Staphylococcal Enterotoxins, Toxic Shock Syndrome Toxin-I, and Streptococcal Pyrogenic Exotoxins: Some Basic Biology of Bacterial Superantigens

摘要

Staphylococcus aureus and Streptococcus pyogenes are facultative gram-positive cocci that play an important role in a myriad of human illnesses, including food poisoning, skin infections, pharyngitis, life threatening shock, and autoimmune disorders like arthritis, psoriasis, and atopic dermatitis. These ubiquitous bacteria produce various virulence factors that include superantigens like staphylococcal enterotoxins (SE), toxic shock syndrome toxin-i (TSST-1), and streptococcal pyrogenic exotoxins (SPE). To date, the continually expanding literature describes 15 SE and 6 SPE that differ in amino acid sequence and biological effects (i.e. activation of specific T cells). Picomolar concentrations of these toxins activate specific VB-bearing T cells after binding to major histocompatibility complex class II molecules found on antigen presenting cells. The activated T cells vigorously proliferate with a concomitant production of various proinflammatory cytokines, which in sufficient quantities elicit fever, hypotension, and lethal shock. Various in vitro and in vivo models have been developed to study SE, TSST-1, and SPE, thus providing invaluable tools for understanding how these toxins work and discovering potential vaccines as well as therapeutics. This review summarizes the biological properties of, and potential neutralization strategies for, the SE, TSST-1, and SPE.