What causes alopecia areata?

Abstract

The pathobiology of alopecia areata (AA), one of the most frequent autoimmune diseases and a major unsolved clinical problem, has intrigued dermatologists, hair biologists and immunologists for decades. Simultaneously, both affected patients and the physicians who take care of them are increasingly frustrated that there is still no fully satisfactory treatment. Much of this frustration results from the fact that the pathobiology of AA remains unclear, and no single AA pathogenesis concept can claim to be universally accepted. In fact, some investigators still harbour doubts whether this even is an autoimmune disease, and the relative importance of CD8+ T cells, CD4+ T cells and NKGD2+ NK or NKT cells and the exact role of genetic factors in AA pathogenesis remain bones of contention. Also, is AA one disease, a spectrum of distinct disease entities or only a response pattern of normal hair follicles to immunologically mediated damage? During the past decade, substantial progress has been made in basic AA-related research, in the development of new models for translationally relevant AA research and in the identification of new therapeutic agents and targets for future AA management. This calls for a re-evaluation and public debate of currently prevalent AA pathobiology concepts. The present Controversies feature takes on this challenge, hoping to attract more skin biologists, immunologists and professional autoimmunity experts to this biologically fascinating and clinically important model disease.

Study of Th1/Th2 balance in peripheral blood mononuclear cells of patients with alopecia areata

“…Multiple lines of evidence have demonstrated that immune system disturbances and breakdown of T cell tolerance are the key players in the pathogenesis and development of AA [13,14]. Moreover, it is now accepted that the imbalance of Th1/Th2 immunity becomes the cause of various immune diseases including AA [15][16][17].…”

Evaluation of thyroid function status in patients with alopecia areata

“…The first theory put forward was the viral, fungal, and bacterial infection theory, followed by the genetic theory, and finally the environmental theory. 9,10 These theories had all been adduced as triggers of AA evolution in humans by various authors. [10][11][12] However, the most accepted and plausible of these theories in AA evolution and etiopathogenesis is based on that of autoimmunity which posits that AA is an autoimmune disease directed against putative autoantigen of anagen phase hair follicles.…”

New Modalities in the Treatment of Refractory Alopecia Areata

“…It is considered to be a complex genetic, immune-mediated disease [1][2][3][4][5]. It randomized controlled studies in AA have been published [22].…”