Post-Myocardial Infarction Heart Failure in Closed-chest Coronary Occlusion/Reperfusion Model in G&#246;ttingen Minipigs and Landrace Pigs

The development of heart failure is the most powerful predictor of long-term mortality in patients surviving acute myocardial infarction (MI). There is an ...

Quark Pharmaceuticals, Inc

Hypoxia is an important factor that elicits numerous physiological and pathological responses. One of the major gene expression programs triggered by hypoxia is mediated through hypoxia-responsive transcription factor hypoxia-inducible factor 1 (HIF-1). Here, we report the identification and cloning of a novel HIF-1-responsive gene, designated RTP801. Its strong up-regulation by hypoxia was detected both in vitro and in vivo in an animal model of ischemic stroke. When induced from a tetracycline-repressible promoter, RTP801 protected MCF7 and PC12 cells from hypoxia in glucose-free medium and from H(2)O(2)-triggered apoptosis via a dramatic reduction in the generation of reactive oxygen species. However, expression of RTP801 appeared toxic for nondividing neuron-like PC12 cells and increased their sensitivity to ischemic injury and oxidative stress. Liposomal delivery of RTP801 cDNA to mouse lungs also resulted in massive cell death. Thus, the biological effect of RTP801 overexpression depends on the cell context and may be either protecting or detrimental for cells under conditions of oxidative or ischemic stresses. Altogether, the data suggest a complex type of involvement of RTP801 in the pathogenesis of ischemic diseases.

Identification of a novel hypoxia-inducible factor 1-responsive gene, RTP801, involved in apoptosis.

We report the toxicological and pharmacokinetic properties of the synthetic, small interfering RNA I5NP following intravenous administration in rodents and nonhuman primates. I5NP is designed to act via the RNA interference (RNAi) pathway to temporarily inhibit expression of the pro-apoptotic protein p53 and is being developed to protect cells from acute ischemia/reperfusion injuries such as acute kidney injury that can occur during major cardiac surgery and delayed graft function that can occur following renal transplantation. Following intravenous administration, I5NP was very rapidly cleared from plasma was distributed predominantly to the kidney, with very low levels in liver and other tissues. Doses of 800 mg/kg I5NP in rodents, and 1,000 mg/kg I5NP in nonhuman primates, were required to elicit adverse effects, which in the monkey were isolated to direct effects on the blood that included a sub-clinical activation of complement and slightly increased clotting times. In the rat, no additional adverse effects were observed with a rat analogue of I5NP, indicating that the effects likely represent class effects of synthetic RNA duplexes rather than toxicity related to the intended pharmacologic activity of I5NP. Taken together, these data support clinical testing of intravenous administration of I5NP for the preservation of renal function following acute ischemia/reperfusion injury.

Toxicological and pharmacokinetic properties of chemically modified siRNAs targeting p53 RNA following intravenous administration.

Nous rapportons les propri&eacute;t&eacute;s pharmacologiques et pharmacocin&eacute;tiques de la I5NP ARN interf&eacute;rents synth&eacute;tique, petite suite &agrave; l&#39;administration par voie intraveineuse chez les rongeurs et les primates non humains. I5NP est con&ccedil;u pour agir par la voie de l&#39;interf&eacute;rence (ARNi) RNA temporairement inhiber l&#39;expression de la prot&eacute;ine p53 de pro-apoptotic et vise &agrave; prot&eacute;ger les cellules contre les blessures, isch&eacute;mie aigu&euml;/reperfusion comme l&eacute;sion r&eacute;nale aigu&euml; pouvant survenir pendant une intervention chirurgicale cardiaque majeure et fonction de greffon retard&eacute;e qui peut se produire suite &agrave; une transplantation r&eacute;nale. Apr&egrave;s l&#39;administration par voie intraveineuse, I5NP a &eacute;t&eacute; tr&egrave;s rapidement &eacute;limin&eacute; de plasma a &eacute;t&eacute; distribu&eacute; principalement pour le rein, avec des niveaux tr&egrave;s faibles dans le foie et les autres tissus. Doses de 800 mg/kg I5NP chez les rongeurs et 1 000 mg/kg I5NP chez les primates non humains, devaient provoquer des effets ind&eacute;sirables, ce qui, chez le singe, ont &eacute;t&eacute; isol&eacute;s pour diriger les effets sur le sang qui inclus une sub-clinique activation du compl&eacute;ment et l&eacute;g&egrave;rement augment&eacute; le temps de coagulation. Chez le rat, on a observ&eacute; aucun effet ind&eacute;sirables suppl&eacute;mentaires avec un analogue de rat de I5NP, indiquant que les effets probables repr&eacute;sentent les effets de classe des duplex de RNA synth&eacute;tique plut&ocirc;t que toxicit&eacute; li&eacute;e &agrave; l&#39;activit&eacute; pharmacologique envisag&eacute;e de I5NP. Pris ensemble, ces r&eacute;sultats supportent des tests cliniques sur l&#39;administration intraveineuse de I5NP pour la pr&eacute;servation de la fonction r&eacute;nale apr&egrave;s isch&eacute;mie aigu&euml;/reperfusion.

Propri&eacute;t&eacute;s pharmacologiques et pharmacocin&eacute;tiques de modifi&eacute;s chimiquement siARN ciblant p53 RNA apr&egrave;s administration intraveineuse.

Si riportano le propriet&agrave; tossicologiche e farmacocinetiche della RNA I5NP interferenti sintetico, piccoli dopo somministrazione endovenosa in roditori e primati. I5NP &egrave; progettato per agire attraverso la via di interferenza (RNAi) RNA per inibire temporaneamente l&#39;espressione dei pro-apoptotic proteina p53 ed &egrave; stato sviluppato per proteggere le cellule da lesioni acute ischemia/reperfusion come lesioni renali acute che possono verificarsi durante la chirurgia cardiaca maggiore e funzione di ritardo dell&#39;innesto che pu&ograve; verificarsi a seguito di trapianto renale. A seguito di somministrazione endovenosa, I5NP era molto rapidamente eliminato dal plasma &egrave; stato distribuito principalmente nel rene, con livelli molto bassi nel fegato e altri tessuti. Dosi di 800 mg/kg I5NP in roditori e 1.000 mg/kg I5NP in nonhuman primates, dovevano suscitare effetti avversi, che nella scimmia sono stati isolati per dirigere gli effetti sul sangue che includeva un subcliniche di attivazione del complemento e leggermente aumentato i tempi di coagulazione. Nel ratto, senza ulteriori effetti avversi sono stati osservati con un analogo del ratto di I5NP, che indica che gli effetti probabilmente rappresentano effetti classe di duplex RNA sintetico piuttosto che tossicit&agrave; correlati all&#39;attivit&agrave; farmacologica prevista di I5NP. Presi insieme, questi dati supportano la sperimentazione clinica della somministrazione endovenosa di I5NP per la conservazione della funzione renale dopo lesione acuta ischemia/reperfusion.

Propriet&agrave; tossicologiche e farmacocinetiche di siRNA chimicamente modificati targeting RNA p53 dopo somministrazione per via endovenosa.

Uncoupling protein 1 (Ucp1), which is localized in the mitochondrial inner membrane of mammalian brown adipose tissue (BAT), generates heat by uncoupling oxidative phosphorylation. Upon cold exposure or nutritional abundance, sympathetic neurons stimulate BAT to express Ucp1 to induce energy dissipation and thermogenesis. Accordingly, increased Ucp1 expression reduces obesity in mice and is correlated with leanness in humans. Despite this significance, there is currently a limited understanding of how Ucp1 expression is physiologically regulated at the molecular level. Here, we describe the involvement of Sestrin2 and reactive oxygen species (ROS) in regulation of Ucp1 expression. Transgenic overexpression of Sestrin2 in adipose tissues inhibited both basal and cold-induced Ucp1 expression in interscapular BAT, culminating in decreased thermogenesis and increased fat accumulation. Endogenous Sestrin2 is also important for suppressing Ucp1 expression because BAT from Sestrin2(-/-) mice exhibited a highly elevated level of Ucp1 expression. The redox-inactive mutant of Sestrin2 was incapable of regulating Ucp1 expression, suggesting that Sestrin2 inhibits Ucp1 expression primarily through reducing ROS accumulation. Consistently, ROS-suppressing antioxidant chemicals, such as butylated hydroxyanisole and N-acetylcysteine, inhibited cold- or cAMP-induced Ucp1 expression as well. p38 MAPK, a signaling mediator required for cAMP-induced Ucp1 expression, was inhibited by either Sestrin2 overexpression or antioxidant treatments. Taken together, these results suggest that Sestrin2 and antioxidants inhibit Ucp1 expression through suppressing ROS-mediated p38 MAPK activation, implying a critical role of ROS in proper BAT metabolism. 

Elena Feinstein

Quark Pharmaceuticals, Inc

Post-Myocardial Infarction Heart Failure in Closed-chest Coronary Occlusion/Reperfusion Model in Göttingen Minipigs and Landrace Pigs