Sebaceous Immunobiology: Skin Homeostasis, Innate Immunity Coordination, Inflammatory Response, and Disease Associations

The document reviews the multifaceted role of sebaceous glands (SG) in skin health, termed "sebaceous immunobiology," highlighting their contributions to skin homeostasis, innate immunity, and the pathophysiology of various skin diseases. It emphasizes the importance of sebaceous lipids in skin immunity, with sebocytes acting as immune regulators and expressing inflammatory mediators that influence T cell polarization. The review also discusses the gland's role in hair follicle morphogenesis and how immune cells regulate SG function. Advances in stem cell and sebocyte models have improved our understanding of SG physiology and the control mechanisms of sebocyte function. The complex regulation of sebocyte-induced immunological reactions by factors like sex steroids and endocannabinoids is linked to skin diseases such as acne, atopic dermatitis, and hair diseases. The document also explores the immunological aspects of SGs, including their role in the immune response to bacterial antigens and the production of antimicrobial peptides. It touches on the in situ production and action of sex steroids in SG physiology and pathology, the importance of transcription factors like NGFI-B and GATA6, and the role of peroxisome proliferator-activated receptor gamma (PPARγ) in SG function and as a potential therapeutic target for SG-related inflammatory skin diseases. Lastly, it describes the SG's involvement in hair follicle regulation and scarring alopecia, and its potential as a target for future therapeutic developments.