Interleukin-1 beta stimulates mitogen-activated protein kinase in U373 astrocytoma cells without the production of lipid second messengers

IL-1β down-regulates ADAMTS-13 mRNA expression in cells of the central nervous system

ADAMTS-13 is the Von Willebrand factor (vWF) cleaving protease, responsible for the cleavage and down-regulation of the pro-thrombotic properties of ultra large VWF multimers. It is expressed predominantly by the hepatic stellate cells of the liver, but is also found to be expressed in other tissues, including brain. Reduced ADAMTS-13 is associated with a variety of thrombotic microangiopathies. Since the cellular origin and regulation of ADAMTS-13 expression in the brain is unknown, we aimed to investigate this in four different central nervous system (CNS)-derived cell lines, SHSY-5Y (human neuroblastoma), U373 (human astroglioma), CHME-3 (human foetal microglia) and hCMEC/D3 (adult human brain endothelial cells). All cell lines expressed ADAMTS-13 mRNA constitutively with neuroblastoma cells showing the highest expression. Interleukin (IL)-1β down-regulated ADAMTS-13 mRNA expression in astroglioma cells and microglial cells whereas TNF and IL-6 treatment showed no significant differences in ADAMTS-13 mRNA expression in any cell line tested. ADAMTS-13 protein expression was reduced in a dose-dependent manner only in astroglioma cells following stimulation by IL-1β. The ability of IL-1β to significantly reduce ADAMTS-13 mRNA expression in human microglia and astroglioma cells suggests a role in the haemostasis of the local microenvironment under inflammatory conditions. This is the first report of ADAMTS-13 expression in cells of the CNS; however, its function remains to be determined.

Altered expression of a cell-cycle suppressor gene, Tob-1, in endometriotic cells by cDNA array analyses

OBJECTIVE

Interleukin (IL)-1beta, a product of activated peritoneal macrophages, is a central cytokine coordinating neovascularization and monocyte chemotaxis in endometriotic implants. To evaluate the effects of this cytokine on normal endometrial stromal cells and endometriotic stromal cells we performed cDNA expression array analyses before and after exposure to IL-1beta.

DESIGN

Nested case-control study of women with and without laparoscopic evidence of endometriosis.

SETTING

Reproductive endocrinology clinic at a university hospital.

PATIENT(S)

Endometriosis and normal endometrial biopsies from eight patients were used to prepare stromal cell cultures from which mRNA was extracted.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Commercially available expression arrays (Atlas Human cDNA Expression Array, Clontech, representing 597 individual genes) were used to screen for mRNAs whose expression was affected by 12 hours of exposure to IL-1beta (10 ng/mL). Northern blotting and subsequent quantitative densitometric evaluation was done to confirm steady-state levels of Tob-1 mRNA transcripts.

RESULT(S)

Array analyses revealed a cell-cycle regulatory gene, Tob-1, which was differentially expressed by the two cell types after incubation with IL-1beta. Tob-1 was reduced 48% in endometriotic stromal cells exposed to IL-1beta, but there was only a 16% reduction in normal endometrial stromal cells. Replicate Northern analyses (n = 4) showed that exposure to IL-1beta for 12 hours resulted in a 25% +/- 5% diminution of Tob-1 mRNA in endometriotic stromal cells. In contrast, no significant decrease (<3%) was observed in IL-1beta exposed normal endometrial stromal cells.

CONCLUSION(S)

Tob-1, a cell-cycle inhibitor gene is differentially responsive to IL-1beta in endometriotic stromal cells compared to normal endometrial stromal cells. IL-1beta down-regulated Tob-1 in endometriotic stromal cells, but had no significant effect on normal endometrial stromal cells. Our results suggest that IL-1beta promotes growth of endometriotic lesions through inhibition of Tob-1. These findings are the first to associate IL-1beta with an alteration of cell-cycle gene expression in cells derived from endometriotic implants.

Similar time-course of interleukin-1 beta production and extracellular-signal-regulated kinase (ERK) activation in permanent focal brain ischemic injury

The present study investigated the activation of extracellular-signal-regulated kinase (ERK) and the potential role of interleukin-1 beta (IL-1beta) in the brain's response to focal brain ischemia in the permanent middle cerebral artery occlusion (pMCAO) model. Phosphorylated ERK p44 and p42 were increased time-dependently and significantly 18- and 28-fold, respectively, at 24-h post-pMCAO. Similarly, IL-1beta protein levels were significantly increased with the peak at 24 h in the lesioned core of the ischemic hemisphere compared to the contralateral side. Previous studies using various stimuli have shown ERK-dependent IL-1 induction. The results from our study suggest that this relation may also exist in vivo in ischemic brain tissue. Based on the progressive nature of IL-1 induction, we hypothetized that inhibition of interleukin-converting enzyme (ICE) could provide an extended time-window for neuroprotection. Therefore, we applied N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD x fmk), an ICE blocker 3 or 6 h after pMCAO. Reductions of infarct volume, however, were not observed. Taken together with previous results, where we showed protective activity of zVAD x fmk when given immediately after pMCAO, we conclude that the time window for zVAD x fmk is less than 3 h.

Histamine H1 receptor activation stimulates mitogenesis in human astrocytoma U373 MG cells

In human astrocytoma U373 MG cells that express histamine H1 receptors (180 +/- 6 fmol/mg protein) but not H2 or H3 receptors, histamine stimulated mitogenesis as assessed by [3H]-thymidine incorporation (173 +/- 2% of basal; EC50, 2.5 +/- 0.4 microM). The effect of 100 microM histamine was fully blocked by the selective H1 antagonist mepyramine (1 microM) and was markedly reduced (93 +/- 4% inhibition) by the phospholipase C inhibitor U73122 (10 microM). The activator of protein kinase C (PKC) phorbol 12-tetradecanoyl-13-acetate (TPA, 100nM) stimulated [3H]-thymidine incorporation (270 +/- 8% of basal), and this response was not additive with that to 100 microM histamine. The incorporation of [3H]-thymidine induced by 100 microM histamine was partially reduced by the PKC inhibitor Ro 31-8220 (57 +/- 7% inhibition at 300 nM) and by the compound PD 098,059 (30 microM, 62 +/- 14% inhibition), an inhibitor of the mitogen-activated kinase (MAPK) kinases MEK1/MEK2. These results show that histamine H1 receptor activation stimulates the proliferation of human astrocytoma U373 MG cells. The action of histamine appears to be partially mediated by PKC stimulation and MAPK activation.

Autoregulation of the interleukin-1 system and cytokine-cytokine interactions in primary human astrocytoma cells

Cytokines are proposed to play important roles in brain tumor biology. Previous studies reported on interleukin-1beta (IL-1beta) production and IL-1 receptor type I (IL-1RI, signaling receptor) expression in human astrocytomas, and on IL-1beta action in astrocytoma cell lines. However, all studies that have tested the direct action of cytokines have used exclusively astrocytoma cell lines, which do not recapitulate the in situ astrocytoma. Here, we demonstrate that astrocytoma cells obtained shortly after tumor neurosurgical resection respond to the direct application of human IL-1beta with a significant upregulation of IL-1alpha, IL-1beta, IL-1RI, and tumor necrosis factor-alpha (TNF-alpha) mRNAs. IL-1 receptor antagonist (IL-1Ra, an endogenous inhibitor that blocks IL-1alpha and IL-1beta actions) mRNA was not upregulated. Application of heat-inactivated IL-1beta had no effect on any cytokine component examined, demonstrating specificity of action. On the other hand, IL-1beta application did not modulate any cytokine component in acutely resected and dissociated primitive neuroectodermal tumor cells. The data have implications for a positive autoregulatory IL-1beta feedback system and synergistic IL-1beta <=> TNF-alpha interactions, which can be involved in the growth of pilocytic astrocytomas. The results together with our previous studies also support the notion that IL-1Ra or a compound with similar cytokine inhibitory activity could be useful for brain immunotherapy of astrocytomas.

The effect of interleukin 1 beta on the biosynthesis of cholesterol, phosphatidylcholine, and sphingomyelin in fibroblasts, and on their efflux from cells to lipid-free apolipoprotein A-I

In this study we have investigated the effect of interleukin 1beta (IL-1beta) on the metabolism of cholesterol and choline-phospholipids in cultured fibroblasts, and also measured efflux of these lipids to lipid-free apo A-I as a function of IL-1beta treatment. Long-term exposure (up to 48 h) of cells to IL-1beta (1 ng.mL-1) markedly increased the rate of cholesterol esterification, as determined by the incorporation of [3H]oleic acid into cholesteryl esters. This treatment also led to a substantially increased mass of cholesteryl esters in the cells. The accumulation of cholesteryl esters in IL-1beta-treated cells could be blocked using compound 58-035 to inhibit the activity of acyl-CoA cholesterol acyl transferase. The activation of cholesterol esterification by IL-1beta was evident within a few hours after initiation of the IL-1beta treatment. Cholesterol biosynthesis was inhibited by 25% by IL-1beta (after 48 h exposure), and this eventually led to a 20% decrease in cell cholesterol mass. Treatment of cells with IL-1beta for 48 h also reduced the synthesis of sphingomyelin and caused a 30% decrease in cell sphingomyelin mass (after 48 h at 1 ng.mL-1 of IL-1beta). IL-1beta did not stimulate an acute (within a few minutes up to an hour) degradation of cell [3H]sphingomyelin. This suggests that IL-1beta did not activate an endogenous sphingomyelinase in these cells, but only affected rates of synthesis. The rate of phosphatidylcholine synthesis was barely affected, but mass was moderately reduced by a 48-h treatment of cells with IL-1beta. Finally, the efflux of cell [3H]cholesterol, [3H]sphingomyelin, and [3H]phosphatidylcholine to lipid-free apolipoprotein A-I was markedly increased from cells treated with IL-1beta for 24 and 48 h. We conclude that long-term exposure of cells to IL-1beta had marked effects on the cellular homeostasis of cholesterol and choline-containing phospholipids.