Am. J. Respir. Cell Mol. Biol.,
Volume 20, Number 6, June, 1999 1238-1250
Cigarette Smoke Potentiates House Dust Mite Allergen-Induced
Increase in the Permeability of Human Bronchial Epithelial Cells In Vitro
Csaba
Rusznak,
Raymond J.
Sapsford,
Jagdish L.
Devalia,
R.
Justin John,
Ellen L.
Hewitt,
Alan G.
Lamont,
Alan J.
Wood,
Samir S.
Shah,
Robert J.
Davies,
and
Stefan
Lozewicz
Academic Department of Respiratory Medicine, St. Bartholomew's and the Royal London School of Medicine
and Dentistry; and Department of Cardiovascular Surgery, The London Chest Hospital, London; and Peptide
Therapeutics plc, Cambridge, United Kingdom
Although studies have suggested that exposure to cigarette smoke (CS) may be associated with the development of atopy, the mechanisms underlying this are not clearly understood. It has been suggested that CS
impairs the barrier function of the airway epithelium, leading to increased access of allergens such as those of the house dust mite (HDM) Dermatophagoides pteronyssinus (Der p) to antigen-presenting cells, with
subsequent allergic sensitization. In order to test this hypothesis, we established primary explant cultures
of human bronchial epithelial cells (HBEC) in cell culture inserts, and exposed these for 20 min, 1 h, 3 h,
and 6 h to CS or air in the absence or presence of 300 ng/ml Der p, and then further incubated the cultures
over a period of 24 h. The HBEC cultures were assessed for changes in permeability as measured by
changes in: (1) electrical resistance (ER); and (2) passage of 14C-labeled bovine serum albumin (14C-BSA)
and Der p allergens across the HBEC cultures. We also assessed the effects of protease inhibitors and the
antioxidant glutathione (GSH) in this experimental system. Damage to HBEC cultures was assessed by the
release of [51Cr]sodium chromate from prelabeled cells, and by release of lactate dehydrogenase (LDH).
Twenty minutes of exposure to CS as compared with exposure to air did not significantly alter either the
ER or passage of 14C-BSA across the HBEC cultures. In contrast, incubation with Der p led to a significant increase in the permeability of HBEC cultures, an effect that was enhanced by exposure to CS but
was abrogated by the specific protease inhibitors and GSH. Passage of Der p was also increased by exposure to CS. Exposure of HBEC cultures to CS led to a significant release of 51Cr and LDH from these cells
as compared with cells exposed to air. This effect was augmented further when HBEC cultures were incubated with Der p. Exposure of HBEC cultures for 1 h, 3 h, and 6 h to CS led to a markedly significant
dose- and time-dependent increase in the permeability of these cells. These results suggest that exposure to
CS significantly enhances Der p-induced decreases in electrical resistance and the increased passage
across HBEC cultures of 14C-BSA and of the Der p allergen itself.
