Oxidative stress has been implicated in the pathogenesis of
bronchial asthma. Besides granulocytes, the airway epithelium can produce large amounts of
reactive oxygen species and can contribute to
asthma-related oxidative stress.
Histamine is a major inflammatory mediator present in large quantities in asthmatic airways. Whether
histamine triggers epithelium-derived oxidative stress is unknown. We therefore aimed at characterizing human airway epithelial H2O2 production stimulated by
histamine. We found that air-liquid interface cultures of primary human bronchial epithelial cells (BECs) and an immortalized BEC model (Cdk4/hTERT HBEC) produce H2O2 in response to
histamine. The main source of airway epithelial H2O2 is an
NADPH dual oxidase,
Duox1. Out of the four
histamine receptors (H1R-H4R), H1R has the highest expression in BECs and mediates the H2O2-producing effects of
histamine.
IL-4 induces
Duox1 gene and
protein expression levels and enhances
histamine-induced H2O2 production by epithelial cells. Using HEK-293 cells expressing
Duox1 or
Duox2 and endogenous H1R,
histamine triggers an immediate intracellular
calcium signal and H2O2 release. Overexpression of H1R further increases the oxidative output of Duox-expressing HEK-293 cells. Our observations show that BECs respond to
histamine with Duox-mediated H2O2 production. These findings reveal a mechanism that could be an important contributor to oxidative stress characteristic of asthmatic airways, suggesting novel therapeutic targets for treating asthmatic airway disease.