Human bronchial epithelial cell dysfunction following in vitro exposure to nitrogen dioxide

Abstract

Nitrogen dioxide (NO2), is a major air pollutant, that causes bronchoconstriction and bronchial hyperreactivity, and may also lead to damage and inflammation of the airway epithelium. We have cultured human bronchial epithelial cells and investigated the effect of exposure to NO2, for 20 min on epithelial cell membrane integrity and function in vitro. Epithelial cell membrane damage and permeability were assessed by release of 51Cr from prelabelled cells, and movement of 14C-labelled bovine serum albumin (BSA) across the bronchial epithelial cell monolayers. Ciliary beat frequency (CBF) of the cells was monitored by the analogue contrast enhancement technique, and arachidonic acid (AA) metabolism was investigated by analysis of radiolabelled AA metabolites generated from cultures prelabelled by incubation with [3H]-arachidonic acid. Exposure to 400 and 800 parts per billion (ppb) NO2 significantly increased the release of 51Cr from 0.9 +/- 0.4%, in control cultures exposed to 5% CO2 in air, to 9.7 +/- 3.2% and 13.9 +/- 3.5%, respectively. Similarly, NO2 also significantly increased the movement of 14C-BSA across the epithelial monolayers from 1.3 +/- 0.2%, in control cultures, to 2.7 +/- 0.2%, 3.8 +/- 0.4% and 5.1 +/- 0.5%, respectively, in cultures exposed to 100, 400 and 800 ppb NO2. Although NO2 attenuated the CBF of the cells at all concentrations investigated, this was significant only at the concentration of 2,000 ppb NO2.(ABSTRACT TRUNCATED AT 250 WORDS)