Biological responses in rats exposed to mainstream smoke from a heated cigarette compared to a conventional reference cigarette

Abstract

The heated cigarette (HC) generates mainstream smoke by vaporizing the components of the tobacco rod using a carbon heat source at the cigarette tip. Mainstream smoke of HC contains markedly less chemical constituents compared to combusted cigarettes. Mainstream smoke from HC was generated under Health Canada Intense regimen and its biological effects were compared to those of Reference (3R4F) cigarettes, using nose-only 5-week and 13-week inhalation studies. In the 13-week study, SD rats were necropsied following exposure to mainstream smoke from each cigarette at 200, 600 or 1000 µg wet total particulate matter/L for 1 h/day, 7 days/week or following a 13-week recovery period. Histopathological changes in the respiratory tract were significantly lesser in HC groups; e.g. respiratory epithelial hyperplasia in the nasal cavity and accumulation of pigmented macrophages in alveoli. After a 13-week recovery, the lesions were completely or partially regressed, except for accumulation of pigmented macrophages in alveoli, in both HC and 3R4F groups. In the 5-week study, SD rats were necropsied following exposure to mainstream smoke of either cigarette at 600 or 1000 µg/L for 1 h, two times/day (with 30 min interval), 7 days/week or following a 4-week recovery period. Bronchoalveolar lavage fluid (BALF) analysis of neutrophil percentages and enzyme levels like γ-GT, ALP and LDH indicated that pulmonary inflammation was significantly less in HC groups compared to 3R4F groups. In conclusion, HC demonstrated significantly lower biological effects compared to 3R4F, based on the BALF parameters and histopathology.

Mimetic peptide AC2-26 of annexin A1 as a potential therapeutic agent to treat COPD

“…Other research using a rat-COPD model [10] indicated that daily cigarette smoke exposure for 2 h during 5 weeks promoted respiratory lesions similar to those observed in the 13 weeks exposure time. Reduced body weight and significant increases in neutrophil counts were also found after 5-weeks of exposure [10].…”

“…The significant increases in airspace enlargement after 4 and 12 weeks of tobacco smoke exposure were similar, and an increase in total leukocytes recovered from bronchoalveolar lavage (BAL) was also showed after 4 weeks of tobacco smoke exposure [9]. Other research using a rat-COPD model [10] indicated that daily cigarette smoke exposure for 2 h during 5 weeks promoted respiratory lesions similar to those observed in the 13 weeks exposure time. Reduced body weight and significant increases in neutrophil counts were also found after 5-weeks of exposure [10].…”

“…Higher blood pressure and weight loss are commonly observed in patients with COPD [1,4]. The impact of cigarette smoke on weight gain was also observed in another research using a rat-COPD model of 5 weeks exposure to cigarette smoke [10]. Concerning the respiratory alterations, studies indicate that patients with thicker lung walls related to emphysema or COPD present severe clinical conditions and airflow limitation with compromised lung function [41].…”

“…COPD is presented according to the progressive intensity of the smoking habit [8]. However, in animal models, it has been reported that the reduction in the time of exposure to tobacco associated with increasing of the cigarettes number per day produces similar results to those found by long-term exposure [9][10][11]. In a rat model of COPD [9], after 4 weeks of tobacco smoke exposure for 6 h a day and 3 days a week, signs of alveolar damage and the presence of neutrophils within the lung parenchyma were observed.…”

Hyperplasia of Wistar rat tongue mucosa due to exposure to cigarette side-stream smoke

“…The common etiology of OSCC is tobacco use in its various forms (22%). [6][7][8][9] Dental Journal (Majalah Kedokteran Gigi) p-ISSN: 1978-3728; e-ISSN: 2442-9740. Accredited No.…”