title: Chemical injury-induced corneal opacity and neovascularization reduced by rapamycin via TGF-β1/ERK pathways regulation.
abstract: OBJECTIVE
  To investigate the protective effect of rapamycin against alkali burn-induced corneal damage in mice.
  
  
  METHODS
  BALB/c mice were treated with 0.1 N NaOH to the cornea for 30 seconds. Corneal neovascularization and opacity were clinically evaluated at 1, 2, and 4 weeks after chemical burn injury. Rapamycin was delivered topically to right eyes (1 mg/mL) and injected intraperitoneally (0.2 mg/kg) once a day. Concentrations of interleukin-6 (IL-6) and transforming growth factor-beta1 (TGF-β1) in the cornea were measured by enzyme-linked immunosorbent assay (ELISA). In vitro-cultured human corneal stromal cells were treated with 0 to 500 nM rapamycin for 3 days and then assessed by immunofluorescence staining of vimentin and alpha-smooth muscle actin (α-SMA). Western blotting assays for α-SMA, phosphorylated extracellular signal-regulated kinase (ρ-ERK 1/2), and total ERK 1/2 were also performed.
  
  
  RESULTS
  Corneal neovascularization and corneal opacity scores measured 4 weeks after the chemical burn corneal injury were lower in the rapamycin group than in the control group. Two weeks after the chemical burn injury, a significant elevation in the corneal IL-6 levels of the positive control group was observed, compared to the levels in the negative control group or the rapamycin group (P < 0.05). Corneal TGF-β1 levels were lower in the rapamycin-treated group than in the control group at 4 weeks after chemical burn injury (P < 0.05). Moreover, rapamycin inhibited TGF-β1-induced α-SMA expression and augmented ERK 1/2 phosphorylation.
  
  
  CONCLUSIONS
  Rapamycin treatment reduced corneal opacity and corneal neovascularization in BALB/c mice. Rapamycin protected the cornea from chemical damage via reduction of IL-6 and TGF-β1 expression. Rapamycin reduced α-SMA expression through the ERK 1/2 pathway.
authors.affiliation: Department of Ophthalmology, Hallym University College of Medicine, Seoul, Republic of Korea. schinn@hanmail.net
authors.forename: Young Joo
authors.initials: YJ
authors.lastname: Shin
authors.forename: Joon Young
authors.initials: JY
authors.lastname: Hyon
authors.forename: Won Seok
authors.initials: WS
authors.lastname: Choi
authors.forename: Kayoung
authors.initials: K
authors.lastname: Yi
authors.forename: Eui-Sang
authors.initials: ES
authors.lastname: Chung
authors.forename: Tae-Young
authors.initials: TY
authors.lastname: Chung
authors.forename: Won Ryang
authors.initials: WR
authors.lastname: Wee
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002057:Burns, Chemical / Q000150:complications / Q000188:drug therapy; D002478:Cells, Cultured; D016510:Corneal Neovascularization / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism; D003318:Corneal Opacity / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism; D003319:Corneal Stroma / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D005126:Eye Burns / Q000150:complications / Q000188:drug therapy; D007166:Immunosuppressive Agents / Q000494:pharmacology / Q000627:therapeutic use*; D007274:Injections, Intraperitoneal; D015850:Interleukin-6 / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D015398:Signal Transduction / Q000187:drug effects*; D020123:Sirolimus / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D007166:Immunosuppressive Agents; D015850:Interleukin-6; D020123:Sirolimus
keywords: alpha-smooth muscle actin; chemical burn; corneal stromal cell; extracellular signal-regulated kinase; interleukin-6; rapamycin; transforming growth factor-beta1