Kevin J. McElwee

Alopecia areata: an autoimmune disease?

Abstract: A wide range of hypotheses such as focal infection, trophoneur‐ oses, and endocrine dysfunction, have been previously proposed to explain the pathogenesis of alopecia areata (AA). Currently, the most widely held belief is that AA is an autoimmune disease with cellular and/or humoral immunity directed against anagen hair follicle antigen(s). However, until recently evidence in support of an autoimmune mechanism of AA has been largely circumstantial. More fundamental evidence has recently been amassed in support of AA as an autoimmune disease by using animal models. These data include: 1) identification of cross‐species hair follicle specific IgG autoantibodies, 2) The ability to induce AA in an animal model with transfer of skin from affected to naive individuals, and 3) the induction of disease by transfer of lymphocytes to human skin grafted to severe combined immunodeficiency mutant mice. A review of the pre‐ vious and current data related to the autoimmune basis of AA is provided to put into perspective the future studies needed to definitively determine whether AA is an autoimmune disease.

Topical FK506 : A potent immunotherapy for alopecia areata? Studies using the dundee experimental bald rat model

We elected to examine the efficacy of the topically applied immunosuppressive agent FK506 (Prograf®) in the treatment of alopecia areata (AA) using the Dundee experimental bald rat (DEBR) model. Thirty lesional DEBR rats were allocated to five groups of six. Group I rats received 0.1 mL of a 0.25% solution of FK506 within a 2x2 cm marked area on one bald flank twice a week (125μg FK506/cm2 per week) for 8 weeks, while the contralateral flank was left untreated. In group II, 0.05mL of a 0.1% solution of FK506 was applied 5 days per week on one flank (62.5 μg FK506/cm2 per week) and control vehicle to the opposite flank for 8 weeks. Group III rats were treated as in group II except that drug and vehicle were applied twice a week (25 μg FK506/cm2 per week) for 4 weeks. A positive control group received orally administered cyclosporin A (CsA) (10mg/kg daily) for 8 weeks and a further group was left untreated. Rats were regularly examined and photographed with skin biopsies taken from groups II and III. All FK506‐treated rats regrew hair at the site of drug application within 14–21 days. Growth continued for 3 weeks beyond termination of treatment after which gradual hair loss was observed. No hair growth was seen as a result of vehicle application and hair loss continued on untreated areas and in the untreated control group. Immunohistology revealed a drastic reduction in the follicular inflammatory infiltrate at the site of the FK506 application. The oral CsA group responded by simultaneous regrowth of hair over the whole body. Our findings suggest that FK506 may have considerable potential as a topical treatment for AA.

The DEBR rat, alopecia areata and autoantibodies to the hair follicle

Summary Many attempts have been made to implicate hair follicle‐specific autoantibodies in the pathogenesis of alopecia areata (AA), a suspected autoimmune disease. Using the DEBR rat model for AA, we developed a refined indirect immunofluorescent technique to examine the sera from individual rats for the presence of autoantibodies to the hair follicle and to other tissues. Sera were tested on cryostat sections from normal PVG/Ola rats and DEBR rats.

Dietary soy oil content and soy‐derived phytoestrogen genistein increase resistance to alopecia areata onset in C3H/HeJ mice

Abstract: Alopecia areata (AA) is a complex, multi‐factorial disease where genes and the environment may affect susceptibility and severity. Diet is an environmental factor with the potential to influence disease susceptibility. We considered dietary soy (soya) oil content and the soy‐derived phytoestrogen genistein as potential modifying agents for C3H/HeJ mouse AA. Normal haired C3H/HeJ mice were grafted with skin from spontaneous AA affected mice, a method previously shown to induce AA. Grafted mice were given one of three diets containing 1%, 5% or 20% soy oil and observed for AA development. In a separate study, mice on a 1% soy oil diet were injected with 1u2003mg of genistein three times per week for 10u2003weeks or received the vehicle as a control. Of mice on 1%, 5%, and 20% soy oil diets, 43 of 50 mice (86%), 11 of 28 mice (39%), and 2 of 11 mice (18%) developed AA, respectively. Four of 10 mice injected with genistein and 9 of 10 controls developed AA. Mice with AA had hair follicle inflammation consistent with observations for spontaneous mouse AA, but no significant association was observed between the extent of hair loss and diet or genistein injection. Mice that failed to develop AA typically regrew white hair from their skin grafts associated with a moderate macrophage and dendritic cell infiltration. Soy oil and derivatives have previously been reported to modify inflammatory conditions. Hypothetically, soy oil compounds may act on C3H/HeJ mice through modulating estrogen‐dependent mechanisms and/or inflammatory activity to modify AA susceptibility.

Alopecia Areata in C3H/HeJ Mice Involves Leukocyte-mediated Root Sheath Disruption in Advance of Overt Hair Loss

Alopecia areata (AA) can be induced in C3H/HeJ mice by grafting full-thickness AA-affected skin. An 8- to 12-week delay between surgery and overt hair loss onset provides an opportunity to examine disease pathogenesis. Normal haired C3H/HeJ mice were sham-grafted or grafted with AA-affected skin. Mice were euthanatized 2, 4, 6, 8, 10, and 12 weeks after surgery along with chronic AA-affected mice as a positive control. Until 6 weeks after grafting, inflammation was only evident around anagen-stage hair follicles in host skin adjacent to but not distant from the AA-affected graft. From 8 weeks on, AA-grafted but not sham-grafted mice exhibited a diffuse dermal inflammation at distant sites that progressively focused on anagen-stage hair follicles at 10 and 12 weeks. Perifollicular inflammation was primarily composed of CD4+ and CD8+ cells associated with follicular epithelium intercellular adhesion molecule -1 expression. Only CD8+ cells penetrated intrafollicularly by 12 weeks after surgery, although both CD4+ and CD8+ intrafollicular cells were observed in chronic AA-affected mice. Under electron microscopy, intrafollicular lymphocyte and macrophage infiltration associated with hair follicle dystrophy was prominent 10 weeks after surgery, primarily within the differentiating outer and inner root sheaths. This study shows that focal follicular inflammation develops some time in advance of overt hair loss and focuses on the differentiating root sheaths in C3H/HeJ mice. The severity of inflammation and the degree of hair follicle dystrophy induced by the infiltrate appear to reach a threshold level before overt hair loss occurs.

Melanocyte and gonad activity as potential severity modifying factors in C3H/HeJ mouse alopecia areata

Abstract: Circumstantial evidence has previously suggested gonad derived steroid hormones and melanogenesis related antigens may modify human alopecia areata (AA). AA‐like hair loss can be induced in C3H/HeJ mice after skin allografts from spontaneous AA‐affected mice. This inducible model was used to evaluate hormones and hair follicle melanocyte presence as disease‐severity modifiers. Ten females and 9 males were gonadectomized and received AA‐affected allografts. All gonadectomized mice had 2–4 weeks delay in AA onset relative to non‐gonadectomized controls. Two females and 4 males failed to develop any AA by 25 weeks after grafting. The experiment was repeated with gonadectomized female and male mice plus non‐gonadectomized mice subcutaneously implanted with silastic capsules containing 80 μg 17β estradiol or 10 mg 5α dihydrotestosterone, respectively. Five of 11 ovariectomized and 9 of 11 non‐ovariectomized, estradiol supplemented females developed AA with extremely rapid progression. Three of 8 castrated, but none of 11 non‐castrated, dihydrotestosterone‐supplemented males expressed AA. In a separate study, 14 mice were freeze‐branded, producing white hair on the dorsal lumbar region, and later received full‐thickness allografts. Thirteen mice developed patchy pigmented and non‐pigmented hair loss. One mouse developed diffuse, pigmented hair loss, but with white hair survival persisting 25 weeks after grafting. The results suggest that gonadal steroid hormones can modulate C3H/HeJ mouse AA where estradiol promoted rapid progression of AA while dihydrotestosterone increased resistance to AA onset. In general, both pigmented and non‐pigmented C3H/HeJ mouse hair is susceptible to AA. Murine AA susceptibility and severity clearly involves an interplay between genetic and epigenetic factors.