Have you ever wondered why when a child comes home from school with a stomach bug that threatens to sideline the whole family, some members of the family get sick while others go unscathed? Well, according to a Duke Health study a person’s resistance to certain germs, specifically E. coli bacteria, could come down to their very DNA.
Researchers came to this conclusion after exposing 30 healthy adults to enterotoxigenic Escherichia coli, one of the world’s leading causes of bacteria-induced diarrhea and a common cause of so-called “traveler’s diarrhea,” which often requires treatment with antibiotics.
To learn more about why some people get sick and others stay well, the researchers drew patients’ blood and looked for clues in their gene expression — the degree to which some genes are turned on or off. They noted the differences among the six patients with severe symptoms, and the six participants who showed no symptoms despite having been exposed to the bacteria.
What they found was that among the thousands of genes that distinguished the two groups, there were significant differences in the activity of 29 immune-related genes that could predict who would go on to become sick and those who would remain well, senior author Ephraim Tsalik, M.D., Ph.D., said in the article.
“Within each group, there were changes in the patients’ gene expression patterns happening throughout the experiment,” Tsalik added. “We found there were differences with the subjects that seemed to predict who would become sick. We interpreted those as signals that show an innate resistance to infection. There may be certain genetic traits that can increase or decrease your chances of being infected after exposure to a pathogen.”
Based on these results, the scientists hope to replicate the study with other types of infections, including viral and respiratory illnesses such as the flu.
“We have found a set of immune-related genes to focus on,” Tsalik said in the article. “Now if we can understand how the expression of these genes imparts this resistance and susceptibility, we might be able to offer new ways to boost your immune system to protect against prevalent infections such as E. coli or better predict who is at greatest risk of getting an infection.”
A household with children is the perfect example, Tsalik continued, who added that he has three children ages 11, 9 and 5, who often come home from school or sports practice bearing the newest cold or stomach bug.
“You have a natural experiment in that environment,” he said. “Our whole household gets exposed. I tend not to get sick and if I do, it’s pretty mild and might last a day. Meanwhile, my wife gets one cold after another. We’re discovering that among the factors that play a role in your resistance to infection — including the environment, stress levels, and gut bacteria — there is likely to be an innate biological explanation, too.”
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