title: Echinocystic acid, isolated from Gleditsia sinensis fruit, protects endothelial progenitor cells from damage caused by oxLDL via the Akt/eNOS pathway.
abstract: OBJECTIVE
  Our previous studies revealed that echinocystic acid (EA) showed obvious attenuation of atherosclerosis in rabbits fed a high-fat diet. However, the underlying mechanisms remain to be elucidated. Considering the importance of endothelial progenitor cells (EPCs) in atherosclerosis, we hypothesise that EPCs may be one of the targets for the anti-atherosclerotic potential of EA.
  
  
  METHODS
  After in vitro cultivation, EPCs were exposed to 100 μg/mL of oxidised low-density lipoprotein (oxLDL) and incubated with or without EA (5 and 20 μM) for 48 h. An additional two groups of EPCs (oxLDL+20 μM EA) were pre-treated with either wortmannin, an inhibitor of the phosphoinositide 3-kinase (PI3K) pathway, or nitro-l-arginine methyl ester (l-NAME), an endothelial nitric oxide synthase (eNOS)-specific inhibitor. Assessment of EPC apoptosis, adhesion, migration, and nitric oxide (NO) release was performed using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) staining, cell counting, caspase-3 activity assay, transwell chamber assay, and Griess reagent, respectively. The protein expression of protein kinase B (Akt) and eNOS was detected using Western blot.
  
  
  RESULTS
  Treatment of EPCs with oxLDL induced significant apoptosis and impaired adhesion, migration, and NO production. The deleterious effects of oxLDL on EPCs were attenuated by EA. However, when EPCs were pre-treated with wortmannin or l-NAME, the effects of EA were abrogated. Additionally, oxLDL significantly down-regulated eNOS protein expression as well as repression of eNOS and Akt phosphorylation.
  
  
  CONCLUSIONS
  The inhibitory effect of oxLDL on Akt/eNOS phosphorylation was attenuated by EA. Taken together, the results indicate that EA protects EPCs from damage caused by oxLDL via the Akt/eNOS pathway.
authors.affiliation: School of Bioengineering, Xihua University, Chengdu, China. Electronic address: lai211@sina.com.
authors.forename: Peng
authors.initials: P
authors.lastname: Lai
authors.affiliation: Department of Geriatrics, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Yixin
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000704:Analysis of Variance; D000730:Androstadienes; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002448:Cell Adhesion / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D042783:Endothelial Cells / Q000187:drug effects*; D005638:Fruit / Q000737:chemistry*; D031501:Gleditsia / Q000737:chemistry*; D020287:In Situ Nick-End Labeling; D008077:Lipoproteins, LDL; D008297:Male; D015394:Molecular Structure; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D009828:Oleanolic Acid / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013234:Stem Cells / Q000187:drug effects*; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D008077:Lipoproteins, LDL; D010936:Plant Extracts; C099252:oxidized low density lipoprotein; D009569:Nitric Oxide; D009828:Oleanolic Acid; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt; C022999:echinocystic acid; D019331:NG-Nitroarginine Methyl Ester; D000077191:Wortmannin
keywords: Akt/eNOS; echinocystic acid; endothelial progenitor cells; oxidised low-density lipoprotein