Download The Role of Interleukin-10 in Burkholderia Infection of Human

The Role of Interleukin-10 in Burkholderia Infection
of Human Mononuclear Cells
Amy K. Dickey MD MSc, Johanna D. Robertson BS, T. Eoin West MD MPH
Department of Medicine, University of Washington, and Harborview Medical Center, Seattle, WA, USA
Background
Results
•
The flagellated bacterium and potential bioterrorism agent Burkholderia
pseudomallei is responsible for melioidosis, a common cause of pneumonia
and sepsis in Southeast Asia and tropical Australia.
• Because use of live B. pseudomallei is restricted, a similar but less pathogenic
bacteria, B. thailandensis, is a commonly used instead as a model organism .
• A common TLR5 polymorphism, TLR51174C>T, results in a truncated TLR5 protein
that does not signal in response to flagellin.
• Individuals carrying TLR51174T are protected against death after infection with
melioidosis.
• In healthy carriers of the TLR51174T polymorphism, stimulation of whole blood
with flagellin or B. pseudomallei results in lower IL-10 release as compared to
wild-type individuals.
• Interferon gamma (IFN-γ) has bactericidal activity against intracellular bacteria
such as B. pseudomallei, and is known to be down-regulated by IL-10.
 We hypothesize that in primary blood mononuclear cells infected with B.
pseudomallei, suppression of IL-10 increases both IFN-γ and intracellular
bactericidal activity.
B. pseudomallei (1026b and
K9) and Salmonella
typhimurium flagellin (Flag)
induce lower IL-10 levels in
carriers of TLR51174T.
West TE et al. J Immunol. 2013;
190:3373-3379
B. pseudomallei stimulation but not B.
thailandensis infection induces IL-10 release
Il-10 inhibition does not affect intracellular
survival of B. thailandensis
IL-10 inhibition may improve survival of
PBMCs infected with B. thailandensis
B. pseudomallei stimulation or B. thailandensis
infection induces minimal IFN-γ release, even with
IL-10 inhibition
Conclusions
•
Methods
Primary blood mononuclear cells (PBMCs) were isolated from the blood of
healthy individuals, treated with or without IL-10 monoclonal antibody inhibition,
and stimulated with either heat-killed B. pseudomallei (BP) or live Burkholderia
thailandensis (BT), both at 100 MOI, for the indicated length of time or 6 hours if
not indicated. IL-10 and IFN-γ expression were measured in cell supernatants by
ELISA. PBMC survival was determined using the Guava ViaCount Assay. The
number of intracellular bacteria was assessed by washing and lysing cells,
followed by plating cell lysates on LB agar at various dilutions. Colony forming
units were counted after 24 hours.
•
•
•
IL-10 is released in response to heat-killed B. pseudomallei but not live B.
thailandensis, limiting the ability to use B. thailandensis as a model
organism for the study of the role of IL-10 in melioidosis infection.
IL-10 inhibition does not affect IFN-γ release or intracellular bacterial
survival in PBMCs infected with live B. thailandensis.
Our data suggests that IL-10 inhibition may increase the survival of
PBMCs infected with live B. thailandensis.
Studies using live and not heat-killed B. pseudomallei are required to
conclusively support or reject the hypothesis that in B. pseudomallei
infection of PBMCs, suppression of IL-10 increases both IFN-γ and
intracellular bactericidal activity.
Funding for this project was provided by R01 HL113382.
Contact [email protected] for more information