According to a paper published yesterday in Nature, stem cells residing in the skin retain long-lasting memories of inflammation-provoking events, prompting the skin to heal faster from subsequent injury.
"By enhancing responsiveness to inflammation, these memories help the skin maintain its integrity, a feature that is beneficial in healing wounds after an injury," says Elaine Fuchs, a professor at The Rockefeller University and lead author of the study. "This memory may also have detrimental effects, however, such as contributing to the relapse of certain inflammatory disorders such as psoriasis."
The team performed a series experiments in mice revealing that wounds close more than twice as fast in skin that has already experienced inflammation. This effect lasted in the mouse models even if the damage had occurred as long as six months earlier.
Further experiments into the mechanisms behind this observation showed that inflammation can rewire cells to trigger a process that physically opens up distinct sites within the cell’s chromosomes allowing certain genes to be accessible for activation. Some such sites can remain open long after the skin has recovered. An increase of expression in the AIM2 gene, which is associated with inflammasome activation, appeared to explain the heightened ability for repair following damage.
The implications for these findings could be far reaching, potentially explaining recurring reactions that happen in autoimmune diseases like psoriasis or other disorders involving epithelial cells, such as gut and bowel disorders.
Image: Stem cells (green) migrate into a three-day-old wound to repair it. Image courtesy of the Laboratory of Mammalian Cell Biology and Development/The Rockefeller University.