Breast epithelia use Rac1 to hijack the job of immune phagocytes evading harmful inflammation.
Rac1 gene deletion in mammary gland epithelia reveals new roles in development and in long-term tissue function. The study published in Developmental Cell found that Rac1 is crucial both for the secretion of milk and its removal in the drying up period that follows. When milk is no longer required, Rac1 switches epithelial cell function from secretion to phagocytosis. Akhtar et al., found that the breast epithelia use Rac1 to evade harmful inflammatory phagocytes from the immune system by hijacking their job.
In the first few days after weaning, live breast epithelia engulf their dying neighbours and swallow all of the secretions, rapidly clearing the ducts from surplus milk and dead cells. The phagocyte-like breast epithelia then die themselves and these are subsequently cleared up by professional phagocytes from the immune system.
Nasreen Akhtar said “By doing the job themselves, the breast epithelia limit both the numbers and time of immune phagocyte infiltration which protects the tissue from becoming damaged”.
The study reveals that clearance after lactation is a crucial step for the gland to regenerate and produce milk in a future pregnancy and thereby maintain long-term tissue function.
The article published as Gold Open Access can be found at: authors.elsevier.com/sd/article/S1534580716305809
University of Sheffield press release: www.sheffield.ac.uk/news/nr/pac-man-protein-eats-dead-cells-that-could-help-fight-cancer-1.643585