title: The protective effect of Smilax glabra extract on advanced glycation end products-induced endothelial dysfunction in HUVECs via RAGE-ERK1/2-NF-κB pathway.
abstract: BACKGROUND
  Smilax glabra Roxb. (SGR) is a traditional Chinese herb that has been used in folk for the treatment of diabetic vascular complications. Advanced glycation end products (AGEs)-induced endothelial dysfunction has been thought to be a major cause of diabetic vascular complications. The present study was conducted to investigate the protective effect of SGR extract on AGEs-induced endothelial dysfunction and its underlying mechanisms.
  
  
  METHODS
  Human umbilical vein endothelial cells (HUVECs) were exposed to 200 μg/ml AGEs to induce endothelial dysfunction. Acridine orange/ethidium bromide (AO/EB) fluorescence assay and Annexin-V/PI double-staining were performed to determine endothelium apoptosis. Dihydroethidium (DHE) fluorescence probe, SOD and MDA kits were used to evaluate oxidative stress. The effect of SGR extract on AGEs-induced TGF-beta1 expression was determined by immunocytochemistry and western blotting. Attenuations of SGR extract on receptor for AGEs (RAGE) expression, extracellular regulated protein kinases (ERK1/2) activation and NF-κB phosphorylation were determined by immunofluorescence assay and western blotting. The blockade assays for RAGE and ERK1/2 were carried out using a specific RAGE-antibody (RAGE-Ab) or a selective ERK1/2 inhibitor PD98059 in immunofluorescence assay.
  
  
  RESULTS
  The pretreatment of SGR extract (0.125, 0.25 and 0.5 mg crude drug/ml) significantly attenuated AGEs-induced endothelium apoptosis, and down-regulated TGF-beta1 protein expression in HUVECs. It was also well shown that SGR extract could down-regulate dose-dependently ROS over-generation, MDA content, TGF-beta1 expression, ERK1/2 and NF-κB activation whereas increase significantly SOD activity. Furthermore, the AGEs-induced ERK1/2 activation could be attenuated by the blockade of RAGE-Ab (5 μg/ml) while the NF-κB activation was ameliorated by ERK1/2 inhibitor PD98059 (10 μM).
  
  
  CONCLUSIONS
  These results indicated that SGR extract could attenuate AGEs-induced endothelial dysfunction via RAGE-ERK1/2-NF-κB pathways. Our findings suggest that SGR extract may be beneficial for attenuating endothelial dysfunction in diabetic vascular complications.
authors: Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, Henan, Zhengzhou 450052, PR China. Electronic address: doctorsang@gmail.com.
authors: Hai-qiang
authors: HQ
authors: Sang
authors: Key Laboratory of Delivery Systems of Chinese Meteria Medica, Jiangsu Provincial Academy of Chinese Medicine, Jiangsu, Nanjing 210028, PR China; College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, PR China.
authors: Jun-fei
authors: JF
authors: Gu
authors: Key Laboratory of Delivery Systems of Chinese Meteria Medica, Jiangsu Provincial Academy of Chinese Medicine, Jiangsu, Nanjing 210028, PR China; College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing 210023, PR China.
authors: Jia-rui
authors: JR
authors: Yuan
authors: Key Laboratory of Delivery Systems of Chinese Meteria Medica, Jiangsu Provincial Academy of Chinese Medicine, Jiangsu, Nanjing 210028, PR China.
authors: Ming-hua
authors: MH
authors: Zhang
authors: Key Laboratory of Delivery Systems of Chinese Meteria Medica, Jiangsu Provincial Academy of Chinese Medicine, Jiangsu, Nanjing 210028, PR China.
authors: Xiao-bin
authors: XB
authors: Jia
authors: Key Laboratory of Delivery Systems of Chinese Meteria Medica, Jiangsu Provincial Academy of Chinese Medicine, Jiangsu, Nanjing 210028, PR China. Electronic address: wenmoxiushi@163.com.
authors: Liang
authors: L
authors: Feng
mesh_terms: D000906:Antibodies / Q000276:immunology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects; D005455:Fluorescent Antibody Technique; D017127:Glycation End Products, Advanced / Q000378:metabolism*; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000473:pathology; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D016328:NF-kappa B / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000276:immunology / Q000378:metabolism; D032281:Smilax / Q000737:chemistry*; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000906:Antibodies; D017127:Glycation End Products, Advanced; D016328:NF-kappa B; D010936:Plant Extracts; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; D013482:Superoxide Dismutase
keywords: Advanced glycation end products; Diabetic vascular complications; Endothelial dysfunction; RAGE-ERK1/2-NF-κB pathway; Smilax glabra Roxb.