279 - Responses to Ibuprofen after Neonatal Hypoxic-Ischemic Brain Injury Vary by Genetic Background.

Publication Number: 4275.279

Valeria Zapata, Johns Hopkins University, Baltimore, MD, United States; Jacqueline Lewis, Johns Hopkins University, Baltimore, MD, United States; Adriana S. Hernandez, Johns Hopkins, Baltimore, MD, United States; Aeryn Sanner, Johns Hopkins University Department of Biology, Columbia, MD, United States; Michael Q. Nugent, Johns Hopkins University School of Medicine, Elkridge, MD, United States; Raul Chavez-Valdez, Johns Hopkins University School of Medicine, Baltimore, MD, United States

Background: Ibuprofen (IBU) attenuates inflammation, decreasing cytokine expression, and shifting ApoE distribution to improve dendritic development in ApoE4 carriers. We have recently reported that ApoE4 mice have greater hippocampal inflammation in response to neonatal hypoxic-ischemic (HI) brain injury.

Objective: Since IBU provides neuroprotection in other animal models of brain injury, we objective is to test if IBU would attenuate inflammation after neonatal HI in ApoE4 carriers.

Design/Methods: Cerebral HI injury was induced in C57BL6 (wt) and ApoE4 humanized mice at P10, via unilateral common carotid artery ligation followed by hypoxia (FiO2 0.08 x 45 min) with anesthesia exposed littermates as shams. Pups were randomized starting at 4h post HI to placebo (NS, PLA) or IBU (10mg/k/day x 3 or 10 doses). Serums and hippocampi were analyzed for IL-1β and IL-10 (MSD), additionally hippocampi were also analyzed for α-fodrin and GFAP (western blot) and free radical injury (3-nitrotyrosine, 3NT) at P13 and P25.

Results: Three doses of IBU lowered the pro-inflammatory IL-1β in serum 72h after neonatal HI, without altering the anti-inflammatory IL-10 in both wt and ApoE4 pups (A). While 3 doses of IBU also attenuated hippocampal IL-1β levels (B) and apoptosis (α-fodrin breakdown) in the wt hippocampus, this did not attenuated astrocytosis (GFAP) and free radical damage (3NT) (C1). Unlike the effect in the wt hippocampi, a 3-dose IBU course increased IL-1β levels (vs. Sham and vs. HI/PLA) in ApoE4 hippocampi (B) without changing apoptosis, astrocytosis and 3NT (C1). However, extending to a 10-dose IBU course resulted in greater apoptosis, astrocytosis and free radical damage in the ApoE4 hippocampi (vs. Sham and HI/ PLA)(C2).

Conclusion(s): A 3-dose IBU course produces paradoxical responses in ApoE4 compared to wt after neonatal HI, worsening hippocampal inflammation only in ApoE4 despite systemic anti-inflammatory effects. Extending the course of IBU to 10 doses worsens the outcomes in the ApoE4 hippocampus. These results bring to our attention the importance of the genetic background when stratifying treatments for HI.

Paradoxical response to ibuprofen in the HI-injured ApoE4 hippocampi
(A) Serum levels of IL-1β showed a systemic antiinflammatory response of IBU in both wt and ApoE4. (B) While wt hippocampi showed the expected anti-inflammatory effect of IBU after HI, ApoE4 hippocampi showed the opposite. (C1) In wt, IBU decreases apoptosis although had no effects in GFAP and 3NT.(C2) Extended IBU course lead to late apoptosis, astrocytosis and free radical injury.