The skin as an endocrine organ

Abstract

Through the definition of novel biological activities of hormones and their diversity on different skin cell types, it has become apparent that the skin itself possesses the capacity to generate several hormones and substances with hormone-like activity. These substances appear to act through paracrine, autocrine, intracrine and endocrine mechanisms to fulfill their pleiotropic effects. Also new is the knowledge that the skin can metabolize hormones and produce derivatives with potentially systemic activity. These findings point towards novel concepts in our understanding of the role of skin and of its hormones as important players in homeostasis and disorders of the entire human organism. Finally, the scientists active in the field of dermato-endocrinology expect that their activities will exploit the pharmacological and therapeutic function of hormone mediators, their receptors and antagonists. The latter idea has already been realized for corticosteroids, androgens, estrogens, topical vitamin D analogues and retinoids which have today an established place in clinical dermatology.

Glucocorticoid receptors, epidermal homeostasis and hair follicle differentiation

“…3 It was also shown that the skin is also able to synthesize cholesterol, the precursor of steroid hormones, as well as different components along the GC synthetic pathway such as CRH and ACTH. 29,30 The observation that HFs can synthesize and secrete cortisol and modulate the production of other hormones by feedback mechanisms demonstrated that the skin itself acts as a peripheral endocrine organ. 31 Very recently, it was reported that epidermal keratinocytes can synthesize de novo cortisol, both in vitro and in vivo, as well as the enzymes steroid 11b-hydroxylase (CYP11B1) and 11β-hydroxysteroid dehydrogenase 2 (11βHSD2).…”

“…32 These enzymes catalyze the interconversion of active cortisol and inactive cortisone in humans (corticosterone and dehydrocorticosterone in rodents), thus controlling the biological availability of active hormone. 29,30 A main consequence of these findings is that GC action can be locally modified at the pre-receptor level through changes in the expression of these enzymes. Additionally, cortisol production as well as that of Jagged and AP2-γ, two genes that promote early keratinocyte differentiation.…”

Microbial endocrinology: host–bacteria communication within the gut microbiome

“…Although the environmental conditions to which skin is exposed can vary considerably, the composition of the skin microbiomes tends to be relatively stable (Nakatsuji et al 2013), which suggests that the skin through some mechanism actively regulates the microflora that populate it. The human skin is also an important endocrinological organ and produces a variety of systemically acting hormones (Zouboulis 2004(Zouboulis , 2009). Cells of the skin also express an array of receptors for a variety of hormones and neurotransmitters (Zouboulis 2009) including the catecholamines.…”

“…The human skin is also an important endocrinological organ and produces a variety of systemically acting hormones (Zouboulis 2004(Zouboulis , 2009). Cells of the skin also express an array of receptors for a variety of hormones and neurotransmitters (Zouboulis 2009) including the catecholamines. Stress has been known for some time to exacerbate certain skin conditions.…”

“…P. acnes, while part of the normal skin microflora, is thought to be a causative agent of acne, though its exact role is unclear (Zouboulis & Böhm 2004). P. acnes utilises sebum as a nutrient source, and sebaceous oil gland cells express receptors for catecholamines (Zouboulis 2009), so stress hormone-induced elevations in sebum levels could increase bacterial numbers and explain the worsening of acne symptoms in stressed acne patients (Zoubouilis & Böhm 2004). Metagenomic profiling of acne lesions shows that several bacterial species are also present along with P. acne, with S. epidermidis being one of the most prevalent bacterial species (Kong 2011).…”