Hypertonic saline solution (NaCl 7.2%) enhances renal excretion of acids in cattle with acute ruminal lactic acidosis

The present study aimed to evaluate the efficiency of hypertonic saline solution (HSS) as a novel treatment of acute ruminal lactic acidosis (ARLA) in cattle, focusing on urinary excretion of acids. Twelve cannulated steers were submitted to experimentally induced ARLA by adminis- tering sucrose into the rumen. Twenty hours later, the cattle were randomly divided into two equal groups. The first group was treated with 7.5% HSS (5 mL/kg) over 15 min, and isotonic saline solution (ISS; 20 mL/kg) for the subsequent 165 minutes. The control group was administered ISS instead of HSS. Rumen and urine samples were collected at different times during the experiment from the baseline to 64 h post-induction. The induction caused a medium-to-moderate ruminal acidosis, and a moderate degree of systemic acidosis and dehydration. Steers treated with HSS increased by 50% its glomerular filtration rate (1.61 mL/min) compared to ISS group (1.06 mL/ min; p⟨0.03). The overall volume of urine excreted by HSS group was higher than that in ISS group (1.62 L vs 0.7 L; p⟨0.02). This increase in total volume of urine provided by HSS favored a greater excretion of H+ ions in urine, which was 3.39-fold higher in HSS group (64.3*10-7 vs 18.9*10-7 Mol) as well as lactate (241.7 vs 181.8 mMol) and P urinary excretion (3.8 vs 1.1 mMol) that reduced the urine pH (5.3 vs 5.7). Only the HSS group decreased significantly blood total lactic acid concentration (20.3 %) throughout the treatment. A positive relationship was found between the excretion of urinary phosphorus and urinary pH (r2=0.562). The results showed that this novel treatment with HSS enhanced renal excretion of acids and may be recommended as an additional treatment for cattle with lactic acidosis.

Avaliação hemogasométrica, bioquímica e hematológica de ovinos suplementados com melão

RESUMOO presente trabalho avaliou os efeitos da administração de duas diferentes quantidades de melão sobre variáveis hemogasométricas, bioquímicas e hematológicas de ovinos não adaptados. Foram utilizados 12 ovinos canulados, pesando 25kg de peso vivo, que nunca receberam ração concentrada. Os animais receberam dieta à base de feno (2,3% do peso vivo) e água à vontade. Os ovinos foram distribuídos aleatoriamente em dois grupos e receberam 25% ou 75% da matéria seca (MS) da dieta de melão triturado (G25% e G75%, respectivamente) diretamente no rúmen. Foram realizadas coletas de sangue e determinação do pH ruminal nos seguintes tempos: zero, 3, 6, 12, 18 e 24 horas após oferecimento do melão. Foi realizada análise hemogasométrica, do volume globular, determinação da concentração plasmática de lactato-L, glicose e osmolaridade sérica. No G25%, o pH sanguíneo variou entre 7,40 e 7,31, enquanto o G75% apresentou pH entre 7,38 e 7,26. Maiores concentrações de glicose plasmática foram detectadas no G75% no T3, T6 e T12 (P<0,05). Os ovinos que receberam 25% de melão mantiveram parâmetros sanguíneos dentro da normalidade, ao passo que, no G75%, os ovinos apresentaram discreta acidose metabólica sistêmica e hiperglicemia. A suplementação com 25% de melão pode ser uma alternativa segura na alimentação de ovinos.

Double-stranded RNA-activated protein kinase is a key modulator of insulin sensitivity in physiological conditions and in obesity in mice

The molecular integration of nutrient- and pathogen-sensing pathways has become of great interest in understanding the mechanisms of insulin resistance in obesity. The double-stranded RNA-dependent protein kinase (PKR) is one candidate molecule that may provide cross talk between inflammatory and metabolic signaling. The present study was performed to determine, first, the role of PKR in modulating insulin action and glucose metabolism in physiological situations, and second, the role of PKR in insulin resistance in obese mice. We used Pkr(-/-) and Pkr(+/+) mice to investigate the role of PKR in modulating insulin sensitivity, glucose metabolism, and insulin signaling in liver, muscle, and adipose tissue in response to a high-fat diet. Our data show that in lean Pkr(-/-) mice, there is an improvement in insulin sensitivity, and in glucose tolerance, and a reduction in fasting blood glucose, probably related to a decrease in protein phosphatase 2A activity and a parallel increase in insulin-induced thymoma viral oncogene-1 (Akt) phosphorylation. PKR is activated in tissues of obese mice and can induce insulin resistance by directly binding to and inducing insulin receptor substrate (IRS)-1 serine307 phosphorylation or indirectly through modulation of c-Jun N-terminal kinase and inhibitor of κB kinase β. Pkr(-/-) mice were protected from high-fat diet-induced insulin resistance and glucose intolerance and showed improved insulin signaling associated with a reduction in c-Jun N-terminal kinase and inhibitor of κB kinase β phosphorylation in insulin-sensitive tissues. PKR may have a role in insulin sensitivity under normal physiological conditions, probably by modulating protein phosphatase 2A activity and serine-threonine kinase phosphorylation, and certainly, this kinase may represent a central mechanism for the integration of pathogen response and innate immunity with insulin action and metabolic pathways that are critical in obesity.

Prevalence, treatment, and outcomes of the hepatic artery stenosis after liver transplantation

INTRODUCTION

Hepatic artery stenosis (HAS) after liver transplantation can lead to altered hepatic function and/or thrombosis, there by increasing morbidity and mortality. The prevalence of HAS in the literatures varies from 4% to 11%.

OBJECTIVE

We sought to describe the prevalence and treatment of hepatic artery stenosis.

METHODS

We performed a descriptive retrospective analysis of 253 liver transplantations from March 1998 to May 2007, including patients with suspected HAS owing to increased hepatic enzymes, altered Doppler ultrasound (us) and hepatic biopsy. The confirmation of HAS was achieved through areriography.

RESULTS

Nine patients were identified to have HAS, a 3.5% prevalence. Among the HAS patients, seven were male and two female. Their average age was 35.5 years (range, 65 to 53). The average time between the diagnosis and transplantation was 14.2 months (range, 9 to 68). The increase in hepatic enzymes among this group averaged: aspartate aminotransferase 131 U/L (range, 26 to 412) and alanine aminotransferase 192 U/L (range, 35 to 511). Doppler US showed alteration in the resistance level index. All patients underwent areriography; only one could not be treated owing to severe hepatic artery spasm, which also occurred during another attempt weeks after the first one. Among the eight patients, six were treated with stents and two with angioplastis. All treated patients displayed improvements in parameters. Four patients treated with stents required retreatment: two underwent angioplasty and two, a thrombolytic. One graft rethrombosed but evolved in compensated fashion with recanalization by collaterals. There has been no graft loss or mortality in this population. The average time of posttreatment follow-up was 31.28 (range, 9 to 68) months.

CONCLUSION

The prevalence of HAS in our unit was within that reported in the literature. Treatment with a stent or angioplasty proved to be efficient to control this complication, considering that hepatic function recovered and that there was neither graft nor patient loss.

Prevalence, treatment, and outcomes of the hepatic artery stenosis after liver transplantation

INTRODUCTION

Hepatic artery stenosis (HAS) after liver transplantation can lead to altered hepatic function and/or thrombosis, there by increasing morbidity and mortality. The prevalence of HAS in the literatures varies from 4% to 11%.

OBJECTIVE

We sought to describe the prevalence and treatment of hepatic artery stenosis.

METHODS

We performed a descriptive retrospective analysis of 253 liver transplantations from March 1998 to May 2007, including patients with suspected HAS owing to increased hepatic enzymes, altered Doppler ultrasound (us) and hepatic biopsy. The confirmation of HAS was achieved through areriography.

RESULTS

Nine patients were identified to have HAS, a 3.5% prevalence. Among the HAS patients, seven were male and two female. Their average age was 35.5 years (range, 65 to 53). The average time between the diagnosis and transplantation was 14.2 months (range, 9 to 68). The increase in hepatic enzymes among this group averaged: aspartate aminotransferase 131 U/L (range, 26 to 412) and alanine aminotransferase 192 U/L (range, 35 to 511). Doppler US showed alteration in the resistance level index. All patients underwent areriography; only one could not be treated owing to severe hepatic artery spasm, which also occurred during another attempt weeks after the first one. Among the eight patients, six were treated with stents and two with angioplastis. All treated patients displayed improvements in parameters. Four patients treated with stents required retreatment: two underwent angioplasty and two, a thrombolytic. One graft rethrombosed but evolved in compensated fashion with recanalization by collaterals. There has been no graft loss or mortality in this population. The average time of posttreatment follow-up was 31.28 (range, 9 to 68) months.

CONCLUSION

The prevalence of HAS in our unit was within that reported in the literature. Treatment with a stent or angioplasty proved to be efficient to control this complication, considering that hepatic function recovered and that there was neither graft nor patient loss.

Complications following transjugular intrahepatic portosystemic shunt: a retrospective analysis

Transjugular intrahepatic portosystemic shunt (TIPS) has been the therapeutic option for severe decompensation of chronic liver disease and as a bridge to liver transplantation. The aim of this study was to analyze the complications of this procedure. The records of 47 patients (39 men) of mean age 48 years underwent TIPS procedures from 1998 to 2003 were reviewed. Forty-one patients received 45 successful TIPS; it failed in six patients. Improvement was observed in 20 of 28 patients with upper gastrointestinal bleeding (71%); 9 of 11 with ascites (82%); and 5 of 8 with impaired renal function (62%). The Child-Pugh scores improved in 6 of the 47 patients (13%). Transplantation was performed in 11 patients (23%). The complications were: encephalopathy (49%); infection (19%); renal failure (17%); TIPS migration to the portal vein (4%) and to the right atrium (4%). Mortality was 32% (15/47) over 3 months. Eight patients developed active bleeding during TIPS installation requiring mechanical ventilation and intensive care, and died within the first week. Other causes of death were sepsis (n = 2), liver failure (n = 1), accidental puncture of the Glisson's capsule leading to intra-abdominal bleeding (n = 1) and refractory upper gastrointestinal bleeding (n = 3). The latter four patients had TIPS placement failure. In conclusion, TIPS produced clinical improvement among 51% of patients with complications in 49%. The main complications were encephalopathy (49%), infection (19%), and renal failure (17%). The 3-month mortality rate after TIPS placement was 32%.

Quantitative and qualitative interferences of pentoxifillyne on hepatic Schistosoma mansoni granulomas: effects on extracellular matrix and eosinophil population

Mast cells and eosinophils actively participate in tissue repair and are prominent components of Schistosoma mansoni granulomas. Since pentoxifillyne (PTX) is an immunomodulatory and antifibrotic substance, we aimed to characterize, by morphological techniques, the effect of this drug on fibrosis developed inside murine hepatic schistosomal granulomatous reaction, beyond the quantification of eosinophil and mast cell populations. The drug (1 mg/100 g animal weight) was administrated from 35 to 90 days post-infection, when the animals were killed. The intragranulomatous interstitial collagen network was analyzed by confocal laser scanning microscopy, the number of eosinophils and mast cells was quantified and the results were validated by t-student test. Treatment did not interfere on the granuloma evolution but caused a significant decrease in the total and involutive number of hepatic granulomas (p = 0.01 and 0.001, respectively), and in the intragranulomatous accumulation of eosinophils (p = 0.0001). Otherwise, the number of mast cells was not significantly altered (p = 0.9); however, it was positively correlated with the number of granulomatous structures (r = 0.955). In conclusion, PTX does not affect development and collagen deposition in S. mansoni murine granuloma, but decreases the intragranulomatous eosinophil accumulation possibly due to its immunomodulatory capability, interfering in cellular recruitment and/or differentiation.

Significant overexpression of oligophrenin-1 in colorectal tumors detected by cDNA microarray analysis

The human oligophrenin-1 gene is ubiquitously expressed at low levels and expressed at high levels in the developing neuroepithelium of the neural tube. Mutations in this gene have been related to the X-linked mental retardation. Using cDNA microarrays, we found evidence that oligophrenin-1 is strongly up-regulated in colorectal tumors. Semiquantitative reverse transcriptase polymerase chain reaction confirmed this finding. Thus, a well-known nervous system-associated human gene transcript may also be an important colorectal tumor marker and potential therapeutic target.

The contribution of 700,000 ORF sequence tags to the definition of the human transcriptome

Open reading frame expressed sequences tags (ORESTES) differ from conventional ESTs by providing sequence data from the central protein coding portion of transcripts. We generated a total of 696,745 ORESTES sequences from 24 human tissues and used a subset of the data that correspond to a set of 15,095 full-length mRNAs as a means of assessing the efficiency of the strategy and its potential contribution to the definition of the human transcriptome. We estimate that ORESTES sampled over 80% of all highly and moderately expressed, and between 40% and 50% of rarely expressed, human genes. In our most thoroughly sequenced tissue, the breast, the 130,000 ORESTES generated are derived from transcripts from an estimated 70% of all genes expressed in that tissue, with an equally efficient representation of both highly and poorly expressed genes. In this respect, we find that the capacity of the ORESTES strategy both for gene discovery and shotgun transcript sequence generation significantly exceeds that of conventional ESTs. The distribution of ORESTES is such that many human transcripts are now represented by a scaffold of partial sequences distributed along the length of each gene product. The experimental joining of the scaffold components, by reverse transcription-PCR, represents a direct route to transcript finishing that may represent a useful alternative to full-length cDNA cloning.

TSG-14 transgenic mice have improved survival to endotoxemia and to CLP-induced sepsis

Tumor necrosis factor-stimulated gene 14 (TSG-14)/PTX3 was identified originally as a TNF-alpha and IL-1beta-stimulated gene from normal, human foreskin fibroblasts and vascular endothelial cells, respectively. TSG-14 gene encodes a 42-kDa-secreted glycoprotein with a carboxy-terminal half that shares homology with the entire sequence of C-reactive protein (CRP) and serum amyloid P component (SAP), acute-phase proteins of the pentraxin family. Some experimental evidence suggests that TSG-14 plays a role in inflammation, yet its function and mechanism of action remain unclear. We have generated transgenic mice that overexpress the murine TSG-14 gene under the control of its own promoter. From eight transgenic founders, two lineages were derived and better characterized: Tg2 and Tg4, carrying two and four copies of the transgene, respectively. TSG-14 transgenic mice were found to be more resistant to the endotoxic shock induced by LPS and to the polymicrobial sepsis caused by cecal ligation and puncture (CLP). Moreover, macrophages derived from the transgenic mice produced higher amounts of nitric oxide in response to IFN-gamma, TNF-alpha, and LPS as compared with macrophages from wild-type animals, and the augmented response appears to be the consequence of a higher responsiveness of transgenic macrophages to IFN-gamma. The data shown here are the first in vivo evidence of the involvement of TSG-14 in the inflammatory process and suggest a role for TSG-14 in the defense against bacterial infections.

Schistosoma mansoni egg-induced hepatic granulomas in mice deficient for the interferon-gamma receptor have altered populations of macrophages, lymphocytes and connective tissue cells

Systemic production and mobilization of inflammatory cells and formation of hepatic periovular granulomas were studied in Schistosoma mansoni-infected mice with deficient interferon gamma (IFN-gamma) receptor (IFN-gammaR(o/o)). The impaired IFN-gamma signaling did not cause a significant modification of the overall kinetics of inflammatory cells, but mutant mice developed smaller hepatic periovular granulomas with a two-fold reduction in all the cell lineages. In granulomas of normal mice, the fully differentiated macrophages were progressively predominant, whilst in IFN-gammaR(o/o) mice, the granulomas contained a higher percentage of immature and proliferating monocytes. Granulomas of IFN-gammaR(o/o) mice had an enhanced and accelerated fibrotic reaction, corresponding to an increased content of proliferative and activated connective tissue cells. Simultaneously, their granulomas had an increased ratio of T over B cells, with an increase in CD8(+) and a reduction in CD4(+) T cells. The functional IFN-gamma receptor was not required for initial recruitment of monocytes and lymphocytes into granulomas, but it was necessary for the maturation of macrophages, upregulation of major histocompatibility class 2 (MHC-II) expression and consequent stimulation of lymphocyte subpopulations depending upon the MHC-II-mediated antigen presentation.

Sodium salicylate induces the expression of the immunophilin FKBP51 and biglycan genes and inhibits p34cdc2 mRNA both in vitro and in vivo

One of the mechanisms proposed to explain the anti-inflammatory activity of sodium salicylate (NaSal) is based, at least in part, on its ability to inhibit nuclear factor-kappaB activation and inhibition of nuclear factor-kappaB-dependent gene expression. On the other hand, little is known about the ability of NaSal to activate gene expression. By differential display reverse transcription polymerase chain reaction, we identified several genes that are modulated upon treatment of mouse fibroblasts with NaSal. From the various cDNA fragments recovered from autoradiograms, we found that NaSal can increase the levels of mRNA for biglycan, the mouse homologue of the human eIF-3 p47 unit, and immunophilin FKBP51. NaSal-induced expression of these genes was time- and dose-dependent. Moreover, FKBP51 gene expression was augmented in vivo, in mice treated orally or intraperitoneally with NaSal. We also found that treating cells with NaSal can inhibit the expression of the p34(cdc2) kinase. The impact this inhibition on cell cycle was evaluated by measuring the content of DNA during the cell cycle. Treatment of cells with NaSal led to a G(2)/M arrest. By investigating the signaling events that regulate the expression of these genes and their biological activities, we can contribute to the understanding of the mechanism of NaSal.

Shotgun sequencing of the human transcriptome with ORF expressed sequence tags

Theoretical considerations predict that amplification of expressed gene transcripts by reverse transcription-PCR using arbitrarily chosen primers will result in the preferential amplification of the central portion of the transcript. Systematic, high-throughput sequencing of such products would result in an expressed sequence tag (EST) database consisting of central, generally coding regions of expressed genes. Such a database would add significant value to existing public EST databases, which consist mostly of sequences derived from the extremities of cDNAs, and facilitate the construction of contigs of transcript sequences. We tested our predictions, creating a database of 10,000 sequences from human breast tumors. The data confirmed the central distribution of the sequences, the significant normalization of the sequence population, the frequent extension of contigs composed of existing human ESTs, and the identification of a series of potentially important homologues of known genes. This approach should make a significant contribution to the early identification of important human genes, the deciphering of the draft human genome sequence currently being compiled, and the shotgun sequencing of the human transcriptome.

Differential regulation of TSG-14 expression in murine fibroblasts and peritoneal macrophages

Tumor necrosis factor (TNF)-stimulated gene 14 (TSG-14, also termed PTX3) encodes a secreted glycoprotein whose carboxy-terminal half shares sequence similarity with the pentraxin family of acute phase proteins (C-reactive protein and serum amyloid P component). We compared TSG-14 mRNA expression in cultures of murine BALB/c 3T3 fibroblasts and thioglycollate-elicited peritoneal macrophages. TNF and interleukin-1 (IL-1) potently induced TSG-14 expression in 3T3 fibroblasts but not in peritoneal macrophages. Lipopolysaccharide (LPS) elicited TSG-14 expression in both cell types, but induction in 3T3 cells and macrophages showed several distinct characteristics. Whereas in 3T3 fibroblasts TSG-14 mRNA was rapidly up-regulated by LPS, expression in macrophages was substantially delayed. Furthermore, cycloheximide greatly reduced LPS-induced TSG-14 mRNA up-regulation in macrophages but not in 3T3 cells. Finally, interferon-gamma (IFN-gamma; but not IFN-alpha/beta) inhibited LPS-induced TSG-14 expression in macrophages and not in 3T3 fibroblasts. The antioxidant pyrrolidine dithiocarbamate inhibited LPS-induced nuclear factor-kappaB (NF-kappaB) activation and TSG-14 expression in macrophages. In contrast, IFN-gamma did not inhibit NF-kappaB function as measured by IkappaB-alpha and IkappaB-beta degradation, IkappaB-alpha resynthesis, or electrophoretic mobility shift analysis. Inhibition of LPS-induced TSG-14 mRNA expression by IFN-gamma in macrophages was also observed in the presence of cycloheximide and in cells from STAT1 null mice, suggesting that IFN-gamma inhibits TSG-14 expression through an unconventional mechanism.

Identification and partial characterization of FRAG-6, a novel interferon-stimulated gene that is expressed in an IRF-1-INDEPENDENT manner

In order to identify new interferon-stimulated genes that could help in the better understanding of the mechanism of action of interferons (IFNs), we decided to compare, by differential display RT-PCR (DDRT-PCR), the pattern of gene expression between IFN-alpha treated and untreated mouse embryonic fibroblasts (MEFs). Here we describe the initial characterization of a new cDNA fragment, named FRAG-6, that is expressed only upon IFN stimulation. The IFN-induced expression of this new gene can be observed in both wild-type and IRF-1-deficient MEF. FRAG-6 cDNA hybridizes with an mRNA of 6-9 kb that is induced by IFNs in a time-dependent manner. Analysis of the cloned nucleotide sequence revealed a 174 amino acid (aa) open reading frame (ORF) contained within the 576 bp. No significant homology with known nucleotide or protein sequences was observed. FRAG-6 is induced in vitro upon treatment of wild type or IRF-1-null cells with IFN-alpha or -gamma, but not with TNF or IL-1. Treatment of mice with imiquimod, a potent inducer of IFN, led to induced expression of FRAG-6 mRNA in various organs from wild type or IRF-1-deficient mice, but not from STAT-1 or type I IFN receptor deficient animals. Our results demonstrate that FRAG-6 mRNA induction by interferons is IRF-1-independent and it is likely to be activated by the JAK/STAT pathway. Further characterization of FRAG-6 will help us in the understanding of the mechanism of action of IFNs.

Expression of serum amyloid A3 mRNA by inflammatory macrophages exposed to membrane glycoconjugates from Trypanosoma cruzi

Differential display reverse transcriptase-polymerase chain reaction (PCR) was used to identify genes expressed by murine macrophages exposed to glycosylphosphatidylinositol-anchored mucin-like glycoproteins isolated from Trypanosoma cruzi trypomastigotes. Among the different PCR product bands identified in the differential display gel, one showed high homology with the serum amyloid A3 protein (SAA3). Northern blot assays showed augmentation of SAA3 mRNA expression by inflammatory macrophages exposed to live trypomastigotes or parasite glycolipids, as compared to unstimulated macrophages. Our results also showed the expression of SAA3 mRNA, in liver and heart from animals in the acute phase of Chagas disease. It is important that expression of SAA3 mRNA was closely associated with tissue parasitism and presence of inflammatory cells. Together, our findings indicate the possible involvement of SAA3 protein on immunopathology of Chagas disease and establish a new infectious disease model to study the pathophysiological role of this acute-phase protein.

Application of the differential display RT-PCR strategy for the identification of inflammation-related mouse genes

The inflammatory response elicited by various stimuli such as microbial products or cytokines is determined by differences in the pattern of cellular gene expression. We have used the differential display RT-PCR (DDRT-PCR) strategy to identify mRNAs that are differentially expressed in various murine cell types stimulated with pro-inflammatory cytokines, microbial products or anti-inflammatory drugs. Mouse embryonic fibroblasts (MEFs) were treated with IFNs, TNF, or sodium salicylate. Also, peritoneal macrophages from C3H/Hej mice were stimulated with T. cruzi-derived GPI-mucin and/or IFN-gamma. After DDRT-PCR, various cDNA fragments that were differentially represented on the sequencing gel were recovered, cloned and sequenced. Here, we describe a summary of several experiments and show that, when 16 of a total of 28 recovered fragments were tested for differential expression, 5 (31%) were found to represent mRNAs whose steady-state levels are indeed modulated by the original stimuli. Some of the identified cDNAs encode for known proteins that were not previously associated with the inflammatory process triggered by the original stimuli. Other cDNA fragments (8 of 21 sequences, or 38%) showed no significant homology with known sequences and represent new mouse genes whose characterization might contribute to our understanding of inflammation. In conclusion, DDRT-PCR has proven to be a potent technology that will allow us to identify genes that are differentially expressed when cells are subjected to changes in culture conditions or isolated from different organs.

The immune response modifier imiquimod requires STAT-1 for induction of interferon, interferon-stimulated genes, and interleukin-6

Imiquimod is an oral inducer of interferon (IFN) and several other proinflammatory cytokines and has been successfully used topically as an antiviral agent for the treatment of genital warts. We have investigated the molecular mechanisms by which imiquimod induces the expression of IFNs, IFN-stimulated genes (ISGs), and proinflammatory cytokines in vivo, using mice deficient in various components of the IFN signaling system. Mice deficient in the transcription factor interferon regulatory factor 1 (IRF-1) or in the serine/threonine protein kinase PKR responded normally to imiquimod, producing high levels of circulating IFN and induction of several ISGs. On the other hand, when mice deficient in STAT-1 were treated, a 32-fold reduction in the level of circulating IFN was observed, together with a lack of induction of 2-5 oligo adenylate synthetase (2-5 OAS) and IRF-1 genes. Interestingly, there was also a lack of induction of interleukin-6 (IL-6) gene expression, although tumor necrosis factor was induced and readily detected in serum. In mice deficient in the type I IFN receptor, imiquimod induced levels of IFN similar to those in control mice, but again, neither 2-5 OAS, IRF-1, nor IL-6 genes were induced in mutant mice. Our results suggest that STAT-1 plays a critical role in the mechanism of gene activation by imiquimod. Moreover, induction of IL-6 gene expression appears to be dependent on components of the IFN signaling cascade.

Mice lacking the gamma interferon receptor have an impaired granulomatous reaction to Schistosoma mansoni infection

The egg-induced granulomatous reaction in Schistosoma mansoni-infected individuals develops within the portal system of the liver and is the major pathological finding in schistosomiasis. We have infected mice lacking the gamma interferon (IFN-gamma) receptor with S. mansoni larvae and studied the development of hepatic granulomas in these mutant mice in comparison to that in control wild-type mice. In the absence of IFN-gamma activity, a dramatic reduction in the size and architecture of the granuloma was observed. Granulomas from mutant mice were smaller than those from the control group and showed a significant reduction in the number of infiltrating inflammatory cells. Moreover, they appear to prematurely progress to the chronic phase of the reaction at a time when the control group still has acute inflammation. Our data suggests a pivotal role for IFN-gamma in the early events of the granulomatous reaction in vivo.

Regulation of LMP2 and TAP1 genes by IRF-1 explains the paucity of CD8+ T cells in IRF-1-/- mice

The TAP1 and LMP2 genes are central for class I MHC function and share a common promoter. Here, we analyze the molecular mechanism of IFN gamma up-regulation of TAP1 and LMP2. In vivo footprinting indicates IFN gamma up-regulates protein-DNA contacts at an IRF-E that is essential for the up-regulation of TAP1 and LMP2 by IFN gamma. Gel shift analysis indicates that this site binds IRF-1. The expression of TAP1 and LMP2 are both greatly reduced in IRF-1-deficient mice. Surface class I MHC as well as CD8+ T cells are reduced in IRF-1-/- mice. The role of IRF-1 in the regulation of TAP1 and LMP2 suggests a mechanism for the antiviral properties of IRF-1 and the unexpected deficiency of CD8+ T cells observed in IRF-1-/- mice.

Deficient signaling in mice devoid of double-stranded RNA-dependent protein kinase

Double-stranded RNA-dependent protein kinase (PKR) has been implicated in interferon (IFN) induction, antiviral response and tumor suppression. We have generated mice devoid of functional PKR (Pkr%). Although the mice are physically normal and the induction of type I IFN genes by poly(I).poly(C) (pIC) and virus is unimpaired, the antiviral response induced by IFN-gamma and pIC was diminished. However, in embryo fibroblasts from Pkr knockout mice, the induction of type I IFN as well as the activation of NF-kappa B by pIC, were strongly impaired but restored by priming with IFN. Thus, PKR is not directly essential for responses to pIC, and a pIC-responsive system independent of PKR is induced by IFN. No evidence of the tumor suppressor activity of PKR was demonstrated.

Interferon regulatory factor 1 is required for mouse Gbp gene activation by gamma interferon

Full-scale transcriptional activation of the mouse Gbp genes by gamma interferon (IFN-gamma) requires protein synthesis in embryonic fibroblasts. Although the Gbp-1 and Gbp-2 promoters contain binding sites for transcription factors Stat1 and IFN regulatory factor 1 (IRF-1), deletion analysis revealed that the Stat1 binding site is dispensable for IFN-gamma inducibility of Gbp promoter constructs in transfected fibroblasts. However, activation of the mouse Gbp promoter by IFN-gamma requires transcription factor IRF-1. Transient overexpression of IRF-1 cDNA in mouse fibroblasts resulted in high-level expression of Gbp promoter constructs. Unlike wild-type cells, IRF-1% embryonic stem cells lacking functional transcription factor IRF-1 contained very low levels of Gbp transcripts that were not increased in response to differentiation or treatment with IFN-gamma. Treatment of IRF-1% mice with IFN-gamma resulted in barely detectable levels of Gbp RNA in spleens, lungs, and livers, whereas such treatment induced high levels of Gbp RNA in the organs of wild-type mice. These observations suggest two alternative pathways for transcriptional induction of genes in response to IFN-gamma: immediate response that results from activation of preformed Stat1 and delayed response that results from induced de novo synthesis of transcription factor IRF-1.

Mice devoid of interferon regulatory factor 1 (IRF-1) show normal expression of type I interferon genes

The transcription factor interferon regulatory factor 1 (IRF-1) binds tightly to the interferon (IFN)-beta promoter and has been implicated in the induction of type I IFNs. We generated mice devoid of functional IRF-1 by targeted gene disruption. As reported by others, IRF-1-deficient mice showed a discrete phenotype: the CD4/CD8 ratio was increased and IFN-gamma-induced levels of macrophage iNO synthase mRNA were strongly diminished. However, type I IFN induction in vivo by virus or double-stranded RNA was unimpaired, as evidenced by serum IFN titers and IFN mRNA levels in spleen, liver and lung. There was also no impairment in the response of type I IFN-inducible genes. Therefore, IRF-1 is not essential for these processes in vivo.

Functional role of type I and type II interferons in antiviral defense

Mice lacking the known subunit of the type I interferon (IFN) receptor were completely unresponsive to type I IFNs, suggesting that this receptor chain is essential for type I IFN-mediated signal transduction. These mice showed no overt anomalies but were unable to cope with viral infections, despite otherwise normal immune responses. Comparison of mice lacking either type I or type II IFN receptors showed that, at least in response to some viruses, both IFN systems are essential for antiviral defense and are functionally nonredundant.

Induction of type I interferon genes and interferon-inducible genes in embryonal stem cells devoid of interferon regulatory factor 1

Overexpression of interferon regulatory factor 1 (IRF-1) can induce expression of the interferon (IFN) beta gene, at least in certain cells. A role of IRF-1 in the activation of IFN-alpha genes has also been claimed. We have generated embryonal stem cells in which both IRF-1 alleles were disrupted. In undifferentiated embryonal stem cells, virus-induced levels of IFN-alpha RNA were similar for wild-type and IRF-1%, and there was little induction of IFN-beta RNA in either cell type. In 8-day differentiated cells, the levels of virus-induced IFN-beta RNA, but not of IFN-alpha RNA, were about 10-fold higher than in undifferentiated cells and only slightly higher in wild-type than in IRF-1% cells. Thus, although IRF-1 at high levels may elicit or augment induction of IFN genes under certain circumstances, it is not essential for IFN gene induction by virus. Lack of IRF-1 had no effect on the IFN-induced expression levels of the IFN-inducible genes tested; however, there was little or no constitutive expression of (2'-5')oligoadenylate synthetase in IRF-1% embryonal stem cells, in contrast to wild-type cells.

Critical role of a common transcription factor, IRF-1, in the regulation of IFN-beta and IFN-inducible genes

Interferon regulatory factor 1 (IRF-1) is a protein that binds to cis-elements within the promoter of interferon (IFN)-beta and some IFN-inducible genes. We used a human fibroblast line, GM-637, to generate stable transfectants constitutively expressing IRF-1 mRNA in either the sense or antisense orientation. Upon induction with poly-(I).poly(C) or Newcastle disease virus, cells expressing sense IRF-1 mRNA produced significantly higher levels of IFN-beta mRNA and protein than control cells, whereas cells expressing antisense IRF-1 mRNA produced little or no IFN-beta mRNA and protein. Furthermore, clear differences were seen among the transfectants in the level of expression of two IFN-induced genes (2'-5'-oligoadenylate synthetase and class I HLA). Our data show that IRF-1 is essential for the induced expression of the IFN-beta gene. The results also indicate an important role of IRF-1 in the expression of IFN-inducible genes and suggest a role for IRF-1 in many other cytokine actions.

Induction of the transcription factor IRF-1 and interferon-beta mRNAs by cytokines and activators of second-messenger pathways

Nuclear protein IRF-1 (interferon regulatory factor 1) was earlier shown to bind to cis-acting regulatory elements present on interferon (IFN)-alpha/beta genes and some IFN-inducible genes. Here we show that in both human FS-4 and murine L929 cells, steady-state levels of IRF-1 mRNA were increased by treatment with tumor necrosis factor (TNF), interleukin 1 (IL-1), poly(I).poly(C), or IFN-beta. IRF-1 mRNA induction was also demonstrated in cells treated with calcium ionophore A23187 or with phorbol 12-myristate 13-acetate, but not with epidermal growth factor, dibutyryl-cAMP, or the adenylate cyclase activator forskolin. To determine whether stimulation of IRF-1 mRNA levels correlates with IFN-beta induction, we compared IRF-1 and IFN-beta mRNA levels in cells exposed to various stimuli. In L929 cells, treatment with poly(I).poly(C) under conditions that failed to induce significant levels of IFN-beta mRNA led to a very low induction of IRF-1 mRNA, but "priming" cells with IFN prior to the addition of poly(I).poly(C) greatly increased both IRF-1 and IFN-beta mRNAs. In FS-4 cells an increase in IFN-beta mRNA (examined by the polymerase chain reaction) was seen after treatment with TNF, IL-1, A23187, or poly(I).poly(C), but not with IFN-beta, epidermal growth factor, dibutyryl-cAMP, or forskolin. Thus, all treatments that increased steady-state levels of IFN-beta mRNA also enhanced IRF-1 mRNA levels. However, treatment with IFN-beta, which caused a marked stimulation in IRF-1 mRNA, failed to produce a detectable increase in IFN-beta mRNA. It appears that IRF-1 may be necessary but not sufficient for IFN-beta induction. The ability of TNF and IL-1 to increase both IRF-1 and IFN-beta mRNAs may be responsible for some similarities in the actions of TNF, IL-1, and the IFNs.

Tumor necrosis factor acts synergistically with autocrine interferon-beta and increases interferon-beta mRNA levels in human fibroblasts

Medium of untreated human FS-4 foreskin fibroblasts contained a factor which, upon the addition of exogenous tumor necrosis factor (TNF), inhibited encephalomyocarditis virus replication when neither medium alone nor TNF alone were effective. This antiviral activity was abolished by a monoclonal antibody to human interferon (IFN)-beta, suggesting that the active component in the medium from untreated FS-4 cells was IFN-beta, present at subeffective concentrations. In addition, we show that untreated FS-4 cells contain IFN-beta mRNA, demonstrable by the highly sensitive polymerase chain reaction after reverse transcription. Treatment of FS-4 cells with TNF produced an approximately 16-fold increase in the steady-state level of IFN-beta mRNA. Our results support the conclusion that autocrine IFN-beta is secreted by untreated normal fibroblasts and that TNF can enhance the production of autocrine IFN-beta by increasing the level of IFN-beta mRNA. Our study also demonstrates that subeffective concentrations of autocrine IFN-beta, which escape detection in conventional assays, are sufficient to produce a strong synergistic action with TNF.

Antigenic characterization of human interferon derived from amniotic membranes induced by virus

The presence of protein(s) with interferon (IFN)-like activity in culture fluid from human amniotic membranes induced by viruses has been described by different groups. However, the antigenic structure of this protein is controversial. Here we report the presence of IFN activity in supernatants of human amniotic membranes induced by Sendai virus. The major component responsible for this antiviral activity seems to be the classical IFN-beta. However, we were able to demonstrate the presence of a protein fraction with antiviral activity that does not bind to an affinity column for IFN-beta. The antiviral activity of this unbound fraction cannot be neutralized by antibodies to IFN-alpha, -beta, gamma, or by a mixture of them. We called this unbound fraction IFN-AM. We also report the development of a monoclonal antibody that does not neutralize the antiviral activity of IFN-alpha or IFN-beta but reduces the antiviral activity of a partially purified preparation of Sendai virus-induced amniotic membrane supernatant. These observations suggest that the IFN-AM (the unbound fraction that lacks reactivity with antibodies against known IFNs) contains a unique antigenic determinant that is not present, or, if so, is not located at the functional domain of IFN-alpha, -beta, or -gamma.

Interleukin 2-dependent and interleukin 2-independent pathways of regulation of thymocyte function by interleukin 6

Recombinant human interleukin 6 (IL-6), also termed B-cell-stimulatory factor 2 (BSF-2) or interferon-beta 2, was found to stimulate the proliferation of mouse thymocytes costimulated with phytohemagglutinin (PHA). In addition, IL-6 synergistically enhanced the stimulation of thymocyte proliferation by recombinant human interleukin 1 (IL-1) or interleukin 2 (IL-2). Mature thymocytes lacking peanut agglutinin receptor are the main target of IL-6 action. Incubation of thymocytes with IL-6 in the presence of PHA resulted in an increased expression of the IL-2 receptor (IL-2R) as demonstrated by flow cytometry. Monoclonal antibody specific for the p55 chain of the murine IL-2R significantly reduced IL-6-stimulated thymocyte proliferation in the presence of the optimal concentration of PHA. However, the same monoclonal antibody failed to reduce IL-6-driven thymocyte proliferation in the presence of a suboptimal PHA concentration, suggesting that IL-6 stimulates thymocyte proliferation by way of IL-2-dependent and IL-2-independent pathways. These results indicate that, in addition to its earlier demonstrated ability to promote B-cell differentiation and growth, IL-6 also acts as a growth regulator in cells of the T-lymphocyte lineage. IL-6 is emerging as an important regulatory cytokine with multiple actions on immune functions.

Antiviral action of tumor necrosis factor in human fibroblasts is not mediated by B cell stimulatory factor 2/IFN-beta 2, and is inhibited by specific antibodies to IFN-beta

A protein termed IFN-beta 2, originally described on the basis of antiviral activity and antigenic cross-reactivity with the classical IFN-beta, is now known to be identical with the independently isolated B cell stimulatory factor (BSF-2). Earlier it was suggested that IFN-beta 2 (i.e., BSF-2) mediates the antiviral action of TNF in human fibroblasts. We examined Escherichia coli-derived recombinant preparations of human IFN-beta and BSF-2 for antiviral activity and plasmacytoma growth factor (PCT-GF) activity. IFN-beta had antiviral activity but showed no PCT-GF activity. BSF-2 showed potent PCT-GF activity but lacked antiviral activity. Antiviral activity of IFN-beta was neutralized by polyclonal antibodies and mAb to IFN-beta, but not by antibody to rBSF-2. PCT-GF activity of BSF-2 was neutralized by antibody to rBSF-2, but not by antibodies neutralizing the antiviral action of IFN-beta. Five mAb and a polyclonal antibody to human IFN-beta failed to react with BSF-2 in a solid phase RIA and antibody to BSF-2 did not react with IFN-beta. PCT-GF activity in supernatants of human FS-4 fibroblasts stimulated with TNF, IL-1 or poly(I).poly(C) was neutralized by antibody to rBSF-2, but not by antibodies neutralizing the antiviral activity of IFN-beta. Finally, the antiviral activity of TNF in FS-4 cultures was neutralized by antibodies to IFN-beta but not by antibodies to BSF-2. Taken together, these results support the view that the antiviral action of TNF in human fibroblasts is mediated by IFN-beta, and not by BSF-2/IFN-beta 2 that apparently lacks significant antiviral activity.

Antiviral action of tumor necrosis factor in human fibroblasts is not mediated by B cell stimulatory factor 2/IFN-beta 2, and is inhibited by specific antibodies to IFN-beta

A protein termed IFN-beta 2, originally described on the basis of antiviral activity and antigenic cross-reactivity with the classical IFN-beta, is now known to be identical with the independently isolated B cell stimulatory factor (BSF-2). Earlier it was suggested that IFN-beta 2 (i.e., BSF-2) mediates the antiviral action of TNF in human fibroblasts. We examined Escherichia coli-derived recombinant preparations of human IFN-beta and BSF-2 for antiviral activity and plasmacytoma growth factor (PCT-GF) activity. IFN-beta had antiviral activity but showed no PCT-GF activity. BSF-2 showed potent PCT-GF activity but lacked antiviral activity. Antiviral activity of IFN-beta was neutralized by polyclonal antibodies and mAb to IFN-beta, but not by antibody to rBSF-2. PCT-GF activity of BSF-2 was neutralized by antibody to rBSF-2, but not by antibodies neutralizing the antiviral action of IFN-beta. Five mAb and a polyclonal antibody to human IFN-beta failed to react with BSF-2 in a solid phase RIA and antibody to BSF-2 did not react with IFN-beta. PCT-GF activity in supernatants of human FS-4 fibroblasts stimulated with TNF, IL-1 or poly(I).poly(C) was neutralized by antibody to rBSF-2, but not by antibodies neutralizing the antiviral activity of IFN-beta. Finally, the antiviral activity of TNF in FS-4 cultures was neutralized by antibodies to IFN-beta but not by antibodies to BSF-2. Taken together, these results support the view that the antiviral action of TNF in human fibroblasts is mediated by IFN-beta, and not by BSF-2/IFN-beta 2 that apparently lacks significant antiviral activity.