Sex steroid metabolism in human peripheral blood mononuclear cells changes with aging.

CONTEXT: Dehydroepiandrosterone (DHEA) mainly exerts indirect action via downstream conversion toward sex steroids within peripheral target cells including immune cells. In vitro DHEA has been shown to enhance IL-2 release from T lymphocytes, whereas it inhibits IL-6 secretion. Conversely, aging is associated with a decline in both DHEA and IL-2, whereas IL-6 increases. OBJECTIVE: The objective of the study was to investigate age-related differences in expression and functional activity of steroidogenic enzymes involved in downstream conversion of DHEA in peripheral blood mononuclear cells (PBMCs). DESIGN: This study was cross-sectional. PARTICIPANTS/SETTING: Healthy young men (n = 8; age range, 23-29 yr) and healthy middle-aged men (n = 8; age range, 52-66 yr) were studied in an academic setting. MEASURES: mRNA expression of steroidogenic enzymes in PBMCs was measured by qualitative and quantitative RT-PCR analysis and enzyme activity assays after incubation of PBMCs with radiolabeled DHEA, 4-androstene-3,17-dione (androstenedione), and testosterone. RESULTS: RT-PCR analysis showed expression of all enzymes required for DHEA conversion toward active androgens and to the immune-stimulatory metabolite androstenediol. Steroid conversion patterns indicated a particularly increased activity of 17beta-hydroxysteroid dehydrogenase type 5 (17beta-HSD5) in the older men, demonstrated by significantly higher conversion rates of DHEA to androstenediol and of androstenedione to testosterone (all P < 0.05). By contrast, conversion of DHEA to androstenedione via 3beta-HSD occurred at a similar rate. Quantitative RT-PCR analysis revealed increased expression of 17beta-HSD 5 mRNA in PBMCs from the older men. CONCLUSIONS: Our results provide evidence for significant changes in sex steroid metabolism by human PBMCs with aging, which may represent an endocrine link to immune senescence.

Beyond adrenal and ovarian androgen generation: Increased peripheral 5 alpha-reductase activity in women with polycystic ovary syndrome.

Hyperandrogenism, a main clinical feature of polycystic ovary syndrome (PCOS), is thought to result from enhanced ovarian and adrenal androgen generation. To investigate the contribution of peripheral steroidogenesis, we used an oral challenge with dehydroepiandrosterone (DHEA) and analyzed its downstream conversion toward androgens in eight women with PCOS (age, 20-32 yr; body mass index, 20-41 kg/m(2)) and eight healthy women matched for age and body mass index. They underwent frequent serum sampling and urine collection for 8 h on three occasions: at baseline, and after 4 d of dexamethasone (Dex; 4 x 0.5 mg/d), followed by ingestion of 100 mg DHEA or placebo. Dex induced similar significant suppression of circulating steroids in both groups. The oral DHEA challenge led to similar significant increases in the area under the concentration-time curve (0-8 h after Dex) of serum DHEA, DHEA sulfate, androstenedione, and testosterone. However, after oral DHEA, PCOS women had significantly higher increases in serum 5 alpha-dihydrotestosterone (P < 0.01), its main metabolite androstanediol glucuronide (P < 0.05), and the 5 alpha-reduced urinary androgen metabolite androsterone (P < 0.05). PCOS women also had significantly higher baseline excretion of 5 alpha-reduced glucocorticoid (P < 0.01) and mineralocorticoid metabolites (P < 0.05). Taken together, these data indicate enhanced peripheral 5 alpha-reductase activity in PCOS. Thus, not only ovary and adrenal, but also liver and peripheral target tissues, significantly contribute to steroid alterations in PCOS.