A pretty interesting, and telling, piece of research[i] came out just yesterday. In previous work, scientists have shown that babies who are allergic to cow’s milk have different gut bacteria than non-allergic infants. The question asked by these University of Chicago researchers is: can the microbiota be protective against developing milk allergy?
Gut microbes from healthy human babies and from babies allergic to milk were transplanted into mice which had been raised in a sterile environment and already sensitized (producing antibodies) to milk proteins. They then exposed the rodents to milk. The microbiota from the healthy babies did indeed protect the rodents from developing an allergy. Those rodents given either no microbes, or the microbiota of allergic babies, developed anaphylaxis when given milk.
The scientists also analyzed the bacterial microbiota from the babies and found many differences between the allergic and non-allergic babies. The non-allergic bacteria included a species already known to be protective against the development of food allergy: Anaerostipes caccae. When transplanted alone into mice, it protected against the development of milk allergy. “Our findings demonstrate that intestinal bacteria are critical for regulating allergic responses to dietary antigens and suggest that interventions that modulate bacterial communities may be therapeutically relevant for food allergy.”[ii]
What I can’t figure out why some babies have the species while others do not. Do the mothers of the allergic babies also have milk allergy? Are they (the moms) lacking this bacterial species? Have the allergic babies been introduced to antibiotics early in life? Where the allergic babies born via c-section?
Anaerostipes caccae is a normal part of human gut flora but not available as a probiotic. I wonder if it will be sold commercially soon. Is treatment of deadly allergy with probiotics or fecal microbiota transplant in our near-term future?
[ii] Taylor Feehley, Catherine H. Plunkett, Riyue Bao, Sung Min Choi Hong, Elliot Culleen, Pedro Belda-Ferre, Evelyn Campbell, Rosita Aitoro, Rita Nocerino, Lorella Paparo, Jorge Andrade, Dionysios A. Antonopoulos, Roberto Berni Canani, Cathryn R. Nagler. Healthy infants harbor intestinal bacteria that protect against food allergy. Nature Medicine, 2019; DOI: 10.1038/s41591-018-0324-z