Gut pathogens thrive on body's tissue-repair mechanism

September 16, 2016 by Carole Gan, UC Davis
Andreas Bäumler and his team discovered how pathogens manipulate the intestinal environment to favor their own growth. Credit: UC Davis

Why do some foodborne bacteria make us sick? A paper published Sept. 16 in the journal Science has found that pathogens in the intestinal tract cause harm because they benefit from immune system responses designed to repair the very damage to the intestinal lining caused by the bacteria in the first place.

"The finding is important because it explains how some enteric pathogens can manipulate mammalian cells to get the oxygen they need to breathe," said Andreas Bäumler, a professor of medical microbiology and immunology at UC Davis School of Medicine and lead author of the study. "It also offers new insight into developing strategies targeting the metabolism of the intestinal lining to prevent the expansion of harmful bacteria in the gut, a situation that is exacerbated by the overuse of antibiotics."

A healthy large intestine is mostly free of oxygen, and the beneficial microbes residing there thrive in this anaerobic environment. In contrast, enteric pathogens, such as Escherichia coli in humans or Citrobacter rodentium in mice, need oxygen to survive.

Bäumler's team discovered how these pathogens change the gut environment to favor their own growth.

"Enteric pathogens deploy virulence factors that damage the intestinal lining and cause diarrhea," Bäumler said. "To repair the damage, the body accelerates the division of epithelial cells that form the intestinal lining, which brings immature cells to the mucosal surface. These new cells contain more oxygen and wind up increasing oxygen levels in the large bowel, creating an environment that allows gut pathogens like E. coli to outcompete the anaerobic-loving resident microbes."

Bäumler's research has important implications for developing new treatment strategies that target factors that compromise the intestinal-lining function or bolster microbiota composition to offer either resistance or assistance to invading pathogens.

"The rise of antibiotic-resistant strains of bacteria has become a major public health threat worldwide, Bäumler said. "As more bacterial strains do not respond to the drugs designed to kill them, the advances made in treating infectious diseases over the last 50 years are in jeopardy."

This year, the Centers for Disease Control and Prevention identified three drug-resistant organisms – Clostridium difficile, Carbapenem enterobacteriaceae and Neisseria gonorrhoeae – as requiring urgent attention, and in May, a report commissioned by the UK government predicted that by 2050 antimicrobial-resistant infections could claim 10 million lives a year and cost up to $100 trillion from the global economy.

Understanding how gut manipulate the body's natural defense mechanisms to grab hold and contribute to abnormal states within and beyond the GI tract is a burgeoning area of research at UC Davis. Scientists from schools and colleges across the campus are investigating antibiotic resistance as well as the influence that gut-flora imbalances have on many conditions, including brain health and behavior, obesity, , , GI cancers, cardiovascular disease, , autism, arthritis and asthma.

Explore further: Antibiotics allow gut pathogens to 'breathe'

More information: C. A. Lopez et al. Virulence factors enhance Citrobacter rodentium expansion through aerobic respiration, Science (2016). DOI: 10.1126/science.aag3042

Related Stories

Antibiotics allow gut pathogens to 'breathe'

May 2, 2016
Antibiotics are essential for fighting bacterial infection, but, paradoxically, they can also make the body more prone to infection and diarrhea.

Antibiotics increase availability of nutrients in the gut, enabling growth of pathogens

June 15, 2016
Research led by Andreas Bäumler, professor of medical immunology and microbiology at UC Davis Health System, has identified a new mechanism explaining how antibiotics change the gut microbiota, increasing nutrients that ...

Scientists find key to growth of 'bad' bacteria in inflammatory bowel disease

February 7, 2013
(Medical Xpress)—Scientists have long puzzled over why "bad" bacteria such as E. coli can thrive in the guts of those with inflammatory bowel disease (IBD), causing serious diarrhea. Now UC Davis researchers have discovered ...

Good gut relationships key in defence against pathogens

June 29, 2016
Fighting infection in the gut relies on a dynamic relationship between the cells that line gut walls and microbiota – the hundreds of different bacteria that co-exist within the human body without causing harm.

How to achieve a well-balanced gut

August 8, 2013
Creating an environment that nurtures the trillions of beneficial microbes in our gut and, at the same time, protects us against invasion by food-borne pathogens is a challenge. A study published on August 8 in PLOS Pathogens ...

Study looks at the influence of fat when gut bacteria is reduced by antibioticsm

September 8, 2016
A study led by University of Cincinnati (UC) lipid metabolism researchers lends additional insight into how bacteria in the gut, or lack thereof, influences intestinal mast cells (MMC) activation and perhaps fat absorption. ...

Recommended for you

Long-term estrogen therapy changes microbial activity in the gut, study finds

June 20, 2018
Long-term therapy with estrogen and bazedoxifene alters the microbial composition and activity in the gut, affecting how estrogen is metabolized, a new study in mice found.

Researchers use AI to improve mammogram interpretation

June 20, 2018
In an effort to reduce errors in the analyses of diagnostic images by health professionals, a team of researchers from the Department of Energy's Oak Ridge National Laboratory has improved understanding of the cognitive processes ...

Are you sticking to your diet? Scientists may be able to tell from a blood sample

June 19, 2018
An analysis of small molecules called "metabolites" in a blood sample may be used to determine whether a person is following a prescribed diet, scientists at Johns Hopkins Bloomberg School of Public Health have shown.

Everything big data claims to know about you could be wrong

June 19, 2018
When it comes to understanding what makes people tick—and get sick—medical science has long assumed that the bigger the sample of human subjects, the better. But new research led by UC Berkeley suggests this big-data ...

Diagnosing and treating disorders of early sex development

June 19, 2018
Diagnosing, advising on and treating disorders of early sex development represent a huge medical challenge, both for those affected and for treating physicians. In contrast to the earlier view, DSD (Difference of Sex Development) ...

BPA can induce multigenerational effects on ability to communicate

June 18, 2018
Past studies have shown that biparental care of offspring can be affected negatively when females and males are exposed to bisphenol A (BPA); however, previous studies have not characterized how long-term effects of BPA exposure ...

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.