Neonatal cerebral vascular injury by prolonged asphyxia - Neonatal asphyxia is a leading cause of neurodevelopmental morbidities. Hypothermia, the only therapeutic option indicated for infants with moderate-to-severe asphyxia/hypoxia, does not provide full neurological recovery. Clearly, seeking new therapeutic interventions to prevent asphyxia-induced complications is crucial. This proposal is focused on cerebral vascular component of asphyxia in neonates. Cerebral vascular dysfunction and blood-brain barrier (BBB) disruption are important components of neonatal brain injury. Endothelial cells and astrocytes, the intrinsic components of the neurovascular unit, are adversely affected by prolonged asphyxia. Brain oxidative stress due to glutamate excitotoxicity and inflammation is the major factor in the pathophysiology of neonatal encephalopathy. This project searches for novel mechanisms that preserve the functional integrity of the neurovascular unit during prolonged asphyxia in neonates. Preliminary data show that Nox4 NADPH oxidase is the major source of reactive oxygen species in cerebral endothelium during neonatal asphyxia. Alternatively, H2S is a gasotransmitter with antioxidant properties enzymatically produced by astrocytes. We propose the central hypothesis that novel neurovascular cell-directed therapy that combines selectively blocking Nox4 NADPH oxidase activation with enhancing H2S-based antioxidant defense mechanism prevents cerebrovascular disease caused by neonatal asphyxia. We will use live newborn pigs, brain tissue, freshly isolated cortical cerebral vessels and astrocytes, and primary cultures of cerebral endothelial cells and cortical astrocytes to test three specific hypotheses: 1. Blocking Nox4 NADPH oxidase activity prevents endothelial dysfunction caused by asphyxia. 2. Enhancing H2S-based endogenous antioxidant mechanism prevents astrocyte dysfunctions caused by asphyxia. 3. Combination neurovascular-targeted therapy using Nox4-targeting antioxidants and H2S-elevating agents supplemented by therapeutic hypothermia as a standard care prevents cerebrovascular disease caused by prolonged neonatal asphyxia. We will use an exceptional combination of complementary techniques in a translational large animal model of neonatal cerebrovascular physiology and disease. Our research is unique, as it combines functional and mechanistic studies in intact cerebral circulation with investigation of the cellular and molecular mechanisms involved in pathophysiology of cerebrovascular disease. Preventing neonatal cerebral vascular disease translates into prevention of neonatal encephalopathy and improving health of a new generation. This project may lead to the development of novel translationally relevant neurovascular-targeting treatments to fully protect the neonatal brain during asphyxia. Importantly, we collected sufficient preliminary data to support our hypothesis on neurovascular cell-directed combination therapy for neonatal cerebral vascular disease.
