Bacterial and Viral Products Affect Differential Pattern Recognition Receptor Activation of Chicken Thrombocytes Evidenced through RNA Sequencing.

It is now well understood that thrombocytes (nucleated platelets) express TLRs and respond to both bacterial and viral products. Release of proinflammatory molecules can be expected following relatively short exposure times to LPS, lipoteichoic acid (LTA), thymidine homopolymer phosphorothioate oligonucleotide [Poly(dT)], and polyinosinic-polycytidylic acid [Poly(I:C)]. This study reports the varied expressions of genes encoded for components of the TLR, nucleotide binding oligomerization domain-like receptor, and retinoic acid-inducible gene RIG-like receptor signaling pathways in response to the TLR ligands listed above. Highly sensitive RNA-sequencing technologies were used to analyze the complete transcriptome of thrombocytes treated with all four microbial products for a period of 1 h. A total of 14,326 gene transcripts were found in chicken thrombocytes across all ligand exposures. After 1 h of stimulation with ligands, 87, 138, 1013, and 22 genes were upregulated for LTA, LPS, Poly(dT), and Poly(I:C), and 12, 142, 249, and 16 genes were downregulated for LTA, LPS, Poly(dT), and Poly(I:C), respectively, with at least a 1-fold change relative to unexposed thrombocytes. Summarizations of biological processes, protein classes, and biochemical pathways reveal the role of chicken thrombocytes in proinflammatory responses linked to key signaling pathways. TLR, nucleotide binding oligomerization domain-like receptor, and retinoic acid-inducible gene RIG-like receptor pathways were mapped based on the transcriptome results with gene expression for common signal and proinflammatory mediators highlighted. The information reported in this study is useful for defining a limited set of proinflammatory molecules to evaluate in cases of either bacterial or viral disease monitoring.