IL-15 Prolongs Anagen, Stimulates Proliferation, and Suppresses Apoptosis in the Hair Matrix of Human Scalp Hair Follicles
Takahiro Suzuki, FERNANDA DINELLI SCALA, Dana‐Lee Demetrius, Jennifer Gherardini, Jose Rodriguez-Feliz, Gorana Kuka-Epstein, Jérémy Chéret, Ralf Paus
Abstract
The hair cycle clock that controls human hair follicle (HF) cycling remains elusive (Al-Nuaimi et al., 2014; Nicu et al., 2020; Paus and Foitzik, 2004). However, it is well appreciated that the massive HF transformations from growth (anagen) to apoptosis-driven regression (catagen) and relative quiescence (telogen) back to anagen (Geyfman et al., 2015; Paus and Cotsarelis, 1999; Paus et al., 1999) are mainly driven by cyclic changes in the intrafollicular production and activity of potent hair growth–regulatory growth factors, such as insulin-like growth factor 1 (IGF-1) (Chéret et al., 2018; Philpott et al., 1994; Rudman et al., 1997), TGFβ2 (Hibino and Nishiyama, 2004; Soma et al., 2002; Tsuji et al., 2003), HGF (Nicu et al., 2021), and Wnt signals (Hawkshaw et al., 2018). However, it is much less well understood how cytokines affect human HF growth and cycling under physiological circumstances.