Anthrax poses a clear and present danger as an agent of biological terrorism. The major virulence factor of Bacillus anthracis is the anthrax toxin, which comprises 3 subunits: protective antigen (PA), edema factor (EF) and lethal factor (LF). LF and PA together form a toxin known as lethal toxin (LT), which appears to play exquisitely different immunomodulatory roles, depending on the dose of toxin used. At low concentrations, it cleaves components of the MAP-kinase pathway (MKK1,2 & 3), thereby rendering macrophages anergic to further stimulation by LPS. The consequences of this for adaptive immunity are not known. Moreover, the effects of LT on dendritic cells (DCs), the most efficient antigen-presenting cells in the body, are not known. At higher concentrations, LT elicits a radically different outcome - lysis of macrophages and systemic inflammation, followed by rapid death of the host. The reason(s) for these strikingly different effects are not known. These mechanisms and their pathophysiological relevance will be investigated in the following aims:
Aim 1 : To determine the effect of LT on routine DC,function and adaptive immunity in vitro Sub-Aim 1a) Activation and viability of DCs from spleens, lungs and skin exposed to different concentrations of LT, Sub-Aim 1b) Stimulation of antigen-specific T cells by DCs cultured with different doses of LT; Sub-Aim 1c) Effect of LT on antigen-specific naive and memory T cells.
Aim 2 : To determine the effect of LT on murine DC function and adaptive immunity in vivo Sub-Aim 2a) Does injection of sub-lethal doses of LT impair DC activation in vivo? Sub Aim 2b) Does injection of sub-lethal doses of LT impair immune stimulatory capacity of DCs in vivo? Sub Aim 2c) To determine the principal cell types and inflammatory mediators of toxicity elicited by high doses of LT Aim 3: To determine the effect of LT on distinct human DC subsets and adaptive immunity in vitro Sub Aim 3b) Activation, viability and function of human monocyte-derived DCs cultured with LT, Sub-Aim 3b) Effect of LT on distinct human DC subsets.
Aim 4 : To determine the pathophysiological relevance of LT-induced suppression during B.anthracis infection Sub Aim 4a) To determine the phenotype, function and microenvironmental localization of DCs in the lymphoid organs, various times after infection with LT-deficient or LT-sufficient strains of B.anthracis Sterne;
Sub Aim 4 b) To determine whether LT suppresses immune function during a B. anthracis infection in macaques. Thus, the overall goal of this proposal is to acquire a deeper, mechanistic understanding of anthrax pathogenesis, and to use this knowledge to devise novel therapeutic modalities, which may be optimally effective at different stages of the infection.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI056499-03
Application #
6846060
Study Section
Special Emphasis Panel (ZRG1-SSS-F (01))
Program Officer
Baker, Phillip J
Project Start
2003-09-01
Project End
2007-02-28
Budget Start
2005-03-01
Budget End
2006-02-28
Support Year
3
Fiscal Year
2005
Total Cost
$380,250
Indirect Cost
Name
Emory University
Department
Pathology
Type
Schools of Medicine
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Murphy, Kenneth M (2011) Comment on ""Activation of ?-catenin in dendritic cells regulates immunity versus tolerance in the intestine"". Science 333:405; author reply 405
Manicassamy, Santhakumar; Reizis, Boris; Ravindran, Rajesh et al. (2010) Activation of beta-catenin in dendritic cells regulates immunity versus tolerance in the intestine. Science 329:849-53
Heffernan, Michael J; Kasturi, Sudhir P; Yang, Stephen C et al. (2009) The stimulation of CD8+ T cells by dendritic cells pulsed with polyketal microparticles containing ion-paired protein antigen and poly(inosinic acid)-poly(cytidylic acid). Biomaterials 30:910-8
Manicassamy, Santhakumar; Ravindran, Rajesh; Deng, Jiusheng et al. (2009) Toll-like receptor 2-dependent induction of vitamin A-metabolizing enzymes in dendritic cells promotes T regulatory responses and inhibits autoimmunity. Nat Med 15:401-9
Sun, Yuliang; Carrion Jr, Ricardo; Ye, Ling et al. (2009) Protection against lethal challenge by Ebola virus-like particles produced in insect cells. Virology 383:12-21
Querec, Troy D; Pulendran, Bali (2007) Understanding the role of innate immunity in the mechanism of action of the live attenuated Yellow Fever Vaccine 17D. Adv Exp Med Biol 590:43-53
Gururajan, Murali; Jacob, Joshy; Pulendran, Bali (2007) Toll-like receptor expression and responsiveness of distinct murine splenic and mucosal B-cell subsets. PLoS One 2:e863
Hao, Jihua; Kwissa, Marcin; Pulendran, Bali et al. (2006) Peptide crosslinked micelles: a new strategy for the design and synthesis of peptide vaccines. Int J Nanomedicine 1:97-103
Querec, Troy; Bennouna, Soumaya; Alkan, Sefik et al. (2006) Yellow fever vaccine YF-17D activates multiple dendritic cell subsets via TLR2, 7, 8, and 9 to stimulate polyvalent immunity. J Exp Med 203:413-24
Agrawal, Anshu; Dillon, Stephanie; Denning, Timothy L et al. (2006) ERK1-/- mice exhibit Th1 cell polarization and increased susceptibility to experimental autoimmune encephalomyelitis. J Immunol 176:5788-96

Showing the most recent 10 out of 15 publications