Escherichia coli (E. coli) is usually associated with food poisoning, diarrhea, and, pneumonia. However, the E. coli strain Nissle has been found to protect the gut from harmful enterohemorrhagic E. coli (EHEC).
Nissle has been used as a probiotic for more than one hundred years and had recently been used to treat ulcerative colitis and other intestinal disorders. ulcerative colitis is an inflammatory bowel disease affecting the lining of the large intestine and the rectum.
Probiotics such as Nissle are beneficial for the digestive system. The good bacteria maintain gut health and help with digestive problems such as constipation.
Recently, scientists have also linked probiotics to mental health. A study in the British Medical Journal Nutrition Prevention & Health notes, 'As such, the effect that probiotics have on patients with [common mental disorders] may be twofold: they may directly improve depression in line with the observed findings of this review, and/or they might beneficially impact a patient's experience of their [common mental disorder] by alleviating additional comorbidities.'
Good E. Coli
A team from the University of Cincinnati experimented with good E. coli, the Nissle strain, to see if it could protect the intestine against harmful pathogens such as EHEC. In the laboratory, they created human intestinal organoids created from stem cells.
The intestine organoids were initially injected with Nissle and observed its harmless behavior. As expected, the epithelial barrier, or epithelial tissues that constantly renew and repair with the human body, remained undamaged.
Next, they injected separate organoids with harmful E. Coli, the EHEC, which produces the Shiga toxin. Almost immediately, the epithelial barrier in the organoids broke down.
After, new intestinal organoids were injected with Nissle followed by EHEC 12 hours later. Although EHEC managed to multiply effectively in the tissue, Nissle prevented the harmful E. Coli from breaking down the epithelial barrier. They also observed that the Nissle population decreased rapidly as they protected the organoid tissue.
Preventing Infections
The results repeated themselves when another set of organoids were pre-treated with Nissle and then given a dose of uropathogenic E. coli, a different strain associated with urinary tract infections. Molecular geneticist Alison Weiss said, 'basically, the Nissle was killed by the pathogenic bacteria, but it made the intestine able to withstand damage better.'
Weiss and the team believe that the probiotics can help prevent infections caused by harmful strains of E. Coli as it harnesses defense mechanisms within its own cell. However, since the Nissle populates declined when in contact with EHEC, its usefulness in treatment may be limited.
Weiss continues, 'It's really bad. My whole career, I've been interested in preventing pediatric pathogens. Once these kids get EHEC, all you can do is give them fluids and support them. There's nothing else we can do."
Using human intestinal organoids for these experiments has been a significant breakthrough, shared Weiss. Scientists are able to conduct more studies to understand many other species of bacteria and how they affect organoids.
Another advantage, she notes, is her preference for organoids over mice models. 'Mice are awful. They pee and bite and scratch," she said. "The little organoids don't complain at all."
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