160 Inhibition of Ornithine Decarboxylase: Effects on the Hair Follicle Cytoskeleton and Epidermis of Patients with Pseudofolliculitis Barbae (PFB)

M. Ericson, C. Boeck and M. Hordinsky Dept. of Dermatology, University of Minnesota Academic Health Center, Minneapolis, Minnesota, USA

The purpose of this study was to obtain information on the mechanism of action of eflornithine hydrochloride cream 13.9%, an irreversible inhibitor of the enzyme ornithine decarboxylase, in the treatment of Grade 3 PFB in adult males of African-American descent. We hypothesized b.i.d. application of the cream for 16 weeks to the beard region of 10 men with PFB would alter epidermal thickness, the hair fiber, and hair follicle structure through disruption of actin bundles. Photographs and 4-mm skin biopsies were obtained from PFB lesions at Treatment Days 2 and 114. At the end of the treatment course, clinical severity of PFB improved in the majority of patients. Formalinfixed biopsy samples were stained with hematoxylin and eosin and Ki67 antibody, a marker for cell proliferation. Zamboni’s-fixed biopsy samples were processed and stained for laser scanning confocal microscopic (LSCM) analysis. In post-treatment samples; (1) the number of miniaturized follicles increased and the number of large curved follicles decreased, (2) epidermal thickness remained the same in all samples, (3) epidermal differentiation appeared more organized, and (4) Ki-67 staining revealed a decrease in epidermal staining in all but 2 patients. LSCM analysis revealed changes in actin filament architecture in the keratogenous zone of the outer root sheath of anagen beard hair follicles. Actin filament bundles also appeared very disorganized and parallel orientation was lost. We conclude that eflornithine hydrochloride cream 13.9% may be an effective drug in the management of PFB and possibly other skin diseases characterized by abnormal cell proliferation. Our data also suggest that eflornithine hydrochloride cream 13.9% disrupts the actin cytoskeleton of the actively growing beard hair follicle. Disruption of this scaffolding could lead to subsequent loss of follicle integrity and alteration of growth characteristics of the beard hair follicle.