title: Novel application of low pH-dependent fluorescent dyes to examine colitis.
abstract: BACKGROUND
  Endoscopy capable of fluorescence observation provides histological information on gastrointestinal lesions. We explored the novel application of low pH-dependent fluorescent dyes for fluorescence observation of crypt structure and inflammatory cell infiltration in the colon.
  
  
  METHODS
  Low pH-dependent fluorescent dyes were applied to the colonic mucosa of normal mice for observation under fluorescence stereomicroscopy system. We also examined mouse models of colitis, which were induced by trinitrobenzenesulfonic acid, dextran sulfate sodium or interleukin-10 deficiency.
  
  
  RESULTS
  Topical application of low pH-dependent fluorescent dyes revealed crypts as ring-shaped fluorescent stains by visualizing the mucin granules of goblet cells. Because of the minimal fluorescence intensity of the low pH-dependent fluorescent dyes in phosphate-buffered saline, it was not necessary to wash the mucosa before the fluorescence observation. 4-Nitro-7-piperazino-2,1,3-benzoxadiazole (NBD-PZ) was quicker to achieve complete staining (three minutes) than LysoSensor Green DND-153 and DND-189 (20 minutes). In each type of colitis, NBD-PZ revealed the destruction of the crypts as the disappearance of the ring-shaped fluorescent stains and the infiltration of inflammatory cells as the aggregation of punctate fluorescent stains through visualization of lysosomes.
  
  
  CONCLUSIONS
  Low pH-dependent fluorescent dyes, especially NBD-PZ, are suitable for topical application to the colonic mucosa and have characteristics that allow for the histological examination of colitis.
authors.affiliation: Molecular Biology and Pathogenesis of Gastroenterology, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, Aichi 466-8550, Japan. kio@med.nagoya-u.ac.jp
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ishiguro
authors.forename: Takafumi
authors.initials: T
authors.lastname: Ando
authors.forename: Osamu
authors.initials: O
authors.lastname: Watanabe
authors.forename: Hidemi
authors.initials: H
authors.lastname: Goto
mesh_terms: D000285:Administration, Rectal; D000818:Animals; D003092:Colitis / Q000188:drug therapy / Q000473:pathology*; D005456:Fluorescent Dyes / Q000008:administration & dosage / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D016753:Interleukin-10 / Q000172:deficiency; D007413:Intestinal Mucosa / Q000473:pathology*; D007963:Leukocytes, Mononuclear / Q000378:metabolism / Q000473:pathology; D018942:Macrolides / Q000627:therapeutic use; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D010069:Oxadiazoles / Q000008:administration & dosage / Q000032:analysis*; D010879:Piperazines / Q000008:administration & dosage / Q000032:analysis*; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors
chemical_list: C432126:4-nitro-7-piperazino-2,1,3-benzoxadiazole; D005456:Fluorescent Dyes; D018942:Macrolides; D010069:Oxadiazoles; D010879:Piperazines; D016753:Interleukin-10; C040929:bafilomycin A1; D006180:Proton-Translocating ATPases