Bacterial superantigens (SAg) are exotoxins that trigger an excessive immune response that may lead to lethal shock. Because of their ability to induce incapacitation at exceedingly low concentrations and to elicit shock, their ease of production and their exceptional stability, SAgs are classified as Category B biological weapons. Attempts to reverse the deleterious effects of SAg intoxication by blocking downstream effectors such as TNF-a have failed owing to the massive levels induced. We prepared peptide mimetics of the contact domains in the SAg and a novel SAg receptor essential for the induction of Th1 cytokines which prevent lethal shock in a D-galactosamine (D-GalN)-sensitized mouse model of SEB as well as incapacitation in pigs. Since co-exposure of SAg with Gram-negative bacterial endotoxin (LPS) may be more clinically relevant, this proposal will test the hypothesis that antagonist peptides can prevent SAg/LPS svnergistic lethality and rescue exposed animals, while preserving adaptive immune responses.
In Specific Aim I we will determine whether antagonist peptides protect and rescue mice from LPS/SAg lethal synergy. Exposure to SAg and gut-derived LPS likely mimics the clinical situation, and the mechanism of SAg-induced pathology differs from that which occurs with D-GaIN sensitization.
In Specific Aim II, we will define the mechanism of antagonist peptide-mediated protection, show that it is broad-spectrum against SAgs, and assess whether peptide antagonists impair responses to immune stimulation with antigens or host defenses against live infection. IgG purified from the serum of mice challenged with SAg in the presence of peptide antagonist will be.tested by ELISA against peptides from different domains of SAg. These studies will be followed by cross-inhibition ELISA studies to identify IgG levels specific for SAg conserved epitopes. Since recent studies suggest that SAgs may alter APC function, in Specific Aim III we will analyze whether peptide antagonists (1) inhibit SAg effects on human monocytes, particularly Toll-like receptor expression and cytokine induction or (2) impair the ability of human dendritic cells to present B. anthracis antigens to T lymphocytes. These studies will further define a new mechanism of SAg signaling and the efficacy and safety of a novel therapeutic intervention against multiple SAgs. If we are successful, these peptide mimetics could soon be ready for phase I testing.

Public Health Relevance

Exposure to superantigens (SAgs) can cause lethal shock, particularly when it occurs in the presence of Gram-negative bacterial lipopolysaccharide (LPS). Efforts to decrease the massive cytokine release have either failed or led to prolonged T cell anergy. The use of peptide antagonists will be a useful, broad-based therapeutic against a wide range of SAgs that may be deployed in a bioterrorist attack, even when given up to 7 hrs after exposure.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Specialized Center--Cooperative Agreements (U54)
Project #
5U54AI057168-09
Application #
8375166
Study Section
Special Emphasis Panel (ZAI1-DDS-M)
Project Start
Project End
Budget Start
2012-03-01
Budget End
2013-02-28
Support Year
9
Fiscal Year
2012
Total Cost
$245,811
Indirect Cost
$33,102
Name
University of Maryland Baltimore
Department
Type
DUNS #
188435911
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Li, Huiguang; Hwang, Young; Perry, Kay et al. (2016) Structure and Metal Binding Properties of a Poxvirus Resolvase. J Biol Chem 291:11094-104
Ramachandran, Girish; Tennant, Sharon M; Boyd, Mary A et al. (2016) Functional Activity of Antibodies Directed towards Flagellin Proteins of Non-Typhoidal Salmonella. PLoS One 11:e0151875
Ray, Greeshma; Schmitt, Phuong Tieu; Schmitt, Anthony P (2016) C-Terminal DxD-Containing Sequences within Paramyxovirus Nucleocapsid Proteins Determine Matrix Protein Compatibility and Can Direct Foreign Proteins into Budding Particles. J Virol 90:3650-60
Chou, Yi-ying; Cuevas, Christian; Carocci, Margot et al. (2016) Identification and Characterization of a Novel Broad-Spectrum Virus Entry Inhibitor. J Virol 90:4494-510
Fraley, Stephanie I; Athamanolap, Pornpat; Masek, Billie J et al. (2016) Nested Machine Learning Facilitates Increased Sequence Content for Large-Scale Automated High Resolution Melt Genotyping. Sci Rep 6:19218
Levy, Revital; Rotfogel, Ziv; Hillman, Dalia et al. (2016) Superantigens hyperinduce inflammatory cytokines by enhancing the B7-2/CD28 costimulatory receptor interaction. Proc Natl Acad Sci U S A 113:E6437-E6446
Molleston, Jerome M; Sabin, Leah R; Moy, Ryan H et al. (2016) A conserved virus-induced cytoplasmic TRAMP-like complex recruits the exosome to target viral RNA for degradation. Genes Dev 30:1658-70
Riblett, Amber M; Blomen, Vincent A; Jae, Lucas T et al. (2016) A Haploid Genetic Screen Identifies Heparan Sulfate Proteoglycans Supporting Rift Valley Fever Virus Infection. J Virol 90:1414-23
Ramachandran, Girish; Boyd, Mary Adetinuke; MacSwords, Jennifer et al. (2016) Opsonophagocytic Assay To Evaluate Immunogenicity of Nontyphoidal Salmonella Vaccines. Clin Vaccine Immunol 23:520-3
Plaut, Roger D; Stibitz, Scott (2015) Improvements to a Markerless Allelic Exchange System for Bacillus anthracis. PLoS One 10:e0142758

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