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Biomedical subjects

T van der Poll

Publications and source records attributed to T van der Poll.

At least 91 records · Page 5Linked to original sources
PubMed1998

Minimally invasive surgery induces endotoxin-tolerance in the absence of detectable endotoxemia.

Lipopolysaccharide (LPS) tolerance is characterized by an impaired proinflammatory cytokine production upon restimulation of mononuclear cells with LPS. LPS is considered the primary activator for this phenomenon. In response to major injury and extensive abdominal surgery, an immune reaction comparable to LPS tolerance has been described. Therefore, it was investigated whether primary stimuli other than LPS could induce cytokine downregulation. In eight patients who underwent a laparoscopic cholecystectomy, blood was obtained before and after induction of anaesthesia and 2, 6, and 24 hr postoperatively. Ex vivo stimulation of whole blood resulted in a transient reduction (nadir 2 hr postoperatively) of tumor necrosis factor-alpha, interleukin (IL)-1 beta, and interferon-gamma release, while IL-1 receptor antagonist production increased. Stress hormones, LPS-binding protein, and bactericidal/permeability-increasing protein do not seem to be involved. This study shows that minimally invasive surgery, in the absence of endotoxemia, can induce LPS desensitization. These data suggest that prior endotoxemia is not essential for the development of LPS tolerance.

Acute-Phase Proteins↗
PubMed1998

Reduction of circulating secretory phospholipase A2 levels by anti-tumor necrosis factor chimeric monoclonal antibody in patients with severe Crohn's disease. Relation between tumor necrosis factor and secretory phospholipase A2 in healthy humans and in active Crohn's disease.

BACKGROUND: Secretory phospholipase A2 group II (sPLA2-II) has pro-inflammatory effects. The importance of tumor necrosis factor (TNF) for induction of plasma sPLA2-II in humans was studied in two groups of subjects. SUBJECTS: Six healthy volunteers received a single intravenous injection of recombinant human TNF or isotonic saline at random. Ten patients with active Crohn's disease received a single intravenous infusion of an anti-TNF chimeric monoclonal antibody, cA2. RESULTS: TNF infusion in healthy volunteers resulted in an increase of sPLA2-II at 3 h, with a maximal plasma level at 6 h (20.8+/-8.9 ng/ml; P < 0.05). In Crohn's disease base-line sPLA2-II levels were 33.9+/-13.4 ng/ml 24 h after infusion of cA2, 11.0+/-2.9 ng/ml (P < 0.005). Further decrease occurred in all except two patients at 2 weeks. The decrease in plasma sPLA2-II preceded all clinical signs of remission. CONCLUSION: TNF infusion in healthy humans can induce a rapid increase of circulating sPLA2-II, and selective blocking of TNF-alpha with cA2 results in a rapid decrease in sPLA2-II in peripheral blood. These data confirm that TNF has an important role in regulating the release of sPLA2-II in systemic and local inflammatory reactions.

Adult↗
PubMed1998

Serum concentrations of lipopolysaccharide activity-modulating proteins during tuberculosis.

Lipopolysaccharide (LPS) is the principal stimulator of host defense against gram-negative bacteria. LPS-binding protein (LBP), bactericidal/permeability-increasing protein (BPI), and soluble CD14 (sCD14) bind LPS and regulate its toxicity. Lipoarabinomannan, a cell wall component of Mycobacterium tuberculosis, resembles LPS with respect to induction of inflammatory responses through recognition by LBP and sCD14. LBP, BPI, and sCD14 were measured in serum of 124 patients with tuberculosis in various stages of disease, in persons who had been in close contact with patients with contagious pulmonary tuberculosis, and in healthy controls. Levels of these LPS toxicity-regulating proteins were elevated in patients with active tuberculosis compared with those in contacts and controls and declined during treatment. The levels of LBP and sCD14 were higher in patients with fever and anorexia. LPS-regulating proteins may play a role in host defense during tuberculosis, presumably through interaction with lipoarabinomannan.

Acute-Phase Proteins↗
PubMed1998

Lymph of patients with a systemic inflammatory response syndrome inhibits lipopolysaccharide-induced cytokine production.

In patients with systemic inflammatory response syndrome (SIRS), tolerance of peripheral blood mononuclear cells to a second challenge with lipopolysaccharide (LPS) has been described. Thoracic duct lymph transports LPS and represents the extravascular, interstitial fluid compartment of the body. The aim of this study was to determine the capacity of lymph to influence LPS-induced cytokine production in vitro. Thoracic duct lymph was obtained from patients with SIRS and without SIRS (controls). The effect of lymph and simultaneously collected plasma on LPS-induced cytokine production by normal peripheral blood mononuclear cells was assessed. Both lymph and plasma of patients with SIRS reduced LPS-induced tumor necrosis factor-alpha and interleukin-6 production (P < .01); lymph of controls also inhibited cytokine production (P < .01), although to a lesser extent. This study suggests that LPS tolerance may occur both in the intra- and extravascular compartments.

Acute-Phase Proteins↗
PubMed1998

Parenteral nutrition facilitates activation of coagulation but not of fibrinolysis during human endotoxemia.

Venous thrombosis and bacterial infections are common complications of parenteral nutrition. To test the hypothesis that infection facilitates activation of coagulation during parenteral nutrition, healthy subjects were intravenously injected with endotoxin (2 ng/kg) after they had received either 1 week of standard parenteral nutrition (n = 7) or normal enteral feeding (n = 8). Compared with enteral feeding, parenteral nutrition was associated with a selectively enhanced activation of the coagulation system (plasma levels of thrombin-antithrombin III complexes) during endotoxemia. Activation of the fibrinolytic system (plasminogen activator activity, tissue-type plasminogen activator, plasminogen activator inhibitor type 1) proceeded similarly in both study groups. In patients receiving parenteral nutrition, one common complication (bacterial infection) may facilitate the occurrence of another common complication (venous thrombosis) by synergistic stimulation of the coagulation system.

Adult↗
PubMed1998

Erythromycin inhibits tumor necrosis factor alpha and interleukin 6 production induced by heat-killed Streptococcus pneumoniae in whole blood.

To determine the effects of penicillin and erythromycin on cytokine production induced by heat-killed Streptococcus pneumoniae (HKSP), we studied the effects of those drugs on cytokine production induced by S. pneumoniae in human whole blood in vitro and ex vivo. In whole blood in vitro, erythromycin, but not penicillin, caused a dose-dependent decrease in HKSP-induced production of tumor necrosis factor alpha (TNF) and interleukin 6 (IL-6), while the production of IL-10, IL-12, and gamma interferon was inhibited only at the highest erythromycin concentration tested (10(-3) M). The production of TNF and IL-6 in whole blood obtained from healthy subjects after a 30-min infusion of erythromycin (1,000 mg) was lower after ex vivo stimulation with HKSP than that in blood drawn before the infusion. Inhibition of TNF contributed to erythromycin-induced inhibition of IL-6 synthesis. Inhibition of TNF and IL-6 production by erythromycin may have a negative impact on host defense mechanisms during pneumococcal pneumonia.

Adult↗
PubMed1998

Levels of inhibitors of tumor necrosis factor alpha and interleukin 1beta in urine and sera of patients with urosepsis.

The antiinflammatory cytokine response during urosepsis was determined by measurement of concentrations of soluble tumor necrosis factor receptor (sTNFR) types I and II, interleukin 1 receptor antagonist (IL-1ra), soluble IL-1 receptor type II (sIL-1RII), and interleukin 10 in sera and urine of 30 patients with culture-proven urinary tract infections before and 4, 24, 48, and 72 h after initiation of antibiotic therapy and in 20 healthy individuals. In serum, the levels of sTNFR types I and II, IL-1ra, and IL-10 were higher in patients than in controls. In urine, only sTNFR type I and II levels were elevated in patients. The ratios of concentrations of both types of sTNFR in urine to concentrations in serum were higher in patients than in controls. These findings indicate that during urosepsis, the antiinflammatory cytokine response is generated predominantly at the systemic level.

Adult↗
PubMed1998

Tumor necrosis factor and interleukin-1 inhibitors as markers of disease activity of tuberculosis.

Serum concentrations of tumor necrosis factor-alpha (TNF), interleukin (IL)-1beta, and their circulating inhibitors soluble TNF receptor type I (sTNFRI), type II (sTNFRII), IL-1 receptor antagonist (IL-1ra), and soluble IL-1 receptor type II (sIL-1RII) were measured for 123 patients with tuberculosis (TB) in various stages of disease, in persons who had been in close contact with patients with contagious pulmonary TB, and in healthy controls. Levels of sTNFRI, sTNFRII, and IL-1ra, but not of sIL-1RII, were elevated in patients with active TB compared with contacts and controls and declined during treatment. The concentrations of these mediators did not differ between patients with pulmonary and extrapulmonary TB. The levels of sTNFRI and IL-1ra were higher in patients with fever and anorexia. Neither TNF nor IL-beta was detectable. We conclude that serum concentrations of sTNFRs I and II and IL-1ra may serve as markers of disease activity of TB. Sequential measurements of these cytokine inhibitors may be useful in the monitoring of antituberculous therapy.

AIDS-Related Opportunistic Infections↗
PubMed1997

Modulation of cytokine release and neutrophil function by granulocyte colony-stimulating factor during endotoxemia in humans.

In this double-blind, cross-over, placebo-controlled, randomized study, two groups of eight healthy male volunteers were challenged with endotoxin (4 ng/kg) on two occasions, once in conjunction with placebo and once with granulocyte colony-stimulating factor (G-CSF; 5 microg/kg). In group 1, G-CSF was administered intravenously 2 hours before endotoxin challenge; in group 2, G-CSF was administered subcutaneously 24 hours before endotoxin challenge. In group 1, G-CSF significantly enhanced the release of tumor necrosis factor (TNF), interleukin-6 (IL-6), IL-8, IL-1 receptor antagonist (IL-1ra), and soluble TNF receptors. In group 2, G-CSF significantly reduced IL-8 concentrations and modestly attenuated TNF and IL-6 levels. In this group, IL-1ra and soluble TNF receptors were enhanced by G-CSF pretreatment and lipopolysaccharide (LPS)-induced soluble TNF receptor release was further augmented, whereas LPS-induced IL-1ra concentrations remained unaltered. Both pretreatments with G-CSF increased LPS-induced peripheral neutrophilia; the expression of CD11b, CD18, and CD67; and the release of elastase and lactoferrin. Both pretreatments also down-regulated neutrophil L-selectin expression and prevented the endotoxin-induced pulmonary neutrophil accumulation during the first 2 hours after endotoxin challenge. These data indicate that two different pretreatments with G-CSF result in differential effects on LPS-induced cytokine release but similar effects on LPS-induced neutrophil activation and changes in expression of cell surface molecules. Finally, regardless of the effects of G-CSF on LPS-induced cytokine release, G-CSF blocks LPS-induced pulmonary granulocyte accumulation.

Cell Degranulation↗
PubMed1997

Effect of a recombinant dimeric tumor necrosis factor receptor on inflammatory responses to intravenous endotoxin in normal humans.

To determine the role of tumor necrosis factor (TNF) in lipopolysaccharide (LPS)-induced inflammation, 12 healthy subjects received an intravenous injection with LPS (2 ng/kg) preceded by infusion of either a recombinant human dimeric TNF receptor type II-IgG fusion protein (TNFR:Fc; 6 mg/m2; n = 6) or vehicle (n = 6) from -30 minutes to directly before LPS injection. LPS elicited a transient increase in plasma TNF activity, peaking after 1.5 hours (219 +/- 42 pg/mL; P < .05). Infusion of TNFR:Fc completely neutralized endogenous TNF activity. LPS administration was associated with an early activation of fibrinolysis (plasma concentrations of tissue-type plasminogen activator, plasminogen activator activity, and plasmin-alpha2-antiplasmin complexes), followed by inhibition (plasma plasminogen activator inhibitor type I), changes that were completely prevented by TNFR:Fc. By contrast, TNFR:Fc did not influence LPS-induced activation of coagulation (plasma levels of prothrombin fragment F1 + 2 and thrombin-antithrombin III complexes). TNFR:Fc strongly inhibited endothelial cell activation (plasma levels of soluble E-selectin), modestly reduced neutrophil responses (neutrophilia and plasma concentrations of elastase-alpha1-antitrypsin complexes and lactoferrin), but did not affect the release of secretory phospholipase A2 or lipopolysaccharide-binding protein (P > .05). Infusion of TNFR:Fc only (without LPS) in another 6 normal subjects did not induce any inflammatory response. These data indicate that TNF is involved in only some inflammatory responses to intravenous LPS in humans.

Adult↗
PubMed1997

Attenuation of proinflammatory response by recombinant human IL-10 in human endotoxemia: effect of timing of recombinant human IL-10 administration.

To determine the effects of IL-10 on cytokine and granulocyte responses during endotoxemia, two groups of eight healthy male volunteers were challenged with endotoxin (4 ng/kg) on two occasions, once in combination with placebo injection, and once in conjunction with i.v. administered recombinant human IL-10 (rhIL-10) (25 microg/kg). In group 1, rhIL-10 was administered 2 min before endotoxin challenge; in group 2, the intervention was delayed for 1 h after endotoxin administration. rhIL-10 pretreatment reduced the LPS-induced rises in temperature and release of TNF, IL-6, IL-8, and IL-1 receptor antagonist. Endotoxin-induced granulocyte accumulation in lungs, as determined by dynamic granuloscintigrams, was prevented by rhIL-10 pretreatment, whereas granulocyte recruitment in liver and spleen was only modestly reduced. In addition, granulocyte degranulation, as measured by plasma elastase/alpha1-antitrypsin complexes, was blunted significantly by rhIL-10 pretreatment. Post-treatment with rhIL-10 did not influence LPS-induced temperature responses, cytokine release, or granulocyte degranulation. Both rhIL-10 pretreatment and post-treatment reduced LPS-induced cortisol levels. These results indicate that pretreatment with rhIL-10 reduces endotoxin-induced febrile responses, cytokine responses, and granulocyte accumulation in lungs, while in this acute model post-treatment with rhIL-10 exerts limited anti-inflammatory effects.

Adult↗
PubMed1997

Interleukin-10 inhibits activation of coagulation and fibrinolysis during human endotoxemia.

Interleukin-10 (IL-10) has been found to inhibit lipopolysaccharide (LPS)-induced tissue factor expression by monocytes in vitro. To determine the effects of IL-10 on LPS-induced activation of the hemostatic mechanisms in vivo, we performed a placebo-controlled, cross-over study of human endotoxemia. Two groups of eight volunteers were challenged with LPS (4 ng/kg) on two occasions: once in conjunction with placebo, and once with recombinant human IL-10 (rhIL-10; 25 microg/kg). In group 1, placebo or rhIL-10 was given 2 minutes before LPS challenge, group 2 received placebo or rhIL-10 1 hour after LPS administration. Pretreatment with rhIL-10 reduced both LPS-induced activation of the fibrinolytic system (plasma concentrations of tissue type plasminogen activator, plasmin-alpha2-antiplasmin complexes, and D-dimer), and inhibition of fibrinolysis (plasma levels of plasminogen activator inhibitor 1), whereas posttreatment only inhibited the latter response. Both IL-10 pre- and posttreatment attenuated activation of the coagulation system (plasma levels of prothrombin fragment F1 + 2 and thrombin-antithrombin complexes). These results indicate that rhIL-10, besides its well-described inhibitory effects on cytokine release, potently modulates the fibrinolytic system and inhibits the coagulant responses during endotoxemia.

Adult↗
PubMed1997

Epinephrine exerts anticoagulant effects during human endotoxemia.

To determine the effect of a physiologically relevant elevation in the plasma concentrations of epinephrine on the activation of the hemostatic mechanism during endotoxemia, 17 healthy men were studied after intravenous injection of lipopolysaccharide (LPS, 2 ng/kg), while receiving a continuous infusion of epinephrine (30 ng/kg/min) started either 3 h (n = 5) or 24 h (n = 6) before LPS injection, or an infusion of normal saline (n = 6). Activation of the coagulation system (plasma concentrations of thrombin-antithrombin III complexes and prothrombin fragment F1+2) was significantly attenuated in the groups treated with epinephrine when compared with subjects injected with LPS only (P <0.05). Epinephrine enhanced LPS-induced activation of fibrinolysis (plasma levels of tissue-type plasminogen activator and plasmin-alpha2-antiplasmin complexes; P <0.05), but did not influence inhibition of fibrinolysis (plasminogen activator inhibitor type I). In subjects infused with epinephrine, the ratio of maximal activation of coagulation and maximal activation of fibrinolysis was reduced by >50%. Hence, epinephrine exerts antithrombotic effects during endotoxemia by concurrent inhibition of coagulation, and stimulation of fibrinolysis. Epinephrine, whether endogenously produced or administered as a component of treatment, may limit the development of disseminated intravascular coagulation during systemic infection.

Adult↗
PubMed1997

Effects of IL-10 on systemic inflammatory responses during sublethal primate endotoxemia.

IL-10 protects mice from LPS-induced lethality. To determine the effects of IL-10 on LPS-induced inflammatory responses, six Papio anubis baboons were i.v. injected with a sublethal dose of LPS (Salmonella typhimurium; 500 microg/kg) directly preceded by either human rIL-10 (n = 3, 500 microg/kg) or diluent (n = 3). IL-10 strongly inhibited LPS-induced release of TNF, IL-6, IL-8, and IL-12 (all p < 0.05). By contrast, IL-10 did neither influence the activation of the coagulation system (plasma levels of thrombin/antithrombin III complexes), nor the activation of the fibrinolytic system (plasma levels of tissue-type plasminogen activator, plasminogen activator inhibitor type I, and plasmin/alpha 2-antiplasmin complexes). IL-10 modestly attenuated neutrophilic leukocytosis and neutrophil degranulation (plasma concentrations of elastase/alpha1-antitrypsin complexes) (both p < 0.05). Changes in surface TNF receptor expression on circulating granulocytes were not affected by IL-10. These results suggest that during sublethal endotoxemia the predominant anti-inflammatory effect of IL-10 treatment is inhibition of proinflammatory cytokine release.

Animals↗
PubMed1997

Down-regulation of surface receptors for TNF and IL-1 on circulating monocytes and granulocytes during human endotoxemia: effect of neutralization of endotoxin-induced TNF activity by infusion of a recombinant dimeric TNF receptor.

Leukocytes rapidly lose their surface receptors for TNF and IL-1 upon exposure to various stimuli in vitro. We sought to determine by FACS analysis changes in the expression of TNF receptors (TNFR) and type II IL-1R on circulating monocytes and granulocytes during endotoxemia in vivo, and the role of endogenous TNF in these changes. Twelve healthy subjects received an i.v. injection with LPS (2 ng/kg), directly preceded by a 30-min infusion of either a recombinant human dimeric TNFR type II-IgG fusion protein (TNFR:Fc; 6 mg/m2; n = 6) or vehicle (n = 6). LPS administration was associated with decreases in the expression of types I and II TNFR and type II IL-1R on both monocytes and granulocytes. Treatment with TNFR:Fc completely neutralized LPS-induced TNF activity (p < 0.0001 vs LPS only), modestly blunted the decrease in monocyte TNFR (p < 0.05), but did not influence reduced expression of granulocyte TNFR or monocyte/granulocyte type II IL-1R. In separate experiments, rTNF added to whole blood reduced cellular type I and type II TNFR expression by an effect on the type I TNFR; TNF did not (monocytes) decrease or only marginally (granulocytes) decreased type II IL-1R expression. LPS induces down-modulation of monocyte and granulocyte receptors for TNF and IL-1 in humans in vivo. TNF is involved in reduced monocyte TNFR expression during endotoxemia.

Adult↗
PubMed1997

Epinephrine attenuates down-regulation of monocyte tumor necrosis factor receptors during human endotoxemia.

Epinephrine inhibits lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) production by increasing intracellular cAMP concentrations. Because agents that increase cAMP levels can enhance TNF receptor expression in vitro, granulocyte and monocyte TNF receptors were determined by FACS-analysis in 7 normal humans who were receiving a constant 24-h infusion of epinephrine (30 ng/kg/min), and in 15 normal subjects after intravenous injection of LPS (2 ng/kg), while they were receiving a continuous infusion of epinephrine started either 3 h (EPI-3) or 24 h (EPI-24) before LPS injection or an infusion of normal saline (LPS; n = 5 per group). Infusion of epinephrine per se did not influence TNF receptor expression. LPS induced a transient decrease in monocyte TNF receptors and a more sustained decrease in granulocyte TNF receptors (both P < 0.05). EPI-3 partly prevented LPS-induced down-modulation of monocyte TNF receptors (P < 0.05 vs. LPS only), but did not affect LPS-induced down-modulation of granulocyte TNF receptors. EPI-24 had no effect on TNF receptor expression. These data suggest that epinephrine not only influences the bioavailability of TNF by an effect on the production of this proinflammatory cytokine, but also by modulating the expression of its receptors.

Adult↗
PubMed1997

The cytokine-mediated imbalance between coagulant and anticoagulant mechanisms in sepsis and endotoxaemia.

Disseminated intravascular coagulation (DIC) is a frequently occurring complication of sepsis and may contribute to multiple organ failure. More insight into the pathogenesis of this derangement of the coagulation system is necessary to develop more effective therapeutic strategies for this condition. Recently, more detailed knowledge on the pathogenetic pathways involved in DIC has been obtained by the study of models of experimental bacteraemia and endotoxaemia in human subjects and non-human primates. The mechanisms that lead to activation of coagulation, potentiated by the simultaneous depression of physiological inhibitory systems and to impaired function of the fibrinolytic system, are outlined in this review. In addition, the mediatory role of various cytokines in the derangement of coagulation is discussed.

Anticoagulants↗