The relationship between alveolar epithelial proliferation and airway obstruction after ozone exposure.

BACKGROUND

Proliferating cell nuclear antigen (PCNA) is a component of multiprotein complexes that are expressed during cell proliferation. Ozone induces cell necrosis and a consequent increase in cell proliferation.

METHODS

To investigate the effects of acute ozone inhalation on cell proliferation and airway obstruction in BALB/C mice, we examined enhanced pause (Penh) as an index of airway obstruction and PCNA expression by immunohistochemical staining.

RESULTS

Compared with controls that received filtered air, the ozone-exposed groups had increased PCNA expression in the alveolar epithelial cells. In rank order, the highest PCNA index was found following 2.0 p.p.m. ozone exposure. In the 2.0 p.p.m. ozone group, there was a PCNA index of 16.83 +/- 0.57% (mean +/- SEM; P< 0.01), compared with 4.25 +/- 0.5% at 0.12 p.p.m., 6.83 +/- 0.60 at 0.5 p.p.m and 12.16 +/- 0.48% at 1 p.p.m. Following ozone exposure, Penh was increased in a dose-dependent manner. There was a significant correlation between the PCNA index in alveoli and Penh (r = 0.63, P< 0.01).

CONCLUSIONS

These data suggest that ozone can induce alveolar epithelial cell proliferation in a dose-dependent manner, and that alveolar epithelial cell proliferation is correlated with airway obstruction.