Aerosolized substance P protects against cigarette-induced lung damage and tumor development

Both first-hand and second-hand [i.e. side-stream cigarette smoke (SSCS)] exposure to cigarette smoke is known to damage the lungs, alter the immune system, and predispose individuals to the development of emphysema and lung cancer. Previous work from these laboratories has demonstrated that administration of aerosolized substance P (SP) was capable of protecting the pulmonary and immune systems from damage due to environmental toxicants (e.g. hydrocarbon exposures). In the present study, the effects of SP on SSCS exposure were examined. Treatment of mice exposed to SSCS with aerosolized SP prevented pathological cellular and functional changes in the lung as reflected by prevention of damage to airway basement membranes/endothelial cells and preservation of normal airway dynamic compliance. Further, SP treatment reduced and/or prevented the occurrence of micronuclei formation in cells isolated from mice exposed in vivo to SSCS (an indicator of DNA/genetic damage). Finally, in an experimental in vivo lung cancer model, SP therapy significantly reduced the numbers of lung tumors, increased animal survival, and activated pulmonary immune defense mechanisms. Thus, aerosolized SP therapy appears to be capable of inhibiting preventing and/or reversing the cellular and genetic precursors of emphysema and malignancy that often result from exposure to cigarette smoke.