By: 1 March 2013

Copyright © Igor Korionov – Fotolia

Foetuses and premature babies exposed to cigarette smoke are at a greater risk of developing childhood respiratory diseases, such as asthma.

Research presented at the ANESTHESIOLOGY 2012 annual meeting revealed cigarette smoke adversely affects the developing human airway, especially in prematurity.

“Due to their highly immature lungs, premature babies often require high levels of additional oxygen in the neonatal intensive care unit, which can put these babies at higher risk for life-long problems with lung diseases,” said study author Elizabeth Vogel, M.D., Department of Anaesthesiology, Mayo Clinic, Rochester, Minn.

Additional exposure to second-hand smoke in the home often precipitates further respiratory problems and possible return trip(s) to the ICU.

“By examining human foetal airway cells from gestational ages during which rapid airway and lung growth would normally occur, we hope to understand how the developing airway is particularly susceptible to cigarette smoke with the goal of developing interventions to prevent downstream problems such as asthma and bronchopulmonary dysplasia,” said Dr Vogel.

The human foetal airway smooth muscle cells of deceased 18-to-20-week human foetuses were exposed to various levels of cigarette smoke. Gel analysis was used to determine changes in caveolae and their proteins, cell proliferation and death. Changes in the level of calcium were examined using fluorescent Ca2+ sensitive dyes and real-time microscopic imaging. Cells exposed to cigarette smoke had increased levels of calcium and caveolar proteins, similar to the effects of inflammation in asthma. Even low levels of cigarette smoke increased markers of cell proliferation, while higher smoke levels caused cell death.

These results indicate that the detrimental effects of cigarette smoke are caused, at least in part, by altered caveolar signaling in developing airway smooth muscle cells. Increased caveolar proteins, calcium and cell proliferation can make the airways thicker and more responsive to bronchoconstrictors, thus increasing airway contractility, making it more difficult for the baby to breathe. Such detrimental changes would be only more problematic in premature babies with an immature respiratory system and weak chest walls.

The authors report that future studies will rely on a combination of human cell-based work and appropriate animal models to gain a better understanding of how cigarette smoke influences the developing airway.