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A. Yoshida, K. Ohta, T. Murata, T. Kikuchi; Protective Role of Heat Shock Protein 70 Against Endotoxin–Induced Uveitis in Rats . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4523.
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© ARVO (1962-2015); The Authors (2016-present)
Heat shock protein 70 ( HSP70 ) is one of the best–kown endogenous factors protecting cell and tissue injuries under various pathologic conditions. We previously reported that m–RNA expression and protein of HSP70 increased in the iris–ciliary body ( ICB ) at early stage of endotoxin–induced uveitis ( EIU ). On the other hand,Geranylgeranylacetone ( GGA ) is an acyclic polyisoprenoid and has been reported to induce HSP70 in rat gastric mucosa and other cells. The purpose of this study is to determine whether GGA induces HSP70 in the ICB, and to evaluate the protective effect of HSP70 against ocular inflammation.
Male Lewis rats ( 6 – 7 weeks old, 150 – 200 g ) were given by oral administration of GGA ( 200mg / kg ). After 24 hours of GGA pretreatment, EIU was induced by a footpad injection of 100µg lipopolysaccharide ( LPS ). Aqueous humor ( AqH ) was collected from the anterior chamber at 24 hours after LPS injection, leukocytes were counted by phase–contrast microscopy and the total protein concentration was measured using the bicinchoninic acid protein assay reagent kit ( Pierce, Rockford, IL, USA ). Western blot analysis and immunohistochemical study for HSP70 in ICB were performed.
There were increased expression of HSP70 in ICB at 24 hours after administration of GGA. The number of infiltrating cells and the concentration of protein in the AqH was significantly elevated by LPS injection, and GGA significantly reduced the number of cells and the protein concentration. Thus, the number of infiltrating cells was 2590 ±472 cells / µl in the untreated rats, and pretreatment with GGA results in significant reduction to 104 ±19.9 cells /µl. The protein concentration in AqH was 10.8 ± 0.05 mg / ml and 31 ± 10.3 mg/ ml respectively.
The results of present study were that an intragastric injection of GGA induced HSP70 expression in the rat ICB, that pretreatment with GGA attenuated both the number of infiltrating cells and protein concentration of AqH. Our results suggest that HSP70 may play a protective role against LPS–induced ocular inflammation. In addition, enough dose of GGA may potentially reduce the ocular inflammation induced by LPS.
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