HASHIMOTO Hiroshi Juntendo Univ.School of Med., Professor, 医学部, 教授 (60053120)
TAKASAKI Yoshinari Juntendo Univ.School of Med., Associate Professor, 医学部, 助教授 (80154772)
SEKIGAWA Iwao Juntendo Univ.School of Med., Assistant Professor, 医学部, 講師 (80179332)
|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1996 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1995 : ¥1,300,000 (Direct Cost : ¥1,300,000)
To prove more directly the possibility that human endogenous retroviruses (HERV) play a role as a pathogen in human autoimmune diseases, we tested the expression of HERV gene products using their own proteins and gene. Clone 4-1, most provably expressed HERV was used because its nucleotide sequences conserved well as retroviruses.
Antibodies to recombinant p30gag derived from clone 4-1 were found in 48% of SLE,35% of MCTD,and 30% of Sjogren's syndrome according Western immunoblotting analysis. Clone 4-1 derived p30gag detected more freuently anti-p30gag antibody in human autoimmune diseases, as compared to antibodies detected with synthetic peptides based on HERV and other species of retroviruses including human infectious retrovirus, HIV-1 and HTLV-I.This indicated that clone 4-1 or closely related virus may express in these diseases. Further, antibodies to clone 4-1 env were found in 10% of SLE,and Sjogren's syndrome, and 20% of MCTD,despite relatively low frequency comparing to that
of p30gag. Of interest is that anti-env antibody positive serum has always anti-p30gag antibody. Since results of absorption test using env and p30gag protein indicated that these results was due to no cross-reactivity, there is the possibility that clone 4-1 may express as viral particles in some patients. In addition, we reported a lupus patient with intersitial pneumonitis whose bronchoalveoral lavage fluid had syncytial cells well characterized in retroviral infection. Intensive study by measuring RT activitly and electron microscopy suggested the contribution of unknown retrovirus. In addition, serum from this patient strongly reacted with clone 4-1 p30gag, suggesting that this virus appeared to be HERV.mRNA transcribed from clone 4-1 gag or env region was detected in peripheral blood lymphocytes from some SLE patients using RT-PCR.Since these data indicated clone 4-1 is actively expressed in human autoimmune diseases, we next examined function of clone 4-1 LTR using luciferase assay. About 50bp nucleotide element in LTR revealed promoter activity. However, no clone 4-1 expression was detected in normal tissues except placentas. This evidence suggested us to the assumption that activation of clone 4-1 whole LTR required some stimulations. Although whole LTR function was tested in the presence of several cytokines, such as IL6, IL1 beta, TNF-alpha, sex steroid hormones and hCG,no promoter function was activated using above assay system.
Further study concerning on the analysis of LTR function and HERV protein induced autoimmunity will be required for elucidation of pathogenesis in human autoimmune diseases. Less