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Biomedical subjects

J Pugin

Publications and source records attributed to J Pugin.

18 recordsLinked to original sources
PubMed1996

Proinflammatory activity in bronchoalveolar lavage fluids from patients with ARDS, a prominent role for interleukin-1.

Proinflammatory cytokines such as tumor necrosis factor-alpha (TNF) and interleukin-1beta (IL-1) have been found to be elevated in bronchoalveolar lavage (BAL) fluid and in plasma from patients with acute respiratory distress syndrome (ARDS). In order to measure the balance of proinflammatory cytokines and their inhibitors, we quantified the upregulation of intercellular adhesion molecules (ICAM-1) induced by ARDS BAL fluids in human alveolar type II-like (A459) cells, and defined proinflammatory activity as the amount of ICAM-1 induced by the SAL fluids. Proinflammatory activity was detected in 77% of the SAL fluids sampled during the first week of ARDS, was found maximal during the 3 first days after onset of ARDS, and was significantly greater than in BAL specimens from at risk patients. Blocking experiments with specific inhibitors of TNF and IL-1 added to the BAL fluids indicated that the bioactivity measured was mainly due to IL-1. In contrast, proinflammatory activity of conditioned supernates from endotoxin-treated alveolar macrophages was mostly due to TNF. Using a bioassay that measures balance of cytokines with their inhibitors, our results indicate that the net proinflammatory activity in ARDS BAL fluids is attributable to IL-1 and not to TNF.

Adult↗
PubMed1995

Tumor necrosis factor-alpha and interleukin-1 beta mediate human endothelial cell activation in blood at low endotoxin concentrations.

Activation of endothelial cells by endotoxin (lipopolysaccharide, LPS) may occur through two different pathways. LPS can directly activate endothelial cells through its interaction with soluble CD14 or indirectly via cytokines produced in blood in response to LPS. Substitution of whole blood for plasma apparently increases the endothelial cells responses to LPS by a factor of 1,000, rendering them sensitive to subpicomolar quantities of LPS. This shift in sensitivity is dependent on the presence of monocytes or conditioned plasma from whole blood incubated with small concentrations of LPS. Herein, using agents that block the effects of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta), we demonstrate that TNF-alpha and IL-1 beta are the two LPS-induced cytokines responsible for the activation of endothelial cells, produced in blood in response to picomolar quantities of LPS. Anti-TNF-alpha monoclonal antibodies (mAbs) and IL-1 receptor antagonist separately had partial inhibitory effects. Complete and sustained inhibition of endothelial cell activation was obtained only when the two inhibitors were added together. We conclude that TNF-alpha and IL-1 beta induced in whole blood by picomolar concentrations of LPS mediate endothelial cell activation to these small quantities of LPS and that blocking of both cytokines is necessary to inhibit LPS-induced blood-dependent endothelial cell activation.

Antibodies, Monoclonal↗
PubMed1995

Activation of endothelial cells by endotoxin: direct versus indirect pathways and the role of CD14.

Optimal activation of endothelial cells by nanomolar quantities of endotoxin (lipopolysaccharide, LPS) requires the presence of plasma or serum. We and others have demonstrated that soluble CD14 (sCD14) and LPS binding protein (LBP) were the key plasma proteins mediating endothelial cell responses to LPS. The role of LBP is to transfer LPS to sCD14 and newly formed LPS-sCD14 will in turn activate endothelial cells via an as yet unknown surface receptor. This plasma-dependent pathway of endothelial cells activation is referred as to the direct pathway. However, endothelial cells are in constant contact with whole blood and not only with plasma. In experiments where whole blood was substituted for plasma, we showed that endothelial cells became sensitive to picomolar, rather than nanomolar quantities of LPS. The fact that endothelial cell responses were amplified by the presence of whole blood prompted us to search for the responsible blood cell(s) and mediator(s) for this effect. Blood cell fractionation experiments, experiments with blood from PNH patients and the use of anti-CD14 antibodies pointed to the monocyte as the blood cell responsible for the amplification effect. Moreover, the blood effect could be entirely reproduced by cells from a CD14-expressing cell line, such as calcitriol-differentiated HL-60 cells. Inhibitors to TNF and to IL-1 blocked LPS-induced activation of endothelial cells partially when added separately to whole blood, but abrogated endothelial cell responses when added together. Thus, the whole blood effect begins with LPS activation of monocytes via cell membrane CD14 and results in endothelial cell activation by the effects of TNF and IL-1. The monokine-mediated endothelial cell activation is referred as to the indirect pathway.

Cells, Cultured↗
PubMed1994

CD14 is a pattern recognition receptor.

Septic shock caused by a diverse group of bacterial pathogens is a serious human disease. Recognition of bacterial envelope constituents is one mechanism used by mammalian cells to initiate responses leading to bacterial killing or, unfortunately, responses that also cause fatal septic shock. Here we show that CD14 plays a key role in initiating cell activation by a group of bacterial envelope components from Gram-negative and Gram-positive microorganisms, as well as mycobacteria. We propose that CD14 is a receptor used by mammalian cells to recognize and signal responses to a diverse array of bacterial constituents. This finding defines the molecular basis for innate microbial immunity; implicit in these findings are new possibilities for therapeutics.

Animals↗
PubMed1994

Lipopolysaccharide (LPS)-binding protein and soluble CD14 function as accessory molecules for LPS-induced changes in endothelial barrier function, in vitro.

Bacterial LPS induces endothelial cell (EC) injury both in vivo and in vitro. We studied the effect of Escherichia coli 0111:B4 LPS on movement of 14C-BSA across bovine pulmonary artery EC monolayers. In the presence of serum, a 6-h LPS exposure augmented (P < 0.001) transendothelial 14C-BSA flux compared with the media control at concentrations > or = 0.5 ng/ml, and LPS (10 ng/ml) exposures of > or = 2-h increased (P < 0.005) the flux. In the absence of serum, LPS concentrations of up to 10 micrograms/ml failed to increase 14C-BSA flux at 6 h. The addition of 10% serum increased EC sensitivity to the LPS stimulus by > 10,000-fold. LPS (10 ng/ml, 6 h) failed to increase 14C-BSA flux at serum concentrations < 0.5%, and maximum LPS-induced increments could be generated in the presence of > or = 2.5%. LPS-binding protein (LBP) and soluble CD14 (sCD14) could each satisfy this serum requirement; either anti-LBP or anti-CD14 antibody each totally blocked (P < 0.00005) the LPS-induced changes in endothelial barrier function. LPS-LBP had a more rapid onset than did LPS-sCD14. The LPS effect in the presence of both LBP and sCD14 exceeded the effect in the presence of either protein alone. These data suggest that LBP and sCD14 each independently functions as an accessory molecule for LPS presentation to the non-CD14-bearing endothelial surface. However, in the presence of serum both molecules are required.

Acute-Phase Proteins↗
PubMed1994

Lack of correlation between tritiated deoxyglucose, thallium-201 and technetium-99m-MIBI cell incorporation under various cell stresses.

UNLABELLED: The use of fluorodeoxyglucose (FDG) and PET, recognized as an accurate tool for the specific diagnosis and staging of cancer, is currently being tested to monitor cancer therapy. Similar investigations have been performed with the nonPET markers 201Tl and 99mTc-methoxyisobutylisonitrile (MIBI), two markers of myocardial perfusion shown to concentrate in malignant cells. We have tested the hypothesis that the cellular incorporation of 201Tl and 99mTc-MIBI reflects that of FDG and correlates with treatment efficacy. METHODS: We measured the incorporation in U937 cells of tritiated deoxyglucose (3H-DG), 201Tl and 99mTc-MIBI in basal conditions after stimulation or inhibition of the glucose metabolic pathway and after exposure to toxic agents selected to mimic the effects of chemotherapy. Thallium-201 or 99mTc-MIBI cell incorporation remained at basal levels after exposure to insulin, whereas 3H-DG cell incorporation was greatly enhanced. Conversely, in the presence of 50 microM of NaF for 3 hr, only 3H-DG cell incorporation was reduced to 57.2% +/- 6.2% from control conditions. Cycloheximide (CYX), metaiodobenzylguanidine (MIBG) and bleomycin (BLM) were added to cell cultures. RESULTS: Neither 201Tl nor 99mTc-MIBI followed the changes in cell incorporation observed with 3H-DG. In addition, only 3H-DG cell incorporation was inversely correlated to the time of cell exposure or to the cell culture concentration of MIBG and BLM. CONCLUSION: In this model, cell incorporation of 201Tl or 99mTc-MIBI differed from cell incorporation of 3H-DG suggesting that it was not directly related to cell glycolysis activity and cell injury. In conclusion, these results do not support the hypothesis that 201Tl or 99mTc-MIBI could replace FDG to monitor cancer treatment.

3-Iodobenzylguanidine↗
PubMed1993

A critical role for monocytes and CD14 in endotoxin-induced endothelial cell activation.

Vascular endothelium activated by endotoxin (lipopolysaccharide [LPS]) and cytokines plays an important role in organ inflammation and blood leukocyte recruitment observed during sepsis. Endothelial cells can be activated by LPS directly, after its interaction with LPS-binding protein and soluble CD14 in plasma. LPS-LPS-binding protein complexes in blood also interact with monocytes and neutrophils bearing glycosyl-phosphatidylinositol (GPI) anchored membrane CD14 (mCD14), promoting the release of cytokines such as tumor necrosis factor and interleukin 1 (IL-1). These molecules, in turn, have the capacity to activate endothelial cells providing an indirect pathway for LPS-dependent endothelial cell activation. In this work, we address the relative importance of the direct and the indirect pathway of in vitro LPS-induced human umbilical vein endothelial cell (HUVEC) activation. Substituting whole blood for plasma resulted in a 1,000-fold enhancement of HUVEC sensitivity to LPS. Both blood- and plasma-dependent enhanced activation of HUVEC were blocked with an anti-CD14 monoclonal antibody. Blood from patients with paroxysmal nocturnal hemoglobinuria, whose cells lack mCD14 and other GPI anchored proteins, was unable to enhance LPS activation of HUVEC above the level observed with plasma alone. IL-10, an inhibitor of monocyte release of cytokines, decreased the blood-dependent enhancement of HUVEC activation by LPS. Blood adapted to small doses of LPS was also less efficient than nonadapted blood in producing this enhancement. Addition of purified mononuclear cells to HUVEC or the transfer of plasma from whole blood incubated with LPS to HUVEC, duplicated the enhancement effect observed when whole blood was incubated with HUVEC. Taken together, these data suggest that the indirect pathway of LPS activation of endothelial cell is mediated by monocytes and mCD14 through the secretion of a soluble mediator(s). The indirect pathway is far more efficient than the direct, plasma-dependent pathway.

Antigens, CD↗
PubMed1993

Lipopolysaccharide activation of human endothelial and epithelial cells is mediated by lipopolysaccharide-binding protein and soluble CD14.

Myeloid cell activation by lipopolysaccharides (LPS) involves two proteins, plasma LPS-binding protein (LBP) and cell-membrane CD14. Cell membrane CD14, anchored by a glycerophosphatidylinositol tail, is the cellular receptor for LPS-LBP complexes. Another form of CD14, without the lipid tail, circulates as a soluble plasma protein. In this work we show that soluble CD14 (sCD14) is required for activation of endothelial and epithelial cells by LPS. We propose that LPS-LBP complexes transfer LPS to sCD14, and the LPS-sCD14 complexes then bind to a cellular receptor. Support for this pathway comes from experiments in which LBP and CD14 in normal human serum are blocked by specific antibodies, experiments in which serum is replaced by purified LBP and sCD14, and experiments in which specific binding of [3H]LPS to epithelial cells is quantitated.

Acute-Phase Proteins↗
PubMed1992

Diagnostic bronchoalveolar lavage in patients with pneumonia produces sepsis-like systemic effects.

Fever following fiberoptic bronchoscopy occurs in 10-25% of the patients and its origin is not well understood. We prospectively examined changes in body temperature (T degrees), mean systemic arterial pressure (MAP) and oxygenation after 2 bronchoalveolar lavages (BAL, bronchoscopic and non-bronchoscopic) for 34 procedures in 25 intubated patients. In patients with pneumonia (11 investigations) we observed a rise in T degrees 3 h after bronchoscopic and non-bronchoscopic BAL, p less than 0.0001, a decrease in MAP, p = 0.008 and arterial oxygenation, p = 0.002. Of patients with pneumonia 73% had a rise in T degrees of more than 1 degrees C compared with only 17% of those without pneumonia (p = 0.005). Patients without pneumonia (23 procedures) had no significant changes in T degrees, MAP and arterial oxygenation following the 2 BAL procedures. Changes in T degrees correlated significantly with those in MAP, and with the level of endotoxin in bronchoscopic BAL fluid. These findings suggest that BAL in patients with pneumonia may cause intravascular translocation of toxins or mediators producing pyrogenic and hypotensive effects.

Adolescent↗
PubMed1992

Rapid diagnosis of gram negative pneumonia by assay of endotoxin in bronchoalveolar lavage fluid.

BACKGROUND: Diagnosis of ventilator associated pneumonia can be made by quantitative cultures of bronchoalveolar lavage fluid or of protected specimen brushings, though cultures require 24-48 hours to provide results. In 80% of cases aerobic Gram negative bacteria are the cause. METHODS: A rapid diagnostic method of assessing the endotoxin content of lavage fluid by Limulus assay is described. Forty samples of lavage fluid were obtained from patients with multiple trauma requiring mechanical ventilation for a prolonged period. Pneumonia was diagnosed on the basis of clinical, radiological, and bacteriological findings, including quantitative cultures of lavage fluid. RESULTS: A relation was observed between the concentration of endotoxin in lavage fluid and the quantity of Gram negative bacteria. The median endotoxin content of lavage fluid in Gram negative bacterial pneumonia was 15 endotoxin units (EU)/ml; the range observed in individual patients was 6 to > 150 EU/ml. In patients with pneumonia due to Gram positive cocci and in non-infected patients the median endotoxin level was 0.17 (range < or = 0.06 to 2) EU/ml. An endotoxin level greater than or equal to 6 EU/ml distinguished patients with Gram negative bacterial pneumonia from colonised patients and from those with pneumonia due to Gram positive cocci. CONCLUSION: The measurement of endotoxin in lavage fluid is a rapid (less than two hours) and accurate diagnostic method. It should allow specific and early treatment of Gram negative bacterial pneumonia.

Bronchoalveolar Lavage Fluid↗
PubMed1992

Participation of lipopolysaccharide-binding protein in lipopolysaccharide-dependent macrophage activation.

Only recently has the mechanism for lipopolysaccharide (LPS) recognition by macrophages been elucidated. In contrast to many ligand receptor interactions, the interaction of LPS with its receptor, CD14, on myeloid cells is greatly enhanced by prior complexation of LPS with LPS-binding protein (LBP), a recently discovered plasma glycoprotein. LBP is found in normal serum or plasma in the 5 to 10 micrograms/ml range. In plasma, it reacts rapidly but transiently with LPS. LPS-LBP complexes then react with CD14 bearing cells. Blocking CD14 with monoclonal antibodies or removal of LBP from plasma blocks the ability of the cells to react with LPS-LBP complexes and also blocks release of cytokines and other mediators from the cells. In the normal lung, bronchoalveolar lavage fluid contains low levels of LBP. However, during acute lung injury, LBP levels may rise by transudation and enhance activation of alveolar macrophages to release injurious mediators. Description of this pathway for LPS recognition by macrophages and other leukocytes offers the possibility of developing new reagents to block LPS recognition and prevent the development of endotoxemia.

Acute-Phase Proteins↗
PubMed1991

[ The intestine-liver-lung axis in septic syndrome].

Abacteremic sepsis is frequent in intensive care units, and is closely associated with the development of adult respiratory distress syndrome (ARDS) and multiple systems organ failure (MSOF). It carries a high mortality. The gut is thought to be the "motor" of such septic states and the first step of a "gut-liver-lung axis". Shock of any type or sepsis can by themselves lead to increased permeability of the intestinal mucosal barrier. This, in turn, may promote bacterial translocation, i.e. the passage of bacteria or bacterial products such as endotoxin from the lumen of the gut into the portal bloodstream. When such products reach the liver, activation of Küpffer cells occurs, resulting in the secretion of pro-inflammatory and hypotensive mediators. The latter are mainly the tumor necrosis factor-alpha and interleukins-1 and -6. These substances trigger many biologic cascades, and may explain the development of abacteremic septic states and MSOF. The mediators cause binding of polymorphonuclear neutrophils to pulmonary endothelial cells, and their degranulation. In addition, they activate local and systemic coagulation mechanisms. This explains the morphological changes observed in early sepsis-induced ARDS, i.e. pulmonary edema, vascular thrombosis and hemorrhages. Studies are currently in progress in an attempt to limit bacterial and endotoxin translocation and the action of the mediators.

Bacterial Physiological Phenomena↗
PubMed1991

Diagnosis of ventilator-associated pneumonia by bacteriologic analysis of bronchoscopic and nonbronchoscopic "blind" bronchoalveolar lavage fluid.

Substantial efforts have been devoted to improving the means for early and accurate diagnosis of ventilator-associated (VA) pneumonia in intensive care unit (ICU) patients because of its high incidence and mortality. A good diagnostic yield has been reported from quantitative cultures of bronchoalveolar lavage (BAL) fluid or a protected specimen brush, both obtained by fiberoptic bronchoscopy. As bronchoscopy requires specific skills and is costly, we evaluated a simpler method to obtain BAL fluid, that is, by a catheter introduced blindly into the bronchial tree. Quantitative cultures from bronchoscopically sampled BAL (B-BAL) and blindly nonbronchoscopically collected BAL (NB-BAL) were assessed for sensitivity, specificity, and predictive value for the diagnosis of VA pneumonia. A total of 40 pairs of samples were examined in 28 patients requiring prolonged mechanical ventilation and presenting a high risk of developing pneumonia. For comparison with bacteriologic data we defined a clinical score for pneumonia ranging from zero to 12 using the following variables: body temperature, leukocyte count, volume and character of tracheal secretions, arterial oxygenation, chest X-ray, Gram stain, and culture of tracheal aspirate. To quantify the bacteria in BAL the bacterial index (BI) was used, defined as the sum of the logarithm of the number of bacteria cultured per milliliter of BAL fluid. A good correlation between clinical score and quantitative bacteriology was observed (r = 0.84 for B-BAL and 0.76 for NB-BAL; p less than 0.0001). Similar to studies in baboons, patients with pulmonary infection could be distinguished by a BI greater than or equal to 5 with a sensitivity of 93% and a specificity of 100% (B-BAL).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[The diagnosis of pneumonia in the ventilated patient].

The diagnosis of ventilator-associated pneumonia is difficult to confirm because the usual clinical criteria lack predictive value. Risk factors evaluated recently serve to assess subgroups of exposed patients. Bronchoscopic bronchoalveolar lavage (BAL) or protected specimen brush, together with quantitative bacteriology, are the present method of choice for diagnosis of nosocomial pneumonia during mechanical ventilation. Nonbronchoscopic "blind" BAL catheters provide new, attractive, accurate and easy sampling techniques. This could become the technique of choice in the future. Efforts are needed to standardize diagnostic criteria, in order to allow comparisons between groups of patients or clinical trials for prevention or treatment of ventilator-associated pneumonia.

Bacteriological Techniques↗
PubMedDate not supplied

Oropharyngeal decontamination decreases incidence of ventilator-associated pneumonia. A randomized, placebo-controlled, double-blind clinical trial.

Secondary pneumonia in patients requiring mechanical ventilation has a high morbidity and mortality. Diagnosis is difficult and treatment failure common; therefore, preventive measures are important. In a double-blind, placebo-controlled trial, we evaluated selective decontamination of the oropharynx with polymyxin B sulfate, neomycin sulfate, and vancomycin hydrochloride (PNV) in 52 patients requiring mechanical ventilation during a 3- to 34-day period (mean, 10 days). Either PNV or placebo was administered six times daily in the oropharynx. During the first 12 days of intubation, tracheobronchial colonization by gram-negative bacteria and Staphylococcus aureus, as well as pneumonia, occurred less frequently in the PNV than in the placebo group (16% vs 78%; P less than .0001). Hospital mortality was not different, but systemic antibiotics were prescribed less often in the PNV group and no resistant microorganism emerged. In these critically ill patients, topical oropharyngeal antibiotic application lowered the rate of ventilator-associated pneumonia by a factor of 5, probably by interrupting the stomach-to-trachea route of infection, and decreased the requirement for intravenous antibiotics.

Adult↗