The long-term goal of this project is to develop a panel of live-attenuated Salmonella enterica serovar Typhimurium (Stm) strains that trigger enhanced inflammasome activation, and determine whether their ability to induce inflammasome activation leads to more robust cellular and humoral protective immune responses in animal models of Salmonella infection. These exploratory studies will provide a foundation for future studies that will mechanistic dissect how manipulating inflammasome activation can be used to enhance effectiveness of immunization. Current vaccines against Salmonella provide at most 60% protection, are not effective in very young children, and do not confer long-lasting immunity. Inflammasome activation in response to pathogens induces inflammatory cell death and production of inflammasome-dependent cytokines of the IL-1 family. The central hypothesis of this proposal is that induction of inflammasome dependent innate and adaptive immune responses contributes to generation of subsequent protective cellular and humoral immune responses. Critically, many pathogens, including Salmonella, modulate inflammasome activation as a central immune evasion strategy. Thus, live-attenuated Salmonella vaccines retain the ability to limit inflammasome activation despite having reduced growth within the host. In a recent genetic screen we identified 16 Salmonella genes that limit inflammasome activation, and demonstrated that deletion of these genes results in elevated inflammasome activation in vitro and in vivo. Using the genes identified in this screen, Aim 1 of this project will first generate a panel of 16 novel live-attenuated strains on the aroA background and test their ability to induce enhanced inflammasome activation in vitro and in vivo. These inflammasome activating strains will be tested in vivo to ensure that they do not induce excessive immunopathology.
Aim 2 of this project will test whether enhanced inflammasome activation during immunization with Salmonella results in qualitatively or quantitatively better T cell and B cell responses compared with immunization with parental aroA bacteria. These studies will provide novel insight into a critical aspect of Salmonella-host interactions, and are likely to provide novel therapeutic targets.
Salmonella infection is the largest single foodborne bacterial cause of morbidity and mortality in the United States. Increasing resistance among Gram-negatives including Salmonella to front-line antibiotics requires new approaches for antimicrobial development. We propose to generate novel live-attenuated vaccine strains by deleting Salmonella factors that modulate inflammasome activation. These studies will likely aid in designing improved anti-bacterial vaccines.
| Philip, Naomi H; DeLaney, Alexandra; Peterson, Lance W et al. (2016) Activity of Uncleaved Caspase-8 Controls Anti-bacterial Immune Defense and TLR-Induced Cytokine Production Independent of Cell Death. PLoS Pathog 12:e1005910 |
| Peterson, Lance W; Philip, Naomi H; Dillon, Christopher P et al. (2016) Cell-Extrinsic TNF Collaborates with TRIF Signaling To Promote Yersinia-Induced Apoptosis. J Immunol 197:4110-4117 |
