Increased Expression Of Interleukin Research Articles

Impaired cognition and cerebral glucose regulation are associated with astrocyte activation in the parenchyma of metabolically stressed APPswe/PS1dE9 mice

Although metabolic syndrome was suggested to be a risk factor for Alzheimer's disease (AD), the role of metabolic stress in the initiation of AD pathology remains unclear. In this study, metabolic stress was induced by a high-fat diet and low-dose injection of streptozotocin (HFSTZ) before the appearance of senile plaques in APP/PS1 transgenic mice. We found that, HFSTZ treatment exacerbated amyloid beta burden and astrocyte activation in the vicinity of plaques. Moreover, we observed an upregulation of astrocytic S100B expression in the brain parenchyma of HFSTZ-treated APP/PS1 mice concurrent with increased interleukin-6 expression in cerebral microvascular cells. To determine the impact of HFSTZ treatment on brain function, we performed [18F]fludeoxyglucose-positron emission tomography and analyzed nesting behavior. HFSTZ treatment impaired nest construction and cerebral glucose metabolism in several brain regions of APP/PS1 mice during the early stage of AD. These results suggest that HFSTZ-induced peripheral metabolic stress may contribute to vascular inflammation and astrocyte reactivity in the parenchyma and may impair activity of daily living skill and cerebral glucose metabolism in APP/PS1 mice.

Increased CD40+ Fibrocytes in Patients With Idiopathic Orbital Inflammation.

To investigate the phenotypic and functional characteristics of peripheral and tissue-infiltrating stem cells called fibrocytes in patients with idiopathic orbital inflammation (IOI). Seven patients with IOI were studied. In the 3 patients requiring orbital biopsy, fibrocytes were identified in orbital tissue from patients with IOI compared with healthy controls using immunohistochemistry. Fibrocytes from the peripheral blood of all 7 patients and controls were quantified and phenotyped by flow cytometry and immunofluorescence for expression of CD34, alpha smooth muscle actin, CD40, and collagen 1. Quantitation of CD40-mediated interleukin-6 (IL-6) production was measured using enzyme-linked immunosorbent assay. Orbital biopsy specimens from patients with IOI demonstrate tissue infiltration by fibrocytes (n = 3). Fibrocytes are present in the peripheral blood of IOI patients (n = 7) but are scarce in healthy donors (n = 19). Fibrocytes from IOI patients express substantial levels of CD40, and ligation of CD40 increases IL-6 expression. Fibrocytes are present in the peripheral blood and orbital tissues of patients with IOI and constitutively express CD40 and express IL-6 in response to ligation. This site-specific predilection of CD34(+) fibrocytes to sites of orbital inflammation and fibrosis may suggest a role in IOI. Moreover, CD40-mediated activation cytokine production may contribute to the proinflammatory and profibrotic features of IOI and may provide a mechanism for future targeted therapy.

The novel inhibitor BRM270 downregulates tumorigenesis by suppression of NF-κB signaling cascade in MDR-induced stem like cancer-initiating cells.

The nuclear factor κB (NF-κB) and interleukin-6 (IL-6) contribute to multidrug resistance (MDR) in tumor chemotherapy. The essential phenomenon of oncogenic activation of NF-κB in cancer-initiating cells showing MDR resulting from increased IL-6 expression is still unclear. Cancer stem cells (CSCs) have been the objective of intensive study. The aim of this study was to investigate the selective and potential efficacy of BRM270 against stem-like cancer-initiating cells (SLCICs) via the molecular mechanisms of its anticancer effects. Co-regulation of NF-κB and Cdk6 might be new arena to mitigate tumorigenesis. In the present study phyto-drug based approach provides a new avenue in understanding the amelioration and regulatory mechanisms in CSCs. In the present study, an in vivo tumor metastasis model of osteosarcoma was established by injecting Cal72 and SaOS-2 SLCICs into the right lower flank of nude mice. Later the development of tumor was analyzed by LICOR Biosciences (Pearl image analyzer). Significant suppression of activation of NF-κB and LPS-induced gene expression and apoptosis by BRM270 was confirmed by FACS, western blotting and qPCR. Further, both p65 and Cdk6 were significantly (P<0.05) overexpressed in BRM270 non-treated Cal72 SLCICs compared to treated group. BRM270 directly dephosphorylated RelA and selectively inhibited NF-κB transcriptional activity, resulting in decreased expression of interleukin-6, a cytokine implicated in cancer metastasis. BRM270-mediated cell shrinkage, pyknosis, karyorrhexis and programmed cell death (PCD) were observed by Hoechst 33342 staining while flow cytometry analysis showed significant (P<0.05) decrease in cell population from G0-G1 phases. These findings suggest that activation of the oncogenic Cdk6-NF-κB pathway, resulting from increased IL-6 expression, plays a central role in CD133 expressing SLCICs augmented MDR and neoplasia. This study proposes targeting of NF-κB, and Cdk6 with IL-6 as potential targets for PCD and treatment of chemotherapeutic resistance of CSCs to design novel therapies for their elimination.

Anticancer drug bortezomib increases interleukin-8 expression in human monocytes

Bortezomib (BZ) is the first clinically approved proteasome inhibitor that has shown remarkable anticancer activity in patients with hematological malignancies. However, many patients relapse and develop resistance; yet, the molecular mechanisms of BZ resistance are not fully understood. We have recently shown that in solid tumors, BZ unexpectedly increases expression of the pro-inflammatory and pro-angiogenic chemokine interleukin-8 (IL-8), while it inhibits expression of other NFκB-regulated genes. Since monocytes and macrophages are major producers of IL-8, the goal of this study was to test the hypothesis that BZ increases the IL-8 expression in human monocytes and macrophages. Here, we show that BZ dramatically increases the IL-8 expression in lipopolysaccharide (LPS)-stimulated U937 macrophages as well as in unstimulated U937 monocytes and peripheral blood mononuclear cells, while it inhibits expression of IL-6, IL-1 and tumor necrosis factor-α. In addition, our results show that the underlying mechanisms involve p38 mitogen-activated protein kinase, which is required for the BZ-induced IL-8 expression. Together, these data suggest that the BZ-increased IL-8 expression in monocytes and macrophages may represent one of the mechanisms responsible for the BZ resistance and indicate that targeting the p38-mediated IL-8 expression could enhance the BZ effectiveness in cancer treatment.

Abstract W P403: Interleukin-6 Is Regulated By Let7 In Ischemic Stroke

Background: Interleukin-6 (IL-6) is increased in ischemic stroke and associated with increased mortality and morbidity. microRNA are important regulators of inflammation and may be central to IL-6 expression in stroke. In this study we evaluated the regulation of IL-6 by microRNA in ischemic stroke. Methods: IL-6 and microRNA were evaluated in circulating leukocytes of patients with ischemic stroke (n=106) and vascular risk factor controls (n=106). In a culture model of monocyte activation following stroke, the effect of let7 transfection on IL-6 expression was evaluated. Results: In patients with ischemic stroke let7 microRNA was found to be decreased compared to risk factor controls (corrected p&lt;0.01, fold change&lt;1.4). This decrease correlated with an increase in IL-6 gene expression. In culture, stimulated monocytes expressed increased IL-6. Transfection of let7 mimic decreased IL-6 expression, whereas let7 inhibitor increased IL-6 expression. This effect was dependent on toll-like receptor 4 (TLR4) activation, and could be abolished with the TLR4 inhibitor Tak242. Conclusions: Il-6 expression is regulated by microRNA let7 in ischemic stroke and thus may be an important determinant of post-ischemic cerebral inflammation.

Therapeutic effects of intravenous administration of bone marrow stromal cells on sevoflurane-induced neuronal apoptosis and neuroinflammation in neonatal rats.

BackgroundSevoflurane exposure during the early postnatal period causes neuroinflammation and neuronal apoptosis in rodents. Bone marrow stromal cells (BMSCs) have been shown to protect and repair the damaged central nervous system, for example in ischemic stroke models. In this study, we investigated whether intravenous administration of BMSCs ameliorated neurodegeneration, induced by sevoflurane exposure, in neonatal rats.MethodsSprague-Dawley rat pups (postnatal day 7) were exposed to 2% sevoflurane for 6 h (vehicle group, n = 7). BMSCs were administered 30 min after induction of sevoflurane anesthesia (BMSCs group, n = 7). The pups were exposed to carrier gas only, as a negative control (mock anesthesia group, n = 4). We assessed the therapeutic effects of BMSC treatment by measuring expression of the pro-inflammatory cytokine interleukin-6 (IL-6), and levels of cleaved caspase-3, in brain tissues immediately following sevoflurane anesthesia.ResultsAnalysis of the cleaved caspase-3 bands revealed that levels of activated caspase-3 were elevated in the vehicle group compared with the mock anesthesia group, indicating that a single exposure to sevoflurane at subclinical concentrations can precipitate neuronal apoptosis. BMSC treatment did not suppress apoptosis induced by sevoflurane exposure (compared with the vehicle group). The vehicle group had higher proinflammatory cytokine IL-6 protein levels compared with the mock anesthesia group, indicating that sevoflurane exposure induces IL-6 expression. BMSC treatment suppressed sevoflurane-induced increases in IL-6 expression, indicating that these cells can inhibit the neuroinflammation induced by sevoflurane exposure (vehicle group vs. BMSC group).ConclusionsIntravenous administration of BMSCs reduces neuroinflammation, but does not attenuate apoptosis induced by sevoflurane exposure.

Peptidoglycan Induces the Production of Interleukin-8 via Calcium Signaling in Human Gingival Epithelium.

The etiology of periodontal disease is multifactorial. Exogenous stimuli such as bacterial pathogens can interact with toll-like receptors to activate intracellular calcium signaling in gingival epithelium and other tissues. The triggering of calcium signaling induces the secretion of pro-inflammatory cytokines such as interleukin-8 as part of the inflammatory response; however, the exact mechanism of calcium signaling induced by bacterial toxins when gingival epithelial cells are exposed to pathogens is unclear. Here, we investigate calcium signaling induced by bacteria and expression of inflammatory cytokines in human gingival epithelial cells. We found that peptidoglycan, a constituent of gram-positive bacteria and an agonist of toll-like receptor 2, increases intracellular calcium in a concentration-dependent manner. Peptidoglycan-induced calcium signaling was abolished by treatment with blockers of phospholipase C (U73122), inositol 1,4,5-trisphosphate receptors, indicating the release of calcium from intracellular calcium stores. Peptidoglycan-mediated interleukin-8 expression was blocked by U73122 and 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis (acetoxymethyl ester). Moreover, interleukin-8 expression was induced by thapsigargin, a selective inhibitor of the sarco/endoplasmic reticulum calcium ATPase, when thapsigargin was treated alone or co-treated with peptidoglycan. These results suggest that the gram-positive bacterial toxin peptidoglycan induces calcium signaling via the phospholipase C/inositol 1,4,5-trisphosphate pathway, and that increased interleukin-8 expression is mediated by intracellular calcium levels in human gingival epithelial cells.

Indoxyl Sulfate Induces IL-6 Expression in Vascular Endothelial and Smooth Muscle Cells through OAT3-Mediated Uptake and Activation of AhR/NF-κB Pathway

Background/Aims: Interleukin-6 (IL-6) is one of the inflammation biomarkers with highest predictive value for outcome in chronic kidney disease (CKD) patients. The present study aimed to determine the effects of indoxyl sulfate (IS) on IL-6 expression in vascular cells. Methods: IS was administered to normo- and hypertensive rats. Human umbilical vein endothelial cells (HUVECs) and human aortic smooth muscle cells (HASMCs) were incubated with or without IS. Results: Immunohistochemistry revealed that IS-administered rats showed increased expression of IL-6 in the aortic tissues. IS increased IL-6 expression in HUVECs and HASMCs in a time- and dose-dependent manner. Knockdown of organic anion transporter 3 (OAT3) using small interfering RNA (siRNA) inhibited IS-induced expression of IL-6 in HUVECs and HASMCs. IS induced activation of aryl hydrocarbon receptor (AhR) and nuclear factor-κB (NF-κB) subunit p65 in HUVECs and HASMCs. Both AhR siRNA and p65 siRNA inhibited IS-induced expression of IL-6. AhR siRNA inhibited IS-induced phosphorylation and nuclear translocation of p65 without change in total p65 level. However, p65 siRNA did not inhibit IS-induced nuclear translocation of AhR. Thus, AhR is responsible for IS-induced p65 signaling transduction. Conclusion: IS induces IL-6 expression in vascular endothelial and smooth muscle cells through OAT3/AhR/NF-κB pathway.

Adipocyte Lipolysis-stimulated Interleukin-6 Production Requires Sphingosine Kinase 1 Activity

Adipocyte lipolysis can increase the production of inflammatory cytokines such as interleukin-6 (IL-6) that promote insulin resistance. However, the mechanisms that link lipolysis with inflammation remain elusive. Acute activation of β3-adrenergic receptors (ADRB3) triggers lipolysis and up-regulates production of IL-6 in adipocytes, and both of these effects are blocked by pharmacological inhibition of hormone-sensitive lipase. We report that stimulation of ADRB3 induces expression of sphingosine kinase 1 (SphK1) and increases sphingosine 1-phosphate production in adipocytes in a manner that also depends on hormone-sensitive lipase activity. Mechanistically, we found that adipose lipolysis-induced SphK1 up-regulation is mediated by the c-Jun N-terminal kinase (JNK)/activating protein-1 signaling pathway. Inhibition of SphK1 by sphingosine kinase inhibitor 2 diminished the ADRB3-induced IL-6 production both in vitro and in vivo. Induction of IL-6 by ADRB3 activation was suppressed by siRNA knockdown of Sphk1 in cultured adipocytes and was severely attenuated in Sphk1 null mice. Conversely, ectopic expression of SphK1 increased IL-6 expression in adipocytes. Collectively, these data demonstrate that SphK1 is a critical mediator in lipolysis-triggered inflammation in adipocytes.

Human cytomegalovirus-encoded pUL7 is a novel CEACAM1-like molecule responsible for promotion of angiogenesis.

ABSTRACTPersistent human cytomegalovirus (HCMV) infection has been linked to several diseases, including atherosclerosis, transplant vascular sclerosis (TVS), restenosis, and glioblastoma. We have previously shown that factors secreted from HCMV-infected cells induce angiogenesis and that this process is due, at least in part, to increased secretion of interleukin-6 (IL-6). In order to identify the HCMV gene(s) responsible for angiogenesis promotion, we constructed a large panel of replication-competent HCMV recombinants. One HCMV recombinant deleted for UL1 to UL10 was unable to induce secretion of factors necessary for angiogenesis. Fine mapping using additional HCMV recombinants identified UL7 as a viral gene required for production of angiogenic factors from HCMV-infected cells. Transient expression of pUL7 induced phosphorylation of STAT3 and ERK1/2 MAP kinases and production of proangiogenic factors, including IL-6. Addition of recombinant pUL7 to cells was sufficient for angiogenesis and was again associated with increased IL-6 expression. Analysis of the UL7 structure revealed a conserved domain similar to the immunoglobulin superfamily domain and related to the N-terminal V-like domain of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1). Our report therefore identifies UL7 as a novel HCMV-encoded molecule that is both structurally and functionally related to cellular CEACAM1, a proangiogenic factor highly expressed during vasculogenesis.

SRC-mediated EGF receptor activation regulates ozone-induced interleukin 8 expression in human bronchial epithelial cells.

Background:Human exposure to ozone (O3) results in pulmonary function decrements and airway inflammation. The mechanisms underlying these adverse effects remain unclear. Epidermal growth factor receptor (EGFR) plays an important role in the pathogenesis of lung inflammation.ObjectiveWe examined the role of EGFR activation in O3-induced expression of the chemokine interleukin 8 (IL-8) in human bronchial epithelial cells (HBEC).MethodsWe detected phosphorylated EGFR using immunoblotting. EGFR dimerization was examined through cross-linking reaction and immunoblotting, and levels of IL-8 protein were measured using ELISA.ResultsExposure to O3 (0.25–1.0 ppm) induced rapid and marked increase in EGFR phosphorylation at the autophosphorylation site Y1068 and the transphosphorylation site Y845, implicating the involvement of Src kinase. Further investigation showed that O3 stimulation induced phosphorylation of Src at Y416, indicative of Src activation. Pharmacological inhibition of Src kinase activity abrogated O3-induced EGFR phosphorylation at tyrosines 1068 and 845. Moreover, pretreatment of BEAS-2B cells with inhibitor of either EGFR or Src kinase activities significantly blocked O3-induced IL-8 expression.ConclusionConclusion: O3 exposure increased IL-8 expression through Src-mediated EGFR transactivation in HBEC.Citation>Wu W, Wages PA, Devlin RB, Diaz-Sanchez D, Peden DB, Samet JM. 2015. Src-mediated EGF receptor activation regulates ozone-induced interleukin 8 expression in human bronchial epithelial cells. Environ Health Perspect 123:231–236; http://dx.doi.org/10.1289/ehp.1307379

Abstract 157: Lapatinib induces IL-6 expression via MAPK pathway in triple-negative breast cancer cells

Abstract Lapatinib, the dual epidermal growth factor receptor (EGFR) and HER2 tyrosine kinase inhibitor (TKI), have been tested in triple negative breast cancer (TNBC) patients in several clinical studies. However, limited clinic benefit was observed, and the metastatic ability of TNBC cells was even unexpectedly enhanced by these anti-cancer drugs in our previous studies. In this study, we found that induction of interleukin-6 (IL-6) expression was induced in lapatinib-treated cells to contribute to their increased ability of migration. Treatment of cells with the IL-6 antibody abolished the lapatinib-induced cell migration. In response to lapatinib treatment, Raf-1, Mitogen-activated protein kinases (MAPK), c-Jun N-terminal kinases (JNK), p38 mitogen activated protein kinase (p38 or p38-MAPK), and activator protein 1 (AP-1) signaling pathways were activated to mediated the induction of IL-6 level. Furthermore, downregulation of miR-7 was found to result in the lapatinib-induced activation of Raf-1signaling pathway and IL-6 expression. Taken together, our results indicated that lapatinib enhanced the migratory ability of TNBC by increasing IL-6 expression via the Raf-1, MAPK, JNK, p38, and AP-1 pathways. Citation Format: Yu-Chun Hsiao, Yun-Ju Chen, Chih-Hsin Tang, Wei-Chien Huang. Lapatinib induces IL-6 expression via MAPK pathway in triple-negative breast cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 157. doi:10.1158/1538-7445.AM2014-157

Interleukin 6 augments lung cancer chemotherapeutic resistance via ataxia-telangiectasia mutated/NF-kappaB pathway activation.

Although it is known that ataxia-telangiectasia mutated (ATM) and interleukin 6 (IL-6) contribute to multiple drug resistance (MDR) in tumor chemotherapy, the exact role of ATM activation in MDR resulting from increased IL-6 expression is still unclear. In the present study, we demonstrate that the activation of the ATM-NF-kappaB pathway, resulting from increased IL-6 expression, plays a central role in augmented chemoresistance in lung cancer cell lines. This result was supported by the increased expressions of Bcl-2, Mcl-1, Bcl-xl, and the upregulation of MDR-associated protein ABCG2. The higher level of IL-6 reveals not only higher ATM/NF-kappaB activity but also increased expressions of ABCG2, Bcl-2, Mcl-1 and Bcl-xl. Most importantly, lung cancer cells themselves upregulated IL-6 secretion by activating the p38/NF-kappaB pathway through treatment with cisplatin and camptothecin. Taken together, these findings demonstrate that chemotherapeutic agents increase IL-6 expression, hence activating the ATM/NF-kappaB pathway, augmenting anti-apoptotic protein expression and contributing to MDR. This indicates that both IL-6 and ATM are potential targets for the treatment of chemotherapeutic resistance in lung cancer.

Pseudaminic acid on Campylobacter jejuni flagella modulates dendritic cell IL-10 expression via Siglec-10 receptor: a novel flagellin-host interaction.

Introduction. Campylobacter jejuni is a leading cause of bacterial gastroenteritis worldwide. At present the identity of host-pathogen interactions that promote successful bacterial colonisation remain ill defined. Herein, we aimed to investigate C. jejuni-mediated effects on dendritic cell (DC) immunity.Results. We found C. jejuni to be a potent inducer of human and murine DC interleukin 10 (IL-10) in vitro, a cellular event that was MyD88- and p38 MAPK-signalling dependent. Utilizing a series of C. jejuni isogenic mutants we found the major flagellin protein, FlaA, modulated IL-10 expression, an intriguing observation as C. jejuni FlaA is not a TLR5 agonist. Further analysis revealed pseudaminic acid residues on the flagella contributed to DC IL-10 expression. We identified the ability of both viable C. jejuni and purified flagellum to bind to Siglec-10, an immune-modulatory receptor. In vitro infection of Siglec-10 overexpressing cells resulted in increased IL-10 expression in a p38-dependent manner. Detection of Siglec-10 on intestinal CD11c+ CD103+ DCs added further credence to the notion that this novel interaction may contribute to immune outcome during human infection.Conclusions. We propose that unlike the Salmonella Typhimurium flagella-TLR5 driven pro-inflammatory axis, C. jejuni flagella instead promote an anti-inflammatory axis via glycan-Siglec-10 engagement.

Bevacizumab terminates homeobox B9-induced tumor proliferation by silencing microenvironmental communication.

BackgroundHomeobox B9 (HOXB9), a transcriptional factor, regulates developmental processes and tumor progression and has recently been recognized as one of important transcriptional factors related to angiogenesis. This study aimed to investigate the role of HOXB9 in tumorigenesis and angiogenesis.MethodsWe examined the expression of HOXB9 in colorectal cancer using qPCR and in situ hybridization. We also examined the effect of HOXB9 overexpression in colorectal cancer using a proliferation assay, ELISA, a multiplex assay, and xenograft models. The clinical significance of HOXB9 was statistically evaluated in resected specimens.ResultsHOXB9 was expressed in colorectal cancer specimens. HOXB9 induced angiogenesis and tumor proliferation in vitro, which resulted in high tumorigenicity in vivo and poor overall survival. Bevacizumab, an anti-vascular endothelial growth factor (VEGF) antibody, remarkably suppressed tumor proliferation by inhibiting angiogenesis in HOXB9-overexpressing xenografts, and it improved overall survival and provided prolonged progression-free survival in HOXB9-overexpressing patients. A comprehensive multiplex assay of the supernatant of cancer cells co-cultured with human vascular endothelial cells and fibroblasts indicated significantly higher interleukin-6 (IL6) levels than those in the supernatant of monocultured cells. HOXB9 overexpression in clinical specimens was significantly correlated with increased IL6 expression. An IL6-neutralizing antibody inhibited VEGF secretion and tumor proliferation in the co-culture system.ConclusionsHOXB9 promotes the secretion of angiogenic factors, including VEGF, to induce tumor proliferation through microenvironmental production of cytokines including IL6 signaling. Moreover, silencing of VEGF or IL6 terminates cytokine release in tumor microenvironment. Thus, HOXB9 and IL6 may be potential biomarkers for bevacizumab treatment.

Protein kinase C delta (PKCδ)−extracellular-signal regulated kinase 1/2 (ERK1/2) signaling cascade regulates glycogen synthase kinase-3 (GSK-3) inhibition−mediated interleukin-10 (IL-10) expression in lipopolysaccharide (LPS)−induced endotoxemia (IRM5P.704)

Abstract Glycogen synthase kinase-3 (GSK-3) modulates a wide array of cellular processes, including embryonic development, cell differentiation, survival, and apoptosis. Recently, it was reported that a GSK-3 inhibitor attenuates lipopolysaccharide (LPS)−induced septic shock and regulates the mortality of endotoxemic mice. However, the detailed mechanism of reduced mortality via GSK-3 inhibition is not well defined. Herein, we showed that GSK-3 inhibition induces extracellular-signal regulated kinase 1/2 (ERK1/2) activation under LPS−stressed conditions via protein kinase C delta (PKCδ) activation. Furthermore, PKCδ−induced ERK1/2 activation by the inhibition of GSK-3 provoked the production of interleukin (IL)-10, playing a crucial role in regulating endotoxemia. Using a mitogen-activated protein kinase kinase-1 (MEK-1) and PKCδ inhibitor, we confirmed that GSK-3 inhibition induces PKCδ and subsequent ERK1/2 activation, resulting in increased IL-10 expression under LPS−treated conditions. We verified that septic shock caused by LPS is attenuated by GSK-3 inhibition using a GSK-3 inhibitor. This relieved endotoxemia induced by GSK-3 inhibition restored in ERK1/2−dependent manner. Taken together, IL-10 expression produced by GSK-3 inhibition−induced ERK1/2 activation via PKCδ relieved LPS−mediated endotoxemia. This finding suggests that IL-10 hyper-expression resulted from GSK-3 inhibition−induced ERK activation could be a new therapeutic pathway for endotoxemia.

A mutually beneficial relationship between hepatocytes and cardiomyocytes mitigates doxorubicin-induced toxicity

Use of doxorubicin (DOX) is limited by its toxicity in multiple organs. However, the relationship between different organs in response to DOX-induced injury is not well understood. We found that partial hepatectomy correlated with increased DOX-induced heart injury in vivo while supernatant prepared from DOX-treated hepatocytes mitigated DOX-induced cytotoxicity of cardiomyocytes in vitro. Meanwhile, the supernatant of DOX-treated cardiomyocytes mitigated DOX-induced cytotoxicity of hepatocytes. Investigation of the molecular mechanisms underlying these effects found that interleukin 6 (IL-6) was significantly up-regulated in DOX-treated tissues and cells, and supernatant from IL-6 treated cells had a similar effect to that from DOX-treated cells. Although the concentration of secreted IL-6 in supernatant from DOX-treated cells did not significantly differ, blockade of IL-6 signaling, by overexpressing SOCS3, suppressed expression of the downstream molecules trefoil factor family 3 (TFF3) and hepatocyte growth factor (HGF), impaired the mutually beneficial relationship between hepatocytes and cardiomyocytes. In conclusion, our study shows that a mutually beneficial relationship exists between hepatocytes and cardiomyocytes during the acute injury induced by DOX. Moreover, it demonstrates that this phenomenon may be indirectly caused by increased IL-6 expression and the activation of the downstream molecular mediators TFF3 and HGF in hepatocytes and cardiomyocytes, respectively.

Regulatory effect of miR-149 on interleukin-6 expression in silica-induced pulmonary fibrosis

To investigate the regulatory effect of miR-149 on interleukin-6 (IL-6) expression in silica-induced pulmonary fibrosis. A mouse model of pulmonary fibrosis was established using silica dust; the level of miR-149 in the lung tissues of mice with silica-induced pulmonary fibrosis was measured by quantitative real-time polymerase chain reaction (qRT-PCR), while the protein expression of IL-6 was measured by immunohistochemistry and Western blot. Type II alveolar epithelial cells (A549) and bronchial epithelial cells (HBE) were exposed to silica dust to establish a model; the level of miR-149 was measured by qRT-PCR, while the protein expression of IL-6 was measured by Western blot. A549 cells were transfected with miR-149 mimics and inhibitor in vitro, and the cellular expression of IL-6 was measured by Western blot. Serum samples from patients with coal workers' pneumoconiosis were examined by double-antibody sandwich ELISA to measure the protein expression of IL-6. At three time points after silica treatment, the miR-149 expression in lung tissues was significantly down-regulated while an evident increase in IL-6 expression was observed in lung tissues (P < 0.01). Silica-stimulated epithelial cell (A549 and HBE) had up-regulated IL-6 expression and down-regulated miR-149 expression (P < 0.01). Increased levels of miR-149 attenuated IL-6 expression, whereas adverse results were found when miR-149 was inhibited. Compared with that in control group, serum level of IL-6 was significantly increased in patients with stage II and III coal workers' pneumoconiosis (P < 0.01). Down-regulation of miR-149 and up-regulation of IL-6 might be involved in the progression of silica-induced pulmonary fibrosis; miR-149 could negatively regulate IL-6 expression.

GCN2-Dependent Metabolic Stress Is Essential for Endotoxemic Cytokine Induction and Pathology

Activated inflammatory macrophages can express indoleamine 2,3-dioxygenase (IDO) and thus actively deplete their own tryptophan supply; however, it is not clear how amino acid depletion influences macrophage behavior in inflammatory environments. In this report, we demonstrate that the stress response kinase GCN2 promotes macrophage inflammation and mortality in a mouse model of septicemia. In vitro, enzymatic amino acid consumption enhanced sensitivity of macrophages to the Toll-like receptor 4 (TLR4) ligand lipopolysaccharide (LPS) with significantly increased interleukin 6 (IL-6) production. Tryptophan withdrawal induced the stress response proteins ATF4 and CHOP/GADD153; however, LPS stimulation rapidly enhanced expression of both proteins. Moreover, LPS-driven cytokine production under amino acid-deficient conditions was dependent on GCN2, as GCN2 knockout (GCN2KO) macrophages had a significant reduction of cytokine gene expression after LPS stimulation. To test the in vivo relevance of these findings, monocytic-lineage-specific GCN2KO mice were challenged with a lethal dose of LPS intraperitoneally (i.p.). The GCN2KO mice showed reduced inflammatory responses, with decreased IL-6 and IL-12 expression correlating with significant reduction in animal mortality. Thus, the data show that amino acid depletion stress signals (via GCN2) synergize with proinflammatory signals to potently increase innate immune responsiveness.

Proteasome Inhibition Increases Recruitment of IκB Kinase β (IKKβ), S536P-p65, and Transcription Factor EGR1 to Interleukin-8 (IL-8) Promoter, Resulting in Increased IL-8 Production in Ovarian Cancer Cells

Proinflammatory and pro-angiogenic chemokine interleukin-8 (IL-8, CXCL8) contributes to ovarian cancer progression through its induction of tumor cell proliferation, survival, angiogenesis, and metastasis. Proteasome inhibition by bortezomib, which has been used as a frontline therapy in multiple myeloma, has shown only limited effectiveness in ovarian cancer and other solid tumors. However, the responsible mechanisms remain elusive. Here, we show that proteasome inhibition dramatically increases the IL-8 expression and release in ovarian cancer cells. The responsible mechanism involves an increased nuclear accumulation of IκB kinase β (IKKβ) and an increased recruitment of the nuclear IKKβ, p65-phosphorylated at Ser-536, and the transcription factor early growth response-1 (EGR-1) to the endogenous IL-8 promoter. Coimmunoprecipitation studies identified the nuclear EGR-1 associated with IKKβ and with p65, with preferential binding to S536P-p65. Both IKKβ activity and EGR-1 expression are required for the increased IL-8 expression induced by proteasome inhibition in ovarian cancer cells. Interestingly, in multiple myeloma cells the IL-8 release is not increased by bortezomib. Together, these data indicate that the increased IL-8 release may represent one of the underlying mechanisms responsible for the decreased effectiveness of proteasome inhibition in ovarian cancer treatment and identify IKKβ and EGR-1 as potential new targets in ovarian cancer combination therapies.