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.

IFN-gamma secretion by CD8T cells inhibits allergen-induced airway eosinophilia but not late airway responses.

BACKGROUND: CD8+T cells can suppress allergen-induced late airway responses (LARs) and airway inflammation. OBJECTIVE: To test the hypothesis that the suppression of LARs and airway eosinophilia by CD8+T cells is IFN-gamma mediated, we tested the effects of adoptively transferred CD8+T cells, in which IFN-gamma synthesis was inhibited by an antisense (AS) oligodeoxynucleotide (ODN), on the airway responses of a rat model of allergic asthma. METHODS: CD8+T cells were harvested from the cervical lymph nodes of ovalbumin (OVA)-sensitized Brown Norway rats for administration to other actively sensitized syngeneic rats. CD8+T cells (2 x 10(6)) were incubated for 6 hours with 2 micromol/L AS ODN or sense ODN and were injected intraperitoneally into recipients; inhibition of IFN-gamma expression in vitro by AS ODN was shown by means of flow cytometry. Two days later, rats were challenged with aerosolized OVA. RESULTS: OVA-induced LAR and bronchoalveolar lavage (BAL) fluid eosinophilia were suppressed by sense ODN-treated CD8+T cells. IFN-gamma expression in BAL cells was elevated in these animals. IFN-gamma expression in BAL cells was at control levels in recipients of AS ODN-treated CD8+ cells, confirming the success of the AS treatment in vivo. BAL eosinophilia was also largely restored in the AS ODN treatment group. In contrast, the CD8+T cell-induced suppression of the LAR was not significantly affected by AS ODN pretreatment. CONCLUSIONS: These results indicate that CD8+T cells inhibit airway eosinophilia through secretion of IFN-gamma but may suppress the LAR by means of other mechanisms.