Stimulatory Effect Of IL-1beta Research Articles

Effect of interleukin-1β on growth hormone gene expression and its possible molecular mechanism in rat MtT/S somatotroph cells

To elucidate the effect of interleukin-1 beta (IL-1 beta) on human growth hormone (hGH) gene expression in a rat somatotropic pituitary cell line MtT/S. Stably transfected MtT/S cells were firstly established by transfecting 484-Luc1 plasmid which contained hGH gene promoter -484 to +30 bp and luciferase reporter gene. The effect of IL-1 beta on hGH gene expression was determined by assaying the luciferase activities. RT-PCR method was also used to determine whether IL-1 recepor mRNA was expressed in MtT/S cells. The 10(3) U/mL IL-1 beta stimulated secretion and synthesis of GH, and promoted the 5'-promoter activity of GH gene in stably transfected MtT/SGL cells with the action of 1.38 times above the control. Among inhibitors of signaling transduction pathways, mitogen-activated protein kinase kinase (MAPKK/MEK) inhibitor PD98059 (40 micromol/L) and p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 (5 micromol/L) completely blocked the stimulatory effect of IL-1 beta, and phosphatidylinositol-3-kinase (PI3-K) inhibitor LY294002 partly abolished the effect of IL-1 beta. Western blot analysis further confirmed the activation of phosphorylated MEK and p38 MAPK in MtT/SGL cells. Neither over-expression of Pit-1 nor inhibition of Pit-1 expression affected induction of hGH promoter activity by IL-1 beta. A series of deletion constructs of hGH promoter were created to identify the DNA sequence that mediated the effect of IL-1 beta, and results showed that the stimulatory effect of IL-1 beta was abolished following deletion of the -196 to -132 bp fragment. IL-1 beta promotes GH secretion and synthesis in rat MtT/S somatotroph cells. The stimulatory effect of IL-1 beta on hGH gene promoter appears to require the activation of MEK, p38 MAPK, PI3-K, and a fragment of promoter sequence that spans the -196 to -132 bp of the gene, but it may be unlinked with Pit-1 protein.

Gene expression profiling of human synovial sarcoma cell line (Hs701.T) in response to IL-1β stimulation

Synovial sarcoma (SS) is a malignant mesenchymal tumor that accounts for 5-10% of all soft tissue sarcoma. IL-1beta, a pleiotrophic cytokine, has been found in the tumor microenvironment which plays crucial roles in the pathogenesis of tumors. In this study, we used Hs701.T as a cellular model to study the short-term (4-h) and long-term (48-h) stimulatory effect of IL-1beta on cell proliferation and differential gene expression. The results showed that IL-1beta can stimulate cell proliferation through activation of NF-kappaB and AP-1 transcription factors; sequentially triggers the expression of genes related to tumor progression. The microarray data indicated that most of the up-regulated genes were related to tumor progression. Five candidate genes which are involved in the mediation of proliferation (IL-6), apoptosis (Hsp27 and Daxx), and angiogenesis (PlGF and SPARC) were further validated by RT-PCR. These findings may be useful for understanding the pathogenesis of synovial sarcoma.

Nitric oxide down‐regulates the expression of the catalytic NADPH oxidase subunit Nox1 in rat renal mesangial cells

Glomerular mesangial cells can produce high amounts of nitric oxide (NO) and reactive oxygen species (ROS). Here we analyzed the impact of NO on the ROS-generating system, particularly on the NADPH oxidase Nox1. Nox1 mRNA and protein levels were markedly decreased by treatment of mesangial cells with the NO-releasing compound DETA-NO in a concentration- and time-dependent fashion. By altering the cGMP signaling system with different inhibitors or activators, we revealed that the effect of NO on Nox1 expression is at least in part mediated by cGMP. Analysis of a reporter construct comprising the 2547 bp of the nox1 promoter region revealed that a stimulatory effect of IL-1beta on nox1 transcription is counteracted by an inhibitory effect of IL-1beta-evoked endogenous NO formation. Moreover, pretreatment of mesangial cells with DETA-NO attenuated platelet-derived growth factor (PDGF)-BB or serum stimulated production of superoxide as assessed by real-time EPR spectroscopy and dichlorofluorescein formation. Transfection of mesangial cells with siRNAs directed against Nox1 and Nox4 revealed that inhibition of Nox1, but not Nox4 expression, is responsible for the reduced ROS formation by NO. Obviously, there exists a fine-tuned crosstalk between NO and ROS generating systems in the course of inflammatory diseases.

Endometrial stromal cells undergoing decidualization down-regulate their properties to produce proinflammatory cytokines in response to interleukin-1 beta via reduced p38 mitogen-activated protein kinase phosphorylation.

The decidualized endometrium plays a role in regulating trophoblast invasion for successful implantation and maintenance of pregnancy. IL-1 beta, a proinflammatory cytokine, has been suggested to play a role in this process. Recently, several lines of evidence indicate the importance of p38 MAPK in various inflammatory responses. We investigated whether endometrial stromal cells (ESC) change their inflammatory responses to IL-1 beta as related to p38 MAPK phosphorylation during the process of decidualization. ESC were decidualized by the treatment with progesterone for 9 d, as determined as such by an increase in the production of prolactin and cAMP by the cells. Whereas IL-1 beta increased the production of IL-6, IL-8, and monocyte chemotactic protein-1, and expression of cyclooxygenase-2 mRNA in ESC cultured without treatment, the stimulatory effects of IL-1 beta were reduced in the decidualized cells. Treatment with SB202190, a p38 MAPK inhibitor, also reduced the stimulatory effects of IL-1 beta in nondecidualized ESC. P38 MAPK phosphorylation was increased by IL-1 beta in nondecidualized ESC, whereas the IL-1 beta-induced increase was suppressed in the decidualized cells. Treatment with 8-bromo-cAMP reduced IL-1 beta-induced phosphorylation of p38 MAPK in nondecidualized ESC. In contrast, treatment with H89, a protein kinase A inhibitor, reversed a reduction in IL-1 beta-induced p38 MAPK phosphorylation in the decidualized cells. In summary, decidualization seems to be a process during which endometrial cells diminish their response to IL-1 beta, a known key factor for implantation, leading to the down-regulation of inflammation-like events, which may be relevant to controlled trophoblast invasion. The altered property of decidualized cells is thought to be caused by attenuation of IL-1 beta-induced p38 MAPK phosphorylation in a way that involves the activation of the cAMP/protein kinase A pathway.

Interleukin-1beta induces glycosaminoglycan synthesis via the prostaglandin E2 pathway in cultured human cervical fibroblasts.

The aim of this study was to identify, in cultured human cervical fibroblasts, the mechanisms by which interleukin (IL)-1beta induces the synthesis of glycosaminoglycans (GAG) and to explore the putative role of prostaglandin E(2) (PGE(2)) in this process. Exposure of the cells for 24 h to IL-1beta induced a significant (P < 0.05) dose-dependent increase in GAG synthesis. IL-1beta (1 ng/ml) induced the expression of cyclooxygenase-2 (COX-2) protein 6 h after treatment, accompanied by a 7.5-fold increase in PGE(2) production. We confirmed that NS398, a selective COX-2 inhibitor, dose-dependently blocked PGE(2) augmentation following IL-1beta treatment. AH23848, the selective EP(4) receptor antagonist, completely abolished IL-1beta-induced GAG synthesis, whereas AH6809, an EP(2) receptor antagonist, had no effect on the stimulatory effects of IL-1beta. Furthermore, we demonstrated that 6 h exposure to IL-1beta induced a notable increase in EP(4) receptor mRNA expression and a decrease in EP(1) receptor mRNA but had no effect on the expression of EP(2) and EP(3) receptor transcripts. In conclusion, these findings indicate that IL-1beta not only induced GAG synthesis by increasing COX-2 protein expression and the subsequent PGE(2) production but also enhanced the responsiveness of cervical fibroblasts to PGE(2) by selectively up-regulating EP(4) receptor mRNA expression. These results suggest that PGE(2) may regulate human cervical ripening in an autocrine/paracrine manner via EP(4) receptors.

Osteoprotegerin levels increased by interleukin-1beta in human periodontal ligament cells are suppressed through prostaglandin E(2) synthesized de novo.

Osteoprotegerin (OPG) is a novel tumor necrosis factor receptor superfamily that inhibits osteoclast differentiation, activity, and survival. Interleukin-1beta (IL-1beta) increases OPG expression. IL-1beta also increases prostaglandin E(2) (PGE(2)) production and stimulates bone resorption. In the present study, we examined the involvement of PGE(2) in IL-1beta-induced increases in OPG levels in human periodontal ligament cells (HPL cells) in an effort to clarify apparently conflicting IL-1beta actions on bone resorption and understand IL-1beta-induced increases in secretion of OPG and PGE(2) in HPL cells. 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole, a mRNA synthesis inhibitor, partly inhibited the increase in OPG mRNA levels induced by IL-1beta. Cycloheximide, a protein synthesis inhibitor, enhanced the stimulatory effect of IL-1beta. Etodolac, a selective cyclooxygenase-2 inhibitor, suppressed the increase in PGE(2) levels. Furthermore, etodolac reinforced the promotion of OPG expression by IL-1beta at the mRNA and protein levels. PGE(2) added to cultures of HPL cells decreased OPG mRNA levels in a dose- and time- dependent manner. These findings suggest that the increase in OPG levels induced by IL-1beta in HPL cells is suppressed through PGE(2) synthesized de novo.

Cytokine-induced Down-regulation of zfm1/Splicing Factor-1 Promotes Smooth Muscle Cell Proliferation

One hallmark of inflammation is the proliferation of bystander cells such as vascular smooth muscle cells (SMC), a process governed by growth factors and cytokines. Whereas cytokine induction of gene products promoting inflammation and proliferation is well characterized, little is known about the concomitant down-regulation of potentially counter-regulatory gene products in these cells. By employing the suppression subtractive hybridization-PCR technique, RNA isolated from rat aortic SMC treated with the cytokines interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) was subtracted from RNA of control cells. Eleven genes were identified, the expression of which fell by 44-77%. One, the transcriptional repressor splicing factor-1 or zfm1, was characterized further. Antisense oligonucleotide suppression of zfm1 protein synthesis mimicked the stimulatory effects of IL-1 beta and TNF alpha on SMC proliferation and expression of the chemokine MCP-1 and the vascular cell adhesion molecule-1. Moreover, in an in vivo mouse model of atherosclerosis, zfm1 abundance was decreased in proliferating arterial SMC. These findings suggest a role for zfm1 in controlling both proliferation and expression of pro-inflammatory gene products in SMC. Therefore, cytokine-induced down-regulation of zfm1 expression may contribute to the pathogenesis of hyperproliferative inflammatory diseases.

Interleukin 1 upregulates ovarian prostaglandin endoperoxide synthase-2 expression: evidence for prostaglandin-dependent/ceramide-independent transcriptional stimulation and for message stabilization.

We have recently documented a marked dependence of ovarian prostaglandin endoperoxide synthase (PGS)-2 transcripts, proteins, and activity on interleukin (IL) 1, a putative intermediary in the ovulatory cascade. The purpose of the present study was to characterize the cellular and molecular mechanisms underlying the ability of IL-1beta to upregulate the steady-state levels of ovarian transcripts corresponding to PGS-2. Results of studies designed to enrich or deplete nitric oxide strongly suggest that the stimulatory effect of IL-1beta on ovarian PGS-2 expression is independent of nitric oxide. Utilization of a series of agents designed to simulate or enhance transduction via the sphingomyelin ceramide cycle suggests that the long-term stimulatory effect of IL-1beta on ovarian PGS-2 gene expression is independent of ceramide. In contrast, inhibition of prostaglandin biosynthesis with a series of distinct inhibitors suggests that the ability of IL-1beta to upregulate ovarian PGS-2 transcripts is due, if only in part, to the generation of endogenous prostaglandin estradiol-17beta (E(2)). Inhibition of protein biosynthesis suggested that the IL-1beta-induced PGS-2 gene expression required de novo protein biosynthesis. Our findings revealed substantial IL-1beta-mediated stabilization of PGS-2 transcripts, as assessed by a threefold increase in the half-life of the message. We have also observed the ability of IL-1beta to upregulate the transcription of PGS-2 promoter constructs subjected to transient transfection into whole-ovarian dispersates (twofold increase as assessed by activation of the luciferase reporter gene). Taken together, these findings suggest that the stimulatory effect of IL-1beta on PGS-2 expression is 1) independent of nitric oxide as well as ceramide, 2) dependent on prostaglandin E(2), 3) contingent on de novo protein biosynthesis, and 4) accounted for by both increased transcription and message stabilization. These observations provide indirect support for the hypothesis that IL-1beta, acting in part through PGS-2 (an obligatory ovulatory principal), may constitute a key intermediary in the ovulatory cascade.

The Anti-inflammatory Cytokine, Interleukin (IL)-10, Blocks the Inhibitory Effect of IL-1β on Long Term Potentiation: A ROLE FOR JNK

Several effects of the proinflammatory cytokine, interleukin-1 beta (IL-1 beta), have been described in the central nervous system, and one area of the brain where marked changes have been reported is the hippocampus. Among these changes are an IL-1 beta-induced inhibition of long term potentiation (LTP) in perforant path-granule cell synapses and an attenuation of glutamate release in synaptosomes prepared from the hippocampus. Evidence suggests that, at least in circulating cells, the anti-inflammatory cytokine, IL-10, antagonizes certain effects of IL-1. We investigated the effect of IL-10 on IL-1 beta-induced inhibition of LTP and glutamate release. The evidence presented indicates that IL-1 beta stimulates the stress-activated protein kinase, c-Jun-activated protein kinase (JNK), and IL-1 receptor-associated kinase, which may explain its inhibitory effect on release and LTP, and that IL-10 reversed the IL-1 beta-induced stimulation of JNK activity and inhibition of release and LTP. We observed that IL-10 abrogated the stimulatory effect of IL-1 beta on superoxide dismutase activity and reactive oxygen species production, whereas the H(2)O(2)-induced inhibition of LTP was also blocked by IL-10. We present evidence that suggests that the action of IL-10 may be mediated by its ability to induce shedding of the IL-1 type I receptor.

Prostanoid stimulation of cytokine production in an amnion-derived cell line: evidence of a feed-forward mechanism with implications for term and preterm labor.

To test the hypothesis that amnion cytokine production might be regulated by prostanoids. Amnion-derived WISH cells were treated with a range of prostanoids and their effects on production of interleukin (IL)-6 and IL-8 were determined by enzyme-linked immunosorbent assay and Northern analysis. The effects of thromboxane inhibitors on cytokine production by term primary amnion explants also were examined. Prostaglandin (PG)A2, PGD2, PGF2 alpha, PGE2, PGJ2, and the PGI2 analogue carbaprostacyclin (1-1000 nmol/L) exhibited no significant effects on cytokine production. However, the thromboxane A2 (TXA2) agonist U46619 and carbocyclic (c)TXA2 both stimulated WISH cytokine production with similar potencies under basal or cytokine-stimulated conditions. Significant stimulation of IL-6 production was observed at concentrations > or = 8 nmol/L (P < .05 by analysis of variance), whereas IL-8 production was stimulated significantly but to a lesser extent. The effects of U46619 and cTXA2 were rapid; maximal stimulation of cytokine production occurred within 4 to 8 hours of treatment. U46619 augmented IL-1 beta-stimulated IL-6 and IL-8 mRNA expression within 2 hours of treatment. In amnion explants inhibitors of TX synthesis and action abrogated the stimulatory effects of IL-1 beta on cytokine production. These results are consistent with the presence of a feed-forward loop in amnion involving TXA2 and cytokines, which could play a significant role in the progression of the inflammatory response involved in the mechanism of infection-driven preterm labor.

Ovarian interleukin-1 receptor antagonist in rats: gene expression, cellular localization, cyclic variation, and hormonal regulation of a potential determinant of interleukin-1 action.

It is hypothesized that the intraovarian interleukin (IL)-1 system plays a prominent role in the regulation of follicular development and ovulation. A central component of the intraovarian IL-1 system is the IL-1 receptor antagonist (IL-1RA), a protein acting as a pure IL-1 receptor antagonist and one for which intracellular (icIL-1RA) and secretory (sIL-1RA) varieties have been described. It was the objective of this study to explore rat ovarian IL-1RA gene expression, to establish the identity and relative abundance of its alternative transcripts, to study its cellular localization, to determine its cyclic variation, and to assess its hormonal regulation. Protected IL-1RA cDNA fragments corresponding to either sIL-1RA or icIL-1RA were barely detectable in untreated whole ovarian tissue of immature rat origin. However, sIL-1RA transcripts reached a maximal value (3.3-fold increase over untreated control values; p < 0.05) 12 h after hCG administration (time of projected ovulation). In situ hybridization localized IL-1RA to mural, antral, and cumulus granulosa cells. Modestly intense staining was also apparent in oocytes. The basal pattern of sIL-1RA expression by cultured whole ovarian dispersates was characterized by a spontaneous increase to a peak value at 4 h. The early (4 h) sIL-1RA burst proved IL-1-, nitric oxide-, and protein biosynthesis-independent. However, treatment with IL-1beta led to a secondary sIL-1RA peak at 48 h, an effect that was substantially reversed by IL-1RA. This stimulatory effect of IL-1beta on IL-1RA expression proved relatively specific, and nitric oxide independent, but contingent upon de novo protein biosynthesis. The in vitro expression of icIL-1RA was barely detectable. Taken together, these in vivo and in vitro observations 1) document the rat ovary as a site of IL-1RA (sIL-1RA > cIL-1RA) expression, 2) localize the relevant transcripts to the granulosa cell, 3) disclose peak expression at the time of ovulation, and 4) establish IL-1 dependence.

The effect of cytokines on parathyroid hormone-related protein (PTH-rP) production in human amnion cells.

In the present study, the effects of various cytokines on parathyroid hormone-related protein (PTH-rP) production and PTH-rP mRNA expression in human amnion cells were studied. Immunoreactive (ir) PTH-rP was measured by immunoradiometric assay and the expression of PTH-rP mRNA was determined by Northern blot analysis. The addition of interleukin-1beta (IL-1beta, 10 ng/ml) and IL-6 (10 ng/ml) in culture medium for 24 hours resulted in a significant increase in ir-PTH-rP levels by 1.5 and 1.6 fold, respectively. The effects of these agents were dose dependent. In contrast, IL-2 (10 ng/ml) and IL-8 (10 ng/ml) showed no effect on the production of ir-PTH-rP from amnion cells. Treatment with IL-1beta or IL-6 for 6 hours increased the expression of PTH-rP mRNA in amnion cells. The stimulatory effect of IL-1beta was reduced by IL-1 receptor antagonist (IL-1Ra) in a dose dependent manner. Both tetradecanoyl phorbol acetate (TPA), and forskolin increased PTH-rP mRNA levels and the PTH-rP production in amnion cells, and the effect of TPA was much greater than that of forskolin. The findings of the present study suggest of the participation of inflammatory cytokines for the regulation of PTH-rP production in human amnion cells.

Interleukin-1beta administered intracerebroventricularly stimulates the release of noradrenaline in the hypothalamic paraventricular nucleus via prostaglandin in the rat.

We evaluated the effect of intracerebroventricular (i.c.v.) administration of interleukin (IL)-1beta on the rectal temperature and the release of noradrenaline (NA) in the hypothalamic paraventricular nucleus (PVN) of the rat. IL-1beta increased rectal temperature at doses ranging from 300 pg to 300 ng, whereas it, at doses ranging from 3 ng to 300 ng, significantly stimulated the release of NA in the PVN measured by intracerebral microdialysis. The stimulatory effect of IL-1beta on the release of NA was blocked by the subcutaneous injection of indomethacin. These findings suggest that IL-1beta stimulates the release of NA in the PVN via prostaglandin, and that the release of NA in the PVN is not necessarily related to the increase in body temperature.

Elevated levels of serum interleukin-1β in combat-related posttraumatic stress disorder

Levels of serum interleukin-1 beta (IL-1 beta) and soluble interleukin-2 receptor (sIL-2R) were assessed in 19 male patients with combat-related posttraumatic stress disorder (PTSD) in comparison to 19 age- and sex-matched healthy volunteers. Serum IL-1 beta levels (but not sIL-2R) were significantly higher (p < .001) in the PTSD patients than in the controls. IL-1 beta levels did not correlate with cortisol levels, severity of PTSD, anxiety, depressive symptoms, or alexithymia score; however, they did correlate significantly (r = .54, p < .005) with the duration of PTSD symptoms. It is possible that desensitization of the hypothalamic-pituitary-adrenal axis in chronic PTSD patients counteracts the stimulatory effect of IL-1 beta on cortisol secretion.

Inflammatory cytokines regulate proliferation of cultured human osteoblasts.

We investigated the effects of various pro-inflammatory cytokines on the proliferation rate of isolated human osteoblastic cells in primary cultures. Interleukin-1 beta (IL-1 beta) and tumor necrosis factor-beta (TNF-beta) time- and dose-dependently enhanced the proliferation of human osteoblasts. Both of these cytokines also enhanced endogenous prostaglandin E2 (PGE2) formation. Exogenous PGE2 dose- and time-dependently-stimulated cell proliferation. However, the stimulatory effects of IL-1 beta and TNF-beta on osteoblast proliferation were not abolished by indomethacin, indicating a direct effect by these cytokines on the rate of proliferation. TNF-alpha stimulated proliferation at low doses, while it significantly inhibited proliferation at higher concentrations (at and above 100 pM) and with prolonged incubation times. This biphasic effect was unaffected by indomethacin. Interleukin-6, finally, did not affect the rate of proliferation. Our findings show that inflammatory cytokines may stimulate or inhibit the proliferation of isolated human osteoblasts, depending on concentration and time.

Triclosan reduces prostaglandin biosynthesis in human gingival fibroblasts challenged with interleukin-1 in vitro.

The effect of the toothpaste ingredient triclosan (2,4,4'-trichloro-2'-hydroxyldiphenyl ether) on the prostaglandins biosynthesis in human gingival fibroblasts challenged with interleukin-1beta (IL-1beta) or tumor necrosis factor alpha (TNFalpha) was studied in vitro. When gingival fibroblasts were treated simultaneously with triclosan and IL-1beta, the stimulatory effect of IL-1beta on prostaglandin E2 (PGE2) and PGI2 formation was reduced in a dose-dependent manner by triclosan. Triclosan also reduced the PGE2 formation induced by TNFalpha. Furthermore, the capacity of IL-1beta to induce release of [3H] arachidonic acid from prelabelled gingival fibroblasts was reduced in the presence of triclosan. Addition of exogenous unlabelled arachidonic acid (AA) to the cells resulted in enhanced PGE2 formation which was reduced by triclosan. The upregulation of the metabolism of AA to PGE2 induced by IL-1beta, was markedly reduced in the presence of triclosan. The study indicates that the stimulatory effect of IL-1beta on prostanoid formation (PGE2, PGI2) in human gingival fibroblasts was diminished in the presence of triclosan partly at the level of phospholipase A2 and partly at the level of cyclooxygenase. The present data that triclosan, in vitro, inhibits the production of inflammatory mediators such as prostaglandins suggests that this can be an aspect of its clinical effect on gingivitis, in addition to its antibacterial effect.

Blockade of nitric oxide formation augments adrenocorticotropin released by blood-borne interleukin-1 beta: role of vasopressin, prostaglandins, and alpha 1-adrenergic receptors

Blockade of nitric oxide (NO) formation with the arginine derivative L-N omega nitro-L-arginine-methylester (L-NAME) produces a dramatic increase in ACTH released by the iv injection of interleukin-1 beta (IL-1 beta). The present work investigated the potential role of three mechanisms in this effect: the activation of adrenergic receptors and/or the release of vasopressin (VP) or prostaglandins (PG). As previously observed, blockade of adrenergic receptors with prazosin and propranolol did not alter the stimulatory effect of IL-1 beta. We show here that this treatment did not significantly interfere with the potentiating influence of L-NAME 30 min after IL-1 injection, but blunted this effect at 60 min. Immunoneutralization of endogenous VP did not consistently decrease the ACTH response to IL-1 beta regardless of whether NO was present. Finally, as expected, blockade of PG synthesis with ibuprofen totally abolished IL-1 beta-induced ACTH secretion; in addition, it prevented the interaction between L-NAME and the pituitary response. In contrast to results obtained after the injection of IL-1 beta, neither the adrenergic antagonists nor ibuprofen significantly altered the ability of L-NAME to potentiate the stimulatory effect of VP. Collectively, these results indicate that the influence of NO on ACTH released by blood-borne IL-1 beta (an effect thought to be primarily exerted on nerve terminals in the median eminence) is not primarily mediated by endogenous VP. The inability of L-NAME to augment the stimulatory effect of the cytokine on ACTH secretion in the presence of ibuprofen suggests that PG play an obligatory role in the response of the hypothalamic-pituitary axis to systemic cytokine administration that cannot be compensated for by removing the restraining influence of NO. Finally, removal of the inhibitory effect of NO either unmasks the participation of adrenergic receptors in modulating the response of the hypothalamic-pituitary axis to IL-1 beta or stimulates catecholamine secretion, which, in turn, acts on CRF nerve terminals and/or synergizes with IL-1 beta-induced CRF release.

Blockade of nitric oxide formation augments adrenocorticotropin released by blood-borne interleukin-1 beta: role of vasopressin, prostaglandins, and alpha 1-adrenergic receptors.

Blockade of nitric oxide (NO) formation with the arginine derivative L-N omega nitro-L-arginine-methylester (L-NAME) produces a dramatic increase in ACTH released by the iv injection of interleukin-1 beta (IL-1 beta). The present work investigated the potential role of three mechanisms in this effect: the activation of adrenergic receptors and/or the release of vasopressin (VP) or prostaglandins (PG). As previously observed, blockade of adrenergic receptors with prazosin and propranolol did not alter the stimulatory effect of IL-1 beta. We show here that this treatment did not significantly interfere with the potentiating influence of L-NAME 30 min after IL-1 injection, but blunted this effect at 60 min. Immunoneutralization of endogenous VP did not consistently decrease the ACTH response to IL-1 beta regardless of whether NO was present. Finally, as expected, blockade of PG synthesis with ibuprofen totally abolished IL-1 beta-induced ACTH secretion; in addition, it prevented the interaction between L-NAME and the pituitary response. In contrast to results obtained after the injection of IL-1 beta, neither the adrenergic antagonists nor ibuprofen significantly altered the ability of L-NAME to potentiate the stimulatory effect of VP. Collectively, these results indicate that the influence of NO on ACTH released by blood-borne IL-1 beta (an effect thought to be primarily exerted on nerve terminals in the median eminence) is not primarily mediated by endogenous VP. The inability of L-NAME to augment the stimulatory effect of the cytokine on ACTH secretion in the presence of ibuprofen suggests that PG play an obligatory role in the response of the hypothalamic-pituitary axis to systemic cytokine administration that cannot be compensated for by removing the restraining influence of NO. Finally, removal of the inhibitory effect of NO either unmasks the participation of adrenergic receptors in modulating the response of the hypothalamic-pituitary axis to IL-1 beta or stimulates catecholamine secretion, which, in turn, acts on CRF nerve terminals and/or synergizes with IL-1 beta-induced CRF release.

Regulation of prostaglandin synthesis by interleukin-1 beta in cultured bovine luteal cells.

Prostaglandins produced within the CL may serve as local modulators of CL function. The present study was designed to characterize the cellular mechanisms by which the cytokine interleukin-1 beta (IL-1 beta) stimulates prostaglandin production in cultured luteal cells. Cycloheximide (CHX) and actinomycin D (Act D) did not affect basal, but completely inhibited IL-1 beta-stimulated prostaglandin F2 alpha (PGF2 alpha) production (p < 0.05). The phospholipase A2 (PLA2) inhibitor, aristolochic acid (PLA2X), and the phospholipase C (PLC) inhibitor, compound 48/80 (PLCX), suppressed IL-1 beta-stimulated (p < 0.05), but not basal, PGF2 alpha production. The addition of exogenous arachidonic acid (AA) restored the stimulatory effect of IL-1 beta in PLCX-treated, but not in PLA2X-treated, cells, suggesting that PLA2 is a key regulatory point of IL-1 beta action. Chronic exposure of the luteal cells to IL-1 beta resulted in stimulatory effects beyond that of increasing AA availability, presumably by up-regulation of prostaglandin endoperoxide (PGH) synthase. Chronic exposure of luteal cells to IL-1 beta also inhibited progesterone production, but this effect appeared to be independent of endogenous PGF2 alpha production. The ability of IL-1 beta to comprehensively stimulate luteal PGF2 alpha production while inhibiting luteal progesterone production is suggestive that IL-1 beta may facilitate regression of the CL.

Receptor-mediated stimulatory effect of IL-1 beta on hyaluronic acid and proteoglycan biosynthesis by cultured rat ovarian cells: role for heterologous cell-cell interactions.

An increasing body of information supports the possibility that intraovarian interleukin (IL)-1 may play an intermediary role in gonadotropin-triggered ovulation. To further evaluate this hypothesis, we have examined the effect of IL-1 beta on ovarian proteoglycan/glycosaminoglycan economy, an established corollary of the preovulatory cascade. Rat ovarian cells were metabolically labeled with [35S]sulfate and [3H]glucosamine for 48h in the absence or presence of IL-1 beta, with or without an IL-1 receptor antagonist (IL-1ra). At the conclusion of this treatment period, total 35S and 3H incorporation into cell-associated and extracellular proteoglycan/glycosaminoglycan species was determined. Treatment of whole ovarian dispersates with IL-1 beta (10 ng/ml) produced substantial increments in the accumulation of extracellular macromolecular material [11.5-, 2.9- and 2.6-fold for hyaluronic acid (HA), heparan sulfate (HS) and dermatan sulfate (DS) proteoglycans, respectively]. In contrast, only modest increments (< or = 1.7-fold) were noted for IL-1 beta-treated granulosa cells (GC), theca-interstitial cells (TC), or 4:1 co-cultures (GC/TC) thereof. Treatment of whole ovarian dispersates with IL-1 beta also resulted in significant (P < 0.001) increments in the cell-associated accumulation of both HA (6.0-fold increase) and DS proteoglycans (3.4-fold increase). However, the cell-associated accumulation of HS proteoglycan was not significantly affected by IL-1 beta regardless of the cellular preparation under study. The concurrent provision of IL-1ra (5 micrograms/ml) all but neutralized the IL-1 beta effect on HA biosynthesis thereby suggesting mediation by specific ovarian IL-1 receptor(s). Taken together, these observations suggest that treatment of ovarian cells with IL-1 beta results in an overall increase in macromolecular biosynthesis as well as in redistribution favoring extracellular HA and DS (but not HS) proteoglycans. Moreover, since whole ovarian dispersates proved more responsive to IL-1 than isolated cellular components thereof, the present observations suggest an obligatory requirement for heterologous cell-cell interaction without which optimal HA or proteoglycan biosynthesis may not be realized. These observations along with the demonstration of IL-1-mediated amplification of gonadotropin-triggered ovulation provide strong indirect support for the view that IL-1 may be the centerpiece of an intraovarian regulatory loop concerned with the promotion of key periovulatory events.