Introduction: The use of ECMO in critically ill children with severe cardiopulmonary failure is associated with increased risk of acute brain injury (ABI) and mortality. The role of the epigenome in neuroinflammatory pathways remains unexplored. Methods: We analyzed differences in methylation signatures from peripheral blood mononuclear cells across 38 pediatric patients enrolled in the BEAM study, a multicenter, prospective, observational study in children supported on ECMO. Methylation sequencing was performed with the Infinium EPICv2 microarray. Patients were stratified into two cohorts: pediatric patients with (n=18) vs without (n=20) ABI on ECMO. Individuals were matched based on age (< 1 year of age) and ECMO indication. We analyzed differentially methylated probes (DMPs) and gene-set enrichment (GSEA) between children on ECMO with and without ABI and corrected for multiple testing with false discovery rate < 0.05. Results: The final study included methylation sequencing data of 867,448 probes across the 38 pediatric patient samples. Primary ECMO indication included cardiac (n=22), ECPR (n=12), and pulmonary (n=4). After correction for multiple testing, there were no significant methylation differences between the ECMO groups with vs without ABI, likely due to a small sample size and possible effect of the ECMO course overshadowing any methylation signatures from brain injury specifically. However, GSEA on the 100 most nominally significant DMPs showed perturbation of immune response pathways (p=0.02), implicating genes including VSTM1, NPLOC4, WRNIP1, NR4A3, ZBP1, VAMP8. Of note, 7 nominally significant probes mapped to recognized transcription start site (TSS) regions and 5UTR/Exon 1 of VSTM1 and 6 to ZBP1, immune regulatory genes highly expressed in whole blood. Lower levels of methylation were universally found across these probes in the ECMO group with ABI compared to no ABI, suggesting an upregulation of an inflammatory process. We were not able to identify any specific signatures indicative of neuroinflammation. Conclusions: ECMO support involves an altered inflammatory response that corresponds to changes in the epigenome. Methylation biomarkers of inflammation in these patients provide insight into the underlying biological pathways and risk-stratification for children requiring ECMO.
Xian et al. (Sun,) studied this question.