Endothelin-1 concentrations in bronchoalveolar lavage fluid of cats with experimentally induced asthma.

Abstract

BACKGROUND: There is a need for biomarkers for diagnosis, therapeutic monitoring, and prognosis for asthma in cats. Endothelin-1 (ET-1) is implicated in the pathogenesis of inflammatory airway diseases in other species but not the cat. OBJECTIVE: To conduct a prospective experimental study to show that experimentally asthmatic cats, but not control cats without airway inflammation, would have increased concentrations of ET in BALF. ANIMALS: Eleven healthy, adult research cats. METHODS: Prospective experimental study. Six healthy cats without airway inflammation were used as controls. Asthma was induced using Bermuda grass allergen (BGA) in 5 cats. Collection of BALF for total nucleated cell and differential counts was performed. The concentration of ET-1 in cell-free BALF samples was determined. Data were analyzed using a Mann-Whitney U-test with P < .05 considered significant. RESULTS: The median [range] BALF total cell numbers, eosinophil numbers, and eosinophil percentages were significantly higher in the cats following experimental induction of asthma (1,870 cells/&#x3bc;L [1,450-3,440], 711 cells/&#x3bc;L [356-1,686] and 38% [20-49]) compared to baseline control parameters (462 cells/&#x3bc;L [239-780], 18 cells/&#x3bc;L [18-62] and 3.5% [0-8]) (P < .01). The median [range] BALF ET concentration was also significantly higher after induction of asthma (1.393 fmol/mL[0.977-2.247]) compared to healthy control cats (0.83250 fmol/mL [0.625-1.038]) (P = .012). CONCLUSIONS AND CLINICAL IMPORTANCE: This study suggests that BAL ET-1 concentration can be used to differentiate normal cats from those with experimentally induced asthma. If the same holds true for cats with naturally developing asthma, BAL ET-1 may prove a useful diagnostic biomarker for asthma.