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Transcript
Parasitic Pathogenesis of
Toxoplasma gondii
Josh Materi
Graduating Class of 2015
University of Wyoming
Background on T. gondii
•
•
Protozoan parasite
Infects warm blooded animals via:
–
–
–
–
–
•
•
Undercooked meat
Food or water contaminated with cat feces
Blood transfusion
Organ transplantation
Transplacentally from mother to fetus
Chronic infection with cysts typically found in
skeletal muscle, myocardium, brain, and eyes
Two life stages:
– Tachyzoite
• Fast growing, disseminating, acute stage
– Bradyzoite
• Slow growing, cyst forming, chronic stage
Background on T. gondii
•
Worldwide epidemic
– > 60 million people infected in the U.S.
•
Symptoms
–
–
–
–
–
–
–
•
Most people unaware of infection
Swollen lymph nodes
Muscle aches
Brain damage: seizures, encephalitis, brain
lesions, etc.
Lung problems
Blurred vision
Stillbirth or miscarriage
Immunologically compromised
individuals are at greatest risk
– Infants
– Individuals with AIDS
Background on T. gondii
T. gondii Establishes a Chronic
Infection
Individual
becomes
infected
Immune
response
controls
infection
Alteration in
immune cells
(CD8 T cells)
causes the
immune
response to
fail
T. gondii
excapes and
establishes a
chronic
infection
Loss of CD8 T Cells means loss of…
• Host defense against
intracellular pathogens that
live or produce in the cell’s
cytosol
• Immunological memory
What is happening to these CD8 T Cells?
NK
NK cells contributing immune
exhaustion
Suppress CD8
T Cells
Z
Z
Activated CD8 PD-1
T cell
Exhausting PD-1
Activated CD8
T cell
ExhaustedC
D8 T cell
PD-1
IFN+, CTL
Cyst wall
Z
Z
What is happening to these CD8 T Cells?
NK
NK cells contributing immune
exhaustion
Suppress CD8
T Cells
Z
Z
Activated CD8 PD-1
T cell
ExhaustedC
D8 T cell
PD-1
IFN+, CTL
Cyst wall
NK
Exhausting PD-1
Activated CD8
T cell
Z
Z
Experimental Focus
Specific Aim 1: Determine if NK
cells suppress CDB T cell
function, thereby promoting
immune exhaustion.
Specific Aim 2: Define the
mechanism by which NK cells
contribute to immune
exhaustion.
NK
NK cells contributing immune
exhaustion
Suppress CD8
T Cells
Z
Z
Exhausting PD-1
Activated CD8
T cell
ExhaustedC
D8 T cell
PD-1
Z
Z
Experimental methods
Infected mice with
T. gondii
5 weeks post
infection,
administer NK
cell blocking
antibody for two
weeks
Flow
cytometry
Findings
After NK cell depletion:
– CD8 T- cells were at a
higher number
– The overall health of the
mice improved,
increasing the life span
Hypotheses for NK mode of action
1. NK cells are
suppressing CD8 T cell
function by blocking
IFN+, CTL
2. NK cells are indirectly
suppressing CD8 T
cells by blocking other
immune cells (APCs)
3. NK cells are killing the
CD8 T cells
Significance of this research
• Potential cure for the millions infected with T.
gondii
• Applicable to other chronic infections
• Better medical treatment of cancerous
growths, which NK cells help regulate
Acknowledgments
UW Gigley Lab:
Dr. Jason Gigley
Daria Ivanova
David Donley
Ryan Krempels
Steve Denton
Kaitlyn Weitzman
Sari Mayhue
David Stephenson
David Rach
Tyler Graham
Funding
INBRE
Questions?
Thank you for coming!!