(C33) Association of MicroRNAs with Sudden Death in Boxer Dogs with Arrhythmogenic Right Ventricular Cardiomyopathy

Abstract: Background – Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a common condition in Boxer dogs associated with sudden death. Clinical diagnosis relies on the detection of ventricular arrhythmias but does not predict disease severity. Circulating microRNAs have been identified as predictive factors of recurrent arrhythmias in people, but studies in dogs are still lacking.

Hypothesis – MicroRNAs are differentially expressed (DE) in Boxers that manifested sudden death compared to those that died from other causes.

Animals – Cardiac samples from Boxer dogs that experienced sudden death due to ARVC (SCD; n=4), non-cardiac-related death (NCD; n=4), and healthy mixed-breed dogs (CTRL; n=4).

Methods – Cross-sectional study. Total RNA was extracted using a commercial kit and subjected to small RNA sequencing and qPCR validation. Fold regulation>1.5 in either direction and p< 0.05 were considered for all comparisons.

Results – A total of 88 miRNAs with the highest fold changes between groups were selected for validation using customized qPCR panels. Upon validation, in SCD vs CTRL, 13 miRNAs were DE, while nine were DE in NCD vs CTRL. On qPCR, miR-885 and miR-31 were downregulated in SCD vs NCD, though in sequencing only miR-208a was downregulated. Pathways regulated by the DE miRNAs include the MAPK, FoxO, TNF, and PI3K-Akt.

Conclusions and Clinical Importance – MicroRNAs may help stratify Boxers with a higher risk of sudden death. Some of the pathways linked to these microRNAs have been described in human ARVC and may provide insights into the pathophysiology and assist in developing new targeted therapies.