Involvement of Eosinophils in the Early-Phase Allergic Reaction in a Guinea Pig Rhinitis Model

Abstract

Background: Eosinophils are found in the nasal lavage fluid (NLF) and nasal biopsies of patients with allergic rhinitis after a nasal antigen challenge, and associated not only with a late-phase allergic reaction (LPR) but also an early phase allergic reaction (EPR). Numerous studies have been carried out to clarify the participation of eosinophils in LPR or airway hyperresponsiveness. However, there has been no published report describing in detail the role of eosinophils during EPR. To better understand the involvement of eosinophils in EPR, we studied the effects of repeated antigen challenges on nasal airway responsiveness and eosinophilic inflammation in EPR using a guinea pig rhinitis model. Methods: Nasal airway responsiveness was measured as the nasal airway resistance (NAR) after nasal antigen provocation. Eosinophilic inflammation during EPR was assessed by nasal lavage and histopathological examination using two groups of animals: those in group 1 were subjected to a sensitization pretreatment only, and those in group 2 were subjected to a pretreatment of sensitization followed by repeated nasal challenges. Results: Repeated antigen challenges induced nasal hyperresponsiveness as indicated by a decrease in the antigen provocation dose and a significant increase in NAR. Furthermore, significant increases in eosinophil counts, eosinophil peroxidase (EPO) activity and protein content in NLF during EPR were observed following antigen provocation in group 2. There were significant correlations between the levels of these parameters, and albumin was the most prevalent of the proteins in NLF. Histopathological examination showed that the degree of eosinophil infiltration into the lamina propria of the nasal mucosa of the animals in group 2 was significantly and apparently higher than in group 1. Particularly, epithelial disruption and mucosal edema were significantly elevated after antigen provocation in group 2. Conclusions: These results suggest that chronic eosinophil accumulation is induced by repeated antigen challenges in the nasal tissue, and that once antigen provocation occurs, eosinophils in the tissue are activated and responsible for the amplification of EPR such as vascular permeability and mucosal edema.

Dissection of Antigen-Specific Humoral and Cellular Immune Responses for the Development of Experimental Immune-Mediated Blepharoconjunctivitis in C57BL/6 Mice

“…In fact, LPR was induced by transfer of Ag-specific IgE in the lung 13 and skin 14 of mice and nose of guinea pigs. 15 Yet, it has not been demonstrated that Ag-specific IgE alone can induce LPR in the conjunctiva. Our data is the first to demonstrate that LPR is inducible in the conjunctiva by Ag-specific IgE.…”

Characterization of Anti-Inflammatory Properties and Evidence for No Sedation Liability for the Novel Antihistamine SUN-1334H

“…Of these cells, eosinophils are most invariably found infiltrated in the tissues during allergic inflammation and hence considered as hallmark of allergic inflammatory diseases [2,3,4]. Eosinophils are also the principal cells entering nasal secretions in the early-phase response [5]. Severity of symptoms of allergic rhinitis and asthma can be correlated with the degree of eosinophilia in the nose and sputum [6].…”

Intranasal immunization with phosphorylcholine suppresses allergic rhinitis in mice

“…14,15 Furthermore, in the present study, the levels of serum IgE and eosinophil infiltration into the nasal mucosa were significantly decreased by intranasal PC pretreatment similar to the experiments using pneumococcal vaccines. 14,15 Because eosinophils enhance hyper-responsiveness and vascular permeability, 21 the suppression of nasal symptoms and mucosal swelling observed in those studies might be due to decreased eosinophil infiltration into the nasal mucosa.…”