’Beacon of hope’: Study finds melanocytes are target in alopecia areata

Portland, Ore. - A recent study confirms that the numbers of follicular melanocytes are significantly decreased in patients suffering from alopecia areata.

This new insight into the often severe and psychologically burdensome disease serves as a beacon of hope for patients, as researchers begin to home in on a more precise etiology that may open the door for more targeted treatments.

Past research has implicated follicular melanocytes to be the target structure in at least a proportion of patients suffering from alopecia areata.

Curtis T. Thompson, M.D., of the Oregon Health and Science University, Portland, Ore., and colleagues conducted a recent study in order to ascertain whether follicular melanocytes are a potential target in this autoimmune disease.

"I believe that the causes of the disease are more diverse than that, and different patients can potentially have different auto-antigen targets.

"It is possible, though, that a good percent of these patients do have the melanocyte as the target," Dr. Thompson says.

Study parameters

In the study, scalp samples were obtained from clinically involved scalp lesions of 18 patients with active alopecia areata and stained with MART-1 (melanoma antigen recognized by T cells).The number of melanocytes present, as well as presence or absence of dendritic processes was compared to five normal control follicles. Follicular samples were given scores from trace to 3 plus, depending on the number of melanocytes identified.

Results showed that 13 of 18 (72 percent) patients had only trace to 1 plus staining for melanocytes, usually with limited dendritic processes.

Three of 18 had 2 plus staining, and two had 3 plus staining. Melanocytes were identified in follicular epithelium at all phases of the follicular cycle, and 3 plus staining was present in all five control specimens.

Autoimmune target

"The precise etiology of alopecia areata remains unknown; however, the results of our study add further evidence that the melanocytes are the target in this disease.

"This does not prove that the melanocyte is the sole target antigen, but it appears to be at least one of the targets," Dr. Thompson says.

Alopecia areata seems to target pigmented hairs more than lighter or graying hairs.

Furthermore, non-pigmented hairs tend to re-grow first in areas of alopecia. This has led to investigations concentrating on melanocytes and melanocytic proteins as potential autoantigens.

According to Dr. Thompson, this observation - along with the fact that there is a loose association between alopecia areata and vitiligo - seems to point to at least one common denominator: Melanocytes seem to be targeted.

"I think it is fair to say that the melanocytes are the autoimmune target in vitiligo, and we do know that some of those patients also have alopecia areata.

"I believe that this association is more than a coincidence and fortifies the notion that the melanocytes are targeted," Dr. Thompson says.

Biology

According to Dr. Thompson, the biology of the melanocytes within the hair follicle is not very well defined, which is a limitation in melanocyte studies.

Whether the significant decrease seen in the number of melanocytes is because they are killed by the autoimmune attack or because the hair follicles with active alopecia areata are cycling so fast that the melanocytes do not have the time to get re-established within the follicle still remains to be seen, and is one of the questions to be answered in future research projects.

’Compelling evidence’

"This study provides enough compelling evidence to begin with much larger melanocyte studies for alopecia areata. There is a huge potential to control the disease with molecular treatment if we know what the target is.

"The disease could be treated with a molecular engineered topical therapy, circumventing the need for approval of a systemic drug which would take many years. We could provide great relief for this psychologically debilitating disease," Dr. Thompson says. DT

Disclosure: Dr. Thompson reports no relevant financial interests.