Improvement in Outcomes After Cardiac Arrest and Resuscitation by Inhibition of S-Nitrosoglutathione Reductase.

BACKGROUND: The biological effects of nitric oxide are mediated via protein S-nitrosylation. Levels of S-nitrosylated protein are controlled in part by the denitrosylase, S-nitrosoglutathione reductase (GSNOR). The objective of this study was to examine whether GSNOR inhibition improves outcomes after cardiac arrest and cardiopulmonary resuscitation (CA/CPR). METHODS: Adult wild-type C57BL/6 and GSNOR-deleted (GSNOR-/-) mice were subjected to potassium chloride-induced CA and subsequently resuscitated. Fifteen minutes after a return of spontaneous circulation, wild-type mice were randomized to receive the GSNOR inhibitor, SPL-334.1, or normal saline as placebo. Mortality, neurological outcome, GSNOR activity, and levels of S-nitrosylated proteins were evaluated. Plasma GSNOR activity was measured in plasma samples obtained from post-CA patients, preoperative cardiac surgery patients, and healthy volunteers. RESULTS: GSNOR activity was increased in plasma and multiple organs of mice, including brain in particular. Levels of protein S-nitrosylation were decreased in the brain 6 hours after CA/CPR. Administration of SPL-334.1 attenuated the increase in GSNOR activity in brain, heart, liver, spleen, and plasma, and restored S-nitrosylated protein levels in the brain. Inhibition of GSNOR attenuated ischemic brain injury and improved survival in wild-type mice after CA/CPR (81.8% in SPL-334.1 versus 36.4% in placebo; log rank P=0.031). Similarly, GSNOR deletion prevented the reduction in the number of S-nitrosylated proteins in the brain, mitigated brain injury, and improved neurological recovery and survival after CA/CPR. Both GSNOR inhibition and deletion attenuated CA/CPR-induced disruption of blood brain barrier. Post-CA patients had higher plasma GSNOR activity than did preoperative cardiac surgery patients or healthy volunteers ( P<0.0001). Plasma GSNOR activity was positively correlated with initial lactate levels in postarrest patients (Spearman correlation coefficient=0.48; P=0.045). CONCLUSIONS: CA and CPR activated GSNOR and reduced the number of S-nitrosylated proteins in the brain. Pharmacological inhibition or genetic deletion of GSNOR prevented ischemic brain injury and improved survival rates by restoring S-nitrosylated protein levels in the brain after CA/CPR in mice. Our observations suggest that GSNOR is a novel biomarker of postarrest brain injury as well as a molecular target to improve outcomes after CA.

S-nitrosoglutathione reductase inhibition regulates allergen-induced lung inflammation and airway hyperreactivity.

Allergic asthma is characterized by Th2 type inflammation, leading to airway hyperresponsivenes, mucus hypersecretion and tissue remodeling. S-Nitrosoglutathione reductase (GSNOR) is an alcohol dehydrogenase involved in the regulation of intracellular levels of S-nitrosothiols. GSNOR activity has been shown to be elevated in human asthmatic lungs, resulting in diminished S-nitrosothiols and thus contributing to increased airway hyperreactivity. Using a mouse model of allergic airway inflammation, we report that intranasal administration of a new selective inhibitor of GSNOR, SPL-334, caused a marked reduction in airway hyperreactivity, allergen-specific T cells and eosinophil accumulation, and mucus production in the lungs in response to allergen inhalation. Moreover, SPL-334 treatment resulted in a significant decrease in the production of the Th2 cytokines IL-5 and IL-13 and the level of the chemokine CCL11 (eotaxin-1) in the airways. Collectively, these observations reveal that GSNOR inhibitors are effective not only in reducing airway hyperresponsiveness but also in limiting lung inflammatory responses mediated by CD4(+) Th2 cells. These findings suggest that the inhibition of GSNOR may provide a novel therapeutic approach for the treatment of allergic airway inflammation.

Phase I study of docosahexaenoic acid-paclitaxel: a taxane-fatty acid conjugate with a unique pharmacology and toxicity profile.

PURPOSE: Docosahexaenoic acid (DHA)-paclitaxel, a novel conjugate formed by covalently linking the natural fatty acid DHA to paclitaxel, was designed as a prodrug targeting intratumoral activation. This Phase I trial examined its toxicity and pharmacokinetics (PKs). EXPERIMENTAL DESIGN: Patients with advanced refractory solid tumors received a 2-h i.v. infusion of DHA-paclitaxel every 3 weeks. Plasma and urine samples were obtained to characterize the pharmacological profile of DHA-paclitaxel and paclitaxel. RESULTS: Twenty-four patients received 78 cycles of DHA-paclitaxel over five dose levels (200-1100 mg/m(2)). Median number of cycles was 2 (range, 1-8). Myelosuppression was the principal toxicity observed (grade 3/4 neutropenia in 21%/53% of courses at 1100 mg/m(2)); during cycle 1, febrile neutropenia occurred in 1 of 9 patients treated at 1100 mg/m(2). Other grade 3 toxicities were infrequent. No patients developed alopecia, peripheral neuropathy > grade 1, or musculoskeletal toxicity > grade 1. At 1100 mg/m(2), DHA-paclitaxel had a mean (CV%) volume of distribution of 7.5 (64) liters, beta half-life of 112 (56) h, and clearance of 0.11 (30) liters/h. Paclitaxel PK parameters at 1100 mg/m(2) were: C(max), 282 (46) ng/ml; AUC, 10,705 (60) ng/ml x h; and terminal half-life, 85 (101) h. Paclitaxel plasma exposure represented < or =0.06% of DHA-paclitaxel exposure. Paclitaxel AUC was correlated with neutropenia. One partial response was observed. CONCLUSIONS: The starting dose recommended for subsequent studies is 1100 mg/m(2). DHA-paclitaxel dramatically alters the PK profile of derived paclitaxel compared with values observed after a 3-h infusion of paclitaxel (175 mg/m(2)). In addition, its favorable toxicity profile offers potential advantages over existing taxanes.