Does cat poop parasite play a role in curing cancer?
Toxoplasma gondii (T. gondii) is a
single-celled parasite that is happiest in a cat's intestines, but it can live
in any warm blooded animal.
Found
worldwide, T. gondii affects about one-third of the world's
population, 60 million of which are Americans.
Most
people have no symptoms, but some experience a flu-like illness. Those with
suppressed immune systems, however, can develop a serious infection if they are
unable to fend off T. gondii.
An
Anti-Cancer Agent in Nature?
A
healthy immune system responds vigorously to T.
gondii in a manner that
parallels how the immune system attacks a tumor.
"We
know biologically this parasite has figured out how to stimulate the exact
immune responses you want to fight cancer," said David J. Bzik, PhD,
professor of Microbiology and Immunology, Geisel School of Medicine at
Dartmouth.
In
response to T. gondii, the
body produces natural killer cells and cytotoxic T cells. These cell types wage
war against cancer cells. Cancer can shut down the body's defensive mechanisms,
but introducing T. gondii into a tumor environment can jump
start the immune system.
"The
biology of this organism is inherently different from other microbe-based
immunotherapeutic strategies that typically just tickle immune cells from the
outside," said Barbara Fox, senior research associate of Microbiology and
Immunology. "By gaining preferential access to the inside of powerful
innate immune cell types, our mutated strain of T. gondii reprograms the natural power of the
immune system to clear tumor cells and cancer."
Engineering
T. gondii as a Cancer Vaccine
Since
it isn't safe to inject a cancer patient with live replicating strains of T. gondii, Bzik and Fox
created "cps," an immunotherapeutic vaccine. Based on the parasite's
biochemical pathways, they delete a Toxoplasma gene needed to make a building
block of its genome and create a mutant parasite that can be grown in the
laboratory but is unable to reproduce in animals or people.
Cps is both
nonreplicating and safe. Even when the host is immune deficient, cps still
retains that unique biology that stimulates the ideal vaccine responses.
"Aggressive
cancers too often seem like fast moving train wrecks. Cps is the microscopic,
but super strong, hero that catches the wayward trains, halts their
progression, and shrinks them until they disappear," said Bzik.
Laboratory
Success in Melanoma and Ovarian Cancers
Published
laboratory studies from the Geisel School of Medicine at Dartmouth labs have
tested the cps vaccine in extremely aggressive lethal mouse models of melanoma
or ovarian cancer and found unprecedented high rates of cancer survival.
"Cps
stimulates amazingly effective immunotherapy against cancers, superior to
anything seen before," said Bzik. "The ability of cps to communicate
in different and unique ways with the cancer and special cells of the immune
system breaks the control that cancer has leveraged over the immune
system."
A
Promising Future for a Personalized Cancer Vaccine
This
new weapon against cancer could even be tailored to the individual patient.
"In translating cps therapy to the clinic, we imagine cps will be introduced
into cells isolated from the patient.
Then Trojan Horse cells harboring cps
will be given back to the patient as an immunotherapeutic cancer vaccine to
generate the ideal immune responses necessary to eradicate their cancer cells
and to also provide life-long immunity against any future recurrence of that
cancer," said Bzik.
Fox
and Bzik say a lot more study is needed before cps leaves the laboratory. They
are trying to understand how and why it works so well by examining its
molecular targets and mechanisms.
"Cancer
immunotherapy using cps holds incredible promise for creating beneficial new
cancer treatments and cancer vaccines," said Bzik.
Story Source:
The
above story is based on materials provided by Norris Cotton Cancer
CenterDartmouth-Hitchcock Medical Center. Note: Materials may be edited for
content and length.
Cite This Page:
·
MLA
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APA
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Norris Cotton Cancer CenterDartmouth-Hitchcock Medical
Center. "Does cat poop parasite play a role in curing cancer?." Science
Daily, 15 July 2014.
<www.sciencedaily.com/releases/2014/07/140715095515.htm>.