Tissue transglutaminase can be involved in airway inflammation of toluene diisocyanate-induced occupational asthma

Background: This study was conducted to evaluate whether tissue transglutaminase (tTG) may be involved in airway inflammation of toluene diisocyanate-induced occupational asthma (TDI-OA). Methods: We enrolled 93 patients with TDI-OA, 177 asymptomatic exposed subjects, 43 patients with allergic asthma, and 70 unexposed normal controls. The prevalence of serum immunoglobulin G (IgG) to tTG in the TDI-OA group (20.2%) was significantly higher than that in the three other groups (P<0.001). Results: TDI-OA patients with serum IgG to tTG had significantly lower methacholine PC ₂₀ values (P<0.02) and significantly higher prevalence of specific immunoglobulin E to vapor type TDI-human serum albumin conjugate (P<0.01; r ²=0.411, P<0.05). TDI exposure could increase tTG activity via reactive oxygen species (ROS) production, which was found to cross-link with cytokeratin 19 on immunoblot analysis. Conclusion: Therefore, TDI exposure may activate tTG via ROS-mediated mechanism in the airway epithelium leading to persistent airway inflammation in TDI-OA patients.