title: Markers of respiratory inflammation in horses in relation to seasonal changes in air quality in a conventional racing stable.
abstract: Airborne factors in a conventionally managed racing stable and markers of pulmonary inflammation in the stabled horses were investigated on 3 occasions at 6-month intervals, including 2 winter periods and the intervening summer period. The stable measurements included inside and outside ambient temperature and relative humidity, levels of total and respirable dust, endotoxin, and 1,3-beta-glucan. Horses (n = 12) were examined in detail clinically as well as by endoscopy, bronchoalveolar lavage (BAL) cytology, and real-time polymerase chain reaction (RT-PCR) analysis of BAL-cells for IL-6 and IL-10 mRNA. Indoor measurements showed low dust levels irrespective of season. Inhalable dust, as well as 1,3-beta-glucan, were higher during the winter stabling period, whereas endotoxin levels were higher during summer. Complete data from all sampling occasions to be used for further evaluation was obtained for only 8 of the horses. There was a trend for elevation of BAL neutrophils in the horses during winter stabling that coincided with a 3.7-fold increased expression of IL-6 mRNA in BAL cells (P = 0.014). Compared to summer sampling, IL-10 mRNA expression was significantly upregulated in only 1 of the winter sampling occasions, implicating influence on immune regulation by factor/s apart from seasonal differences. Our findings suggest up-regulation of innate immunity in the airways of stabled horses; in particular involving IL-6 in association with mild elevations in respirable dust, 1,3-beta-glucan, and/or cold ambient air. However, given that this study was observational, other unmeasured environmental factors associated with winter stabling need to be considered.
authors.affiliation: Department of Clinical Sciences, Equine Internal Medicine, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: Miia
authors.initials: M
authors.lastname: Riihimäki
authors.forename: Amanda
authors.initials: A
authors.lastname: Raine
authors.forename: Lena
authors.initials: L
authors.lastname: Elfman
authors.forename: John
authors.initials: J
authors.lastname: Pringle
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis*; D000818:Animals; D018893:Bronchoalveolar Lavage / Q000662:veterinary; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D004391:Dust / Q000032:analysis; D004731:Endotoxins / Q000032:analysis; D005260:Female; D006734:Horse Diseases / Q000276:immunology* / Q000378:metabolism; D006736:Horses; D006799:Housing, Animal / Q000592:standards*; D007249:Inflammation / Q000276:immunology / Q000378:metabolism / Q000662:veterinary; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D008173:Lung Diseases, Obstructive / Q000276:immunology / Q000378:metabolism / Q000662:veterinary*; D008297:Male; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D012621:Seasons; D013696:Temperature
chemical_list: D004391:Dust; D004731:Endotoxins; D015850:Interleukin-6; D012333:RNA, Messenger; D016753:Interleukin-10