Transcriptome analysis of porcine PMBCs after stimulation by LPS or PMA/ionomycin using SLA-RI/NRSP8-13K chip

Background: During the past 25 years, selection of production traits highly increased pig production but diseases have emerged that may cause economic loss of extreme importance. Designing sustainable animal production that better balances productivity with resistance to disease is a major concern and challenge for the next decade. In order to address questions related to immunity and resistance to disease, it is necessary to increase knowledge on the pig immune system and to produce efficient tools dedicated to this species. In this context we produced a generic array enriched in immunity genes and validated its relevance by studying innate immune response of pigs by stimulating porcine mononuclear cells with lipopolysaccharide (LPS) or a mixture or phorboml myristate acetae (PMA) and ionomycin for 24 hours. Results: A long oligonucleotide-based chip was produced by combining a generic set of 13K probes targeting 8541 genes to a newly designed SLA-RI set that targets all genes and pseudogenes of the pig major histocompatibility complex region (SLA complex) in both orientations (906 probes) and immunity genes outside the SLA complex (2957 porbes). The porcine chip was referred to as SLA-RI/NRSP8-13K. Transcripotme analysis of PBMCs stimulated by LPS or PMA/ionomycin was carried out. Ten times more genes were up regulated after PMA/ionomycin stimulation by comparison to LPS stimulation. The LPS response was more related to the catalog Diseases and Disorders and the PMA/ionomycin response to the catalog Molecular and Cellular Function. LPS stimulation induced a general inflammation response with over-expression of SAA1, pro-inflammatory chemokines IL8, CCL2, CXCL5, CXCL3, CXCL2 and CCL8 as well as genes related to oxidative processes (SOD2) and calcium pathways (S100A9 and S100A12). PMA/ionomycin stimulation induced a stronger up-regulation of T cell activation than B cell activation with dominance toward a Th1 response, including IL2, CD69 and TNFRSF9 genes. In addition, a very intense repression of THBS1 was observed, suggesting a predominant role of this matricellular glycoprotein during T/B cell stimulation by tumor inducers. Repression of MHC class I genes was observed after PMA/ionomycin stimulation despite an up-regulation of the gene cascade involved in peptide processing and repression of MHC class II genes was observed after both stimulations. A significant reduction of antigen presentation to T cells was shared by the two types of responses that is likely to be due to separate mechanisms that need further elucidation. In addition, our results provided preliminary data suggesting a role of antisense transcripts mapping to the SLA complex during immune response. Conclusion: The SLA-RI/NRSP8-13K was highly relevant to. On the one hand the SLA-RI/NRSP8-13K was shown to be relevant and accurate to decipher two distinct innate immune responses by PBMCs indicating that this chip will constitute a valuable tool to further study immunity and resistance to disease in pig. On the other hand, the transcriptom analysis revealed specific and common features of the innate immune response according to stimulation that increase knowledge on pig immunity. Keywords: immune response activation in pig PBMCs Two-condition experiment, LPS stimulated PBMCs vs. mock-stimulated PBMCs, PMA_ionomycine stimulated PBMCs vs.mock-stimulated PBMCs. Biological replicates: 1 control, 1 LPS stimulated and 1 PMA_ionomycine stimulated from 7 animals independently grown and harvested. Dye-swap design. One replicate per array. 28 slides.