Vitamins as Hormones

J. Reichrath; B. Lehmann; C. Carlberg; J. Varani; C. C. Zouboulis

doi:10.1055/s-2007-958715

Hormone and Metabolic Research, Table of Contents

Horm Metab Res 2007; 39(2): 71-84
DOI: 10.1055/s-2007-958715

Review

Vitamins as Hormones

J. Reichrath¹ , B. Lehmann² , C. Carlberg³ ^, ⁴ , J. Varani⁵ , C. C. Zouboulis⁶ ^, ⁷

¹Department of Dermatology, The Saarland University Hospital, Homburg, Germany
²Department of Dermatology, Medical School “Carl Gustav Carus”, Dresden University of Technology, Dresden, Germany
³Department of Biochemistry, University of Kuopio, Kuopio, Finland
⁴Life Science Research Units, Université du Luxembourg, Luxembourg
⁵Department of Pathology, The University of Michigan, Ann Arbor, MI, U.S.A.
⁶Departments of Dermatology and Immunology, Dessau Medical Center, Dessau, Germany
⁷Laboratory of Biogerontology, Dermato-Pharmacology and Dermato-Endocrinology, Institute of Clinical Pharmacology and Toxicology, Charité Universitaetsmedizin Berlin, Campus Benjamin Franklin, Berlin, Germany

Abstract

Vitamins A and D are the first group of substances that have been reported to exhibit properties of skin hormones, such as organized metabolism, activation, inactivation, and elimination in specialized cells of the tissue, exertion of biological activity, and release in the circulation. Vitamin A and its two important metabolites, retinaldehyde and retinoic acids, are fat-soluble unsaturated isoprenoids necessary for growth, differentiation and maintenance of epithelial tissues, and also for reproduction. In a reversible process, vitamin A is oxidized in vivo to give retinaldehyde, which is important for vision. The dramatic effects of vitamin A analogues on embryogenesis have been studied by animal experiments; the clinical malformation pattern in humans is known. Retinoic acids are major oxidative metabolites of vitamin A and can substitute for it in vitamin A-deficient animals in growth promotion and epithelial differentiation. Natural vitamin A metabolites are vitamins, because vitamin A is not synthesized in the body and must be derived from carotenoids in the diet. On the other hand, retinoids are also hormones - with intracrine activity - because retinol is transformed in the cells into molecules that bind to and activate specific nuclear receptors, exhibit their function, and are subsequently inactivated. The mechanisms of action of natural vitamin A metabolites on human skin are based on the time- and dose-dependent influence of morphogenesis, epithelial cell proliferation and differentiation, epithelial and mesenchymal synthetic performance, immune modulation, stimulation of angiogenesis and inhibition of carcinogenesis. As drugs, vitamin A and its natural metabolites have been approved for the topical and systemic treatment of mild to moderate and severe, recalcitrant acne, photoaging and biologic skin aging, acute promyelocytic leukaemia and Kaposi's sarcoma. On the other hand, the critical importance of the skin for the human body's vitamin D endocrine system is documented by the fact that the skin is both the site of vitamin D₃- and 1,25-dihydroxyvitamin D₃ [1, 25(OH)₂D₃]-synthesis and a target organ for 1,25(OH)₂D₃. 1,25(OH)₂D₃ is not only essential for mineral homeostasis and bone integrity, but also for numerous further physiologic functions including regulation of growth and differentiation in a broad variety of normal and malignant tissues, including cells derived from prostate, breast and bone. In keratinocytes and other cell types, 1,25(OH)₂D₃ regulates growth and differentiation. Consequently, vitamin D analogues have been introduced for the treatment of the hyperproliferative skin disease psoriasis. Other newly detected functions of vitamin D analogues include profound effects on the immune system as well as protection against cancer and other diseases, including autoimmune and infectious diseases, in various tissues. Current investigation of the biological effects of vitamin D analogues are likely to lead to new therapeutic applications that, besides cancer prevention, may include the prevention and treatment of infectious as well as of inflammatory skin diseases. This review summarizes existing knowledge on vitamins A and D, the major vitamin-hormones of the skin.

Keywords

vitamins - vitamin A - vitamin D - hormones - retinoids - skin protection

Full Text

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Correspondence

C. C. Zouboulis

Departments of Dermatology and Immunology

Dessau Medical Center

Auenweg 38

06847 Dessau

Germany

Phone: +49/340/501 40 00

Fax: +49/340/501 40 25

Email: christos.zouboulis@klinikum-dessau.de