New cause of baldness found, may lead to hair loss treatment

Scientists have accidentally discovered a new cause of baldness that may help develop treatments for hair loss.
Researchers at University of California, San Francisco in the US found that regulatory T cells (Tregs), a type of immune cell generally associated with controlling inflammation, directly trigger stem cells in the skin to promote healthy hair growth.
Without these immune cells as partners, the researchers found, the stem cells cannot regenerate hair follicles, leading to baldness.
"Our hair follicles are constantly recycling: when a hair falls out, the whole hair follicle has to grow back," said Michael Rosenblum, an assistant professor at UCSF.

"This has been thought to be an entirely stem cell- dependent process, but it turns out Tregs are essential. If you knock out this one immune cell type, hair just does not grow," said Rosenblum, senior author on the research paper published in the journal Cell.
The new study suggests that defects in Tregs could be responsible for alopecia areata, a common autoimmune disorder that causes hair loss, and could potentially play a role in other forms of baldness, including male pattern baldness, Rosenblum said.

Since the same stem cells are responsible for helping heal the skin after injury, the study raises the possibility that Tregs may play a key role in wound repair as well.

Rosenblum said the findings may have implications for alopecia areata, an autoimmune disease that interferes with hair follicle regeneration and causes patients to lose hair in patches from their scalp, eyebrows, and faces.
Alopecia is among the most common human autoimmune diseases - it is as common as rheumatoid arthritis, and more common than type 1 diabetes - but scientists have little idea what causes it.