Time course of altered DNA methylation evoked by critical illness and by early administration of parenteral nutrition in the paediatric ICU

Background: A genome-wide study identifed de novo DNA methylation alterations in leukocytes of children at paediatric intensive care unit (PICU) discharge, ofering a biological basis for their impaired long-term development. Early parenteral nutrition (early-PN) in PICU, compared with omitting PN in the frst week (late-PN), explained diferential methylation of 23% of the afected CpG-sites. We documented the time course of altered DNA methylation in PICU and the impact hereon of early nutritional management. Results: We selected 36 early-PN and 36 late-PN matched patients, and 42 matched healthy children. We quantifed DNA methylation on days 3, 5 and 7 for the 147 CpG-sites of which methylation was normal upon PICU admission in this subset and altered by critical illness at PICU discharge. Methylation in patients difered from healthy children for 64.6% of the 147 CpG-sites on day 3, for 72.8% on day 5 and for 90.5% on day 7 as revealed by ANOVA at each time point. Within-patients methylation time course analyses for each CpG-site identifed diferent patterns based on paired t test p value and direction of change. Rapid demethylation from admission to day 3 occurred for 76.2% of the CpG-sites, of which 67.9% remained equally demethylated or partially remethylated and 32.1% further demethylated beyond day 3. From admission to day 3, 19.7% of the CpG-sites became hypermethylated, of which, beyond day 3, 34.5% remained equally hypermethylated or partially demethylated again and 65.5% further hypermethylated. For 4.1% of the CpG-sites, changes only appeared beyond day 3. Finally, for the CpG-sites afected by early-PN on the last PICU day, earlier changes in DNA methylation were compared for early-PN and late-PN patients, revealing that 38.9% were already diferentially methylated by day 3, another 25.0% by day 5 and another 13.9% by day 7. Conclusions: Critical illness- and early-PN-induced changes in DNA methylation occurred mainly within 3 days. Most abnormalities were at least partially maintained or got worse with longer time in PICU. Interventions targeting aberrant DNA methylation changes should be initiated earl

Leukocyte telomere length in paediatric critical illness

__Background:__ Children who have suffered from critical illnesses that required treatment in a paediatric intensive care unit (PICU) have long-term physical and neurodevelopmental impairments. The mechanisms underlying this legacy remain largely unknown. In patients suffering from chronic diseases hallmarked by inflammation and oxidative stress, poor long-term outcome has been associated with shorter telomeres. Shortened telomeres have also been reported to result from excessive food consumption and/or unhealthy nutrition. We investigated whether critically ill children admitted to the PICU have shorter-than-normal telomeres, and whether early parenteral nutrition (PN) independently affects telomere length when adjusting for known determinants of telomere length. __Methods:__ Telomere length was quantified in leukocyte DNA from 342 healthy children and from 1148 patients who had been enrolled in the multicenter, randomised controlled trial (RCT), PEPaNIC. These patients were randomly allocated to initiation of PN within 24 h (early PN) or to withholding PN for one week in PICU (late PN). The impact of early PN versus late PN on the change in telomere length from the first to last PICU-day was investigated with multivariable linear regression analyses. __Results:__ Leukocyte telomeres were 6% shorter than normal upon PICU admission (median 1.625 (IQR 1.446-1.825) telomere/single-copy-gene ratio (T/S) units vs. 1.727 (1.547-1.915) T/S-units in healthy children (P < 0.0001)). Adjusted for potential baseline determinants and leukocyte composition, early PN was associated with telomere shortening during PICU stay as compared with late PN (estimate early versus late PN -0.021 T/S-units, 95% CI -0.038; 0.004, P = 0.01). Other independent determinants of telomere length identified in this model were age, gender, baseline telomere length and fraction of neutrophils in the sample from which the DNA was extracted. Telomere shortening with early PN was independent of post-randomisation factors affected by early PN, including longer length of PICU stay, larger amounts of insulin and higher risk of infection. __Conclusions:__ Shorter than normal leukocyte telomeres are present in critically ill children admitted to the PICU. Early initiation of PN further shortened telomeres, an effect that was independent of other determinants. Whether such telomere-shortening predisposes to long-term consequences of paediatric critical illness should be further investigated in a prospective follow-up study

Dynamics and prognostic value of the hypothalamus–pituitary–adrenal axis responses to pediatric critical illness and association with corticosteroid treatment: a prospective observational study

Purpose: Increased systemic cortisol availability during adult critical illness is determined by reduced binding-proteins and suppressed breakdown rather than elevated ACTH. Dynamics, drivers and prognostic value of hypercortisolism during pediatric critical illness remain scarcely investigated. Methods: This preplanned secondary analysis of the PEPaNIC-RCT (N = 1440), after excluding 420 children treated with corticosteroids before PICU-admission, documented (a) plasma ACTH, (free)cortisol and cortisol-metabolism at PICU-admission, day-3 and last PICU-day, their prognostic value, and impact of withholding early parenteral nutrition (PN), (b) the association between corticosteroid-treatment and these hormones, and (c) the association between corticosteroid-treatment and outcome. Results: ACTH was normal upon PICU-admission and low thereafte

Impact of hyperglycemia on neuropathological alterations during critical illness

Context: Although preventing excessive hyperglycemia during critical illness may provide clinical neuroprotection, it remains debated whether normoglycemia is without risk for the brain. Objective: To address this question, we compared the neuropathological alterations in microglia, astrocytes, and neurons, with uncontrolled hyperglycemia, moderately controlled hyperglycemia, and normoglycemia during human critical illness. We further investigated the time course in an animal model. Design and Setting: We analyzed brain specimens from patients who died in the intensive care unit and from critically ill rabbits randomized to hyper- or normoglycemia. Patients/Other Participants: We compared 10 critically ill patients randomized to normoglycemia (104 ±9 mg/dl) or moderate hyperglycemia (173 ±32 mg/dl), and five patients with uncontrolled hyperglycemia (254 ±83 mg/dl) with 16 controls (out of hospital sudden deaths). Critically ill rabbits were randomized to hyperglycemia (315 ±32 mg/dl) or normoglycemia (85 ±13 mg/dl) and studied after 3 and 7 d. Interventions: Insulin was infused to control blood glucose. Main Outcome Measures and Results: Patients with uncontrolled hyperglycemia showed 3.7- 6- fold increased microglial activation, 54-95% reduced number and activation of astrocytes, more than 9-fold increased neuronal and glial apoptosis, and a 1.5-2-fold increase in damaged neurons in hippocampus and frontal cortex (all P≤0.05). Most of these abnormalities were attenuated with moderate hyperglycemia and virtually absent with normoglycemia. Frontal cortex of hyperglycemic rabbits that had been critically ill for 3 d only revealed microglial activation, followed after 7 d by astrocyte and neuronal abnormalities similar to those observed in patients, all prevented by normoglycemia. Conclusions: Preventing hyperg