P5.54 Human vellus and terminal hair follicles both express components of the POMC system

K Stieler¹, A Vogt¹, Z Li², M Böhm², U Blume-Peytavi¹

¹Department of Dermatology, Center of Experimental and Applied Cutaneous Physiology, Charité - University Medicine Berlin ²Department of Dermatology, University Münster, Germany

Proopiomelanocortin (POMC) peptides such as ACTH play an important role in pigmentation of human skin and hair. Both peptides bind to a family of transmembrane receptors known as the melanocortin receptors (MC-Rs). To investigate the in vivo and in vitro expression of ACTH and MC-Rs we performed immunohistochemical studies on human terminal and vellus hair follicles, whole organ cultures (WOC), vellus hair keratinozytes (VHK) and terminal hair keratinozytes (THK). In vivo immunoreactivity for ACTH, MC-1R and MC-4R was detected in both human terminal and vellus hair follicles, with a pronounced increase of staining intensity in the suprabulbar and bulbar region of anagen hair follicles. There was no detectable difference in the staining pattern of strong, pigmented terminal hair follicles as compared to fine, silky and non-pigmented vellus hair follicles. The in vitro immunohistochemical staining revealed positivity for all cultures with different intensities for VHK and THK and a stronger expression of MC-4R in WOC differentiating cortex cells. These results indicate that POMC-derived peptides may play a regulatory role in the human hair follicle independent of the pigmentation process.