Protein scouts for dangerous bacteria: How the immune system detects listeria and other bad bacteria
Millions of "good" bacteria exist harmoniously on the skin and in the intestines of healthy people. When harmful bacteria attack, the immune system fights back by sending out white blood cells to destroy the disease-causing interlopers. But how do white blood cells know which bacteria are good and which are harmful?
Northwestern University Feinberg School of Medicine researchers studied one type of white blood cell known as a macrophage, which is among the immune system's first to detect and eliminate harmful bacteria. The research team, led by Christian Stehlik, John P. Gallagher Research Professor of Rheumatology at Feinberg, discovered that the protein NLRP7 serves as a "scout" in macrophage cells, identifying bacterial cell wall components in harmful gram-positive bacteria such as Staphylococcus aureus and Listeria monocytogenes.
The findings will be published in the February 23 issue of the journal Immunity.
"NLRP7 is a novel intracellular pattern recognition receptor that specifically recognizes bacterial cell wall components, known as lipopeptides, in harmful bacteria," says Stehlik, who worked closely with collaborators Andrea Dorfleutner, research assistant professor of medicine at Feinberg, and Yon Rojanasakul, Robert C. Byrd Distinguished Professor and Benedum Distinguished Professor at West Virgina University. "We show that activation of NLRP7 is necessary for eradicating bacterial infections through the formation of protein complexes called inflammasomes, which enable the production of defense factors in immune cells."
Identifying the molecule was complicated, says Sonal Khare, postdoctoral fellow at Feinberg and first author on the research paper, because the family of proteins within macrophages is quite large. "There were 22 likely candidates. To determine which one of these proteins is able to recognize bacteria in macrophages, we had to remove each one of them," she says. Through process of elimination, the team identified NLRP7 as the required protein.
Stehlik says the finding is significant because it contributes to a better understanding of how bacteria such as Listeria and Staphylococcus are recognized by the immune system. Listeria is found in uncooked meats, vegetables, and fruits such as cantaloupes. In 2011, listeria was the cause of the deadliest food contamination outbreak in the U.S. in more than a decade. S. aureus infections are most commonly contracted in hospitals, and 500,000 patients acquire Staphylococcus infections annually in the U.S. Methicillin-resistant S. aureus, or MRSA, strains are highly resistant to commonly-used antibiotics.
Understanding how the immune system recognizes these deadly intruders could one day lead to novel treatment strategies to combat these infections.
"The next phase of research related to NLRP7 and inflammasomes is progressing," says Stehlik. "We are continuing the research to explore mechanisms behind how this NLRP7 inflammasome is formed. We want to know whether we can manipulate this process to make the response stronger. We also will be exploring the use of mouse models in this pathway to study this response in vivo."
More information: The article, "An NLRP7-Containing Inflammasome Mediates Recognition of Microbial Lipopeptides in Human Macrophages" will be available for download on the journal Immunity's web site.
Provided by Northwestern University
- Trudeau Institute reports new approach to treating Listeria infections Oct 17, 2011 | not rated yet | 0
- Innate immune system proteins attack bacteria by triggering bacterial suicide mechanisms May 23, 2011 | not rated yet | 0
- Persistent bacterial infection exploits killing machinery of immune cells Nov 02, 2008 | not rated yet | 0
- New research lights up chronic bacterial infection inside bone Dec 22, 2008 | not rated yet | 0
- Superantigens could be behind several illnesses Nov 29, 2010 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Question of reflection and transmission of TEM wave in normal incidenc
55 minutes ago Suppose TEM wave in +z normal to a boundary on xy plane at z=0. We know *E* & *H* are tangential to the boundary. Let ##\vec E_i=\hat x E##, be the...
the rudyak-krasnolutski effective potencial
1 hour ago Hi ... anyone now how to calculate or the formula of the rudyak-krasnolutski EFFECTIVE potencial ? the effective potencial includes the angular...
Normal force for a lever model
3 hours ago My model is a lever on a table top. One arm is horizontal on the table, while the other arm is raised at an angle alpha. I'm assuming the weight of...
gravity is std. therefore can we rate a 'mass at height' by watts?
8 hours ago For example.... wind turbines are primarily listed by their wattage (1.5MW etc.) Presumably their output is varied according to rotational speed, so...
Calculating on-axis elements of a solenoid
20 hours ago I wanted to mention that this solenoid has many winds over many layers. The thickness of the windings is 2.4 inches coming off of the engineering...
latitude & longitude & air pressure
21 hours ago Hi there, I have a peculiar question. Imagine that you are in a earth position, obtained by google, that gives you the latitude and longitude....
- More from Physics Forums - Classical Physics
More news stories
(Medical Xpress)—Scientists at Emory Vaccine Center have shown that an immune regulatory molecule called IL-21 is needed for long-lasting antibody responses in mice against viral infections.
Immunology 9 hours ago | 5 / 5 (1) | 0 |
Human breastmilk responds quickly to protect the child when there is an infection in mothers or babies, according to new international research led by The University of Western Australia.
Immunology 9 hours ago | 5 / 5 (1) | 0
(Medical Xpress)—A research team, led by Jeremy Barr, a biology post-doctoral fellow, unveils a new immune system that protects humans and animals from infection.
Immunology May 20, 2013 | 4.8 / 5 (25) | 8 |
(Medical Xpress)—Scientists at King's College London have discovered that Vitamin D has the potential to significantly reduce the symptoms of asthma. The study, led by Professor Catherine Hawrylowicz from ...
Immunology May 20, 2013 | 5 / 5 (1) | 0 |
Even while being dragged to its destruction inside a cell, a cancer-promoting growth factor receptor fires away, sending signals that thwart the development of tumor-suppressing microRNAs (miRNAs) before it's dissolved, researchers ...
52 minutes ago | not rated yet | 0 |
Mayo Clinic researchers have used next generation genomic analysis to determine that some of the more aggressive prostate cancer tumors have similar genetic origins, which may help in predicting cancer progression. The findings ...
1 minute ago | not rated yet | 0
(HealthDay)—A shortage of a critical tuberculosis drug has hampered the efforts of health departments across the United States to contain the spread of the highly infectious lung disease, federal officials ...
2 minutes ago | not rated yet | 0
Finnish researchers unveiled new data Thursday to link the Pandemrix flu vaccine to a higher risk of the sleeping disorder narcolepsy in adults.
52 minutes ago | not rated yet | 0
Maintaining a heart healthy lifestyle may also help protect chronic kidney disease patients from developing kidney failure and dying prematurely, according to a study appearing in an upcoming issue of the Journal of the Am ...
22 minutes ago | not rated yet | 0
Don't doubt it when a woman harried by hot flashes says she's having a hard time remembering things. A new study published online in Menopause, the journal of The North American Menopause Society (NAMS), helps confirm with o ...
50 seconds ago | not rated yet | 0