Therapeutic Down-Modulators of Staphylococcal Superantigen-Induced Inflammation and Toxic Shock

Staphylococcal enterotoxin B (SEB) and related superantigenic toxins are potent stimulators of the immune system and cause a variety of diseases in humans, ranging from food poisoning to toxic shock. These toxins bind directly to major histocompatibility complex (MHC) class II molecules on antigen-presenting cells and specific Vβ regions of T-cell receptors (TCR), resulting in hyperactivation of both monocytes/macrophages and T lymphocytes. Activated host cells produce massive amounts of proinflammatory cytokines and chemokines, activating inflammation and coagulation, causing clinical symptoms that include fever, hypotension, and shock. This review summarizes the in vitro and in vivo effects of staphylococcal superantigens, the role of pivotal mediators induced by these toxins in the pathogenic mechanisms of tissue injury, and the therapeutic agents to mitigate the toxic effects of superantigens

gld and lpr hematopoietic cell transfers: common and different serological features of the C57BL/6 chimeras

Homozygosity for either the lpr (lymphoproliferation) or the gld (generalized lymphoproliferative disease) mutation in mice causes the development of strikingly similar hyperglobulinemia and lymphoproliferative syndromes. Nevertheless, previous studies of various C57BL/6 chimeras obtained by reconstitution of irradiated recipients with hematopoietic cells (HC), differing at the bg, gld, lpr, and/or nu loci, showed that the lpr and gld syndromes had distinct etiologies. The [lpr-->lpr], [gld-->gld], and [gld-->wild] chimeras developed lymphoid hyperplasia, while the [lpr-->wild, bg, or gld] and [nulpr-->wild or bg] chimeras developed a severe persistent lymphoid aplasia. We now show that the serological status (immunoglobulin (Ig) levels and Ig isotype distribution) of the [lpr-->lpr], [gld-->gld], and [gld-->wild] chimeras were roughly equivalent to those of genetic lpr and gld mice. Despite their lymphoid aplasia, all the [lpr-->non-lpr] chimeras displayed surprisingly normal serum Ig levels, similar to [wild-->wild] control chimeras, although always with some abnormal isotype profile. In fact, an early but transient increase of serum IgG1 levels was found in all [lpr-->wild, bg, or gld], [lpr-->lpr], [nulpr-->wild or bg], [wild-->lpr], and [gld-->wild or gld] types of chimeras. Despite a common early behavior, the host type and/or the gld or lpr HC origin may cause later divergences of the gld or lpr HC grafted chimeras

Cytokine deviation induced by intrathymic injection of staphylococcal enterotoxin B (SEB).

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HIV-1 viral protein-R (VPR) protects against lethal superantigen challenge while maintaining homeostatic T cell levels in vivo

The HIV-1 accessory protein Vpr exhibits many interesting features related to macrophage and T cell biology. As a viral protein or as a soluble molecule it can suppress immune cell activation and cytokine production in vitro in part by targeted inhibition of NF-kappa B. In this regard we sought to test its effects in vivo on an NF-kappa B-dependent immune pathway. We examined the activity of Vpr in a lethal toxin-mediated challenge model in mice. Intravenous delivery of Vpr was sufficient to protect mice from lethal challenge with staphylococcal endotoxin B (SEB). Furthermore, Vpr protected host CD4(+) T cells from in vivo depletion likely by preventing induction of AICD of SEB-exposed cells in a post-toxin-binding fashion. Understanding the biology of Vpr's activities in this model may allow for new insight into potential mechanisms of hyperinflammatory disease and into Vpr pathobiology in the context of HIV infection