What causes gray hair besides age

What gray hair can have to do with infection

Everyone is different, but your hair generally tells you how old you are. When the melanocytes responsible for the production of the pigment begin to weaken, the hair first turns gray, later white.

Apart from the natural aging process, it can also happen that people suddenly turn gray. A terrible event, for example, or an illness. "Don't let your hair grow gray" is a saying that refers to it.

Researchers at the American National Institute of Health (NIH), in collaboration with the University of Alabama in Birmingham (UAB), have found an interesting genetic link between hair coloring and the immune system, specifically those immune cells that report an infection to the organism.

How defense is activated

When the body is attacked by viruses and bacteria, the immune system becomes active. In principle, all body cells have the ability to recognize attackers from outside. If this is the case, signal molecules, so-called interferons, are activated. These signal the cells to intervene and prevent viral replication. It is the effector cells of the immune system that defend the body.

The connection between the immune system booting up and hair pigmentation came as a bit of a surprise to the researchers at first. "We now have genetic tools that allow us to observe what can happen in a certain situation on a genetic level. Sometimes things happen that we didn't expect," explains Melissa Hering from the Department of Biology at UAB.

Originally, she says, they were interested in the genes that play a role in regulating stem cells. The fact that gray hair was also included in the consideration was due to the simplicity: the loss of function of the stem cells for melanocytes is relatively easy to read. If they no longer work, i.e. produce less or hardly any pigment, this can be seen quickly.

Regulation on several levels

In their study, the researchers found a connection between gray hair, the immune system and the transcription factor MITF. MITF stands for microphthalmia-associated transcription factor and is responsible for the color of the fur in vertebrates. Specifically, it has a regulating function within the melanocytes, including maintaining the interferon response. When MITF loses control of this interferon response in the stem cells of the melanocytes, the hair turns gray.

"This discovery suggests that genes that are responsible for pigmentation of hair and skin also have a control function in the immune system," says co-author William Pavan of the NIH. On the one hand, one would understand the graying process of hair, on the other hand, the connection with the immune system is important in order to better understand pigment disorders such as vitiligo (white spot disease).

Another question arises from this: To what extent is the immune system also affected if the hair turns gray prematurely? The researchers are trying to find out more about this question using the mouse model. (pok, May 3, 2018)