Poly (ADP-Ribose) Polymerase Inhibition Attenuates Atherosclerotic Plaque Development In ApoE-/-Mice With Hyperhomocysteinemia

PartⅠPARP Inhibition Decreases Atherosclerotic Lesion size inApoE-/- Mice with HyperhomocysteinemiaObjective Hyperhomocysteinemia (Hhcy) is an important and independent risk factor foratherosclerosis.Recent studies have shown that Poly (ADP-ribose) polymerase (PARP)activation may be associated with Hhcy-induced endothelial dysfunction,which is animportant mechanism for Hhcy to affect atherosclerotic progress.Thus we investigatedwhether PARP inhibitors may decrease the atherosclerotic plaque size in anHhcy-induced experimental animal model with atherosclerosis.Methods Six-week-old homozygous apolipoprotein E-deficient (ApoE-/-) male mice fedwith a normal diet or high methionine-diet were randomly received intraperitonealinjections of 10mg/kg 3-aminobenzamide (3-AB,a kind of PARP inhibitor) dissolvedin PBS,or physiological saline every other day for 12 weeks.Plasma homocysteine(Hcy) levels and lipids contents were measured.Atherosclerotic lesion sizes,thephosphorylation of p47^phox subunit of NADPH oxidase and the expression of PARPprotein and PARP activity were detected. Results Our data demonstrated that the ApoE-/- mice fed with high methionine-dietgenerated Hhcy,which subsequently promoted the oxidative stress-associated DNAdamage and PARP activation,increased atherosclerotic lesion size significantly.Although PARP inhibition by 3-AB did not markedly inhibit the plaque developmentin ApoE-/- mice with spontaneous hyperlipidemia by feeding with a normal diet,itsignificantly reduced atherosclerotic lesion size by 40% in Hhcy-inducedatherosclerosis without affecting plasma homocysteine levels and lipid contents,effectively suppressed PARP activation.Conclusions Our results suggest that PARP inhibition attenuates the atherosclerotic plaquesize in the hyperhomocysteinemic conditions,indicates 3-AB may prove beneficial forthe treatment of atherosclerosis. PartⅡPARP Inhibition Suppress Nuclear Translocation ofNF-κB and Subsequent Production of Inflammatory Factors withinAtherosclerotic PlaquesObjective To investigate whether PARP [Poly (ADP-ribose) polymerase] inhibitor3-aminobenzamide (3-AB) may suppress the nuclear translocation of nuclear factor(NF)-κB and subsequent production of inflammatory factors in the plaque lesions in anHhcy (hyperhomocysteinemia)-induced experimental animal model withatherosclerosis.Methods Six-week-old homozygous apolipoprotein E-deficient (ApoE-/-) male mice fedwith a normal diet or high methionine-diet were randomly received intraperitonealinjections of 10mg/kg 3-aminobenzamide (3-AB,a kind of PARP inhibitor) dissolvedin PBS,or physiological saline every other day for 12 weeks.Plasma homocysteine(Hcy) levels and lipids contents were measured.Then hearts and aortas were removedrapidly.The thoracic and abdominal aorta was quick-frozen in nitrogen for laterextraction of protein and RNA.The expression of NF-κB p65,inhibitors ofκB (IκB),and phospho-inhibitors ofκB (p-IκB) in total proteins,cytoplasmic extracts andnuclear extracts was measured.The expression of VCAM-1 and MCP-1 withinplaques was also detected by Immunohistochemistry analysis,Westem Blot analysisand real-time reverse-transcription PCR.Results Our data demonstrated that the ApoE-/- mice fed with high methionine-dietgenerated Hhcy,which significantly increased the expression of NF-κB p65 in nuclearextracts and p-IκB in total proteins,promoted the nuclear translocation of NF-κB,thereby increased the subsequent production of inflammatory factors within plaquessuch as VCAM-1 and MCP-1.Although PARP inhibition by 3-AB did not markedlyinhibit the nuclear translocation of NF-κB in ApoE-/- mice with spontaneous hyperlipidemia by feeding with a normal diet,it significantly reduced the activity ofNF-κB in Hhcy-induced atherosclerosis without affecting plasma homocysteine levelsand lipid contents,effectively suppressed subsequent production of VCAM-1 andMCP-1.Conclusions Our results suggest that PARP inhibition suppress the nuclear translocation ofNF-κB and subsequent production of inflammatory factors in the atheroscleroticplaques in the hyperhomocysteinemic conditions. PartⅢPARP Inhibition Promotes Apoptosis withinAtherosclerotic PlaquesObjective To investigate whether PARP [Poly (ADP-ribose) polymerase] inhibitor3-aminobenzamide (3-AB) effects on the apoptosis within the atherosclerotic plaquesin an Hhcy (hyperhomocysteinemia)-induced experimental animal model withatherosclerosis.Methods Six-week-old homozygous apolipoprotein E-deficient (ApoE-/-) male mice fedwith a normal diet or high methionine-diet were randomly received intraperitonealinjections of 10mg/kg 3-aminobenzamide (3-AB,a kind of PARP inhibitor) dissolvedin PBS,or physiological saline every other day for 12 weeks.Plasma homocysteine(Hcy) levels and lipids contents were measured.Then hearts and aortas were removedrapidly.The thoracic and abdominal aorta was quick-frozen in nitrogen for laterextraction of protein and RNA.Apoptotic cells were detected by Apoptosis DetectionKit;the expression of caspase-3 within plaques was measured by Western Blotanalysis.Results Our data demonstrated that the ApoE-/- mice fed with high methionine-dietgenerated Hhcy.The apoptotic cells were highly increased in Hhcy condition whichwas detected by Apoptosis Detection Kit.Although PARP inhibition by 3-AB did notmarkedly have effect on apoptosis in ApoE-/- mice with spontaneous hyperlipidemiaby feeding with a normal diet,it significantly incrased the depletion of na(?)ve caspase-3, aggravated the caspase-3 activation,made the mode of cell death be prone to apoptosisin Hhcy-induced atherosclerosis without affecting plasma homocysteine levels andlipid contents.Conclusions Our results suggest that PARP inhibition aggravated the caspase-3 activation,promoted the apoptosis in the atherosclerotic plaques in the hyperhomocysteinemicconditions.