Salmonella enterica has been observed to manipulate the host pro-inflammatory immune response to optimize its own growth conditions. However, how S. enterica impacts and manipulates anti-inflammatory responses is poorly understood. Characterizing the mechanisms by which pathogens can trigger anti- inflammatory cytokines could have profound consequences for developing treatments for both infectious diseases and autoimmune disorders that are regulated by this anti-inflammatory cytokine. Thus, my long-term goal is to understand the mechanisms of pathogen manipulation of anti-inflammatory pathways and the resulting implications on infection and autoimmunity. The objective of this application is to characterize how S. enterica serovar Typhimurium induces production of the anti-inflammatory cytokine interleukin-10 (IL-10) and the role this plays on the progression and severity of infection. In pursuit of this objective, naturally occurring variation n the ability of S. enterica serovars to induce IL-10 revealed a genetic region present only in IL-10 inducing serovars. The hypothesis is that this region contains a gene encoding a Salmonella secreted effector that manipulates a host signaling pathway to produce IL-10. Deletion of this gene renders Salmonella unable to induce IL-10. Indicative of likely in vivo relevance, the deletion induces less IL-10 in mouse spleens, as measured by both qRT-PCR and IL-10-GFP reporter mice.
Aim 1 of this proposal will determine how Salmonella induces IL-10 production. The hypothesis is that this unique protein is sufficient to induce IL-10 and interacts with host proteins to effect this response. This will be tested through 1) determining if expression of the gene in host cells is sufficient to induce IL-10 without accompanying S. enterica infection; 2) identification via RNAseq of host pathways altered in cells infected with wildtype vs. a mutant unable to induce IL-10; and 3) characterization of physical interactions with host proteins.
Aim 2 will identify the cell types that are producing IL-10 in vivo and characterize the effects of the I-10-inducing factor and the induced IL-10 on infection progression and outcome. The hypothesis is that S. Typhimurium lacking induction of this anti-inflammatory pathway will show a defect in virulence. This will be tested by utilizing mouse models to examine bacterial loads, cytokine responses, and survival. IL-10-GFP reporter mice will be used to identify which cell types are producing IL-10 by flow cytometry with cell type-specific markers. Elucidating how intracellular S. enterica induces the IL-10 anti-inflammatory pathway will lead to a better understanding of how pathogens can modulate inflammation and how this can contribute to the effectiveness of clearance, chronic infection, and autoimmunity. In addition, the initiation of this IL-10 productio pathway may represent a new target for autoimmune therapies.

Public Health Relevance

The objective of this application is to characterize how Salmonella induces IL-10 production and its role on the progression and severity of infection. Elucidating how intracellular S. enterica induces the IL-10 anti-inflammatory pathway will lead to a better understanding of how pathogens can modulate inflammation and how this can contribute to the effectiveness of clearance, chronic infection, and autoimmunity. This characterization could have profound consequences for developing treatments for both infectious diseases and autoimmune disorders that are regulated by this anti-inflammatory cytokine.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
5F31AI124544-02
Application #
9236068
Study Section
Special Emphasis Panel (ZRG1-F13-C (20)L)
Program Officer
Alexander, William A
Project Start
2016-03-01
Project End
2018-02-28
Budget Start
2017-03-01
Budget End
2018-02-28
Support Year
2
Fiscal Year
2017
Total Cost
$33,941
Indirect Cost
Name
Duke University
Department
Genetics
Type
Schools of Medicine
DUNS #
044387793
City
Durham
State
NC
Country
United States
Zip Code
27705