Therapy for alopecia areata in mice using parathyroid hormone agonists and antagonists, linked to a collagen-binding domain.

Alopecia areata is a common form of hair loss in which autoimmune-mediated destruction of hair follicles causes patchy hair loss, for which there is no adequate therapy. Parathyroid hormone (PTH) induces the hair cycle and promotes hair growth. PTH-CBD is a fusion protein of PTH and a bacterial collagen-binding domain (CBD), leading to targeted delivery to and retention in the skin collagen. We tested the effects of a single dose of PTH-CBD (low or high dose) on an animal model for alopecia areata, the C3H/HeJ engrafted mouse. In all the treated animals, there was a rapid (1-4 days) increase in hair growth, with sustained effects observed over a 2-month period (7/10 total treated mice<40% hair loss based on gray scale analysis, vs. 2/5 in vehicle control animals). Histological examination revealed massive stimulation of anagen VI hair follicles in treated animals despite an ongoing immune response. PTH-CBD thus shows promise as a therapy for alopecia areata, likely in conjunction with a mild immune suppressant, such as hydrocortisone cream.