Featured Research

from universities, journals, and other organizations

TB lung infection causes changes in the diversity of gut bacteria in mice

Date:
May 13, 2014
Source:
Johns Hopkins Medicine
Summary:
A tuberculosis (TB) infection in the lungs triggers immune system signaling to the gut that temporarily decreases the diversity of bacteria in that part of the digestive tract, evidence shows. "We often think of each part of the mucosal immune system, such as the lungs and gut, to be separated," the lead investigator notes. "However, the fact that an aerosol infection causes such rapid changes in the gut suggests that the various parts of the mucosal system throughout the body actually function in some way like a single organ."

Johns Hopkins researchers have found evidence in mice that a tuberculosis (TB) infection in the lungs triggers immune system signaling to the gut that temporarily decreases the diversity of bacteria in that part of the digestive tract.

The Johns Hopkins researchers showed that this decrease in diversity of gut bacteria as measured in fecal samples happened quickly -- within six days after mice were exposed to an aerosol mixture of M. tuberculosis, the TB bacteria. This prompt shift in diversity, they say, suggests that the immune system is attacking the gut bacteria, decreasing the overall diversity by causing certain bacteria to outgrow others in the gut.

The finding was also replicated using a different strain of the TB microbe, according to a report on the work in the May 12 issue of the online journal PLOS One.

Study leader Kathryn Winglee, a Ph.D. student working at the Johns Hopkins Center for Tuberculosis Research, says the finding is important, because it could lead to improved diagnosis of TB, a disease that infects one-third of the world's population and in 2010 caused 1.4 million deaths.

"The fact that the bacterial populations change in the gut means that we can begin to use this observation for TB diagnosis," Winglee says. "TB diagnosis is currently challenging, but a simple stool sample test that detects changes in the diversity of gut bacteria after TB infection in the lung might improve diagnosis."

The finding also adds to growing evidence that the various parts of the immune system found in mucous membranes throughout the body interact as a "global" organ rather than work as separate, individual sites of immune function. Mucous membranes are the moist linings of areas of the body exposed to the environment, such as the nostrils, mouth, lungs, genitals and intestinal tract. These membranes form a protective barrier against infection and contain immune system cells.

Gut microbes have a complex relationship with the immune system, according to Winglee. For example, individuals with arthritis, type 2 diabetes, asthma and certain other diseases have specific changes in the populations of their fecal bacteria compared to healthy people, she explains. "However, there have been very few studies focused on changes in gut bacteria in response to TB infection, especially in individuals whose gut bacterial diversity hasn't already been artificially affected by antibiotics," she says.

To study the effect of TB infection on gut bacteria, the researchers infected mice with M. tuberculosis using an aerosol machine that deposited the bacteria into their lungs. The researchers then studied the various populations of bacteria in the gut until the mice died. They compared samples collected after infection with gut bacteria samples taken before infection to identify the changes in populations. The researchers used genetic and statistical techniques to determine the numbers of species present and their abundance. TB infection caused a decrease in diversity of bacteria in the gut of all mice after infection, followed by a recovery in diversity, until death or one week prior to death.

For example, the relative abundance of a different species of bacteria belonging to two families -- higher-level groups that contain various species -- called Lachnospiraceae and Ruminococcaceae were higher before TB infection; they were also higher in uninfected mice. Other changes in populations of various species of gut bacteria also contributed to a decrease in diversity, as some bacteria become more prevalent while the population of others dwindled.

"Since TB bacteria were usually not found in the guts of the mice we studied, we believe that the changes in overall bacterial diversity are not caused by their presence there," Winglee says. "Instead, since the span of time when there was a minimum of diversity among bacterial populations that coincided with the most active immune response, we believe that it was the mucosal immune system that caused the shift in diversity."

Very little is known about the effects of specific gut microorganisms in humans, according to Winglee. So finding that there is a significant loss of diversity of gut bacteria with TB infection is a critical step in understanding some of the events that occur during this disease, as well as the role of the mucosal immune system, she says.

"We often think of each part of the mucosal immune system, such as the lungs and gut, to be separated," Winglee notes. "However, the fact that an aerosol infection causes such rapid changes in the gut suggests that the various parts of the mucosal system throughout the body actually function in some way like a single organ."


Story Source:

The above story is based on materials provided by Johns Hopkins Medicine. Note: Materials may be edited for content and length.


Journal Reference:

  1. Kathryn Winglee, Emiley Eloe-Fadrosh, Shashank Gupta, Haidan Guo, Claire Fraser, William Bishai. Aerosol Mycobacterium tuberculosis Infection Causes Rapid Loss of Diversity in Gut Microbiota. PLoS ONE, 2014; 9 (5): e97048 DOI: 10.1371/journal.pone.0097048

Cite This Page:

Johns Hopkins Medicine. "TB lung infection causes changes in the diversity of gut bacteria in mice." ScienceDaily. ScienceDaily, 13 May 2014. <www.sciencedaily.com/releases/2014/05/140513142030.htm>.
Johns Hopkins Medicine. (2014, May 13). TB lung infection causes changes in the diversity of gut bacteria in mice. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2014/05/140513142030.htm
Johns Hopkins Medicine. "TB lung infection causes changes in the diversity of gut bacteria in mice." ScienceDaily. www.sciencedaily.com/releases/2014/05/140513142030.htm (accessed September 2, 2014).

Share This




More Plants & Animals News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Snack Attack: Study Says Action Movies Make You Snack More

Snack Attack: Study Says Action Movies Make You Snack More

Newsy (Sep. 2, 2014) — You're more likely to gain weight while watching action flicks than you are watching other types of programming, says a new study published in JAMA. Video provided by Newsy
Powered by NewsLook.com
Get A Mortgage, Receive A Cat — Only In Russia

Get A Mortgage, Receive A Cat — Only In Russia

Newsy (Sep. 2, 2014) — The incentive is in keeping with a Russian superstition that it's good luck for a cat to be the first to cross the threshold of a new home. Video provided by Newsy
Powered by NewsLook.com
U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

Newsy (Sep. 2, 2014) — The U.N. says the problem is two-fold — quarantine zones and travel restrictions are limiting the movement of both people and food. Video provided by Newsy
Powered by NewsLook.com
Sharks Off the Menu and on the Tourist Trail in Palau

Sharks Off the Menu and on the Tourist Trail in Palau

AFP (Sep. 2, 2014) — Tourists in Palau clamour to dive with sharks thanks to a pioneering conservation initiative -- as the island nation plans to completely ban commercial fishing in its vast ocean territory. 01:15 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins