Lung-Specific Extracellular Superoxide Dismutase Improves Cognition of Adult Mice Exposed to Neonatal Hyperoxia

Lung and brain development is often altered in infants born preterm and exposed to excess oxygen, and this can lead to impaired lung function and neurocognitive abilities later in life. Oxygen-derived reactive oxygen species and the ensuing inflammatory response are believed to be an underlying cause of disease because over-expression of some anti-oxidant enzymes is protective in animal models. For example, neurodevelopment is preserved in mice that ubiquitously express human extracellular superoxide dismutase (EC-SOD) under control of an actin promoter. Similarly, oxygen-dependent changes in lung development are attenuated in transgenic SftpcEC−SOD mice that over-express EC-SOD in pulmonary alveolar epithelial type II cells. But whether anti-oxidants targeted to the lung provide protection to other organs, such as the brain is not known. Here, we use transgenic SftpcEC−SOD mice to investigate whether lung-specific expression of EC-SOD also preserves neurodevelopment following exposure to neonatal hyperoxia. Wild type and SftpcEC−SOD transgenic mice were exposed to room air or 100% oxygen between postnatal days 0–4. At 8 weeks of age, we investigated neurocognitive function as defined by novel object recognition, pathologic changes in hippocampal neurons, and microglial cell activation. Neonatal hyperoxia impaired novel object recognition memory in adult female but not male mice. Behavioral deficits were associated with microglial activation, CA1 neuron nuclear contraction, and fiber sprouting within the hilus of the dentate gyrus (DG). Over-expression of EC-SOD in the lung preserved novel object recognition and reduced the observed changes in neuronal nuclear size and myelin basic protein fiber density. It had no effect on the extent of microglial activation in the hippocampus. These findings demonstrate pulmonary expression of EC-SOD preserves short-term memory in adult female mice exposed to neonatal hyperoxia, thus suggesting anti-oxidants designed to alleviate oxygen-induced lung disease such as in preterm infants may also be neuroprotective

Resolving the homology-function relationship through comparative genomics of membrane-trafficking machinery and parasite cell biology

With advances in DNA sequencing technology, it is increasingly common and tractable to informatically look for genes of interest in the genomic databases of parasitic organisms and infer cellular states. Assignment of a putative gene function based on homology to functionally characterized genes in other organisms, though powerful, relies on the implicit assumption of functional homology, i.e. that orthology indicates conserved function. Eukaryotes reveal a dazzling array of cellular features and structural organization, suggesting a concomitant diversity in their underlying molecular machinery. Significantly, examples of novel functions for pre-existing or new paralogues are not uncommon. Do these examples undermine the basic assumption of functional homology, especially in parasitic protists, which are often highly derived? Here we examine the extent to which functional homology exists between organisms spanning the eukaryotic lineage. By comparing membrane trafficking proteins between parasitic protists and traditional model organisms, where direct functional evidence is available, we find that function is indeed largely conserved between orthologues, albeit with significant adaptation arising from the unique biological features within each lineage

Neonatal Hyperoxia as a Model to Investigate Long-Term Sequelae Associated with Preterm Birth

Thesis (Ph.D.)--University of Rochester. School of Medicine & Dentistry. Dept. of Environmental Medicine, 2013.There is growing appreciation that environmental exposures during developmentally vulnerable periods of growth and maturation can influence the onset of many childhood and adult diseases. For example, individuals born preterm and exposed to excess levels of oxygen (hyperoxia) often exhibit reduced lung function, are frequently re-hospitalized following respiratory viral infections, and are at increased risk for neurodevelopmental impairment later in life. Similarly, adult mice exposed to hyperoxia during postnatal days 0-4 exhibit permanent changes in lung development, are more sensitive to influenza virus infection, and have an impaired ability to learn when compared to siblings birthed into room air. However, the dose of neonatal oxygen required to increase viral sensitivity remained unclear, and the pathways through which hyperoxia exerts these long-term changes are not completely understood. Therefore, the objectives of this thesis were to determine the dose of neonatal oxygen sufficient to disrupt the host response to viral infection in adult mice, and to investigate potential pathways through which early-life exposure to oxygen alters viral sensitivity and impairs neurodevelopment later in life. The results presented here demonstrate that exposure to more than 80% oxygen (FiO2) at birth is required to increase inflammation and promote fibrotic lung disease following infection in adult mice. Subsequent studies revealed that overexpression of the antioxidant extracellular superoxide dismutase (EC-SOD) in the respiratory epithelium prevents hyperoxia-induced fibrotic lung disease following infection, but not the excessive recruitment of leukocytes, which was attributed to monocyte chemoattractant protein (MCP)-1 gene expression. Lastly, it was determined that EC-SOD targeted to the lungs of mice protects against hyperoxia-mediated changes in the alveolar epithelium, and that this protection is associated with a preservation of the cognitive ability to learn. Taken together, these findings establish that lung development and the host response to influenza virus are altered by different doses of neonatal oxygen, and that neonatal hyperoxia alters the host response to influenza virus and impairs neurodevelopment through unique pathways. Ultimately, these studies support the use of neonatal hyperoxia as a model for continued investigation of long-term pulmonary and neurodevelopmental sequelae associated with preterm birth and earlylife exposure to oxygen

Spinal 12-lipoxygenase-derived hepoxilin A3 contributes to inflammatory hyperalgesia via activation of TRPV1 and TRPA1 receptors.

Peripheral inflammation initiates changes in spinal nociceptive processing leading to hyperalgesia. Previously, we demonstrated that among 102 lipid species detected by LC-MS/MS analysis in rat spinal cord, the most notable increases that occur after intraplantar carrageenan are metabolites of 12-lipoxygenases (12-LOX), particularly hepoxilins (HXA(3) and HXB(3)). Thus, we examined involvement of spinal LOX enzymes in inflammatory hyperalgesia. In the current work, we found that intrathecal (IT) delivery of the LOX inhibitor nordihydroguaiaretic acid prevented the carrageenan-evoked increase in spinal HXB(3) at doses that attenuated the associated hyperalgesia. Furthermore, IT delivery of inhibitors targeting 12-LOX (CDC, Baicalein), but not 5-LOX (Zileuton) dose-dependently attenuated tactile allodynia. Similarly, IT delivery of 12-LOX metabolites of arachidonic acid 12(S)-HpETE, 12(S)-HETE, HXA(3), or HXB(3) evoked profound, persistent tactile allodynia, but 12(S)-HpETE and HXA(3) produced relatively modest, transient heat hyperalgesia. The pronociceptive effect of HXA(3) correlated with enhanced release of Substance P from primary sensory afferents. Importantly, HXA(3) triggered sustained mobilization of calcium in cells stably overexpressing TRPV1 or TRPA1 receptors and in acutely dissociated rodent sensory neurons. Constitutive deletion or antagonists of TRPV1 (AMG9810) or TRPA1 (HC030031) attenuated this action. Furthermore, pretreatment with antihyperalgesic doses of AMG9810 or HC030031 reduced spinal HXA(3)-evoked allodynia. These data indicate that spinal HXA(3) is increased by peripheral inflammation and promotes initiation of facilitated nociceptive processing through direct activation of TRPV1 and TRPA1 at central terminals

Spinal 12-lipoxygenase-derived hepoxilin A3 contributes to inflammatory hyperalgesia via activation of TRPV1 and TRPA1 receptors.

Peripheral inflammation initiates changes in spinal nociceptive processing leading to hyperalgesia. Previously, we demonstrated that among 102 lipid species detected by LC-MS/MS analysis in rat spinal cord, the most notable increases that occur after intraplantar carrageenan are metabolites of 12-lipoxygenases (12-LOX), particularly hepoxilins (HXA(3) and HXB(3)). Thus, we examined involvement of spinal LOX enzymes in inflammatory hyperalgesia. In the current work, we found that intrathecal (IT) delivery of the LOX inhibitor nordihydroguaiaretic acid prevented the carrageenan-evoked increase in spinal HXB(3) at doses that attenuated the associated hyperalgesia. Furthermore, IT delivery of inhibitors targeting 12-LOX (CDC, Baicalein), but not 5-LOX (Zileuton) dose-dependently attenuated tactile allodynia. Similarly, IT delivery of 12-LOX metabolites of arachidonic acid 12(S)-HpETE, 12(S)-HETE, HXA(3), or HXB(3) evoked profound, persistent tactile allodynia, but 12(S)-HpETE and HXA(3) produced relatively modest, transient heat hyperalgesia. The pronociceptive effect of HXA(3) correlated with enhanced release of Substance P from primary sensory afferents. Importantly, HXA(3) triggered sustained mobilization of calcium in cells stably overexpressing TRPV1 or TRPA1 receptors and in acutely dissociated rodent sensory neurons. Constitutive deletion or antagonists of TRPV1 (AMG9810) or TRPA1 (HC030031) attenuated this action. Furthermore, pretreatment with antihyperalgesic doses of AMG9810 or HC030031 reduced spinal HXA(3)-evoked allodynia. These data indicate that spinal HXA(3) is increased by peripheral inflammation and promotes initiation of facilitated nociceptive processing through direct activation of TRPV1 and TRPA1 at central terminals