title: Placental growth factor enhances angiogenesis in human intestinal microvascular endothelial cells via PI3K/Akt pathway: Potential implications of inflammation bowel disease.
abstract: BACKGROUND
  Angiogenesis plays a major role in the pathogenesis of inflammatory bowel disease (IBD). Placental growth factor (PlGF) is a specific regulator of pathological angiogenesis and is upregulated in the sera of IBD patients. Therefore, the role of PlGF in IBD angiogenesis was investigated here using HIMECs.
  
  
  METHODS
  The expression of PlGF and its receptors in human intestinal microvascular endothelial cells (HIMECs) and inflamed mucosa of IBD patients were examined using quantitative PCR and western blot analysis and the role of PlGF in IBD HIMECs was further explored using small interfering RNA (siRNA). The induction of pro-inflammatory cytokine by PlGF in HIMECs was confirmed by ELISA. The capacity of PlGF to induce angiogenesis in HIMECs was tested through proliferation, cell-migration, matrigel tubule-formation assays and its underlying signaling pathway were explored by western blot analysis of ERK1/2 and PI3K/Akt phosphorylation.
  
  
  RESULTS
  mRNA and protein expression of PlGF and its receptor NRP-1 were significantly increased in IBD HIMECs. Inflamed mucosa of IBD patients also displayed higher expression of PIGF. The production of IL-6 and TNF-α in culture supernatant of HIMECs treated with exogenous recombinant human PlGF-1 (rhPlGF-1) were increased. Furthermore, rhPlGF-1 significantly induced HIMECs migration and tube formation in a dose-dependent manner and knockdown of endogenous PlGF in IBD HIMECs using siRNA substantially reduced these angiogenesis activities. PlGF induced PI3K/Akt phosphorylation in HIMECs and pretreatment of PlGF-stimulated HIMECs with PI3K inhibitor (LY294002) significantly inhibited the PlGF-induced cell migration and tube formation.
  
  
  CONCLUSIONS
  Our results demonstrated the pro-inflammatory and angiogenic effects of PlGF on HIMECs in IBD through activation of PI3K/Akt signaling pathway. PlGF/PI3K/Akt signaling may serve as a potential therapeutic target for IBD.
authors.affiliation: Department of Gastroenterology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Xuhui District, Shanghai 200032, China. Electronic address: mondayzy@126.com.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Gastroenterology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Xuhui District, Shanghai 200032, China. Electronic address: tu.chuantao@zs-hospital.sh.cn.
authors.forename: Chuantao
authors.initials: C
authors.lastname: Tu
authors.affiliation: Department of Gastroenterology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Xuhui District, Shanghai 200032, China. Electronic address: zhao.yuan@zs-hospital.sh.cn.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Gastroenterology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Xuhui District, Shanghai 200032, China. Electronic address: liuhch@aliyun.com.
authors.forename: Hongchun
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Gastroenterology, Zhongshan Hospital, Fudan University, 180 Fenglin Road, Xuhui District, Shanghai 200032, China. Electronic address: zhang.shuncai@zs-hospital.sh.cn.
authors.forename: Shuncai
authors.initials: S
authors.lastname: Zhang
mesh_terms: D002478:Cells, Cultured; D042783:Endothelial Cells / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000378:metabolism* / Q000473:pathology; D007422:Intestines / Q000098:blood supply / Q000503:physiopathology*; D055806:Microvessels / Q000473:pathology / Q000503:physiopathology*; D009389:Neovascularization, Pathologic / Q000473:pathology / Q000503:physiopathology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000072483:Placenta Growth Factor; D011257:Pregnancy Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction
chemical_list: C000608036:PGF protein, human; D011257:Pregnancy Proteins; D000072483:Placenta Growth Factor; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt
keywords: Angiogenesis; HIMECs; Inflammatory bowel disease; PI3K/Akt pathway; PlGF