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1
Benveniste, E. N., J. Kwon, W. J. Chung, J. Sampson, K. Pandya i L. P. Tang. "Differential modulation of astrocyte cytokine gene expression by TGF-beta." Journal of Immunology 153, nr 11 (1.12.1994): 5210–21. http://dx.doi.org/10.4049/jimmunol.153.11.5210.
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Abstract In this study, we demonstrate that TGF-beta inhibits TNF-alpha expression, and induces/enhances IL-6 expression by primary rat astrocytes. Treatment of astrocytes with TGF-beta alone had no effect on TNF-alpha mRNA or protein expression; however, TGF-beta suppressed induction of TNF-alpha expression by three different stimuli (IFN-gamma/LPS, IFN-gamma/IL-1 beta, TNF-alpha) at both the protein and mRNA level. The extent of TGF-beta-mediated inhibition was greatest when astrocytes were pretreated with TGF-beta for 6 to 24 h, then exposed to the inducing stimuli. Inhibition of TNF-alpha mRNA steady-state levels by TGF-beta was a result of inhibition of TNF-alpha gene transcription, rather than degradation of the TNF-alpha message. In contrast, TGF-beta alone induced expression of IL-6 by astrocytes and synergized with two other cytokines, IL-1 beta and TNF-alpha, for enhanced IL-6 expression. TGF-beta-induced/enhanced IL-6 expression was mediated by transcriptional activation of the IL-6 gene. These results indicate that TGF-beta is an important regulator of cytokine production by astrocytes under inflammatory conditions in the brain.
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Kamijo, R., K. Takeda, M. Nagumo i K. Konno. "Effects of combinations of transforming growth factor-beta 1 and tumor necrosis factor on induction of differentiation of human myelogenous leukemic cell lines." Journal of Immunology 144, nr 4 (15.02.1990): 1311–16. http://dx.doi.org/10.4049/jimmunol.144.4.1311.
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Abstract Effects of transforming growth factor-beta 1 (TGF-beta 1), either alone or in combination with TNF, on the induction of differentiation of human myelogenous leukemic cell lines were examined. TGF-beta 1 alone induced differentiation of a human monocytic leukemia U-937 line into the cells with macrophage characteristics. When combined with TNF, TGF-beta 1 synergistically or additively induced differentiation associated properties. A human myeloblastic leukemia cell line, ML-1, differently responded to TGF-beta 1 in induction of differentiation. FcR activity and phagocytic activity induced by TNF were suppressed by TGF-beta 1. However, nitroblue tetrazolium reducing activity was synergistically induced by combinations of TGF-beta 1 and TNF. Scatchard analysis of TNF receptors indicated that the number of binding sites and dissociation constant of TNF for its receptors on U-937 or ML-1 cells were not changed by treatment with TGF-beta 1. Although IFN-gamma, IL-6, granulocyte CSF, and granulocyte-macrophage CSF-induced nitroblue tetrazolium reducing activity of U-937 cells, only IFN-gamma, and TNF induced it synergistically in combination with TGF-beta 1. Synergism between TGF-beta 1 and TNF was also observed in inhibition of growth of U-937 and ML-1 cells. Although TGF-beta 1 induction of differentiation of other monocytoid leukemic THP-1 cells was similar to that of U-937 cells, TGF-beta 1 only slightly induced differentiation of promyelocytic leukemic HL-60 cells, either alone or in combination with TNF. Our observations indicate that TGF-beta 1 strongly modulates differentiation and proliferation of human myelogenous leukemia cells, macrophage precursors.
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De Benedetti, F., LA Falk, LR Ellingsworth, FW Ruscetti i CR Faltynek. "Synergy between transforming growth factor-beta and tumor necrosis factor-alpha in the induction of monocytic differentiation of human leukemic cell lines". Blood 75, nr 3 (1.02.1990): 626–32. http://dx.doi.org/10.1182/blood.v75.3.626.626.
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Abstract We examined the effect of transforming growth factor-beta (TGF-beta) alone and in combinations with other factors on the growth and differentiation of the human promyelocytic cell line HL60 and the human monoblastic cell line U937. Treatment with TGF-beta alone did not significantly affect growth or differentiation of HL60 cells, while it significantly inhibited proliferation and induced monocytic differentiation of a small percentage of U937 cells. Combinations of TGF-beta and tumor necrosis factor-alpha (TNF-alpha) acted in synergy to inhibit cell proliferation and to induce monocytic differentiation of both HL60 and U937 cells. In contrast, no synergy was observed when HL60 cells were treated with TGF-beta in various combinations with interferon-alpha (IFN-alpha), interferon-gamma (IFN-gamma), and retinoic acid. Examination of TNF-alpha receptor expression on HL60 and U937 cells showed that these cell lines expressed comparable levels of high-affinity TNF-alpha binding sites. Treatment of HL60 and U937 cells with TGF-beta did not induce significant changes in TNF-alpha receptor expression in either cell line. In contrast, HL60 cells expressed much lower levels of TGF-beta receptors than did U937 cells. Treatment of both HL60 and U937 cells with TNF-alpha induced a dose-dependent increase in expression of TGF-beta receptors, suggesting that the synergy between TNF-alpha and TGF-beta may result, at least in part, from upregulation of TGF-beta receptor expression by TNF-alpha.
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De Benedetti, F., LA Falk, LR Ellingsworth, FW Ruscetti i CR Faltynek. "Synergy between transforming growth factor-beta and tumor necrosis factor-alpha in the induction of monocytic differentiation of human leukemic cell lines". Blood 75, nr 3 (1.02.1990): 626–32. http://dx.doi.org/10.1182/blood.v75.3.626.bloodjournal753626.
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We examined the effect of transforming growth factor-beta (TGF-beta) alone and in combinations with other factors on the growth and differentiation of the human promyelocytic cell line HL60 and the human monoblastic cell line U937. Treatment with TGF-beta alone did not significantly affect growth or differentiation of HL60 cells, while it significantly inhibited proliferation and induced monocytic differentiation of a small percentage of U937 cells. Combinations of TGF-beta and tumor necrosis factor-alpha (TNF-alpha) acted in synergy to inhibit cell proliferation and to induce monocytic differentiation of both HL60 and U937 cells. In contrast, no synergy was observed when HL60 cells were treated with TGF-beta in various combinations with interferon-alpha (IFN-alpha), interferon-gamma (IFN-gamma), and retinoic acid. Examination of TNF-alpha receptor expression on HL60 and U937 cells showed that these cell lines expressed comparable levels of high-affinity TNF-alpha binding sites. Treatment of HL60 and U937 cells with TGF-beta did not induce significant changes in TNF-alpha receptor expression in either cell line. In contrast, HL60 cells expressed much lower levels of TGF-beta receptors than did U937 cells. Treatment of both HL60 and U937 cells with TNF-alpha induced a dose-dependent increase in expression of TGF-beta receptors, suggesting that the synergy between TNF-alpha and TGF-beta may result, at least in part, from upregulation of TGF-beta receptor expression by TNF-alpha.
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HEGEWISCH, S. "TNF-induced cardiomyopathy". Lancet 335, nr 8684 (luty 1990): 294–95. http://dx.doi.org/10.1016/0140-6736(90)90115-l.
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Los, Marek, Malgorzata Mozoluk, Davide Ferrari, Anna Stepczynska, Christopher Stroh, Andrea Renz, Zdenko Herceg, Zhao-Qi Wang i Klaus Schulze-Osthoff. "Activation and Caspase-mediated Inhibition of PARP: A Molecular Switch between Fibroblast Necrosis and Apoptosis in Death Receptor Signaling". Molecular Biology of the Cell 13, nr 3 (marzec 2002): 978–88. http://dx.doi.org/10.1091/mbc.01-05-0272.
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Death ligands not only induce apoptosis but can also trigger necrosis with distinct biochemical and morphological features. We recently showed that in L929 cells CD95 ligation induces apoptosis, whereas TNF elicits necrosis. Treatment with anti-CD95 resulted in typical apoptosis characterized by caspase activation and DNA fragmentation. These events were barely induced by TNF, although TNF triggered cell death to a similar extent as CD95. Surprisingly, whereas the caspase inhibitor zVAD prevented CD95-mediated apoptosis, it potentiated TNF-induced necrosis. Cotreatment with TNF and zVAD was characterized by ATP depletion and accelerated necrosis. To investigate the mechanisms underlying TNF-induced cell death and its potentiation by zVAD, we examined the role of poly(ADP-ribose)polymerase-1 (PARP-1). TNF but not CD95 mediated PARP activation, whereas a PARP inhibitor suppressed TNF-induced necrosis and the sensitizing effect of zVAD. In addition, fibroblasts expressing a noncleavable PARP-1 mutant were more sensitive to TNF than wild-type cells. Our results indicate that TNF induces PARP activation leading to ATP depletion and subsequent necrosis. In contrast, in CD95-mediated apoptosis caspases cause PARP-1 cleavage and thereby maintain ATP levels. Because ATP is required for apoptosis, we suggest that PARP-1 cleavage functions as a molecular switch between apoptotic and necrotic modes of death receptor-induced cell death.
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Méndez-Samperio, Patricia, Marisol Hernandez-Garay i Angela Nuñez Vazquez. "Inhibition of Mycobacterium bovisBCG-Induced Tumor Necrosis Factor Alpha Secretion in Human Cells by Transforming Growth Factor β". Clinical Diagnostic Laboratory Immunology 5, nr 4 (1.07.1998): 588–91. http://dx.doi.org/10.1128/cdli.5.4.588-591.1998.
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ABSTRACT The effect of exogenous transforming growth factor β (TGF-β) onMycobacterium bovis BCG-induced tumor necrosis factor alpha (TNF-α) production by human mononuclear cells was studied. It was found that TNF-α production by human cells stimulated with BCG was significantly inhibited by TGF-β. The specificity of the observed inhibition was demonstrated, since the addition of an anti-TGF-β neutralizing monoclonal antibody completely reversed the inhibitory effect. Furthermore, the suppressive effect of TGF-β on TNF-α secretion in this system was not due to a direct cytotoxic effect, since cell viability was comparable in the presence or absence of TGF-β. Interestingly, our results demonstrated comparative suppressive effects of TGF-β and interleukin-10 on BCG-induced TNF-α secretion. Together, the data demonstrate, for the first time, that TGF-β inhibits BCG-induced TNF-α secretion by human cells.
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Panek, R. B., i E. N. Benveniste. "Class II MHC gene expression in microglia. Regulation by the cytokines IFN-gamma, TNF-alpha, and TGF-beta." Journal of Immunology 154, nr 6 (15.03.1995): 2846–54. http://dx.doi.org/10.4049/jimmunol.154.6.2846.
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Abstract The molecular mechanism(s) by which three cytokines (IFN-gamma, TNF-alpha, TGF-beta) affect class II MHC gene expression in primary rat microglia was examined. IFN-gamma is a potent inducer of the class II gene, and this induction is unaffected by treatment with either TNF-alpha or TGF-beta. Transient transfection of primary rat microglia with an HLA-DRA promoter linked to the chloramphenicol acetyltransferase reporter gene (DRA-CAT) demonstrated that IFN-gamma acts at the transcriptional level to induce class II MHC gene expression, and that TNF-alpha and TGF-beta have no influence on IFN-gamma-induced promoter activity. Experiments using a series of DRA substitution mutants that individually affect the W, X1, X2, or Y elements, as well as a double mutation in both X1 and X2, indicate that all four of these elements are required for responsiveness of the DRA promoter to IFN-gamma. The effect of IFN-gamma and TNF-alpha on DNA binding proteins by microglia was examined. A constitutive complex with specificity for the X2 box was detected in extracts from unstimulated microglia. IFN-gamma treatment changed this complex to migrate with slower mobility, and TNF-alpha had no effect on either the constitutive or IFN-gamma-induced complexes. These studies provide information on the molecular regulation of the class II MHC gene in microglia, a cell type critically involved in immune regulation within the central nervous system.
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Kochumon, Shihab, Amnah Al-Sayyar, Texy Jacob, Amal Hasan, Fahd Al-Mulla, Sardar Sindhu i Rasheed Ahmad. "TNF-α Increases IP-10 Expression in MCF-7 Breast Cancer Cells via Activation of the JNK/c-Jun Pathways". Biomolecules 11, nr 9 (13.09.2021): 1355. http://dx.doi.org/10.3390/biom11091355.
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IP-10 (also called CXCL10) plays a significant role in leukocyte homing to inflamed tissues, and increased IP-10 levels are associated with the pathologies of various inflammatory disorders, including type 2 diabetes, atherosclerosis, and cancer. TNF-α is a potent activator of immune cells and induces inflammatory cytokine expression in these cells. However, it is unclear whether TNF-α is able to induce IP-10 expression in MCF-7 breast cancer cells. We therefore determined IP-10 expression in TNF-α-treated MCF-7 cells and investigated the mechanism involved. Our data show that TNF-α induced/upregulated the IP-10 expression at both mRNA and protein levels in MCF-7 cells. Inhibition of JNK (SP600125) significantly suppressed the TNF-α-induced IP-10 in MCF-7 cells, while the inhibition of p38 MAPK (SB203580), MEK1/2 (U0126), and ERK1/2 (PD98059) had no significant effect. Furthermore, TNF-α-induced IP-10 expression was abolished in MCF-7 cells deficient in JNK. Similar results were obtained using MCF-7 cells deficient in c-Jun. Moreover, the JNK kinase inhibitor markedly reduced the TNF-α-induced JNK and c-Jun phosphorylation. The kinase activity of JNK induced by TNF-α stimulation of MCF-7 cells was significantly inhibited by SP600125. Altogether, our novel findings provide the evidence that TNF-α induces IP-10 expression in MCF-7 breast cancer cells via activation of the JNK/c-Jun signaling pathway.
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Kim, Han Geun, Joo Yun Kim, Min Geun Gim, Jung Min Lee i Dae Kyun Chung. "Mechanical stress induces tumor necrosis factor-α production through Ca2+ release-dependent TLR2 signaling". American Journal of Physiology-Cell Physiology 295, nr 2 (sierpień 2008): C432—C439. http://dx.doi.org/10.1152/ajpcell.00085.2008.
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We studied centrifugation-mediated mechanical stress-induced tumor necrosis factor-α (TNF-α) production in the monocyte-like cell line THP-1. The induction of TNF-α by mechanical stress was dependent on the centrifugation speed and produced the highest level of TNF-α after 1 h of stimulation. TNF-α production returned to normal levels after 24 h of stimulation. Mechanical stress also induced Toll-like receptor-2 (TLR2) mRNA in proportion to the expression of TNF-α. The inhibition of TLR2 signaling by dominant negative myeloid differentiation factor 88 (MyD88) blocked TNF-α expression response to mechanical stress. After transient overexpression of TLR2 in HEK-293 cells, mechanical stress induced TNF-α mRNA production. Interestingly, mechanical stress activated the c-Src-dependent TLR2 phosphorylation, which is necessary to induce Ca2+ fluxes. When THP-1 cells were pretreated with BAPTA-AM, thapsigargin, and NiCl2·6H2O, followed by mechanical stimulation, both TLR2 and TNF-α production were inhibited, indicating that centrifugation-mediated mechanical stress induces both TLR2 and TNF-α production through Ca2+ releases from intracellular Ca2+ stores following TLR2 phosphorylation. In addition, TNF-α treatment in THP-1 cells induced TLR2 production in response to mechanical stress, whereas the preincubation of anti-TNF-α antibody scarcely induced the mechanical stress-mediated production of TLR2, indicating that TNF-α produced by mechanically stimulated THP-1 cells affected TLR2 production. We concluded that TNF-α production induced by centrifugation-mediated mechanical stress is dependent on MyD88-dependent TLR2 signaling that is associated with Ca2+ release and that TNF-α production induced by mechanical stress affects TLR2 production.
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Lovibond, Alison C., S. Jaharul Haque, Timothy J. Chambers i Simon W. Fox. "TGF-β-induced SOCS3 expression augments TNF-α-induced osteoclast formation". Biochemical and Biophysical Research Communications 309, nr 4 (październik 2003): 762–67. http://dx.doi.org/10.1016/j.bbrc.2003.08.068.
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Ishinaga, Hajime, Hirofumi Jono, Jae Hyang Lim, Kensei Komatsu, Xiangbin Xu, Jiyun Lee, Chang-Hoon Woo i in. "Synergistic induction of nuclear factor-κB by transforming growth factor-β and tumour necrosis factor-α is mediated by protein kinase A-dependent RelA acetylation". Biochemical Journal 417, nr 2 (23.12.2008): 583–91. http://dx.doi.org/10.1042/bj20080781.
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The TGF-β (transforming growth factor-β) pathway represents an important signalling pathway involved in regulating diverse biological processes, including cell proliferation, differentiation and inflammation. Despite the critical role for TGF-β in inflammatory responses, its role in regulating NF-κB (nuclear factor-κB)-dependent inflammatory responses still remains unknown. In the present study we show that TGF-β1 synergizes with proinflammatory cytokine TNF-α (tumour necrosis factor-α) to induce NF-κB activation and the resultant inflammatory response in vitro and in vivo. TGF-β1 synergistically enhances TNF-α-induced NF-κB DNA binding activity via induction of RelA acetylation. Moreover, synergistic enhancement of TNF-α-induced RelA acetylation and DNA-binding activity by TGF-β1 is mediated by PKA (protein kinase A). Thus the present study reveals a novel role for TGF-β in inflammatory responses and provides new insight into the regulation of NF-κB by TGF-β signalling.
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Faquin, WC, TJ Schneider i MA Goldberg. "Effect of inflammatory cytokines on hypoxia-induced erythropoietin production". Blood 79, nr 8 (15.04.1992): 1987–94. http://dx.doi.org/10.1182/blood.v79.8.1987.bloodjournal7981987.
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The effects of the inflammatory cytokines interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-6, transforming growth factor-beta (TGF-beta), and tumor necrosis factor-alpha (TNF-alpha) on erythropoietin (Epo) production in Hep3B cells were examined. The addition of IL-1 alpha, IL- 1 beta, or TNF-alpha resulted in a dose-dependent inhibition of hypoxia- induced Epo production by as much as 89%. IL-1 beta was the most effective cytokine tested, demonstrating half-maximal inhibition at 0.4 U/mL compared with 1.0 and 10.0 U/mL for IL-1 alpha and TNF-alpha, respectively. TGF-beta also inhibited hypoxia-induced Epo production, but only by as much as 56%. In contrast to IL-1 alpha, IL-1 beta, TNF- alpha, and TGF-beta, the addition of IL-6 to hypoxic Hep3B cells resulted in a dose-dependent stimulation of hypoxia-induced Epo production by as much as 81%. However, IL-6 did not stimulate Epo synthesis in the absence of hypoxia, and was thus synergistic with hypoxia in inducing Epo production. Combinations of IL-1 alpha, TNF- alpha, and IL-6 were found to be additive in their effects on hypoxia- induced Epo production. By Northern blot analysis, Epo messenger RNA levels in Hep3B cells grown in 1% O2 were decreased when concurrently exposed to either IL-1 alpha or TNF-alpha. The effects that IL-1 alpha, IL-1 beta, TGF-beta, TNF-alpha, and IL-6 have on hypoxia-induced Epo production may provide new insights into the signal transduction pathway by which hypoxia leads to changes in gene expression. In addition, the effects of these inflammatory cytokines on hypoxia- induced Epo production in vitro suggest that in various inflammatory disorders these cytokines may affect Epo production in vivo and may play a significant role in the pathogenesis of the anemia of chronic disease.
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Pathare, S. K., C. Heycock i J. Hamilton. "TNF blocker-induced thrombocytopenia". Rheumatology 45, nr 10 (9.08.2006): 1313–14. http://dx.doi.org/10.1093/rheumatology/kel204.
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Williams, E. L., S. Gadola i C. J. Edwards. "Anti-TNF-induced lupus". Rheumatology 48, nr 7 (4.05.2009): 716–20. http://dx.doi.org/10.1093/rheumatology/kep080.
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Hu, Ping, Zhang Han, Anthony D. Couvillon, Randal J. Kaufman i John H. Exton. "Autocrine Tumor Necrosis Factor Alpha Links Endoplasmic Reticulum Stress to the Membrane Death Receptor Pathway through IRE1α-Mediated NF-κB Activation and Down-Regulation of TRAF2 Expression". Molecular and Cellular Biology 26, nr 8 (15.04.2006): 3071–84. http://dx.doi.org/10.1128/mcb.26.8.3071-3084.2006.
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ABSTRACT NF-κB is critical for determining cellular sensitivity to apoptotic stimuli by regulating both mitochondrial and death receptor apoptotic pathways. The endoplasmic reticulum (ER) emerges as a new apoptotic signaling initiator. However, the mechanism by which ER stress activates NF-κB and its role in regulation of ER stress-induced cell death are largely unclear. Here, we report that, in response to ER stress, IKK forms a complex with IRE1α through the adapter protein TRAF2. ER stress-induced NF-κB activation is impaired in IRE1α knockdown cells and IRE1α−/− MEFs. We found, however, that inhibiting NF-κB significantly decreased ER stress-induced cell death in a caspase-8-dependent manner. Gene expression analysis revealed that ER stress-induced expression of tumor necrosis factor alpha (TNF-α) was IRE1α and NF-κB dependent. Blocking TNF receptor 1 signaling significantly inhibited ER stress-induced cell death. Further studies suggest that ER stress induces down-regulation of TRAF2 expression, which impairs TNF-α-induced activation of NF-κB and c-Jun N-terminal kinase and turns TNF-α from a weak to a powerful apoptosis inducer. Thus, ER stress induces two signals, namely TNF-α induction and TRAF2 down-regulation. They work in concert to amplify ER-initiated apoptotic signaling through the membrane death receptor.
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Kubota, Takeshi, Jidong Fang, Zhiwei Guan, Richard A. Brown i James M. Krueger. "Vagotomy attenuates tumor necrosis factor-α-induced sleep and EEG δ-activity in rats". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 280, nr 4 (1.04.2001): R1213—R1220. http://dx.doi.org/10.1152/ajpregu.2001.280.4.r1213.
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Much evidence suggests that tumor necrosis factor-α (TNF-α) is involved in the regulation of physiological sleep. However, it remains unclear whether peripheral administration of TNF-α induces sleep in rats. Furthermore, the role of the vagus nerve in the somnogenic actions of TNF-α had not heretofore been studied. Four doses of TNF-α were administered intraperitoneally just before the onset of the dark period. The three higher doses of TNF-α (50, 100, and 200 μg/kg) dose dependently increased nonrapid eye movement sleep (NREMS), accompanied by increases in electroencephalogram (EEG) slow-wave activity. TNF-α increased EEG δ-power and decreased EEG α- and β-power during the initial 3 h after injection. In vagotomized rats, the NREMS responses to 50 or 100 μg/kg of TNF-α were attenuated, while significant TNF-α-induced increases in NREMS were observed in a sham-operated group. Moreover, the vagotomized rats failed to exhibit the increase in EEG δ-power induced by TNF-α intraperitoneally. These results suggest that peripheral TNF-α can induce NREMS and vagal afferents play an important role in the effects of peripheral TNF-α and EEG synchronization on sleep. Intraperitoneal TNF-α failed to affect brain temperature at the doses tested, thereby demonstrating that TNF-α-induced sleep effects are, in part, independent from its effects on brain temperature. Results are consistent with the hypothesis that a cytokine network is involved in sleep regulation.
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Levy, Ofer, Rochelle M. Jean-Jacques, Colette Cywes, Richard B. Sisson, Kol A. Zarember, Paul J. Godowski, Jennifer L. Christianson i in. "Critical Role of the Complement System in Group B Streptococcus-Induced Tumor Necrosis Factor Alpha Release". Infection and Immunity 71, nr 11 (listopad 2003): 6344–53. http://dx.doi.org/10.1128/iai.71.11.6344-6353.2003.
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ABSTRACT Group B Streptococcus (GBS) is a major cause of newborn sepsis and meningitis and induces systemic release of tumor necrosis factor alpha (TNF-α), believed to play a role in morbidity and mortality. While previous studies have shown that GBS can induce TNF-α release from monocytes and macrophages, little is known about the potential modulating effect of plasma or serum on GBS-induced TNF-α release, and there are conflicting reports as to the host receptors involved. In a human whole-blood assay system, GBS type III COH-1 potently induced substantial monocyte TNF-α release in adult peripheral blood and, due to a higher concentration of monocytes, 10-fold-greater TNF-α release in newborn cord blood. Remarkably, GBS-induced TNF-α release from human monocytes was enhanced ∼1,000-fold by heat-labile serum components. Experiments employing C2-, C3-, or C7-depleted serum demonstrated that C3 activation via the alternative pathway is crucial for potent GBS-induced TNF-α release. Accordingly, whole blood from C3-deficient mice demonstrated significantly reduced GBS-induced TNF-α release. Preincubation with human serum enhanced the TNF-α-inducing activity of GBS in a C3- and factor B-dependent manner, implying deposition of complement components via the alternative pathway. GBS-induced TNF-α release was inhibited by monoclonal antibodies directed against each of the components of CR3 and CR4: the common integrin β subunit CD18 and the α subunits CD11b (of CR3) and CD11c (of CR4). Blood derived from CR3 (CD11b/CD18)-deficient mice demonstrated a markedly diminished TNF-α response to GBS. We conclude that the ability of plasma and serum to greatly amplify GBS-induced TNF-α release reflects the activity of the alternative complement pathway that deposits fragments on GBS and thereby enhances CR3- and CR4-mediated monocyte activation.
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Watanabe, Y., H. Osaki i T. Akaike. "TNF-alpha bifunctionally induces proliferation in primary hepatocytes: role of cell anchorage and spreading." Journal of Immunology 159, nr 10 (15.11.1997): 4840–47. http://dx.doi.org/10.4049/jimmunol.159.10.4840.
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Abstract In the absence of a growth factor or an appropriate extracellular matrix (ECM), cells are arrested in the G0/G1 phase. In this report, we demonstrate the evidence that TNF-alpha induced DNA synthesis of primary mouse hepatocytes in vitro by activating two distinct pathways. TNF-alpha induced drastic spreading of hepatocytes on hydrophobic plastic, while the adhesion was not influenced. The effect was time and dose dependent. The cell spreading was accompanied by the phosphorylation of paxillin, indicating the stimulation of focal adhesion molecules. TNF-alpha-induced spreading of hepatocytes was not transient, and kinetic analysis and morphologic observation suggest that the effect was different from epidermal growth factor- or hepatocyte growth factor-induced transient hepatocyte spreading. TNF-alpha-induced hepatocyte spreading was blocked by cytochalasin D, Arg-Gly-Asp peptides, cycloheximide, or anti-integrin beta1 Ab. Results of competitive PCR for ECM proteins demonstrated that TNF-alpha increased the expression of laminin alpha3 and gamma1 chains in hepatocytes. These data suggested that TNF-alpha induced cell anchorage for hepatocytes by up-regulating ECM production. More importantly, TNF-alpha, but neither epidermal growth factor nor hepatocyte growth factor, induced DNA synthesis following the spreading in primary hepatocytes on hydrophobic plastic, while mere cell spreading on collagen did not induce DNA synthesis. The DNA synthesis was blocked by the inhibition of either cell spreading or DNA polymerase, demonstrating that TNF-alpha induced DNA synthesis in primary hepatocytes by activating two distinct pathways, i.e., forming the scaffold and inducing growth signals. Taken together, TNF-alpha bifunctionally regulates the proliferation of primary hepatocytes, serving as both an ECM inducer and a growth factor.
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Dybedal, Ingunn, Fengan Guan, Ole Johan Borge, Ole Petter Veiby, Veslemøy Ramsfjell, Shigekazu Nagata i Sten Eirik W. Jacobsen. "Transforming Growth Factor-β1 Abrogates Fas-Induced Growth Suppression and Apoptosis of Murine Bone Marrow Progenitor Cells". Blood 90, nr 9 (1.11.1997): 3395–403. http://dx.doi.org/10.1182/blood.v90.9.3395.
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Abstract Fas, a member of the tumor necrosis factor (TNF ) receptor superfamily is a critical downregulator of cellular immune responses. Proinflammatory cytokines like interferon-γ (IFN-γ) and TNF-α can induce Fas expression and render hematopoietic progenitor cells susceptible to Fas-induced growth suppression and apoptosis. Transforming growth factor-β1 (TGF-β1 ) is an essential anti-inflammatory cytokine, thought to play a key role in regulating hematopoiesis. In the present studies we investigated whether TGF-β1 might regulate growth suppression and apoptosis of murine hematopoietic progenitor cells signaled through Fas. In the presence of TNF, activation of Fas almost completely blocked clonogenic growth of lineage-depleted (Lin−) bone marrow (BM) progenitor cells in response to granulocyte-macrophage colony-stimulating factor (GM-CSF ), CSF-1, or a combination of multiple cytokines. Whereas TGF-β1 alone had no effect or stimulated growth in response to these cytokines, it abrogated Fas-induced growth suppression. Single-cell studies and delayed addition of TGF-β1 showed that the ability of TGF-β1 to inhibit Fas-induced growth suppression was directly mediated on the progenitor cells and not indirect through potentially contaminating accessory cells. Furthermore, TGF-β1 blocked Fas-induced apoptosis of Lin− BM cells, but did not affect Fas-induced apoptosis of thymocytes. TGF-β1 also downregulated the expression of Fas on Lin− BM cells. Thus, TGF-β1 potently and directly inhibits activation-dependent and Fas-mediated growth suppression and apoptosis of murine BM progenitor cells, an effect that appears to be distinct from its ability to induce progenitor cell-cycle arrest. Consequently, TGF-β1 might act to protect hematopoietic progenitor cells from enhanced Fas expression and function associated with proinflammatory responses.
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Faquin, WC, TJ Schneider i MA Goldberg. "Effect of inflammatory cytokines on hypoxia-induced erythropoietin production". Blood 79, nr 8 (15.04.1992): 1987–94. http://dx.doi.org/10.1182/blood.v79.8.1987.1987.
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Abstract The effects of the inflammatory cytokines interleukin-1 alpha (IL-1 alpha), IL-1 beta, IL-6, transforming growth factor-beta (TGF-beta), and tumor necrosis factor-alpha (TNF-alpha) on erythropoietin (Epo) production in Hep3B cells were examined. The addition of IL-1 alpha, IL- 1 beta, or TNF-alpha resulted in a dose-dependent inhibition of hypoxia- induced Epo production by as much as 89%. IL-1 beta was the most effective cytokine tested, demonstrating half-maximal inhibition at 0.4 U/mL compared with 1.0 and 10.0 U/mL for IL-1 alpha and TNF-alpha, respectively. TGF-beta also inhibited hypoxia-induced Epo production, but only by as much as 56%. In contrast to IL-1 alpha, IL-1 beta, TNF- alpha, and TGF-beta, the addition of IL-6 to hypoxic Hep3B cells resulted in a dose-dependent stimulation of hypoxia-induced Epo production by as much as 81%. However, IL-6 did not stimulate Epo synthesis in the absence of hypoxia, and was thus synergistic with hypoxia in inducing Epo production. Combinations of IL-1 alpha, TNF- alpha, and IL-6 were found to be additive in their effects on hypoxia- induced Epo production. By Northern blot analysis, Epo messenger RNA levels in Hep3B cells grown in 1% O2 were decreased when concurrently exposed to either IL-1 alpha or TNF-alpha. The effects that IL-1 alpha, IL-1 beta, TGF-beta, TNF-alpha, and IL-6 have on hypoxia-induced Epo production may provide new insights into the signal transduction pathway by which hypoxia leads to changes in gene expression. In addition, the effects of these inflammatory cytokines on hypoxia- induced Epo production in vitro suggest that in various inflammatory disorders these cytokines may affect Epo production in vivo and may play a significant role in the pathogenesis of the anemia of chronic disease.
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Yao, Zhenqiang, Stephen J. Getting i Ian C. Locke. "Regulation of TNF-Induced Osteoclast Differentiation". Cells 11, nr 1 (31.12.2021): 132. http://dx.doi.org/10.3390/cells11010132.
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Increased osteoclast (OC) differentiation and activity is the critical event that results in bone loss and joint destruction in common pathological bone conditions, such as osteoporosis and rheumatoid arthritis (RA). RANKL and its decoy receptor, osteoprotegerin (OPG), control OC differentiation and activity. However, there is a specific concern of a rebound effect of denosumab discontinuation in treating osteoporosis. TNFα can induce OC differentiation that is independent of the RANKL/RANK system. In this review, we discuss the factors that negatively and positively regulate TNFα induction of OC formation, and the mechanisms involved to inform the design of new anti-resorptive agents for the treatment of bone conditions with enhanced OC formation. Similar to, and being independent of, RANKL, TNFα recruits TNF receptor-associated factors (TRAFs) to sequentially activate transcriptional factors NF-κB p50 and p52, followed by c-Fos, and then NFATc1 to induce OC differentiation. However, induction of OC formation by TNFα alone is very limited, since it also induces many inhibitory proteins, such as TRAF3, p100, IRF8, and RBP-j. TNFα induction of OC differentiation is, however, versatile, and Interleukin-1 or TGFβ1 can enhance TNFα-induced OC formation through a mechanism which is independent of RANKL, TRAF6, and/or NF-κB. However, TNFα polarized macrophages also produce anabolic factors, including insulin such as 6 peptide and Jagged1, to slow down bone loss in the pathological conditions. Thus, the development of novel approaches targeting TNFα signaling should focus on its downstream molecules that do not affect its anabolic effect.
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Hsu, Chih-Kai, I.-Ta Lee, Chih-Chung Lin, Li-Der Hsiao i Chuen-Mao Yang. "Nox2/ROS-dependent human antigen R translocation contributes to TNF-α-induced SOCS-3 expression in human tracheal smooth muscle cells". American Journal of Physiology-Lung Cellular and Molecular Physiology 306, nr 6 (15.03.2014): L521—L533. http://dx.doi.org/10.1152/ajplung.00274.2013.
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Elevated levels of TNF-α have been detected in the airway fluids, which may induce upregulation of inflammatory proteins. Suppressors of cytokine signaling (SOCS)-3 proteins can be induced by various cytokines and negatively regulated inflammatory responses. Although TNF-α has been shown to induce SOCS-3 expression, the mechanisms underlying TNF-α-induced SOCS-3 expression in human tracheal smooth muscle cells (HTSMCs) remain unclear. Here, we showed that TNF-α induced SOCS-3 expression, which was inhibited by pretreatment with the inhibitor of transcription level (actinomycin D), translation level (cycloheximide), JNK1/2 (SP600125), MEK1/2 (U0126), NADPH oxidase (Nox; apocynin and diphenyleneiodonium chloride), or reactive oxygen species (ROS; N-acetyl-l-cysteine) and transfection with siRNA of JNK1, p47 phox, p42, Nox2, or human antigen R (HuR). In addition, TNF-α-stimulated JNK1/2 and p42/p44 MAPK phosphorylation, Nox activation, and ROS generation were inhibited by pretreatment with U0126 or SP600125 and transfection with siRNA of JNK1 or p42. We further showed that TNF-α markedly induced HuR protein expression and translocation from the nucleus to the cytosol, which could stabilize SOCS-3 mRNA. Moreover, TNF-α-enhanced HuR translocation was reduced by transfection with siRNA of p42, JNK1, or p47 phox. These results suggested that TNF-α induces SOCS-3 protein expression and mRNA stabilization via a TNFR1/JNK1/2, p42/p44 MAPK/Nox2/ROS-dependent HuR signaling in HTSMCs. Lipopolysaccharide (LPS) has been shown to play a key role in inflammation via induction of adhesion molecules and then causes airway and lung injury. Moreover, we also demonstrated that overexpression of SOCS-3 protects against LPS-induced adhesion molecules expression and airway inflammation.
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de Hemptinne, Virginie, Dieter Rondas, Joël Vandekerckhove i Katia Vancompernolle. "Tumour necrosis factor induces phosphorylation primarily of the nitric-oxide-responsive form of glyoxalase I". Biochemical Journal 407, nr 1 (12.09.2007): 121–28. http://dx.doi.org/10.1042/bj20070379.
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We have previously shown that TNF (tumour necrosis factor) induces phosphorylation of GLO1 (glyoxalase I), which is required for cell death in L929 cells. In the present paper, we show that the TNF-induced phosphorylation of GLO1 occurs primarily on the NO (nitric oxide)-responsive form of GLO1. In addition, analysis of several cysteine mutants of GLO1 indicated that Cys-138, in combination with either Cys-18 or Cys-19, is a crucial target residue for the NO-mediated modification of GLO1. Furthermore, the NO-donor GSNO (S-nitrosogluthathione) induces NO-mediated modification of GLO1 and enhances the TNF-induced phosphorylation of this NO-responsive form. GSNO also strongly promotes TNF-induced cell death. By the use of pharmacological inhibition of iNOS (inducible NO synthase) and overexpression of mutants of GLO1 that are deficient for the NO-mediated modification, we have shown that the NO-mediated modification of GLO1 is not a requirement for TNF-induced phosphorylation or TNF-induced cell death respectively. In summary, these data suggest that the TNF-induced phosphorylation of GLO1 is the dominant factor for cell death.
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Jacobs-Helber, Sarah M., Kwan-ho Roh, Daniel Bailey, Emmanuel N. Dessypris, John J. Ryan, Jingchun Chen, Amittha Wickrema, Dwayne L. Barber, Paul Dent i Stephen T. Sawyer. "Tumor necrosis factor-alpha expressed constitutively in erythroid cells or induced by erythropoietin has negative and stimulatory roles in normal erythropoiesis and erythroleukemia". Blood 101, nr 2 (15.01.2003): 524–31. http://dx.doi.org/10.1182/blood-2001-11-0084.
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Binding of erythropoietin (EPO) to its receptor (EPOR) on erythroid cells induces the activation of numerous signal transduction pathways, including the mitogen-activated protein kinase Jun-N-terminal kinase (JNK). In an effort to understand the regulation of EPO-induced proliferation and JNK activation, we have examined the role of potential autocrine factors in the proliferation of the murine erythroleukemia cell line HCD57. We report here that treatment of these cells with EPO induced the expression and secretion of tumor necrosis factor alpha (TNF-α). EPO-dependent proliferation was reduced by the addition of neutralizing antibodies to TNF-α, and exogenously added TNF-α induced proliferation of HCD57 cells. EPO also could induce TNF-α expression in BAF3 and DA3 myeloid cells ectopically expressing EPOR. Addition of TNF-α activated JNK in HCD57 cells, and the activity of JNK was partially inhibited by addition of a TNF-α neutralizing antibody. Primary human and murine erythroid progenitors expressed TNF-α in either an EPO-dependent or constitutive manner. However, TNF-α had an inhibitory effect on both immature primary human and murine cells, suggestive that the proliferative effects of TNF-α may be limited to erythroleukemic cells. This study suggests a novel role for autocrine TNF-α expression in the proliferation of erythroleukemia cells that is distinct from the effect of TNF-α in normal erythropoiesis.
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Woo, Chang-Hoon, Jae-Hyang Lim i Jae-Hong Kim. "VCAM-1 upregulation via PKCδ-p38 kinase-linked cascade mediates the TNF-α-induced leukocyte adhesion and emigration in the lung airway epithelium". American Journal of Physiology-Lung Cellular and Molecular Physiology 288, nr 2 (luty 2005): L307—L316. http://dx.doi.org/10.1152/ajplung.00105.2004.
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Vascular cell adhesion molecule (VCAM)-1 plays a central role in the recruitment of inflammatory cells, and its expression is rapidly induced by proinflammatory cytokines such as TNF-α. In the present study, we show that pretreatment with rottlerin, a specific inhibitor of protein kinase C (PKC)-δ, or transient transfection with antisense PKCδ oligonucleotides significantly inhibits TNF-α-induced expression of VCAM-1, but not of intercellular adhesion molecule (ICAM)-1 in human lung epithelium A549 cells. In addition, TNF-α was shown to induce the expression of VCAM-1 in a p38 kinase-dependent manner; also, TNF-α-induced p38 kinase activation was blocked by inhibition of PKCδ, suggesting that p38 kinase is apparently situated downstream of PKCδ in the TNF-α-signaling pathway to VCAM-1 expression. Notably, inhibition of the PKCδ-p38 kinase cascade also attenuated the TNF-α-induced adhesion of neutrophils to lung epithelium and the trafficking of leukocytes across the epithelium into the airway lumen in vivo. Together, these findings indicate that signaling via PKCδ-p38 kinase-linked cascade specifically induces expression of VCAM-1 in lung epithelium in response to TNF-α and that this effect is both functionally and clinically significant.
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Liu, Sen, Yan Wang, Huijuan Wen, Xiaofang Sun i Yu Wang. "Hydroxysafflor Yellow A Inhibits TNF-α-Induced Inflammation of Human Fetal Lung Fibroblasts via NF-κB Signaling Pathway". Evidence-Based Complementary and Alternative Medicine 2019 (26.12.2019): 1–9. http://dx.doi.org/10.1155/2019/4050327.
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Objective. Hydroxysafflor yellow A (HSYA), an effective ingredient of the Chinese herb Carthamus tinctorius L, attenuated bleomycin-induced pulmonary fibrosis in mice. This study is to investigate the effect of HSYA on the proliferation and inflammatory level of human fetal lung fibroblasts (MRC-5 cells) induced by tumor necrosis factor-α (TNF-α) and explore the underlying mechanisms. Methods. MRC-5 cells were treated with different concentrations of TNF-α, HSYA, or/and etanercept (ENCP, TNF-α receptor (TNFR1) antagonist, 500 ng/mL) before cell proliferation was detected. The laser confocal microscope was used to observe the role of HSYA in binding of TNF-α and its receptor. Co-immunoprecipitation was used to detect the binding of TNFR1 and TAK1-TAB2 complex. Real-time quantitative RT-PCR and western blot were used to detect the expressions of inflammation-related cytokines and proteins related with the NF-κB pathway. Luciferase reporter gene assay and chromatin coprecipitation method were used to detect the interaction between AP-1 and TGF-β1 promoter. Results. TNF-α (5 ng/mL) was used to induce inflammation and proliferation in MRC-5 cells. HSYA can partially suppress the stimulation of TNF-α on proliferation and inflammatory response of MRC-5 cells. HSYA could compete with TNF-α to bind with TNFR1 and hamper the binding of TNFR1 to TAK1-TAB2 complex. In addition, HSYA could also inhibit the activation of the NF-κB signal pathway and suppress the binding of TGF-β1 promoter with AP-1. Conclusion. Evidence in this study suggested that HSYA affects TNF-α-induced proliferation and inflammatory response of MRC-5 cells through the NF-κB/AP-1 signaling pathway, which may provide theoretical basis for HSYA treatment in pulmonary fibrosis.
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Suda, T., i A. Zlotnik. "In vitro induction of CD8 expression on thymic pre-T cells. I. Transforming growth factor-beta and tumor necrosis factor-alpha induce CD8 expression on CD8- thymic subsets including the CD25+CD3-CD4-CD8- pre-T cell subset." Journal of Immunology 148, nr 6 (15.03.1992): 1737–45. http://dx.doi.org/10.4049/jimmunol.148.6.1737.
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Abstract We previously reported that IL-7 maintains the viability and differentiation potential of CD25 (IL-2R p55) positive CD3-CD4-CD8- thymic pre-T cells in vitro. This culture system is suitable for studying signals that regulate differentiation of T cell precursors in the thymus. In this study, we screened cytokines for their capacity to induce CD4 or CD8 in murine thymic pre-T cells cultured with IL-7. Of 15 cytokines tested, only transforming growth factor (TGF-beta) and TNF-alpha induced CD8 (Lyt-2), while no cytokine was able to induce CD4 on CD25+CD3-CD4-CD8- thymocytes. The combination of TGF-beta and TNF-alpha was synergistic, and the majority of cells recovered after 2 to 3 days in culture expressed CD8 (but not CD3 or CD4). A similar effect of TGF-beta and TNF-alpha was observed using day-15 fetal thymocytes, CD3+CD4-CD8- or CD3+CD4+CD8- adult thymocytes, although the combination of these cytokines resulted in an additive rather than a synergistic effect in these subsets. In contrast, neither TGF-beta nor TNF-alpha induced CD8 expression on splenic CD4+CD8- T cells. These observations suggest a role for these cytokines in the induction of CD8 expression in CD8- thymocyte subsets including CD3-CD4-CD8- thymic pre-T cells.
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Putra, Agung, Fatkhan Baitul Ridwan, Allisha Irwaniyanti Putridewi, Azizah Retno Kustiyah, Ken Wirastuti, Nur Anna Chalimah Sadyah, Ika Rosdiana i Delfitri Munir. "The Role of TNF-α induced MSCs on Suppressive Inflammation by Increasing TGF-β and IL-10". Open Access Macedonian Journal of Medical Sciences 6, nr 10 (4.10.2018): 1779–83. http://dx.doi.org/10.3889/oamjms.2018.404.
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BACKGROUND: Mesenchymal stem cells (MSCs) may serve as immunoregulators by producing various anti-inflammatory molecules. Under sufficient level of TNF-α, MSCs become activated and adopt immune-suppressive phenotype (MSCs type-2) by releasing various anti-inflammatory molecule including TGF-β and IL-10. However, the ability of MSC itself to produce IL-10 under TNF-α stimulation and the correlation of TGF-β production of MSCs to IL-10 level remains to be elucidated.
AIM: In this study, MSCs were activated with various TNF-α doses to determine the increase of IL-10 and TGF-β level as well as its correlation.
MATERIAL AND METHODS: This study used post-test only control group design, by using 3 study groups, consist of 1 control (C) and 2 treatments (T) (TNF-α = 5 and 10 ng/mL) with triplicate induced in MSC for 24 hours, then the levels of IL-10 and TGF-β were measured by using ELISA assay.
RESULTS: The results of this study showed a significant increase of TGF-β and IL-10 levels (p < 0.05) at TNF-α 5 and 10 ng/mL dose of TNF-α. Moreover, there was a significant negative correlation between TGF-β and IL-10 level on 5 and 10 ng/mL dose TNF-α treatment.
CONCLUSION: Based on our study, we conclude that the 5 ng/mL dose of TNF-α is a sufficient dose for MSCs to suppress the inflammatory milieu. The higher increase of TGF beta is due to the controlled inflammation by IL-10.
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Sterns, Theo, Nils Pollak, Bernd Echtenacher i Daniela N. Männel. "Divergence of Protection Induced by Bacterial Products and Sepsis-Induced Immune Suppression". Infection and Immunity 73, nr 8 (sierpień 2005): 4905–12. http://dx.doi.org/10.1128/iai.73.8.4905-4912.2005.
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ABSTRACT Susceptibility to bacterial infections after a primary immune stimulation differs drastically depending on the presensitization of the innate immune system. To determine the conditions that either induce protection or enhanced susceptibility to infection with Salmonella enterica serovar Typhimurium, we pretreated mice either with tumor necrosis factor (TNF), whole killed bacteria, or sublethal cecal ligation and puncture (CLP) as a mouse model for septic peritonitis. Impaired production of the cytokines TNF, interleukin-6 (IL-6), and IL-10 was induced by these pretreatment schedules, with TNF-signaling not being essential for this effect. Injection of TNF or killed bacteria enhanced survival of mice infected subsequently with serovar Typhimurium. In contrast, sepsis such as that induced by CLP only protected from shock induced by d-galactosamine and lipopolysaccharide or by a high dose of bacteria but sensitized to a secondary bacterial infection. Such sepsis-induced enhanced susceptibility to infection was critically dependent on TNF function.
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Takei, Yoshinori, i Ronald Laskey. "Tumor Necrosis Factor α Regulates Responses to Nerve Growth Factor, Promoting Neural Cell Survival but Suppressing Differentiation of Neuroblastoma Cells". Molecular Biology of the Cell 19, nr 3 (marzec 2008): 855–64. http://dx.doi.org/10.1091/mbc.e07-06-0624.
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Although nerve growth factor (NGF) promotes survival of neurons, tumor necrosis factor α (TNF-α) contributes to cell death triggered by NGF depletion, through TNF-α receptor (TNFR) 1. In contrast to this effect, TNF-α can promote neural cell survival via TNF-α receptor TNFR2. Although these findings demonstrate pivotal roles of TNF-α and NGF in cell fate decisions, cross-talk between these signaling pathways has not been clarified. We find that NGF can induce TNF-α synthesis through the nuclear factor-κB transcription factor. This provides a new basis for examining the cross-talk between NGF and TNF-α. Inhibition of TNFR2 shows opposite effects on two downstream kinases of NGF, extracellular signal-regulated kinase (Erk) and Akt. It increases Erk activation by NGF, and this increased activation induces differentiation of neuroblastoma cell lines. Reciprocally, inhibition of TNFR2 decreases Akt activation by NGF. Consistent with an essential role of Akt in survival signaling, inhibition of TNF-α signaling decreases NGF-dependent survival of neurons from rat dorsal root ganglia. Thus, NGF and NGF-induced TNF-α cooperate to activate Akt, promoting survival of normal neural cells. However, the NGF-induced TNF-α suppresses Erk activation by NGF, blocking NGF-induced differentiation of neuroblastoma cells. TNFR2 signaling could be a novel target to modulate cell responses to NGF.
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Candela, M., S. C. Barker i L. R. Ballou. "Sphingosine synergistically stimulates tumor necrosis factor alpha-induced prostaglandin E2 production in human fibroblasts." Journal of Experimental Medicine 174, nr 6 (1.12.1991): 1363–69. http://dx.doi.org/10.1084/jem.174.6.1363.
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Sphingosine is a biologically active derivative of sphingomyelin. It affects diverse cellular functions and its mechanism(s) of action is poorly defined. Tumor necrosis factor alpha (TNF alpha) has recently been shown to rapidly induce sphingomyelin turnover, implicating this metabolic pathway in TNF alpha signal transduction. Because TNF alpha is known to induce prostaglandin E2 (PGE2) production in human fibroblasts, we tested the effect of sphingosine on TNF alpha-induced PGE2 production. We found that sphingosine enhanced TNF alpha-induced PGE2 production by as much as 18-fold over TNF alpha alone. Sphingosine appeared to stimulate TNF alpha-induced PGE2 production independent of TNF alpha-mediated interleukin 1 (IL-1) production, because anti-IL-1 antibodies and IL-1 receptor antagonist protein (IRAP) did not inhibit TNF alpha-induced PGE2 production or the stimulatory effect of sphingosine. TNF alpha stimulated PGE2 production to the same degree in normal and protein kinase C (PKC) downregulated cells in the presence and absence of sphingosine, indicating that neither TNF alpha nor sphingosine require active PKC to elicit their respective effects. The sphingosine analogues stearylamine and stearoyl-D-sphingosine had little or no effect on TNF alpha-mediated PGE2 production, supporting a specific role for sphingosine in the activation process. Short-term (1 min) exposure of cells to sphingosine dramatically increased TNF alpha-induced PGE2 production. A potential mechanism by which sphingosine could increase TNF alpha-induced PGE2 production involves enhancement of phospholipase A2 (PLA2) and/or cyclooxygenase (Cox) activity, the rate-limiting enzymes in PGE2 production. We found that both TNF alpha and sphingosine alone enhanced these enzymatic activities, and that sphingosine additively increased the effect of TNF alpha on phospholipase A2 activity. It appears that sphingosine affects TNF alpha-induced PGE2 production via a mechanism that is independent of PKC involvement, and that sphingosine may function as an endogenous second messenger capable of modulating the responsiveness of the cell to external stimuli.
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Philip, R. "Cytolysis of tumor necrosis factor (TNF)-resistant tumor targets. Differential cytotoxicity of monocytes activated by the interferons, IL-2, and TNF." Journal of Immunology 140, nr 4 (15.02.1988): 1345–49. http://dx.doi.org/10.4049/jimmunol.140.4.1345.
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Abstract Herein we demonstrate that IFN-alpha, IFN-gamma, and IL-2 can induce human peripheral blood monocyte-mediated lysis of tumor cells that are resistant to both the direct effects of TNF and to monocytes activated by TNF. Monocytes activated by TNF kill only TNF-sensitive tumor targets, whereas those activated by IFN and IL-2 can lyse both TNF-sensitive and TNF-resistant tumor targets. Monocyte cytotoxicity against TNF-sensitive lines induced by the IFN, IL-2, or TNF can be completely abrogated by the addition of anti-TNF antibodies. In contrast, anti-TNF antibodies have no effect on IFN- or IL-2-induced monocyte cytotoxicity against TNF resistant targets, confirming non-TNF-mediated lysis induced by lymphokine-activated monocytes. Neither induction of TNF receptors by IFN-gamma nor inhibition of RNA synthesis by actinomycin D increased the susceptibility of TNF-resistant tumor targets to TNF-mediated monocyte cytotoxicity. Thus, non-TNF-mediated modes of monocyte cytotoxicity are induced by IFN and IL-2, but not by TNF, indicating that different cytotoxic mechanisms are responsible for the lysis of TNF-sensitive and TNF-resistant tumor cells. In addition, these findings also suggest that TNF-sensitive lines are susceptible only to TNF-mediated killing and apparently insensitive to non-TNF-mediated monocyte cytotoxicity.
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Wilson, Michael R., Sharmila Choudhury i Masao Takata. "Pulmonary inflammation induced by high-stretch ventilation is mediated by tumor necrosis factor signaling in mice". American Journal of Physiology-Lung Cellular and Molecular Physiology 288, nr 4 (kwiecień 2005): L599—L607. http://dx.doi.org/10.1152/ajplung.00304.2004.
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Although high-stretch mechanical ventilation has been demonstrated to induce lung inflammation, the roles of soluble mediators, in particular TNF, remain controversial. We have previously shown in mice that high-stretch ventilation, in the absence of preceding lung injury, induces expression of bioactive TNF in lung lavage fluid early in the course of injury, but the biological significance of this, if any, has yet to be determined. We therefore investigated the pulmonary inflammatory response to a transient period of high-stretch ventilation in anesthetized mice lacking TNF receptors and mice treated with anti-TNF antibodies. A standardized stretch-induced lung injury (assessed by lung mechanics, blood gases, and lavage protein content), followed by noninjurious low-stretch ventilation for 3 h, produced significant alveolar neutrophil infiltration in wild-type mice. However, neutrophil recruitment was substantially attenuated in TNF receptor double knockout mice and in wild-type mice treated with intratracheal anti-TNF antibody. This attenuation was not associated with decreased concentrations of neutrophil attractant CXC chemokines (macrophage inflammatory protein-2 and keratinocyte-derived chemokine) in lavage fluid. In contrast to intratracheal antibody, intravenous anti-TNF antibody did not reduce neutrophil infiltration, suggesting that the role of TNF signaling is localized within the alveolar space and does not require decompartmentalization of TNF into the circulation. These findings provide the first direct evidence that pulmonary inflammation induced by high-stretch ventilation without underlying lung injury possesses a significant TNF-dependent component. The results suggest a potential for regional anti-TNF treatment in attenuating stretch-induced pulmonary inflammation.
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Zhuang, Lihua, Binghe Wang, Gayle A. Shinder, Gulnar M. Shivji, Tak W. Mak i Daniel N. Sauder. "TNF Receptor p55 Plays a Pivotal Role in Murine Keratinocyte Apoptosis Induced by Ultraviolet B Irradiation". Journal of Immunology 162, nr 3 (1.02.1999): 1440–47. http://dx.doi.org/10.4049/jimmunol.162.3.1440.
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Abstract Excess exposure of skin to ultraviolet B (UVB) results in the appearance of so-called sunburn cells. Although it has been demonstrated that sunburn cells represent apoptotic keratinocytes, the molecular mechanisms for UVB-induced apoptosis in keratinocytes have not been fully elucidated. The cytokine, TNF-α, has been shown to induce apoptosis in a variety of cell types. Since UVB induces keratinocytes to release TNF-α, we hypothesized that TNF-α is involved in UVB-induced apoptosis in keratinocytes. In order to confirm this hypothesis and to further delineate which type of TNF receptor signaling mediates the apoptosis pathway, we performed both in vivo and in vitro experiments using gene-targeted knockout mice lacking either the TNF p55 receptor or the TNF p75 receptor. In the in vivo study, wild-type and mutant mice were exposed to UVB, and apoptotic keratinocytes were detected by examining DNA fragmentation using in situ nick-end labeling. For the in vitro experiments, keratinocytes derived from the wild-type and mutant mice were irradiated with UVB, and the degree of apoptosis was determined by flow cytometry, nick-end labeling of DNA, and a DNA ladder assay. Both in vivo and in vitro studies demonstrated that the deletion of TNF receptor p55 could suppress UVB-induced apoptosis in keratinocytes. Our observations support the notion that TNF-α is involved in UVB-induced keratinocyte apoptosis, and demonstrate that p55 receptor signaling plays a pivotal role in this event.
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Tang, Fangming, Guilin Tang, Jialing Xiang, Qing Dai, Marsha R. Rosner i Anning Lin. "The Absence of NF-κB-Mediated Inhibition of c-Jun N-Terminal Kinase Activation Contributes to Tumor Necrosis Factor Alpha-Induced Apoptosis". Molecular and Cellular Biology 22, nr 24 (15.12.2002): 8571–79. http://dx.doi.org/10.1128/mcb.22.24.8571-8579.2002.
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ABSTRACT The proinflammatory cytokine tumor necrosis factor alpha (TNF-α) regulates immune responses, inflammation, and programmed cell death (apoptosis). TNF-α exerts its biological activities by activating multiple signaling pathways, including IκB kinase (IKK), c-Jun N-terminal protein kinase (JNK), and caspases. IKK activation inhibits apoptosis through the transcription factor NF-κB, whose target genes include those that encode inhibitors of both caspases and JNK. Despite activation of the antiapoptotic IKK/NF-κB pathway, TNF-α is able to induce apoptosis in cells sensitive to it, such as human breast carcinoma MCF-7 and mouse fibroblast LM cells. The molecular mechanism underlying TNF-α-induced apoptosis is incompletely understood. Here we report that in TNF-α-sensitive cells activation of the IKK/NF-κB pathway fails to block TNF-α-induced apoptosis, although its inactivation still promotes TNF-α-induced apoptosis. Interestingly, TNF-α-induced apoptosis is suppressed by inhibition of the JNK pathway but promoted by its activation. Furthermore, activation of JNK by TNF-α was transient in TNF-α-insensitive cells but prolonged in sensitive cells. Conversion of JNK activation from prolonged to transient suppressed TNF-α-induced apoptosis. Thus, absence of NF-κB-mediated inhibition of JNK activation contributes to TNF-α-induced apoptosis.
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Moriwaki, Chihiro, Riho Tanigaki, Yasunobu Miyake, Nghia Trong Vo, Mai Thanh Thi Nguyen, Nhan Trung Nguyen, Truong Nhat Van Do, Hai Xuan Nguyen i Takao Kataoka. "Isopanduratin A Inhibits Tumor Necrosis Factor (TNF)-α-Induced Nuclear Factor κB Signaling Pathway by Promoting Extracellular Signal-Regulated Kinase-Dependent Ectodomain Shedding of TNF Receptor 1 in Human Lung Adenocarcinoma A549 Cells". BioChem 1, nr 3 (1.11.2021): 174–89. http://dx.doi.org/10.3390/biochem1030014.
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Tumor necrosis factor α (TNF-α) induces the nuclear factor κB (NF-κB) signaling pathway via TNF receptor 1 (TNF-R1). We recently reported that isopanduratin A inhibited the TNF-α-induced NF-κB signaling pathway in human lung adenocarcinoma A549 cells. In the present study, we found that isopanduratin A did not inhibit the interleukin-1α-induced NF-κB signaling pathway in A549 cells. Isopanduratin A down-regulated the expression of TNF-R1 in these cells. We also revealed that isopanduratin A down-regulated the cell surface expression of TNF-R1 by promoting the cleavage of TNF-R1 into its soluble forms. TAPI-2, an inhibitor of TNF-α-converting enzyme, suppressed the inhibitory activity of isopanduratin A against the TNF-α-induced activation of NF-κB. The mitogen-activated protein (MAP) kinase/extracellular signal-regulated kinase (ERK) kinase inhibitor U0126, but not the p38 MAP kinase inhibitor SB203580, blocked the ectodomain shedding of TNF-R1 induced by isopanduratin A. Consistent with this result, isopanduratin A induced the rapid phosphorylation of ERK, but not p38 MAP kinase. Isopanduratin A also promoted the phosphorylation of eukaryotic initiation factor 2α (eIF2α). The present results indicate that isopanduratin A inhibits TNF-α-induced NF-κB signaling pathway by promoting ERK-dependent ectodomain shedding of cell surface TNF-R1, and also decreases cellular TNF-R1 levels through the phosphorylation of eIF2α in A549 cells.
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Corbett, J. A., i M. L. McDaniel. "Intraislet release of interleukin 1 inhibits beta cell function by inducing beta cell expression of inducible nitric oxide synthase." Journal of Experimental Medicine 181, nr 2 (1.02.1995): 559–68. http://dx.doi.org/10.1084/jem.181.2.559.
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Cytokines, released in and around pancreatic islets during insulitis, have been proposed to participate in beta-cell destruction associated with autoimmune diabetes. In this study we have evaluated the hypothesis that local release of the cytokine interleukin 1 (IL-1) by nonendocrine cells of the islet induce the expression of inducible nitric oxide synthase (iNOS) by beta cells which results in the inhibition of beta cell function. Treatment of rat islets with a combination of tumor necrosis factor (TNF) and lipopolysaccharide (LPS), conditions known to activate macrophages, stimulate the expression of iNOS and the formation of nitrite. Although TNF+LPS induce iNOS expression and inhibit insulin secretion by intact islets, this combination does not induce the expression of iNOS by beta or alpha cells purified by fluorescence activated cell sorting (Facs). In contrast, IL-1 beta induces the expression of iNOS and also inhibits insulin secretion by both intact islets and Facs-purified beta cells, whereas TNF+LPS have no inhibitory effects on insulin secretion by purified beta cells. Evidence suggests that TNF+LPS inhibit insulin secretion from islets by stimulating the release of IL-1 which subsequently induces the expression of iNOS by beta cells. The IL-1 receptor antagonist protein completely prevents TNF+LPS-induced inhibition of insulin secretion and attenuates nitrite formation from islets, and neutralization of IL-1 with antisera specific for IL-1 alpha and IL-1 beta attenuates TNF+LPS-induced nitrite formation by islets. Immunohistochemical localization of iNOS and insulin confirm that TNF+LPS induce the expression of iNOS by islet beta cells, and that a small percentage of noninsulin-containing cells also express iNOS. Local release of IL-1 within islets appears to be required for TNF+LPS-induced inhibition of insulin secretion because TNF+LPS do not stimulate nitrite formation from islets physically separated into individual cells. These findings provide the first evidence that a limited number of nonendocrine cells can release sufficient quantities of IL-1 in islets to induce iNOS expression and inhibit the function of the beta cell, which is selectively destroyed during the development of autoimmune diabetes.
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Baer, Mark, Allan Dillner, Richard C. Schwartz, Constance Sedon, Sergei Nedospasov i Peter F. Johnson. "Tumor Necrosis Factor Alpha Transcription in Macrophages Is Attenuated by an Autocrine Factor That Preferentially Induces NF-κB p50". Molecular and Cellular Biology 18, nr 10 (1.10.1998): 5678–89. http://dx.doi.org/10.1128/mcb.18.10.5678.
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ABSTRACT Macrophages are a major source of proinflammatory cytokines such as tumor necrosis factor alpha (TNF-α), which are expressed during conditions of inflammation, infection, or injury. We identified an activity secreted by a macrophage tumor cell line that negatively regulates bacterial lipopolysaccharide (LPS)-induced expression of TNF-α. This activity, termed TNF-α-inhibiting factor (TIF), suppressed the induction of TNF-α expression in macrophages, whereas induction of three other proinflammatory cytokines (interleukin-1β [IL-1β], IL-6, and monocyte chemoattractant protein 1) was accelerated or enhanced. A similar or identical inhibitory activity was secreted by IC-21 macrophages following LPS stimulation. Inhibition of TNF-α expression by macrophage conditioned medium was associated with selective induction of the NF-κB p50 subunit. Hyperinduction of p50 occurred with delayed kinetics in LPS-stimulated macrophages but not in fibroblasts. Overexpression of p50 blocked LPS-induced transcription from a TNF-α promoter reporter construct, showing that this transcription factor is an inhibitor of the TNF-α gene. Repression of the TNF-α promoter by TIF required a distal region that includes three NF-κB binding sites with preferential affinity for p50 homodimers. Thus, the selective repression of the TNF-α promoter by TIF may be explained by the specific binding of inhibitory p50 homodimers. We propose that TIF serves as a negative autocrine signal to attenuate TNF-α expression in activated macrophages. TIF is distinct from the known TNF-α-inhibiting factors IL-4, IL-10, and transforming growth factor β and may represent a novel cytokine.
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Xiao, Kan, Shuting Cao, Lefei Jiao, Zehe Song, Jianjun Lu i Caihong Hu. "TGF-β1 protects intestinal integrity and influences Smads and MAPK signal pathways in IPEC-J2 after TNF-α challenge". Innate Immunity 23, nr 3 (31.01.2017): 276–84. http://dx.doi.org/10.1177/1753425917690815.
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The aim of this study was to investigate the protective effects of TGF-β1 on intestinal epithelial barrier, as well as canonical Smad and MAPK signal pathways involved in these protection processes by a IPEC-J2 model stimulated with TNF-α. IPEC-J2 monolayers were treated without or with TNF-α in the absence or presence of TGF-β1. The results showed that TGF-β1 pretreatment ameliorated TNF-α-induced intestinal epithelial barrier disturbances as indicated by decrease of transepithelial electrical resistance (TER) and increase of paracellular permeability. TGF-β1 also dramatically alleviated TNF-α-induced alteration of TJ proteins ZO-1 and occludin. Moreover, TGF-β1 pretreatment increased TβRII protein expression in IPEC-J2 monolayers challenged with TNF-α. In addition, a significant increase of Smad4 and Smad7 mRNA was also observed in the TGF-β1 pretreatment after TNF-α challenge compared with the control group. Furthermore, TGF-β1 pretreatment enhanced smad2 protein activation. These results indicated that the canonical Smad signaling pathway was activated by TGF-β1 pretreatment. Finally, TGF-β1 pretreatment decreased the ratios of the phosphorylated to total JNK and p38 (p-JNK/JNK and p-p38/p38) and increased the ratio of ERK (p-ERK/ERK). Anti-TGF-β1 Abs reduced these TGF-β1 effects. These results indicated that TGF-β1 protects intestinal integrity and influences Smad and MAPK signal pathways in IPEC-J2 after TNF-α challenge.
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Chaby, R., T. Pedron, P. L. Stütz i R. Girard. "Lipopolysaccharide and tumor necrosis factor-alpha induce lipopolysaccharide receptor expression on bone marrow cells by different mechanisms." Journal of Immunology 151, nr 9 (1.11.1993): 4476–85. http://dx.doi.org/10.4049/jimmunol.151.9.4476.
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Abstract Two cell types, monocytes/macrophages and neutrophilic granulocytes, play a prominent role in the pathogenic effects of endotoxins during Gram-negative infections. We previously established that nanomolar concentrations of LPS induce the expression of new specific LPS-binding sites (LpsR) in bone marrow granulocytes of LPS-responsive mice. To examine this induction process further, we asked whether it, like other LPS activities, can be mediated by TNF-alpha. We report that exogenous rTNF-alpha can induce LpsR expression in bone marrow cells (BMC) from both LPS-responsive (C3H/HeOU) and LPS-hyporesponsive (C3H/HeJ) mice. In BMC, LPS elicited a down-regulation of the TNF-alpha receptors (TNF-R) without direct binding to TNF-R. On the other hand, taxol, a microtubule stabilizer that has shown LPS mimetic activity in macrophages, was unable to elicit LpsR expression or induce TNF-R down-regulation in BMC. Thus, unlike the LPS-signaling receptor of macrophages, that of BMC is apparently not functionally associated with microtubules. The LPS-induced expression of LpsR was inhibited only partially with an anti-TNF-alpha serum, and with dexamethasone, suggesting that an autocrine activity of endogenous TNF-alpha cannot alone account for the LPS effect. Comparative analyses also indicated that dexamethasone inhibited the LPS-induced increase of LpsR, but enhanced the number of TNF-induced LpsR+ BMC. Furthermore, the synthetic lipid PPDm2 (a 1,4-bisphosphorylated and N,N-diacylated derivative of 2,3-diamino-2,3-dideoxy-D-glucose) inhibited LPS-induced, but not TNF-induced, expression of LpsR. These data show that in BMC, LPS and TNF-alpha induce LpsR expression by different mechanisms.
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Zhu, Xiaohong, Ziwei Hu, Tian Yu, Hao Hu, Yunshi Zhao, Chenyang Li, Qinchang Zhu i in. "The Antiviral Effects of Jasminin via Endogenous TNF-α and the Underlying TNF-α-Inducing Action". Molecules 27, nr 5 (28.02.2022): 1598. http://dx.doi.org/10.3390/molecules27051598.
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Previous studies have reported that recombinant tumor necrosis factor (TNF)-α has powerful antiviral activity but severe systematic side effects. Jasminin is a common bioactive component found in Chinese herbal medicine beverage “Jasmine Tea”. Here, we report that jasminin-induced endogenous TNF-α showed antiviral activity in vitro. The underlying TNF-α-inducing action of jasminin was also investigated in RAW264.7 cells. The level of endogenous TNF-α stimulated by jasminin was first analyzed by an enzyme-linked immunosorbent assay (ELISA) from the cell culture supernatant of RAW264.7 cells. The supernatants were then collected to investigate the potential antiviral effect against herpes simplex virus 1 (HSV-1). The antiviral effects of jasminin alone or its supernatants were evaluated by a plaque reduction assay. The potential activation of the PI3K–Akt pathway, three main mitogen-activated protein kinases (MAPKs), and nuclear factor (NF)–κB signaling pathways that induce TNF-α production were also investigated. Jasminin induces TNF-α protein expression in RAW264.7 cells without additional stimuli 10-fold more than the control. No significant up-expression of type I, II, and III interferons; interleukins 2 and 10; nor TNF-β were observed by the jasminin stimuli. The supernatants, containing jasminin-induced-TNF-α, showed antiviral activity against HSV-1. The jasminin-stimulated cells caused the simultaneous activation of the Akt, MAPKs, and NF–κB signal pathways. Furthermore, the pretreatment of the cells with the Akt, MAPKs, and NF–κB inhibitors effectively suppressed jasminin-induced TNF-α production. Our research provides evidence that endogenous TNF-α can be used as a strategy to encounter viral infections. Additionally, the Akt, MAPKs, and NF–κB signaling pathways are involved in the TNF-α synthesis that induced by jasminin.
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Takahashi, Satoshi, Levente Kapás, Jidong Fang i James M. Krueger. "Somnogenic relationships between tumor necrosis factor and interleukin-1". American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 276, nr 4 (1.04.1999): R1132—R1140. http://dx.doi.org/10.1152/ajpregu.1999.276.4.r1132.
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Both tumor necrosis factor (TNF) and interleukin (IL)-1 are somnogenic cytokines. They also induce each other’s production and both induce nuclear factor kappa B activation, which in turn enhances IL-1 and TNF transcription. We hypothesized that TNF and IL-1 could influence each other’s somnogenic actions. To test this hypothesis, we determined the effects of blocking both endogenous TNF and IL-1 on spontaneous sleep and on sleep rebound after sleep deprivation in rabbits. Furthermore, the effects of inhibition of TNF on IL-1-induced sleep and the effects of blocking IL-1 on TNF-induced sleep were determined. A TNF receptor fragment (TNFRF), as a TNF inhibitor, and an IL-1 receptor fragment (IL-1RF), as an IL-1 inhibitor, were used. Intracerebroventricular injection of a combination of the TNFRF plus the IL-1RF significantly reduced spontaneous non-rapid eye movement sleep by 87 min over a 22-h recording period. Pretreatment of rabbits with the combination of TNFRF and IL-1RF also significantly attenuated sleep rebound after sleep deprivation. Furthermore, the TNFRF significantly attenuated IL-1-induced sleep but not fever. Finally, the IL-1RF blocked TNF-induced sleep responses but not fever. Results indicate that TNF and IL-1 cooperate to regulate physiological sleep.
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Jacobsen, F. W., O. P. Veiby, T. Stokke i S. E. Jacobsen. "TNF-alpha bidirectionally modulates the viability of primitive murine hematopoietic progenitor cells in vitro." Journal of Immunology 157, nr 3 (1.08.1996): 1193–99. http://dx.doi.org/10.4049/jimmunol.157.3.1193.
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Abstract It is well established that TNF-alpha can induce apoptosis in many normal and transformed cell types. The effects of TNF-alpha on cytokine-induced proliferation and differentiation of normal hematopoietic progenitors have been characterized extensively, whereas little is known about how TNF-alpha can affect their viability. The present studies suggest, based on experiments using delayed addition of growth-promoting cytokines as well direct viability assays, that TNF-alpha bidirectionally affects the survival of individually cultured primitive Lin- Sca-1+ hematopoietic progenitors, in that stem cell factor (SCF)-, granulocyte-CSF-, IL-6-, and IL-11-induced survival is potently counteracted by TNF-alpha (42-86%), whereas TNF-alpha synergistically enhances IL-1alpha-induced survival up to threefold. The bidirectional effects of TNF-alpha on hematopoietic growth factor-induced survival of hematopoietic progenitors were reflected in that TNF-alpha enhanced apoptosis of Lin- Sca-1+ cells when combined with SCF, whereas TNF-alpha synergistically suppressed apoptosis in response to IL-1alpha.
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Idell, S., C. Zwieb, J. Boggaram, D. Holiday, A. R. Johnson i G. Raghu. "Mechanisms of fibrin formation and lysis by human lung fibroblasts: influence of TGF-beta and TNF-alpha". American Journal of Physiology-Lung Cellular and Molecular Physiology 263, nr 4 (1.10.1992): L487—L494. http://dx.doi.org/10.1152/ajplung.1992.263.4.l487.
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Fibrin gels form within the alveolar and interstitial compartments of the injured lung, and fibroblasts invade and facilitate organization of these transitional gels. We studied the effects of transforming growth factor-beta (TGF-beta) and tumor necrosis factor-alpha (TNF-alpha) on fibrinolytic and procoagulant activities of human lung fibroblasts (HLF) to determine their capacity to regulate pulmonary fibrin deposition. Fibrinolytic activity of cell lysates and media (n = 6 HLF cultures) were uniformly depressed by TGF-beta or TNF-alpha. In dose and time-course studies, HLF plasminogen activator inhibitor-1 (PAI-1) was increased by TGF-beta, whereas TNF-alpha induced release of PAI-1 into the media. HLF and media urokinase concentrations were depressed by TGF-beta, whereas urokinase was unchanged or increased by TNF-alpha. Tissue plasminogen activator was mainly cell associated and unchanged by TGF-beta or TNF-alpha. HLF antiplasmin activity was not detected. Plasma recalcification times of HLF media were decreased by TNF-alpha but unchanged by TGF-beta. These studies suggest that TGF-beta and TNF-alpha impair the ability of HLF to degrade fibrin by disturbing the balance of HLF plasminogen activators and PAI and that these cytokines concurrently leave unchanged or increase the capacity of HLF to initiate fibrin formation. Cytokines likely to occur in the injured lung induce abnormalities of fibrinolysis in HLF from adults; such abnormalities favor extravascular fibrin deposition, a characteristic feature of alveolitis.
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Feingold, K. R., S. Adi, I. Staprans, A. H. Moser, R. Neese, J. A. Verdier, W. Doerrler i C. Grunfeld. "Diet affects the mechanisms by which TNF stimulates hepatic triglyceride production". American Journal of Physiology-Endocrinology and Metabolism 259, nr 2 (1.08.1990): E177—E184. http://dx.doi.org/10.1152/ajpendo.1990.259.2.e177.
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Tumor necrosis factor (TNF) induces hyperlipidemia in rodents by increasing hepatic triglyceride production. We now explore the mechanism of this increase. TNF does not increase phosphatidate phosphohydrolase, glycerolphosphate acyltransferase, or diacylglycerol acyltransferase, which are enzymes of triglyceride synthesis. Rather, TNF increases triglyceride production by providing increased fatty acids (FA) as substrate. In chow-fed rats, TNF increases plasma free fatty acids (FFA). The antilipolytic drug, phenylisopropyl adenosine (PIA), prevents the TNF-induced increase in plasma FFA and, most importantly, inhibits the TNF-induced increase in plasma triglycerides. Thus increased lipolysis with delivery of FA to liver contributes to TNF-induced hyperlipidemia in chow-fed animals. In contrast, in rats fed a high-sucrose diet, TNF causes hyperlipidemia without increasing plasma FFA, and PIA has no effect on TNF-induced increases in plasma triglycerides. However, in sucrose-fed rats, TNF markedly stimulates hepatic de novo FA synthesis, which provides FA. This diet determines the mechanism by which TNF stimulates hepatic triglyceride production. The use of multiple mechanisms to increase plasma triglycerides suggests that this TNF action plays an important role in the response to infection or inflammation.
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Nawroth, P., D. Handley, G. Matsueda, R. De Waal, H. Gerlach, D. Blohm i D. Stern. "Tumor necrosis factor/cachectin-induced intravascular fibrin formation in meth A fibrosarcomas." Journal of Experimental Medicine 168, nr 2 (1.08.1988): 637–47. http://dx.doi.org/10.1084/jem.168.2.637.
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Recent studies have indicated that TNF can promote activation of the coagulation mechanism by modulating coagulant properties of endothelial cells. In this report, we demonstrate that infusion of low concentrations of TNF (3 micrograms/animal) into mice bearing meth A fibrosarcomas leads to localized fibrin deposition with formation of occlusive intravascular thrombi in close association with the endothelial cell surface. Studies with 125I-fibrinogen showed tenfold enhanced accumulation of radioactivity in tumor within 2 h after TNF infusion. Western blots of tumor extracts subjected to SDS-PAGE and visualized with a fibrin-specific mAb indicated that fibrin forms in the tumor after the TNF infusion. Electron microscopic studies demonstrated fibrin strands, based on the characteristic 21-nm periodicity, which appeared to be adherent to the endothelial cell surface. Further ultrastructural studies indicated that fibrin formation, first evident within 30 min of the TNF infusion, led to occlusive thrombi limited to the tumor vascular bed (i.e., not in the normal mouse vasculature) within 2 h and was associated with an 80% reduction in tumor perfusion based on studies with Evans blue. In view of previous work concerning TNF induction of endothelial cell procoagulant activity, the hypothesis that tumor cell products prime the response of endothelium to this cytokine was tested. Supernatants of cultured meth A fibrosarcomas obtained serum-free conditions, which had no intrinsic procoagulant activity, considerably enhanced tissue factor induction in endothelium in response to submaximal concentrations of TNF. The factor(s) in the tumor-conditioned medium appeared to be distinct from IL-1, fibroblast growth factor, IFN-gamma, TNF, endotoxin, TGF-alpha, and TGF-beta. These studies delineate a novel model of localized clot formation in which thrombosis is initiated by a pathophysiologic mediator, TNF, and provides an opportunity to examine mechanisms in the microenvironment directing clot formation to the tumor vascular bed.
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Bradham, Cynthia A., Jörg Plümpe, Michael P. Manns, David A. Brenner i Christian Trautwein. "I. TNF-induced liver injury". American Journal of Physiology-Gastrointestinal and Liver Physiology 275, nr 3 (1.09.1998): G387—G392. http://dx.doi.org/10.1152/ajpgi.1998.275.3.g387.
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Tumor necrosis factor-α (TNF-α) functions as a two-edged sword in the liver. TNF-α is required for normal hepatocyte proliferation during liver regeneration. It functions both as a comitogen and to induce the transcription factor nuclear factor-κB, which has antiapoptotic effects. On the other hand, TNF-α is the mediator of hepatotoxicity in many animal models, including those involving the toxins concanavalin A and lipopolysaccharide. TNF-α has also been implicated as an important pathogenic mediator in patients with alcoholic liver disease and viral hepatitis.
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Wagner, Elizabeth M. "TNF-α induced bronchial vasoconstriction". American Journal of Physiology-Heart and Circulatory Physiology 279, nr 3 (1.09.2000): H946—H951. http://dx.doi.org/10.1152/ajpheart.2000.279.3.h946.
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The pro-inflammatory characteristics of tumor necrosis factor-α (TNF-α) have been extensively characterized in in vitro systems. Furthermore, this cytokine has been shown to play a pivotal role in airways inflammation in asthma. Since the airway vasculature also performs an essential function in inflammatory cell transit to the airways, experiments were performed to determine the effects of TNF-α on bronchial vascular resistance (BVR). In anesthetized, ventilated sheep, the bronchial artery (BA) was cannulated and perfused with autologous blood. BVR was defined as inflow pressure/flow and averaged 6.3 ± 0.2 mmHg · ml−1 · min−1 (±SE) for the 25 sheep studied. Recombinant human TNF-α (10 μg for 20 or 40 min) infused directly into the BA resulted in a significant decrease in BVR to 87% of baseline ( P < 0.05). This vasodilation was followed by a reversal of tone by 120 min and a sustained increase in BVR to 126% of baseline ( P < 0.05). Since others have shown TNF-α caused coronary vasoconstriction through endothelial release of endothelin-1 (ET-1), an ET-1 antagonist was used to block bronchial vasoconstriction. BQ-123, a selective ETA receptor antagonist, was delivered to the bronchial vasculature prior to TNF-α challenge. Attenuation of bronchial vasoconstriction was observed at 120 min ( P < 0.03). Thus TNF-α causes bronchial vasoconstriction by the secondary release of ET-1. Although TNF-α exerts pro-inflammatory actions on most cells of the airways, vasoactive properties of this cytokine likely further contribute to the inflammatory status of the airways.
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Borman, Meredith A., Stefan Urbanski i Mark G. Swain. "Anti-TNF-induced autoimmune hepatitis". Journal of Hepatology 61, nr 1 (lipiec 2014): 169–70. http://dx.doi.org/10.1016/j.jhep.2014.01.032.
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