Graying of Hair Linked to Dysregulated Immune System
Hair pigmentation over the course of a lifetime depends on melanocyte stem cells that reside in the hair follicle. Throughout the lifecycle of our hair, melanocyte stem cells function as a reservoir for the melanocytes that produce the pigment that renders our hair color. And the loss of these stem cells leads to the graying of hair.
Now, a team of NIH researchers along with their counterparts at the University of Alabama, Birmingham, have put forward an investigation offering insights into graying of hair in response to other external factors such as stress or immune system reactions.
“Our research looks primarily at how stem cells are affected by age,” said Melissa Harris, Ph.D., corresponding author and assistant professor in the UAB College of Arts and Sciences Department of Biology. “Using current genomic tools, we are able to look at the whole genome to gain a better understanding of which genes are expressed and when, and this allows us to better address the question of why we age the way we do. Hair-graying and melanocyte stem cells make up the models we use to study this process.”
“Evaluating mouse models of hair-graying using genomic tools can reveal key aspects of melanocyte stem cell biology,” said Harris. “Using this approach, we discovered a novel role for the melanogenesis-associated transcription factor, or MITF, in repressing the expression of innate immune genes within cells of the melanocyte lineage in mice.”
These animal models also allowed the team to discover how artificial elevation of the innate immune response either through a genetic mechanism or through virus exposure mimics results in significant melanocyte and melanocyte stem cell loss and leads to the elevated production of non-pigmented aka gray hairs.
Also, another interesting find involves the functioning of the interferons’ signalling pathway usually triggered by infected cells that was found to lead to the loss of melanocytes and melanocyte stem cells when increased in frequency.
Harris speculates that this might be why some individuals acquire gray hair early in life. “Perhaps, in an individual who is healthy yet predisposed for gray hair, getting an everyday viral infection is just enough to cause the decline of their melanocytes and melanocyte stem cells leading to premature gray hair,” Harris said.