Using a human microarray to highlight new genes of interest for a better understanding of molecular mechanisms that underpin the physiopathology of heaves

Environmental causes of heaves are well described, but the molecular mechanisms of the disease remain unclear. Using reverse transcription polymerase chain reaction (RT-PCR), disparate results have been obtained concerning cytokines expression profile. cDNA microarray appears to be so far the platform of choice for massively parallel gene expression profiling and provides a good tool for exploratory research. However, equine-specific microarrays are not yet available on the market. Because they are commercially available, highly specific and well annotated, human and mouse large-scale microarrays are an exploratory alternative to equine-specific microarrays. In the present study, the purpose was to highlight new targets not previously related to the disease and able to improve our understanding of the molecular mechanisms of the disease. A human microarray was used to study gene expression in nucleated cells originating from peripheral blood and bronchoalveolar lavage fluid in heaves-affected horses. With a four-fold cut-off, a total of 46 candidates were identified with differentially regulated genes between heaves-affected horses and controls. Based on their documented function, five of these genes were selected for the real-time quantitative RT-PCR (RT-qPCR) validation procedure: CYBB, BTG1, MARCKS, PTX3 and PTPRC. The RT-qPCR results confirmed those obtained with the microarray, pointing out these genes as new directions for future experiments. However, the human microarray failed to detect the presence of IL-1beta and Il-8, otherwise confirmed by RT-qPCR, and the expression profile of the disease could not be obtained