Scientists Explain One Possible Reason Why Hair Turns Gray

Hair turning gray can be a sign of a virus and activity in the innate immune system, says a study from the University of Alabama at Birmingham.

Scientists from the UAB studied melanocytes in mice predisposed to gray fur and discovered an interesting connection between hair pigmentation and virus prevention.

MITF Controls Both Hair Color And Immune System

According to a report from UAB, melanocyte produces melanin, which gives the hair color as well as the eyes and skin. Melanocyte stem cells produces melanocytes when old hairs fall out and new hairs grow. The loss of melanocyte and melanocyte stem cells will result in non-pigmented — or gray — hair.

Melissa Harris, Ph.D., corresponding author and assistant professor in the UAB College of Arts and Sciences Department of Biology, says the researchers assessed mouse models of hair graying using current genomic tools to explore the behavior of melanocyte stem cell biology.

"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," she explains.

The MITF gene tells the melanocytes to produce melanin, but the researchers found that it also controls the genes that release interferons. Interferons, which are part of the innate immune system, are proteins that help fight off virus.

In their experiments in mice predisposed to graying, Harris and her team discovered that too much MITF — whether through a genetic mechanism or exposure to virus — result in a significant loss of melanocytes and melanocyte stem cells, leading to the growth of non-pigmented gray hair.

Findings Can Help Explain Early Graying, Pigmentation Diseases

"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 suggests, indicating a possible explanation for gray hair at an early age.

She cautions that the presence of gray hair alone is not a definitive indication of a viral infection, since there are a lot of ways to induce gray hair in mice.

"However, everybody gets viral infections, especially during flu season. But we don't see a huge prevalence of people getting sudden, premature gray hair," she points out in Gizmodo. "This suggests to me that if there is a predisposition in humans for susceptibility to innate immune-related hair graying, it may not be that common."

Unless, Harris says, it's simply a matter of most humans being better in using dyes in their hair.

Despite the limitations of the research, especially when it is translated to humans, William Pavan, coauthor and chief of the Genetic Disease Research Branch at the NIH's National Human Genome Research Institute, tells Newsweek that it can enhance scientists' knowledge of gray hair.

"More importantly, discovering this connection will help us understand pigmentation diseases with innate immune system involvement like vitiligo," he adds.

The study is published in the journal PLOS Biology.