title: Breath condensate hydrogen peroxide correlates with both airway cytology and epithelial lining fluid ascorbic acid concentration in the horse.
abstract: The relationship between hydrogen peroxide (H2O2) concentration in expired breath condensate (EBC) and cytology of the respiratory tract obtained from tracheal wash (TW) or bronchoalveolar lavage (BAL), and epithelial lining fluid (ELF) antioxidant status is unknown. To examine this we analysed the concentration of H2O2 in breath condensate from healthy horses and horses affected by recurrent airway obstruction (RAO), a condition considered to be an animal model of human asthma. The degree of airway inflammation was determined by assessing TW inflammation as mucus, cell density and neutrophil scores, and by BAL cytology. ELF antioxidant status was determined by measurement of ascorbic acid, dehydroascorbate, reduced and oxidised glutathione, uric acid and alpha-tocopherol concentrations. RAO-affected horses with marked airway inflammation had significantly higher concentrations of breath condensate H2O2 than control horses and RAO-affected horses in the absence of inflammation (2.0 +/- 0.5 micromol/l. 0.4 +/- 0.2 micromol/l and 0.9 +/- 0.2 micromol/l H2O2, respectively; p < 0.0001). The concentration of breath condensate H2O2 was related inversely to the concentration of ascorbic acid in ELF (r = -0.80; p < 0.0001) and correlated positively with TW inflammation score (r = 0.76, p < 0.0001) and BAL neutrophil count (r = 0.80, p < 0.0001). We conclude that the concentration of H2O2 in breath condensate influences the ELF ascorbic acid concentration and provides a non-invasive diagnostic indicator of the severity of neutrophilic airway inflammation.
authors.affiliation: Centre for Equine Studies, Animal Health Trust, Lanwades Park, Kentford, Suffolk CB8 7UU, UK. chris.deaton@aht.org.uk
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Deaton
authors.forename: David J
authors.initials: DJ
authors.lastname: Marlin
authors.forename: Nicola C
authors.initials: NC
authors.lastname: Smith
authors.forename: Ken C
authors.initials: KC
authors.lastname: Smith
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Newton
authors.forename: Susan M
authors.initials: SM
authors.lastname: Gower
authors.forename: Susan M
authors.initials: SM
authors.lastname: Cade
authors.forename: Colin A
authors.initials: CA
authors.lastname: Roberts
authors.forename: Pat A
authors.initials: PA
authors.lastname: Harris
authors.forename: Robert C
authors.initials: RC
authors.lastname: Schroter
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Kelly
mesh_terms: D000402:Airway Obstruction / Q000175:diagnosis* / Q000473:pathology; D000818:Animals; D001205:Ascorbic Acid / Q000032:analysis* / Q000378:metabolism; D001944:Breath Tests / Q000379:methods*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D001999:Bronchoscopy; D002452:Cell Count; D003683:Dehydroascorbic Acid / Q000032:analysis / Q000378:metabolism; D003937:Diagnosis, Differential; D004195:Disease Models, Animal; D005978:Glutathione / Q000032:analysis / Q000378:metabolism; D006736:Horses; D006861:Hydrogen Peroxide / Q000032:analysis* / Q000378:metabolism; D007249:Inflammation / Q000175:diagnosis / Q000378:metabolism; D009093:Mucus / Q000166:cytology; D009504:Neutrophils / Q000166:cytology; D020545:Respiratory Mucosa / Q000737:chemistry; D012137:Respiratory System / Q000473:pathology; D013053:Spectrophotometry
chemical_list: D006861:Hydrogen Peroxide; D005978:Glutathione; D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid