Great journal club by @basbees on this paper by @ShikaRamanan et al. https://doi.org/10.1016/j.cell.2020.04.030

Multiple results: 1/n

1) Cross-fostering experiments (did I mention I these?!) show immune phenotype is vertically transferred through MILK (not genetics, epigenetics or microbes)

2. The 'active ingredient' in mother's milk seems to be IgA, which coats bacteria in the offspring's gut, impacting how these microbes program the developing immune system.

3. This impacts how the offspring produce their own IgA for the REST OF THEIR LIVES! ( #DOHAD, anyone?) 2/n

4. In daughters, this impacts how much IgA is present in the milk they will later feed to THEIR daughters. Therefore the effect of IgA received in mother's milk is TRANSGENERATIONAL! 3/n

(Shown beautifully in these experiments & figures)

5. This lifelong/transgenerational programming of the immune system through lactation occurs during a very EARLY & SHORT POSTNATAL window (first ~0-7 days of lactation). Mice lactate for 21 days. 4/n

6. Super cool 'photocovertible reporter mouse' technology used to show IgA-producing immune cells migrate from maternal gut to mammary gland during late pregnancy! AMAZING! 5/n

7. Authors infer: lack of 'lactational programming' in recent generations of formula-fed babies (mothers & grandmothers of current generation) could be contributing to the epidemic of #allergies & autoimmune diseases, which happened too rapidly to be explained by genetics 6/n

A great quote from the authors to end:

"We report a novel mode of transmission of maternal factors via the entero-mammary axis that influences
colonic Treg differentiation & function and sets the
immunoregulatory tone in the intestine THROUGH GENERATIONS"

#LactationIsAmazing