Inhibition of Inducible Nitric-Oxide Synthase Protects Human T Cells from Hypoxia-Induced Apoptosis

Armed Forces Radiobiology Research Institute, Bldg. 46, Room 2423, 8901 Wisconsin Ave., Bethesda, MD 20889-5603, USA.
Molecular pharmacology (Impact Factor: 4.13). 04/2008; 73(3):738-47. DOI: 10.1124/mol.107.041079
Source: PubMed


Sodium cyanide-induced chemical hypoxia triggers a series of biochemical alterations leading to apoptosis in many cell types, including T cells. It is known that chemical hypoxia promotes inducible nitric-oxide synthase (iNOS) gene transcription by activating its transcription factors. To determine whether iNOS and NO production are responsible for chemical hypoxia-induced apoptosis, we exposed human Jurkat T cells to sodium cyanide in the presence or absence of iNOS inhibitors. We found that iNOS expression is necessary for hypoxia-induced lipid peroxidation and leukotriene B(4) generation. The inhibition of iNOS limited T-cell apoptosis by decreasing the activity of caspase-3 without affecting the expression of Fas/Apo-1/CD95 on the surface membrane of T cells. These data suggest iNOS-mediated NO produced endogenously in the T cell alters overall T-cell function and results in apoptosis. Proper control of iNOS expressed in the T cell may represent a useful approach to immunomodulation.

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    • "The complex role of Hsp70 is not fully known, but according to Aggarwal et al. (2012), one of their main tasks is protection against damage to intracellular structures in organs exposed to severe stress. Other authors (Snoeckx et al. 2001, Kiang et al. 2008) have found increased expression of Hsp70 to be significantly correlated with a reduction in destructive changes in the heart muscle of rats, which may be an important element in preventing myocardial infarction in humans. It should also be emphasized that the concentration of protective Hsp70 in internal organs can undergo significant changes over time; this was demonstrated in a study by Zhang et al. (2012), in which a significant decrease was observed in the concentration of this protein in the liver and stomach of pigs slaughtered 4 hours after transport . "
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    ABSTRACT: In view of the significant role of Hsp70 in protecting the organism against the destructive effects of stress, and the possibility of using this protein as a marker of the infarction process in the heart, the aim of this study was to conduct an evaluation of the expression of 70kDa heat shock proteins (Hsp70) and the concentration of TBARS (thiobarbituric acid reactive substances) and nitric oxide ions (NO), determined as nitrite ions, as markers of oxidative stress in hearts obtained from healthy pigs following slaughter and pigs which had died during or immediately after transport with symptoms of sudden cardiac death. The material consisted of hearts obtained from 90 pigs following slaughter and from pigs which had died. Oxidative stress was determined in heart lysates based on the concentration of TBARS and nitrite ions. Expression and concentration of Hsp70 were determined using SDS-PAGE, Western blotting, and ELISA. Expression of Hsp70 was observed in hearts lysates obtained from slaughtered pigs and from those which had died with symptoms of sudden death. The strongest reaction in the Western Blotting was noted in hearts lysates from pigs with no pathological changes. The highest TBARS concentration was observed in lysates from hearts in pigs which had died during or immediately after transport. The highest concentration of NO ions, determined as nitrite ions, was noted in hearts from pigs with myocardial infarction lesions. The significant decrease observed in Hsp70 concentration in heart tissue obtained from the pigs which had died in comparison to the hearts from healthy pigs indicates the important role of this protein in protecting the heart muscle against the destructive effects of stress, which limits the occurrence of post-stress cardiomyopathy in pigs following transport.
    Full-text · Article · Oct 2014 · Polish journal of veterinary sciences
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    • "Increases in NO occur when iNOS is induced. H/R upregulates iNOS, an NF-κB-dependent protein [63, 64]. To further evaluate the mechanism that contributes to the production of RONS in our model, we examined the expression of iNOS after ethanol gavage and H/R. "
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    ABSTRACT: Acute ethanol intoxication increases the production of reactive oxygen species (ROS). Hemorrhagic shock with subsequent resuscitation (H/R) also induces ROS resulting in cellular and hepatic damage in vivo. We examined the role of acute ethanol intoxication upon oxidative stress and subsequent hepatic cell death after H/R. 14 h before H/R, rats were gavaged with single dose of ethanol or saline (5 g/kg, EtOH and ctrl; H/R_EtOH or H/R_ctrl, resp.). Then, rats were hemorrhaged to a mean arterial blood pressure of 30 ± 2 mmHg for 60 min and resuscitated. Two control groups underwent surgical procedures without H/R (sham_ctrl and sham_EtOH, resp.). Liver tissues were harvested at 2, 24, and 72 h after resuscitation. EtOH-gavage induced histological picture of acute fatty liver. Hepatic oxidative (4-hydroxynonenal, 4-HNE) and nitrosative (3-nitrotyrosine, 3-NT) stress were significantly reduced in EtOH-gavaged rats compared to controls after H/R. Proapoptotic caspase-8 and Bax expressions were markedly diminished in EtOH-gavaged animals compared with controls 2 h after resuscitation. EtOH-gavage increased antiapoptotic Bcl-2 gene expression compared with controls 2 h after resuscitation. iNOS protein expression increased following H/R but was attenuated in EtOH-gavaged animals after H/R. Taken together, the data suggest that acute EtOH-gavage may attenuate H/R-induced oxidative stress thereby reducing cellular injury in rat liver.
    Full-text · Article · Apr 2012 · Oxidative Medicine and Cellular Longevity
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    • "Hemorrhage upregulates iNOS as a result of increases in c-jun, KLF6, and NF-kB and a decrease in KLF4 [4,5]. Increased iNOS elevates NO production, protein nitration, lipid peroxidation, apoptosome formation, and caspase activation; thereby leading to caspase-dependent apoptosis [4,5]. "
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    ABSTRACT: Hemorrhage increases inducible nitric oxide synthase (iNOS) and depletes ATP levels in various tissues. Previous studies have shown that geldanamycin, an inducer of heat shock protein 70kDa (HSP-70) and inhibitor of iNOS, limits both processes. Reduction in NO production limits lipid peroxidation, apoptosome formation, and caspase-3 activation, thereby increasing cellular survival and reducing the sequelae of hemorrhage. The poor solubility of geldanamycin in aqueous solutions, however, limits its effectiveness as a drug. 17-DMAG is a water-soluble analog of geldanamycin that might have greater therapeutic utility. This study investigated the effectiveness of 17-DMAG at reducing hemorrhagic injury in mouse small intestine. In mice, the hemorrhage-induced iNOS increase correlated with increases in Kruppel-like factor 6 (KLF6) and NF-kB and a decrease in KLF4. As a result, increases in NO production and lipid peroxidation occurred. Moreover, hemorrhage also resulted in decreased Bcl-2 and increased TNF-α, IL-6, and IL-10 concentrations, p53 protein, caspase-3 activation, and cellular ATP depletion. A shortening and widening of villi in the small intestine was also observed. Treatment with 17-DMAG significantly reduced the hemorrhage-induced increases in iNOS protein, jejunal alteration, and TNF-α and IL-10 concentrations, but 17-DMAG did not affect the hemorrhage-induced increases in p53 and IL-6 concentration. 17-DMAG treatment by itself upregulated HSP-70, Bcl-2, and p53. Since 17-DMAG is water soluble, bioactive, and not toxic, 17-DMAG may prove useful as a prophylactic drug for hemorrhage.
    Full-text · Article · Jun 2011 · Cell and Bioscience
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