Gray hair
Researchers at the National Institutes of health and the University
of Alabama, Birmingham offered insights into why some people’s hair may
turn gray in response to a serious illness or chronic stress.
A new study on mice, published in the open access journal PLOS
Biology discovered a connection between the genes that contribute to
hair colour and the genes that notify our bodies of a pathogenic
infection.
According to the researchers, when a body is under attack from a
virus or bacteria, the innate immune system detects them and responds by
producing signaling molecules called interferons.
Interferons signal to other cells to take action by turning on the
expression of genes that inhibit viral replication, activate immune
effector cells, and increase host defences.
Melissa Harris, the lead author and assistant professor within the
Department of Biology at UAB found a connection between hair
pigmentation and innate immune regulation.
In this study, an unexpected link was found between gray hair, the
transcription factor MITF or Melanogenesis Associated Transcription
Factor, and innate immunity.
MITF is best known for its role in regulating the many functions
within melanocytes. The researchers found that MITF also serves to keep
the melanocytes’ interferon response in check.
Harris said melanocyte stem cells were essential to hair colour as
they produced the melanocytes that were responsible for making and
depositing pigment into the hair shaft.
They found that if MITF’s control of the interferon response was lost in melanocyte stem cells, hair-graying resulted.
Furthermore, if innate immune signaling is artificially activated
in mice that are predisposed for getting gray hair, increased numbers of
gray hairs are also produced.
“This new discovery suggests that genes that control pigment in
hair and skin also work to control the innate immune system,” said
William Pavan, study co-author and chief of the Genetic Disease Research
Branch at National Human Genome Research Institute under National
Institute of Health.
“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,” said Paven.
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