title: Laser-induced choroidal neovascularization in mice attenuated by deficiency in the apelin-APJ system.
abstract: OBJECTIVE
  To investigate the role of the apelin-APJ system in the development of choroidal neovascularization (CNV).
  
  
  METHODS
  Experimental CNV was induced by laser photocoagulation in wild-type (WT), apelin-deficient (apelin-KO), and apelin receptor (APJ)-deficient (APJ-KO) mice. The gene expression levels of angiogenic or inflammatory factors were determined by quantitative real-time reverse transcription-polymerase chain reaction. APJ expression in CNV lesions was examined by immunohistochemistry. The sizes of the CNV lesions in the three mouse models were measured and compared histologically using isolectin B4 staining. Macrophage recruitment was measured by flow cytometric analysis. Proliferation of endothelial cells was determined using the alamar Blue assay.
  
  
  RESULTS
  Laser photocoagulation significantly increased expression of apelin and APJ in the retina-retinal pigment epithelium (RPE) complex. APJ immunoreactive cells were found in the CNV lesions and colocalized with platelet endothelial cell adhesion molecule-1, an endothelial cell marker. The sizes of the CNV lesions in apelin-KO or APJ-KO mice decreased significantly compared with those in the WT mice. Macrophages in the RPE complex of the apelin-KO mice, in which gene expression of the inflammatory factors was almost equal to that in WT mice, were recruited as a result of laser photocoagulation to the same degree as in WT mice. In addition, apelin small and interfering RNA (siRNA) suppressed proliferation of endothelial cells independently of vascular endothelial growth factor (VEGF) receptor 2 signaling, while VEGF increased expression of apelin and APJ in human umbilical vein endothelial cells.
  
  
  CONCLUSIONS
  The results suggested that the apelin-APJ system contributes to CNV development partially independent of the VEGF pathway.
authors.affiliation: Department of Ophthalmology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Hara
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kasai
authors.forename: Fumi
authors.initials: F
authors.lastname: Gomi
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Satooka
authors.forename: Susumu
authors.initials: S
authors.lastname: Sakimoto
authors.forename: Kei
authors.initials: K
authors.lastname: Nakai
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yoshioka
authors.forename: Akiko
authors.initials: A
authors.lastname: Yamamuro
authors.forename: Sadaaki
authors.initials: S
authors.lastname: Maeda
authors.forename: Kohji
authors.initials: K
authors.lastname: Nishida
mesh_terms: D054392:Adipokines; D043925:Angiogenesis Inducing Agents / Q000378:metabolism; D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D000073861:Apelin; D000075244:Apelin Receptors; D049109:Cell Proliferation; D020256:Choroidal Neovascularization / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000473:pathology; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D005786:Gene Expression Regulation / Q000502:physiology; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins / Q000502:physiology*; D017075:Laser Coagulation; D008264:Macrophages / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D043562:Receptors, G-Protein-Coupled / Q000502:physiology*; D012160:Retina / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D054392:Adipokines; D043925:Angiogenesis Inducing Agents; D000943:Antigens, Differentiation; D000073861:Apelin; D000075244:Apelin Receptors; C402826:Apln protein, mouse; C491285:Aplnr protein, mouse; D016207:Cytokines; D018836:Inflammation Mediators; D036341:Intercellular Signaling Peptides and Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D043562:Receptors, G-Protein-Coupled; D042461:Vascular Endothelial Growth Factor A; C036763:monocyte-macrophage differentiation antigen; C467480:vascular endothelial growth factor A, mouse
keywords: APJ; age-related macular degeneration; apelin; choroidal neovascularization; vascular endothelial growth factor