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Biomedical subjects

B Beutler

Publications and source records attributed to B Beutler.

At least 109 records · Page 6Linked to original sources
PubMed1989

Cachectin/tumor necrosis factor-alpha formation in human decidua. Potential role of cytokines in infection-induced preterm labor.

This study was conducted as part of an investigation to evaluate the hypothesis that bacterial toxins (LPS or lipoteichoic acid), acting on macrophage-like uterine decidua to cause increased formation of cytokines, may be involved in the pathogenesis of infection-associated preterm labor. We found that cachectin/tumor necrosis factor-alpha (TNF-alpha) was synthesized and secreted into the culture medium by human decidual cells and explants in response to treatment with LPS. LPS treatment also caused an increase in PGF2 alpha production by decidual cells and explants. In amnion cells in monolayer culture, TNF-alpha stimulated PGE2 formation, and TNF-alpha was cytostatic (inhibited [3H]thymidine incorporation into DNA) but not cytolytic in amnion cells. TNF-alpha was not detectable (less than 0.34 ng/ml) in the amniotic fluid of normal pregnancies at midtrimester or at term before or after the onset of labor (n = 44); but TNF-alpha was present at concentrations between 2.8 and 22.3 ng/ml in amniotic fluids of 4 of 20 pregnancies with intact membranes complicated by preterm labor (less than 34 wk gestational age). LPS was present in 10 of the 20 amniotic fluids of preterm labor pregnancies, including all four in which TNF-alpha was present. Bacteria were identified in only one of the four LPS-positive, TNF-alpha-positive fluids. Cytokine formation in macrophage-like decidua may serve a fundamental role in the pathogenesis of preterm labor, including increased prostaglandin formation and premature rupture of the membranes.

Amniotic Fluid↗
PubMed1989

Tumor necrosis factor in mediating experimental Haemophilus influenzae type B meningitis.

Tumor necrosis factor (TNF) could possibly be instrumental in mediating injury to the CNS during bacterial meningitis. In CSF of rabbits with meningitis induced with Haemophilus influenzae type b (Hib) lipooligosaccharide (LOS), TNF activity was first detected 45 min after intracisternal (IC) injection of 20 ng Hib LOS and white blood cells (WBC) first appeared 75 min later. The peak TNF activity (45 ng/ml) was observed at 120 min after IC and persisted for 5 h. When 1-2 X 10(7) CFU of Hib was used to induce meningitis, peak CSF TNF activity was comparable with that after 20 ng Hib LOS, but the activity persisted for 14 h. Dexamethasone (DXM) (1 mg/kg per i.v.) given 1 h before or simultaneously with IC Hib LOS reduced significantly TNF activity and meningeal inflammation. Goat anti-human TNF alpha antibodies given IC with 20 ng Hib LOS or 2 X 10(6) CFU of Hib resulted in a significant reduction in CSF TNF concentrations, which was also associated with reduced meningeal inflammation in Hib LOS-inoculated animals. We conclude that TNF participates in mediating meningeal inflammation associated with Hib experimental meningitis, and that DXM, when given before or with Hib LOS, inhibits CSF TNF production and modulates the meningeal inflammatory response.

Animals↗
PubMed1989

Cachectin in tissue injury, shock, and related states.

In the cytokine cascade, a central position is occupied by that molecule known as "cachectin" or "tumor necrosis factor," because this molecule, more than any other, has been shown to mediate the biologic effects of LPS, and to provoke a state of wasting very similar to that observed in cancer cachexia. The history of the isolation of this factor is instructive, because it illustrates the fact that a single mediator may transduce a broad spectrum of biologic effects, and may thus present itself to investigators interested in very disparate phenomena.

Animals↗
PubMed1988

Crystallization of trimeric recombinant human tumor necrosis factor (cachectin).

Crystals of tumor necrosis factor (TNF) have been obtained in two forms. Rhombohedral crystals grow in 1.8 to 2.0 M ammonium sulfite, pH 7.8 at 21 degrees C, and tetragonal crystals grow in 2.6 M magnesium sulfate, pH 5.5 at 25 degrees C. Analysis of TNF by isoelectric focusing under native and denaturing conditions indicates that TNF molecules exist as trimers in solution. The rhombohedral cachectin crystals belong to space group R3 and have unit cell constants a = b = c = 47.65 A and alpha = beta = gamma = 88.1 degrees. Density determinations and the space group indicate that the unit cell contains one 51,000-dalton trimer. These crystals are stable in the x-ray beam and diffract to at least 1.85 A but are apparently twinned by merohedry. The tetragonal crystals are space group P4(3)2(1)2 or its enantiomorph P4(1)2(1)2 and have unit cell constants a = b = 95.08, c = 117.49. The asymmetric unit contains one trimer; the crystals are stable in the x-ray beam and diffract to beyond 3 A.

Crystallization↗
PubMed1988

Assay of a ribonuclease that preferentially hydrolyses mRNAs containing cytokine-derived UA-rich instability sequences.

mRNA molecules encoding a number of inflammatory cytokines, as well as certain proto-oncogenes, contain a conserved UA-exclusive sequence in the 3' untranslated region that confers message instability in vivo. This sequence may comprise a critical regulatory element, governing the level of these mRNA molecules, and determining the efficiency with which they are translated. Through the use of a double-label RNAse assay, we have determined that lysates prepared from mouse macrophages selectively degrade mRNA molecules containing the 3' untranslated UA sequence found in the mRNA encoding human cachectin/TNF. The degree of instability is dependent upon the number of copies of inserted UA sequence present in the target mRNA molecule (a Xenopus beta-globin mRNA). mRNAs containing randomly generated UA sequences are more labile than unmodified globin mRNA, but less susceptible to degradation than mRNAs containing the authentic cachectin-derived sequence. mRNA molecules containing synthetic UG-exclusive sequences are normally stable or protected in vitro. The destruction of UA-containing mRNA is inhibited by random adenylate/uridilate copolymers, but not by guanylate/uridilate copolymers. Boiling or proteinase K treatment destroys the selective nucleolytic activity of macrophage lysates. We propose that the nuclease measured here may serve to regulate cellular levels of mRNA molecules encoding cachectin, other inflammatory cytokines, and certain proto-oncogene products.

Adenine↗
PubMed1988

Cachectin/tumor necrosis factor induces cachexia, anemia, and inflammation.

Cachexia is a potentially lethal syndrome of unknown etiology characterized by anorexia, weight loss, and protein wasting that frequently complicates the treatment of chronic inflammation and cancer. Cachectin/TNF was isolated during the search for a humoral mediator of cachexia and found to stimulate the breakdown of energy stores from adipocytes and myocytes in vitro, but the chronic effects of the monokine in vivo are not known. Sublethal doses of recombinant human cachectin administered twice daily for 7-10 d caused cachexia in rats, as evidenced by reduced food intake, weight loss, and depletion of whole-body lipid and protein stores. Significant anemia is also observed and found to be the result of decreased red blood cell mass, not expanded plasma volume. Leukocytosis and histopathological evidence of tissue injury and inflammation are observed in several organs, including omentum, liver, spleen, and heart. These data suggests that the exposure of the normal host to cachectin is capable of inducing a pathophysiological syndrome of cachexia, anemia, and inflammation similar to that observed during inflammatory states or malignancy.

Anemia↗
PubMed1988

Macrophages secrete a novel heparin-binding protein with inflammatory and neutrophil chemokinetic properties.

We report the identification and purification of a new inflammatory monokine synthesized by the macrophage tumor cell line RAW 264.7 in response to endotoxin. This monokine, which we term "macrophage inflammatory protein" (MIP), is a doublet with an apparent molecular mass of approximately 8,000 daltons on SDS-PAGE but forms aggregates of greater than 2 x 10(6) daltons as assessed by gel filtration. Partial NH2-terminal amino acid sequence data reveal no significant homology with any previously described protein. Although the monokine is anionic under physiological conditions, it is one of two major macrophage-secreted proteins that bind to heparin at high salt concentrations. At 100 ng/ml or greater, MIP is chemokinetic for human polymorphonuclear cells and triggers hydrogen peroxide production. Subcutaneous injection of 10 ng or greater of MIP into footpads of C3H/HeJ mice elicits an inflammatory response, characterized by neutrophil infiltration. These findings suggest that MIP is an endogenous mediator that may play a role in the host responses that occur during endotoxemia and other inflammatory events.

Amino Acid Sequence↗
PubMed1988

Tumor necrosis factor alpha stimulates leukotriene production in vivo.

Tumor necrosis factor alpha, or cachectin (TNF), is a polypeptide mediator with proinflammatory and antitumor actions. It is produced in large amounts by lipopolysaccharide (LPS)-activated macrophages. TNF as well as LPS stimulated the arachidonate cascade leading to the synthesis of leukotrienes (LT) in vivo. Production of endogenous cysteinyl LT was measured in anesthetized rat using the biliary excretion of N-acetyl-LTE4 as an indicator. Infusion of TNF over a 1-h period greatly increased the rate of cysteinyl LT production during the subsequent 3 h. Pretreatment with anti-TNF antibody F(ab')2 fragments prevented enhanced LT generation as well as tachypnea (a sign of the in vivo action of TNF). LT production elicited by TNF was similar to that evoked by infusion of LPS. Our results indicate that lipoxygenase products are involved in the network of pathophysiological events induced by TNF. The proinflammatory and shock-inducing LT may mediate many of the adverse effects of TNF in vivo as well as its antitumor action.

Animals↗
PubMed1988

Restoration of the lipopolysaccharide-responsive phenotype in C3H/HeJ peritoneal macrophage-P388D1 cell hybrids.

The fusion of thioglycollate-elicited peritoneal macrophages from the lipopolysaccharide (LPS)-nonresponsive C3H/HeJ mouse strain to a hypoxanthine phosphoribosyltransferase (HPRT)-negative variant of the murine macrophage cell line P388D1 has resulted in the derivation of eight hybrid clones following HAT selection. Propidium-Iodide staining followed by flow cytometry has demonstrated that the DNA content of the hybrids represents the sum of the parents. Codominant expression of class I antigens from both parental haplotypes is observed in the hybrids. While class II antigens are inducible following a 72-hr induction with gamma interferon-containing supernatants, the amount of each haplotype varies between clones. These hybrids demonstrate Fc-mediated erythrophagocytosis in contrast to P388D1. In distinction to the C3H/HeJ primary peritoneal-macrophage parent, LPS treatment of the hybrids results in the increased release of both interleukin-1 (IL-1) and cachectin/tumor necrosis factor (TNF) into culture supernatants. Therefore, cell fusion has resulted in the stable restoration of the LPS-responsive phenotype in C3H/HeJ macrophage hybrids. These macrophage hybrids should serve as useful models in understanding the regulation of macrophage effector functions in response to environmental stimuli.

Animals↗