Examinando por Autor "Herrera-Marschitz, Mario"
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Ítem Gold nanorods/siRNA complex administration for knockdown of PARP-1: A potential treatment for perinatal asphyxia(Dove Medical Press Ltd., 2018) Vio, Valentina; Riveros, Ana L.; Tapia-Bustos, Andrea; Lespay-Rebolledo, Carolyne; Pérez-Lobos, Ronald; Muñoz, Luis; Pismante, Paola; Morales, Paola; Araya, Eyleen; Hassan, Natalia; Herrera-Marschitz, Mario; Kogan, Marcelo J.Background: Perinatal asphyxia interferes with neonatal development, resulting in long-term deficits associated with systemic and neurological diseases. Despite the important role of poly (ADP-ribose) polymerase 1 (PARP-1) in the regulation of gene expression and DNA repair, overactivation of PARP-1 in asphyxia-exposed animals worsens the ATP-dependent energetic crisis. Inhibition of PARP-1 offers a therapeutic strategy for diminishing the effects of perinatal asphyxia. Methods: We designed a nanosystem that incorporates a specific siRNA for PARP-1 knockdown. The siRNA was complexed with gold nanorods (AuNR) conjugated to the peptide CLPFFD for brain targeting. Results: The siRNA was efficiently delivered into PC12 cells, resulting in gene silencing. The complex was administered intraperitoneally in vivo to asphyxia-exposed rat pups, and the ability of the AuNR-CLPFFD/siRNA complex to reach the brain was demonstrated. Conclusion: The combination of a nanosystem for delivery and a specific siRNA for gene silencing resulted in effective inhibition of PARP-1 in vivo. © 2018 Vio et al.Ítem Targeting Sentinel Proteins and Extrasynaptic Glutamate Receptors: a Therapeutic Strategy for Preventing the Effects Elicited by Perinatal Asphyxia?(Springer New York LLC, 2018-02) Herrera-Marschitz, Mario; Perez-Lobos, Ronald; Lespay-Rebolledo, Carolyne; Tapia-Bustos, Andrea; Casanova-Ortiz, Emmanuel; Morales, Paola; Valdés, José-Luis; Bustamante, Diego; Cassels, Bruce K.Perinatal asphyxia (PA) is a relevant cause of death at the time of labour, and when survival is stabilised, associated with short- and long-term developmental disabilities, requiring inordinate care by health systems and families. Its prevalence is high (1 to 10/1000 live births) worldwide. At present, there are few therapeutic options, apart from hypothermia, that regrettably provides only limited protection if applied shortly after the insult. PA implies a primary and a secondary insult. The primary insult relates to the lack of oxygen, and the secondary one to the oxidative stress triggered by re-oxygenation, formation of reactive oxygen (ROS) and reactive nitrogen (RNS) species, and overactivation of glutamate receptors and mitochondrial deficiencies. PA induces overactivation of a number of sentinel proteins, including hypoxia-induced factor-1α (HIF-1α) and the genome-protecting poly(ADP-ribose) polymerase-1 (PARP-1). Upon activation, PARP-1 consumes high amounts of ATP at a time when this metabolite is scarce, worsening in turn the energy crisis elicited by asphyxia. The energy crisis also impairs ATP-dependent transport, including glutamate re-uptake by astroglia. Nicotinamide, a PARP-1 inhibitor, protects against the metabolic cascade elicited by the primary stage, avoiding NAD+ exhaustion and the energetic crisis. Upon re-oxygenation, however, oxidative stress leads to nuclear translocation of the NF-κB subunit p65, overexpression of the pro-inflammatory cytokines IL-1β and TNF-α, and glutamate-excitotoxicity, due to impairment of glial-glutamate transport, extracellular glutamate overflow, and overactivation of NMDA receptors, mainly of the extrasynaptic type. This leads to calcium influx, mitochondrial impairment, and inactivation of antioxidant enzymes, increasing further the activity of pro-oxidant enzymes, thereby making the surviving neonate vulnerable to recurrent metabolic insults whenever oxidative stress is involved. Here, we discuss evidence showing that (i) inhibition of PARP-1 overactivation by nicotinamide and (ii) inhibition of extrasynaptic NMDA receptor overactivation by memantine can prevent the short- and long-term consequences of PA. These hypotheses have been evaluated in a rat preclinical model of PA, aiming to identify the metabolic cascades responsible for the long-term consequences induced by the insult, also assessing postnatal vulnerability to recurrent oxidative insults. Thus, we present and discuss evidence demonstrating that PA induces long-term changes in metabolic pathways related to energy and oxidative stress, priming vulnerability of cells with both the neuronal and the glial phenotype. The effects induced by PA are region dependent, the substantia nigra being particularly prone to cell death. The issue of short- and long-term consequences of PA provides a framework for addressing a fundamental issue referred to plasticity of the CNS, since the perinatal insult triggers a domino-like sequence of events making the developing individual vulnerable to recurrent adverse conditions, decreasing his/her coping repertoire because of a relevant insult occurring at birth. © 2017, The Author(s).Ítem Vulnerabilidad dependiente de asfixia perinatal de neuronas dopaminérgicas a insultos metabólicos posnatales(Universidad Andrés Bello (Chile), 2015) Sehrt Uribe, Marcos Felipe; Herrera-Marschitz, Mario; Facultad de Medicina; Escuela de Tecnología MédicaAsfixia perinatal implica interrupción del intercambio de gases al momento de nacer, resultando en muerte si la biodisponibilidad de oxígeno no es reestablecida. A pesar de que la pronta re-oxigenación permite revivir al neonato, el insulto produce muerte neuronal y alteraciones neurológicas a largo plazo. Se ha discutido si estas consecuencias a largo plazo de la asfixia perinatal dependen de la duración del insulto, o de cambios en las vías metabólicas que determinan una vulnerabilidad selectiva a insultos metabólicos postnatales que puedan ocurrir a lo largo del desarrollo, limitando la capacidad del sistema nervioso central para responder a factores de estrés metabólicos y/o ambientales. Los mecanismos por los que la asfixia perinatal produciría esta vulnerabilidad no están dilucidados. Por otra parte, se ha observado que la asfixia perinatal no afecta todas las regiones cerebrales por igual, ya que existen regiones privilegiadas en cuanto a reservas energéticas y mecanismos anti-stress, y otras, como los ganglios basales, especialmente vulnerables al daño y malfuncionamiento. Las neuronas dopaminérgicas, que constituyen el sistema pivotal de los ganglios basales, han demostrado ser muy susceptibles a la asfixia perinatal. Los mecanismos de esta susceptibilidad selectiva tampoco están dilucidados. En el presente proyecto, se propone estudiar la vulnerabilidad a un segundo insulto metabólico de las neuronas dopaminérgicas de ratas expuestas a asfixia perinatal, evaluado en cultivos organotípicos, monitoreando los componentes esenciales de los ganglios basales, substantia nigra, neostriado y neocortex, midiendo muerte celular, fenotipo celular y neuroquímico, cuantificando parámetros morfológicos y celulares con microscopia confocal y estereología. Esta investigación determinó que el efecto de un segundo insulto se supedita a las condiciones, grado y tiempo de hipoxia al cual se sometan al nacer.Ítem αVβ3 Integrin regulates astrocyte reactivity(Journal, 2017-09) Lagos-Cabré, Raúl; Alvarez, Alvaro; Kong, Milene; Burgos-Bravo, Francesca; Cárdenas, Areli; Rojas-Mancilla, Edgardo; Pérez-Nuñez, Ramón; Herrera-Molina, Rodrigo; Rojas, Fabiola; Schneider, Pascal; Herrera-Marschitz, Mario; Quest, Andrew F.G.; van Zundert, Brigitte; Leyton, LisetteBackground: Neuroinflammation involves cytokine release, astrocyte reactivity and migration. Neuronal Thy-1 promotes DITNC1 astrocyte migration by engaging αVβ3 Integrin and Syndecan-4. Primary astrocytes express low levels of these receptors and are unresponsive to Thy-1; thus, inflammation and astrocyte reactivity might be necessary for Thy-1-induced responses. Methods: Wild-type rat astrocytes (TNF-activated) or from human SOD1G93A transgenic mice (a neurodegenerative disease model) were used to evaluate cell migration, Thy-1 receptor levels, signaling molecules, and reactivity markers. Results: Thy-1 induced astrocyte migration only after TNF priming. Increased expression of αVβ3 Integrin, Syndecan-4, P2X7R, Pannexin-1, Connexin-43, GFAP, and iNOS were observed in TNF-treated astrocytes. Silencing of β3 Integrin prior to TNF treatment prevented Thy-1-induced migration, while β3 Integrin over-expression was sufficient to induce astrocyte reactivity and allow Thy-1-induced migration. Finally, hSOD1G93A astrocytes behave as TNF-treated astrocytes since they were reactive and responsive to Thy-1. Conclusions: Therefore, inflammation induces expression of αVβ3 Integrin and other proteins, astrocyte reactivity, and Thy-1 responsiveness. Importantly, ectopic control of β3 Integrin levels modulates these responses regardless of inflammation. © 2017 The Author(s).