We acquire our first microbes from our mothers, during birth or even in utero.
According to researcher Susan Lynch: “Over our first years of life, our microbiomes rapidly diversify and these germs provide our developing selves with a library of microbes which train our immune system to tolerate their presence. This early microbial education, may explain why babies delivered vaginally are less likely than those born by cesarean section to acquire allergies or asthma in childhood. Without that early conditioning the immune system can mistake a harmless substance such as pollen or pet dander as being dangerous.
Such associations suggest that the microbiomes we cultivate as infants affect our health later in life. But how? Lynch’s research has begun to yield some answers. In a 2016 study, she showed that patterns in the composition of the gut microbiomes of 1-month-old babies could predict which kids were at a much higher risk of acquiring allergies by age 2 and asthma by age 4. The gut microbiomes of the high-risk infants were missing a wide range of anti-inflammatory molecules, she found.
In a subsequent paper, Lynch identified a molecule made by the high-risk infants’ gut bacteria that is responsible for the later emergence of allergies. Her team showed that the molecule travels through the blood to the airway, where it impairs immune cell activity, leading to inflammation.
Now there is hope—a product by Siolta Therapeutics is in development that will deliver a cocktail of live bacteria into the guts of newborns most at risk of allergies and asthma. The hope is that these bugs will start making the asthma-protective molecules that are underproduced by the babies’ native microbiomes.