title: Neutrophil chemotaxis and local expression of interleukin-10 in the tolerance of endotoxin-induced uveitis.
abstract: OBJECTIVE
  To study the mechanism of lipopolysaccharide (LPS) tolerance in a rat model of footpad injection endotoxin-induced uveitis (EIU).
  
  
  METHODS
  EIU was produced by footpad injection of 1 mg/kg LPS in male Sprague-Dawley rats. Four experiments were undertaken in this study. First, on days 3, 7, 14, 28, 56, and 84 after LPS injection, the iris-ciliary body (ICB) was isolated. LPS tolerance-associated gene expression in the ICB was determined by quantitative polymerase chain reaction. Second, the distribution of IL-10-producing cells in frozen sections of ocular tissues was analyzed by fluorescence and confocal microscopy. Third, peripheral blood neutrophil chemotaxis was determined using a fluorescent in vitro migration assay. Fourth, for in vivo neutrophil chemotaxis assay, neutrophils isolated from EIU-tolerant or control rats were transfused into green fluorescence protein (GFP) rats injected with LPS 18 hours earlier. Six hours after transfusion, the percentage of GFP-negative neutrophils in the aqueous humor was determined by flow cytometry.
  
  
  RESULTS
  IL-10 gene expression in ICB was significantly upregulated for at least 1 month. Immunohistochemical examination indicated that dendritic cells in the ICB produced IL-10. Peripheral blood neutrophil chemotaxis in EIU-tolerant rats was inhibited significantly in vitro and in vivo. IL-10 enhanced the reduction of neutrophil chemotaxis in EIU-tolerant rats in vitro.
  
  
  CONCLUSIONS
  The results suggest that continuous high expression of IL-10 in the eye and the reduction of peripheral blood neutrophil chemotaxis play significant roles in the mechanism of LPS tolerance in a rat model of footpad injection EIU.
authors.affiliation: Department of Ophthalmology, Osaka University Medical School, Osaka, Japan.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Mashimo
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Ohguro
authors.forename: Shintaro
authors.initials: S
authors.lastname: Nomura
authors.forename: Noriyasu
authors.initials: N
authors.lastname: Hashida
authors.forename: Kei
authors.initials: K
authors.lastname: Nakai
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Tano