Inhibition of Staphylococcal Enterotoxin B-Induced Lymphocyte Proliferation and Tumor Necrosis Factor Alpha Secretion by MAb5, an Anti-Toxic Shock Syndrome Toxin 1 Monoclonal Antibody (original) (raw)
Related papers
Infection and Immunity
Staphylococcus aureus toxic shock syndrome toxin 1 (TSST-1) is involved in the pathogenesis of toxic shock syndrome and perhaps other staphylococcal diseases. Recently, the C-terminal part of the TSST-1 toxin has been shown to be responsible for mitogenic activity in animal models. We studied the role of the C-terminal structural unit of TSST-1 with regard to proliferation, cytokine release (tumor necrosis factor alpha [TNF-␣], interleukin-6 [IL-6], and IL-8), mRNA expression for IL-6, IL-8, IL-10, TNF-␣, and CD40 ligand (CD40L), synthesis of immunoglobulin E (IgE), IgA, IgG, and IgM, CD23 expression, and soluble CD23 (sCD23) release from human peripheral blood mononuclear cells (PBMC). For this purpose, we used the recombinant wild-type TSST-1 (p17) mutant toxin Y115A (tyrosine residue modified to alanine) and toxin H135A (histidine residue modified to alanine). Unmodified toxin p17 and mutant toxin Y115A, at a concentration below 5 ng, to a lesser degree, induced a strong proliferation. Toxin p17 followed by toxin Y115A was the most pronounced inducer for mRNA expression for IL-10 and CD40L and cytokine generation (mRNA and protein) for TNF-␣, IL-6, and IL-8. Mutant protein H135A failed to activate human PBMC. Both toxins p17 and, to a lesser degree, Y115A significantly suppressed IL-4-and anti-CD40-induced synthesis of all four Igs as well as IL-4-induced CD23 expression and sCD23 release. Mutant toxin H135A failed to do so. Thus, our data show that a region in the C terminus of TSST-1 is responsible not only for mitogenic activity but also for additional immunomodulating biological activities of TSST-1. More specifically, histidine residue H135A of the 194-amino-acid toxin appears to be critical for the expression of biological activities in a human in vitro model.
BMC Biotechnology, 2022
Background Staphylococcal superantigens are virulence factors that help the pathogen escape the immune system and develop an infection. Toxic shock syndrome toxin (TSST)-1 is one of the most studied superantigens whose role in toxic shock syndrome and some particular disorders have been demonstrated. Inhibiting TSST-1 production with antibiotics and targeting TSST-1 with monoclonal antibodies might be one of the best strategies to prevent TSST-1induced cytokines storm followed by lethality. Results A novel single-chain variable fragment (scFv), MS473, against TSST-1 was identified by selecting an scFv phage library on the TSST-1 protein. The MS473 scFv showed high affinity and specificity for TSST-1. Moreover, MS473 could significantly prevent TSST-1-induced mitogenicity (the IC 50 value: 1.5 µM) and cytokine production. Conclusion Using traditional antibiotics with an anti-TSST-1 scFv as a safe and effective agent leads to deleting the infection source and preventing the detrimental effects of the toxin disseminated into the whole body.
Immunology, 1998
A number of investigators have utilized a variety of methods to identify the structural basis for the interaction of superantigens with the T-cell receptor b-chain. The previous studies strongly suggest that a region of the toxin near residues N23, Y61, Y91 and D209 is important for this binding activity. Examination of crystal structure data shows that these residues line the rim of one side of a shallow cavity in the toxin. In an attempt further to define the face of the staphylococcal enterotoxin B (SEB) molecule involved in the interaction with the b-chain, we have employed a polymerase chain reaction (PCR)-based, site-specific mutagenesis method to generate amino acid substitutions of residues on the opposite side of this putative T-cell receptor interaction cavity. Our results show that Y175 and N179 appear to be involved in the function of this superantigen, since each of several substitutions at this position exhibits a significantly reduced ability to induce T-cell proliferation. At the same time, mutation of the proximal Y186 does not alter the superantigen activity of SEB. Binding analysis of these mutants shows that class II binding activity is not significantly altered. Analysis of the responding T cells shows that the mutant toxins maintain T-cell receptor Vb selectivity. However, responses of T cells bearing the Vb8.1 allele appear to be particularly diminished. When viewed in the context of other results reported in the literature, our results suggest that the T-cell receptor interaction site involves SEB residues which ring both the Y175/N179-side and the N23-side of a cavity on one side of the toxin molecule.
Infection and Immunity
A series of 13 synthetic peptides, approximately 30 amino acids each, which spanned the entire sequence of staphylococcal enterotoxin B (SEB) were tested to evaluate their effects on T-cell proliferation in a culture system containing elutriated human peripheral blood lymphocytes incubated with a specific ratio of mononuclear cells. Four peptide regions were found to inhibit SEB-induced proliferation; they included sequences 1 to 30 (previously thought to be involved in major histocompatibility complex class II binding), 61 to 92 (sequences which relate to the T-cell receptor site), 93 to 112 (a linear sequence corresponding to the cysteine loop), and 130 to 160 (containing a highly conserved sequence, KKKVTAQEL). Antisera raised to this last peptide were capable of neutralizing SEB-induced proliferation. Antisera raised against the peptides which overlapped this sequence also were somewhat inhibitory. Neutralizing antisera were not produced from any other peptide sequence tested. T...
Potent Neutralization of Staphylococcal Enterotoxin B by Synergistic Action of Chimeric Antibodies
Infection and Immunity, 2010
31 32 Staphylococcal Enterotoxin B (SEB), a shock-inducing exotoxin synthesized by 33 Staphylococcus aureus, is an important cause of food poisoning and is a Class B 34 bioterrorism agent. SEB mediates antigen-independent activation of a major subset of 35 the T-cell population by crosslinking TCRs of T-cells with class II MHC molecules of 36 antigen-presenting cells, resulting in the induction of antigen independent proliferation 37 and cytokine secretion by a significant fraction of the T-cell population. Neutralizing 38 antibodies inhibit SEB-mediated T cell activation by blocking the toxin's interaction with 39 the TCR or MHC-II and provide protection against the debilitating effects of this 40 superantigen. We derived and searched a set of monoclonal mouse anti-SEB antibodies 41 to identify neutralizing anti-SEB antibodies that bind to different sites on the toxin. A 42 pair of noncrossreactive, neutralizing anti-SEB monoclonal antibodies (MAbs) was found 43 and a combination of these antibodies inhibited SEB-induced T-cell proliferation in a 44 synergistic rather than merely additive manner. In order to engineer antibodies more 45 suitable than mouse MAbs for use in humans, the genes encoding the VL and VH gene 46 segments of a synergistically-acting pair of mouse MAbs were grafted, respectively, onto 47 genes encoding the constant regions of human Igκ and human IgG1, transfected into 48 mammalian cells and used to generate chimeric versions of these antibodies that had 49 affinity and neutralization profiles essentially identical to their mouse counterparts. 50 When tested in cultures of human PBMCs, or splenocytes derived from HLA-DR3 51 transgenic mice, the chimeric human-mouse antibodies synergistically neutralized SEB-52 induced T cell activation and cytokine production. 53 on December 6, 2017 by guest http://iai.asm.org/ Downloaded from 54 Staphylococcal Enterotoxin B (SEB) is one of several potent exotoxins secreted 55
Protein Science, 1996
Toxic shock syndrome toxin-1 (TSST-I) is one of a family of staphylococcal exotoxins recognized as microbial superantigens. The toxin plays a dominant role in the genesis of toxic shock in humans through a massive activation of the immune system. This potentially lethal illness occurs as a result of the interaction of TSST-1 with a significant proportion of the T-cell repertoire. TSST-I, like other superantigens, can bind directly to class I1 major histocompatibility (MHC class 11) molecules prior to its interaction with entire families of VP chains of the T-cell receptor (TCR). The three-dimensional structure of a mutant (His-135-Ala) TSST-1 was compared with the structure of the native (wild-type) TSST-1 at 2.5 A resolution. The replacement of His 135 of TSST-1 with an Ala residue results in the loss of T-cell mitogenicity and toxicity in experimental animals. This residue, postulated to be directly involved in the toxin-TCR interactions, is located on the major helix 012, which forms the backbone of the molecule and is exposed to the solvent. In the molecular structure of the mutant toxin, the helix a2 remains unaltered, but the His to Ala modification causes perturbations on the neighboring helix a1 by disrupting helixhelix interactions. Thus, the effects on TCR binding of the His 135 residue could actually be mediated, wholly or in part, by the a 1 helix.
Journal of Immune Based Therapies and Vaccines, 2010
Background: Staphylococcal enterotoxins are considered potential biowarfare agents that can be spread through ingestion or inhalation. Staphylococcal enterotoxin B (SEB) is a widely studied superantigen that can directly stimulate T-cells to release a massive amount of proinflammatory cytokines by bridging the MHC II molecules on an antigen presenting cell (APC) and the Vβ chains of the T-cell receptor (TCR). This potentially can lead to toxic, debilitating and lethal effects. Currently, there are no preventative measures for SEB exposure, only supportive therapies. Methods: To develop a potential therapeutic candidate to combat SEB exposure, we have generated three human B-cell hybridomas that produce human monoclonal antibodies (HuMAbs) to SEB. These HuMAbs were screened for specificity, affinity and the ability to block SEB activity in vitro as well as its lethal effect in vivo.