|Title:||Glucosyltransferases of Viridans Streptococci Are Modulins of Interleukin -6 Induction in Infective Endocarditis||Authors:||SHUN, CHIA-TUNG
|Issue Date:||2005||Journal Volume:||v.73||Journal Issue:||n.6||Start page/Pages:||3261-3270||Source:||INFECTION AND IMMUNITY||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-1ß ;. 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.
|Appears in Collections:||法醫學科所|
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.