Most of us would agree that there is nothing good about the flu. Who would ever want to have the fever, body aches, runny nose and congestion that come with the flu? Scientists at Children’s Hospital Boston may have a different opinion. Their study suggests that getting the flu as a baby may help provide valuable immunity against certain kinds of asthma later in life.
The group of scientists has been studying what is known as the “hygiene hypothesis.” This idea suggests that there is a relationship between the reduced number of childhood infections thanks to vaccines and antibiotics and the increased number of children who are developing asthma and allergies as they grow older.
The scientists studied mice that were given the flu virus at a very young age. They report that the mice which had the flu by age 2 weeks seem to be protected against developing asthma. Having the flu at a later age seems to make the asthma symptoms worse. The scientists also discovered that young mice infected by the bacteria Helicobacter pylori (H. pylori), which is a common cause of gastrointestinal infections, also received the same protection against asthma.
"Some infections appear to result in important protective effects against asthma," said Dale Umetsu, MD, PhD, of Children's Division of Immunology, a senior author of the paper, and Professor of Pediatrics at Harvard Medical School. "But we certainly don't want to give people dangerous infections to prevent asthma. So if we can understand how infections prevent asthma, we may be able to replicate the good parts and avoid the bad parts of infection and develop new treatments for children to prevent asthma."
Researchers in this study focused on cells that are present in the immune system and are designed to jump into action quickly when there is an infection. They believe the flu helps protect against asthma by expanding immature NKT cells in the lungs which are part of the innate immune system. They believe that when the flu or H. pylori infections activate these cells early in life, it helps provide protection against asthma later in life.