A Novel Pathway for Hormonally Active Calcitriol

Lehmann, Bodo; Knuschke, Peter; Meurer, Michael

doi:10.1159/000053278

Cited by 9 publications

(10 citation statements)

References 11 publications

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“…The skin is the unique site of cholecalciferol synthesis 152,153 which, like steroid hormones, derives from cholesterol. Epidermal keratinocytes contain both the mechanism needed to produce calcitriol and VDR 116 .…”

Section: Vitamin Dmentioning

confidence: 99%

“…In addition, they were found to slowly but constantly form calcitriol from a large reservoir of cholecalciferol. Interestingly, physiological doses of ultraviolet light B radiation at 300 nm induce the conversion of 7-dehydrocholesterol via pre-cholecalciferol and cholecalciferol into calcitriol in the pmol range in epidermal keratinocytes 153 . Skin can further degrade cholecalciferol: Cytochrome P450 27 in epidermis completes the set of essential cholecalciferol hydroxylases 109 .…”

Section: Activation and Inactivation Of Hormones In Human Skinmentioning

confidence: 99%

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The human skin as a hormone target and an endocrine gland

Zouboulis¹

2004

161

116

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Hormones influence the development and function of human skin which also produces and releases hormones. Recently attention has been focused on identifying and understanding the complex endocrine properties of human skin, such as expression and function of specific hormone receptors, synthesis of hormones from major classes of compounds used by the body for general purposes, organized metabolism, activation, inactivation and elimination of the hormones in specialized cells of the tissue, exertion of biological activity and release of tissue hormones in the circulation. Specifically, hormones exert their biological effects on the skin through interaction with high-affinity receptors, such as several receptors for peptide hormones and neurotransmitters, steroid and thyroid hormones. Hormones exhibit a wide range of biological activities on the skin with distinct effects caused by growth hormone/insulin-like growth factor-I, neuropeptides, sex steroids, glucocorticoids, retinoids, vitamin D, peroxisome proliferator-activated receptor ligands, eicosanoids, melatonin and serotonin. Human skin produces, activates or inactivates metabolically numerous hormones which are probably important for skin functions but also for functions of the entire human organism, such as sex hormones, especially in aged individuals, insulin-like growth factor and -binding proteins, neuropeptides, prolactin, catecholamines, retinoids, steroids, vitamin D and eicosanoids. These functions are undertaken in most cases by different skin cell populations in a coordinated way, indicating the endocrine autonomy of the skin. Characteristic examples are the metabolic pathways of the corticotropin-releasing hormone/propiomelanocortin axis, steroidogenesis, vitamin D and retinoids. The human skin is, thus, the largest, peripheral endocrine organ.

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Section: Vitamin Dmentioning

confidence: 99%

Section: Activation and Inactivation Of Hormones In Human Skinmentioning

confidence: 99%

The human skin as a hormone target and an endocrine gland

Zouboulis¹

2004

161

116

View full text Add to dashboard Cite

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“…The skin, especially the sebaceous glands, is capable of synthesizing cholesterol – from two-carbon fragments such as acetate [20, 21]– which is utilized in cell membranes, formation of the epidermal barrier, in sebum, and as substrate for steroid hormone synthesis [22]. Skin is also source of corticosteroids [23]and the unique site of vitamin D 3 (cholecalciferol) production [24, 25]. …”

Section: Synthesis Of Hormones In Human Skinmentioning

confidence: 99%

“…In addition, they were found to slowly but constantly form calcitriol from a large reservoir of D 3 . Interestingly, physiological doses of ultraviolet light B radiation at 300 nm induce the conversion of 7-dehydrocholesterol via pre-D 3 and D 3 into calcitriol in the picomolar range in epidermal keratinocytes [25]. Skin can further degrade vitamin D 3 : Cytochrome P450 27 in epidermis completes the set of essential vitamin D 3 hydroxylases [24].…”

Section: Activation and Inactivation Of Hormones In Human Skinmentioning

confidence: 99%

Human Skin: An Independent Peripheral Endocrine Organ

2000

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The historical picture of the endocrine system as a set of discrete hormone-producing organs has been substituted by organs regarded as organized communities in which the cells emit, receive and coordinate molecular signals from established endocrine organs, other distant sources, their neighbors, and themselves. In this wide sense, the human skin and its tissues are targets as well as producers of hormones. Although the role of hormones in the development of human skin and its capacity to produce and release hormones are well established, little attention has been drawn to the ability of human skin to fulfil the requirements of a classic endocrine organ. Indeed, human skin cells produce insulin-like growth factors and -binding proteins, propiomelanocortin derivatives, catecholamines, steroid hormones and vitamin D from cholesterol, retinoids from diet carotenoids, and eicosanoids from fatty acids. Hormones exert their biological effects on the skin through interaction with high-affinity receptors, such as receptors for peptide hormones, neurotransmitters, steroid hormones and thyroid hormones. In addition, the human skin is able to metabolize hormones and to activate and inactivate them. These steps are overtaken in most cases by different skin cell populations in a coordinated way indicating the endocrine autonomy of the skin. Characteristic examples are the metabolic pathways of the corticotropin-releasing hormone/propiomelanocortin axis, steroidogenesis, vitamin D, and retinoids. Hormones exhibit a wide range of biological activities on the skin, with major effects caused by growth hormone/insulin-like growth factor-1, neuropeptides, sex steroids, glucocorticoids, retinoids, vitamin D, peroxisome proliferator-activated receptor ligands, and eicosanoids. At last, human skin produces hormones which are released in the circulation and are important for functions of the entire organism, such as sex hormones, especially in aged individuals, and insulin-like growth factor-binding proteins. Therefore, the human skin fulfils all requirements for being the largest, independent peripheral endocrine organ.

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“…Unlike the loosely regulated hepatic hydroxylation of 25D, the renal 1α-hydroxylation falls under tight control of PTH (parathyroid hormone) and is primarily involved in calcium regulation and signaling. In sites other than the renal tubule (keratinocytes (3), the trophoblastic layer of the placenta (4), IFN-γ stimulated macrophages (5), and granulomata (6), this type of fastidious regulation is either absent or operates very inefficiently. Compared to adults, strict control of renal 1α-hydroxylation and the normal feedback suppression by 1,25D is also less precise in infants.…”

Section: Delineating Vitamin D Sufficiency Insufficiency and Deficiencymentioning

confidence: 99%

The Vitamin D Connection to Pediatric Infections and Immune Function

2009

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ABSTRACT:Over the past 20 y, a resurgence in vitamin D deficiency and nutritional rickets has been reported throughout the world, including the United States. Inadequate serum vitamin D concentrations have also been associated with complications from other health problems, including tuberculosis, cancer (prostate, breast, and colon), multiple sclerosis, and diabetes. These findings support the concept of vitamin D possessing important pleiotropic actions outside of calcium homeostasis and bone metabolism. In children, an association of nutritional rickets with respiratory compromise has long been recognized. Recent epidemiologic studies clearly demonstrate the link between vitamin D deficiency and the increased incidence of respiratory infections. Further research has also elucidated the contribution of vitamin D in the host defense response to infection. However, the mechanism(s) by which vitamin D levels contribute to pediatric infections and immune function has yet to be determined. This knowledge is particularly relevant and timely, because infants and children seem more A fter the discovery that vitamin D deficiency is the cause of nutritional rickets, the emphasis on vitamin D status in children was relegated to a discussion primarily focused on prevention and treatment of the disease. A few early clinicians, however, astutely recognized the increased incidence of respiratory infections among infants and children with rickets. Most presumed, however, that the increased incidence of respiratory infections in these children reflected compromised lung compliance from the rib deformities associated with severe rickets and an overall poor nutritional status. Now epidemiologic studies have identified a link between inadequate vitamin D concentrations and infectious disease. Furthermore, the contribution of vitamin D in host defense against infection has been elucidated. The goal of this study is to provide an overview on the current knowledge available regarding the role of vitamin D in immunologic function and the manifestations of infectious diseases in the pediatric population. Delineating Vitamin D Sufficiency, Insufficiency, and DeficiencyBy definition, vitamin D is not a true vitamin because adequate exposure to sunlight either negates or significantly diminishes the need for dietary supplementation. Instead, this imprecise descriptor refers to a group of steroid molecules also encompassing both vitamin D2 (derived from plants that use ergosterol rather than cholesterol) and vitamin D3 molecules (derived from cholesterol). The human body thus procures vitamin D through two independent pathways: the photochemical action of solar UVB light (ϳ295 to 320 nm) in the skin and some limited dietary sources (1).Given that vitamin D2 is produced by plants, dietary sources (naturally occurring and/or obtained via oral supplementation) are the only means for acquiring it. Vitamin D3, on the other hand, is predominantly procured via the sunlight driven cutaneous reaction described earlier or from dietary sources. For a...

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A Novel Pathway for Hormonally Active Calcitriol

Cited by 9 publications

References 11 publications

The human skin as a hormone target and an endocrine gland

The human skin as a hormone target and an endocrine gland

Human Skin: An Independent Peripheral Endocrine Organ

The Vitamin D Connection to Pediatric Infections and Immune Function

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