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Neuroprotection by interleukin-6 is mediated by signal transducer and activator of transcription 3 and antioxidative signaling in ischemic stroke.

ABSTRACT: Interleukin-6 (IL-6) has been shown to have a neuroprotective effect in brain ischemic injury. However, its molecular mechanisms are still poorly understood. In this study, we investigated the neuroprotective role of the IL-6 receptor (IL-6R) by IL-6 in the reactive oxygen species defense system after transient focal cerebral ischemia (tFCI).IL-6 was injected in mice before and after middle cerebral artery occlusion. Coimmunoprecipitation assays were performed for analysis of an IL-6R association after tFCI. Primary mouse cerebral cortical neurons were transfected with small interfering RNA probes targeted to IL-6R? or gp130 and were used for chromatin-immunoprecipitation assay, luciferase promoter assay, and cell viability assay. Reduction in infarct volumes by IL-6 was measured after tFCI.IL-6R was disrupted through a disassembly between IL-6R? and gp130 associated by protein oxidation after reperfusion after tFCI. This suppressed phosphorylation of signal transducer and activator of transcription 3 (STAT3) and finally induced neuronal cell death through a decrease in manganese-superoxide dismutase. However, IL-6 injections prevented disruption of IL-6R against reperfusion after tFCI, consequently restoring activity of STAT3 through recovery of the binding of STAT3 to gp130. Moreover, IL-6 injections restored the transcriptional activity of the manganese-superoxide dismutase promoter through recovery of the recruitment of STAT3 to the manganese-superoxide dismutase promoter and reduced infarct volume after tFCI.This study demonstrates that IL-6 has a neuroprotective effect against cerebral ischemic injury through IL-6R-mediated STAT3 activation and manganese-superoxide dismutase expression.

SUBMITTER: Jung JE

PROVIDER: S-EPMC3395465 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature

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Neuroprotection by interleukin-6 is mediated by signal transducer and activator of transcription 3 and antioxidative signaling in ischemic stroke.

Jung Joo Eun JE Kim Gab Seok GS Chan Pak H PH

Stroke 20110922 12

<h4>Background and purpose</h4>Interleukin-6 (IL-6) has been shown to have a neuroprotective effect in brain ischemic injury. However, its molecular mechanisms are still poorly understood. In this study, we investigated the neuroprotective role of the IL-6 receptor (IL-6R) by IL-6 in the reactive oxygen species defense system after transient focal cerebral ischemia (tFCI).<h4>Methods</h4>IL-6 was injected in mice before and after middle cerebral artery occlusion. Coimmunoprecipitation assays wer ...[more]

PMID: 21940958

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Project description:Study questionAre STAT3 signaling molecules differentially expressed in endometriosis?Summary answerLevels of phospho-STAT3 and HIF1A, its downstream signaling molecule, are significantly higher in eutopic endometrium from women with endometriosis when compared with women without the disease.What is known alreadyEndometriosis is an estrogen-dependent inflammatory condition. Interleukin 6 (IL-6) is an inflammatory survival cytokine known to induce prolonged activation of STAT3 via association with the IL-6 receptor.Study design, size, durationCross-sectional measurements of STAT3 and HIF1A protein levels in eutopic endometrium from women with endometriosis versus those without.Participants/materials, setting, methodsLevels of phospho-STAT3 (pSTAT3) and HIF1A were examined in the endometrium of patients with and without endometriosis as well as in a non-human primate animal model using western blot and immunohistochemical analysis.Main results and the role of chanceLevels of pSTAT3 were significantly higher in the eutopic endometrium from women with endometriosis when compared with women without the disease in both the proliferative and secretory phases. HIF1A is known to be stabilized by STAT3 and IL-6. Our immunohistochemistry results show abundant HIF1A expression within the eutopic endometrial epithelial cells of women with endometriosis. Furthermore, pSTAT3 and HIF1A proteins are co-localized in endometriosis. This aberrant activation of pSTAT3 and HIF1A is confirmed by sequential analysis of eutopic endometrium using a baboon animal model of induced endometriosis. Lastly, we confirmed this IL-6 induction of both STAT3 phosphorylation and HIF1A mRNA expression in Ishikawa human endometrial adenocarcinoma cell line.Limitations, reasons for cautionIshikawa cancer cell line was used to study a benign disease. The peritoneal fluid contains various inflammatory cytokines in addition to IL-6 and so it is possible that other cytokines may affect the activity and expression of STAT3 signaling molecules.Wider implications of the findingsOur results imply that aberrant activation of STAT3 signaling plays an important role in the pathogenesis of endometriosis. Our findings could progress in our understanding of the etiology and pathophysiology of endometriosis and potential therapeutic interventions by targeted pharmacological.Study funding/competing interestsThis work was supported by NIH R01 HD067721 (to S.L.Y and B.A.L) and NIH R01 HD057873 and American Cancer Society Research Grant RSG-12-084-01-TBG (to J.-W.J.). There are no conflicts of interest.

Project description:BackgroundMesenchymal stem cells (MSCs) transplantation has been proven to have therapeutic potential for acute liver failure (ALF). However, the mechanism remains controversial. Recently, modulation of inflammation by MSCs has been regarded as a crucial mechanism. The aim of the present study was to explore the soluble cytokines secreted by MSCs and their therapeutic effects in ALF.MethodsMSCs isolated from Sprague-Dawley rats were identified by fluorescence-activated cell sorting analysis. Conditioned medium derived from MSCs (MSCs-CM) was collected and analyzed by a cytokine microarray. MSCs and MSCs-CM were transplanted into rats with D-galactosamine-induced ALF. Liver function, survival rate, histology, and inflammatory factors were determined. Exogenous recombinant rat interleukin (IL)-10, anti-rat IL-10 antibody, and AG490 (signal transducer and activator of transcription 3 [STAT3] signaling pathway inhibitor) were administered to explore the therapeutic mechanism of MSCs-CM. Statistical analysis was performed with SPSS version 19.0, and all data were analyzed by the independent-sample t-test.ResultsThere are statistical differences of the survival curve between ALF+MSCs group and ALF+Dulbecco's modified Eagle's medium (DMEM) group, as well as ALF+MSCs-CM group and ALF+DMEM group (all P < 0.05). Serum alanine aminotransferase (ALT) level in the ALF+MSCs and ALF+MSCs-CM groups was lower than that in the ALF+DMEM group (865.53±52.80 vs. 1709.75±372.12 U/L and 964.72±414.59 vs. 1709.75±372.12 U/L, respectively, all P < 0.05); meanwhile, serum aspartate aminotransferase (AST) level in the ALF+MSCs and ALF+MSCs-CM groups was lower than that in the ALF+DMEM group (2440.83±511.94 vs. 4234.35±807.30 U/L and 2739.83±587.33 vs. 4234.35±807.30 U/L, respectively, all P < 0.05). Furthermore, MSCs or MSCs-CM treatment significantly reduced serum interferon-γ (IFN-γ), IL-1β, IL-6 levels and increased serum IL-10 level compared with DMEM (all P < 0.05). Proteome profile analysis of MSCs-CM indicated the presence of anti-inflammatory factors and IL-10 was the most distinct. Blocking of IL-10 confirmed the therapeutic significance of this cytokine. Phosphorylated STAT3 was upregulated after IL-10 infusion and inhibition of STAT3 by AG490 reversed the therapeutic effect of IL-10.ConclusionsThe factors released by MSCs, especially IL-10, have the potential for therapeutic recovery of ALF, and the STAT3 signaling pathway may mediate the anti-inflammatory effect of IL-10.

Project description:UNLABELLED:Alcoholic and nonalcoholic steatohepatitis are characterized by fatty liver plus inflammation. It is generally believed that steatosis promotes inflammation, whereas inflammation in turn aggregates steatosis. Thus, we hypothesized the deletion of interleukin (IL)-10, a key anti-inflammatory cytokine, exacerbates liver inflammation, steatosis, and hepatocellular damage in alcoholic and nonalcoholic fatty liver disease models that were achieved via feeding mice with a liquid diet containing 5% ethanol for 4 weeks or a high-fat diet (HFD) for 12 weeks, respectively. IL-10 knockout (IL-10(-/-)) mice and several other strains of genetically modified mice were generated and used. Compared with wild-type mice, IL-10(-/-) mice had greater liver inflammatory response with higher levels of IL-6 and hepatic signal transducer and activator of transcription 3 (STAT3) activation, but less steatosis and hepatocellular damage after alcohol or HFD feeding. An additional deletion of IL-6 or hepatic STAT3 restored steatosis and hepatocellular damage but further enhanced liver inflammatory response in IL-10(-/-) mice. In addition, the hepatic expression of sterol regulatory element-binding protein 1 and key downstream lipogenic proteins and enzymes in fatty acid synthesis were down-regulated in IL-10(-/-) mice. Conversely, IL-10(-/-) mice displayed enhanced levels of phosphorylated adenosine monophosphate-activated protein kinase and its downstream targets including phosphorylated acetyl-coenzyme A carboxylase and carnitine palmitoyltransferase 1 in the liver. Such dysregulations were corrected in IL-10(-/-) IL-6(-/-) or IL-10(-/-) STAT3(Hep-/-) double knockout mice. CONCLUSION:IL-10(-/-) mice are prone to liver inflammatory response but are resistant to steatosis and hepatocellular damage induced by ethanol or HFD feeding. Resistance to steatosis in these mice is attributable to elevation of inflammation-associated hepatic IL-6/STAT3 activation that subsequently down-regulates lipogenic genes but up-regulates fatty acid oxidation-associated genes in the liver.

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Neuroprotection by interleukin-6 is mediated by signal transducer and activator of transcription 3 and antioxidative signaling in ischemic stroke.

Publications

Neuroprotection by interleukin-6 is mediated by signal transducer and activator of transcription 3 and antioxidative signaling in ischemic stroke.

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