EQUINE | Abstracts
Exhaled breath condensate hydrogen peroxide, pH
and leukotriene B4 are associated with lower airway
inflammation and airway cytology in the horse
S. du Preez S. L. Raidal G. S. Doran M. Prescott K. J. Hughes
First published: 19 June 2018
Background
Exhaled breath condensate (EBC) analysis is a
noninvasive method to assess the lower respiratory
tract. In human subjects, EBC hydrogen peroxide
(H2O2), pH and leukotriene B4 (LTB4) 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.
Results
EBC pH and H2O2 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 LTB4
(P<0.05). Ambient temperature, relative humidity
and assay methodology significantly impacted some
analytes.
Main limitations
Prospective, cross‐sectional study. 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.
Methods Conclusions
Study design
Clinical, endoscopic and airway cytological findings
from 47 horses were compared with EBC pH and
concentrations of H2O2 and LTB4 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.
14
EBC pH and H2O2 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.
• Equine Health Update •
https://doi.org/10.1111/evj.12979