Abstract 10: Transcriptional Profiling of the Neuroprotective Mechanisms of Inhaled Nitric Oxide in a Swine Model of Pediatric Cardiac Arrest
Introduction: Neurologic morbidity is common after pediatric cardiac arrest and inhaled nitric oxide (iNO) may be protective. RNA sequencing may have a role in identifying differences in gene expression related to neurologic injury following cardiac arrest and the neuroprotective mechanism of iNO. Hypothesis: We hypothesized that genes related to energetically intensive functions such as synaptic vesicle trafficking would be downregulated after cardiac arrest and that this finding would be less prominent with iNO therapy. Methods: One-month old piglets underwent sham anesthesia or 7 minutes of asphyxia, induction of VF, and randomized and blinded therapy with AHA guideline-based CPR with iNO (iNO + ) or without iNO (iNO - ). Four hours post-ROSC, animals were euthanized and RNA was extracted from cerebral cortical tissue and sequenced on an Illumina HiSeq instrument. STAR was used to align reads to the SusScrofa11.1 reference followed by quantification with sub-reads. Normalization and differential expression analyses were performed using DESeq2 with RIN, RNA concentration, shocks delivered, epinephrine doses, post-ROSC epinephrine use, cerebral blood flow, ETCO 2 , and blood gas values as covariates. Benjamini-Hochberg-adjusted p values <0.05 were considered statistically significant. Results: Sham animals (n=5) and cardiac arrest animals with ROSC (iNO+ n=9; iNO- n=6) were included in analyses. 817 genes were differentially expressed between cardiac arrest and sham. 798 genes were differentially expressed between iNO + and iNO - . 24 genes were differentially expressed in opposite directions in the two comparisons, making them candidates for protective mechanisms of iNO. These included genes related to synaptic vesicle function (RAB27B, PACSIN1, DOC2A) and maintenance of synaptic structure (SH2D5, CA10). Cardiac arrest induced downregulation of synaptic vesicle genes including SNAP25 and synaptophysin, while iNO induced upregulation of others in the same ontology, including synapsins and synaptogamins. Conclusions: Piglets subjected to asphyxial cardiac arrest exhibited downregulation of genes related to synaptic vesicle trafficking. This was partially prevented by treatment with iNO.