Abstract
BackgroundOsteopontin (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.MethodsSubjects 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.ResultsOPN 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%).ConclusionOPN 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.
Highlights
Osteopontin (OPN) is a multifunctional cytokine that has been primarily investigated in Th1 diseases
The most intense staining was observed in epithelial and endothelial cells, and in the subepithelial layer to a lesser extent. Previous studies on these nasal biopsies have shown a clear increase in the number of EG2+ cells over the pollen season and no increase with fluticasone propionate (FP) treatment
To determine if the expression of OPN is related to the change in eosinophil numbers previously seen in the allergic rhinitis (AR) nasal biopsies, the staining was compared to the EG2+ cell counts previously obtained [2]
Summary
Osteopontin (OPN) is a multifunctional cytokine that has been primarily investigated in Th1 diseases. It has been implicated in Th2-mediated allergic diseases, such as asthma. 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 inflammation in the nose [2] and increases cytokine release [1]. OPN is a pleiotropic cytokine normally expressed by many cell types [7], which has been implicated in various diseases [8], including asthma [9,10,11] and chronic rhinosinusitis [12]. Studies of OPN expression have quantified the expression in different ways, including concentrations in lavage fluid, the expression of OPN mRNA by RT-PCR and the semi-quantification of cells expressing OPN by immunohistochemistry
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