Aging in the sebaceous gland

Abstract

Sebaceous glands (SGs) originate from hair follicular stem cells and secrete lipids to lubricate the skin. The coordinated effects of intrinsic and extrinsic aging factors generate degradation of SGs at a late age. Senescence of SGs could be a mirror of the late aging of both the human body and skin. The procedure of SG aging goes over an initial SG hyperplasia at light-exposed skin areas to end with SG atrophy, decreased sebum secretion, and altered sebum composition, which is related to skin dryness, lack of brightness, xerosis, roughness, desquamation, and pruritus. During differentiation and aging of SGs, many signaling pathways, such as Wnt/β-catenin, c-Myc, aryl hydrocarbon receptor (AhR), and p53 pathways, are involved. Random processes lead to random cell and DNA damage due to the production of free radicals during the lifespan and neuroendocrine system alterations. Extrinsic factors include sunlight exposure (photoaging), environmental pollution, and cigarette smoking, which can directly activate signaling pathways, such as Wnt/β-catenin, Notch, AhR, and p53 pathways, and are probably associated with the de-differentiation and hyperplasia of SGs, or indirectly activate the abovementioned signaling pathways by elevating the inflammation level. The production of ROS during intrinsic SG aging is less, the signaling pathways are activated slowly and mildly, and sebocytes are still differentiated, yet terminal differentiation is not completed. With extrinsic factors, relevant signaling pathways are activated rapidly and fiercely, thus inhibiting the differentiation of progenitor sebocytes and even inducing the differentiation of progenitor sebocytes into keratinocytes. The management of SG aging is also mentioned.

Biomarkers of aging

“…Hair graying is caused by loss of HF melanocytes and their stem cells (Arck et al, 2006;Nishimura et al, 2005), and is also associated with depletion of hair progenitors in human scalp HFs (Wu et al, 2022a). HF aging is also accompanied by changes in the distribution of nearby sensory neurons and atrophy or dysfunction of SGs (Giangreco et al, 2008;Hou et al, 2022).…”

‘Speed‐ageing’ of human skin in serum‐free organ culture ex vivo: An instructive novel assay for preclinical human skin ageing research demonstrates senolytic effects of caffeine and 2,5‐dimethylpyrazine

“…We have recently shown in human hair follicle organ culture that a natural pheromone and food ingredient, DMP, 56 promotes hair matrix cell proliferation and hair growth ex vivo, at least in part, via stimulating TRPM5 30 . Since pheromone‐induced TRPM5‐coupled signalling, which resulted in growth promotion, also modified the intrafollicular expression of several factors that also impact on ageing/senescence (such as fibroblast growth factor 7, 57 insulin‐like growth factor 1, 58 transforming growth factor β1/2 59 and Wnt signalling 60 ), 30 we hypothesized that DMP might also retard the accelerated skin ageing phenotype. Simultaneously, we wished to probe whether our hSOC system can be used to test the anti‐ageing efficacy of topically applied cosmetic candidate senolytics.…”

Differential diagnosis and variants of acne vulgaris

“…Sebaceous hyperplasia is a benign disorder not requiring treatment, although cosmetic therapies include cryosurgery, photodynamic therapy, laser treatment, electrodesiccation, excision, or isotretinoin. 8 If there is a solitary lesion located on the sun-exposed skin that is pink, painful, bleeding, or is occurring in a high-risk population, then a dermatology referral is recommended to rule out basal cell carcinoma as they can be clinically similar.…”