Expression data from lipopolysaccharide treated and untreated equine alveolar macrophages and basal comparison with peritoneal macrophages

Alveolar macrophages are the first line of defense against pathogens in the lungs of all mammalian species and therefore may constitute an appropriate therapeutic target cell in the treatment and prevention of opportunistic airway infections. Analysis of alveolar macrophages from several species has revealed a unique cellular phenotype and transcriptome, presumably linked to their distinct airway environment and function in host defense. The current study extends these findings to the horse. Firstly, the transcriptome of equine alveolar macrophages was compared to that of equine peritoneal macrophages. This comparison revealed the differential basal expression of 451 genes. Gene expression analysis revealed an alternative macrophage polarisation profile in alveolar macrophages and a hybrid macrophage activation profile in peritoneal macrophages, a phenomenon potentially attributable to a degree endotoxin tolerance. Secondly, the change in gene expression profile of equine AMs following lipopolysaccharide stimulation was investigated. This revealed a significant change in the expression of 240 genes, including well known upregulated inflammatory genes. Equine untreated alveolar and peritoneal macrophages, as well as six hours lipopolysaccharide treated alveolar macrophages were used for RNA extraction and hybridization on Affymetrix microarrays. We sought to characterise the specific biology of the equine alveolar macrophage, we analysed the basal gene expression of equine alveolar macrophages and made comparisons with (a) the basal gene expression of an alternative macrophage population (peritoneal macrophages) and (b) the LPS-induced gene expression of equine alveolar macrophages.