Immune modulation of hair follicle regeneration

Abstract

The mammalian hair follicle undergoes repeated bouts of regeneration orchestrated by a variety of hair follicle stem cells. The last decade has witnessed the emergence of the immune niche as a key regulator of stem cell behavior and hair follicle regeneration. Hair follicles chemotactically attract macrophages and T cells so that they are in range to regulate epithelial stem cell quiescence, proliferation and differentiation during physiologic and injured states. Disruption of this dynamic relationship leads to clinically significant forms of hair loss including scarring and non-scarring alopecias. In this review, we summarize key concepts behind immune-mediated hair regeneration, highlight gaps in the literature and discuss the therapeutic potential of exploiting this relationship for treating various immune-mediated alopecias.

CD36 and CD97 in Pancreatic Cancer versus Other Malignancies

“…Recently, systematic information about quiescence in different cell types has been constantly accumulating, e.g., neurons [216], hair follicle stem cells [217], muscle stem cells [217], vessels ("During quiescence, the angiogenic switch is 'off'") [218], vessels during diabetes [219], pancreatic stem cells [109], beta-cells during diabetes [220], mesenchymal stem cells [221], or pancreatic progenitor-like acinar cells [222].…”

Epidermal Stem Cells in Hair Follicle Cycling and Skin Regeneration: A View From the Perspective of Inflammation

“…Activation of the mammalian target of rapamycin complex 1 (mTORC1) was observed in the bulge and hair germ cells in a growth phase-dependent manner suggesting its role in anagen activation (Kellenberger and Tauchi, 2013). Thus, macrophages are involved in both physiological TAT, plucking-induced anagen, and WIH-A in the described experiment; therefore, the contribution ratio of skin resident macrophages and those arrived at the wound bed is unknown (Rahmani et al, 2020).…”

“…Also, it has the ability to intensify stem cell activity for production of differentiated progeny and restoration of lesions (Rahmani et al, 2020).…”

“…Immune system supports regenerative processes via direct interactions with invaders and clearance of wound debris. Also, it has the ability to intensify stem cell activity for production of differentiated progeny and restoration of lesions ( Rahmani et al, 2020 ).…”

Skin organoids: A new human model for developmental and translational research

“…Although various compartments of hair follicle maintain some degree of "immune privilege" during the growth cycle under normal circumstances, this privilege would be broken in a wound or scar setting. 62 Recent clinical trials on cell therapies for macular degeneration and Parkinson's disease show promising early results of autologous iPSC-based therapies. 63,64 However, these studies also reveal that the time required for iPSC derivation, validation and differentiation can be over a year, which limits the patient population that could benefit from these therapies.…”