Neurotrophology of the Hair Follicle: Neurotrophins Act as Auto- and Paracrine Growth Factors and Immunomodulators

The document discussed the role of neurotrophins, particularly nerve growth factor (NGF), as growth factors and immune modulators in hair follicles. It highlighted that NGF, produced by hair follicles, regulated their growth and response to stress. In mouse skin, changes in NGF expression affected nerve fiber density and neuro-immune interactions. In human hair follicles, NGF signaling inhibited hair growth by inducing apoptosis-driven regression, a process dependent on the p75 receptor. This regression could be triggered by stress mediators like substance P, leading to neurogenic inflammation and collapse of hair follicle immune privilege. The study underscored the importance of neurotrophins in both mouse and human hair follicle biology and their potential as models for studying epithelial growth and neuro-immune interactions.