Hair Follicle Melanocytes Initiate Autoimmunity in Alopecia Areata: a Trigger Point

Clin Rev Allergy Immunol. 2022 Dec;63(3):417-430. doi: 10.1007/s12016-022-08954-w. Epub 2022 Sep 19.

Abstract

Alopecia areata (AA) is characterized by common non-scarring alopecia due to autoimmune disorders. To date, the specific pathogenesis underlying AA remains unknown. Thus, AA treatment in the dermatological clinic is still a challenge. Numerous clinical observations and experimental studies have established that melanocytes may be the trigger point that causes hair follicles to be attacked by the immune system. A possible mechanism is that the impaired melanocytes, under oxidative stress, cannot be repaired in time and causes apoptosis. Melanocyte-associated autoantigens are released and presented, inducing CD8+ T cell attacks. Thereafter, amplification of the immune responses further spreads to the entire hair follicle (HF). The immune privilege of HF subsequently collapses, leading to AA. Herein, we present a narrative review on the roles of melanocytes in AA pathogenesis, aiming to provide a better understanding of this disease from the melanocyte's perspective.

Keywords: Alopecia areata; Autoimmunity; Hair follicle; Melanocyte; Trigger point.

Publication types

  • Review

MeSH terms

  • Alopecia Areata*
  • Autoimmune Diseases*
  • Autoimmunity
  • Hair Follicle
  • Humans
  • Melanocytes
  • Trigger Points / pathology

Supplementary concepts

  • Diffuse alopecia