Effects of in vitro exposure to hay dust on expression of interleukin-23, -17, -8, and -1β and chemokine (C-X-C motif) ligand 2 by pulmonary mononuclear cells from horses susceptible to recurrent airway obstruction

Abstract

To examine gene expression of selected cytokines in pulmonary mononuclear cells isolated from healthy horses and horses susceptible to recurrent airway obstruction (RAO), and to determine whether interleukin (IL)-17 and IL-23 were associated with pulmonary inflammation. 6 RAO-susceptible and 5 healthy horses. Bronchoalveolar lavage cells were retrieved from horses that were stabled and fed dusty hay for 24 hours. Lavage cells devoid of neutrophils were incubated for 24 hours with solutions of PBS, hay dust, lipopolysaccharide, or B-glucan. Gene expression of IL-17, IL-23 (p19 and p40 subunits), IL-8, IL-1B, chemokine (C-X-C motif) ligand 2 (CXCL2), and B-actin was measured by use of real-time reverse transcription PCR assays. The degree of inherent expression of target genes in bronchoalveolar lavage cells treated with PBSS was not different between the 2 groups of horses. Relative to exposure to PBSS, exposure to the hay dust solution increased gene expression of all cytokines more than 2-fold in cells from both groups of horses, but the magnitudes of these increases were not different between the groups. Exposure to lipopolysaccharide solution increased gene expression of IL-8, CXCL2, and IL-1B in cells from RAO-susceptible horses, but this increase was not significantly different from that in cells from control horses. Exposure to B-glucan solution failed to increase gene expression in cells from either horse group, compared with gene expression when cells were exposed to PBSS. The acute pulmonary neutrophilia characteristic of RAO was not associated with an increase in upregulation of gene expression of chemokines in pulmonary mononuclear cells from disease-susceptible horses.