Many bacterial pathogens important to human health evade the immune system by living within white blood cells. Salmonella enterica, a species of gram-negative bacteria that includes the causative agent of human typhoid fever, resides within a class of white blood cells called macrophages. We have demonstrated that in mice, S. enterica subspecies Typhimurium (Salmonella) resides and replicates within hemophagocytic macrophages (HM?), which are macrophages that have engulfed erythrocytes, platelets, leukocytes and their precursor cells. Our long-term goal is to determine how Salmonella and HM?s interact to cause disease. Mice infected with Salmonella are a natural host-pathogen model system encountered in the wild. Salmonella causes an acute infection in mice that typically resolves into a chronic infection, and the disease course resembles that of typhoid fever. The bacteria colonize the spleen, liver, and the lymph nodes that drain the intestine. We demonstrated the presence of HM?s within the spleen, liver and bone marrow of Salmonella - infected mice and identified HM?s containing Salmonella as late as eight weeks post-infection in the liver, when persistent infection has been established. In Preliminary Studies we developed a flow cytometric assay to identify and separate HM?s from the spleen. This novel methodology along with established approaches enables new exploration of the role of HM?s in disease. The objectives of the current application are to 1) Determine the immunological requirements for hemophagocytosis and the effect of HM? accumulation on the course of murine typhoid fever, 2) Establish whether HM?s formed in response to Salmonella infection in vivo or in culture become anti-inflammatory and whether anti-inflammatory macrophages are permissive for bacterial replication, and 3) Identify regulatory pathways within HM?s needed to make them permissive for Salmonella replication. Completion of these Aims has the potential to elucidate whether hemophagocytosis benefits the host as well as Salmonella. In addition, the information we acquire has potential use in the development of treatments that modulate hemophagocytosis and influence the course of inflammation in infectious and non-infectious circumstances.

Public Health Relevance

The work proposed within has the potential to define novel and important mechanisms of host-pathogen interactions not only for Salmonella, but by inference for other microbes that trigger HM? accumulation, including Mycobacterium tuberculosis, Leishmania species, and Histoplasma capsulatum. The long-term significance of the proposed work is its potential to suggest novel therapeutic approaches to infectious and non-infectious diseases in which HM?s accumulate.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI095395-02
Application #
8433309
Study Section
Host Interactions with Bacterial Pathogens Study Section (HIBP)
Program Officer
Alexander, William A
Project Start
2012-03-01
Project End
2017-02-28
Budget Start
2013-03-01
Budget End
2014-02-28
Support Year
2
Fiscal Year
2013
Total Cost
$348,436
Indirect Cost
$113,436
Name
University of Colorado at Boulder
Department
Biochemistry
Type
Schools of Arts and Sciences
DUNS #
007431505
City
Boulder
State
CO
Country
United States
Zip Code
80309
Bauler, Timothy J; Starr, Tregei; Nagy, Toni A et al. (2017) Salmonella Meningitis Associated with Monocyte Infiltration in Mice. Am J Pathol 187:187-199
McQuate, Sarah E; Young, Alexandra M; Silva-Herzog, Eugenia et al. (2017) Long-term live-cell imaging reveals new roles for Salmonella effector proteins SseG and SteA. Cell Microbiol 19:
Detweiler, Corrella S (2017) A New Way to Beat Intestinal Pathogens. Trends Microbiol 25:169-170
McDonald, Erin M; Pilonieta, M Carolina; Nick, Heidi J et al. (2016) Bacterial Stimulation of Toll-Like Receptor 4 Drives Macrophages To Hemophagocytose. Infect Immun 84:47-55
Brown, Diane E; Nick, Heidi J; McCoy, Melissa W et al. (2015) Increased ferroportin-1 expression and rapid splenic iron loss occur with anemia caused by Salmonella enterica Serovar Typhimurium infection in mice. Infect Immun 83:2290-9
Teske, Sondra S; Detweiler, Corrella S (2015) The biomechanisms of metal and metal-oxide nanoparticles' interactions with cells. Int J Environ Res Public Health 12:1112-34
Silva-Herzog, Eugenia; McDonald, Erin M; Crooks, Amy L et al. (2015) Physiologic Stresses Reveal a Salmonella Persister State and TA Family Toxins Modulate Tolerance to These Stresses. PLoS One 10:e0141343
Nagy, Toni A; Moreland, Sarah M; Detweiler, Corrella S (2014) Salmonella acquires ferrous iron from haemophagocytic macrophages. Mol Microbiol 93:1314-26
Pilonieta, M Carolina; Moreland, Sarah M; English, Christopher N et al. (2014) Salmonella enterica infection stimulates macrophages to hemophagocytose. MBio 5:e02211
Nagy, Toni A; Moreland, Sarah M; Andrews-Polymenis, Helene et al. (2013) The ferric enterobactin transporter Fep is required for persistent Salmonella enterica serovar typhimurium infection. Infect Immun 81:4063-70

Showing the most recent 10 out of 13 publications