A new study suggests that inhibiting specific enzymes within hair follicles which are in a dormant state, stimulates the hair follicles into a growth cycle. Two potential pharmacologic treatments are under trial and may have the potential to treat different hair conditions.
The study by Christiano and colleagues from the Columbia University medical centre, focused on the condition alopecia areata, also known as spot baldness. The condition is an auto immune condition where hair is absent from certain areas, particularly the scalp. Alopecia areata also frequently occurs in association with other auto immune conditions including diabetes and down syndrome. The condition may occur in individuals of all ages however most frequently in those between the ages of 30 to 60 years. Each unique hair follicle may possess its own immune and hormonal environment and this may have the effect of suppressing the immune system. When this immunosuppressive response switches off it may lead to an autoimmune reaction to the hair follicle auto antigens which may lead to alopecia areata. The team found in hair follicles after an autoimmune response, specific enzymes may impede the hair follicle from regenerating into new growth. The hair follicle is in a resting state during alopecia areata and the enzyme maintains this state.
The enzyme is called Janus kinase (JAK) and a topical treatment that inhibits this enzyme may be applied to specific areas of the skin and may stimulate hair regrowth. The treatment inhibits the JAK enzyme from keeping the hair follicle in a resting state and also prevents the auto immune response. This has opened the possibility that a pharmacological treatment involving JAK inhibitors may help alleviate other forms of baldness by stimulating hair follicles into the growth phase. The team found when looking at hair follicles of mice, the JAK inhibitors quickly stimulated the follicle out of the resting state into the growth phase. Mice treated with topical JAK inhibitors grew new hair within 10 days whereas untreated mice hair follicles stayed in the resting phase. “There are very few compounds capable of pushing hair follicles into their growth cycle so quickly,” said Angela Christiano. “Some topical agents induce tufts of hair here and there after a few weeks however very few have such a potent and rapid-acting effect.” “What may have been discovered is promising, though as of today the team is yet to show it is effective for male pattern baldness,” said Angela Christiano. “More work needs to be done to test formulations of JAK inhibitors specially made for the scalp to determine whether they may induce hair growth in humans.”
The team went on to evaluate whether T-cells were the factor leading to hair regrowth. The findings showed mice deficient in differing types of T-cells in comparison to healthy mice, had a similar capacity to enter the hair growth cycle in their response to pharmacologic treatment. The results propose the hair growth inducing effects of JAK inhibition may be a hair specific characteristic and are independent of lymphocytes. The nature of human hair cycling is hair follicles grow asynchronously and 90% are in the growth phase of the cycle at any one time. This means that in comparison to mice it may be more challenging to study human hair because the transition between the growth phase and resting phase is very short. However, with this new knowledge insight into new ways of assessing human hair may now be more efficient in the future.
The major finding was JAK inhibitors produces hair growth by the activation and generation of stem cells and these stimulate the ability of a cell to re-enter these cycles from a dormant state. The role of JAK-STAT signalling may demonstrate a general mechanism in all human stem cells. The team also found beneficial changes to the expression of certain genes in humans which are believed to be regulators of hair growth, in response to the treatments. The JAK inhibitor treatments are currently undergoing trial and a valuable result is expected.
What further development of treatments for hair conditions may be discovered next?