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Biomedical subjects

G J Francot

Publications and source records attributed to G J Francot.

9 recordsLinked to original sources
PubMed1997

Bactericidal/permeability-increasing protein release in whole blood ex vivo: strong induction by lipopolysaccharide and tumor necrosis factor-alpha.

In this study, the release of bactericidal/permeability-increasing protein (BPI), which is stored in polymorphonuclear leukocytes (PMNL), was analyzed in a whole blood ex vivo system. Of the microbial products tested, lipopolysaccharide (LPS) most potently induced BPI release; FMLP, serum-treated zymosan (STZ), and lipoteichoic acid (LTA) also induced BPI release. In addition, the inflammatory mediator tumor necrosis factor (TNF)-alpha potently activated PMNL in whole blood, via TNF receptor p55, to release BPI, whereas interleukin (IL)-1, IL-8, platelet activating factor, and C5a were poor inducers of BPI release. STZ and phorbol myristate acetate, but not LPS, FMLP, or LTA, stimulated isolated PMNL to release BPI. BPI was released in comparable magnitude with the azurophilic granule protein elastase. Furthermore, both proteins were released with similar kinetics, which started within 30 min after onset of stimulation and lasted 1-4 h.

Antigens, CD↗
PubMed1996

Bactericidal/permeability-increasing protein, a lipopolysaccharide-specific protein on the surface of human peripheral blood monocytes.

Bactericidal/permeability-increasing protein (BPI), a cationic protein present in the azurophilic granule and on the surface of polymorphonuclear leukocytes, specifically interacts with lipopolysaccharide (LPS). This study demonstrates for the first time, using flow cytometry with specific anti-BPI monoclonal antibody (MAb), that human peripheral blood monocytes express BPI on their cell surface. The monocyte cell surface BPI was shown to bind to LPS, because binding of anti-BPI MAb 4E3 (which is known not to react with BPI to which LPS is bound) to cell surface BPI was strongly reduced after preincubation of cells with LPS. However, cell surface BPI did not quantitatively contribute to the interaction of LPS with the monocyte cell membrane, since preincubation of cells with 4E3 did not block binding of LPS-fluorescein isothiocyanate to monocytes. The origin of the monocyte cell surface BPI remains to be further elucidated.

Anti-Bacterial Agents↗
PubMed1995

Presence of bactericidal/permeability-increasing protein in disease: detection by ELISA.

A sandwich ELISA was developed specific for human bactericidal/permeability-increasing protein (BPI), using Mg++ ions to abrogate disturbance by lipopolysaccharide of BPI measurement and to prevent aspecific adherence of BPI to solid phase. In fresh EDTA or heparinized plasma of healthy volunteers BPI was not detectable, whereas in serum BPI was present, indicating that coagulation activates polymorphonuclear leukocytes to release BPI. Furthermore, BPI was present in plasma of critically ill intensive care unit (ICU) patients, in bronchoalveolar lavage fluid of patients suspected of having pneumonia, in wound fluid, and in pleural fluid. In sub-groups of samples with culture-proven bacteria, mean BPI levels were increased compared with subgroups without bacteria, although the differences were only significant in EDTA plasma of ICU patients. These findings indicate the presence of BPI during pathologic conditions. The physiologic role of the released BPI has to be further elucidated.

Animals↗
PubMed1994

Characterization of two monoclonal antibodies directed against bactericidal/permeability-increasing protein.

In this study the production and characterization of two monoclonal antibodies (MAbs), 4E3 and 5D7, against the bactericidal/permeability-increasing protein (BPI) were described. Using ELISAs, both 4E3 and 5D7 were shown to detect recombinant (r) BPI. Furthermore, natural BPI present in polymorphonuclear leukocytes (PMNL) was detected by both 4E3 and 5D7. The use of both MAbs in flow cytometry revealed that PMNL expressed low levels of cell-surface BPI. Lipopolysaccharide (LPS) was shown to block the interaction between anti-BPI MAb and rBPI. In addition, the MAbs blocked biologic activity of rBPI. The inhibition by BPI of LPS activation of the limulus amebocyte lysate assay and of LPS-induced tumor necrosis factor-alpha release by monocytes was prevented by 4E3 and 5D7. Both MAbs are specifically directed against BPI and can inhibit BPI bioactivity.

Animals↗
PubMed1994

Effect of hemodialysis on peripheral blood monocyte tumor necrosis factor-alpha, interleukin-6, and interleukin-8 secretion in vitro.

The influence of blood-membrane interaction on human peripheral blood monocyte tumor necrosis factor-alpha (TNF), interleukin-6 (IL-6), and interleukin-8 (IL-8) secretion was measured during hemodialysis of end-stage renal disease patients by in vitro stimulation of whole blood with lipopolysaccharide. Monocyte TNF and IL-6 secretion in vitro was reduced 30 min after start of dialysis session. In contrast, cellular IL-8 secretion did not change during hemodialysis. Comparison of the results of three different membranes indicates that the bioincompatibility of the dialysis membrane was reflected in both leukocytopenia and reduction of cellular TNF secretion. During treatment of normal whole blood in an ex vivo dialysis closed-loop circuit, the ability of monocytes to release TNF, IL-6, and IL-8 in vitro remained constant. This indicates that the reduced IL-6 and TNF secretion during standard hemodialysis was not due to a direct effect of contact between dialysis membranes and monocytes, but rather was a result of redistribution within the patients' leukocyte pool.

Adult↗
PubMed1993

Antagonistic effects of lipopolysaccharide binding protein and bactericidal/permeability-increasing protein on lipopolysaccharide-induced cytokine release by mononuclear phagocytes. Competition for binding to lipopolysaccharide.

Serum proteins play an important role in LPS-induced cell activation. The LPS binding protein (LBP) enhances cellular responses to LPS, whereas the polymorphonuclear leukocyte product bactericidal/permeability-increasing protein (BPI) inhibits LPS-induced cell activation. In this study the influences of LBP and BPI, two proteins with opposite effects, but with considerable sequence homology, on LPS-induced mononuclear phagocytic cell cytokine release was studied. LBP was shown to enhance LPS-induced TNF-alpha, IL-6, and IL-8 release by mononuclear phagocytic cells, whereas BPI inhibited the release of these cytokines. Furthermore, the effects of LBP and BPI on LPS-induced cytokine release by mononuclear phagocytic cells were shown to be counteractive. BPI interfered with the enhancing effect of LBP on the LPS-induced cytokine release. At high LBP to BPI ratios, BPI could no longer inhibit LBP-induced enhancement. In accordance, increasing concentrations of BPI abrogated the LBP effect. Next, it was shown that LBP and BPI compete for binding to LPS by using an assay system that detects binding of free BPI to an anti-BPI mAb. LPS prevented binding of BPI to anti-BPI mAb, whereas preincubation of LPS with LBP prevented the LPS-induced inhibition. Also, it was observed that both BPI and LBP inhibited LPS activity in the chromogenic LAL assay. We conclude from this study that LBP and BPI have counteractive effects on LPS-induced mononuclear phagocytic cell cytokine release by competing for binding to LPS.

Acute-Phase Proteins↗
PubMed1993

The effect of replacement of dietary fat by palm oil on in vitro cytokine release.

In the present study the effect of replacement of dietary fat by palm oil in the normal Western diet on the in vitro release of the inflammatory cytokines tumour necrosis factor (TNF), interleukin (IL)-6 and IL-8 was examined. A maximal replacement of 700 g/kg dietary fat was achieved for thirty-eight male volunteers who consumed either a palm-oil diet or a control diet in a double-blind, cross-over study with 6-week experimental periods, and 3-week run-in and wash-out periods. At the end of both experimental periods, whole blood was stimulated in vitro with 0.02 (sub-optimal), or 10 ng lipopolysaccharide (LPS)/ml (maximal), whereafter TNF, IL-6, and IL-8 concentrations in the culture supernatant fraction were measured using specific enzyme-linked immunosorbent assays (ELISA). Mean cytokine production with sub-optimal, or maximal LPS stimulation of peripheral whole blood was similar for both the palm oil, and the control group. The relative TNF response, however, was reduced by replacement of dietary fat with palm oil. Separate analysis of the data from the first and second experimental periods strongly suggested that the residual effect of the palm-oil diet on the relative TNF response was longer than 9 weeks. Cytokine homeostasis determines the course of the inflammatory response and the progression of atherosclerosis. The effect of palm-oil consumption on the proneness of the peripheral blood cells to produce TNF may, therefore, alter the prevalence of these common diseases.

Adult↗