Comparison of Alopecia areata in Human and Nonhuman Mammalian Species

Abstract

Alopecia areata (AA) is a nonscarring form of inflammatory hair loss in humans. AA-like hair loss has also been observed in other species. In recent years the Dundee experimental bald rat and the C3H/HeJ mouse have been put forward as models for human AA. AA in all species presents with a wide range of clinical features from focal, locally extensive, diffuse hair loss, to near universal alopecia. Histologically, all species have dystrophic anagen stage hair follicles associated with a peri- and intrafollicular inflammatory cell infiltrate. Autoantibodies directed against anagen stage hair follicle structures are a consistent finding. Observations on AA pathogenesis suggest nonhuman species can provide excellent models for the human disease. Ultimately, animal models will be used to determine the genetic basis of AA, potential endogenous and/or environmental trigger(s), mechanism(s) of disease initiation and progression, and allow rapid evaluation of new and improved disease treatments.

The role of lymphocytes in the development and treatment of alopecia areata

“…Cells disrupted by CD8 + cytotoxic cells release nucleic acids and self-antigens, these complexes can activate APCs promoting T cell priming, additional lymphocyte recruitment, and effector differentiation [31,39,59,60]. Peri-and intra-follicular inflammatory cell infiltration promotes formation of dystrophic anagen stage hair follicles in early AA and later may enforce a chronic inactive telogen state [61].…”

Epidermal Cadm1 Expression Promotes Autoimmune Alopecia via Enhanced T Cell Adhesion and Cytotoxicity

“…It is characterized by an extensive skin inflammatory T cell infiltrate, hair follicle destruction and focal, extensive, or complete baldness in males and females (1,2). Inflammation in autoimmune alopecia involves both CD4 + and CD8 + T cells and is most commonly observed in association with dystrophic anagen (growing) hair follicles (3). Alopecia also occurs in other autoimmune diseases, including lupus erythematosus, raising the possibility of common mechanisms (4,5).…”

Alopecia areata: an autoimmune disease?

“…However, the lack of success in isolating an infectious agent capable of inducing AA by inoculation was a significant stumbling block to this hypothesis (6)(7)(8). Although recent research has once again raised the possibility of an infectious agent such as cytomegalovirus inducing or activating AA (9,10), other investigators were unable to document the ability of cytomegalovirus infection to induce AA in humans and mouse models (11)(12)(13)(14).…”