Local expression of IL-4 and IL-5 in perennial allergic rhinitis and their modulation by topical corticosteroid therapy.

Perennial allergic rhinitis (PAR) is an increasing problem for which new and exciting therapies are being developed. A T(H)2-polarized cytokine pattern is thought to predominate regulating local IgE synthesis and cell recruitment in PAR and the development of intranasal steroids has resulted in several agents with quick actions, localized effects and great efficacy in its management. The aim of work was to determine the differences in the local expression of IL-4 and IL-5 in patients with PAR compared to non-atopic healthy controls and investigate the relationship between the expression of these cytokines and the clinical aspects of the disease. Also to evaluate local expression of these cytokines in some of these patients before and after treatment with intranasal steroids (fluticasone proprionate). Nasal biopsies from 37 patients with PAR before therapy and from 8 of them after receiving corticosteroids as local nasal spray were taken. PAR was confirmed by a history of perennial nasal blockage, discharge, and/or sneeze for at least 2 years before the study and by positive skin prick test. Also nasal biopsies were taken from 20 age and gender matched non-atopic controls. Biopsies were analyzed using a reverse transcription-polymerase chain reaction (RT-PCR) to investigate local expression of IL-4 mRNA. Enzyme immunoassay was used for estimation of IL-5 levels in the nasal mucosa. By using the ROC curve; (11 pg/ml) was estimated as a cut-off value for IL-5 where levels below this cut off were considered negative. This study showed that the most common causative allergens in PAR were mite dust, followed by wool & pigeon then mixed moulds. There was a significant relation between expression of IL-4 and IL-5 and the occurrence of allergic rhinitis where mRNA of IL-4 was detected in 17/37 [46%] of patient group and in 3/20 (15%) of the control group (P < 0.05). IL-5 levels were more than the calculated cut off value in 22/37 (59.5%) of patient group as compared to 4/20 (20%) in the control group (P < 0.01). Also a high significant association was found between IL-4 & IL-5 (P < 0.01) in patient group. However, no significant relation was found between signs & symptoms of AR or patients' age or gender and cytokines expression. Corticosteroid nasal spray treatment showed a significant reduction in IL-4 gene expression and IL-5 positivity (P < 0.05). It is concluded that IL-4 & IL-5 have an important role in the pathogenesis of PAR and corticosteroid nasal spray is effective in exerting an immunomodulatory activity by reducing IL-4 & IL-5 expression.