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

Human squamous carcinoma (COLO-16) cells synthesize and secrete hepatocyte-stimulating factor-III (HSF-III), a glycoprotein with Mr = 39,000, which stimulates the synthesis of several acute phase plasma proteins in human hepatoma (HepG2) cells. The qualitative response of HepG2 cells to HSF-III is essentially the same as that elicited by human recombinant interleukin-6 (IL-6). Although similar in hepatocyte-stimulating activity, HSF-III and IL-6 are distinct molecules which differ not only in size and charge but also in immunologic properties: no cross-recognition of HSF-III and IL-6 occurs using neutralizing antibodies against IL-6 and HSF-III, respectively. In addition, Northern blot hybridization of IL-6 cDNA to mRNA from COLO-16 cells revealed no detectable IL-6 message. HSF-III does not compete for binding to the IL-6 receptors suggesting that HepG2 cells carry receptors specific for each hormone. Both receptor types may trigger similar intracellular processes explaining the identical regulation of acute phase protein expression.
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PMID:Human hepatocyte-stimulating factor-III and interleukin-6 are structurally and immunologically distinct but regulate the production of the same acute phase plasma proteins. 247 Jul 40

One of the mediators responsible for the induction of the production of acute phase proteins by hepatocytes is interleukin-6 (IL-6), formally known as hybridoma growth factor (HGF). In a prospective study the biological significance of IL-6, but also the relationship with the acute phase response (C-reactive protein [CRP], alpha 1-antitrypsin and alpha 1-acid glycoprotein) during flare-ups in 12 systemic lupus erythematosus (SLE) patients was investigated. Only 2 SLE patients showed sustained elevated IL-6 levels, and in one of these patients a clear correlation was found between the increases in IL-6 and the acute phase response. In the other SLE patients hardly any response or change in the levels of IL-6, CRP, and/or alpha 1-antitrypsin was found. In contrast to the profiles of alpha 1-acid glycoprotein, in seven of the SLE patients a significant increase in the serum levels took place in the period preceding the exacerbation. This difference between the three acute phase proteins suggests that the regulatory mechanisms are different. Our results are in agreement with the findings that IL-6 might be responsible for the CRP response.
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PMID:Interleukin-6 (IL-6) and acute phase proteins in the disease course of patients with systemic lupus erythematosus. 247 Dec 49

In the rodent, the general response to acute inflammation and tissue damage is characterized by a complex rearrangement in the pattern of concentrations of proteins in the plasma leading to an increase in the sedimentation rate of erythrocytes, an increase in leukocyte concentration in the bloodstream, and a decrease in the hematocrit. Body temperature changes only slightly or not at all. The reasons for the change in plasma concentrations of proteins are changes in their rates of synthesis in the liver. Degradation of plasma proteins is not affected. The details of the acute phase response evolved in the interaction of species with their environment. Therefore, it is not surprising to find differences in the details of the acute phase response among species. For example, alpha 2-macroglobulin is a strongly positive acute phase reactant in the rat, but not in the mouse; C-reactive protein is a strongly positive acute phase protein in the mouse, but is not found in the rat. An inducible acute phase cysteine proteinase inhibitor system, which has evolved from a primordial kininogen gene, has been observed so far only in the rat. The changes in the synthesis rates of acute phase proteins during inflammation are closely reflected by corresponding changes in intracellular mRNA levels. In the liver, the capacity to induce the acute phase pattern of synthesis and secretion of plasma proteins probably develops around birth. Changes in mRNA levels are brought about by changes in transcription rates or by changes in mRNA stability. Kinetics of mRNA changes during the acute phase response differ for individual proteins. The main signal compound for eliciting the acute phase response in liver seems to be interleukin-6/interferon-beta 2/hepatocyte stimulating factor, whereas interleukin-1 leads to typical acute phase changes in mRNA levels only for alpha 1-acid glycoprotein, albumin, and transthyretin. Plasma protein genes are expressed in various extrahepatic tissues, such as the choroid plexus, the yolk sac, the placenta, the seminal vesicles, and other sites. All these tissues are involved in maintaining protein homeostasis in associated extracellular compartments by synthesis and secretion of proteins. Synthesis and secretion of plasma proteins in paracompartmental organs other than the liver is not influenced by the acute phase stimuli.
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PMID:The acute phase response in the rodent. 247 96

The synthesis of all the major acute phase plasma proteins is stimulated in rat hepatoma and primary cultures of hepatocytes by three, structurally and functionally distinct groups of hormones: 1) hepatocyte-stimulating factors (HSF) and interleukin-6 (IL-6); 2) interleukin-1 (IL-1) and tumor necrosis factor (TNF); and 3) glucocorticoids. Each plasma protein gene requires a specific combination of these 3 hormone types for maximal expression. One set of acute phase proteins, including alpha 2-macroglobulin, alpha 1-antichymotrypsin ( = contrapsin), cysteine protease inhibitor ( = thiostatin), alpha 1-antitrypsin, ceruloplasmin and fibrinogens are predominantly regulated by the keratinocyte-derived HSF-III/-II or IL-6, while a second set of proteins, including alpha 1-acid glycoprotein (AGP), haptoglobin and complement C3 are predominantly regulated by keratinocyte-derived HSF-I, IL-1 or TNF. In conjunction with the above peptide hormones, glucocorticoids synergistically enhance the stimulated expression of most, but not all, acute phase proteins. An exceptionally strong synergy between HSF (or IL-6), IL-1 and glucocorticoids is noted for the activation of the AGP gene. To elucidate the molecular mechanisms of regulation, we have identified the cis-acting genetic elements through which all these hormones control the transcriptional activity of the AGP gene. It appears that acute phase activates a specific nuclear binding protein in the rat liver that interacts with the peptide hormone responsive element located 5 kb upstream of the transcriptional start site.
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PMID:Regulation of acute phase protein genes by hepatocyte-stimulating factors, monokines and glucocorticoids. 248 67

The regulation of the synthesis of alpha-2-HS glycoprotein (AHSG) by inflammatory mediators from activated monocytes was studied on the human hepatoma cell line HepG2 and compared to that of albumin. Monocyte-conditioned medium, recombinant human interleukin-6 (rhIL6) and interleukin-1 beta (rhIL1 beta) all down-regulated the synthesis of AHSG. This decrease was found both at the protein and the mRNA level. The most efficient mediator was the monocyte-conditioned medium, when rhIL1 beta was found to be less efficient than rhIL6. The combination of rhIL6 and rhIL1 beta resulted in an additive down-regulation of the AHSG mRNA levels. Similar results were obtained with albumin. These data indicate that AHSG is a negative acute-phase protein whose synthesis is regulated by cytokines in a manner similar to that of albumin.
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PMID:The synthesis of human alpha-2-HS glycoprotein is down-regulated by cytokines in hepatoma HepG2 cells. 284 21

The cDNA for human beta 2-interferon (IFN-beta 2)/B-cell differentiation factor 2/hepatocyte-stimulating factor was expressed in Escherichia coli to yield a fusion protein which contains the 182 carboxyl-terminal amino acids of IFN-beta 2 fused to a 34-amino acid prokaryotic leader peptide (rIFN-beta 2). When added to cultures of human hepatoma cell line Hep3B2, rIFN-beta 2 as well as preparations of natural IFN-beta 2 enhance secretion of positive acute phase reactants such as alpha 1-antichymotrypsin, complement C3, fibrinogen, and alpha 1-acid glycoprotein and inhibit secretion of albumin, confirming that a protein derived from the IFN-beta 2 gene can have hepatocyte-stimulating factor activity. We have prepared a rabbit polyclonal antiserum to the E. coli-derived human IFN-beta 2 fusion protein. This polyclonal antiserum inhibits the hepatocyte-stimulating and B-cell differentiation activities of appropriate IFN-beta 2 preparations. The anti-rIFN-beta 2 antiserum has been used in immunoprecipitation experiments and in Western blots to help define the secretory proteins derived from the IFN-beta 2 gene in fibroblasts and monocytes. "Uninduced" human FS-4 fibroblasts as well as those induced with interleukin-1 alpha, tumor necrosis factor, or bacterial lipopolysaccharide secrete at least five forms of IFN-beta 2 of apparent molecular mass in the range from 23 to 30 kDa which can be resolved by polyacrylamide gel electrophoresis under denaturing and reducing conditions. The three higher molecular mass forms are not observed when FS-4 cells are induced in the presence of tunicamycin, suggesting that these forms are N-glycosylated (gp28, gp29, and gp30). Although secretion of the two lower molecular mass forms is resistant to tunicamycin, they are labeled by [3H]glucosamine (gp23-gp25). The inclusion of cycloheximide during the [35S]methionine labeling of induced FS-4 cells results in the preferential synthesis and secretion of the 29-kDa triplet. Human monocytes induced with bacterial lipopolysaccharide also secrete several distinct forms of IFN-beta 2 in the size range from 23 to 30 kDa which co-migrate in polyacrylamide gels with those obtained from FS-4 cells. Our observations help relate previous descriptions of multiple forms of hepatocyte-stimulating factor to specific proteins derived from the IFN-beta 2 gene.
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PMID:Synthesis and secretion of multiple forms of beta 2-interferon/B-cell differentiation factor 2/hepatocyte-stimulating factor by human fibroblasts and monocytes. 313 26

Interleukin-6 (IL-6), also called 26-kd protein, hybridoma plasmacytoma growth factor, beta 2-interferon, or B cell stimulatory factor 2, is a recently described human cytokine with multiple growth and differentiation activities. Using a very sensitive bioassay based on the growth factor activity of this protein for B cell hybridomas, we found that IL-6 activity was significantly elevated in synovial fluid from patients with rheumatoid arthritis (RA) or other inflammatory arthritides, as compared with that in a group of patients with osteoarthritis. Moreover, IL-6 was detected in about one-third of the serum samples from patients with RA. In the latter group, we found a significant correlation between serum IL-6 activity and serum levels of C-reactive protein, alpha 1-acid glycoprotein, alpha 1-antitrypsin, fibrinogen, and haptoglobin, which indicates that IL-6 is related to disease activity in patients with RA.
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PMID:Interleukin-6 in synovial fluid and serum of patients with rheumatoid arthritis and other inflammatory arthritides. 326 Jan 2

Angiotensinogen has been assumed to be an acute-phase protein, because some forms of acute inflammation, eg, the injection of lipopolysaccharide or cellite or partial hepatectomy, increased the hepatic synthesis of angiotensinogen. In addition, the well-characterized nephrectomy-induced stimulation of angiotensinogen was thought to represent an acute-phase reaction. To evaluate this hypothesis, we examined changes in angiotensinogen secretion by the isolated perfused rat liver after the systemic administration of turpentine or lipopolysaccharide as well as in response to nephrectomy or sham nephrectomy. Comparison was made with the secretion of two typical acute-phase proteins, alpha 1-acid glycoprotein and alpha 2-macroglobulin, and with the secretion of the negative acute-phase protein albumin. All forms of experimental surgery stimulated the secretion of both control acute-phase proteins several-fold. In contrast, the response of angiotensinogen was not uniform; lipopolysaccharide and bilateral nephrectomy stimulated secretion twofold to threefold, sham nephrectomy had no effect, and turpentine decreased the secretion to 30% of the control level. A similar inhomogeneity was found in an additional experiment performed to analyze the direct effects of interleukin-1 or interleukin-6 on the secretion of angiotensinogen by freshly isolated hepatocytes. Interleukin-6 increased but interleukin-1 decreased the mRNA and secretion of angiotensinogen, whereas both cytokines increased the secretion of both acute-phase proteins. Because of this nonuniform behavior of angiotensinogen, it is premature to classify angiotensinogen as an acute-phase protein until a specific function for angiotensinogen during acute inflammation is known.
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PMID:Angiotensinogen: an acute-phase protein? 750 96

Tumor necrosis factor alpha (TNF alpha) and interleukin-6 (IL-6) play a main role in inducing acute phase protein production by hepatocytes. This study describes the serum levels of TNF alpha and IL-6 in relation to serum levels of C-reactive protein (CRP) and alpha 1-acid glycoprotein (alpha 1AG) in three systemic lupus erythematosus (SLE) patients. Disease courses of these patients were divided in a total of 19 clinical periods, according to the clinical symptoms and interleukin profiles. Significantly elevated TNF alpha levels were found in all but three of the defined periods, without being associated with disease activity. In only four of the defined periods elevated TNF alpha were observed combined with elevated IL-6 and CRP levels. Two of these periods coincided with minor symptoms of SLE, one with an exacerbation and the other one with a systemic infection while SLE activity was low. All other periods showed varying combinations of elevated TNF alpha and/or IL-6 levels being followed or not by elevated CRP levels. Significantly raised alpha 1AG levels were measured in all clinical periods. In most of the observed periods a dissociation was found between TNF alpha and IL-6 and also between the different cytokine (TNF alpha and IL-6) levels and acute phase protein (CRP and alpha 1AG) levels. These data could not be explained by differences in disease course or influences of medication. We conclude that more factors other than TNF alpha and IL-6 must play a role in the regulatory pathway of the acute phase response in SLE.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Profiles of cytokines (TNF alpha and IL-6) and acute phase proteins (CRP and alpha 1AG) related to the disease course in patients with systemic lupus erythematosus. 751 Oct 20

To clarify the mechanism involved in regulating the secretion of albumin and alpha 1-acid glycoprotein by rat hepatocytes, we studied hepatocyte culture and cocultures of hepatocyte and liver nonparenchymal cells. The secretion of alpha 1-acid glycoprotein by hepatocytes was stimulated and that of albumin was inhibited by combinations of dexamethasone and monokines, especially by dexamethasone and interleukin-6. The secretion of these proteins was equally inhibited during stimulation by lipopolysaccharide in cocultures. The inhibitory effect of sinusoidal endothelial cells was smaller than that of Kupffer cells. This inhibition was partially abolished by blocking the nitric oxide synthase pathway in cocultured cells and was completely abolished by dexamethasone. In conclusion, the secretion of albumin and alpha 1-acid glycoprotein by hepatocytes was regulated by monokines, dexamethasone, and the inducible nitric oxide synthase pathway in hepatocytes and liver nonparenchymal cells in vitro.
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PMID:Regulation of hepatocyte albumin and alpha 1-acid glycoprotein secretion by monokines, dexamethasone, and nitric oxide synthase pathway: significance of activated liver nonparenchymal cells. 751 18


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