A man with gray hair .
(photo credit: INGIMAGE)
Chronic stress or a serious illness has been known to suddenly turn some people’s hair gray. A study published in the open access journal Biology offers insights into why this occurs.
Working on mice, researchers at the US National Institutes of Health and the University of Alabama in Birmingham have discovered a connection between the genes that contribute to hair color and the genes that notify our bodies of a pathogenic infection.
The team’s continued research may explain why some people experience premature gray hair early in life.
When a body is under attack from a virus or bacteria, the innate immune system starts to defend the body. Since all cells have the ability to detect foreign invaders, they respond by producing signaling molecules called interferons, which tell other cells to take action by turning on the expression of genes that inhibit viral replication, activate immune effector cells and increase host defenses.
The connection between hair pigmentation and innate immune regulation was initially a bit surprising, said biology professor Melissa Harris, the main author. “Genomic tools allow us to assess how all of the genes within our genome change their expression under different conditions, and sometimes they change in ways that we don’t anticipate. We are interested in genes that affect how our stem cells are maintained over time. We like to study gray hair because it’s an easy read-out of melanocyte stem cell dysfunction” that produce and deposit pigment in the hair shaft, she added.
In this case, an unexpected link was found between gray hair, the transcription factor MITF and innate immunity. While MITF is best known for regulating the many functions within melanocytes, it was also found to keep the melanocytes’ interferon response in check. If MITF’s control of the interferon response is lost in melanocyte stem cells, hair turns gray. Furthermore, if innate immune signaling is artificially activated in mice that are predisposed to getting gray hair, more hairs turn gray.
“Genes that control pigment in hair and skin may also work to control the innate immune system,” said Dr. William Pavan, study co-author and chief of the National Institute of Health’s genetic disease research branch. “These results may enhance our understanding of hair graying.
More importantly, discovering this connection will help us understand pigmentation diseases with innate immune system involvement like vitiligo,” in which patches of skin become white.