Let Them Eat Dirt: How Clean Environments May Set Kids Up for Immune Problems.
With modern plumbing and hygiene, the number of nasty microbes we are exposed to has plummeted, while the rate of auto-immune diseases and allergies has shot up. Are those related?
Proponents of the hygiene hypothesis think so: our immune system is supposed to develop by encountering microbes, so being too clean throws it out of whack as the immune system overreacts to minor insults.
A new study found that mice raised germ-free had especially high numbers of invariant natural killer T cells (iNKT) in their colons and lungs—the mouse versions of inflammatory bowel disease and asthma, respectively. Most evidence supporting the hygiene hypothesis has just been in observed correlations, so this research that identifies a plausible molecular mechanism is good evidence for how over-cleanliness might cause immune dysfunction.
Interestingly, microbial exposure only affected immune system development during a critical period in childhood. Microbial exposure had no effect on the iNKT cells of adult germ-free mice, but it did restore iNKT levels to normal in the offspring of pregnant germ-free mice exposed just before birth.
No comments:
Post a Comment