Differential DNA methylation by early versus late parenteral nutrition in the PICU: a biological basis for its impact on emotional and behavioral problems documented 4 years later

Background: The PEPaNIC multicenter randomized controlled trial (RCT) has shown that early administration of supplemental parenteral nutrition (early-PN) as compared with withholding PN for 1 week (late-PN) induced long-term internalizing, externalizing and total emotional/behavioral problems in critically ill children, as observed 4 years later. Early-PN was further shown to alter the methylation status of 37 CpG-sites in leukocyte DNA between admission and discharge from the pediatric intensive care unit (PICU). In a preplanned subanalysis of the PEPaNIC trial, we now investigated whether the altered methylation of these CpG-sites could statistically explain the negative impact of early-PN on emotion/behavior documented 4 years after PICU admission. Results: The combination of DNA methylation data and data on behavior 4 years after PICU admission was available for 403 of the 1440 patients (aged 0–17 years at PICU admission) who were included in the PEPaNIC RCT (192 early-PN and 211 late-PN patients). Mediation analyses with use of bootstrapped multivariable non-linear regression analyses adjusted for baseline risk factors revealed that the adverse alterations by early-PN in methylation of the 37 CpG-sites together statistically explained its harmful impact on internalizing, externalizing and total emotional/behavioral problems. When adding the methylation status of the 37 CpG-sites to the models, the explanatory power improved with a 1.710 to 1.851-fold increase, and the impact of the altered methylation status of the CpG-sites explained the impact of the randomization to early-PN versus late-PN. Conclusions: Abnormal DNA methylation induced by the early use of PN in the PICU provides a biological basis for its long-term harmful effect on emotion/behavior of critically ill children 4 years after PICU admission. Trial Registration ClinicalTrials.gov NCT01536275, registered February 17, 2012, https://clinicaltrials.gov/ct2/show/NCT01536275