Vitamin D insufficiency in neonatal hypoxic-ischemic encephalopathy.

BACKGROUND: Vitamin D has neuroprotective and immunomodulatory properties, and deficiency is associated with worse stroke outcomes. Little is known about effects of hypoxia-ischemia or hypothermia treatment on vitamin D status in neonates with hypoxic-ischemic encephalopathy (HIE). We hypothesized vitamin D metabolism would be dysregulated in neonatal HIE altering specific cytokines involved in Th17 activation, which might be mitigated by hypothermia. METHODS: We analyzed short-term relationships between 25(OH) and 1,25(OH)2 vitamin D, vitamin D binding protein, and cytokines related to Th17 function in serum samples from a multicenter randomized controlled trial of hypothermia 33 °C for 48 h after HIE birth vs. normothermia in 50 infants with moderate to severe HIE. RESULTS: Insufficiency of 25(OH) vitamin D was observed after birth in 70% of infants, with further decline over the first 72 h, regardless of treatment. 25(OH) vitamin D positively correlated with anti-inflammatory cytokine IL-17E in all HIE infants. However, Th17 cytokine suppressor IL-27 was significantly increased by hypothermia, negating the IL-27 correlation with vitamin D observed in normothermic HIE infants. CONCLUSION: Serum 25(OH) vitamin D insufficiency is present in the majority of term HIE neonates and is related to lower circulating anti-inflammatory IL-17E. Hypothermia does not mitigate vitamin D deficiency in HIE.

Altered circulating leukocytes and their chemokines in a clinical trial of therapeutic hypothermia for neonatal hypoxic ischemic encephalopathy*.

OBJECTIVES: To determine systemic hypothermia's effect on circulating immune cells and their corresponding chemokines after hypoxic ischemic encephalopathy in neonates. DESIGN: In our randomized, controlled, multicenter trial of systemic hypothermia in neonatal hypoxic ischemic encephalopathy, we measured total and leukocyte subset and serum chemokine levels over time in both hypothermia and normothermia groups, as primary outcomes for safety. SETTING: Neonatal ICUs participating in a Neurological Disorders and Stroke sponsored clinical trial of therapeutic hypothermia. PATIENTS: Sixty-five neonates with moderate to severe hypoxic ischemic encephalopathy within 6 hours after birth. INTERVENTIONS: Patients were randomized to normothermia of 37°C or systemic hypothermia of 33°C for 48 hours. MEASUREMENTS AND MAIN RESULTS: Complete and differential leukocyte counts and serum chemokines were measured every 12 hours for 72 hours. The hypothermia group had significantly lower median circulating total WBC and leukocyte subclasses than the normothermia group before rewarming, with a nadir at 36 hours. Only the absolute neutrophil count rebounded after rewarming in the hypothermia group. Chemokines, monocyte chemotactic protein-1 and interleukin-8, which mediate leukocyte chemotaxis as well as bone marrow suppression, were negatively correlated with their target leukocytes in the hypothermia group, suggesting active chemokine and leukocyte modulation by hypothermia. Relative leukopenia at 60-72 hours correlated with an adverse outcome in the hypothermia group. CONCLUSIONS: Our data are consistent with chemokine-associated systemic immunosuppression with hypothermia treatment. In hypothermic neonates, persistence of lower leukocyte counts after rewarming is observed in infants with more severe CNS injury.