Infect. Immun., 09 1997, 3713-3718, Vol 65, No. 9
Copyright © 1997, American Society for Microbiology

Release of tumor necrosis factor alpha in response to Vibrio vulnificus capsular polysaccharide in in vivo and in vitro models

JL Powell, AC Wright, SS Wasserman, DM Hone and JG Morris Jr
Veterans Affairs Medical Center and Division of Infectious Diseases, University of Maryland School of Medicine, Baltimore 21201, USA.

Vibrio vulnificus produces a severe septic shock syndrome in susceptible individuals. Virulence of the bacterium has been closely linked to the presence of a surface-exposed acidic capsular polysaccharide (CPS). To investigate whether CPS plays an additional role in pathogenesis by modulating inflammatory-associated cytokine production, studies were initiated in a mouse model and followed by investigations of cytokine release from human peripheral blood mononuclear cells (PBMCs). Mouse tumor necrosis factor alpha (TNF- alpha) could be detected in serum up to 12 h postinoculation in animals challenged with the encapsulated parent strain MO6-24/O. The unencapsulated strain CVD752 was quickly eliminated by the animals, thus preventing a direct association between serum TNF-alpha levels and the presence or absence of the CPS. Purified CPS from MO6-24/O when injected into D-galactosamine-sensitized mice was a more immediate inducer of TNF-alpha than an equivalent quantity of MO6-24/O lipopolysaccharide (LPS). Both V. vulnificus CPS and V. vulnificus LPS induced inflammation-associated cytokine responses from primary human PBMCs in vitro. CPS elicited TNF-alpha from PBMCs in a dose-dependent manner, with maximal induction at 6 to 10 h, and was not inhibited by polymyxin B. Expression of interleukin-6 (IL-6) mRNAs was also induced in the presence of CPS. Interestingly, while adherent PBMCs secreted high levels of TNF-alpha after stimulation with LPS, they secreted little TNF-alpha in response to CPS. These studies provide evidence that V. vulnificus CPS directly stimulates the expression and secretion of proinflammatory cytokines by murine and human cells and suggest that CPS activation of PBMCs operates through a cellular mechanism distinct from that of LPS.

This article has been cited by other articles:

• Munford, R. S. (2008). Sensing Gram-Negative Bacterial Lipopolysaccharides: a Human Disease Determinant?. Infect. Immun. 76: 454-465 [Full Text]  
• Liu, J.-W., Lee, I.-K., Tang, H.-J., Ko, W.-C., Lee, H.-C., Liu, Y.-C., Hsueh, P.-R., Chuang, Y.-C. (2006). Prognostic Factors and Antibiotics in Vibrio vulnificus Septicemia.. Arch Intern Med 166: 2117-2123 [Abstract] [Full Text]  
• Chatzidaki-Livanis, M., Jones, M. K., Wright, A. C. (2006). Genetic Variation in the Vibrio vulnificus Group 1 Capsular Polysaccharide Operon.. J. Bacteriol. 188: 1987-1998 [Abstract] [Full Text]  
• Joseph, L. A., Wright, A. C. (2004). Expression of Vibrio vulnificus Capsular Polysaccharide Inhibits Biofilm Formation. J. Bacteriol. 186: 889-893 [Abstract] [Full Text]  
• Ashrafian, H. (2003). Hepcidin: the Missing Link between Hemochromatosis and Infections. Infect. Immun. 71: 6693-6700 [Full Text]  
• Powell, J. L., Strauss, K. A., Wiley, C., Zhan, M., Morris, J. G. Jr. (2003). Inflammatory Cytokine Response to Vibrio vulnificus Elicited by Peripheral Blood Mononuclear Cells from Chronic Alcohol Users Is Associated with Biomarkers of Cellular Oxidative Stress. Infect. Immun. 71: 4212-4216 [Abstract] [Full Text]  
• Wright, A. C., Powell, J. L., Kaper, J. B., Morris, J. G. Jr. (2001). Identification of a Group 1-Like Capsular Polysaccharide Operon for Vibrio vulnificus. Infect. Immun. 69: 6893-6901 [Abstract] [Full Text]