Not all germs are created equal. Some invade the body and cause disease or harmful infections but others live peacefully in your intestines, helping your body run smoothly. Antibiotics can't tell the difference. They knock out good and harmful bacteria alike.
That's usually okay for people fending off bacterial infections, like the painful ones that can grow in your ear, but it might be a problem for fighting the flu. Researchers from Yale University say that when mice on antibiotics were infected with the flu virus, they had a harder time fighting off sickness than did mice that hadn't been taking antibiotics.
Helpful bacteria are called “commensal” bacteria — and you've got a lot of them. More than 1,000 different types of bacteria live in the human body. In the intestines, commensal bacteria help break down food . They can also prevent bad bacteria from launching an infection.
In earlier experiments, scientists had shown that commensal bacteria can help fend off bad bacteria in the intestines. But that's not the only place, say the Yale researchers. The scientists discovered that these friendly gut-dwelling germs can help the immune system find and fight invaders elsewhere in the body. When antibiotics knocked out the good bacteria in the mice intestines, the mice had trouble fighting off viral infections in their lungs.
This long-distance relationship shows that the good germs in the gut can make a difference all over the body, and that antibiotics may jeopardize those benefits. The gut bacteria help the immune system create a protein called interleukin-1 beta, or IL-1 beta. The body uses this molecule to fight off the flu and other viral infections.
When the scientists gave antibiotics to the mice, the antibiotics wiped out the good bacteria that made IL-1 beta. As a result, when those mice were given the flu, they had a harder time fighting the infection than did the mice that hadn't been given The scientists showed that antibiotics can wipe out important commensal bacteria, but a mystery remains. It’s not clear which bacteria are responsible for the IL-1 beta. But it’s possible to rule out some kinds.
“We know for sure that there are certain bacteria that can’t do it,” Akiko Iwasaki told Science News. Iwasaki, who led the study, is an immunologist at Yale. Immunologists study the body's immune system.
The mice had a hard time with the flu, but their immune systems still worked. Iwasaki and her colleagues found that even while on antibiotics, mice could stop an infection by the herpes virus. That's because the body doesn't need IL-1 beta to fight herpes.
The connection between the gut and the immune system could lead to new types of medicine. If scientists can find which bacteria help make IL-1 beta, for example, they might be able to find a way to boost production of those bacteria ― and thus boost the immune system at the same time.
The experiment is also a reminder: Next time you fight off the flu, thank your germs!
POWER WORDS (adapted from the New Oxford American Dictionary)
gut The intestines
bacteria Single-celled organisms that can live in soil, water and air, as well as inside and outside the human body. In the intestines, beneficial bacteria called commensal bacteria can help break down food and fight infection.
virus An organism that is made of genetic material surrounded by a protein shell. When a virus invades a host, it begins reproducing rapidly, causing infection.
proteins Large molecules that perform a wide variety of functions and are essential to life.
immunity The ability of a body to resist a particular infection.
immunology The branch of medicine and biology that focuses on immunity.
That's usually okay for people fending off bacterial infections, like the painful ones that can grow in your ear, but it might be a problem for fighting the flu. Researchers from Yale University say that when mice on antibiotics were infected with the flu virus, they had a harder time fighting off sickness than did mice that hadn't been taking antibiotics.
Helpful bacteria are called “commensal” bacteria — and you've got a lot of them. More than 1,000 different types of bacteria live in the human body. In the intestines, commensal bacteria help break down food . They can also prevent bad bacteria from launching an infection.
In earlier experiments, scientists had shown that commensal bacteria can help fend off bad bacteria in the intestines. But that's not the only place, say the Yale researchers. The scientists discovered that these friendly gut-dwelling germs can help the immune system find and fight invaders elsewhere in the body. When antibiotics knocked out the good bacteria in the mice intestines, the mice had trouble fighting off viral infections in their lungs.
This long-distance relationship shows that the good germs in the gut can make a difference all over the body, and that antibiotics may jeopardize those benefits. The gut bacteria help the immune system create a protein called interleukin-1 beta, or IL-1 beta. The body uses this molecule to fight off the flu and other viral infections.
When the scientists gave antibiotics to the mice, the antibiotics wiped out the good bacteria that made IL-1 beta. As a result, when those mice were given the flu, they had a harder time fighting the infection than did the mice that hadn't been given The scientists showed that antibiotics can wipe out important commensal bacteria, but a mystery remains. It’s not clear which bacteria are responsible for the IL-1 beta. But it’s possible to rule out some kinds.
“We know for sure that there are certain bacteria that can’t do it,” Akiko Iwasaki told Science News. Iwasaki, who led the study, is an immunologist at Yale. Immunologists study the body's immune system.
The mice had a hard time with the flu, but their immune systems still worked. Iwasaki and her colleagues found that even while on antibiotics, mice could stop an infection by the herpes virus. That's because the body doesn't need IL-1 beta to fight herpes.
The connection between the gut and the immune system could lead to new types of medicine. If scientists can find which bacteria help make IL-1 beta, for example, they might be able to find a way to boost production of those bacteria ― and thus boost the immune system at the same time.
The experiment is also a reminder: Next time you fight off the flu, thank your germs!
POWER WORDS (adapted from the New Oxford American Dictionary)
gut The intestines
bacteria Single-celled organisms that can live in soil, water and air, as well as inside and outside the human body. In the intestines, beneficial bacteria called commensal bacteria can help break down food and fight infection.
virus An organism that is made of genetic material surrounded by a protein shell. When a virus invades a host, it begins reproducing rapidly, causing infection.
proteins Large molecules that perform a wide variety of functions and are essential to life.
immunity The ability of a body to resist a particular infection.
immunology The branch of medicine and biology that focuses on immunity.
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