title: Tumor necrosis factor-alpha mediates photoreceptor death in a rodent model of retinal detachment.
abstract: OBJECTIVE
  Photoreceptor degeneration is a major cause of visual loss in various retinal diseases, including retinal detachment (RD) and neovascular AMD, but the underlying mechanisms remain elusive. In this study, the role of TNFα in RD-induced photoreceptor degeneration was investigated.
  
  
  METHODS
  RD was induced by subretinal injection of hyaluronic acid. Photoreceptor degeneration was assessed by counting the number of apoptotic cells with TdT-dUTP terminal nick-end labeling (TUNEL) 3 days after RD and measurement of the outer nuclear layer (ONL) thickness 7 days after RD. As the target of anti-inflammatory treatment, the expression of TNFα, with or without dexamethasone (DEX) was examined in rats by real-time PCR. To understand the role of TNFα in photoreceptor degeneration, RD was induced in mice deficient in TNFα or its receptors (TNFR1, TNFR2, and TNFR1 and -2), or in wild-type (WT) mice by using a functionally blocking antibody to TNFα. CD11b(+) cells in the outer plexiform layer (OPL) and subretinal space were counted by immunohistochemistry (IHC).
  
  
  RESULTS
  Treatment with DEX (P = 0.001) significantly suppressed RD-induced photoreceptor degeneration and the expression of TNFα. RD-induced photoreceptor degeneration was significantly suppressed with specific blockade of TNFα (P = 0.032), in mice deficient for TNFα (P < 0.001), TNFR2 (P = 0.001), or TNFR1 and -2 (P < 0.001). However, lack of TNFR1 did not protect against RD-induced photoreceptor degeneration (P = 0.060). Müller cell activation was unchanged in WT and TNFα(-/-) mice. Recruitment of CD11b(+) monocytes was significantly lower in the TNFα(-/-) mice compared to WT mice (P = 0.002).
  
  
  CONCLUSIONS
  TNFα plays a critical role in RD-induced photoreceptor degeneration. This pathway may become an important target in the prevention of RD-induced photoreceptor degeneration.
authors.affiliation: Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan. ntoru@oph.med.tohoku.ac.jp
authors.forename: Toru
authors.initials: T
authors.lastname: Nakazawa
authors.forename: Maki
authors.initials: M
authors.lastname: Kayama
authors.forename: Morin
authors.initials: M
authors.lastname: Ryu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kunikata
authors.forename: Ryou
authors.initials: R
authors.lastname: Watanabe
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yasuda
authors.forename: Jiro
authors.initials: J
authors.lastname: Kinugawa
authors.forename: Demetrios
authors.initials: D
authors.lastname: Vavvas
authors.forename: Joan W
authors.initials: JW
authors.lastname: Miller
mesh_terms: D000818:Animals; D019138:Antibodies, Blocking / Q000008:administration & dosage; D017209:Apoptosis; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D004195:Disease Models, Animal; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects / Q000473:pathology*; D051381:Rats; D011914:Rats, Inbred BN; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000502:physiology; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000502:physiology; D012162:Retinal Degeneration / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D012163:Retinal Detachment / Q000378:metabolism / Q000473:pathology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology / Q000502:physiology*
chemical_list: D019138:Antibodies, Blocking; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; C506236:Tnfrsf1a protein, mouse; D014409:Tumor Necrosis Factor-alpha; D003907:Dexamethasone