Malnutrition And Growth-Stunting Caused By One E. Coli Strain That Plagues Many Poor Nations May Be Preventable Via Vaccines, New Research Found
According to the CDC, diarrhea was actually the third leading cause of death in 1900. And during the mid-twentieth century, this ailment claimed the lives of approximately 4.5 million children under the age of five every single year.
Nowadays, oral rehydration therapy has been lifesaving and has severely cut down the death rate. Unfortunately, though, this therapy does not protect against or prevent infection.
There are still millions of adolescents who live in low or middle-income countries that consistently suffer bouts of diarrhea.
And these episodes leave the body weakened and malnourished and can even result in stunted growth and the inability to fight off various infections.
So recently, researchers from the Washington University School of Medicine set out to study how exactly Escherichia coli– or E. coli– causes intestinal bacteria damage that can lead to malnutrition and stunted growth.
On top of that, they found that vaccinating against an E. coli-produced toxin protected mice- and could potentially protect humans– against intestinal damage.
“Ideally, we’d like to have a vaccine that prevents acute diarrhea, which still kills half a million children a year, and that also protects against long-term effects such as malnutrition, which is perhaps the bigger part of the problem now,” explained James M. Fleckenstein, the study’s senior author.
While E. coli is already a common cause of diarrhea throughout the world, there are different strains in the United States and other wealthy nations that usually do not carry the same toxins as strains in poorer countries.
So, Fleckenstein specifically studies one type of E.coli known as enterotoxigenic E. coli (ETEC)– which was named after the two toxins it produces, as well as the toxic effect this strain has on children.
michaeljung – stock.adobe.com – illustrative purposes only, not the actual people
In a 2020 study conducted by Fleckenstein, he found that ETEC’s toxins do much more than just push patients to take up residency in the bathroom.
Instead, one of the toxins– known as heat-labile toxin– actually impacts gene expression in the gut, which ultimately leads to more bacteria sticking to the intestinal wall.
And in the more recent Washington University study, it was discovered that the toxin even suppresses an entire group of genes that are related to the intestinal lining– in other words, where nutrients are absorbed.
This intestinal border is typically made up of microscopic projections that are tightly packed and resemble bristles on a brush– known as microvilli.
After the ETEC toxin was applied to clusters of human intestinal cells, though, this intestinal border just disintegrated.
“Instead of being nice and tight and upright with thousands of microvilli per cell, they are short, floppy and sparse, kind of like if you had plucked out most of the bristles and what was left was kind of raggedy,” detailed Alaullah Sheik, a co-leader of the study.
So, that alone would severely impact anybody’s ability to absorb nutrients. In addition to that discovery, though, the researchers also found that genes linked to the absorption of specific minerals and vitamins– such as zinc and vitamin B1– were also downregulated.
“That could explain some of the micronutrient deficiencies we see in children repeatedly exposed to these bacteria,” Sheik said.
And since children who live in poorer nations often suffer repeated bouts of diarrhea, the risk of growth stunting and malnutrition only increases with every single infection.
In turn, the researchers now believe that if the ETEC toxin is the issue, then an immune response that works to neutralize that toxin may be able to prevent long-term effects.
The team tested this theory by vaccinating nursing mouth mothers with the toxin– since it is not safe to immunize suckling mice themselves as they are too young.
And interestingly, they found that the nursing mothers produced antibodies that were then passed to their children via milk. These antibodies apparently worked in the infant mice, too, since they appeared healthy.
This discovery suggests that vaccination may be the next step in protecting children around the world from malnutrition-causing intestinal damage.
“This is an argument for developing a vaccine for this kind of E. coli,” underscored Fleckenstein.
“There are lifelong consequences of getting infected over and over in childhood. Vaccination combined with efforts to improve sanitation and access to clean water could protect children from the long-term effects and give them a better shot at long, healthy lives.”
To read the study’s complete findings, which have since been published in Nature Communications, visit the link here.
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