title: Intravenously administered anti-recoverin antibody alone does not pass through the blood-retinal barrier.
abstract: OBJECTIVE
  Cancer-associated retinopathy is a paraneoplastic retinal degeneration which may primarily result from auto-immune mediated apoptosis. It has been hypothesized that high titer of auto-antibodies are able to cross the blood-retinal barrier (BRB) and to enter retinal cells to activate apoptotic pathway which has been already well-established. However, it still remains to be elucidated whether auto-antibodies could cross BRB in the retina. Herein, we demonstrated that intravenously administrated anti-recoverin antibodies could not pass through BRB and not lead to retinal cell death.
  
  
  METHODS
  Anti-recoverin antibody was intravenously injected to C57BL/6 mice, which were sacrificed 1 and 7 days to obtain eye. Vascular endothelial growth factor was intravitreally injected to induce BRB breakdown, which was confirmed by fluorescein angiography and western blotting for zonula occludens (ZO)-1, ZO-2 and occludin. To investigate the location of anti-recoverin antibody in the retina, immunofluorescein was performed. The retinal toxicity of intravenous anti-recoverin antibody was evaluated by histological examination and transferase-mediated dUTP nick-end labeling. Immunofluorescein staining for glial fibrillary acidic protein was done to address glial activation as well.
  
  
  RESULTS
  Intravenously administrated anti-recoverin antibodies were exclusively distributed on retinal vessels which were co-localized with CD31, and led to neither increase of glial fibrillary acidic protein expression, as an indicator of retinal stress, nor apoptotic retinal cell death. Moreover, even in the condition of vascular endothelial growth factor-induced BRB breakdown, anti-recoverin antibodies could not migrate across BRB and still remained on retinal vessels without retinal cytotoxicity.
  
  
  CONCLUSIONS
  Our results suggest that high titer of intravascular anti-recoverin antibodies could not penetrate into the retina by themselves, and BRB breakdown mediated by dysregulation of tight junction might not be sufficient to allow anti-recoverin antibodies to pass through BRB.
authors.affiliation: Fight against Angiogenesis-Related Blindness Laboratory, Department of Ophthalmology, Seoul National University College of Medicine & Seoul Artificial Eye Center, Clinical Research Institute, Seoul National University Hospital, Seoul, Korea.
authors.forename: Jeong Hun
authors.initials: JH
authors.lastname: Kim
authors.forename: Jin Hyoung
authors.initials: JH
authors.lastname: Kim
authors.forename: Dong Hun
authors.initials: DH
authors.lastname: Kim
authors.forename: Woong-Yang
authors.initials: WY
authors.lastname: Park
authors.forename: Kyu-Won
authors.initials: KW
authors.lastname: Kim
authors.forename: Young Suk
authors.initials: YS
authors.lastname: Yu
mesh_terms: D000818:Animals; D000906:Antibodies / Q000008:administration & dosage* / Q000378:metabolism*; D001813:Blood-Retinal Barrier / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D005260:Female; D007275:Injections, Intravenous; D051379:Mice; D008810:Mice, Inbred C57BL; D051603:Recoverin / Q000276:immunology*; D012160:Retina / Q000166:cytology / Q000187:drug effects; D012171:Retinal Vessels / Q000378:metabolism
chemical_list: D000906:Antibodies; D051603:Recoverin