Scientists from Salk found an unexpected molecular target of a common treatment for alopecia, a condition in which a person’s immune system attacks their own hair follicles, causing hair loss.
The findings describe how immune cells called regulatory T cells interact with skin cells using a hormone as a messenger to generate new hair follicles and hair growth.
The research is published in Nature Immunology and was conducted by Ye Zheng et al.
For the longest time, regulatory T cells have been studied for how they decrease excessive immune reactions in autoimmune diseases.
In the study, the team identified the upstream hormonal signal and downstream growth factor that actually promote hair growth and regeneration completely separate from suppressing the immune response.”
In the study, the team examined hair loss in normal mice and mice lacking glucocorticoid receptors in their regulatory T cells.
They found that glucocorticoids and regulatory T cells did not function together to play a big role in any of these conditions.
They saw a noticeable difference between the mice—the normal mice grew back their hair, but the mice without glucocorticoid receptors barely could.
The findings suggested that some sort of communication must be occurring between regulatory T cells and hair follicle stem cells to allow for hair regeneration.
Using a variety of techniques for monitoring multicellular communication, the scientists then investigated how the regulatory T cells and glucocorticoid receptors behaved in skin tissue samples.
They found that glucocorticoids instruct the regulatory T cells to activate hair follicle stem cells, which leads to hair growth.
This crosstalk between the T cells and the stem cells depends on a mechanism whereby glucocorticoid receptors induce the production of the protein TGF-beta3, all within the regulatory T cells.
TGF-beta3 then activates the hair follicle stem cells to differentiate into new hair follicles, promoting hair growth.
The additional analysis confirmed that this pathway was completely independent of regulatory T cells’ ability to maintain immune balance.
The team says in acute cases of alopecia, immune cells attack the skin tissue, causing hair loss. The usual remedy is to use glucocorticoids to inhibit the immune reaction in the skin, so they don’t keep attacking the hair follicles.
Applying glucocorticoids has the double benefit of triggering the regulatory T cells in the skin to produce TGF-beta3, stimulating the activation of the hair follicle stem cells.
This study revealed that regulatory T cells and glucocorticoid hormones are not just immunosuppressants but also have a regenerative function.
If you care about hair loss, please read studies about new method to prevent hair loss, and new way to treat hair loss.
For more information about hair loss, please see recent studies about a new cause of hair loss, and results showing that scientists find new way to treat hair loss and skin aging.
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