Staphylococcal enterotoxin microbial superantigens

Abstract

Staphylococcal enterotoxins are a family of structurally related proteins that are produced by Staphylococcus aureus. In addition to their role in the pathogenicity of food poisoning, these microbial superantigens have profound effects on the immune system, which makes them useful tools for understanding its mechanism of action. These molecules (24-30 kDa) are highly hydrophilic and exhibit low alpha helix and high beta pleated sheet content, suggesting a flexible, accessible structure. Staphylococcal enterotoxins are among the most potent activators of T lymphocytes known. The receptors for staphylococcal enterotoxins on antigen-presenting cells are major histocompatibility complex (MHC) class II molecules. Further, the alpha-helical regions of the class II molecule are essential for function and appear to interact directly with the NH2-terminal region of staphylococcal enterotoxins such as SEA. Recent studies have shown that a complex of staphylococcal enterotoxin and MHC class II molecules is required for binding to the V beta region of the T cell antigen receptor. Staphylococcal enterotoxin mitogenic activity is dependent on induction of interleukin 2, which may be intimately involved in the mechanism of toxicity. The mouse minor lymphocyte stimulating (M1s) "endogenous" self-superantigen has been shown to be a retroviral gene product, so this too is apparently a microbial superantigen. An understanding of the mechanisms of action of these microbial superantigens has implications for normal and pathological immune functions.

Investigation of transphosphorylation between chemotaxis proteins and the phosphoenolpyruvate: sugar phosphotransferase system

“…In the current study, we tested the hypothesis that chemotaxis to PTS substrates is mediated by transphosphorylation between a PTS component and the chemotaxis system. Our preliminary findings have been reported previously [8,9].…”

Administration of Superantigens Protects Mice from LethalListeria monocytogenesInfection by Enhancing Cytotoxic T Cells

“…They were originally identified to cause food poisoning, fever, skin syndrome, or severe toxic shock syndrome (3,18,24). Superantigens also stimulate large numbers of T cells and antigen-presenting cells (3), which lead to greatly increased synthesis of inflammatory cytokines, e.g., IFN-␥, and enhanced innate immunity (10,44,49) and adaptive immunity (17,56) after infection with intracellular parasites such as L. monocytogenes.…”

“…These toxins cause lethal toxic shock in humans and animals (3,15,18,24). They elicit a variety of pathophysiological activities and activate T cells in a T-cell-receptor (TCR) V␤-specific manner.…”

The Staphylococcal Enterotoxins

“…The clinical manifestations of SE intoxication are associated primarily with the large-scale release of pro-inflammatory cytokines, particularly interleukin 2 (IL-2) and tumor necrosis factor a (TNFa) (Marrack and Kappler, 1990;Johnson et al, 1991;Miethke et al, 1992), as a result of the massive proliferation of T lymphocytes. However, fipram SEs exert a direct effect on the target organs, particularly the kidney, thereby contributing to the dysregulation of vascular tone, which results in severe hypotension associated with SE-induced toxic shock (Chatterjee and Jett, 1992;Chatterjee etal., 1995;Khullar and Chatterjee, 1995;Ionin et al, 2000).…”