Why we get diarrhea

June 14, 2017
In the absence of claudin-2, clearance of C. rodentium (red) is impaired and bacteria are able to invade the normally-protected colonic crypt lumen. F-actin (green) and DNA (blue). Credit: Turner laboratory at Brigham and Women's Hospital.

Researchers want to know: does diarrhea serve a purpose? Does it actually help clear the bacteria causing a gastrointestinal infection, or is it merely a symptom of disease that should be prevented as much as possible? In a new study from Brigham and Women's Hospital, investigators explore the immune mechanism that drives diarrhea, concluding that it does play a critical role in pathogen clearance in the early stages of infection. The new study, published today in Cell Host and Microbe, also uncovers a previously unrecognized role for interleukin-22, an immune system molecule, in the host's defense against infection.

"The hypothesis that diarrhea clears intestinal pathogens has been debated for centuries," said corresponding author Jerrold Turner, MD, PhD, of the BWH Departments of Pathology and Medicine. "Its impact on the progression of remains poorly understood. We sought to define the role of diarrhea and to see if preventing it might actually delay pathogen clearance and prolong disease."

To investigate, researchers used a mouse model infected with Citrobacter rodentium, the mouse equivalent of an E. coli . Using this model, they saw an increase in the permeability of the intestinal barrier within just two days of infection—well before inflammation and epithelial damage. In particular, they uncovered a critical role for interleukin-22 that in turn influences another molecule called claudin-2, previously known to be involved in causing diarrhea. They found that diarrhea resulting from the signaling of these two molecules helped promote pathogen clearance and limited disease severity.

Other investigators have proposed developing new therapeutics to inhibit claudin-2. However, Turner and colleagues explain that the activation of this pathway may be critical for combating an infection, particularly in the early stages of a disease. They conclude that is critical to enteric pathogen clearance, and that IL-22 may play a key role in host defense.

Explore further: Microbiologists discover how gut bacterial resources are hijacked to promote intestinal illnesses

More information: Cell Host and Microbe (2017). DOI: 10.1016/j.chom.2017.05.009

Related Stories

Microbiologists discover how gut bacterial resources are hijacked to promote intestinal illnesses

December 10, 2014
UT Southwestern Medical Center microbiologists have identified key bacteria in the gut whose resources are hijacked to spread harmful foodborne E. coli infections and other intestinal illnesses.

Study suggests how flu-related gastrointestinal flare-ups can be relieved while body continues to battle virus the lung

November 3, 2014
Flu infection has long-ranging effects beyond the lung that can wreak havoc in the gut and cause a dreaded symptom, diarrhea, according to a study published in The Journal of Experimental Medicine.

Researchers identify a potential new therapeutic target for E. coli infections

March 28, 2013
(Medical Xpress)—A new study by researchers at the Center for Modeling Immunity to Enteric Pathogens at Virginia Bioinformatics Institute provides novel insight into how an emerging strain of the diarrhea-causing bacteria ...

Controlling levels of specific gut bacteria could help prevent severe diarrhea

November 10, 2015
Everyone has suffered from it. It's ranged from mild to severe. It's a condition that's most-often described in a whisper.

Recommended for you

Novel approach to track HIV infection

August 18, 2017
Northwestern Medicine scientists have developed a novel method of tracking HIV infection, allowing the behavior of individual virions—infectious particles—to be connected to infectivity.

Faulty gene linked to obesity in adults

August 18, 2017
Groundbreaking new research linking obesity and metabolic dysfunction to a problem in the energy generators in cells has been published by researchers from the Harry Perkins Institute of Medical Research and The University ...

Two lung diseases killed 3.6 million in 2015: study

August 17, 2017
The two most common chronic lung diseases claimed 3.6 million lives worldwide in 2015, according to a tally published Thursday in The Lancet Respiratory Medicine.

New test differentiates between Lyme disease, similar illness

August 16, 2017
Lyme disease is the most commonly reported vector-borne illness in the United States. But it can be confused with similar conditions, including Southern Tick-Associated Rash Illness. A team of researchers led by Colorado ...

Addressing superbug resistance with phage therapy

August 16, 2017
International research involving a Monash biologist shows that bacteriophage therapy – a process whereby bacterial viruses attack and destroy specific strains of bacteria - can be used successfully to treat systemic, multidrug ...

Can previous exposure to west Nile alter the course of Zika?

August 15, 2017
West Nile virus is no stranger to the U.S.-Mexico border; thousands of people in the region have contracted the mosquito-borne virus in the past. But could this previous exposure affect how intensely Zika sickens someone ...

0 comments

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.