Methylation of free-floating deoxyribonucleic acid fragments in the bronchoalveolar lavage fluid of dogs with chronic bronchitis exposed to environmental tobacco smoke.
BACKGROUND
The etiology of canine chronic bronchitis (CB) is not completely understood, although exposure to environmental tobacco smoke (ETS) affects the airway inflammatory responses in some dogs with CB. The mechanism by which this occurs is unknown.


RESULTS
We investigated the concentrations and methylation rates of free-floating DNA fragments in bronchoalveolar lavage fluid (BALF) from dogs with chronic bronchitis. Based on serum cotinine levels, dogs with CB were divided into 2 groups: dogs that either had or had not been exposed to ETS. Our results demonstrated that the total nucleated cell and macrophage numbers increased in BALF of ETS-exposed dogs with CB. There were no significant differences in DNA concentrations and methylation rates in BALF between the 2 groups. However, 3 out of 8 dogs exposed to ETS had high DNA methylation rates in their BALF samples.


CONCLUSIONS
Our results suggest that ETS exposure leads to epigenetic modifications of cellular components in BALF in dogs diagnosed with CB.
Laboratory of Comprehensive Veterinary Clinical Studies, Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Kameino 1866, Fujisawa, Kanagawa Japan.
Yoshiki
Y
Yamaya
Laboratory of Veterinary Biochemistry, Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Kameino 1866, Fujisawa, Kanagawa Japan.
Hiroshi
H
Sugiya
Laboratory of Comprehensive Veterinary Clinical Studies, Department of Veterinary Medicine, College of Bioresource Sciences, Nihon University, Kameino 1866, Fujisawa, Kanagawa Japan.
Toshihiro
T
Watari
Chronic bronchitis; DNA methylation; Dog; Second-hand smoke