Roles of the bacterial cell wall and capsule in induction of tumor necrosis factor alpha by type III group B streptococci

Infect Immun. 1996 Dec;64(12):5042-6. doi: 10.1128/IAI.64.12.5042-5046.1996.

Abstract

Group B streptococci (GBS) are the major cause of sepsis and fatal shock in neonates in the United States. The precise role of tumor necrosis factor alpha (TNF-alpha) in the development of human GBS sepsis has not been defined; however, whole GBS have been shown to induce the production of this inflammatory cytokine. We sought to determine which bacterial cell wall components of GBS are responsible for triggering TNF-alpha production. Human cord blood monocytes were stimulated with encapsulated (COH1) or unencapsulated (COH1-13) whole type III GBS or with purified bacterial components, including type III capsular polysaccharide (III-PS), group B polysaccharide (GB-PS), lipoteichoic acid (LTA), or peptidoglycan (PG). Lipopolysaccharide from Escherichia coli served as a control. Supernatants were harvested at specific timed intervals, and TNF-alpha levels were measured by enzyme-linked immunosorbent assay. Monocytes exposed to COH1 and COH1-13 induced similar amounts of TNF-alpha. III-PS, GB-PS, LTA, and PG each induced TNF-alpha in a time- and concentration-dependent manner. However, TNF-alpha release was significantly greater after stimulation by the GB-PS or PG than after stimulation by III-PS or LTA (P < 0.05). Our findings indicate that GB-PS and PG are the bacterial cell wall components primarily evoking TNF-alpha release. These, alone or in concert with other factors, may be responsible for septic shock accompanying GBS sepsis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bacterial Capsules / metabolism*
  • Cell Membrane / metabolism*
  • Cells, Cultured
  • Humans
  • Monocytes / metabolism*
  • Shock, Septic / microbiology
  • Streptococcal Infections / metabolism*
  • Streptococcus*
  • Tumor Necrosis Factor-alpha / metabolism*

Substances

  • Tumor Necrosis Factor-alpha