Researchers at the University of British Columbia (UBC) and BC Children’s Hospital show that the sugar sialic acid, which makes up part of the protective intestinal mucus layer, fuels disease-causing bacteria in the gut. The findings could lead to a potential treatment target for intestinal bacterial infections
The findings are published in PNAS in an article titled, “Sialic acid plays a pivotal role in licensing Citrobacter rodentium’s transition from the intestinal lumen to a mucosal adherent niche.”
“Bacteria need to find a place in our intestines to take hold, establish, and expand, and then they need to overcome all the different defenses that normally protect our gut,” said Bruce Vallance, PhD, a professor in the department of pediatrics at UBC and investigator at BC Children’s Hospital. “In the future, we can potentially target this sugar, or how pathogens sense it, to prevent clinically important disease.”
In the study, researchers examined Citrobacter rodentium, an intestinal bacterial pathogen of mice that is used to model infections with human E. coli. The team discovered that the bacteria have genes involved in sialic acid consumption, and when these genes are removed, the bacteria’s growth is impaired.
“You start off with IBD, your microbes change, they start digging their way into the cells lining your gut, causing more inflammation, and that may be one reason why IBD becomes chronic,” said Vallance. “Specific nutrients such as sialic acid or other sugars might be Achilles heels for them in terms of things you could target to remove dangerous bacteria from the intestine.”
Vallance and his team are now examining the role other sugars in the gut may play in feeding pathogenic bacteria. They’re also looking for resident good bacteria (probiotics) that could outcompete the dangerous bacteria, stealing the sugars away from them.
“Basically, these accomplices cut the sugar off the mucus, and then either they hand it to the dangerous bacteria or the dangerous bacteria have come up with a way of stealing it from them,” he explained.
“In the past, our ancestors were constantly assaulted by dangerous bacteria,” said Vallance. “With the advent of more and more antibiotic resistance in bacteria, these bacterial infections are going to become a growing problem again. Without new antibiotics, we need to come up with novel ways to fight these bacteria, like starving them.”