Researchers at Harvard University have discovered that when hair follicles die due to severe stress, the body’s immune system prepares to attack more of these follicles during future similar events.
Scientists have long known that impacts our health, particularly the functioning of the immune system. However, the exact mechanisms by which stress can damage various tissues have remained poorly understood. For instance, it was unclear whether an acute stress episode could leave long-term effects.
Some previous studies hinted that stress not only affects hair follicles immediately but can also have long-lasting impacts.
Tested on Mice
Now, scientists have proven that stress can trigger and rapidly activate certain immune system cells, leading to a recurrence of hair loss in the future.
By involving laboratory mice in their research, scientists found that acute stress hyperactivates the sympathetic nervous system of the rodents, which is responsible for increased heart rate and muscle strength in the “fight or flight” response. This, in turn, activates CD8+ T cells of the mice’s immune system, which can attack hair follicles, as reported by Independent.
CD8+ T cells, or CD8+ T lymphocytes, also known as cytotoxic T killers, play a crucial role in cellular immunity by recognizing and destroying virus-infected cells.
Researchers assert that even after the initial stress subsides, these CD8+ T cells can provoke renewed hair loss during subsequent inflammation.
“Our results showed that a single episode of acute stress causes immediate damage and thereby activates and increases the number of rare autoreactive CD8+ T cells, preparing the tissue for future immune attacks,” the team wrote in the journal Cell.
Thus, a single episode of acute stress can create a predisposition in that same tissue for future damage, the scientists say. They suggested that this type of immune response might be a way for the body to sacrifice metabolically costly cells that can, however, regenerate to preserve essential stem cells.
According to the researchers, by sacrificing some hair follicles in the face of danger, the body can conserve stem cells that regenerate tissues after the threat has passed. This could be a “strategic compromise aimed at preserving limited resources for critical stress responses.”
“These mechanisms help explain the onset of alopecia areata and its frequent association with stress,” the scientists noted.
The team plans to conduct further research on stress-induced hair loss involving human participants. They hope this will help them better understand the causes of diseases such as multiple sclerosis, , and lupus.
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