Background and objective Carbon monoxide (CO) is known to be present in mea
surable quantities in the exhalation of asthmatic patients. Corticosteroid
treatment resulted in a decrease in exhaled CO levels in asthmatic patients
, raising the possibility that an increase in exhaled CO concentration refl
ects inflammation of the asthmatic airway. Heme oxygenase-1 (HO-1) protein,
also called HSP32, is the rate-limiting enzyme in the catabolism of heme t
o biliverdin, free iron and CO. However, it is unknown whether an expressio
n of HO-1 within the lung tissue is related to allergic airway inflammation
. We studied the expression of HO-1 in lung tissue and bronchoalveolar lava
ge cells in a mouse model of asthma.
Methods Ovalbumin (OVA)-sensitized C57BL/6 mice were challenged with aeroso
lized OVA. HO-1 positive cells were identified by immunostaining in lung ti
ssue and bronchoalveolar lavage fluid (BALF) after the challenge.
Results HO-1 positive cell numbers increased in the subepithelium of the br
onchi after OVA challenge. In cytospin preparations from BALF after OVA cha
llenge, HO-1 was localized to alveolar macrophages. Inside the macrophages,
HO-1 reactivity was expressed in the cytoplasm, and the perinuclear region
Conclusion The expression of HO-1 is increased within the lung tissue in al
lergic airway inflammation. Measurement of HO-1 activity may be clinically
useful in the management of asthma.