Tissue Transglutaminase Can Be Involved in Airway Inflammation of Toluene Diisocyanate-Induced Occupational Asthma

Abstract

This study was conducted to evaluate whether tissue transglutaminase (tTG) may be involved in airway inflammation of toluene diisocyanate-induced occupational asthma (TDI-OA). 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). 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. Therefore, TDI exposure may activate tTG via ROS-mediated mechanism in the airway epithelium leading to persistent airway inflammation in TDI-OA patients.