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a Institute of Biochemistry II, Hospital of the Friedrich-Schiller-University, 07740 Jena, Germany b Department of Internal Medicine I, University Hospital Regensburg, 93042 Regensburg, Germany c Department of Orthopedic Surgery, University Regensburg, Bavarian Red Cross Hospital, 93077 Bad Abbach, Germany
Key Words: steroid metabolism • synovial cell • rheumatoid arthritis • testosterone • estradiol • DHEA • 7  -hydroxy-DHEA • dihydro-testosterone • androsterone
Address for correspondence: Dr. Martin Schmidt, Institute of Biochemistry II, Hospital of the Friedrich-Schiller-University, 07740 Jena, Germany. Voice: +49-3641-938-683; fax: +49-3641-938-682. e-mail: Schmidt{at}mti.uni-jena.de
The incidence of autoimmune diseases is higher in females than in males. In both sexes, adrenal hormones, that is, glucocorticoids, dehydroepiandrosterone (DHEA), and androgens, are inadequately low in patients when compared to healthy controls. Hormonally active androgens are anti-inflammatory, whereas estrogens are pro-inflammatory. Therefore, the mechanisms responsible for the alterations of steroid profiles in inflammation are of major interest. The local metabolism of androgens and estrogens may determine whether a given steroid profile found in a subject's blood results in suppression or promotion of inflammation. The steroid metabolism in mixed synovial cells, fibroblasts, macrophages, and monocytes was assessed. Major focus was on cells from patients with rheumatoid arthritis (RA), while cells from patients with osteoarthritis served as controls. Enzymes directly or indirectly involved in local sex steroid metabolism in RA are: DHEA-sulfatase, 3
 -hydroxysteroid dehydrogenase, 17-hydroxysteroid dehydrogenase, and aromatase (CYP19), which are required for the synthesis of sex steroids from precursors, 5-reductase and 16-hydroxylase, which can be involved either in the generation of more active steroids or in the pathways leading to depletion of active hormones, and 3-reductase and 7-hydroxylase (CYP7B), which unidirectionally are involved in the depletion of active hormones. Androgens inhibit aromatization in synovial cells when their concentration is sufficiently high. As large amounts of estrogens are formed in synovial tissue, there may be a relative lack of androgens. Production of 5-reduced androgens should increase the local anti-inflammatory activity; however, it also opens a pathway for the inactivation of androgens. The data discussed here suggest that therapy of RA patients may benefit from the use of nonaromatizable androgens and/or the use of aromatase inhibitors.
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