High production of proinflammatory and Th1 cytokines by dendritic cells from patients with rheumatoid arthritis, and down regulation upon FcgammaR triggering.

OBJECTIVE: To assess whether DC from RA produce altered cytokine levels and whether this is regulated by triggering of Fc gamma receptors (FcgammaR). METHODS: The production of proinflammatory (TNFalpha, IL1, IL6), Th1 (IL12, IFNgamma), and Th2 (IL10) cytokine profiles of immature DC (iDC) from patients with RA and healthy subjects upon triggering of FcgammaR dependent and independent pathways was investigated. iDC, derived from blood monocytes by standardised protocols, were stimulated with immune complexes (IC) at day 6 for 48 hours and, subsequently, for 2 days with LPS in the presence or absence of IC or IFNgamma, resulting in fully matured DC (mDC). IL1, IL6, TNFalpha, IFNgamma, IL12, and IL10 levels in supernatants were measured by ELISA and RIA. RESULTS: mDC from patients with RA showed a markedly increased production of IL1, IL6, TNFalpha, and IL10 compared with DC from healthy donors. Triggering of FcgammaR decreased the production of proinflammatory cytokines IL1, IL12, and IFNgamma by iDC and mDC in RA and controls. The production of IL6 and TNFalpha decreased in patients with RA, whereas it was increased in controls. Triggering of FcgammaR independent mechanisms using IFNgamma increased the production of proinflammatory and Th1 cytokines, which was more pronounced in RA. CONCLUSION: FcgammaR dependent pathways influence cytokine production by DC. A skewed balance towards proinflammatory and Th1 cytokines in RA can, at least partly, be restored by triggering FcgammaR on DC in RA. Insight into the mechanism which determines the FcgammaR balance might lead to new strategies to abrogate Th1 driven inflammatory processes in RA.

Gender differences in rhGH-induced changes in body composition in GH-deficient adults.

In GH-deficient adults, rhGH has pronounced effects on total body water, fat free mass, and fat mass. Recently, we observed a gender difference in IGF-I responsivity to rhGH that was sex steroid dependent. The aim of the present study was to assess the effect of rhGH therapy on body composition parameters with due attention to the gender differences in biological responsiveness to rhGH. Forty-four women [36.9 +/- 11.9 yr (mean +/- SD)] and 33 men (37.2 +/- 13.8 yr) with GH deficiency were studied every 6 months during 2 yr. The treatment goal was to achieve IGF-I levels within the age-adjusted normal range. Total body water, fat free mass, and fat mass were measured by bioimpedantiometry. To reach the treatment goal, the daily rhGH dose (IU/kg/d) had to be significantly higher in women than in men at all time intervals. During rhGH therapy, total body water and fat free mass increased significantly in both men and women (P < or = 0.01 by ANOVA), but changes were more pronounced in men. Fat mass decreased during rhGH treatment and reached its nadir at 6 months, which was more pronounced in men than in women (P = 0.02 by ANOVA). After the initial decrease, fat mass increased again and reached baseline values after 2 yr of treatment. In both men and women, the total body water and fat free mass increases were closely related to the IGF-I increments (P < 0.001 by Pearson's correlation test). The decrease in fat mass correlated significantly with the increase in IGF-I in men (r = -0.89, P < 0.001), not in women. Confirming our earlier data, IGF-I responsivity to rhGH was significantly higher in men than in women at all time intervals (P < 0.01 by ANOVA). Total body water and fat free mass responsivities were also higher in men than in women (P < 0.01 by ANOVA). In conclusion, gender differences in IGF-I responsivities to rhGH are accompanied by gender differences in the extent of body composition changes to rhGH. Probably because of these gender differences in IGF-I responsivity, the increases of total body water and fat free mass to rhGH replacement were greater in men than in women. Remarkably, however, in men, only total body water and fat free mass responses relative to changes in IGF-I increased during the 2 yr of rhGH therapy (P = 0.02 and 0.01, respectively, by ANOVA). In our opinion, this phenomenon might be explained by the increasing target organ sensitivity to IGF-I over time.

Adsorption of erythropoietin and growth hormone to peritoneal dialysis bags and tubing.

OBJECTIVE: To study the adsorption of erythropoietin and growth hormone to dialysis bags and tubing. DESIGN: In vitro study in which radiolabeled erythropoietin and recombinant human growth hormone were added to small-volume (50- and 250-mL) dialysis bags. Recovery was measured after 15-minute dwells. Experiments were performed in triplicate. SETTING: University hospital. RESULTS: Adsorption of erythropoietin and growth hormone was less than 7%. CONCLUSION: Adsorption of erythropoietin and recombinant human growth hormone to dialysis bags and tubing is minimal. This finding provides another argument in favor of intraperitoneal therapy in pediatric peritoneal dialysis.

Selectivity of finasteride as an in vivo inhibitor of 5alpha-reductase isozyme enzymatic activity in the human prostate.

The type II 5alpha-reductase inhibitor finasteride is used in the treatment of benign prostatic hyperplasia (BPH), reducing local production of the growth promoting androgen dihydrotestosterone (DHT). The effect of prolonged treatment with this time-dependent irreversible inhibitor on the recently described prostatic type I 5alpha-reductase, however, is not clear. Therefore, we assessed the effects of 5 mg. finasteride per day for 6 months on prostatic 5alpha-reductase isozymes, and prostatic tissue composition and androgen content of patients suffering from BPH. In prostatic tissue from these patients, the type II enzymatic activity is inhibited 100-fold compared with tissues obtained from placebo treated patients. The type II immunoreactivity is up regulated 2-fold. The type I isozyme is inhibited 3-fold and potentially still contributes to DHT production. In conclusion, finasteride is a selective type II inhibitor in vivo. Further research is warranted to assess the possibly distinct roles of the 5alpha-reductase isozymes in the normal prostate, in BPH, and during finasteride treatment.

Identification and partial characterization of two steroid 5 alpha-reductase isozymes in the canine prostate.

BACKGROUND: The dog has been extensively used as an in vivo model to test the pharmacokinetics and effects on pathological prostatic growth of 5 alpha-reductase inhibitors. However, no information is available on the existence or characteristics of canine 5 alpha-reductase isozymes. METHODS: The 5 alpha-reduction of testosterone is analyzed in dog prostatic homogenates. Three human-specific inhibitors are tested for their activity against dog 5 alpha-reductase. RESULTS: Two pH optima of 5 alpha-reductase activity in dog prostatic homogenates are described, comparable to the pH optima of rat and human 5 alpha-reductase isozymes. Kinetic analysis of 5 alpha-reductase enzymatic activity at pH 7.0 revealed isozymes with a low apparent affinity constant (Km = 2.67 nM) and a high apparent affinity constant (Km = 1.23 microM). These apparent affinity constants compare favorably to the human and rat isozymes types II and I, respectively. The human type II inhibitor finasteride selectively inhibited the low Km isozyme, whereas the human type I inhibitor MK386 preferentially inhibited the high Km isozyme. The human type I inhibitor LY306089 was nonspecific for the dog isozymes. CONCLUSIONS: We postulate that the high and low Km isozymes described here represent the dog type I and type II 5 alpha-reductase isozymes, respectively.