Antimicrobial found to calm inflamed gut in mice

November 1, 2016 by Bob Yirka, Medical Xpress report
Credit: Martha Sexton/public domain

(Medical Xpress)—A team of researchers with the University of California has found that introducing a type of antimicrobial protein called a microcin into the guts of mice with inflamed bowels caused a reduction in the degree of inflammation. In their paper published in the journal Nature, the team describes their study of the use of the protein in mice and their evidence that microcins intercede in the relationship between different types of bacteria in the gut.

Over the past several decades, scientists have made a lot of progress in better understanding the factors that lead to which covers a host of gut ailments, from Crohn's disease to colitis. Most of them, they believe, are due to harmful gut bacteria multiplying and pushing out . In this new effort, the team of researchers was studying small proteins called microcins, which are secreted by and serve as a means for striking back when pushed by . They conducted a study to determine if introducing the protein into the guts of mice with IBS would have a positive impact—prior work in the lab had suggested it might.

In the study, the researchers caused several mice to have IBS, then separated them into groups—some received doses of a type of E. coli that produces microcin, another group received another strain of E. coli that does not produce the protein while a third group got a dose of diarrhea-producing Salmonella enterica and a fourth got a dose of E. coli that is suspected to play a role in causing Crohn's disease in humans.

After waiting to see what might happen, the team found that the E. coli with the probiotic reproduced rapidly enough to push out the harmful bacteria that was causing the IBS in the mice—that in turn led to a reduction in inflammation. The team also found that the antimicrobial also caused a reduction in Salmonella enterica numbers in infected mice.

The researchers suggest that introducing microcin-producing bacteria to the gut of people suffering from IBS might someday be a realistic treatment for those afflicted, noting that such therapies could offer a way forward in overcoming problems associated with antibiotic resistance.

Explore further: Disease-causing gut bacteria common in children

More information: Martina Sassone-Corsi et al. Microcins mediate competition among Enterobacteriaceae in the inflamed gut, Nature (2016). DOI: 10.1038/nature20557

The Enterobacteriaceae are Gram-negative bacteria and include commensal organisms as well as primary and opportunistic pathogens that are among the leading causes of morbidity and mortality worldwide. Although Enterobacteriaceae often comprise less than 1% of a healthy intestine's microbiota1, some of these organisms can bloom in the inflamed gut2,3,4,5; indeed, expansion of enterobacteria is a hallmark of microbial imbalance known as "dysbiosis"6. Microcins are small secreted proteins that possess antimicrobial activity in vitro7,8, but whose role in vivo has been unclear. Here we demonstrate that microcins enable the probiotic bacterium Escherichia coli Nissle 1917 (EcN) to limit expansion of competing Enterobacteriaceae (including pathogens and pathobionts) during intestinal inflammation. Microcin-producing EcN limited growth of competitors in the inflamed intestine, including commensal E. coli, adherent-invasive E. coli, and the related pathogen Salmonella enterica. Moreover, only therapeutic administration of the wild-type, microcin-producing EcN to mice previously infected with S. enterica substantially reduced intestinal colonization of the pathogen. Our work provides the first evidence that microcins mediate inter- and intra-species competition among the Enterobacteriaceae in the inflamed gut. Moreover, we show that microcins can be narrow-spectrum therapeutics to inhibit enteric pathogens and reduce enterobacterial blooms.

Related Stories

Disease-causing gut bacteria common in children

October 4, 2016
A type of bacteria, which can cause diarrhea and inhibit growth in children in developing countries, has been found in 14% of a sample of children in an industrialized country. However, the children had only mild gastrointestinal ...

Gut microbiome of mother found to impact immunity of mice pups

March 18, 2016
(Medical Xpress)—A team of researchers from Switzerland and Germany has found that the gut microbiome of a pregnant mouse can have an impact on the development of the immune system in the pups she delivers. In their paper ...

Researchers identify protein critical in causing chronic urinary tract infections

September 22, 2016
Researchers have identified a potential way to prevent chronic urinary tract infections (UTIs). Their research points to a key protein that bacteria use to latch onto the bladder and cause UTIs, according to scientists at ...

Relationship between genes that make cells deaf to messages from good gut bacteria and OMVs identified

May 6, 2016
(Medical Xpress)—A team of researchers from several instantiations in the U.S. has found a connection between two defective genes in humans and the messages that are sent from a type of good bacteria and Irritable Bowel ...

Food-poisoning bacteria may be behind Crohn's disease

October 19, 2016
People who retain a particular bacterium in their gut after a bout of food poisoning may be at an increased risk of developing Crohn's disease later in life, according to a new study led by researchers at McMaster University.

Recommended for you

The complicated biology of garlic

April 26, 2018
Researchers today generally agree that eating garlic, used for thousands of years to treat human disease, can reduce the risk of developing certain kinds of cancers, cardiovascular disease, and type 2 diabetes. Nevertheless, ...

CRISPR-based diagnostic SHERLOCK optimized for rapid use during viral outbreaks

April 26, 2018
In a paper published today in Science, researchers at Broad Institute of MIT and Harvard report a new tool that engineers the CRISPR-based diagnostic SHERLOCK for rapid outbreak response. The updates to SHERLOCK, which was ...

Too liberal use of oxygen increases risk of death in acutely ill adult patients

April 26, 2018
McMaster University researchers have found there is such a thing as too much oxygen for acutely ill adults.

Noninvasive brain tumor biopsy on the horizon

April 26, 2018
Taking a biopsy of a brain tumor is a complicated and invasive surgical process, but a team of researchers at Washington University in St. Louis is developing a way that allows them to detect tumor biomarkers through a simple ...

Lab-on-a-chip delivers critical immunity data for vulnerable populations

April 25, 2018
For millions of displaced people around the world—many of them refugees, living in temporary shelters under crowded conditions—an outbreak of disease is devastating. Each year, the measles virus kills more than 134,000 ...

Want new medicines? You need fundamental research

April 25, 2018
Would we be wise to prioritize "shovel-ready" science over curiosity-driven, fundamental research programs? Would that set the stage for the discovery of more new medicines over the long term?

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Nov 01, 2016
Mr. Yirka: Have greatly appreciated your writing over the years, but Crohn's and colitis are classified as Inflammatory Bowel Disease (IBD), not Irritable Bowel Syndrome (IBS). IBD can be quite severe - even life threatening. By contrast, people suffering from IBS might wish they were dead but from a medical perspective it is much less severe.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.