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Protective effects of PARP-1 knockout on dyslipidemia-induced autonomic and vascular dysfunction in ApoE mice: effects on eNOS and oxidative stress.

ABSTRACT: The aims of this study were to investigate the role of poly(ADP-ribose) polymerase (PARP)-1 in dyslipidemia-associated vascular dysfunction as well as autonomic nervous system dysregulation. Apolipoprotein (ApoE)(-/-) mice fed a high-fat diet were used as a model of atherosclerosis. Vascular and autonomic functions were measured in conscious mice using telemetry. The study revealed that PARP-1 plays an important role in dyslipidemia-associated vascular and autonomic dysfunction. Inhibition of this enzyme by gene knockout partially restored baroreflex sensitivity in ApoE(-/-) mice without affecting baseline heart-rate and arterial pressure, and also improved heart-rate responses following selective blockade of the autonomic nervous system. The protective effect of PARP-1 gene deletion against dyslipidemia-induced endothelial dysfunction was associated with preservation of eNOS activity. Dyslipidemia induced PARP-1 activation was accompanied by oxidative tissue damage, as evidenced by increased expression of iNOS and subsequent protein nitration. PARP-1 gene deletion reversed these effects, suggesting that PARP-1 may contribute to vascular and autonomic pathologies by promoting oxidative tissue injury. Further, inhibition of this oxidative damage may account for protective effects of PARP-1 gene deletion on vascular and autonomic functions. This study demonstrates that PARP-1 participates in dyslipidemia-mediated dysregulation of the autonomic nervous system and that PARP-1 gene deletion normalizes autonomic and vascular dysfunctions. Maintenance of eNOS activity may be associated with the protective effect of PARP-1 gene deletion against dyslipidemia-induced endothelial dysfunction.

SUBMITTER: Hans CP

PROVIDER: S-EPMC2757717 | biostudies-literature | 2009 Oct

REPOSITORIES: biostudies-literature

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Protective effects of PARP-1 knockout on dyslipidemia-induced autonomic and vascular dysfunction in ApoE mice: effects on eNOS and oxidative stress.

Hans Chetan P CP Feng Yumei Y Naura Amarjit S AS Zerfaoui Mourad M Rezk Bashir M BM Xia Huijing H Kaye Alan D AD Matrougui Khalid K Lazartigues Eric E Boulares A Hamid AH

PloS one 20091013 10

The aims of this study were to investigate the role of poly(ADP-ribose) polymerase (PARP)-1 in dyslipidemia-associated vascular dysfunction as well as autonomic nervous system dysregulation. Apolipoprotein (ApoE)(-/-) mice fed a high-fat diet were used as a model of atherosclerosis. Vascular and autonomic functions were measured in conscious mice using telemetry. The study revealed that PARP-1 plays an important role in dyslipidemia-associated vascular and autonomic dysfunction. Inhibition of th ...[more]

PMID: 19823587

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Project description:Background Hypertension and vascular toxicity are major unwanted side effects of antiangiogenic drugs, such as vascular endothelial growth factor inhibitors (VEGFis), which are effective anticancer drugs but have unwanted side effects, including vascular toxicity and hypertension. Poly (ADP-ribose) polymerase (PARP) inhibitors, used to treat ovarian and other cancers, have also been associated with elevated blood pressure. However, when patients with cancer receive both olaparib, a PARP inhibitor, and VEGFi, the risk of blood pressure elevation is reduced. Underlying molecular mechanisms are unclear, but PARP-regulated transient receptor potential cation channel, subfamily M, member 2 (TRPM2), a redox-sensitive calcium channel, may be important. We investigated whether PARP/TRPM2 plays a role in VEGFi-induced vascular dysfunction and whether PARP inhibition ameliorates the vasculopathy associated with VEGF inhibition. Methods and Results Human vascular smooth muscle cells (VSMCs), human aortic endothelial cells, and wild-type mouse mesenteric arteries were studied. Cells/arteries were exposed to axitinib (VEGFi) alone and in combination with olaparib. Reactive oxygen species production, Ca2+ influx, protein/gene analysis, PARP activity, and TRPM2 signaling were assessed in VSMCs, and nitric oxide levels were determined in endothelial cells. Vascular function was assessed by myography. Axitinib increased PARP activity in VSMCs in a reactive oxygen species-dependent manner. Endothelial dysfunction and hypercontractile responses were ameliorated by olaparib and a TRPM2 blocker (8-Br-cADPR). VSMC reactive oxygen species production, Ca2+ influx, and phosphorylation of myosin light chain 20 and endothelial nitric oxide synthase (Thr495) were augmented by axitinib and attenuated by olaparib and TRPM2 inhibition. Proinflammatory markers were upregulated in axitinib-stimulated VSMCs, which was reduced by reactive oxygen species scavengers and PARP-TRPM2 inhibition. Human aortic endothelial cells exposed to combined olaparib and axitinib showed nitric oxide levels similar to VEGF-stimulated cells. Conclusions Axitinib-mediated vascular dysfunction involves PARP and TRPM2, which, when inhibited, ameliorate the injurious effects of VEGFi. Our findings define a potential mechanism whereby PARP inhibitor may attenuate vascular toxicity in VEGFi-treated patients with cancer.

Project description:Alzheimer's disease (AD) is the most common form of dementia and the leading risk factor, after age, is possession of the apolipoprotein E epsilon 4 allele (APOE4). Approximately 50% of AD patients carry one or two copies of APOE4 but the mechanisms by which it confers risk are still unknown. APOE4 carriers are reported to demonstrate changes in brain structure, cognition, and neuropathology, but findings have been inconsistent across studies. In the present study, we used multi-modal data to characterise the effects of APOE4 on the brain, to investigate whether AD pathology manifests differently in APOE4 carriers, and to determine if AD pathomechanisms are different between carriers and non-carriers. Brain structural differences in APOE4 carriers were characterised by applying machine learning to over 2000 brain MRI measurements from 33,384 non-demented UK biobank study participants. APOE4 carriers showed brain changes consistent with vascular dysfunction, such as reduced white matter integrity in posterior brain regions. The relationship between APOE4 and AD pathology was explored among the 1260 individuals from the Religious Orders Study and Memory and Aging Project (ROSMAP). APOE4 status had a greater effect on amyloid than tau load, particularly amyloid in the posterior cortical regions. APOE status was also highly correlated with cerebral amyloid angiopathy (CAA). Bulk tissue brain transcriptomic data from ROSMAP and a similar dataset from the Mount Sinai Brain Bank showed that differentially expressed genes between the dementia and non-dementia groups were enriched for vascular-related processes (e.g., "angiogenesis") in APOE4 carriers only. Immune-related transcripts were more strongly correlated with AD pathology in APOE4 carriers with some transcripts such as TREM2 and positively correlated with pathology severity in APOE4 carriers, but negatively in non-carriers. Overall, cumulative evidence from the largest neuroimaging, pathology, and transcriptomic studies available suggests that vascular dysfunction is key to the development of AD in APOE4 carriers. However, further studies are required to tease out non-APOE4-specific mechanisms.

Dataset Information

Protective effects of PARP-1 knockout on dyslipidemia-induced autonomic and vascular dysfunction in ApoE mice: effects on eNOS and oxidative stress.

Publications

Protective effects of PARP-1 knockout on dyslipidemia-induced autonomic and vascular dysfunction in ApoE mice: effects on eNOS and oxidative stress.

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