Evaluating the feasibility of using whole blood gene expression profiles to identify novel targets in canine septic peritonitis.

Objective: To assess gene expression profiles in canine whole blood with and without septic peritonitis to assess workflow feasibility and identify potential blood biomarkers that could be further investigated in future studies.

Methods: This study enrolled 6 dogs with cytologically confirmed septic peritonitis of any cause and 6 healthy dogs. All dogs had a CBC and biochemistry performed. The dogs with septic peritonitis also had point-of-care lactate and blood oxygen saturation measured for acute patient physiologic and laboratory evaluation score calculation. All dogs then had 2.5 mL of whole blood collected and placed into an RNA stabilization tube, which was processed using a commercial assay based on the hybridization of fluorescent probes for transcript quantification. Quality control, normalization, and data visualization were performed. Raw counts were exported, and differential expression was performed.

Results: The evaluation of canine whole blood expression profiles was confirmed to be feasible. Differential expression analysis of septic and nonseptic dogs demonstrated distinct gene expression profile signatures. Five genes of interest were upregulated in septic whole blood including matrix metallopeptidase 9, IL-1 receptor type 2, proliferating cell nuclear antigen, phosphatidylinositol 3-kinase catalytic-γ, and cluster of differentiation 55.

Conclusions: The study and associated workflow were feasible and can be scaled in confirmatory studies.

Clinical relevance: Future studies are now proposed to further validate the increased expression of putative biomarkers in a larger cohort of canine septic peritonitis patients with more relevant comparator control cohorts.