Abstract 14028: N-formyl Peptide Receptor 2 Activation via Annexin A1 Up-Regulates Hematoma Resolution After Germinal Matrix Hemorrhage

Abstract

Introduction: Germinal matrix hemorrhage (GMH) is one of the leading causes of morbidity and mortality in preterm infants in the United States with little progress made in its clinical management. Survivors are often afflicted with long-term neurological sequelae, which include cerebral palsy, mental retardation, and post-hemorrhagic hydrocephalus. Blood clots disrupting normal cerebrospinal fluid circulation and absorption after germinal matrix hemorrhage are key contributors towards post-hemorrhagic hydrocephalus development. n-formyl peptide receptor 2 (FPR2), a G-protein-coupled receptor, has been associated with the activation of scavenger receptor CD36. CD36, a transmembrane glycoprotein, plays an essential role in microglia phagocytic blood clot clearance after GMH. Currently, FPR2’s role in blood clot clearance after hemorrhagic stroke is unknown. Hypothesis: We hypothesize that FPR2 activation by Annexin A1 will enhance hematoma resolution via upregulation of the CD36 signaling pathway, thereby improving short- and long-term neurological outcomes. Methods: Bacterial collagenase (0.3 U) was infused intraparenchymally into the right hemispheric ganglionic eminence in male and female P7 rat pups to induce GMH. Annexin A1 and FPR2 Inhibitor (Boc2) were given at 1-hour post-GMH via intranasal administration. Short-term neurobehavior were assessed using negative geotaxis test. Hematoma volume was assessed using hemoglobin assay. Protein expression was assessed using western blots. Long-term neurocognitive deficits and motor coordination were assessed using Morris water maze, rotarod, and foot fault tests. Nissl staining was conducted on long-term samples to calculate ventricular dilation. Results: We have demonstrated that Annexin A1 treatment decreased hemoglobin content and improved neurobehavior at 72 hours post-ictus. Annexin A1 attenuated post-hemorrhagic hydrocephalus and neurological deficits 4 weeks post-ictus. Lastly, treatment increased FPR2 and CD36 protein expression. Conclusions: This present study demonstrates that FPR2 agonism via Annexin A1 enhances blood clot clearance, thereby improving outcomes after GMH.