O’Neil et al. Allergy, Asthma & Clinical Immunology 2010, 6:28 http://www.aacijournal.com/content/6/1/28 R E S E A R C H ALLERGY, ASTHMA & CLINICAL IMMUNOLOGY Open Access Quantitative expression of osteopontin in nasal mucosa of patients with allergic rhinitis: effects of pollen exposure and nasal glucocorticoid treatment Serena E O’Neil1*, Carina Malmhäll1, Konstantinos Samitas2, Teet Pullerits1, Apostolos Bossios1, Jan Lötvall1 Abstract Background: Osteopontin (OPN) is a multifunctional cytokine that has been primarily investigated in Th1 diseases. Recently, it has also been implicated in Th2-mediated allergic diseases, such as asthma. The expression of OPN in allergic rhinitis (AR) is currently unknown, as is the effect of intranasal glucocorticosteroids (GCs) on that expression. Methods: Subjects with AR were randomised to receive treatment with fluticasone propionate (FP) (n = 12) or a placebo (n = 16) over the grass pollen season and nasal biopsies were taken prior to, and during the season. OPN expression in the nasal mucosa was examined with immunohistochemistry. Healthy non-AR controls (n = 5) were used as a comparator. Results: OPN expression was detected in epithelial cells, subepithelial infiltrating/inflammatory cells and cells lining the vessels and glands of all subjects. Comparison of the pre- and peak-pollen season biopsy sections in placebo treated patients revealed no increase in OPN expression during the grass pollen season (5.7% vs 6.4%). Treatment with a local glucocorticosteroid did not alter the expression of OPN during pollen exposure (6.2% vs 6.7%). Conclusion: OPN has been increasingly associated with the pathogenesis of various Th2-mediated diseases. However, our finding that the OPN expression in the nasal mucosa of AR patients is not significantly affected by allergen exposure and is comparable to that of the healthy controls, suggests that intracellular OPN is not directly involved in the pathogenesis of allergic rhinitis. Background The inflammatory process in allergic rhinitis (AR) involves many different inflammatory cells, cytokines, chemokines and other regulatory molecules [1]. It is well known that exposure to allergens, including natural pollen exposure, primarily enhances eosinophilic inflam- mation in the nose [2] and increases cytokine release [1]. Furthermore, local glucocorticoids are efficient in attenuating the allergen-induced inflammation and the cytokine expression, as we and others have documented in nasal mucosal studies [2-6]. * Correspondence: serena.oneil@lungall.gu.se 1Krefting Research Centre, Sahlgrenska Academy, University of Gothenburg, Sweden Full list of author information is available at the end of the article OPN is a pleiotropic cytokine normally expressed by many cell types [7], which has been implicated in var- ious diseases [8], including asthma [9-11] and chronic rhinosinusitis [12]. OPN can be expressed in eosino- phils, which could argue its involvement in allergic eosi- nophilic inflammation [13]. Studies of OPN expression have quantified the expression in different ways, includ- ing concentrations in lavage fluid, the expression of OPN mRNA by RT-PCR and the semi-quantification of cells expressing OPN by immunohistochemistry. The aim of the current study was to determine the level and tissue distribution of OPN expression in the nasal mucosa of patients with AR and to determine whether OPN expression is affected by allergen exposure during a grass pollen season in allergic individuals. We also aimed to investigate whether a nasal glucocorticoid affected © 2010 O’Neil et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.