Food allergies have risen dramatically in recent years, leading scientists to speculate about possible environmental factors. A recent study suggests that antibiotics may be destroying a key gut microbe — one that could be reintroduced into the body, to restore proper immune function.
Food allergies are definitely on the rise. According to the U.S. Centers for Disease Control, some 4% to 6% of children are now affected. There has been an 18% increase among children in the U.S. between 1997 and 2007 (and possibly as high as 50%). It's an alarming generational increase — one that's likely caused by environmental interventions of some sort.
Now, a new study by Cathryn Nagler and her colleagues has shown that changes to the trillions of bacteria that normally inhabit our gastrointestinal tract are profoundly influencing our allergic reactions to food. The researchers implicated one bacterial community in particular: Clostridia.
Writing in Science Magazine, Jennifer Couzin-Frankel explains:
In one of the latest efforts, Nagler's team first confirmed that mice given antibiotics early in life were far more susceptible to peanut sensitization, a model of human peanut allergy. Then, they introduced a solution containing Clostridia, a common class of bacteria that's naturally found in the mammalian gut, into the rodents' mouths and stomachs. The animals' food allergen sensitization disappeared, the team reports online today in the Proceedings of the National Academy of Sciences. When the scientists instead introduced another common kind of healthy bacteria, called Bacteroides, into similarly allergy-prone mice, they didn't see the same effect. Studying the rodents more carefully, the researchers determined that Clostridia were having a surprising effect on the mouse gut: Acting through certain immune cells, the bacteria helped keep peanut proteins that can cause allergic reactions out of the bloodstream. "The bacteria are maintaining the integrity of the [intestinal] barrier," Nagler says.
The research "opens up new territory," Blaser says. It "extends the frontier of how the microbiome is involved" in immune responses and the roles played by specific bacteria. (Blaser's group reported earlier this month in Cell that giving mice penicillin soon after birth changed their gut microbiome and made them much more likely to be obese as adults.)
The researchers, who have now filed for a patent application, are hoping to interrupt the allergy process by directly manipulating our microbiota. One way this could be done is by using a probiotic consisting of Clostridia. Nothing like this exists quite yet, but Nagler's work suggests that such an intervention may be possible.
Read Couzin-Frankel's entire article. And check out the entire study at PNAS: "Commensal bacteria protect against food allergen sensitization".
Top image CDC.