Researchers at the Salk Institute (USA) have been surprised by the results of a study they have carried out, and that is that they have found a molecular target for a drug to treat alopecia, an immune system problem in which the body begins to self-destruct its own hair follicles.
Specifically, the results, which have been published in the journal Nature Immunology, have described how regulatory T cells – immune cells – are related to skin cells. To do this, they use a hormone as a messenger, the glucocorticoid hormone, which manages to promote the creation of new hair follicles, which leads to hair growth.
“Regulatory T cells have long been studied for how they decrease excessive immune reactions in autoimmune diseases. We have now identified the upstream hormonal signal and downstream growth factor that actually promote hair growth and regrowth completely independent of suppression of the immune response,” said Ye Zhengg, lead author of the study.
Glucocorticoids are able to instruct regulatory T cells to activate hair follicle stem cells and hair to grow
The most curious thing about the research is that the authors did not intend to study hair loss, but rather wanted to know what the functions of regulatory T cells and glucocorticoid hormones were -steroid hormones derived from cholesterol generated by the adrenal gland and other tissues – in autoimmune diseases. To do this, they tested these immune components against Crohn’s disease, multiple sclerosis and asthma.
However, they found that they did not play a major role in these conditions, and turned the tide toward environments in which regulatory T cells express high levels of glucocorticoid receptors, for example, in the skin. To test this, they tested healthy mice and mice that lacked glucocorticoid receptors on their regulatory T cells, all of which caused hair loss.
Immunosuppressive and regenerative cells
The researchers found that after two weeks the normal mice grew their hair back, while those without glucocorticoid receptors barely grew at all. This finding indicated that there could be some type of communication between the regulatory T cells and the stem cells of the hair follicle, which made hair regeneration possible.
Using various techniques to monitor multicellular communication, the researchers investigated how regulatory T cells and glucocorticoid receptors behaved in skin tissue samples. They found that glucocorticoids are able to instruct regulatory T cells to activate stem cells present in the hair follicle, causing hair to grow.
This interference between T cells and stem cells depends on a mechanism by which glucocorticoid receptors generate the production of the protein TGF-beta3, all within regulatory T cells. TGF-beta3 then triggers hair follicle stem cells to differentiate into new hair follicles, promoting hair growth.
They discovered that regulatory T cells and glucocorticoid hormones are not only immunosuppressive, but also regenerative
Further analysis confirmed that this pathway was completely independent of the ability of regulatory T cells to maintain immune balance. However, regulatory T cells do not normally generate TGF-beta3, but in the study they did. In the analysis of the databases, the scientists found that this fact occurs in the muscular and cardiac tissue that is injured.
“In acute cases of alopecia, immune cells attack skin tissue causing hair loss. The usual remedy is to use glucocorticoids to suppress the immune reaction in the skin, so they don’t continue to attack the hair follicles. Applying glucocorticoids has the dual benefit of activating regulatory T cells in the skin to produce TGF-beta3, stimulating the activation of hair follicle stem cells,” explains Zheng.
Finally, the scientists’ latest finding revealed that regulatory T cells and glucocorticoid hormones are not only immunosuppressive, but also have a regenerative function.
.
