NK T cells wazne

[artur737]

Researchers identify cell group key to Lyme disease arthritis
La Jolla Institute and Albany Med researchers show important role of NK T
cells in fighting Lyme disease

SAN DIEGO – (December 3, 2008) A research team led by the La Jolla Institute
for Allergy & Immunology and Albany Medical College has illuminated the
important role of natural killer (NK) T cells in Lyme disease, demonstrating
that the once little understood white blood cells are central to clearing the
bacterial infection and reducing the intensity and duration of arthritis
associated with Lyme disease.

"Our findings are that the NK T cells are critical to preventing the chronic
inflammatory infection that causes Lyme arthritis and they participate in
clearing the bacteria which cause it," said Mitchell Kronenberg, Ph.D., the La
Jolla Institute's president & scientific director and co-senior author on the
study, which used a mouse model of Lyme disease. Lyme disease is caused by
Borrelia burgdorferi, a bacterium transmitted to humans by the bite of
infected deer ticks. Typical symptoms include fever, headache, fatigue, and
sometimes skin rashes. If left untreated, it can spread to the joints, the
heart and the nervous system, and it can lead to serious health problems. Lyme
disease currently is the most common vector (insect)-borne disease in the
United States.

"What this study demonstrates is that NK T cells are an important part of our
defense against Lyme disease," said Timothy J. Sellati, Ph.D., an associate
professor at Albany Medical College and co-senior author on the study. "This
offers the possibility that we can exploit that knowledge therapeutically and
potentially develop immunological agents that can trigger more NK T cells to
aide in fighting this disease." Sellati added that "NK T cells alone cannot
clear Lyme disease, but are a key part of a collective immune defense."

The study's findings are outlined in a paper, "NKT cells prevent chronic joint
inflammation after infection with Borrelia burgdorferi," published this week
in the online version of the journal Proceedings of the National Academy of
Sciences.

In an earlier study published in Nature Immunology, Kronenberg, Sellati and
co-workers had shown that a glycolipid, a type of fat, found in the membrane
of Borrelia burgdorferi triggered an immune response from the NK T cells. "We
had found that if you gave that lipid to mice or humans, it would activate NK
T cells," Kronenberg said. While this suggested the cells might play a
significant role in Lyme disease, "we were missing in vivo (in the body)
evidence showing that the NK T cells were activated following infection and
were important for killing and clearing the Lyme disease bacteria," he said,
noting that the latest study demonstrates this in an animal model.

Sellati said the finding is particularly important because it opens new lines
of investigation as to the causes of chronic Lyme disease. "That's what's so
exciting when you identify a new cell type as playing a central role in
preventing the disease process," he said. "So in those individuals who have a
more severe form of the disease, you can study their NK T cells and see if
there's some deficiency that prevents those NK T cells from killing and
clearing the bacteria."

In their studies, the researchers worked to model the natural route of Lyme
disease infection as closely as possible. "The way people typically get Lyme
disease is that they're out hiking and they get bitten by a deer tick," said
Kronenberg. "So what we did in the lab was to get ticks infected with Borrelia
burgdorferi from collaborators at the University of Connecticut Health Science
Center and then used those ticks to infect mice in a confined and controlled
environment."

The researchers used one group of mice genetically engineered not to have NK T
cells, while the control group had the cells. "The mice that didn't have NK T
cells were not as capable of clearing the (Lyme disease) bacteria," Kronenberg
said. "And they developed a chronic arthritis, while the control mice did
not." He said the results were quite marked. "You could see under the
microscope more numerous inflammatory cells in the joints of the mice that
lacked the NK T cells weeks after infection."

Discovered in the 1990s, NK T cells are disease-fighting white blood cells of
the immune system whose inner workings are still being defined. While most T
cells respond to foreign proteins to protect the body, NK T cells are unique
in that they respond to glycolipids, which are natural biochemicals made of
linked fat and sugar. Prized for initiating a fast and vigorous immune
response, NK T cells are emerging as a subject of significant scientific
interest because of their potential for fighting bacterial infections and
cancer. Kronenberg and Sellati have been among the nation's leaders in
studying these cells.

Problem z NT T cell odpowiedzialny z borelioze. Tak pisza jakby odkryli
Ameryke, a my o tym wiemy od dawna na co wskazywal test CD57. Ale nich im
bedzie. Tak sie potwierdzilo na myszach.
www.eurekalert.org/pub_releases/2008-12/ljif-ric120308.php
Kronenberg's laboratory was among the first to identify bacteria which
naturally induce an immune response from the NK T cells. Thus far, he has
identified two such bacteria— Borrelia burgdorferi and Sphingomonas species, a
fairly benign bacteria found throughout the environment. However, he believes
many other types of bacteria may also trigger the NK T cells. "This is an
exciting possibility that needs to be further explored as it could lead to the
development of treatments for many bacterial diseases."