Cutaneous sebum and follicular lipids

Cutaneous sebum and follicular lipids, commonly known as sebum, are a complex mixture of lipids (glycerides 30-50%, fatty acids 15-30%, wax esters 26-30%, squalene 12-20%, cholesterol 1.5-2.5%) produced by sebaceous glands in the pilosebaceous unit through holocrine secretion of maturing sebocytes. These lipids coat the skin and hair, forming a hydrolipidic film that prevents dehydration, maintains suppleness, and creates an acidic mantle (pH 4.5-6.0) for antimicrobial defense while delivering antioxidants like vitamin E and providing photoprotection. Regulated by androgens (e.g., DHT via 5-alpha reductase), growth factors (insulin, IGF), PPARs, and other signals, sebum composition varies with differentiation markers like FADS2 in sebocytes. In diseases like acne, excess sebum with altered lipids (e.g., oxidized squalene, reduced vitamin E) promotes inflammation, hyperkeratinization, and *P. acnes* overgrowth, while reduced sebum links to atopic dermatitis barrier defects. Though not a discrete molecular target like a receptor or enzyme, sebum lipids modulate immunity (e.g., macrophage phagocytosis, keratinocyte TSLP) and dermis homeostasis, with research exploring indirect modulation via hormones or diet for skin disorders, but no direct drugs target the lipids themselves.

Other names

SebumSebaceous lipidsSkin surface lipids (partial overlap with epidermal lipids)