2005 Fiscal Year Final Research Report Summary
Molecular mechanisms of apoptotic pathway in the pathogenesis of bleomycin-induced scleroderma
| Project/Area Number |
16591090
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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 |
Dermatology
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| Research Institution | Tokyo Medical and Dental University |
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Principal Investigator |
YAMAMOTO Toshiyuki Tokyo Medical and Dental University, Department of Dermatology, Part-time lecturer, 医学部附属病院, 非常勤講師 (30242192)
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| Project Period (FY) |
2004 – 2005
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| Keywords | scleroderma / animal model / bleomycin / apoptosis / fibrosis |
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| Research Abstract |
To elucidate the role of apoptosis in scleroderma, we examined the induction of apoptosis and expression of Fas, Fas ligand (FasL), as well as caspase-3 in a murine model of bleomycin-induced scleroderma. Effect of systemic in vivo neutralization of FasL on the development of scleroderma was also investigated. Dermal sclerosis was induced by repeated local injections of bleomycin (1mg/mL) in C3H/HeJ mice. Induction of apoptosis was examined by TUNEL assay and DNA gel electrophoresis. TUNEL positivity was prominently detected on keratinocytes and infiltrating mononuclear cells, but not endothelial cells and fibroblasts, in the lesional skin following bleomycin treatment. DNA fragmentation revealed laddering at 3 to 4 week following bleomycin treatment. Immunohistochemistry showed increased expression of Fas in infiltrating mononuclear cells at early phase following bleomycin exposure, whereas constitutive expression in fibroblasts. FasL expression was increased in mononuclear cells as w
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ell as fibroblasts in the sclerotic skin. Results of RT-PCR analysis revealed that expression of FasL mRNA was upregulated and reached a maximum at 3 week, whereas Fas mRNA was continuously detected. mRNA expression as well as activity of caspase-3 was also enhanced at 3 week after bleomycin treatment. Administration of neutralizing anti- FasL antibody together with local bleomycin treatment reduced the development of dermal sclerosis, in association with the reduction of TUNEL-positive mononuclear cells infiltrating in the dermis and aso with the blockade of apoptosis. To further investigate the role of Fas/FasL pathway in the oathogenesis of scleroderma, we examined whether the induction of dermal sclerosis is suppressed in Fas-deficient (lpr) and Fasl-deficient (gld) mice. Results of histological examination showed that the induction of dermal sclerosis was significantly suppressed in both lpr and gld mice by bleomycin treatment. Collagen contents in the skin and TUNEL-positive infiltrating cells were significantly reduced in both lpr and gld mice, as compared with wild-type. These findings suggest that Fas/FasL pathway is an important contributor involved in the pathophysiology of bleomycin-induced scleroderma. Less
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