UNIPROT:P05231 - FACTA Search

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Query: UNIPROT:P05231 (interleukin-6)
23,907 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HepG2 cells were cultured for 7 days in serum-free medium in the presence of interleukin-6 (IL-6), retinoic acid (RA) or dexamethasone (DX), and some plasma proteins secreted to the media were determined by electroimmunoassay whereas the contents of specific mRNAs in the cells was evaluated by Northern blot hybridization. Interleukin-6 maximally stimulated synthesis of alpha-1-antichymotrypsin between days 1 and 3 whereas the response of fibrinogen was delayed to days 3 to 7. Retinoic acid increased the effect of IL-6 on alpha-1-antichymotrypsin (ACT) and fibrinogen (FBG) on the level of both proteins and mRNAs. Synthesis of albumin was slightly inhibited by IL-6 and RA, and synthesis of transferrin was increased by RA but not by IL-6. Dexamethasone had small enhancing effect on the action of IL-6. These results suggest that long-term HepG2 cultures may provide an experimental model for liver acute phase response during chronic inflammation.
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PMID:Long-term culture of HepG2 hepatoma cells as a model for liver acute phase response during chronic inflammation. Effects of interleukin-6, dexamethasone and retinoic acid. 769 40

alpha 1-Antitrypsin (alpha 1-AT) and alpha 1-antichymotrypsin (alpha 1-ACHY) are closely related protease inhibitors, synthesized primarily by the liver, which play major roles in modulation of the inflammatory response. Previously, we had shown that MCF-7 human breast cancer cells were able to synthesize active alpha 1-AT and alpha 1-ACHY and that the synthesis of both inhibitors varied among different MCF-7 sublines. We now show that when MCF-7(ML) cells (a subline synthesizing low levels of alpha 1-AT) are grown in soft agar in medium depleted of its trypsin inhibitory capacity (i.e. alpha 1-AT-free), addition of alpha 1-AT (50 micrograms/ml) significantly reduces colony formation in both the presence and absence of estradiol (34% and 44%, respectively). Under these conditions, incubation with 10(-7) M estradiol alone increased colony formation 2- to 3-fold. Colony formation was also significantly reduced by serum leukocyte protease inhibitor, which, like alpha 1-AT, is a potent inhibitor of elastase-like enzymes. We also found that a variety of inflammatory mediators, cytokines, and steroid hormones are able to stimulate synthesis of alpha 1-AT and alpha 1-ACHY by MCF-7 cells. Stimulation by interleukin-6 (IL-6; 200 U/ml), epidermal growth factor (4 nM), and estradiol (10(-7) M) was 2- to 3-fold, whereas stimulations by tetradecanoylphorbol-13-acetate (TPA; 80 nM) and IL-1 (10 U/ml) were 2- to 5-fold and 5- to 10-fold, respectively. In each instance, protein synthesis, monitored by immunoprecipitation of 35S-labeled proteins followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and steady state mRNA levels, monitored by Northern blot analysis with specific cDNA probes, increased to the same extent. Consistent with their ability to stimulate alpha 1-AT synthesis, TPA and IL-1 reduced colony formation in the absence of estradiol by 65% and 63%, respectively. In addition, the effects of both TPA and IL-1 could be reversed by antibody to alpha 1-AT. These results suggest that local synthesis of alpha 1-AT and possibly other protease inhibitors may be important in regulating the tumorigenic potential of MCF-7 breast cancer cells.
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PMID:alpha 1-Antitrypsin- and anchorage-independent growth of MCF-7 breast cancer cells. 836 78

Corticosteroid-binding globulin (CBG) belongs to the superfamily of serine proteinase inhibitors which include alpha 1-antitrypsin, alpha 1-antichymotrypsin, and T4-binding globulin. Interleukin-6 (IL-6), the main mediator of the acute phase phenomenon, increases alpha 1-antitrypsin and alpha 1-antichymotrypsin synthesis and decreases T4-binding globulin synthesis by human hepatoblastoma-derived (Hep G2) cells. This effect is predominantly at a transcriptional level. When Hep G2 cells were exposed to different concentrations of IL-6 for variable time intervals, IL-6 caused a dose- and time-dependent decrease in the amount of [35S]methionine-labeled CBG immunoprecipitated in the culture medium. This effect could be greatly reduced by preincubation of IL-6 with its neutralizing antibody and reversed by removing the cytokine from the culture medium. The secretion rate of CBG was not affected by cell exposure to IL-6. CBG mRNA steady state levels were reduced; changes in mRNA were quantitatively similar to changes in secreted protein. Nuclear run-off assays failed to show a change in the rate of transcription of the CBG gene. These data indicate that IL-6 diminishes CBG synthesis by Hep G2 cells acting at a posttranscriptional level, presumably through a reduced stability of mRNA. In view of the role of IL-6 in the inflammatory process and other acute phase phenomena, these data suggest that its effects on CBG synthesis might influence the bioavailability of cortisol indirectly and play a role in regulating the homeostatic process during these conditions.
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PMID:Interleukin-6 inhibits corticosteroid-binding globulin synthesis by human hepatoblastoma-derived (Hep G2) cells. 839 24

The soluble human interleukin-6 receptor (shIL6R) was purified from human plasma. In a single immunoaffinity purification step a 140000-fold enrichment with a yield of 95% was achieved. A subsequent IL-6 affinity chromatography resulted in a homogeneous receptor preparation but only in a yield of less than 5%. The biological activity of the soluble receptor was clearly demonstrated by its ability to induce the synthesis of the acute-phase protein 1-antichymotrypsin in HepG2 cells stably transfected with IL-6. Upon gel filtration, the native shIL6R showed an apparent molecular mass of 93 kDa. Analysis by SDS/PAGE revealed an apparent molecular mass of 65 kDa for the soluble receptor. Deglycosylation with peptide N-glycosidase F led to a shift in molecular mass from 65 kDa to 45 kDa. It has previously been shown that the shIL6R can be generated by shedding the membrane-bound form or by expression of an alternatively spliced mRNA. Here we show that the shIL6R isolated from human plasma is recognized by an affinity-purified peptide antibody raised against an amino acid sequence unique for the alternatively spliced isoform. Thus, the shIL6R isoform generated through alternative splicing which has been previously detected in supernatants of cultured cell lines is also an in vivo product circulating in human plasma.
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PMID:Purification and characterization of the soluble interleukin-6 receptor from human plasma and identification of an isoform generated through alternative splicing. 866 2

Our study addressed the role of the human hepatocyte growth factor (HGF), a potent mitogen for mature rat and human hepatocytes, in the regulation of specific hepatic genes. The experimental evidence obtained in primary cultured human hepatocytes indicates that HGF regulates the synthesis of plasma proteins in a dose-response fashion. It stimulates the synthesis of the negative acute-phase proteins albumin, transferrin, and fibronectin, decreases that of alpha1-antichymotrypsin (ACT) and haptoglobin, and stimulates that of alpha2-macroglobulin (AMG), which in man is insensitive to inflammatory mediators. HGF had no effect on C-reactive protein (CRP) synthesis. These effects differ from those elicited by interleukin-6 (IL-6). The effects of HGF on fibrinogen and alpha1-antitrypsin were, however, similar to those induced by IL-6. The effects of HGF were also observed at the messenger RNA (mRNA) level. Time-course induction experiments showed that the effects of HGF on protein synthesis were delayed by about 48 to 72 hours, in contrast with the 12-hour lag found after IL-6 stimulation. Although the presence of glucocorticoids was not absolutely necessary for HGF to affect plasma protein synthesis, it moderately extended the effects. In pulse-chase experiments, it was found that the action of HGF was not due to an alteration of the rate of secretion of the proteins. The effects of HGF on the synthesis of albumin, transferrin, fibronectin, alpha1-antichymotrypsin, and haptoglobin could be counteracted by the simultaneous presence of IL-6 in the incubation media. A clear additive effect was observed only in the case of fibrinogen. No interaction was observed in the cases of CRP and AMG. The results of this study indicate that the effects of HGF on human hepatocytes may not simply be limited to its mitogenic activity, but that it also regulates hepatic-specific genes and antagonizes, in part, the action of IL-6.
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PMID:The hepatocyte growth factor regulates the synthesis of acute-phase proteins in human hepatocytes: divergent effect on interleukin-6-stimulated genes. 867 50

In recent years many studies have indicated an involvement of inflammatory mechanisms in Alzheimer's disease (AD). Acute-phase proteins such as alpha 1-antichymotrypsin and c-reactive protein, elements of the complement system, and activated microglial and astroglial cells are consistently found in brains of AD patients. Most importantly, also cytokines such as interleukin-6 (IL-6) have been detected in the cortices of AD patients, indicating a local activation of components of the unspecific inflammatory system. Up to now it has remained unclear whether inflammatory mechanisms represent a primary event or only an unspecific reaction to brain tissue damage. Therefore, we investigated whether IL-6 immunoreactivity could be found in plaques prior to the onset of neuritic changes, or whether the presence of this cytokine is restricted to later stages of plaque pathology. We confirmed our previous observation that IL-6 is detectable in a significant proportion of plaques in the brains of demented patients. In AD patients IL-6 was found in diffuse plaques in a significant higher ratio as would have been expected from a random distribution of IL-6 among all plaque types. This observation suggests that IL-6 may precede neuritic changes, and that immunological mechanism may be involved both in the transformation from diffuse to neuritic plaques in AD and in the development of dementia.
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PMID:Inflammatory mechanisms in Alzheimer's disease. 873 96

Cytokines such as interleukin-1 (IL-1) and interleukin-6 (IL-6) have previously been shown to participate in neurodegenerative processes including Alzheimer's disease. However, the molecular consequences of increased cytokine expression in the brain remain largely unknown. We have studied the effects of IL-1, IL-6 and TNF alpha on the expression of the acute-phase protein alpha 1-antichymotrypsin (ACT) in human astrocytoma cell lines. Both IL-1 and TNF alpha, but not IL-6, were able to induce ACT gene transcription and protein synthesis. The synthetic glucocorticoid dexamethasone enhanced cytokine-induced ACT mRNA expression and protein synthesis. We conclude that IL-1-induced expression of ACT may be part of the inflammatory response in the brain and may be involved in the pathology of Alzheimer's disease.
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PMID:IL-1 beta and TNF alpha, but not IL-6, induce alpha 1-antichymotrypsin expression in the human astrocytoma cell line U373 MG. 874 37

Because neutrophil proteinases such as elastase and cathepsin G are considered to play a major role in inflammatory tissue damage, the microcirculatory effect of the serine proteinase inhibitor (serpin) Lex032 after ischemia/reperfusion (I/R)-induced pancreatitis was investigated. Lex032 inhibits these proteinases by recombinant combination of alpha(1)-antitrypsin and alpha(1)-antichymotrypsin. Twenty-eight anesthetized rats received either Lex032 or NaCl 0.9% as a control solution during baseline conditions or after 1 h of complete reversible ischemia induced by microclip occlusion of the pancreatic arteries. The number of erythrocyte-perfused capillaries (functional capillary density) and the leukocyte adherence in postcapillary venules were assessed by intravital microscopy 45, 90, and 120 min after administration. In the baseline group, Lex032 increased leukocyte adherence compared with the NaCl 0.9% baseline group, without changing any other parameter. I/R without Lex-032 treatment resulted in a 50% reduction in functional capillary density, a 2-fold increase in leukocyte adherence, an increase in interleukin-6 serum concentration, and a significant fall in blood pressure during reperfusion time compared with baseline animals. Treatment with Lex032 in I/R resulted in significant preservation of capillary perfusion, an absence of interleukin-6 increase, and preservation of mean arterial pressure during reperfusion time, without changing the leukocyte adherence, compared with the NaCl 0.9% I/R group. Because of its considerable amelioration of microcirculatory perfusion, Lex032 might be useful in the treatment of pancreatic I/R tissue damage (e.g., cardiac bypass surgery, pancreas transplantation, and hemorrhagic shock) by prevention of capillary perfusion failure.
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PMID:Inhibition of neutrophil proteinases by recombinant serpin Lex032 reduces capillary no-reflow in ischemia/reperfusion-induced acute pancreatitis. 1041 92

Plasma concentrations of interleukin-1beta (IL-1beta), interleukin-6 (IL-6), C reactive protein (CRP) and alpha-1-antichymotrypsin (ACT) in 145 patients with probable Alzheimer's disease (AD) and 51 non-demented controls were measured. To investigate the cellular activation of peripheral immune system, plasma levels of neopterin were also investigated. Plasma levels of IL-1 were detectable in 17 patients with AD (13%) and only in one control (2%) and average levels of IL-1 were higher in AD patients than in controls (p < 0.001). IL-6 plasma levels were detectable in a higher proportion of AD and controls (53% and 27%, respectively), and were increased in patients with AD (p < 0.001). Plasma levels of ACT were increased in patients with AD (p < 0.001) and CRP levels were in the normal range. Plasma levels of neopterin were slightly lower in AD patients than in controls, but differences were not statistically significant. No significant correlation was observed between IL-1 and IL-6 levels or neopterin and cytokine levels in plasma from AD patients. Plasma levels of ACT negatively correlated with cognitive performances, as assessed by the mini mental state examination (MMSE; R = -0.26, p < 0.02) and positively correlated with the global deterioration state (GDS) of AD patients (R = 0.30, p < 0.007). Present findings suggested that detectable levels of circulating cytokines and increased ACT might not be derived by activation of peripheral immune system of AD patients. Detection of these molecules might be used for monitoring the progression of brain inflammation associated with AD.
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PMID:Increased plasma levels of interleukin-1, interleukin-6 and alpha-1-antichymotrypsin in patients with Alzheimer's disease: peripheral inflammation or signals from the brain? 1067 95

Proinflammatory cytokines and acute phase proteins, such as alpha(1)-antichymotrypsin, are over expressed in microglia and astrocytes in brain regions with abundant mature amyloid plaques, suggesting a glial cell-led brain acute phase response in the Alzheimer neuropathology. In this paper, we show that alpha(1)-antichymotrypsin gene expression in human astrocytes is elevated by interleukin-1 and interleukin-6, and further enhanced by glucocorticoid, while the homologous contrapsin gene in rat astrocytes is unaffected by these cytokines. These distinct gene regulation mechanisms might help to explain the differential susceptibility of humans and rodents to amyloid formation of the Alzheimer's type. In addition, we demonstrate that the alpha(1)-antichymotrypsin A-allele that encodes a different signal peptide and is a suggested risk factor for Alzheimer's disease gives rise to a reduced level of immature alpha(1)-antichymotrypsin in transfected cells. The physiological result would be an enhanced ability of the A-encoded alpha(1)-antichymotrypsin protein to become secreted and promote extracellular amyloid formation. We discuss our findings in terms of a model in which cytokine-induced alpha(1)-antichymotrypsin synthesis in astrocytes constitutes a specific inflammatory pathway that accelerates the development of Alzheimer's disease and could at least partly underlie the regional specificity and species restriction of the neuropathology.
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PMID:Effect of cytokines, dexamethasone and the A/T-signal peptide polymorphism on the expression of alpha(1)-antichymotrypsin in astrocytes: significance for Alzheimer's disease. 1157 71

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