title: Anti-inflammatory recombinant TSG-6 stabilizes the progression of focal retinal degeneration in a murine model.
abstract: BACKGROUND
  Inflammatory responses are detected in the retina of patients with age-related macular degeneration and Ccl2-/-/Cx3cr1-/- mice on rd8 background,(Ccl2-/-/Cx3cr1-/- mice) a model that develops progressive age-related macular degeneration-like retinal lesions including focal photoreceptor degeneration, abnormal retinal pigment epithelium and A2E accumulation. Tumor necrosis factor-inducible gene 6 protein is an anti-inflammatory protein and has been shown to improve myocardial infarction outcome and chemically injured cornea in mice by suppressing inflammation. In this study, we evaluated the effect of an intravitreous injection of recombinant TSG-6 on the retinal lesions of Ccl2-/-/Cx3cr1-/- mice.
  
  
  METHODS
  Recombinant TSG-6 (400 ng) was administered by intravitreous injection into the right eye of six-week-old Ccl2-/-/Cx3cr1-/- mice. Their left eye was injected with phosphate-buffered saline as a control. Funduscopic pictures were taken before injection and sequentially once a month after injection. The mice were killed two months after injection and the ocular histology examined. Retinal A2E, a major component of lipofuscin, was measured by high performance liquid chromatography. The microarray of ocular mRNA of 92 immunological genes was performed. The genes showing differentiated expression in microarray were further compared between the injected right eye and the contralateral (control) eye by [real-time quantitative reverse transcription polymerase chain reaction] qRT-PCR.
  
  
  RESULTS
  The continuous monitoring of the fundus for two months showed a slower progression or alleviation of retinal lesions in the treated right eyes as compared with the untreated left eyes. Among 23 pairs of eyes, the lesion levels improved in 78.3%, stayed the same in 8.7% and progressed in 13.0%. Histology confirmed the clinical observation. Even though there was no difference in the level of A2E between the treated and the untreated eyes, microarray analysis of 92 immune genes showed that IL-17a was substantially decreased after the treatment. Expression of TNF-α showed a similar pattern to IL-17a. The results were consistent in duplicated arrays and confirmed by qRT-PCR.
  
  
  CONCLUSIONS
  We concluded that intravitreous administration of recombinant TSG-6 might stabilize retinal lesions in Ccl2-/-/Cx3cr1-/- mice on rd8 background. Modulation of ocular immunological gene expressions, especially IL-17a, could be one of the mechanisms.
authors.affiliation: Laboratory of Immunology, National Eye Institute, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Jingsheng
authors.initials: J
authors.lastname: Tuo
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Cao
authors.forename: Defen
authors.initials: D
authors.lastname: Shen
authors.forename: Yujuan
authors.initials: Y
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Joo Youn
authors.initials: JY
authors.lastname: Oh
authors.forename: Darwin J
authors.initials: DJ
authors.lastname: Prockop
authors.forename: Chi-Chao
authors.initials: CC
authors.lastname: Chan
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage*; D000073883:CX3C Chemokine Receptor 1; D015815:Cell Adhesion Molecules / Q000008:administration & dosage*; D018932:Chemokine CCL2 / Q000172:deficiency; D004195:Disease Models, Animal; D018450:Disease Progression; D015870:Gene Expression / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D020381:Interleukin-17 / Q000378:metabolism; D058449:Intravitreal Injections; D008062:Lipofuscin / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D046529:Microscopy, Electron, Transmission; D016253:Microscopy, Immunoelectron; D019721:Ophthalmoscopes; D019707:Receptors, Chemokine / Q000172:deficiency; D012160:Retina / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D012162:Retinal Degeneration / Q000188:drug therapy* / Q000473:pathology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000893:Anti-Inflammatory Agents; D000073883:CX3C Chemokine Receptor 1; C491768:Ccl2 protein, mouse; D015815:Cell Adhesion Molecules; D018932:Chemokine CCL2; C471885:Cx3cr1 protein, mouse; D020381:Interleukin-17; D008062:Lipofuscin; D019707:Receptors, Chemokine; C072273:TNFAIP6 protein, human; D014409:Tumor Necrosis Factor-alpha