Therapeutic Modalities Targeting Neuroinflammation After Neonatal Hypoxia-Ischemia

Hypoxia-ischemia (HI) occurs in 1-6/1000 live full-term births (Shankaran, 2009). Of those affected, 15-20% will die in the postnatal period, and 25% of survivors will be left with long-term neurological disabilities (Gunn, 2000; Vannucci, 1997; Fatemi, 2009). It has become increasingly clear that peripheral immune cells infiltrate the brain parenchyma as part of the physiological response to tissue damage after HI injury. The interplay between infiltrating immune cells and brain resident cells during the inflammatory response is however dynamic and complex; in that neuro-immune crosstalk, by way of specific molecular mediators, is responsible for both neurodestructive as well as neuroprotective outcomes. Herein, we tested the hypothesis that COX-2 mediates mechanisms of brain injury and that G-CSF exerts structural and functional protection after neonatal HI. To mimic the clinical features of HI brain injury, neonatal rat pups were subjected to unilateral carotid artery ligation followed by 2 hours of hypoxia (8% O2 at 37°C). We used a gain and loss of function approach (pharmacological activation or inhibition, respectively) for COX-2, a neutralizing antibody for lL-15, and a gene silencer for natural killer cells in both splenectomized and non-splenectomized rats to verify the role of COX-2 in splenic immune cell responses following HI. We found that elevations in COX-2 expression by immune cells promoted IL-15 expression in astrocytes and infiltration of inflammatory cells; additionally, down-regulated the pro-survival protein, PI3K, resulting in caspase-3 mediated neuronal death. Additionally, we investigated the efficacy of G-CSF on long-term Hl-induced morphological and functional outcomes using two different dosing regimens; and found the neurotrophic factor to significantly improve behavioral and neuropathological recovery. These results provide insight into the mechanistic basis of mflammation and indentify key components of the neuroinflammatory response after HI. Thus, we propose that COX-2 inhibition or G-CSF administration during the acute phase of injury are novel therapeutic modalities that target detrimental and beneficial mechanisms of neuroinflammation, respectively, and may offer a safe and effective option with longterm benefits for the Hl-injured infant

Isoflurane posttreatment reduces brain injury after an intracerebral hemorrhagic stroke in mice

BACKGROUND: Intracerebral hemorrhage (ICH) is a devastating stroke subtype affecting 120,000 Americans annually. Of those affected, 40%to 50% will die within the first 30 days, whereas the survivors are left with a lifetime of neurobehavioral disabilities. Recently, it has been shown that volatile anesthetics such as isoflurane can reduce brain injury after an ischemic stroke. As a result, in this study, we investigated the effects of isoflurane as a posttreatment therapeutic modality in ICH-injured mice. Specifically, we investigated whether isoflurane posttreatment can preserve the structural integrity of the brain by reducing apoptotic damage and, in turn, improve functional outcome by amelioration of brain edema and neurobehavioral deficits. METHODS: Male CD1 mice (n = 53) were divided into the following groups: sham (n = 14), ICH (n = 14), ICH treated with 1.5% isoflurane posttreatment for 1 hour (n = 15), and ICH treated with 1.5% isoflurane posttreatment for 2 hours (n = 10). The blood injection ICH model was adapted; this involved extracting autologous blood from the mouse tail and injecting it directly into the right basal ganglia. One hour after surgery, treated mice were placed in a glass chamber maintained at 37°C and infused with 1.5% isoflurane for 1 or 2 hours. At 24 hours postinjury, mice were assessed for neurobehavioral deficits using the Modified Garcia Score and then killed and assessed for brain water content. Double immunofluorescent staining was performed using neuronal marker MAP-2 and TUNEL under a fluorescent microscope to assess for apoptosis. RESULTS: Our results indicated that after 1-hour 1.5% isoflurane posttreatment, there was a significant reduction in brain edema, a decrease in apoptotic cell death, and a significant improvement in neurobehavioral deficits. CONCLUSIONS: Our results suggest that isoflurane may be an effective posttreatment therapeutic option for ICH because of its ability to reduce structural damage and subsequently preserve functional integrity