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Published on: October 12, 2017
Poly(ADP-ribose) polymerase inhibition improves endothelial dysfunction induced by reactive oxidant hydrogen peroxide
Tamás Radovits1, Li-ni Lin, Julia Zotkina
1Laboratory of Cardiac Surgery, Department of Cardiac Surgery, University of Heidelberg, OG 2, 69120 Heidelberg, Germany.
Abstract:
Reactive oxygen species, such as hydrogen peroxide (H(2)O(2)) induce oxidative stress and DNA-injury. The subsequent activation of poly(ADP-ribose) polymerase (PARP) has been implicated in the pathogenesis of various cardiovascular diseases including ischaemia-reperfusion injury, circulatory shock, diabetic complications and atherosclerosis. We investigated the effect of PARP-inhibition on endothelial dysfunction induced by H(2)O(2). In vascular reactivity measurements on isolated rat aortic rings we investigated the phenylephrine-induced contraction, and endothelium-dependent and -independent vasorelaxation by using cumulative concentrations of acetylcholine and sodium nitroprusside. Endothelial dysfunction was induced by exposing the rings to H(2)O(2) (200 and 400 muM) for 30 min. In the treatment group, rings were preincubated with the potent PARP-inhibitor INO-1001. DNA strand breaks were assessed by the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) method. Immunohistochemical analysis was performed for poly(ADP-ribose) (the enzymatic product of PARP) and for apoptosis inducing factor (a pro-apoptotic factor regulated by PARP). Exposure to H(2)O(2) resulted in reduced contraction forces and a dose-dependent impairment of endothelium-dependent vasorelaxation of aortic rings (maximal relaxation to acetylcholine: 86.21+/-1.574% control vs. 72.55+/-1.984% H(2)O(2) 200 muM vs. 66.86+/-1.961% H(2)O(2) 400 muM; P<0.05). PARP-inhibition significantly improved the acetylcholine-induced vasorelaxation (77.75+/-3.019% vs. 66.86+/-1.961%; P<0.05), while the contractility remained unaffected. The dose-response curves of endothelium-independent vasorelaxation to sodium nitroprusside did not differ in any groups studied. In the H(2)O(2) groups immunohistochemical analysis showed enhanced PARP-activation and nuclear translocation of apoptosis inducing factor, which were prevented by INO-1001. Our results demonstrate that PARP activation contributes to the pathogenesis of H(2)O(2)-induced endothelial dysfunction, which can be prevented by PARP inhibitors.
Insights
Hydrogen peroxide (H2O2) causes endothelial dysfunction by activating poly(ADP-ribose) polymerase (PARP). PARP inhibition with INO-1001 protected against H2O2-induced impairment of vasorelaxation, suggesting a therapeutic role for PARP inhibitors in cardiovascular diseases.
Area of Science:
- Cardiovascular Science
- Molecular Biology
- Oxidative Stress Research
Background:
- Reactive oxygen species, like hydrogen peroxide (H2O2), induce oxidative stress and DNA damage.
- Poly(ADP-ribose) polymerase (PARP) activation is linked to cardiovascular diseases such as ischemia-reperfusion injury and atherosclerosis.
Purpose of the Study:
- To investigate the impact of PARP inhibition on H2O2-induced endothelial dysfunction.
- To explore the role of PARP activation in the pathogenesis of H2O2-mediated vascular injury.
Main Methods:
- Vascular reactivity studies on isolated rat aortic rings.
- Assessment of phenylephrine-induced contraction and endothelium-dependent/independent vasorelaxation.
- Immunohistochemical analysis for PARP activation and apoptosis-inducing factor (AIF) translocation.
Main Results:
- H2O2 exposure impaired endothelium-dependent vasorelaxation in a dose-dependent manner.
- PARP inhibition with INO-1001 significantly improved vasorelaxation without affecting contractility.
- H2O2 increased PARP activation and AIF nuclear translocation, effects reversed by INO-1001.
Conclusions:
- PARP activation contributes significantly to H2O2-induced endothelial dysfunction.
- PARP inhibitors represent a potential therapeutic strategy for mitigating oxidative stress-related vascular damage.
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