About Careers Internship MedBlogs Contact us
Medindia LOGIN REGISTER
Advertisement

Toxin Helps Identify Chronic Effects of E. Coli-induced Diarrhea

by Angela Mohan on December 10, 2020 at 12:03 PM
Font : A-A+

Toxin Helps Identify Chronic Effects of E. Coli-induced Diarrhea

Toxin produced by the bacterium E. coli changes gene expression in the cells that line the gut, inducing them to manufacture a protein that the bacterium then uses to attach to the intestinal wall.

The findings, published in Proceedings of the National Academy of Sciences, offer a clue to why recurrent but short-lived episodes of diarrhea could lead to long-term nutritional problems.

Advertisement


"There's more than meets the eye with this toxin," said senior author James M. Fleckenstein, MD, a professor of medicine and of molecular microbiology. "It is basically changing the surface of the intestine to benefit itself, probably ultimately to the detriment of the host.

Decades ago, people worked out how the toxin causes diarrhea, but until recently, nobody really had the tools to delve into what else this toxin might be doing. We're trying to put together the pieces of the puzzle to find out how toxin-producing E. coli might be driving malnutrition and other ripple effects of diarrhea."
Advertisement

Fleckenstein and first author Alaullah Sheikh, PhD, a postdoctoral researcher, study enterotoxigenic E. coli (ETEC), a toxin-producing strain of E. coli that is a common cause of severe, watery diarrhea. The bacterium's so-called heat-labile toxin causes ion channels on intestinal cells to open, triggering an outpouring of water and electrolytes into the digestive tract -- in other words, diarrhea.

Since oral rehydration therapy was invented in the 1970s, deaths from diarrhea have dropped by more than 80% worldwide. While invaluable at helping people survive a bout of diarrhea, the therapy does nothing to reduce the number of cases.

Worldwide, young children still develop diarrhea an average of three times a year, with the youngest and poorest children bearing the brunt of the caseload -- and of the long-term health consequences.

Fleckenstein and Sheikh speculated that ETEC's heat-labile toxin might be doing more than just causing acute diarrhea and dehydration. If so, it might explain the link between ETEC and malnutrition, stunting and other problems.

To find other ways the toxin affects the gut, the researchers grew human intestinal cells in a dish and treated the cells with the toxin. They found that the toxin activates a set of genes known as CEACAMs. One in particular -- CEACAM6 -- codes for a protein that is normally in cells of the small intestine at low levels.

Further experiments revealed that the toxin causes cells to produce more CEACAM6 protein, which the bacteria then uses to attach to intestinal cells and deliver even more toxin. Moreover, using intestinal biopsy specimens from people in Bangladesh infected with ETEC, the researchers showed that CEACAM6 expression increases in the small intestine during natural infection.

"CEACAM6 is expressed in what is called the brush border of the small intestine, which is where all your vitamins and nutrients get absorbed," Sheikh said.

"This is one of the first pieces of evidence that ETEC can change the intestinal surface. We don't yet know how long that lasts and what that means for people who are infected, but it stands to reason that damage to this part of the body could affect the ability to absorb nutrients."

Fleckenstein, Sheikh and colleagues are continuing to study the link between ETEC and malnutrition, stunting and other health consequences.

"We are trying in the lab to understand the role of ETEC and its toxins as they relate to nondiarrheal effects of ETEC infection, particularly in young children in developing countries," Fleckenstein said. "There's a lot of work to be done to explore how the toxins might be related to these long-term consequences of diarrhea."



Source: Eurekalert
Advertisement

Advertisement
News A-Z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
What's New on Medindia
Prevent Hacking of Medical Devices: FDA Sounds Alarm
Black Water: Benefits and Uses
World Hypertension Day 2022 - Measure Blood Pressure Accurately, Control It, Live Longer!
View all
Recommended Reading
News Archive
Date
Category
Advertisement
News Category

Medindia Newsletters Subscribe to our Free Newsletters!
Terms & Conditions and Privacy Policy.

More News on:
Detox Diet Cholera Botox Amoebic Dysentery Colo-rectal cancer - Management Crohns Disease Diarrhea Symptom Evaluation Norovirus Travelerīs Diarrhea Dehydration in Children / Pediatric Dehydration 

Most Popular on Medindia

Hearing Loss Calculator Accident and Trauma Care Blood - Sugar Chart Vent Forte (Theophylline) Pregnancy Confirmation Calculator Selfie Addiction Calculator Calculate Ideal Weight for Infants How to Reduce School Bag Weight - Simple Tips Indian Medical Journals Find a Doctor

Disclaimer - All information and content on this site are for information and educational purposes only. The information should not be used for either diagnosis or treatment or both for any health related problem or disease. Always seek the advice of a qualified physician for medical diagnosis and treatment. Full Disclaimer

© All Rights Reserved 1997 - 2022

This site uses cookies to deliver our services. By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Use