Affiliation:
1. Department of Forensic Medicine
2. Graduate Institute of Microbiology, College of Medicine, National Taiwan University
3. Department of Oral Diagnosis and Pathology, National Taiwan University Hospital
4. National Health Research Institute, Taipei, Taiwan, Republic of China
Abstract
ABSTRACT
The glucosyltransferases (GTFs) of viridans streptococci, common pathogens of infective endocarditis, are extracellular proteins that convert sucrose into exopolysaccharides and glucans. GTFs B, C, and D of
Streptococcus mutans
are modulins that induce, in vitro and in vivo, the production of cytokines, in particular interleukin-6 (IL-6), from monocytes. The roles of
S. mutans
GTFs in infectivity and inflammation in situ were tested in a rat experimental model of endocarditis. No significant differences in infectivity, in terms of 95% infective dose and densities of bacteria inside vegetations, were observed between laboratory strain GS-5 and two clinical isolates or isogenic mutant NHS1DD, defective in the expression of GTFs. In aortic valves and surrounding tissues, IL-6 was detected by Western blots and immunostaining 24 h after GS-5 infection, was maintained over 72 h, and was followed by production of tumor necrosis factor alpha but not IL-1β. Animals infected with NHS1DD showed markedly lower levels of IL-6 (less than 5% of that of parental GS-5-infected rats), while tumor necrosis factor alpha was unaffected. In contrast, animals infected with NHR1DD, another isogenic mutant expressing only GtfB, showed a much smaller reduction (down to 56%). These results suggest that GTFs are specific modulins that act during acute inflammation, inducing IL-6 from endothelial cells surrounding the infected valves without affecting bacterial colonization in vegetations, and that IL-6 might persist in chronic inflammation in endocarditis.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Reference46 articles.
1. Ajdic, D., W. M. McShan, R. E. McLaughlin, G. Savic, J. Chang, M. B. Carson, C. Primeaux, R. Tian, S. Kenton, H. Jia, S. Lin, Y. Qian, S. Li, H. Zhu, F. Najar, H. Lai, J. White, B. A. Roe, and J. J. Ferretti. 2002. Genome sequence of Streptococcus mutans UA159, a cariogenic dental pathogen. Proc. Natl. Acad. Sci. USA99:14434-14439.
2. Alter, P., J. Hoeschen, M. Ritter, and B. Maisch. 2002. Usefulness of cytokines interleukin-6 and interleukin-2R concentrations in diagnosing active infective endocarditis involving native valves. Am. J. Cardiol.89:1400-1404.
3. Cloning of a Streptococcus mutans glucosyltransferase gene coding for insoluble glucan synthesis
4. Bayer, A. S., and W. M. Scheld. 2000. Endocarditis and intravascular infections, p. 857-902. In G. L. Mandell, J. E. Bennett, and M. Dolin (ed.), Mandell, Douglas, and Bennett's principles and practices of infectious diseases, 5th ed. Churchill Livingstone, Philadelphia, Pa.
5. Bayer, A. S., and A. N. Theofilopoulos. 1990. Immunopathogenetic aspects of infective endocarditis. Chest97:204-212.
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