The microbiome of the lactating nipple-areolar complex is part of the skin's immunoregulatory system

The nipple-areolar complex microbiome forms part of the skin's immunoregulation system

The healthy nipple-areolar complex (NAC) epidermis forms a structural scaffold for the NAC microbiome. Skin microbiome contains bacteria, archaea, viruses, protozoa, fungi and mites. The microbiome is part of the skin’s immunoregulatory mechanism, and extends deep into the dermis. The microbiome not only keeps the skin healthy, but activates an immune response if there is a developing infection.

Surface lipids and antimicrobial peptides of intact skin also help to prevent entry of potentially harmful environmental substances and microorganisms.

The host immune system closely controls the composition of skin microbiomes, and this is the dominant influence. But skin microbiomes are also shaped dynamically by

• Age

• Diet

• Hormonal state

• Geographic location.

These factors effect the complex adaptive system of an individual's skin microbiome dynamically, unpredictably, and variably over time.

The NAC microbiome is part of the nipple’s living interface with the infant. The nipple and areolar skin, ducts, and infant’s mouth all interact as microbial niches, since microbes interact with tissue surfaces and ductal openings. The ecology of the nipple-areolar complex and infant mouth microbiomes interrelate.

The NAC microbiome contains biofilm

We would expect that the NAC microbiome includes biofilms, since microbes immobilize into biofilms when they attach to a surface. The skin is a radically different environment to the alveoli and lactiferous ducts which contain breast milk and its microbiome. The breast milk microbiome is most credibly hypothesised to be predominantly planktonic.

A biofilm may be just a few dozen bacteria, or hundreds of thousands of bacteria, and is necessary for skin health.

References

Sams-Dodd J, Sams-Dodd F. Time to abandon antimicrobial approaches in wound healing: a paradigm shift. Wounds: a compendium of clinical research and practice 2018;30(11):345-52.