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Exhaled breath condensate hydrogen peroxide, pH and leukotriene B 4 are associated with lower airway inflammation and airway cytology in the horse
Author(s) -
du Preez S.,
Raidal S. L.,
Doran G. S.,
Prescott M.,
Hughes K. J.
Publication year - 2019
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.12979
Subject(s) - exhaled breath condensate , bronchoalveolar lavage , eosinophil , medicine , gastroenterology , airway , respiratory tract , nasal lavage , horse , chemistry , immunology , asthma , respiratory system , lung , allergy , anesthesia , biology , paleontology
Summary Background Exhaled breath condensate ( EBC ) analysis is a noninvasive method to assess the lower respiratory tract. In human subjects, EBC hydrogen peroxide (H 2 O 2 ), pH and leukotriene B 4 ( LTB 4 ) are useful for detection and monitoring of inflammatory lung diseases, including asthma. Objectives To determine associations between EBC biomarkers and cytological and endoscopic definitions of lower airway inflammation ( LAI ) while controlling for sampling and environmental variables. Study design Prospective, cross‐sectional study. Methods Clinical, endoscopic and airway cytological findings from 47 horses were compared with EBC pH and concentrations of H 2 O 2 and LTB 4 by univariate and multivariable analyses. Dichotomous (presence/absence of airway inflammation) and continuous outcome variables (differential cell counts in tracheal aspirate and bronchoalveolar lavage fluid, BALF ) were evaluated and potential effects of collection and methodological factors were included. Results EBC pH and H 2 O 2 concentrations were higher in horses with LAI and both were positively associated with the percentage of neutrophils in BALF (P<0.05). Mast cell percentage in BALF was negatively associated with EBC pH , and BALF eosinophil percentage was positively associated with EBC LTB 4 (P<0.05). Ambient temperature, relative humidity and assay methodology significantly impacted some analytes. Main limitations LAI is challenging to categorise due to a variety of clinical and cytological phenotypes. Although the study was designed to overcome this limitation, numbers of horses were small in some categories. Conclusions EBC pH and H 2 O 2 concentrations are altered by airway inflammation, suggesting a role for these biomarkers in the diagnosis and monitoring of airway disease. Environmental and methodological factors can influence these biomarkers and should be considered in the interpretation of results.