Good bugs gone bad: Gut immune cells keep beneficial microbes in their place
June 6, 2012 in Medical research
This is a color-enhanced tissue section from a healthy mouse that displays the presence of commensal bacteria (Alcaligenes species, purple) on the interior of a Peyer's patch (gut-associated lymphoid tissue) and overlaying intestinal epithelial cells (green). Credit: Gregory Sonnenberg, Ph.D.; David Artis, Ph.D., Perelman School of Medicine University of Pennsylvania; Science
The healthy human intestine is colonized with over 100 trillion beneficial, or commensal, bacteria of many different species. In healthy people, these bacteria are limited to the intestinal tissues and have a number of helpful properties, including aiding in the digestion of food and promoting a healthy immune system.
However, when it comes to commensal bacteria, location is key. While commensal bacteria in the intestine provide positive effects, several chronic human diseases, including HIV/AIDS, inflammatory bowel disease, viral hepatitis, and obesity are associated with the spread of these intestinal commensal bacteria to the blood stream and other peripheral tissues, which can cause chronic inflammation. 'Good bugs' that promote normal health can 'turn bad' if found in the wrong location.
In earlier work, researchers from the Perelman School of Medicine at the University of Pennsylvania found that barrier surfaces -- the skin, gut, lung are guarded by immune cells and limit the inner body's exposure to viruses, bacteria, and parasites, as well as allergens and pollutants. But, how immune cells play a role in limiting the location of commensal bacteria to intestinal and other barrier sites remains unclear.
Now, David Artis, PhD, associate professor of Microbiology, and Gregory F. Sonnenberg, PhD, a postdoctoral researcher in the Artis lab, have identified that immune cells, called innate lymphoid cells, are resident in the intestinal tissues of healthy humans, mice, and non-human primates, and are critical in limiting the location of commensal bacteria. If the innate lymphoid cells are depleted in mice, commensal bacteria move to peripheral tissues and promote inflammation. The research appears this week in Science.
Remarkably, the commensal bacteria that were found in peripheral tissues were all members of a group called Alcaligenes, indicating that the immune system may have developed highly selective pathways to regulate containment of different groups of commensal bacteria.
"A fundamental question that has puzzled researchers for many years is how did the human body evolve to accommodate all these commensal bacteria and keep them in their correct locations?," asks Artis. "The indication from these studies is that the body may have many different pathways to limit the spread of commensal bacteria and these pathways may be tailored to specific types of bacteria."
Supporting experiments in animal models, Alcaligenes-specific immune responses were associated with patients with Crohn's disease or progressive hepatitis C virus infection, two debilitating human diseases linked to the spread of commensal bacteria to systemic tissues.
"The identification of systemic Alcaligenes-specific immune responses in these patient populations suggests that, coupled with other groups of bacteria, the spread of Alcaligenes to tissues outside the intestine may be contributing to chronic inflammation and disease progression," suggests Sonnenberg.
Innate immune cells may become impaired in chronic human diseases, resulting in the spread of Alcaligenes bacteria and pathologic inflammation, which may represent a novel pathway to target in human disease, say the investigators.
"Although it's still early days for this line of research, these findings suggest that targeting innate lymphoid cell responses or directly targeting specific groups of commensal bacteria may be useful in the treatment of some chronic inflammatory diseases," adds Artis.
Journal reference:
Science
Provided by
University of Pennsylvania School of Medicine
-
Inner weapons against allergies: Gut bacteria control allergic diseases
Mar 25, 2012 |
not rated yet |
0
-
Friend or Foe? Scientists Determine How the Intestine Keeps Us Safe From Microbial Invaders
Feb 21, 2007 |
not rated yet |
0
-
Biodiversity loss may cause increase in allergies and asthma
May 07, 2012 |
not rated yet |
0
-
DNA of good bacteria drives intestinal response to infection
Oct 02, 2008 |
not rated yet |
0
-
Researchers investigate cellular mechanisms leading to immune response in airway epithelium
Nov 23, 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
-
Why is zone 1 in liver more prone to ischemic injury?
4 hours ago
-
How can there be villous adenoma in colon, if there are no villi there
May 22, 2013
-
How can there be a term called "intestinal metaplasia" of stomach
May 21, 2013
-
Pressure-volume curve: Elastic Recoil Pressure don't make sense
May 18, 2013
-
If you became brain-dead, would you want them to pull the plug?
May 17, 2013
-
MRI bill question
May 15, 2013
- More from Physics Forums - Medical Sciences
More news stories
Researchers develop sperm-sorting design that may aid couples undergoing in vitro fertilization
(Medical Xpress)—According to the World Health Organization, approximately 70 million couples experience infertility worldwide. Current data suggests that nearly one third of infertility disorders are due ...
Medical research
3 minutes ago |
not rated yet |
0
Baby's life saved with groundbreaking 3-D printed device that restored his breathing
Every day, their baby stopped breathing, his collapsed bronchus blocking the crucial flow of air to his lungs. April and Bryan Gionfriddo watched helplessly, just praying that somehow the dire predictions ...
Medical research
15 hours ago |
5 / 5 (2) |
0
Research shows how immune system peacefully co-exists with 'good' bacteria
The human gut is loaded with commensal bacteria – "good" microbes that, among other functions, help the body digest food. The gastrointestinal tract contains literally trillions of such cells, and yet the ...
Medical research
19 hours ago |
5 / 5 (3) |
0
|
Slowing the aging process—only with antibiotics
Swiss scientists reveal the mechanism responsible for aging hidden deep within mitochondria—and dramatically slow it down in worms by administering antibiotics to the young.
Medical research
19 hours ago |
4.9 / 5 (10) |
1
|
How healthy are you for your age?
On May 22, JoVE will publish details of a technique to measure the health of human genetic material in relation to a patient's age. The method is demonstrated by the laboratory of Dr. Gil Atzmon at New York's Albert Einste ...
Medical research
22 hours ago |
not rated yet |
0
Researchers find possible 'master switch' in deadly brain cancer
(Medical Xpress)—Researchers at the University of Virginia School of Medicine have identified a promising target for treating glioblastoma, one that appears to avoid many of the obstacles that typically frustrate efforts ...
Depression linked to telomere enzyme, aging, chronic disease
(Medical Xpress)—The first symptoms of major depression may be behavioral, but the common mental illness is based in biology—and not limited to the brain.
Vaccine blackjack: IL-21 critical to fight against viral infections
(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.
Fast-acting mothers' milk for healthier babies
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.
Non-Hodgkin lymphoma survival doubles since early 1970s
More than half of patients diagnosed with Non-Hodgkin Lymphoma (NHL) are now surviving the disease thanks to improved diagnosis and treatment, according to a new report1 from Cancer Research UK.
Air travel during pregnancy poses no significant risk, say experts
(Medical Xpress)—There is no significant risk directly associated with air travel during pregnancy, even at advanced gestation, says report by the University of Liverpool.
Jun 06, 2012
Rank: not rated yet