Transcriptomic analysis of peripheral blood from German Shepherd dogs with osteoarthritis for identification of diagnostic biomarkers

Abstract Canine forms of osteoarthritis (OA) are very similar to those in humans and represent a welfare problem in the dog world population. In this study, we investigated the transcriptomic profile of peripheral blood in German Shepherd dogs with OA in order to identify putative diagnosis biomarkers. The bulk RNA-seq experiment was performed in a cohort of 12 adult dogs, 5 OA-affected and 7 unaffected. Radiographs of the affected dogs revealed signs of progressive OA in hip, elbow and stifle joints. The expression analysis showed 171 differentially expressed genes (DEGs), 113 were upregulated and 58 were downregulated compared to control dogs P (< 0.01). This pool of genes was functional annotated for signaling pathways using PANTHER tools. No overrepresented pathways were found. To gain further insights of the functional role of the DEGs in OA, we set a threshold of log2FoldChange value between -1.5 and 1.5. We ended up with 24 top up- and downregulated transcripts. Prioritization of these DEGs according to their known functional knowledge, revealed five possible candidates for OA biomarkers. The downregulated OSCAR gene encodes the osteoclast associated Ig-like receptor, which is involved in osteoclastogenesis regulation and bone homeostasis. In addition, the upregulated microRNA MIR339-1 and ncRNAs: LOC106559235 (downregulated), LOC102156762 (downregulated) and LOC111096460 (upregulated) are regulatory sequences, stable for gene profiling assessment in blood and related to OA pathogenesis regulation. We suggest OSCAR as the more likely candidate biomarker for OA diagnosis in dogs and, provide evidence of new circulating regulatory sequences differentially expressed in canine OA.