Androgens, Animals, Arachidonic Acid, Cell Differentiation, Endocannabinoids, Growth Hormone, Hair Follicle, Humans, Immunity, Innate, Inflammation Mediators, Intercellular Signaling Peptides and Proteins, Lipids, Neurotransmitter Agents, Peroxisome Proliferator-Activated Receptors, Pro-Opiomelanocortin, Sebaceous Gland Diseases, Sebaceous Glands, Sebum, TRPC Cation Channels, Cannabinoid Receptor Modulators, Physiology, 0606 Physiology, 1116 Medical Physiology, 1106 Human Movement and Sports Sciences
The pilosebaceous unit of the human skin consists of the hair follicle and the sebaceous gland. Within this "mini-organ", the sebaceous gland has been neglected by the researchers of the field for several decades. Actually, it was labeled as a reminiscence of human development ("a living fossil with a past but no future"), and was thought to solely act as a producer of sebum, a lipid-enriched oily substance which protects our skin (and hence the body) against various insults. However, due to emerging research activities of the past two decades, it has now become evident that the sebaceous gland is not only a "passive" cutaneous "relic" to establish the physico-chemical barrier function of the skin against constant environmental challenges, but it rather functions as an "active" neuro-immuno-endocrine cutaneous organ. This review summarizes recent findings of sebaceous gland research by mainly focusing on newly discovered physiological functions, novel regulatory mechanisms, key events in the pathology of the gland, and future directions in both experimental and clinical dermatology.