Asthma and Bacteria: Exposure May Help Body Beef Up Immunity, Study Says
The research was done in mice, but it supports the “hygiene hypothesis”: the idea that bacteria are needed to shape a healthy immune system, and that our bacteria-fearing lifestyles are increasing levels of asthma, allergy and other autoimmune diseases.
In the study, which was published in the journal Science, the researchers compared normal mice with mice that were raised in special germ-free environments. They found high levels of special white blood cells called invariant natural killer T cells (iNKT) in the lungs and intestines of the germ-free mice.
These iNKT cells release proteins that cause inflammation and attract more inflammatory white blood cells. Inflammation plays an important role in many autoimmune diseases, and iNKT cells are known to be an active ingredient in asthma, which is in the lungs, and ulcerative colitis, an inflammatory disease of the bowel.
Even when exposed to normal bacteria later in life, the germ-free mice still had abnormally high levels of iNKT cells and diseased lungs and intestines. This indicated that an “immune priming event” happens very early in life and is essential for the proper formation of the immune system, the researchers said.