Type I allergic diseases such as allergic rhinitis are caused by IgE-mediated humoral immune responses, while eosinophils also fulfill important roles in the etiology of IgE-mediated allergy. IL-21 regulates growth, differentiation, and function of T, B, and NK cells, while the production of IgE is also influenced by IL-21. In this study we examined whether IL-21 is capable of controlling IgE-mediated allergic reactions in vivo by using the allergic rhinitis mouse model that was established by repetitive sensitization and intranasal challenge with OVA. Intranasal administration with recombinant mouse IL-21 (rmIL-21) significantly reduced the number of sneezes, as well as the serum concentration of OVA-specific IgE, in comparison with that of untreated allergic mice. The rmIL-21 treatment also suppressed germline Cε transcription in the nasal-associated lymphoid tissues, which may have, at least partly, resulted from the up-regulation of Bcl-6 mRNA caused by IL-21. Local expression of IL-4, IL-5, and IL-13 was also inhibited by the intranasal cytokine therapy whereas, in contrast, the expression of endogenous IL-21 mRNA was induced by exogenous rmIL-21. Moreover, IL-21 acted on nasal fibroblasts to inhibit production of eotaxin. This novel function of IL-21 may be associated with the attenuation of eosinophil infiltration into nasal mucosa that was revealed by histopathological observation. These results indicated that IL-21 nasal administration effectively ameliorated allergic rhinitis through pleiotropic activities, i.e., the prevention of IgE production by B cells and eotaxin production by fibroblasts.

IL-21 exerts pleiotrophic immunomodulatory activities on a variety of target cells including B cells that undergo class switch recombination (CSR) to IgE. In this study, we examined whether IgE-mediated systemic anaphylaxis was controlled by in vivo administration of IL-21 using the peanut allergy model in mice and investigated the molecular mechanisms underlying the IL-21-induced regulation of IgE. The anaphylactic reaction was completely abolished by the administration of recombinant mouse IL-21 or an IL-21 expression plasmid in terms of the change of body temperature and anaphylactic symptoms. The recombinant mouse IL-21 treatment remarkably suppressed IgE CSR in splenic B cells, resulting in significant decrease in serum concentrations of total as well as allergen-specific IgE. In the meanwhile, IL-21 provoked B cells in normal as well as allergic mice to express the inhibitor of differentiation 2 (Id2) gene that was shown to be crucially involved in the regulation of the activation-induced cytidine deaminase and IgE CSR. Moreover, mice genetically deficient for Id2 were completely unsusceptible to IL-21-induced prevention of IgE CSR and anaphylaxis. The present study strongly suggests that IL-21 is capable of regulating systemic allergic reactions by inducing the transcriptional regulator Id2, and the cytokine may be useful for clinical intervention for allergic diseases including anaphylaxis.

Background: An association between bronchial asthma and sinusitis has long been suspected. Our aim is to study the clinical features of chronic sinusitis associated with bronchial asthma as two manifestations of one airway disease. Methods: We conducted a prospective analysis of the outcome of 88 patients, with or without bronchial asthma, who underwent endoscopic sinus surgery (ESS) for chronic sinusitis. Patients were divided into two groups by the presence or absence of asthma and were evaluated. One surgeon performed the ESS, and the same postoperative treatment was given to both groups. The postoperative outcomes of symptoms and objective findings related to sinusitis were evaluated numerically, with a maximum score of 2 points for each examination item. Twenty-eight patients with asthma symptoms were assessed before and after surgery, using peak flow (liter/second) and medication scores (according to US Food and Drug Administration) to determine whether bronchial asthma was improved by first-time ESS. Results: The outcomes of ESS were signifi- cantly worse in the asthma group, especially the endonasal findings. Patients suffering from chronic sinusitis and bronchial asthma showed improvement following ESS in terms of their asthma symptoms, peak flow and medication score. Patients with a good ESS result tended to have the greatest improvement in their asthma. Conclusions: We conclude that sinusitis and asthma are closely related to each other, acting as two manifestations of one airway disease. We recommend treating cases of sinusitis complicated by asthma as a single disease of the entire respiratory tract.

We investigated regulatory mechanisms of Cl(-) secretion playing an essential role in the maintenance of surface fluid in human airway epithelial Calu-3 cells. The present study reports that quercetin (a flavonoid) stimulated bumetanide-sensitive Cl(-) secretion with reduction of apical Cl(-) conductance, suggesting that quercetin stimulates Cl(-) secretion by activating an entry step of Cl(-) across the basolateral membrane through Na(+)/K(+)/2Cl(-) cotransporter (NKCC1). To clarify the mechanism stimulating NKCC1 by quercetin, we verified involvement of protein kinase (PK)A, PKC, protein tyrosine kinase (PTK), and cytosolic Ca(2+)-dependent pathways. A PKA inhibitor (PKI-14-22 amide), a PKC inhibitor (Gö 6983) or a Ca(2+) chelating agent did not affect the quercetin-stimulated Cl(-) secretion. On the other hand, a PTK inhibitor (AG18) significantly diminished the stimulatory action of quercetin on Cl(-) secretion without inhibitory effects on apical Cl(-) conductance, suggesting that a PTK-mediated pathway is involved in the stimulatory action of quercetin. The quercetin action on Cl(-) secretion was suppressed with brefeldin A (BFA, an inhibitor of vesicular transport from ER to Golgi), and the BFA-sensitive Cl(-) secretion was not observed in the presence of an epidermal growth factor receptor (EGFR) kinase inhibitor (AG1478), suggesting that quercetin stimulates Cl(-) secretion by causing the EGFR kinase-mediated translocation of NKCC1 or an NKC1-activating factor to the basolateral membrane in human airway epithelial Calu-3 cells. However, the surface density of NKCC1 was not increased by quercetin, but quercetin elevated the activity of NKCC1. These observations indicate that quercetin stimulates Cl(-) secretion by activating NKCC1 via translocation of an NKCC1-activating factor through an EGFR kinase-dependent pathway.

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