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Dehydroepiandrosterone (DHEA) is a ubiquitous adrenal hormone with immunomodulatory effects such as inhibition of the production of monokines. Whether DHEA itself or the downstream steroids are the immunomodulatory effector hormones in target cells is not known. In this study, we investigated the conversion of DHEA to downstream steroid hormones in target macrophages. Within 1 day of culture with radiolabeled DHEA, monocyte-derived macrophages converted DHEA to significant amounts of Delta5-derivatives such as 16OH-DHEA, 3beta, 17beta-androstenediol (A'diol), and 3beta,16alpha, 17beta-androstenetriol (A'triol). However, the production of Delta4-steroids (androstenedione (A'dione), testosterone (T), and 16OH-T) and estrogens (estrone, estradiol, and estriol) was relatively low. Further cultivation of macrophages for 5 days with radiolabeled DHEA resulted in a significant (P<0.05) increase of the molar amounts of A'triol (P=0.012), 16OH-T (P=0.008), and estriol (P=0.003). In contrast to monocyte-derived macrophages, monocytes did not express aromatase mRNA, which was demonstrated by RT-PCR (P<0.01). Furthermore, DHEA in macrophages significantly inhibited one of the downstream converting enzymes, the aromatase, which was not demonstrated in the presence of the typical macrophage activator, lipopolysaccharide (LPS) (P<0.01). In conclusion, conversion of DHEA to physiologically relevant amounts of Delta5- and Delta4-steroids and estrogens was demonstrated in monocyte-derived macrophages. The conversion depends on maturation of monocytes and local factors such as the presence of LPS. The conversion of DHEA leads to an increase of downstream effector hormones in target macrophages which may be an important factor for local immunomodulation.

Dehydroepiandrosterone (DHEA) and DHEA sulphate (DHEAS) inhibit T-helper lymphocyte type 2 immune reactions and exert anti-inflammatory effects in some chronic inflammatory diseases. Both DHEA and, in particular, DHEAS levels are dramatically decreased in chronic inflammatory diseases whereas cortisol levels remain stable or are elevated. However, the time course of cortisol relative to DHEA production is not known. We tested whether administration of endotoxin to healthy male subjects can induce an early predominance of cortisol relative to DHEA and DHEAS. It is demonstrated that endotoxin induces a dose-dependent increase of cortisol in relation to DHEA (no effect at 0.2 ng endotoxin/kg body weight (b.w.), clear effect at 0.4 and 0.8 ng/kg b.w., p<0.05) and DHEAS (tested at 0.4 ng/kg b.w., P=0.014). The increase of cortisol relative to DHEA appears 4 h after endotoxin injection and 2 h after a strong increase of interleukin (IL)-6 relative to tumour necrosis factor (TNF). In addition, an increase of cortisol relative to 17OH-progesterone was observed. The ratio of serum IL-6/TNF was positively correlated with the ratio of serum cortisol/DHEA (R(Rank)=0.472, P=0.041) and serum cortisol/17OH-progesterone (R(Rank)=0.514, P=0.048). In conclusion, dissociation of cortisol relative to DHEA, DHEAS or 17OH-progesterone appears very early during a systemic inflammatory response which is associated with an increase of IL-6 relative to TNF. As in chronic inflammatory diseases, during an acute inflammatory response with endotoxin, these physiological hormone changes are probably necessary to achieve adequate cortisol levels at the expense of adrenal androgens.

The adipocyte-derived hormone, leptin, has been implicated in the regulation of appetite, weight gain and glucose homeostasis as well as in liver fibrogenesis, hematopoiesis and immune function. No previous reports have clearly defined pathologically elevated or decreased serum leptin levels for Caucasian adults. The aim of this study was to define and characterize subjects with relative hyper- and hypoleptinemia in a large population-based German cohort. Percentiles of leptin levels by body mass index (BMI) were calculated from 4971 adult Germans, and the participants with leptin levels above the 95th and below the 5th percentile were defined as relatively hyperleptinemic and relatively hypoleptinemic, respectively, for their BMI. These participants were compared with the intermediate group with respect to anthropometric and clinical data and parameters of glucose and iron metabolism, lipid status, renal, adrenal and reproductive function. Relatively hyperleptinemic participants (HL) showed higher insulin, c-peptide, and total cholesterol levels than the hypoleptinemic subjects; in males, ferritin levels were higher and testosterone levels lower in the HL group. In conclusion, we report the first percentile curves for serum leptin by BMI in a large Caucasian population. Relatively low leptin values may be associated with a lower metabolic risk than relatively high serum leptin values.