title: Vascular endothelial growth factor-C secretion is increased by advanced glycation end-products: possible implication in ocular neovascularization.
abstract: OBJECTIVE
  Neovascularization is a common complication of many degenerative and vascular diseases of the retina. Advanced glycation end-products (AGEs) have a pathologic role in the development of retinal neovascularization, mainly for their ability in upregulating vascular endothelial growth factor-A (VEGF-A) secretion. The aim of this study was to investigate whether AGEs are able to modulate the secretion of VEGF-C, another angiogenic factor that increases the effect of VEGF-A.
  
  
  METHODS
  A human retinal pigment epithelial cell line (ARPE-19) and human endothelial vascular cell line (HECV) cells were cultured for 24 h in presence of AGEs, and then mRNA expression of VEGF-C was analyzed with reverse transcription-polymerase chain reaction (RT-PCR). To verify whether AGEs-induced VEGF secretion is mediated by RAGE (Receptor for AGEs), RAGE expression was depleted using the small interfering RNA method. To investigate whether VEGF-A is involved in upregulating VEGF-C secretion, the cells were cultured for 24 h in the presence of bevacizumab, a monoclonal antibody against VEGF-A, alone or in combination with AGEs. VEGF-A and VEGF-C levels in the supernatants of the treated cells were evaluated with enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Exposure to AGEs significantly increased VEGF-C gene expression in ARPE-19 cells. AGEs-induced VEGF-C secretion was upregulated in retinal pigment epithelium (RPE) and endothelial cells. Downregulation of RAGE expression decreased VEGF-A secretion in cell models, and increased VEGF-C secretion in ARPE-19 cells. Adding bevacizumab to the culture medium upregulated constitutive VEGF-C secretion but did not affect AGEs-induced VEGF-C secretion.
  
  
  CONCLUSIONS
  These findings suggest that AGEs take part in the onset of retinal neovascularization, not only by modulating VEGF-A but also by increasing VEGF-C secretion. In addition, our results suggest that VEGF-C may compensate for treatments that reduce VEGF-A.
authors.affiliation: Department of Internal Medicine and Medical Specialties, Viale Benedetto, Genova, Italy. alep100@hotmail.com
authors.forename: Alessandra
authors.initials: A
authors.lastname: Puddu
authors.forename: Roberta
authors.initials: R
authors.lastname: Sanguineti
authors.forename: Arianna
authors.initials: A
authors.lastname: Durante
authors.forename: Massimo
authors.initials: M
authors.lastname: Nicolò
authors.forename: Giorgio L
authors.initials: GL
authors.lastname: Viviani
mesh_terms: D061067:Antibodies, Monoclonal, Humanized / Q000494:pharmacology; D000068258:Bevacizumab; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D017127:Glycation End Products, Advanced / Q000494:pharmacology*; D006801:Humans; D009389:Neovascularization, Pathologic; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000235:genetics; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000037:antagonists & inhibitors* / Q000235:genetics; D055213:Retinal Pigment Epithelium / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors / Q000235:genetics; D042582:Vascular Endothelial Growth Factor C / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: D061067:Antibodies, Monoclonal, Humanized; D017127:Glycation End Products, Advanced; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042582:Vascular Endothelial Growth Factor C; D000068258:Bevacizumab