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Biomedical subjects

V Poli

Publications and source records attributed to V Poli.

At least 55 records · Page 3Linked to original sources
PubMed1996

Impaired neutrophil response and CD4+ T helper cell 1 development in interleukin 6-deficient mice infected with Candida albicans.

To define the role of interleukin (IL)6 in Candida albicans infection, IL-6 deficient mice were assessed for susceptibility to systemic or gastrointestinal infection, as well as for parameters of elicited T helper cell (Th) immunity. IL-6-deficient mice were more susceptible than wild-type mice to either type of infection caused by virulent C. albicans. In response to systemic challenge with a live vaccine strain of yeast, IL-6-deficient mice failed to mount Th1-associated protective immunity, but the resulting Th2-biased response could be redirected to the Th1 phenotype by IL-10 neutralization. Severe impairment of the macrophage and neutrophil response to infection was observed in IL-6-deficient mice, but administration of IL-6 would increase both neutrophil response and resistance to infection. IL-6 seems to oppose the Th2-promoting role of IL-10 in candidiasis, its early regulatory activity involving effects on neutrophil function.

Animals↗
PubMed1996

Six different cytokines that share GP130 as a receptor subunit, induce serum amyloid A and potentiate the induction of interleukin-6 and the activation of the hypothalamus-pituitary-adrenal axis by interleukin-1.

Ciliary neurotrophic factor (CNTF) and interleukin-6 (IL-6) potentiate the elevation of serum corticosterone induced by suboptimal doses of interleukin-1 (IL-1). CNTF also potentiates IL-1-induced serum IL-6. Here, we report that four other cytokines (leukemia inhibitory factor [LIF], oncostatin M [OSM], interleukin-11 and cardiotrophin-1) also potentiated the elevation of serum corticosterone and IL-6 levels induced by IL-1. Furthermore, all the six cytokines studied induced the acute-phase protein serum amyloid A when administered alone. Because these cytokines differ both in structure and in function, but share gp130 as a subunit of their receptors, these results indicate that signaling through gp130 mediates potentiation of IL-1 activities. The potentiation of IL-1-induced serum corticosterone levels is not a consequence of the increased serum IL-6 observed after IL-1 administration. In fact, in IL-6 deficient mice, IL-1 increased serum corticosterone to a level comparable to that observed in wild-type mice. Thus, either endogenous IL-6 does not mediate IL-1-induced corticosterone increase, or its role may be fulfilled by other cytokines. To the extent that gp130-dependent cytokines may serve this role, they may be important feedback regulators of inflammation through the activation of the hypothalamus-pituitary-adrenal axis and the potentiation of acute-phase protein synthesis.

Acute-Phase Reaction↗
PubMed1996

Interleukin (IL)-6 gene expression in the central nervous system is necessary for fever response to lipopolysaccharide or IL-1 beta: a study on IL-6-deficient mice.

Interleukin (IL)-6, IL-1 beta, and tumor necrosis factor alpha (TNF-alpha) are considered to act as endogenous pyrogens. Because of the complex pattern of cross-inductions between these cytokines, the relative role of the central and peripheral production of these cytokines in eliciting the fever response has not yet been clarified. The purpose of this study was to determine the role of IL-6 in the fever response by making use of mice carrying a null mutation in the IL-6 gene. The intraperitoneal injections of lipopolysaccharide (LPS) (50 micrograms/kg) and recombinant murine (rm) IL-1 beta (10 micrograms/kg), respectively, failed to evoke fever response in IL-6-deficient mice, whereas the same doses of LPS and rmIL-1 beta caused fever response in wild-type mice. The fever response could be induced in the IL-6-deficient mice by intracerebroventricular injection of recombinant human (rh) IL-6 (500 ng/mouse), whereas intracerebroventricular injection of rmIL-1 beta (100 ng/mouse) failed to produce fever response in the IL-6-deficient mice. These results suggest that central IL-6 is a necessary component of the fever response to both endogenous (IL-1 beta) and exogenous (LPS) pyrogens in mice and that IL-6 acts downstream from both peripheral and central IL-1 beta.

Animals↗
PubMed1996

C/EBPbeta is required for the late phases of acute phase genes induction in the liver and for tumour necrosis factor-alpha, but not Interleukin-6, regulation.

C/EBPbeta is a leucine-zipper transcription factor believed to play an important role in the control of liver functions, and in particular in the transcriptional regulation of acute phase genes in response to several inflammatory stimuli and to recombinant cytokines. Moreover, this factor has been proposed as an important activator of several cytokine genes. We recently described the generation of mice in which the C/EBPbeta gene has been inactivated by gene targeting, showing that they are viable, but present specific defects in the myeloid and lymphoid compartments. Here we demonstrate that C/EBPbeta does indeed play a role in the transcriptional induction of some, but not all, liver acute phase genes. Activation is in particular defective in C/EBPbeta-deficient mice in the later phases of induction, suggesting that the early phases may be triggered by factors other than C/EBPs. Moreover, IL-6 activation is normal and TNFalpha activation is defective in the mutant mice, indicating a differential role of C/EBPbeta in the control of these two cytokines' production.

Journal Article↗
PubMed1994

Defective inflammatory response in interleukin 6-deficient mice.

Systemic and localized inflammation elicit a number of host responses which include fever, cachexia, hypoglycemia, and major changes in the concentration of liver plasma proteins. Interleukin 6 (IL-6) is considered an important mediator of the inflammatory response, together with IL-1 and tumor necrosis factor alpha (TNF-alpha). The purpose of this study was to unequivocally determine the role of IL-6 in these phenomena making use of IL-6-deficient mice that we have recently generated by gene targeting. We report here that in the absence of IL-6, mice are unable to mount a normal inflammatory response to localized tissue damage generated by turpentine injection. The induction of acute phase proteins is dramatically reduced, mice do not lose body weight and only suffer from mild anorexia and hypoglycemia. In contrast, when systemic inflammation is elicited through the injection of bacterial lipopolysaccharide (LPS), these parameters are altered to the same extent both in wild-type and IL-6-deficient mice, demonstrating that under these conditions IL-6 function is dispensable. Moreover, we show that LPS-treated IL-6-deficient mice produce three times more TNF-alpha than wild-type controls, suggesting that increased TNF-alpha production might be one of the compensatory mechanisms through which a normal response to LPS is achieved in the absence of IL-6. We also show that corticosterone is normally induced in IL-6-deficient mice, demonstrating that IL-6 is not required for the activation of the hypothalamic-pituitary-adrenal axis. Our results reinforce the idea that different patterns of cytokines are involved in systemic and localized tissue damage, and identify IL-6 as an essential mediator of the inflammatory response to localized inflammation.

Acute-Phase Reaction↗
PubMed1994

Interleukin-6 deficient mice are protected from bone loss caused by estrogen depletion.

Interleukin-6 (IL-6) is a multifunctional cytokine whose circulating levels are under physiological conditions below detection, but whose production is rapidly and strongly induced by several pathological and inflammatory stimuli. IL-6 has been implicated in a number of cell functions connected to immunity and hematopoiesis. Recently, it has been proposed to act as a stimulator of osteoclast formation and activity, in particular following estrogen depletion. The purpose of this study was to gain additional insights into the role of IL-6 during development, as well as in physiological and pathological conditions. We report here that IL-6 deficient mice generated by gene targeting are viable and do not present any evident phenotypic abnormality. However, analysis of bone metabolism revealed a specific bone phenotype. IL-6 deficient female mice have a normal amount of trabecular bone, but higher rates of bone turnover than control littermates. Estrogen deficiency induced by ovariectomy causes in wild type animals a significant loss of bone mass together with an increase in bone turnover rates. Strikingly, ovariectomy does not induce any change in either bone mass or bone remodeling rates in the IL-6 deficient mice. These findings indicate that IL-6 plays an important role in the local regulation of bone turnover and, at least in mice, appears to be essential for the bone loss caused by estrogen deficiency.

Animals↗
PubMed1992

Effect of TGF beta on liver genes expression. Antagonistic effect of TGF beta on IL-6-stimulated genes in Hep 3B cells.

The effect of transforming growth factor beta (TGF beta) on the expression of a group of liver genes has been investigated in the hepatoma cell line Hep 3B. TGF beta induces a decrease of the basal level of apolipoprotein A-II (ApoA-II), retinol binding protein (RBP) and alpha-fetoprotein (alpha Fp). Furthermore, TGF beta efficiently antagonizes the IL-6-induction of hemopexin (Hpx) and haptoglobin (Hp) and alpha 1-acid glycoprotein (AGP). These effects of TGF beta are apparently mediated by post-transcriptional mechanism(s). These findings, together with previously reported data on the inhibitory effect of TGF beta on acute phase genes (e.g. ApoA-I and albumin), suggest a role for TGF beta in the regulation of expression of liver genes.

Apolipoprotein A-II↗
PubMed1991

The Interleukin-6-dependent DNA-binding protein gene (transcription factor 5: TCF5) maps to human chromosome 20 and rat chromosome 3, the IL6 receptor locus (IL6R) to human chromosome 1 and rat chromosome 2, and the rat IL6 gene to rat chromosome 4.

Using two panels of somatic cell hybrids segregating either human or rat chromosomes, the gene encoding the interleukin-6-dependent DNA-binding protein, also called liver activator protein (designated transcription factor 5: TCF5), was assigned to human chromosome 20 and to rat chromosome 3. The TCF5 gene might be identical with the NF-IL6 gene. The locus encoding the IL6 receptor gene (IL6R) was localized to human chromosome 1 and rat chromosome 2. An IL6R-like (IL6RL) locus was also assigned to human chromosome 9. In addition, the rat interleukin-6 (IL6) gene was assigned to rat chromosome 4. These mapping data allow one to extend comparison between the rat, mouse, and human gene maps.

Animals↗
PubMed1990

IL-6DBP, a nuclear protein involved in interleukin-6 signal transduction, defines a new family of leucine zipper proteins related to C/EBP.

We analyzed a family of proteins from hepatoma cell nuclei that bind to interleukin-6 responsive elements (IL-6REs) of several acute-phase genes. This family is characterized by leucine zipper domains compatible with that of the CCAAT/enhancer binding protein (C/EBP). A cDNA clone coding for a member of the family, IL-6DBP, was isolated; it is strongly homologous to C/EBP in the region of the basic domain and in the leucine zipper sequence. IL-6DBP and C/EBP can interact in vitro to form heterodimers that bind to DNA with the same specificity as the respective homodimers, and they can interact functionally in vivo. Both the DNA binding activity and the trans-activating capacity of IL-6DBP are induced in hepatoma cells by treatment with IL-6 through a posttranslational mechanism, implicating it as a nuclear target of IL-6 and as a mediator of the IL-6-dependent transcriptional activation of liver genes during the acute-phase response.

Amino Acid Sequence↗
PubMed1989

The analysis of the human hemopexin promoter defines a new class of liver-specific genes.

Hemopexin (Hpx) is a plasma glycoprotein which is expressed only in the liver. It is synthesized at a lower rate in the fetal liver than in the adult, and its level increases during acute infections. As shown here, a fragment of the human hemopexin promoter spanning from positions -130 to +22 relative to the cap site is sufficient to direct cell-specific transcription of a reporter gene. Within this segment a short sequence, located between positions -120 and -104, is responsible for this effect. This positive cis-acting element, the Hpx A site, interacts with a family of nuclear proteins, some of which are present only in hepatoma cells. The potential meaning of these complex DNA-protein interactions and the homology with elements present on the promoter of other liver-specific and acute phase genes are discussed.

Base Sequence↗
PubMed1989

Interleukin 6 induces a liver-specific nuclear protein that binds to the promoter of acute-phase genes.

Interleukin 6 (IL-6) is responsible for a variety of biological effects related to the activation of defenses against infection or inflammation, including the immune response and the acute-phase reaction. Its mechanism of action is unknown. It has recently been shown to induce transcription of several genes encoding acute-phase proteins. Here we describe the identification of an IL-6 responsive element (IL-6RE) present in the promoter of the human hemopexin gene. This element is necessary and sufficient for the IL-6-dependent activation of transcription. The IL-6 effect does not require de novo protein synthesis. A liver-specific nuclear protein (IL-6DBP) binds to the hemopexin IL-6RE as well as to similar sequences on the promoter of other acute-phase genes. IL-6DBP DNA binding activity is induced by IL-6 via a posttranslational mechanism.

Acute-Phase Proteins↗
PubMed1988

Structure of the human hemopexin gene and evidence for intron-mediated evolution.

The human hemopexin gene was isolated and its structure determined. The gene spans approximately 12 kb and is interrupted by nine introns. When the intron/exon pattern was examined with respect to the polypeptide segments they encode, a direct correspondence between exons and the 10 repeating units in the protein was observed. The introns are not randomly placed; they fall in the middle of the region of amino acid sequence homology in strikingly similar locations in 6 of the 10 units and in a symmetrical position in the two halves of the coding sequence. These features strongly support the hypothesis that the gene evolved through intron-mediated duplications of a primordial sequence to a five-exon cluster. A more recent gene duplication led to the present-day gene organization.

Amino Acid Sequence↗
PubMed1985

The primary structure of human hemopexin deduced from cDNA sequence: evidence for internal, repeating homology.

We have cloned and analyzed a cDNA containing the coding sequence for human hemopexin. We have first identified, by immunological screening of 30.000 colonies of a liver cDNA library in the expression vector pEX1, a clone carrying an insert 1170 base pairs long that shows 100% homology with a known human hemopexin peptide. The complete sequence coding for hemopexin was isolated from a liver cDNA library in the vector pAT218. The DNA insert of 1523 base pairs shows an open reading frame coding for 439 amino acids, a 3' noncoding region of 159 nucleotides long, followed by a poly(A) tail. The insert spans the entire coding region and from which the primary structure of the protein was deduced. By computer assisted analysis of the amino acid sequence, it was possible to recognize a core unit, of about 45 amino acids, which is repeated 8 or possibly even 10 fold along the polypeptide chain. This feature suggests that the gene might have evolved through a series of duplications. This characteristic, together with prediction of secondary structure, suggest a rough model for the tridimensional folding that allows some speculations on the function of hemopexin. Blot hybridization of total RNA from human liver with nick translated hemopexin cDNA detected a message of about 1600 nucleotides. Southern blot experiments to identify the hemopexin gene (s) suggest that it is not a large multi-gene family, but that there is only one or at most a few genes in the human genome.

Amino Acid Sequence↗
PubMed1985

Isolated symptomatic lesions of the vertebral artery: cure after surgical repair.

Nine patients with uni-or bilateral stenosis of vertebral arteries, not associated with other lesions of supraaortic trunks are reported. They showed a vertebrobasilar insufficiency syndrome not due to other assessable causes. Seven of them underwent surgical treatment always as reimplantation of the vertebral into the subclavian artery. The procedure was unilateral also in cases with bilateral lesions. In all 7 patients a favourable result was obtained: 5 patients recovered completely and 2 showed a marked improvement. The study demonstrates that the surgical repair of symptomatic unilateral lesions of vertebral arteries is able to cure the vertebrobasilar insufficiency syndrome.

Adult↗
PubMed1976

[Controlled clinical trial of parsalmide in patients with predominantly neuro-anxiety syndromes. Comparison with chlordiazepoxide].

The anxiolytic and tranquillizing effect of a new compound called parsalmide was studied in a group of 20 patients suffering from medium anxiety neurosis. The new drug also possesses anti-inflammatory and analgesic effects. The technique employed was the double blind, between patients, crossover system and chlordiazepoxide was used for comparison purposes. Parsalmide proved to possess an anxiolytic-tranquillizing action comparable to that of chlordiazepoxide and, unlike the latter, was quite free from unpleasant side effects, such as somnolence and asthenia.

Adult↗