In the past few decades, food allergies have been increasingly and mysteriously on the rise. A possible explanation lies with our gut bacteria, which have been reshaped by our soap-laden and antibiotics-laden lifestyles. A new study in mice adds intriguing evidence: one particular type of bacteria prevents sensitivity to peanuts.
Several years ago, Catherine Nagler of the University of Chicago found that mice whose gut bacteria have been killed off are more susceptible to food allergies. By giving young mice antibiotics, she could actually induce peanut sensitivity in the creatures. So we can mess up these mice, but can we fix them?
Indeed, Nagler's new study in the journal PNAS identifies a single class of bacteria that can prevent peanut sensitivity in these mice. Clostridia are a common and diverse class of bacteria in the gut. When Nagler's team injected Clostridia into the mouths and stomachs of peanut-sensitive mice, their sensitivity went away. A different type of bacteria called Bacteroides had no effect.
Perhaps most fascinating is how Clostridia stops peanut allergies. It somehow coaxes cells in the intestinal lining of the mice to produce a molecule called interleukin-22, which makes the lining less permeable. That means fewer molecules from the peanuts escape from the intestine into the blood to cause allergy problems.
It's easy, still, to think of our gut microbiome as something separate from us -- the "others" that live inside but somehow apart from us. But as this study shows, bacterial and human cells are in a complex dance together, and the line can begin to blur. [PNAS via Science]