Human intestinal epithelial cells secrete interleukin-1 receptor antagonist and interleukin-8 but not interleukin-1 or interleukin-6.
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BACKGROUND: There is growing evidence that intestinal epithelial cells (IECs) are involved in the mucosal immune system. AIM: To assess the pattern of cytokines secreted by IECs and lamina propria mononuclear cells (LPMNCs). To achieve this, the expression and secretion of interleukin (IL)-1, IL-1 receptor antagonist (IL-1ra), IL-6, and IL-8 in human primary colonic and ileal IECs and LPMNCs from the same patient were studied. METHODS: IECs and LPMNCs were isolated from surgical specimens or endoscopic biopsy samples. mRNA expression was investigated by northern blot analysis. Secretion of IL-1beta, IL-6, IL-8, and IL-1ra was measured by enzyme linked immunosorbent assay. RESULTS: IL-1ra mRNA levels were higher in IECs than in LPMNCs in all probands. IL-8 mRNA was only present in low amounts in the IECs from two controls. In none of the specimens were IL-1beta and IL-6 mRNA present in IECs. Transcripts encoding IL-1beta, IL-1ra, IL-6, and IL-8 were identified in LPMNC preparations of all specimens. IECs from normal mucosa produced no detectable amounts of IL-1beta or IL-6, whereas LPMNCs did. IECs secreted some IL-8 (65 (9) pg/10(5) cells) but significantly more was generated by LPMNCs (408 (43) pg/10(5) cells, p<0.0001). However, IECs secreted more IL-1ra than did LPMNCs (120 (12) v 94 (11) pg/10(5) cells). In acute inflammation, IEC IL-1ra secretion was significantly increased. A correlation between secreted IL-1ra and the macroscopical degree of inflammation was found in Crohn's disease (r = 0.64, p<0.0001, n = 36) and ulcerative colitis (r = 0. 76, p<0.0001, n = 24). CONCLUSIONS: IECs from normal mucosa express and secrete IL-1ra and low amounts of IL-8, but no IL-1 or IL-6. In inflamed mucosa the secretion of IL-1ra by IECs is slightly increased but may be not sufficient to antagonise the greatly increased production of proinflammatory cytokines by LPMNCs and the IECs themselves. (+info)
Polarized distribution of interleukin-1 receptors and their role in regulation of serotonin transporter in placenta.
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We investigated the expression of interleukin-1 (IL-1) receptors and their involvement in the regulation of the serotonin transporter gene expression in human placenta. IL-1beta is an activator of the serotonin transporter gene expression in JAR human placental choriocarcinoma cells as demonstrated by an increase in the steady-state levels of the transporter mRNA and in serotonin transport activity. This activation is blocked by IL-1 receptor antagonist. Genistein also blocks the effect of IL-1beta, indicating involvement of tyrosine phosphorylation in the process. Treatment of JAR cells with IL-1beta activates mitogen-activated protein kinases and nuclear factor-kappaB. The nuclear factor-kappaB that is responsive to IL-1beta in these cells is the p65 homodimer. Northern blot analysis and reverse transcription-polymerase chain reaction revealed that JAR cells and human placenta express type I and type II IL-1 receptors. The binding sites for (125)I-IL-1beta are localized predominantly in the maternal-facing brush border membrane of the syncytiotrophoblast. These results show that IL-1 in the maternal circulation is likely to play a critical role in the regulation of the serotonin transporter gene expression in the placenta. (+info)
Induction of an angiogenic phenotype in endometriotic stromal cell cultures by interleukin-1beta.
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Activated peritoneal macrophages are associated with endometriosis and may play a central role in its aetiology by releasing interleukin-1beta (IL-1beta) in response to refluxed endometrium. Pari passu with the establishment of endometriotic implants is the development of a vascular supply. In this study we investigated the angiogenic properties of two endometrial proteins, vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6), and assessed their production in response to IL-1beta stimulation in human stromal cells isolated from normal endometrium (NE) and endometriotic lesions (EI). Proliferation of bovine brain capillary endothelial cells (BBCE) with a [(3)H]-thymidine incorporation assay was observed when VEGF (2.1 +/- 0.2-fold; P < 0.05) or VEGF and IL-6 (1.8 +/- 0.1-fold; P < 0.05) were added in vitro, relative to saline-treated control cultures. Northern blot analysis showed induction of VEGF mRNA (2.6-fold; P < 0.05) and IL-6 mRNA (6.3-fold; P < 0.05) transcripts in EI cells, but not NE cells, exposed to IL-1beta. A similar induction was seen with VEGF and IL-6 protein secretion in the responsive EI cells. Reverse transcription-polymerase chain reaction (RT-PCR) for the IL-1 receptor type I (IL-1 RI) indicated that the differential effects of IL-1beta on NE and EI cells was associated with 2.4 +/- 0.1-fold more receptor mRNA in EI versus NE cells. We propose that the ability of IL-1beta to activate an angiogenic phenotype in EI stromal cells but not in NE cells, is mediated by the IL-1 RI. (+info)
Deficiency of the stress kinase p38alpha results in embryonic lethality: characterization of the kinase dependence of stress responses of enzyme-deficient embryonic stem cells.
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The mitogen-activated protein (MAP) kinase p38 is a key component of stress response pathways and the target of cytokine-suppressing antiinflammatory drugs (CSAIDs). A genetic approach was employed to inactivate the gene encoding one p38 isoform, p38alpha. Mice null for the p38alpha allele die during embryonic development. p38alpha(1/)- embryonic stem (ES) cells grown in the presence of high neomycin concentrations demonstrated conversion of the wild-type allele to a targeted allele. p38alpha(-/)- ES cells lacked p38alpha protein and failed to activate MAP kinase-activated protein (MAPKAP) kinase 2 in response to chemical stress inducers. In contrast, p38alpha(1/+) ES cells and primary embryonic fibroblasts responded to stress stimuli and phosphorylated p38alpha, and activated MAPKAP kinase 2. After in vitro differentiation, both wild-type and p38alpha(-/)- ES cells yielded cells that expressed the interleukin 1 receptor (IL-1R). p38alpha(1/+) but not p38alpha(-/)- IL-1R-positive cells responded to IL-1 activation to produce IL-6. Comparison of chemical-induced apoptosis processes revealed no significant difference between the p38alpha(1/+) and p38alpha(-/)- ES cells. Therefore, these studies demonstrate that p38alpha is a major upstream activator of MAPKAP kinase 2 and a key component of the IL-1 signaling pathway. However, p38alpha does not serve an indispensable role in apoptosis. (+info)
Beta-amyloid stimulation of inducible nitric-oxide synthase in astrocytes is interleukin-1beta- and tumor necrosis factor-alpha (TNFalpha)-dependent, and involves a TNFalpha receptor-associated factor- and NFkappaB-inducing kinase-dependent signaling mechanism.
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In Alzheimer's disease, beta-amyloid (Abeta) plaques are surrounded by activated astrocytes and microglia. A growing body of evidence suggests that these activated glia contribute to neurotoxicity through the induction of inflammatory cytokines such as interleukin (IL)-1beta and tumor necrosis factor-alpha (TNFalpha) and the production of neurotoxic free radicals, mediated in part by the expression of inducible nitric-oxide synthase (iNOS). Here, we address the possibility that Abeta-stimulated iNOS expression might result from an initial induction of IL-1beta and TNFalpha. We find that in Abeta-stimulated astrocyte cultures, IL-1beta and TNFalpha production occur before iNOS production, new protein synthesis is required for increased iNOS mRNA levels, and the IL-1 receptor antagonist IL-1ra can inhibit nitrite accumulation. Likewise, dominant-negative mutants of tumor necrosis factor-alpha receptor-associated factor (TRAF) 6, TRAF2, and NFkappaB-inducing kinase (NIK), intracellular proteins involved in IL-1 and TNFalpha receptor signaling cascades, inhibit Abeta-stimulated iNOS promoter activity. Our data suggest that Abeta stimulation of astrocyte iNOS is mediated in part by IL-1beta and TNFalpha, and involves a TRAF6-, TRAF2-, and NIK-dependent signaling mechanism. (+info)
T1/ST2-deficient mice demonstrate the importance of T1/ST2 in developing primary T helper cell type 2 responses.
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We have generated mice with a deficiency in T1/ST2 expression to clarify the roles of T1/ST2 in T helper cell type 2 (Th2) responses. Using immunological challenges normally characterized by a Th2-like response, we have compared the responses of T1/ST2-deficient mice with those generated by wild-type mice. Using a primary pulmonary granuloma model, induced with Schistosoma mansoni eggs, we demonstrate that granuloma formation, characterized by eosinophil infiltration, is abrogated in T1/ST2-deficient mice. Furthermore, we clearly demonstrate that in the absence of T1/ST2 expression, the levels of Th2 cytokine production are severely impaired after immunization. Thus, in a secondary pulmonary granuloma model, draining lymph node cells from the T1/ST2-deficient animals produced significantly reduced levels of IL-4 and IL-5, despite developing granulomas of a magnitude similar to those of wild-type mice and comparable antigen-specific immunoglobulin isotype production. These data clearly demonstrate that T1/ST2 expression plays a role in the development of Th2-like cytokine responses and indicate that effector functions are inhibited in its absence. (+info)
Abnormal IL-1 receptor antagonist production in patients with polymyositis and dermatomyositis.
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OBJECTIVE: To examine the relationship between serum levels of interleukin-1 receptor antagonist (IL-1Ra) and its gene expression in peripheral blood mononuclear cells (PBMC) from patients with polymyositis and dermatomyositis (PM/DM). METHODS: IL-1Ra levels in sera from patients and supernatants of unstimulated monocyte cultures were measured by enzyme-linked immunosorbent assay. Expression of IL-1Ra mRNA was analyzed by Northern blotting, and an 86-base pair variable repeat polymorphism in intron 2 of the IL-1Ra gene was determined by polymerase chain reaction. RESULTS: Serum IL-1Ra was significantly elevated in 27 patients with active-stage PM/DM when compared with levels in 16 patients with inactive-stage PM/DM and 19 normal controls. Serum concentrations of IL-1Ra were correlated with PM/DM disease activity. IL-1Ra mRNA was detected in freshly isolated PBMC from patients with active-stage PM/DM, but not in controls. Moreover, IL-1Ra concentrations were increased significantly in unstimulated monocytes from patients with active-stage PM/DM compared with monocytes from normal controls. However, there were no significant differences in IL-1Ra allele frequencies between patients and normal controls. CONCLUSION: Elevation of both IL-1Ra mRNA and protein in sera of patients with active-stage PM/DM suggest that higher levels of serum IL-1Ra may reflect increased IL-1Ra production in myositis, and that IL-1Ra may regulate IL-1-mediated muscle fiber damage in PM/DM. (+info)
Cytokine-stimulated, but not HIV-infected, human monocyte-derived macrophages produce neurotoxic levels of l -cysteine.
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Approximately one-quarter of individuals with AIDS develop neuropathological symptoms that are attributable to infection of the brain with HIV. The cognitive manifestations have been termed HIV-associated dementia. The mechanisms underlying HIV-associated neuronal injury are incompletely understood, but various studies have confirmed the release of neurotoxins by macrophages/microglia infected with HIV-1 or stimulated by viral proteins, including the envelope glycoprotein gp120. In the present study, we investigated the possibility that l -cysteine, a neurotoxin acting at the N-methyl-d -aspartate subtype of glutamate receptor, could contribute to HIV-associated neuronal injury. Picomolar concentrations of gp120 were found to stimulate cysteine release from human monocyte-derived macrophages (hMDM) in amounts sufficient to injure cultured rat cerebrocortical neurons. TNF-alpha and IL-1beta, known to be increased in HIV-encephalitic brains, as well as a cellular product of cytokine stimulation, ceramide, were also shown to induce release of cysteine from hMDM in a dose-dependent manner. A TNF-alpha-neutralizing Ab and an IL-1betaR antagonist partially blocked gp120-induced cysteine release, suggesting that these cytokines may mediate the actions of gp120. Interestingly, hMDM infected with HIV-1 produced significantly less cysteine than uninfected cells following stimulation with TNF-alpha. Our findings imply that cysteine may play a role in the pathogenesis of neuronal injury in HIV-associated dementia due to its release from immune-activated macrophages but not virus-infected macrophages. Such uninfected cells comprise the vast majority of mononuclear phagocytes (macrophages and microglia) found in HIV-encephalitic brains. (+info)