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Martinez-Romero R.,University of Jaen | Canuelo A.,University of Jaen | Siles E.,University of Jaen | Oliver F.J.,Institute of Parasitology and Biomedicine | Martinez-Lara E.,University of Jaen
Journal of Applied Physiology | Year: 2012

The physiological response to hypobaric hypoxia represents a complex network of biochemical pathways in which the nitrergic system plays an important role. Previous studies have provided evidence for an interplay between the hypoxia-inducible factor-1 (HIF-1) and poly(ADP-ribose) polymerase-1 (PARP-1) under hypoxia. Here, we evaluate the potential involvement of nitric oxide (NO) in the cross talk between these two proteins. With this aim, we studied comparatively the effect of pharmacological inhibitors of NO production or PARP activity in the response of the mouse cerebral cortex to 4 h of exposure to a simulated altitude of 31,000 ft. Particularly, we analyzed the NO and reactive oxygen species production, the expression of NO synthase (NOS) isoforms, PARP-1 activity, HIF-1α expression and HIF-1 transcriptional activity, the protein level of the factor inhibiting HIF, and, finally, beclin-1 and fractin expression, as markers of cellular damage. Our results demonstrate that the reduction of NO level did not affect reactive oxygen species production but significantly 1) dampened the posthypoxic increase in neuronal NOS and inducible NOS expression without altering endothelial NOS protein level; 2) prevented PARP activation; 3) decreased HIF-1α response to hypoxia; 4) achieved a higher long-term HIF-1 transcriptional activity by reducing factor inhibiting HIF expression; and 5) reduced hypoxic damage. The pharmacological inhibition of PARP reproduced the NOS expression pattern and the HIF-1α response observed in NOSinhibited mice, supporting its involvement in the NO-dependent regulation of hypoxia. As a whole, these results provide new data about the molecular mechanism underlying the beneficial effects of controlling NO production under hypobaric hypoxic conditions. Copyright © 2012 the American Physiological Society. Source

Bienvenu A.-L.,University of Lyon | Gonzalez-Rey E.,Institute of Parasitology and Biomedicine | Picot S.,University of Lyon
Parasites and Vectors | Year: 2010

Fatalities caused by parasitic infections often occur as a result of tissue injury that results from a form of host-cell death known as apoptosis. However, instead of being pathogenic, parasite-induced apoptosis may facilitate host survival. Consequently, it is of utmost importance to decipher and understand the process and the role of apoptosis induced or controlled by parasites in humans. Despite this, few studies provide definitive knowledge of parasite-induced host-cell apoptosis. Here, the focus is on a consideration of host-cell apoptosis as either a pathogenic feature or as a factor enabling parasite survival and development. Cell death by apoptotic-like mechanisms could be described as a ride to death with a return ticket, as initiation of the pathway may be reversed, with the potential that it could be manipulated for therapeutic purposes. The management of host-cell apoptosis could thus be an adjunctive factor for parasitic disease treatment. Evidence that the apoptotic process could be reversed by anti-apoptotic drugs has recently been obtained, leading to the possibility of host-cell rescue after injury. An important issue will be to predict the beneficial or deleterious effects of controlling human cell death by apoptotic-like mechanisms during parasitic diseases. © 2010 Bienvenu et al; licensee BioMed Central Ltd. Source

Chan N.,University of Toronto | Pires I.M.,University of Oxford | Bencokova Z.,University of Oxford | Coackley C.,University of Toronto | And 8 more authors.
Cancer Research | Year: 2010

Acute and chronic hypoxia exists within the three-dimensional microenvironment of solid tumors and drives therapy resistance, genetic instability, and metastasis. Replicating cells exposed to either severe acute hypoxia (16 hours with 0.02% O2) followed by reoxygenation or moderate chronic hypoxia (72 hours with 0.2% O2) treatments have decreased homologous recombination (HR) protein expression and function. As HR defects are synthetically lethal with poly(ADP-ribose) polymerase 1 (PARP1) inhibition, we evaluated the sensitivity of repair-defective hypoxic cells to PARP inhibition. Although PARP inhibition itself did not affect HR expression or function, we observed increased clonogenic killing in HR-deficient hypoxic cells following chemical inhibition of PARP1. This effect was partially reversible by RAD51 overexpression. PARP1-/- murine embryonic fibroblasts (MEF) showed a proliferative disadvantage under hypoxic gassing when compared with PARP1+/+ MEFs. PARP-inhibited hypoxic cells accumulated γH2AX and 53BP1 foci as a consequence of altered DNA replication firing during S phase-specific cell killing. In support of this proposed mode of action, PARP inhibitor-treated xenografts displayed increased γH2AX and cleaved caspase-3 expression in RAD51-deficient hypoxic subregions in vivo, which was associated with decreased ex vivo clonogenic survival following experimental radiotherapy. This is the first report of selective cell killing of HR-defective hypoxic cells in vivo as a consequence of microenvironment-mediated "contextual synthetic lethality." As all solid tumors contain aggressive hypoxic cells, this may broaden the clinical utility of PARP and DNA repair inhibition, either alone or in combination with radiotherapy and chemotherapy, even in tumor cells lacking synthetically lethal, genetic mutations. ©2010 AACR. Source

Prasse A.,University Hospital Freiburg | Zissel G.,University Hospital Freiburg | Lutzen N.,University Hospital Freiburg | Schupp J.,University Hospital Freiburg | And 8 more authors.
American Journal of Respiratory and Critical Care Medicine | Year: 2010

Rationale: Previous studies suggest an important immunoregulatory role of vasoactive intestinal peptide (VIP) in experimental models of chronic noninfectious inflammation. Sarcoidosis is characterized by noncaseating epitheloid cell granulomas, where excessive tumor necrosis factor-α production by pulmonary macrophages plays a critical role in granuloma formation and disease progression, which may lead to fatal organ dysfunction. Objectives: To test whether inhaled VIP has an immunoregulatory role. Sarcoid alveolitis was used as a prototype of immune-mediated chronic lung inflammation. Methods: In an open clinical phase II study, we treated 20 patients with histologically proved sarcoidosis and active disease with nebulized VIP for 4 weeks. Measurements and Main Results: VIP inhalation was safe, well-tolerated, and significantly reduced the production of tumor necrosis factor-α by cells isolated from bronchoalveolar lavage fluids of these patients. VIP treatment significantly increased the numbers of bronchoalveolar lavage CD4 +CD127-CD25+ T cells, which showed regulatory activities on conventional effector T cells. In vitro experiments demonstrated the capacity of VIP to convert naive CD4+CD25- T cells into CD4+CD25+FoxP3+ regulatory T cells, suggesting the generation of peripheral regulatory T cells by VIP treatment. Conclusions: This study is the first to show the immunoregulatory effect of VIP in humans, and supports the notion of inhaled VIP as an attractive future therapy to dampen exaggerated immune responses in lung disorders. Thus, the inhalation of neuropeptides may be developed into a new therapeutic principle for chronic inflammatory lung disorders in humans. Source

Del Moral R.M.G.,Provincial UGC Intercentre | Gomez-Morales M.,Provincial UGC Intercentre | Hernandez-Cortes P.,University of Granada | Aguilar D.,University of Granada | And 11 more authors.
The Scientific World Journal | Year: 2013

We test the hypothesis that PARP inhibition can decrease acute tubular necrosis (ATN) and other renal lesions related to prolonged cold ischemia/reperfusion (IR) in kidneys preserved at 4°C in University of Wisconsin (UW) solution. Material and Methods. We used 30 male Parp1 +/+ wild-type and 15 male Parp10/0 knockout C57BL/6 mice. Fifteen of these wild-type mice were pretreated with 3,4-dihydro-5-[4-(1- piperidinyl)butoxyl]-1(2H)-isoquinolinone (DPQ) at a concentration of 15 mg/kg body weight, used as PARP inhibitor. Subgroups of mice were established (A: IR 45 min/6 h; B: IR + 48 h in UW solution; and C: IR + 48 h in UW solution plus DPQ). We processed samples for morphological, immunohistochemical, ultrastructural, and western-blotting studies. Results. Prolonged cold ischemia time in UW solution increased PARP-1 expression and kidney injury. Preconditioning with PARP inhibitor DPQ plus DPQ supplementation in UW solution decreased PARP-1 nuclear expression in renal tubules and renal damage. Parp10/0 knockout mice were more resistant to IR-induced renal lesion. In conclusion, PARP inhibition attenuates ATN and other IR-related renal lesions in mouse kidneys under prolonged cold storage in UW solution. If confirmed, these data suggest that pharmacological manipulation of PARP activity may have salutary effects in cold-stored organs at transplantation. © 2013 Raimundo M. G. del Moral et al. Source

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