According to Salk scientists, there is a surprising link between hair growth and the immune system.
More precisely, the experts discovered a rather unexpected molecular target of an alopecia treatment.
As you may or may not know, alopecia is a condition that involves hair loss due to the fact that the patient’s own immune system attacks their hair follicles.
The findings were shared in Nature Immunology earlier this week.
The research details how regulatory T cells interact with skin cells by using a hormone as a messenger as to generate new hair follicles and therefore encourage hair growth.
Associate professor at Salk’s NOMIS Center for Immunobiology and Microbial Pathogenesis and the study’s author, Ye Zheng, explains that “For the longest time, regulatory T cells have been studied for how they decrease excessive immune reactions in autoimmune diseases. Now we have identified the upstream hormonal signal and the downstream growth factor that promote hair growth and regeneration entirely separate from suppressing immune response.”
The team of researchers did not begin by studying hair loss.
Instead, they focused on the roles regulatory T cells and glucocorticoid hormones play in autoimmune diseases such as Crohn’s disease, multiple sclerosis and asthma.
They learned that the aforementioned cells did not, in fact, play an important role in any such conditions.
That’s when they redirected their focus to environments where regulatory T cells showed really high levels of glucocorticoid receptors like in the skin tissue!
They induced hair loss in mice lacking glucocorticoid receptors but also in a control group of rodents.
First author Zhi Liu, shares that “After 2 weeks, we saw a difference between the mice—the normal ones grew back their hair, but the mice without glucocorticoid receptors barely could. It was striking, and it showed us the right direction to move forward.”
The conclusion seems to be that there is communication between regulatory T cells and hair follicle stem cells in order to allow for hair regeneration.
However, TGF-beta3 are not usually produced by regulatory T cells as it happened here so the scientists scanned their databases, finding out that this happens in injured heart and muscle tissue, which is similar to how in this study, hair removal was able to simulate a skin injury.
Zheng explained that “In acute cases of alopecia, immune cells attack the skin tissue and cause hair loss. The usual remedy is using glucocorticoids to inhibit the immune reaction in the skin, so they do not keep attacking the hair follicles.”