Proceedings of the National Academy of Sciences

Health news

Bloody hell! Your Immune System works more, worse the diarrhoea

The Centres for Disease Control and Prevention estimates that EHEC causes about 95,000 illnesses in the United States each year. Of those, about 5 to 10 per cent become life-threatening and can cause the kidneys to shut down. DALLAS – May 23, 2020 – A type of E. coli bacteria that causes bloody diarrhoea uses an amino acid produced by the body in response to infection to intensify its symptoms, according to a new study from UT Southwestern scientists. The study, to be published this week in Proceedings of the National Academy of Sciences, is the first to identify the role of the arginine receptor (ArgR) in the progression of enterohemorrhagic E. coli O157:H7 (EHEC) infection. A deeper understanding of this relationship could lead to treatments other than the usual therapy for the illness – hydration. “We found that the bacteria provoke the host’s response and then they use an amino acid that the host makes as part of that response as a signal to increase infectivity,” says Vanessa Sperandio, Ph.D., professor of microbiology at UTSW and senior author of the study. The pathogen uses the host’s initial slight increase in arginine as a signal to inject a mix of virulence proteins into the cells lining the host’s colon, intensifying inflammation, the study found. “Usually when the arginine level increases, it’s a sign your immune system is working to clear the infection,” Sperandio says. “We find that the amino acid levels also rise when the host is being abused by the infection.” Sperandio studies the environment in the gut that is teeming with chemical messages. She is especially interested in EHEC, which can sicken people. Of the many strains of E. coli, most are harmless, including those that routinely live in the human intestinal tract. However, some kinds of E. coli, including EHEC, produce a toxin that can cause stomach cramps, diarrhoea (often bloody), and vomiting. EHEC is transmitted to humans primarily by eating contaminated foods, such as raw or undercooked ground meat products and raw milk, vegetables, and sprouts. The Centres for Disease Control and Prevention estimates that EHEC…