that recruitment of cerebral mast cells with histamine release may contribute to the exacerbation of neonatal excitotoxic brain lesions produced by IL-9. Neuroprotective strategies targeting mast cells may be useful in some neonates at risk for cerebral palsy.

Interleukin-9 reduces lung fibrosis and type 2 immune polarization induced by silica particles in a murine model

We examined the effect of interleukin (IL)-9, a cytokine active on B and T lymphocytes and associated with bronchial asthma, on the development of lung fibrosis induced by crystalline silica particles. Therefore, we compared the response to silica (1 and 5 mg/animal, intratracheally) in transgenic mice that constitutively express high levels of IL-9 (Tg5) and their wild-type counterparts (FVB). At 2 and 4 mo after treatment with silica, histologic examination and measurement of lung hydroxyproline content showed that the severity of fibrosis was significantly less important in Tg5 mice than in their wild-type counterparts. Intraperitoneal injection of IL-9 in C57BL/6 mice also reduced the amplitude of silica-induced lung fibrosis. The reduction of lung fibrosis by IL-9 was associated with a significant expansion of the B-lymphocyte population, both in bronchoalveolar lavage (BAL) and in the pulmonary parenchyma. In wild-type animals, silica-induced fibrosis correlated with markers of a T helper 2-like response such as upregulation of IL-4 levels in lung tissue and an increased immunoglobulin (Ig) G1/IgG2a ratio in BAL. Immunohistochemical studies demonstrated that the upregulation of IL-4 associated with the development of fibrosis was mainly localized in inflammatory alveolar macrophages. In transgenic mice, the level of IL-4 in lung homogenates was not significantly affected by silica treatment, and a reduced IgG1/IgG2a ratio was observed upon treatment with silica. The levels of interferon-gamma were significantly decreased after silica treatment in both strains. Together, these observations point to an antifibrotic effect of IL-9 in pulmonary fibrosis associated with a limitation of the type 2 polarization which accompanies lung fibrosis.

Interleukin-9 (IL-9) induces cell growth arrest associated with sustained signal transducer and activator of transcription activation in lymphoma cells overexpressing the IL-9 receptor

Murine interleukin (IL)-9 inhibits apoptosis in murine T lymphomas via signal transducer and activator of transcription (STAT) factors. After transfection of the human IL-9 receptor, human IL-9 had a similar antiapoptotic activity, but, unlike the mouse protein, inhibited proliferation. This effect was correlated with the level of receptor expression and the extent of STAT phosphorylation. Expression of a moderate level of suppressor of cytokine signaling 3 (SOCS3) reduced STAT activation by human IL-9 and prevented inhibition of growth but not of apoptosis. Using mutated IL-9 receptors, we showed that inhibition of proliferation was correlated with STAT1 and STAT3 activation by IL-9 and induction of the cell cycle inhibitor p19/ink4d, a STAT3 target gene. Activation of STAT1 by IFN-gamma did not result in cell growth arrest. In this model, cell growth inhibition is therefore associated with a higher number of receptors, a more robust STAT activation, and a greater sensitivity to SOCS3 expression, compared to apoptosis inhibition.

Modulation of WNT-5A expression by actinonin: linkage of APN to the WNT-pathway?

Inhibition of alanyl-aminopeptidase gene expression or enzymatic activity compromises T cell proliferation and function. Molecular mechanisms mediating these effects are not known as yet. Applying the cDNA array technique we identified the proto-oncogen Wnt-5a strongly affected by APN-inhibition. Wnt-5a and other members of the Wnt family of secreted factors are implicated in cell growth and differentiation. Wnt-5a was moderately expressed in resting T cells, but strongly down-regulated in response to activation by OKT3/IL-4/IL-9. Actinonin increased Wnt-5a-mRNA contents as confirmed by RT-PCR. In addition, expression of GSK-3 beta, an inherent component of the Wnt-pathway, was found to be increased in response to activation, but suppressed by actinonin at both the mRNA and protein level. These findings may provide a rationale for the strong growth inhibitory effects resulting from an inhibition of alanyl aminopeptidase expression or activity.

Interleukin 9 promotes influx and local maturation of eosinophils

The interleukin 9 (IL-9) pathway has recently been associated with the asthmatic phenotype including an eosinophilic tissue inflammation. The mechanism by which IL-9 affects eosinophils (eos) is not known. To investigate whether this cytokine has a direct activity on the development of eos and eosinophilic inflammation, a model of thioglycolate-induced peritoneal inflammation was used in IL-9 transgenic (TG5) and background strain (FVB) mice. In this model, a transient eosinophilic infiltration in the peritoneal cavity was observed in FVB mice 12 to 24 hours after thioglycolate injection that coincided with peak IL-5 and IL-9 release. In contrast, TG5 mice developed a massive eosinophilia that persisted at high levels (81% of total cells) even 72 hours after thioglycolate injection. Release of eosinophilic major basic protein (MBP), IL-4, and IL-5 to the peritoneal cavity of these mice was significantly increased when compared with the control FVB strain. To study the mechanism by which IL-9 exerts its effect on eos, bone marrow or peritoneal cells were cultured in the presence of IL-5, IL-9, or their combination in vitro. IL-5 alone was able to generate significant numbers of eos in TG5 but not FVB mice, whereas a combination of IL-5 and IL-9 induced marked eosinophilia in both strains indicating a synergism between these 2 cytokines. These data suggest that IL-9 may promote and sustain eosinophilic inflammation via IL-5-driven eos maturation of precursors.

Interleukin (IL)-4/IL-9 and exogenous IL-16 induce IL-16 production by BEAS-2B cells, a bronchial epithelial cell line

Previous studies have suggested that bronchial epithelial cells may perpetuate airway inflammation. We have reported that the bronchial epithelial cell line BEAS-2B can produce interleukin (IL)-16, a potent chemoattractant for CD4+ T cells. IL-16 is thought to regulate airway inflammation in asthmatics. Recent studies showed that IL-4 induces inflammatory cytokines in bronchial epithelial cells and that IL-9 is a candidate gene for development of asthma. The present study demonstrated that BEAS-2B cells produced specifically IL-16 by synergistic effects of IL-4 + IL-16, or IL-9 + IL-16, and that the synthesized IL-16 induced migration of CD4+ T cells. This study is a first report indicating that IL-16 production may be maintained by an autocrine machinery by epithelial cell-derived IL-16 with IL-4 and IL-9 in asthma.

Interleukin 9 induces expression of three cytokine signal inhibitors: cytokine-inducible SH2-containing protein, suppressor of cytokine signalling (SOCS)-2 and SOCS-3, but only SOCS-3 overexpression suppresses interleukin 9 signalling

Interleukin 9 (IL-9) is a cytokine preferentially produced by T helper type 2 lymphocytes and active on various cell types such as T- and B-lymphocytes, mast cells and haemopoietic progenitors. The IL-9 receptor (IL-9R) belongs to the haemopoietic receptor superfamily and its signal transduction involves mainly the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. Here we studied the implication of a novel family of suppressors of cytokine signalling (called CIS, for cytokine-inducible SH2-containing protein, and SOCS, for suppressor of cytokine signalling) in IL-9 signal attenuation. In BW5147 T-cell lymphoma, IL-9 induced the rapid expression of CIS, SOCS-2 and SOCS-3 with a peak after 2 h of stimulation. Using IL-9R mutants, we showed that STAT activation is required for CIS/SOCS induction: CIS and SOCS-2 expression was induced either via STAT1 and/or STAT3 or via STAT5 but only STAT1 and/or STAT3 were involved in SOCS-3 expression. The effect of these three proteins on IL-9 signal transduction was assessed by transient transfection in HEK-293 cells expressing the components of the IL-9 signalling pathway and a STAT-responsive reporter construct. These experiments showed that only SOCS-3 is able to inhibit IL-9-induced signal transduction; neither CIS nor SOCS-2 exerted any effect. Stable transfection of CIS and SOCS-3 in BW5147 lymphoma cells showed that only overexpression of SOCS-3 had an inhibitory activity on STAT activation, gene induction and the anti-apoptotic activity of IL-9. By contrast, CIS failed to affect the IL-9 response.

Reversible expression of tryptases in continuous L138.8A mast cells

It has been established that mast cells can alter their expression of granule chymases and tryptases in vivo. In vitro, a reversible cytokine regulation has so far only been demonstrated for chymases. We now show a reversible and cytokine-regulated expression of the tryptases MMCP-6 and MMCP-7 and of the chymases MMCP-1, MMCP-2 and MMCP-4 in the continuous murine mast cell line L138.8A. The L138.8A mast cells lacked expression of mRNA for mast cell-specific proteases when cultured in IL-3, and only 49% and 41% of the cells were c-kit+ and FcepsilonRI+, respectively, by flow cytometry. Kit-ligand/stem cell factor induced synthesis of the chymase MMCP-4 and the tryptases MMCP-6 and MMCP-7 and increased the fraction of c-kit+ and FcepsilonRI+ L138.8A cells to >70%. Kit-ligand-induced tryptase expression was suppressed in the presence of IL-3 or IL-9, and reversed after withdrawal of kit-ligand. IL-9 or IL-3/IL-10 promoted the formation of Alcian blue+ granules and increased the fraction of c-kit+ and FcepsilonRI+ L138.8A cells to >90%. IL-9 further induced the expression of the chymases MMCP-1, MMCP-2 and MMCP-4. Thus, the immature mast cell line L138.8A has the capacity to modulate both tryptase and chymase expression and represents the first model system to analyze the molecular regulation of tryptase expression in vitro.

Interleukin-9 enhances interleukin-5 receptor expression, differentiation, and survival of human eosinophils

Interleukin-9 (IL-9) has been implicated in the pathogenesis of allergic disorders. To examine the interaction between IL-9 and eosinophils, we evaluated mature peripheral blood eosinophils for their expression of the specific alpha-subunit of the IL-9 receptor (IL-9R-alpha). The expression of IL-9R-alpha by human eosinophils was detected at the messenger RNA (mRNA) and protein levels by reverse transcriptase-polymerase chain reaction (RT-PCR), flow cytometry, and immunocytochemical analysis, respectively. Functional analyses demonstrated that recombinant human (rh)IL-9 inhibited in vitro peripheral blood human eosinophil apoptosis in a concentration-dependent manner. We then examined the role of IL-9 in eosinophil differentiation using the human cord blood CD34(+) cells and human promyelocytic leukemia cells (HL-60). The addition of IL-9 to CD34(+) cells cultured in IL-3 and IL-5 enhanced eosinophil development, and IL-9 alone induced the expression of IL-5R-alpha. IL-9 also up-regulated the IL-5R-alpha chain cell surface expression during terminal eosinophil differentiation of the HL-60 cell line. Our findings suggest that IL-9 may potentiate in vivo eosinophil function by increasing their survival and IL-5-mediated differentiation and maturation. Taken together, these results suggest a mechanism by which IL-9 potentiates airway and tissue eosinophilia.

Rescue of human T cells by interleukin-9 (IL-9) from IL-2 deprivation-induced apoptosis: correlation with alpha subunit expression of the IL-9 receptor

Interleukin-9 (IL-9) is a Th2-derived cytokine that uses the gamma-chain of the IL-2 receptor for signaling. Therefore, the responsiveness of human Th1 and Th2 cell clones to IL-9 was measured by examining the ability of this cytokine to prevent apoptosis induced by IL-2 deprivation. A time course study demonstrated that both subsets of T cell clones underwent apoptosis with similar kinetics when deprived of IL-2 and that viability could be maintained by the addition of either IL-4 or IL-7. Interestingly, IL-9 prevented apoptosis in only 2 (Th2) of 14 clones tested. Analysis of IL-9R alpha subunit expression on 18 T cell clones revealed that IL-9 responsiveness was directly proportional to the expression of the high-affinity receptor. IL-9 responsiveness was also dependent on long-term culturing because neither freshly isolated nor 3-day phytohemagglutinin (PHA)-stimulated peripheral blood lymphocytes (PBL) expressed IL-9R alpha. In summary, the data showed that IL-9 can rescue only a small subset of Th2 cells from apoptosis induced by growth factor withdrawal and that expression of IL-9R alpha is required for the antiapoptotic signals mediated by this cytokine.

Anti-IL-9 vaccination prevents worm expulsion and blood eosinophilia in Trichuris muris-infected mice

Production of neutralizing anti-IL-9 antibodies was induced in mice by immunization with mouse IL-9 coupled to ovalbumin. In the six mouse strains tested, a strong and long-lasting anti-IL-9 response developed with seric inhibitory titers of 10(-3) to 10(-5), as measured in an in vitro IL-9-dependent cell proliferation assay. In vivo, this immunization completely abrogated the increase in mast-cell protease-1 levels as well as the eosinophilia observed in mice after implantation of an IL-9-secreting tumor. We took advantage of this method to assess the role of IL-9 in infections with nematode Trichuris muris, where IL-9 production correlates with the resistant phenotype. C57BL/6 mice, which normally expel the parasite, became susceptible after anti-IL-9 immunization, demonstrating that IL-9 plays a critical role in this model. In addition, neutralization of IL-9 also inhibited parasite-induced blood eosinophilia. Taken together, the present data demonstrate the potency of our strategy to antagonize IL-9 in vivo and shows that this cytokine plays a major role in resistance against T. muris infection.

Distinct roles for STAT1, STAT3, and STAT5 in differentiation gene induction and apoptosis inhibition by interleukin-9

Interleukin-9 (IL-9) activates three distinct STAT proteins: STAT1, STAT3, and STAT5. This process depends on one tyrosine of the IL-9 receptor, which is necessary for proliferation, gene induction, and inhibition of apoptosis induced by glucocorticoids. By introduction of point mutations in amino acids surrounding this tyrosine, we obtained receptors that activated either STAT5 alone or both STAT1 and STAT3, thus providing us with the possibility to study the respective roles of these factors in the biological activities of IL-9. Both mutant receptors were able to prevent apoptosis, but only the mutant that activated STAT1 and STAT3 was able to support induction of granzyme A and L-selectin. In line with these results, constitutively activated STAT5 blocked glucocorticoid-induced apoptosis. In Ba/F3 cells, significant proliferation and pim-1 induction were observed with both STAT-restricted mutants, though proliferation was lower than with the wild-type receptor. These results suggest that survival and cell growth are redundantly controlled by multiple STAT factors, whereas differentiation gene induction is more specifically correlated with individual STAT activation by IL-9.

Interleukin-9-induced expression of M-Ras/R-Ras3 oncogene in T-helper clones

In an attempt to gain insight into the molecular mechanisms involved in interleukin-9 (IL-9) activities, representational difference analysis (RDA) was used to identify messages that are induced by IL-9 in a murine T-helper-cell clone. One of the isolated genes encodes for the newly described M-Ras or R-Ras3, which is part of the Ras gene superfamily. M-Ras expression was found to be induced by IL-9 but not IL-2 or IL-4 in various murine T-helper-cell clones, and this induction seems to be dependent on the JAK/STAT pathway. Contrasting with the potent upregulation of M-Ras expression, M-Ras was not activated by IL-9 at the level of guanosine triphosphate/guanosine diphosphate (GTP/GDP) binding. However, IL-3 increased GTP binding to M-Ras, suggesting that M-Ras induction might represent a new mechanism of cooperativity between cytokines such as IL-3 and IL-9. Constitutively activated M-Ras mutants induced activation of Elk transcription factor by triggering the MAP kinase pathway and allowed for IL-3-independent proliferation of BaF3 cells. Taken together, these results show that cytokines such as IL-9 can regulate the expression of a member of the RAS family possibly involved in growth-factor signal transduction.

IL-9 induces chemokine expression in lung epithelial cells and baseline airway eosinophilia in transgenic mice

Recent data have identified IL-9 as a key cytokine in determining susceptibility to asthma. These data are supported by the finding that allergen-exposed IL-9-transgenic mice exhibit many features that are characteristic of human asthma (airway eosinophilia, elevated serum IgE and bronchial hyperresponsiveness) as compared to the background strain. A striking feature of these animals is a robust peribronchial and perivascular eosinophilia after allergen challenge, suggesting that IL-9 is a potent factor in regulating this process. In an attempt to gain insights into the molecular mechanism governing IL-9 modulation of lung eosinophilia, we investigated the ability of this cytokine to induce the expression of CC-type chemokines in the lung because of their effect on stimulating eosinophil chemotaxis. Here we show that IL-9-transgenic mice in contrast to their congenic controls exhibit baseline lung eosinophilia that is associated with the up-regulation of CC-chemokine expression in the airway. This effect appears to be through a direct action of IL-9 because the addition of recombinant IL-9 to primary epithelial cultures and cell lines induced the expression of these chemokines in vitro. These data support a mechanism for IL-9 in regulating the expression of eosinophil chemotactic factors in lung epithelial cells.

Interleukin-9 regulates NF-kappaB activity through BCL3 gene induction

BCL3 encodes a protein with close homology to IkappaB proteins and interacts with p50 NF-kappaB homodimers. However, the regulation and transcriptional activity of BCL3 remain ill-defined. We observed here that interleukin-9 (IL-9) and IL-4, but not IL-2 or IL-3, transcriptionally upregulated BCL3 expression in T cells and mast cells. BCL3 induction by IL-9 was detected as soon as 4 hours after stimulation and appeared to be dependent on the Jak/STAT pathway. IL-9 stimulation was associated with an increase in p50 homodimers DNA binding activity, which was mimicked by stable BCL3 expression. This contrasts with tumor necrosis factor (TNF)-dependent NF-kappaB activation, which occurs earlier, involves p65/p50 dimers, and is dependent on IkappaB degradation. Moreover, IL-9 stimulation or BCL3 transient transfection similarly inhibited NF-kappaB-mediated transcription in response to TNF. Taken together, our observations show a new regulatory pathway for the NF-kappaB transcription factors through STAT-dependent upregulation of BCL3 gene expression.

A novel function for transforming growth factor-beta1: upregulation of the expression and the IgE-independent extracellular release of a mucosal mast cell granule-specific beta-chymase, mouse mast cell protease-1

Intestinal mucosal mast cells (IMMC) express granule neutral proteases that are regulated by T-cell-derived cytokines, including interleukin-3 (IL-3) and IL-9, and by stem cell factor (SCF). The IMMC-specific chymase, mouse mast cell protease-1 (mMCP-1), is released in substantial quantities into the blood stream during gastrointestinal allergic responses. We used cultured bone marrow-derived mast cells (mBMMC) to identify cytokines that regulate the expression and extracellular release of mMCP-1. When grown in IL-3-rich WEHI (15% vol/vol) and 50 ng/mL recombinant rat SCF (rrSCF) bone marrow cells supplemented with IL-9 (5 ng/mL) differentiated into mBMMC that expressed a maximum of less than 250 ng mMCP-1/10(6) cells and 189 ng mMCP-1/mL of culture supernatant. Supplementation of the same three cytokines with transforming growth factor-beta1 (TGF-beta1; 1 ng/mL) resulted in substantially enhanced expression (6 micrograms/10(6) mBMMC) and extracellular release (2 micrograms/mL of culture supernatant) of mMCP-1. The response to TGF-beta1 was dose-dependent, with maximal effect at 1 ng/mL, and was associated with immunohistochemical and ultrastructural changes in the secretory granules. IL-9-induced expression of mMCP-1 may be due to endogenously expressed TGF-beta1, because it was blocked by anti-TGF-beta antibodies. In conclusion, the expression and extracellular release of the IMMC-specific chymase, mMCP-1, is strictly regulated by TGF-beta1.