Figure 9: Schematic representation of mechanism underlying the effect of maternal fibre intake on the development of asthma, both in the adult, and in offspring.

Fibre consumption leads to changes in the microbiota and SCFA production. Acetate enters the bloodstream and inhibits HDACs, leading to transcription of Foxp3. Foxp3 promotes Treg numbers and function, which suppress airway inflammation. During pregnancy, SCFAs such as acetate are capable of crossing the placenta, and influencing gene expression in the fetal lung, such as Nppa, which encodes ANP, a molecule implicated in epithelial biology and immune regulation. It is also likely that maternally transferred acetate affects Treg biology in the fetus.