Novel Findings on the Role of T cells in Alopecia Areata

Aug 03, 2017

Two recent studies provide insight in the immunologic regulation of hair growth. The first study was recently published in the Cell journal and focuses on the interaction between skin T-cells and hair follicle stem cells. Stem cells are special types of cells that are very important in the process of growth, regeneration and healing for the body. Interestingly, each hair follicle is a miniature organ, in a special perpetual state of growth and renewal, and it houses stem cells crucial for both skin and hair.  Special types of skin-resident T cells, called T regulatory cell, or Tregs, are usually found around hair follicles and apparently can regulate hair growth by communicating with stem cells.  The team from University of California San Francisco led by Michael Rosenblum MD PHD, demonstrated that when the Tregs were removed from the skin, the stem cells could not regenerate hair follicles, and baldness resulted.  This finding means that in alopecia areata, different T cell types may play different roles, some implicated in the immune attack that causes hair loss, while these special Treg subtypes are actually needed for regrowth. The same team further profiled these skin-resident Tregs to show high expression of the Notch ligand family member, Jagged 1 (Jag1), and is studying whether this finding holds the key for hair growth.  

The second article by Ellebrecht et al. was suggested by one of our community members, and it actually describes a very clever way of programing immune cells to treat autoimmune diseases. This study focuses on an antibody-mediated, autoimmune, blistering skin disease called pemphigus vulgaris, which has significant morbidity and mortality. In this study, the authors worked on developing a therapy for autoimmune diseases by directly targeting and eliminating pathogenic autoimmune cells while sparing the good, protective ones. To specifically treat this disease, their concept was to use autoantigen-based immunoreceptors to direct T cells to kill autoreactive B lymphocytes. The authors engineered human T cells to express a chimeric autoantibody receptor to  eliminate disease-specific B cells. These engineered cells may provide an effective strategy for specific targeting of autoreactive B cells in antibody-mediated autoimmune disease. As we expand our knowledge of hair disease immunity, future discovery of potential antibodies to hair follicle antigens may represent a target for similarly engineered immunotherapy in antibody-mediated hair diseases.

For more information please refer to the following articles:

Ali N, Zirak B, Rodriguez RS et al. Regulatory T Cells in Skin Facilitate Epithelial Stem Cell Differentiation. Cell, 2017 Jun 1.

Ellebrecht CT, Bhoj VG, Nace A et al. Reengineering chimeric antigen receptor T cells for targeted therapy of autoimmune disease. Science, 2016 Jul 8.

Author: Dr. Natasha Atanaskova Mesinkovska, Chief Scientific Officer

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