Breast milk is not just for feeding, it’s for teaching

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Transcript of “Breast milk is not just for feeding, it’s for teaching”

Moms are sending genetic messages to their baby’s immune system via their breast milk, they’re teaching it the ABCs, so that is knows exactly how to behave.

Breast milk is a whole lot more than just food………..one of the extra goodies, tucked inside are very short pieces of RNA, known as microRNA (miRNA).

Scientists have known about these tiny pieces of RNA for sometime, but until recently, they received very little attention, because it was assumed, that they were just cell “trash”. But, over the last few years, it has become increasingly clear, that these short pieces of RNA, which don’t actually code for anything, are part of an elaborate communication system.

Special messages

Cells are sending these little genetic messages to one another, wrapped inside membrane bound structures, called exosomes. The messages are designed to influence which genes are being turned on or off inside the cells that receive them, ultimately, allowing regulation of gene expression from a distance.

As scientists have learned more about this cell-cell exchange, it has become increasingly clear, these packages, are treasures not trash.

And these treasures are definitely part of the magic of breast milk.

Searching for buried treasure

A group of Japanese researchers, set about describing the microRNA profile of breast milk samples taken from 8 Japanese Moms. The milk samples were taken when the infants were between 4 days and 11 months old.

The scientists were able to confirm, miRNAs are present in human breast milk.

Using microarray analysis, they found 281 different miRNAs. They found slight variations between individual Moms, but found each Mom consistently produced the same set of miRNAs and the levels were highest in the first 6 months of breast feeding, tapering off there after.

Does the package get delivered ?

A quick calculation suggested there were around 13 million copies, per litre of one specific RNA molecule (miR-181a).

That sounds like a lot.

But, RNA molecules are not known for their persistence, they’re here today and gone tomorrow. Generally speaking, RNA molecules are quickly chopped into pieces, by a ubiquitous enzyme, RNase.

So, just because the treasure is being sent, does not mean it is being delivered ?

A resistant treasure

To test out, the tenacity of the breast milk microRNAs, the team subjected them to tough conditions.

They dipped them in RNase – but they survived.
They bathed them in acid, for an hour – but they persisted.
They froze them, then thawed them several times – and still they endured.

These results confirmed, these microRNA treasures are designed to be delivered, they are likely to survive the passage through the stomach, reaching the infant’s intestine and possibly, moving beyond the intestine, thanks to the immaturity of the infant gut. It is rather leaky….

Taking stock of the treasure

When the team analysed the composition of the 281 miRNAs, they found the dominant miRNAs in breast milk, were immune-related miRNAs.

I won’t bore you with the details…….

But overall, the miRNAs being sent to baby, are the ones involved in regulating T and B cell maturation and the innate immune response.

Suggesting…………………………Mom is teaching baby’s immune system, the ABCs.

A very important lesson

Immune systems that get this wrong, run into all sorts of problems – typically manifesting as some kind of auto-immune disease, such as asthma or allergy.

Baby’s that are breast fed are protected from these troubles.

Could mircoRNAs be one of the reasons ?

Possibly. Breast milk is definitely a treasure trove, so if you can breast feed.

MicroRNA as a new immune-regulatory agent in breast milk. Nobuyoshi Kosaka, Hirohisa Izumi, Kazunori Sekine, Takahiro Ochiya. Silence (2010) 1:7.

Milk: an exosomal microRNA transmitter promoting thymic regulatory T cell maturation preventing the development of atopy? Bodo C Melnik, Swen Malte John and Gerd Schmitz. Journal of Translational Medicine (2014) 12:43.