Interleukin-1 inhibits Leydig cell steroidogenesis primarily by decreasing 17 alpha-hydroxylase/C17-20 lyase cytochrome P450 expression.
Macrophage-secreted cytokines, such as interleukin-1 (IL-1), have been shown to modulate Leydig cell function. The present study examined the effect of recombinant murine IL-1 alpha on Leydig cell steroidogenesis and its mechanism of action. Addition of IL-1 to macrophage-depleted primary cultures of mouse Leydig cells caused a dose-dependent decrease in cAMP-dependent testosterone production and 17 alpha-hydroxylase/C17-20 lyase (P450c17) mRNA levels. Chronic treatment (48 h) of Leydig cells in culture with 50 microM 8-bromo-cAMP (8-Br-cAMP) resulted in a 60-fold increase in testosterone production. Treatment with 8-Br-cAMP plus 0.2 and 2 U/ml IL-1 decreased testosterone production to 63 +/- 14% and 41 +/- 19%, respectively, while 5, 10, and 20 U/ml IL-1 decreased testosterone production to less than 5% that of cells treated with 8-Br-cAMP alone. Chronic treatment with IL-1 plus 8-Br-cAMP caused a shift in steroid production from testosterone to progesterone, but total steroid production (the sum of testosterone plus progesterone) was unaffected by IL-1 treatment. Treatment with 8-Br-cAMP alone caused a marked increase in P450c17 mRNA levels compared to that in control cultures, where P450c17 mRNA was undetectable. IL-1 caused a dose-dependent decrease in 8-Br-cAMP-stimulated P450c17 levels (0.2 U/ml by 31 +/- 9%, 2 U/ml by 82 +/- 12%, and 10 or 20 U/ml by 100% compared to that in cells treated with 8-Br-cAMP alone). In contrast to the effect on P450c17 mRNA, only the highest concentrations of IL-1 (10 and 20 U/ml) had any effect on cholesterol side-chain cleavage enzyme (P450scc) mRNA levels (53 +/- 16% and 38 +/- 20% decreases, respectively). The inhibitory effect of IL-1 on 8-Br-cAMP-stimulated P450c17 expression was reversible. Within 12 h after the removal of IL-1, P450c17 mRNA was restored to 24%; after 24 h, to 36%; after 36 h, to 65%; and after 48 h, to 84% of that with 8-Br-cAMP alone. P450c17 expression was more sensitive to IL-1-mediated inhibition than P450scc; therefore, inhibition of P450c17 is most likely primarily responsible for the observed inhibitory effects of IL-1 on Leydig cell testosterone production.
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Department of Physiology and Biophysics, University of Illinois College of Medicine, Chicago 60680.
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D002478:Cells, Cultured; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000032:analysis / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D007375:Interleukin-1 / Q000494:pharmacology*; D007985:Leydig Cells / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism*; D008297:Male; D051379:Mice; D011374:Progesterone / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D011863:Radioimmunoassay; D013254:Steroid 17-alpha-Hydroxylase / Q000032:analysis* / Q000235:genetics / Q000502:physiology; D013739:Testosterone / Q000378:metabolism*
D007375:Interleukin-1; D012333:RNA, Messenger; D015124:8-Bromo Cyclic Adenosine Monophosphate; D013739:Testosterone; D011374:Progesterone; D013254:Steroid 17-alpha-Hydroxylase; D002786:Cholesterol Side-Chain Cleavage Enzyme