Chitinase 3-Like 1 and C-X-C Motif Chemokine Ligand 5 Proteins and the Hair Cycle

The study explores the role of dermal papilla cells (DPCs) in hair growth, focusing on their recovery after stress treatments. It highlights the importance of proteins Chitinase 3-like 1 (CHI3L1) and C-X-C motif chemokine 5 (CXCL5) in promoting the proliferation of outer root sheath cells (ORSCs), essential for hair follicle growth. In a mouse model, these proteins increased secretion after the anagen phase transition, suggesting their role in activating hair growth. In hair-loss models treated with testosterone or 17β-estradiol, lower levels of these proteins were found in the telogen phase, indicating their potential significance in regulating hair growth.