Comparison of long-term exposure of C57BL/6 female mice´s lungs to three different types of cigarette smoke available in Brazil

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is caused primarily by the inhalation of cigarette smoke, a very complex mixture of some 9000+ constituents. The continuous inhalation of cigarette smoke is known to trigger impairment in pulmonary elasticity and airway-parenchymal remodeling. Some studies have suggested that women are more susceptible to the effects of tobacco smoke than men, leading to more severe disease for the equivalent quantity of cigarettes consumed. As there are different types of cigarette commonly smoked in Brazil and there is a great need of studies in female subjects, we designed a long-term exposure of C57BL/6 female mice's lungs to three different types of cigarettes available in Brazil (two filtered and one unfiltered). Methods: Exposure experiments were conducted for 60 sequential days, each group (n= 10 mice) exposed to 12 cigarette a day divided into three sessions. The three different types of cigarette were: commercial cigarette “Marlboro”(MG), Fumo de Corda cigarette without filter brand “Souza Paiol”(SPG), and Fumo de Corda cigarette with filter brand “3 Lobos” (LG), while the forth group was the control group (CG). For histological analysis, were selected all animals in each group. Results: Lung tissue samples from animals exposed to SPG and MG showed significant increase septal interstitium thickness when compared to LG and CG. Collagen fibers were significantly increased in septal interstitium of SPG animals compared to CG. Interestingly, a significant decrease in collagen fibers of septal interstitium was found in MG group coincident with increased hyperdistension of the alveoli when compared to compared to CG group. In bronchiole from animals exposed to MG tobacco, a significant increase of mucinous PAS+ positive cells were found when compared to CG, SPG and LG. Conclusions: This lung pathology specimens study have showed differences in the effects produced by long-term exposure to different kind of cigarettes in female mice.