1998 Fiscal Year Final Research Report Summary
Mechanisms of suppression on cytokine expression in HTLV-1-infected T cell clones by aqueous humor
| Project/Area Number |
09671825
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Ophthalmology
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| Research Institution | Kurume University |
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Principal Investigator |
YOSHIMURA Koichi Kurume University, Ophthalmology, Lecturer, 医学部, 講師 (30240352)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Toshiki University of Tokyo, Pathology, Associate Professor, 医科学研究所, 助教授 (30182934)
HIKITA Naofumi Kurume University, Ophthalmology, Associate Professor, 医学部, 助教授 (80173152)
MOCHIZUKI Manabu Tokyo Medical and Dental University, Ophthalmology, Professor, 医学部, 教授 (10010464)
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| Project Period (FY) |
1997 – 1998
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| Keywords | HTLV-1 / uveitis / aqueous humor / cytokine / suppressive factor / sFasL |
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| Research Abstract |
In spite of constitutive overexpression of inflammatory cytokines in HTLV-1-infected T-cells, most cytokine genes are not expressed in the fresh infiltrating cells in the eye, suggesting a suppression of cytokine gene expression. To understand pathophysiology of HU, we characterized the suppressive factors in the aqueous humor (AH) and the mechanisms of suppression. AH dose-dependently suppressed the production of IFN-gamma and IL-6 by HTLV-l-infected T-cell clones and a cell line, Sez. Fractionation of AH by gel filtration column revealed four peaks of suppressive activity, which apparently corresponded molecular masses of a-MSH, VIP, MIF and TGF-beta. However, TGF-beta2, a major immunosuppressive factor in AH, did not show any suppressive activity. We demonstrated sFasL in AH by ELISA using NOKl and NOK3 anti-FasL mAbs and revealed neutralization of the suppression by NOK2 mAb. Crosslinking Fas selectively repressed the IFN-gamma mRNA expression. His-tagged sFasL showed dose-dependent suppression of IFN-gamma production and promoter activity in transient Luciferase assay. Suppression was evident at the concentration as low as 10 to l00pg/ml. Deletion and mutation analyses of IFN-gamma promoter identified a responsive element of 24 nucleotides to the Fas-mediated suppression, which contained binding motifs of YYl and an B-box. Mutation of the E-box in this element abrogated the suppression. Suppression was abolished by expression of dominant negative form of Daxx, an adaptor protein of Fas. The results indicated that sFasL is one of the suppressive factors of cytokine production in the eye, which would play a protective role against cytokine-mediated tissue damages. They also suggested a distinct function of sFasL from the membrane-bound from of FasL.
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Research Products
(15 results)
