Glutathione S-transferase P1 Ile105Val polymorphism modulates allergen-induced airway inflammation in human atopic asthmatics in vivo

Background Glutathione S-transferase P1 is a Phase II cytoprotective and detoxifying enzyme that is widely expressed in human airways. The glutathione S-transferase P1 Ile105Val polymorphism has been linked with atopic disorders and asthma. Yet, little remains known about the regulation of allergic inflammation by glutathione S-transferase P1 in human asthmatics. Objective To establish the effect of the glutathione S-transferase P1 Ile105Val polymorphism on allergen-induced airway inflammation and oxidant stress, and non-specific bronchial hyperresponsiveness to methacholine and reactivity to specific allergen in mild human atopic asthmatics in vivo. Methods Five Val105/Val105, twelve Val105/Ile105 and twenty Ile105/Ile105 mild atopic asthmatics underwent methacholine challenge, inhaled allergen challenge and endobronchial allergen provocation through a bronchoscope. A panel of inflammatory cytokines and chemokines, F2-isoprostanes and isofuranes, markers of oxidative stress, thromboxane B2 and immunoglobulin E were measured in bronchoalveolar lavage fluid at baseline and 24h after allergen instillation. Results Asthmatics with glutathione S-transferase P1 Val105/Val105 compared with asthmatics with the glutathione S-transferase P1 Val105/Ile105 and Ile105/Ile105 had greater generation of acute phase cytokines (TNF-, IL-6, CXCL8), IL-12, CCL11, thromboxane B2 and immunoglobulin E at 24h after local allergen challenge. The GSTP1 genotype had no effect on airway hyperresponsiveness to methacholine and the reactivity to specific allergen. Conclusion The glutathione S-transferase P1 Ile105Val polymorphism markedly modifies allergen-provoked airway inflammation in atopic asthmatics in vivo. Modulation of the biochemical milieu in response to allergen provides a mechanistic explanation for regulatory effects of glutathione S-transferase P1 polymorphism on airway pathophysiology, and may guide improvement of future therapeutic methods in human atopic asthmatics. These findings must me confirmed in a larger study population of asthmatics with various ethnicities.