Construction of a plasmid for screening in vivo gene expression and characteristic of immune response in infective endocarditis
Date Issued
2005
Date
2005
Author(s)
Wu, Shu-Hui
DOI
zh-TW
Abstract
Streptococcus mutans, a member of the viridans streptococci, can cause dental caries in the oral cavity and infective endocarditis (IE) when entering into blood circulation. Major processes in the pathogenesis of IE are the formation of vegetations at the damaged surface on valves and inflammation of the endocardium. In the first part of this study, we developed a novel plasmid, pDLDlacZ for in vivo expression technology (IVET) in order to identify novel virulent factors of S. mutans. A Streptococcus-E. coli shuttle vector which carries dual (Km-lac) promoterless reporter genes has been constructed.
In the secondary part of the study, we used an experimental endocarditis rat model established previously in our laboratory to investigate the immune response induced by S. mutans. Human biopsies of infective endocarditis at chronic inflammatory stage was also analyzed and compared with the immune response identified on experimental endocarditis. Nests of S. mutans, with positive staining for secretory proteins, was walled-off in the fibrosis region of VG to avoid phagocytosis. Immunohistochemistry staining of the tissue sections showed that NF-κB was activated in both macrophage and fibroblast 24 hours after infection. In human biopsies, IL-6, TNF-α, and IL-1β secretion was found in macrophages, fibroblasts, and endothelium in addition to activated NF-κB. Therefore, NF-κB activation in the fibroblasts in endocardium might play an impartment role in the persistence of inflammation in IE
Subjects
轉糖鏈球菌
S. mutans
IVET
NF-kappa B
Type
other
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