Influx of neutrophils and persistence of cytokine expression in airways of horses after performing exercise while breathing cold air.
OBJECTIVE
To determine effects of exercise performed while breathing cold air on expression of cytokines and influx of neutrophils in airways of horses.


METHODS
9 adult horses.


METHODS
In a crossover study, bronchoalveolar lavage fluid (BALF) was obtained 24 and 48 hours after each of 2 submaximal exercise sessions performed by horses while breathing warm (25 degrees C) or cold (-5 degrees C) air. Total and differential nucleated cell counts were determined for each BALF sample. Relative mRNA expression of cytokines in BALF cells was quantified by use of a reverse transcription-PCR assay.


RESULTS
Horses had a modest but significant influx of neutrophils into the airways 24 hours after a single exercise session while breathing cold air. No other cell types were increased at 24 or 48 hours after exercising while breathing cold air. Continued increases in expression of cytokines interleukin (IL)-5 and-10 as well as proinflammatory cytokines IL-1, -6, and -8 were detected 24 hours after exercising while breathing cold air. Forty-eight hours after exercising while breathing cold air, expression of IL-10 was still higher than that for IL-10 after horses exercised while breathing warm air. Expression of tumor necrosis factor-alpha was significantly increased at 48 hours after exercising while breathing cold air.


CONCLUSIONS
Exposure of intrapulmonary airways to cold air alters immunologic responses of horses for at least 48 hours. The increased expression of cytokines that suppress cell-mediated immunity may predispose athletes to viral infections of the respiratory tract following exercise in cold weather.
Davis
Michael S
MS
Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA.
Williams
Caroline C
CC
Meinkoth
James H
JH
Malayer
Jerry R
JR
Royer
Christopher M
CM
Williamson
Katherine K
KK
McKenzie
Erica C
EC
D000388:Air; D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D003080:Cold Temperature; D016207:Cytokines / Q000378:metabolism*; D005260:Female; D008168:Lung / Q000378:metabolism*; D008297:Male; D009504:Neutrophils / Q000378:metabolism*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism
D016207:Cytokines; D012333:RNA, Messenger