TB bacteria use the body's stem cells to protect themselves
December 8, 2010 by Lin Edwards
M. tuberculosis bacterial colonies. Image credit: Centers for Disease Control and Prevention.
(PhysOrg.com) -- Tuberculosis kills around 1.7 million people globally each year, and the World Health Organization (WHO) estimates around a third of the human population carries the disease, which becomes active in 10 percent of affected people. The bacteria causing the disease are becoming increasingly resistant to drugs, and new ways of treating the disease need to be found urgently.
Mycobacterium tuberculosis (M.tb), the bacterium causing tuberculosis (TB) is able to produce a persistent presence in its host even if there is a strong immune response, but the mechanism by which it is able to do this is poorly understood. Now, new research by scientists in India has gone some way to solving the mystery.
It was already known that the immune system response to M.tb produces a waxy coating over the bacteria creating clumps called granulomas. The granulomas quarantine the bacteria but do not kill them, and they can remain dormant for many years. If the bodys immune system is weakened, the bacteria can go on to produce active tuberculosis.
The researchers, led by Gobardhan Das from New Delhi, infected mice with a low dose of M.tb, and found the infection caused an increase in the number of the hosts own mesenchymal stem cells (MSCs) in the mice spleens and lung granulomas, and a suppression of T-lymphocyte cells (T-cells). The stem cells formed a protective coating around the granulomas and produced nitric oxide and other immunosuppressant molecules.
Das said the amount of nitric oxide produced is not enough to kill the M.tb bacteria but it inactivates the T-cells, creating an equilibrium. These actions protected the M.tb bacteria from attack by the bodys T-cells and white blood cells, which would otherwise destroy them. The state of equilibrium could further explain why the disease remains latent in 90 percent of those infected and can remain present for the persons lifetime.
Biopsies taken of granulomas in human tuberculosis patients support the findings of the study in mice, and suggest the same mechanism applies in humans.
MSCs originate in the bone marrow and can differentiate to form cells such as muscle, cartilage, bone or blood cells. They also play a role in immunosuppression and can migrate to other areas of the body to help in the repair of inflamed tissue such as that found in tumors and Crohns disease.
The research findings, which are the first to show a bacterium using the hosts own stem cells to help in its own survival, could lead to new methods of attacking the disease. They suggest if drugs could be developed that target the specific MSCs forming the protective layer around the granulomas, this would give the bodys own immune responses a chance to destroy the TB bacteria. Das likened the MSCs to creating a nest for the TB bacteria and if the nest is destroyed the bacteria would be exposed to attack by the bodys immune system.
The paper was published earlier this week in the Proceedings of the National Academy of Sciences (PNAS).
More information: Mycobacteriumtuberculosis evades host immunity by recruiting mesenchymal stem cells, Shilpa Raghuvanshi et al., doi:10.1073/pnas.1007967107
© 2010 PhysOrg.com
-
From lemons to lemonade: Reaction uses carbon dioxide to make carbon-based semiconductor,
28 comments
-
Thioridazine kills cancer stem cells in human while avoiding toxic side-effects of conventional cancer treatments,
3 comments
-
SpaceX private rocket blasts off for space station (Update),
41 comments
-
Climate scientists say they have solved riddle of rising sea,
30 comments
-
Scotland passes turbine test to harness tidal power,
40 comments
-
Potential Breakthrough in Seizure Control
5 hours ago
-
Popping/Cracked sternum.
9 hours ago
-
Which Mental Illness Encompasses This Problem?
10 hours ago
-
A question about drug tolerance
May 23, 2012
-
Poor nutrition leading to overeating?
May 23, 2012
-
Math and dyslexia?
May 21, 2012
- More from Physics Forums - Medical Sciences
More news stories
Travel to high altitudes tied to Crohn's, colitis flare-ups
(HealthDay) -- People with inflammatory bowel disease, which includes Crohn's disease and colitis, may be at increased risk for flare-ups when they fly or travel to high altitudes for skiing or mountain climbing, ...
Medicine & Health / Inflammatory disorders
44 minutes ago |
not rated yet |
0
|
Transvaginal mesh op restores pelvic organ prolapse at price
(HealthDay) -- Transvaginal mesh (TVM) procedures are effective for anatomical restoration of pelvic organ prolapse (POP), but patients report a worsening of sexual function following surgery, according to ...
21 minutes ago |
not rated yet |
0
Skp2 activates cancer-promoting, glucose-processing Akt
HER2 and its epidermal growth factor receptor cousins mobilize a specialized protein to activate a major player in cancer development and sugar metabolism, scientists report in the May 25 issue of Cell.
18 hours ago |
not rated yet |
0
|
Cancer may require simpler genetic mutations than previously thought
Chromosomal deletions in DNA often involve just one of two gene copies inherited from either parent. But scientists haven't known how a deletion in one gene from one parent, called a "hemizygous" deletion, can contribute ...
21 hours ago |
not rated yet |
0
|
First study to suggest that the immune system may protect against Alzheimer's changes in humans
Recent work in mice suggested that the immune system is involved in removing beta-amyloid, the main Alzheimer's-causing substance in the brain. Researchers have now shown for the first time that this may apply in humans.
Medicine & Health / Alzheimer's disease & dementia
22 hours ago |
5 / 5 (3) |
0
|
SpotterRF debuts Radar Backpack Kit (w/ Video)
(Phys.org) -- SpotterRF has announced a special radar backpack kit designed to enhance situational awareness for soldiers on the ground. The company says its special radar is designed for warfighters as part ...
Astronauts enter world's 1st private supply ship
(AP) -- Space station astronauts floated into the Dragon on Saturday, a day after its heralded arrival as the world's first commercial supply ship.
Australia hails surprise super-telescope decision
Australia has hailed a surprise decision giving it a role in a radio telescope project aimed at revolutionising astronomy, vowing to draw on its decades of experience in space science.
SpaceX capsule has 'new car' smell, astronauts say
SpaceX's Dragon cargo vessel smells like a new car, said astronauts at the International Space Station after opening the hatches Saturday following the spacecraft's landmark mission to the orbiting lab.
Thousands of shellfish found dead in Peru
Thousands of crustaceans were found dead off the coast of Lima following the mystery mass death of dolphins and pelicans, the Peruvian Navy said Friday.
Astronomers seize last chance in lifetime for Venus Transit
Astronomers are gearing for one the rarest events in the Solar System: an alignment of Earth, Venus and the Sun that will not be seen for another 105 years.