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Early activation of hepatic NFkappaB and NF-IL6 in polymicrobial sepsis correlates with bacteremia, cytokine expression, and mortality.

BACKGROUND: The role of transcription factor activation in the pathophysiology of sepsis syndrome has not been established. This study investigated the relation between tissue nuclear factor kappaB (NFkappaB) and nuclear factor interleukin 6 (NF-IL6 or C/EBP) activation and bacteremia, inflammatory cytokine expression, and mortality in a murine model of cecal ligation and puncture (CLP). METHODS: Transcription factor activation was assessed by the electrophoretic mobility shift assay. Cytokine mRNA levels were established by reverse transcription-polymerase chain reaction and quantified by scanning densitometry. Bacteremia was evaluated by standard aerobic and anaerobic microbiologic methods. RESULTS: CLP stimulated hepatic NFkappaB activation at 2, 3, 4, 5, 6, and 8 hours compared with control and sham-operated mice. Hepatic NFkappaB activation during CLP peaked at 4 hours (1114% vs. no surgery, 609% vs. sham). Hepatic NF-IL6 activation was observed at 3, 4, and 6 hours after CLP. Hepatic and splenic levels of tumor necrosis factor-alpha and IL-6 mRNA were also elevated after CLP. Bacteremia in CLP mice consisted of Bacteroides species and to a lesser extent facultative gram-negative bacilli and group D Enterococcus. CONCLUSIONS: Early activation of hepatic and splenic NFkappaB and NF-IL6 positively correlates with tissue cytokine mRNA expression and mortality in a surgical model of polymicrobial sepsis. The data suggest that transcription factor activation is an early event in the pathophysiology of sepsis.

Animals↗

The Basic Amino Acid-Rich DNA-Binding Element of the NF-IL6 Transcription Factor Contains Two Functionally Distinct Subdomains.

Nuclear factor-interleukin-6 (NF-IL6), a human transcription factor of the CCAAT-box/enhancer binding protein (C/EBP) family, is widely implicated as a "master regulator" of hepatic acute-phrase response and inflammatory cytokine gene expression. NF-IL6 contains, at its N-terminus, an alanine- and proline-rich transactivation domain, followed at the C-terminus by a basic domain-leucine zipper (bZIP) DNA-binding motif. Understanding how the NF-IL6 transcription factor interacts with DNA is fundamental to its role as a transactivator because sequence-specific DNA-binding is prerequisite to promoter activation. We review our findings on the identification of the minimal "core" DNA-binding domain and the discovery of a novel bZIP element that influences DNA-binding kinetics. Manipulation of this domain allows for design of molecules that can be used as competitive antagonists or targeted delivery of molecules to selected regions of the eukaryotic genome.

Journal Article↗

The down-regulation of IL1alpha and IL6, in monocytes exposed to extracorporeal photopheresis (ECP)-treated lymphocytes, is not dependent on lymphocyte phosphatidylserine externalization.

Extracorporeal photopheresis (ECP) has been successfully used to treat some inflammatory conditions. Following ECP, lymphocytes become apoptotic and untreated monocytes, exposed to post-ECP lymphocytes, reduce proinflammatory cytokine secretion. This study attempted to establish if this monocyte immunosuppression was linked to phosphatidylserine externalization (detected using Annexin V) on the apoptotic lymphocytes. Using density gradient and magnetic separation, lymphocytes were isolated from three cutaneous T-cell lymphoma and nine chronic graft versus host disease (cGvHD) patients pre-ECP and prior to re-infusion (post-ECP). The collected lymphocytes were cultured overnight and Annexin V levels determined. Peripheral blood was taken from the same patient 20 h later and the monocytes were isolated. The 'fresh' monocytes were introduced to each 20 h pre- and post-ECP lymphocyte culture, stimulated with lipopolysaccharide (LPS) and Brefeldin A and subsequently tested for intracellular tumour necrosis factor alpha, interleukin 1 alpha (IL1alpha), IL1beta, IL6 and IL8. For cGvHD patients, the relative levels of IL1alpha and IL6 were reduced in the untreated, LPS-stimulated monocytes exposed to post-ECP lymphocytes. However, the down-regulation of IL1alpha and IL6 did not correlate to levels of Annexin V-positive lymphocytes. ECP-treated lymphocytes can reduce the ability of LPS-stimulated monocytes to produce some proinflammatory cytokines; however, this effect is not dependent on phosphatidylserine externalization.

Annexin A5↗

A case-control study in IL6 and TGFB1 gene polymorphisms and recurrent spontaneous abortion in southern Brazilian patients.

PROBLEM: A high proportion of recurrent spontaneous abortions (RSA) remains unexplained. Cytokine genotyping has been investigated. We studied the relationship between unexplained RSA, IL6 (-174 G-->C) and TGFB1 (+869, T-->C; +915, G-->C) gene polymorphisms. METHOD OF STUDY: The case-control study composed of 57 south Brazilian women, with unexplained RSA and 74 controls carefully matched was performed. Cytokine genotyping was performed by the polymerase chain reaction-sequence specific primer method, using the 'Cytokine Genotyping Tray'. RESULTS: The results showed that the genotypic frequencies did not differ from samples for TGFB1 gene. In relation to IL6 gene polymorphism there was a statistical difference in genotypic distribution between samples (P < or = 0.025). The frequency of the C/C genotype was increased in women with RSA in comparison with the frequency observed in controls: 18% versus 4% (P = 0.01). CONCLUSIONS: This result strengthened the importance of IL6 genotypes in the pathogenesis of RSA of unknown cause in the south Brazilian population.

Abortion, Habitual↗

A nuclear factor for interleukin-6 expression (NF-IL6) and the glucocorticoid receptor synergistically activate transcription of the rat alpha 1-acid glycoprotein gene via direct protein-protein interaction.

The acute-phase reaction is accompanied by an increase in a variety of serum proteins, named acute-phase proteins. The synthesis of these proteins is synergistically controlled by glucocorticoids and inflammatory cytokines such as interleukin-1 (IL-1), IL-6, and tumor necrosis factor alpha. Recently, we have cloned nuclear factor-IL-6 (NF-IL6), a transcription factor that activates the IL-6 gene, and have demonstrated its involvement in the expression of acute-phase-protein genes. We report here an analysis of the molecular mechanisms by which inflammatory cytokines and glucocorticoid act synergistically to activate expression of the rat alpha 1-acid glycoprotein (AGP) gene. We found that NF-IL6 and ligand-activated rat glucocorticoid receptor acted synergistically to transactivate the AGP gene and that maximal transcriptional activation of the AGP gene required expression of both intact NF-IL6 and rat glucocorticoid receptor. Surprisingly, however, transcriptional synergism was still observed even when one of the two factors lacked either its DNA-binding or transcriptional-activation function. We present evidence for a direct protein-protein interaction between these two distinct transcription factors and propose that this may be responsible for the synergistic activation of the rat AGP gene.

Acute-Phase Reaction↗

Determination of IL6, IL1, and IL4 in the plasma of patients with multiple myeloma.

Interleukin 6 (IL6) plasma levels were measured in 63 patients with multiple myeloma and 8 individuals with benign monoclonal gammopathy. 15 of these 71 samples showed by an enzyme linked immunosorbent assay (ELISA) detectable levels that ranged from 5 to 107 pg of IL6/ml. The IL6 levels of patients with multiple myeloma did not differ significantly from those of normal individuals (N = 25, range 5-27 pg IL6/ml) (Student's t-test, p = 0.295). The samples were negative for IL4; 3 were found positive for IL1 beta. A correlation between IL6, IL4 and IL1 beta levels and disease status was not observed for this group of patients.

Enzyme-Linked Immunosorbent Assay↗

Continuous veno-venous hemofiltration improves hemodynamics in septic shock with acute renal failure without modifying TNFalpha and IL6 plasma concentrations.

BACKGROUND: Continuous hemofiltration improves hemodynamics in critically ill patients by removing cytokines from the plasma. The mechanism, however, remains to be clarified since recent studies show conflicting findings. The present study was therefore designed to evaluate hemodynamic changes and kinetics of tumor necrosis factor (TNF)alpha, interleukin (IL)1beta and IL6 in patients with septic shock and acute renal failure (ARF) undergoing continuous veno-venous hemofiltration (CWHF), over a 24-hour period. METHODS: Eleven patients admitted to the ICU for septic shock with ARF were investigated with radial artery and pulmonary artery catheterization during isovolemic CWHF using AN69 hemofilters at a blood flow rate of 240 mL/min and ultrafiltration 1.65 +/- 0.33 L/h. Hemodynamic measurements (mean arterial pressure, right arterial pressure, pulmonary artery pressure, pulmonary vascular resistance, systemic vascular resistance, cardiac output and tissue oxygenation indeces) were obtained before and after 2h, 4h, 6h, 12h and 24 h of CVVHF. Blood samples from the pre- and postfilter lines and ultrafiltrate samples were collected for the radioimmunoassay of TNFalpha, IL1beta and IL6 before and at 2h, 4h, 6h, 12h and 24h. RESULTS: During CVVHF, mean arterial pressure rose from 67 +/- 7 mm Hg to 89 +/- 5 mm Hg (p < 0.05) and indexed systemic vascular resistance from 711 +/- 153 dyne.s.cm(-5)/m2 to 1,200 +/- 100 dyne.s.cm(-5)/m2 (p < 0.05). Serum lactate and oxygen consumption did not change. Mean arterial pressure and systemic vascular resistance were not correlated to the lowering of body temperature during CVVHF. Significant clearance of IL6 was achieved, but not of TNFa, though the plasma concentrations of both cytokines were unaffected throughout the study. IL1beta was not detectable. Two patients were discharged alive with normal renal function. CONCLUSION: In patients with septic shock and ARF, CVVHF improves mean arterial pressure and systemic vascular resistance. This effect does not appear to be related to the removal of cytokines. The effect of CVVHF on mortality and morbidity in the long term, in septic shock has still to be established.

Acute Kidney Injury↗

Analysis of IL6 and IL1A gene polymorphisms in UK and Dutch patients with sarcoidosis.

BACKGROUND: Proinflammatory cytokines are a major determinant in the inflammatory events leading to sarcoidosis. Genetic variations in the genes encoding these cytokines might contribute to sarcoidosis susceptibility, disease severity and outcome. METHODS: In the present study we genotyped two clinically well-defined cohorts of Caucasian sarcoidosis patients from different European countries (each with their own controls) for the following polymorphisms using SSP-PCR: IL6 -174(G/C), IL6 intron 4(A/G) and IL1A-889(C/T). In total, 516 individuals were studied (147 UK + 102 Dutch patients, 101 UK + 166 Dutch controls). Disease severity data at presentation included chest radiographic stage, FVC, DL(CO), and extrapulmonary manifestations. Disease progression was evaluated on follow-up chest radiographs and sequential lung function measurements (2, 4 years). RESULTS: No differences in genotype, carriage and allele frequencies of the investigated polymorphisms were found in either of the populations. Analysis of genotype data in relation to disease severity data, however, showed a slightly increased carrier frequency of the rarer-174C allele in patients with Stage IV sarcoidosis (p = 0.03, Pc = 0.09). Pulmonary function progression analysis did not reveal significant associations. CONCLUSIONS: Although the investigated polymorphisms are unlikely to contribute to sarcoidosis susceptibility, the IL6-174C allele might have a role in the genetics underlying sarcoidosis severity or the progression towards pulmonary fibrosis in a particular subgroup.

Adult↗

IL6 and lymphoproliferative disorders.

Interleukin 6 has pleiotropic effects on cells from various lineages. Several data indicate that it may play a critical role in the development of multiple myeloma by an autocrine or parcrine stimulation pathway. For instance, we showed that oligodeoxynucleotides antisens of IL6 mRNA were capable to decrease the proliferation of two different myeloma cell lines. In Waldenström's macroglobulinemia, at the initial stage of the disease, there is an autocrine differentiation pathway which is dependent of the secretion of IL6 by tumor cells. IL6 may also be implicated in the pathogenesis of some other lymphoid malignancies such as follicular lymphomas or large cell lymphomas. Its role in the systemic symptoms of Castleman disease has been clearly established.

Castleman Disease↗

[Production of IFN gamma, IL6 and IL10 by infiltrating cells of renal allografts and irreversible rejection: modulation by IL2 and IL4].

The frequency of isolated low density graft-infiltrating cells (GIC) secreting IFN gamma, IL6 and IL10 was studied in 8 cases of irreversible rejection of human renal allografts, using ELISPOT assays. The GIC were mostly CD8+ T cells although CD4+ T cells, B cells and macrophages could also be detected. In average, in 10(6) cells, 189 secreted IFN gamma, 747 IL10, and 17,114 IL6. Culture of GIC in the presence of IL2 resulted in an increase on the frequency of IFN gamma producing cells (IFN gamma-PC), in a dose dependent manner, with an optimal 6.5 fold increase at 50 U/ml. In contrast, 25 U/ml IL4 decreased the frequency of spontaneous and IL2 induced IFN gamma-PC. Furthermore, IL4 reduced the frequency of IL6-PC.

Graft Rejection↗

Acetaminophen-induced hepatotoxicity is associated with early changes in NF-kB and NF-IL6 DNA binding activity.

Nuclear transcription factors, such as NF-kB and NF-IL6, are believed to play an important role in regulating the expression of genes that encode for products involved in tissue damage and inflammation and, thus, may represent early biomarkers for chemical toxicities. In the present study changes in DNA binding activity of these factors were examined in livers of mice administered hepatotoxic doses of acetaminophen (APAP). NF-kB and NF-IL6 DNA binding occurred constitutively in control mouse liver. However, within 4 hr following administration of hepatotoxic doses of APAP, their binding activities were transiently lost and is in contrast to AP-1 transcription factor where activation occurs under similar conditions. These changes corresponded with increased release of inflammatory mediators (IL-6, serum amyloid A) and increased levels of enzymatic markers of hepatocyte damage. Similarly, treatment of mice with gadolinium chloride, an inhibitor of Kupffer cell activation and known to protect against APAP-induced hepatotoxicity, reduced the observed pathophysiological response in the liver while altering the APAP-associated changes in NF-kB DNA binding activity. NF-kB was found predominantly in parenchymal and endothelial cells and was composed primarily of relatively inactive p50 homodimer subunits in control liver. Taken together, these studies suggest that hepatotoxicity is associated with early and complex changes in DNA binding activities of specific transcription factors. In particular, NF-kB and NF-IL6 may serve as negative regulators of hepatocyte-derived inflammatory mediators and is analogous to that previously observed in certain other cell systems such as B lymphocytes.

Acetaminophen↗

NF-kappa B synergizes with NF-AT and NF-IL6 in activation of the IL-4 gene in T cells.

IL-4 plays a pivotal role in the development of the Th2 cell mediated humoral immune response and causes IgE-dependent allergic inflammatory diseases. Expression of IL-4 in differentiated Th2 cells is regulated by transcription factors such as NF-AT, AP-1 and NF-IL6. Recently, increasing evidence indicates that the pro-inflammatory transcription factor NF-kappa B may also participate inIL-4 expression. In this study, we show that the IL-4 promoter is synergistically activated by NF-kappa B, NF-AT and NF-IL6 at the NF-kappa B/NF-AT/NF-IL6 composite sites. In addition, we performed the chromatin immunoprecipitation technique to determine the functional relevance of NF-kappa B in the activation of the IL-4 gene in vivo. We demonstrate that NF-kappa B binds to the IL-4 promoter in vivo upon T cell activation. Inhibition of NF-kappa B nuclear translocation in living cells blocked binding of NF-kappa B to the IL-4 promoter. The data provide first evidence that NF-kappa B is directly involved in IL-4 transcription.

Gene Expression Regulation↗

The relationship between altered membrane composition, eicosanoids and TNF-induced IL1 and IL6 production in macrophages of rats fed fats of different unsaturated fatty acid composition.

The study investigated the changes in individual molecular species in PE and the effects of a variety of dietary fats with varying proportions of saturated and unsaturated fatty acids on membrane composition, eicosanoid production and cytokine production in thioglycollate-elicited rat macrophages. The data obtained indicates that the greatest degree of modulation by dietary fats on cytokine production was observed after 8 weeks feeding and at this time, the total diacyl species containing linoleic acid (18:2 n-6) and arachidonic acid (20:4 n-6) at the sn-2 position related in a curvilinear fashion to total 18:2 n-6 intake and that IL1 and IL6 production related in a curvilinear fashion to the total diacyl species with 20:4 and 18:2 at the sn-2 position. After 4 weeks of feeding, fish and olive oils enhanced production of IL6 and LTB4, however, while IL1 production, after 8 weeks of dietary treatment, was greatest from macrophages of animals fed corn and olive oils, PGE2 production was greatest in the former group and LTB4 production in the latter. Thus an eicosanoid effect may explain the modulatory influence of olive oil and IL1 production but, cannot explain the effect of corn oil on production of the cytokine. The data from the present study provides some insight into how dietary fats could provide therapy for conditions in which inflammatory cytokines are implicated.

Animals↗

Polymorphisms of interleukin-1 gene complex, IL6 and tumour necrosis factor genes in chronic idiopathic neutropenia of adults.

Chronic idiopathic neutropenia of adults (CINA) is a granulocytic disorder characterised by the "unexplained" decrease in the number of circulating neutrophils. Serum inflammatory cytokines and chemokines are increased in CINA. In addition, cytokines gene polymorphisms are associated with increased levels of respective products and related with inflammatory diseases. The aim of the present study was to investigate the association of polymorphisms of IL1B-511C/T and +3953C/T, IL1RN intron 2, IL6-174G/C and TNF-308G/A genes with CINA. We analysed 29 CINA and controls by polymerase chain reaction and restriction fragment length polymorphism. Statistical analyses were performed using chi2 test, and the Hardy-Weinberg equilibrium (HWE) was investigated. All alleles analysed were in HWE in both populations. Similar frequencies of IL1B-511C/T, IL1B+3953C/T, IL1RN, IL6-174G/C and TNF-308G/A genotypes were observed in CINA and controls. These results suggest that cytokine polymorphisms associated with control of gene expression and protein levels were not associated with occurrence of CINA and were not responsible for the increased cytokine in CINA patients.

Adult↗

Linkage and association of the CA repeat polymorphism of the IL6 gene, obesity-related phenotypes, and bone mineral density (BMD) in two independent Caucasian populations.

Genetic factors play an important role in osteoporosis and obesity, two serious public health problems in the world. We investigated the relationships between obesity-related phenotypes, bone mineral density (BMD) and the CA repeat polymorphism of the IL6 gene in two large independent samples using the quantitative transmission disequilibrium test (QTDT). The first sample consisted of 1,816 individuals from 79 multigenerational pedigrees. Each pedigree was identified through a proband with BMD Z-scores </=-1.28 at the hip or spine. The second sample was a randomly ascertained set of 636 individuals from 157 nuclear families. Ten alleles containing 9-18 CA repeats were identified in our Caucasian populations. For body mass index (BMI), fat mass and percentage fat mass (PFM), highly significant (P<0.01) or significant (P<0.05) results were found for linkage in our sample of nuclear families and for association in the multigenerational pedigrees. We also observed weak evidence for linkage (P=0.069) with spine BMD and for association with hip BMD in the sample of multigenerational pedigrees. Our results suggest that genetic variation in or near the IL6 locus may be involved in the etiology of obesity and osteoporosis.

Adult↗

Hypothermia as an indicator of the acute effects of lipopolysaccharides: comparison with serum levels of IL1 beta, IL6 and TNF alpha.

1. Hypothermia was investigated as a parameter indicating the severity of the acute effects of lipopolysaccharides (LPS) in BALB/c mice, and was compared with the induction of serum levels of IL1 beta, TNF alpha and IL6. 2. Hypothermia induced by low doses of LPS (10-50 micrograms/mouse IP LPS E. coli 0111:B4) peaked at 2 hr after LPS and then either plateaued (50 micrograms) or declined. LPS, 100 and 300 mu, induced greater degrees of hypothermia that plateaued or continued to increase with time for 8 hr. Higher doses of LPS induced similar levels of hypothermia until 4 hr but then continued to increase markedly until 8 hr. 3. TNF alpha levels peaked early (1-2 hr) and declined rapidly, IL6 levels peaked at 3 hr and then declined slowly, and IL1 beta levels peaked at 4 hr, declined at lower doses of LPS, plateaued at higher doses and continued to slowly increase at highest doses. 4. The peak levels of the cytokines (IL1 beta up to 4 hr) and hypothermia (4 hr) increased in relation to the dose of LPS and maximum responses were apparently achieved in all cases at 300-1000 micrograms LPS. 5. A similar parallel between hypothermia and induction of cytokines was observed in C57BL6 and OF1 mice, which were good and poor responders to LPS, respectively, and with the more potent Shigella dysenteria LPS in BALB/c mice. 6. In conclusion, hypothermia is a useful parameter for indicating the strength of the acute effects of LPS. Further studies are necessary to determine whether or not the cytokines studied here play a causative role in hypothermia.

Animals↗

Iloprost treatment reduces TNF-alpha production and TNF-RII expression in critical limb ischemia patients without affecting IL6.

Iloprost, a stable prostacyclin analogue, regulates expression of genes that are involved in inflammation and in cell growth and inhibits the in vitro production of cytokines. We evaluated the effect of an in vivo weekly iloprost treatment on TNF-alpha and IL6 monocyte production (evaluated by ELISA), on monocyte apoptosis (Annexin V/uptake of propidium iodide by flow cytometry) and on peripheral blood mononuclear cell (PBMC) TNF-alpha receptors (TNF-RI and TNF-RII) mRNA expression (RT-PCR) in 14 atherosclerotic critical limb ischemia patients. PBMC were stimulated with LPS for 24h. TNF-alpha production was significantly reduced by iloprost whereas IL6 production was not affected. Iloprost did not accelerate monocyte apoptosis. TNF-RI mRNA expression was not modified by iloprost, whereas TNF-RII mRNA expression was significantly reduced. Our data show that iloprost may have anti-inflammatory effects in addition to the well-known vasodilatatory and anti-aggregant ones.

Aged↗

Failure of FIV-infected cats to control Toxoplasma gondii correlates with reduced IL2, IL6, and IL12 and elevated IL10 expression by lymph node T cells.

Increased susceptibility to intracellular pathogens in HIV-infected individuals and FIV-infected cats is attributed to a defective T-helper 1 (Th1) immune response. However, little is known about specific cytokine responses to secondary pathogens. To address this question, control and FIV-infected cats were challenged with Toxoplasma gondii, and lymph node cells analyzed for cytokine mRNA expression. Twenty-four weeks post-FIV infection, prior to T. gondii challenge, IL2 and IL12 mRNAs were depressed, whereas IL10 and IFNgamma mRNAs were increased in CD4+ and CD8+ subsets. Following T. gondii challenge, control cats showed increased expression of IL2, IFNgamma, IL10, IL12, and IL6 mRNAs. In contrast, IL2, IL6, IFNgamma, and IL12 mRNAs were suppressed in FIV-T. gondii co-infected cats, whereas IL10 remained at the high prechallenge levels. IFNgamma and IL10 mRNAs were produced by both CD4+ and CD8+ cells in FIV-T. gondii cats. Elevated IL10 may suppress a Th1 cytokine response to T. gondii challenge.

Animals↗