Mammary epithelium permeability during established lactation: associations with cytokine levels in human milk

The connections, or junctions, between the individual epithelial cells that form the mammary gland can be tight or loose, either restricting or allowing transfer of the components in blood to move to the inner space, or lumen, of the mammary gland. The tightness or looseness of the cell connections is referred to as permeability. The permeability of the mammary gland is important for milk production. Permeability is low during established lactation in a healthy breast, preventing most components in blood from easily moving between the cells to enter the lumen and milk. But how can we measure permeability during lactation?  By simply measuring the concentration of sodium in milk we can estimate the mammary epithelium permeability because low permeability limits the sodium ions in the blood from moving into the milk. Elevated mammary epithelium permeability may occur with stress and or infection. In this publication in Frontiers in Nutrition we determined the incidence of elevated mammary epithelium permeability in the milk of 162 women and asked whether permeability was associated with cytokines in milk, the chemical messengers of the immune system.  Click here to access the full publication.