Biomedical subjects

C Vesin

Publications and source records attributed to C Vesin.

At least 19 recordsLinked to original sources

PubMed1999

Urokinase receptor (uPAR, CD87) is a platelet receptor important for kinetics and TNF-induced endothelial adhesion in mice.

BACKGROUND: Urokinase plasminogen activator receptor (uPAR, CD87) is a widely distributed 55-kD, glycoprotein I-anchored surface receptor. On binding of its ligand uPA, it is known to increase leukocyte adhesion and traffic. Using genetically deficient mice, we explored the role of uPAR in platelet kinetics and TNF-induced platelet consumption. METHODS AND RESULTS: Anti-uPAR antibody stained platelets from normal (+/+) but not from uPAR-/- mice, as seen by fluorescence-activated cell sorter analysis. 51Cr-labeled platelets from uPAR-/- donors survived longer than those from +/+ donors when injected into a +/+ recipient. Intratracheal TNF injection induced thrombocytopenia and a platelet pulmonary localization, pronounced in +/+ but absent in uPAR-/- mice. Aprotinin, a plasmin inhibitor, decreased TNF-induced thrombocytopenia. TNF injection markedly reduced the survival and increased the pulmonary localization of 51Cr-labeled platelets from +/+ but not from uPAR-/- donors, indicating that it is the platelet uPAR that is critical for their response to TNF. As seen by electron microscopy, TNF injection increased the number of platelets and polymorphonuclear neutrophils (PMNs) in the alveolar capillaries of +/+ mice, whereas in uPAR-/- mice, platelet trapping was insignificant and PMN trapping was slightly reduced. Platelets within alveolar capillaries of TNF-injected mice were activated, as judged from their shape, and this was evident in +/+ but not in uPAR-/- mice. CONCLUSIONS: These results demonstrate for the first time the critical role of platelet uPAR for kinetics as well as for activation and endothelium adhesion associated with inflammation.

Animals↗

PubMed1999

Keratinocyte growth factor protects alveolar epithelium and endothelium from oxygen-induced injury in mice.

Keratinocyte growth factor (KGF) has been used successfully to prevent alveolar damage induced by oxygen exposure in rodents. However, this treatment was used intratracheally and before oxygen exposure, which limited its clinical application. In the present study, mice were treated with the recombinant human KGF intravenously before (days -2 and -1) or during (days 0 and +1) oxygen exposure. In both cases, lung damage was attenuated. KGF increased the number of cells incorporating bromodeoxyuridine (BrdU) in the septa and in bronchial epithelium of air-breathing mice but not of oxygen-exposed mice, indicating that the protective effect of KGF is not necessarily associated with proliferation. Oxygen-induced damage of alveolar epithelium and, unexpectedly, of endothelium was prevented by KGF treatment as seen by electron microscopy. We investigated the effect of KGF on different mechanisms known to be involved in oxygen toxicity. The induction of p53, Bax, and Bcl-x mRNAs during hyperoxia was to a large extent prevented by KGF. Surfactant proteins A and B mRNAs were not markedly modified by KGF. The anti-fibrinolytic activity observed in the alveoli during hyperoxia was to a large extent prevented by KGF, most probably by suppressing the expression of plasminogen activator inhibitor-1 (PAI-1) mRNA and protein. As PAI-1 -/- mice are more resistant to hyperoxia, KGF might act, at least in part, by decreasing the expression of this protease inhibitor and by restoring the fibrinolytic activity into the lungs.

Animals↗

PubMed1999

TNF-induced enterocyte apoptosis and detachment in mice: induction of caspases and prevention by a caspase inhibitor, ZVAD-fmk.

Injection of mouse recombinant TNF to mice induced apoptosis and detachment of the enterocytes of the tip of the villi, evident after 30 to 90 minutes, which resulted in a shrinkage of the villi. Injection of TNF increased the expression of caspase 1, 2, 3, and 6 as well as of cathepsin D in the mucosal wall, which was maximal 30 minutes after TNF injection. Caspase 1 and 3 were not induced in TNFR1-deficient mice in which TNF does not induce apoptosis and detachment. The administration of a caspase inhibitor (ZVAD-fmk, 300 microg) decreased enterocyte detachment and apoptosis, as well as villus atrophy, whereas a caspase 3 inhibitor (Z-DEVD-cmk) had no effect. The results indicate that the induction of caspases by TNF is the cause of their detachment in the lumen and of the resulting villus atrophy.

Amino Acid Chloromethyl Ketones↗

PubMed1998

Role of TNFR1 and TNFR2 in TNF-induced platelet consumption in mice.

An injection of TNF in mice induced profound thrombocytopenia, due to an increase of platelet consumption, that was evident after 1 h and lasted for 3 days. This process was evident in mice that were genetically deficient in TNFR2 (p75) but not in mice lacking TNFR1 (p55), indicating that the process is mediated by TNFR1-bearing cells. To explore the site of action of TNF, labeled platelets from TNFR1 -/- or +/+ donors were transferred to TNFR1 -/- or +/+ recipients. TNF induced the consumption of platelets from TNFR1 -/- donors when injected into +/+ recipients, while platelets from +/+ donors were not consumed when present in TNFR1 -/- recipients; this finding indicates that TNF acts on the TNFR1 of host cells but does not act on platelets. The expression of TNFRs is consistent with this interpretation, since TNFRs were not detected on platelets by flow cytometry. In megakaryocytes, the expression of TNFR1 was detected by immunohistochemistry. These results indicate that TNF induces platelet consumption by acting not on platelets directly but on the TNFR1 of other cells, presumably increasing the release of factors with agonist activity for platelets.

Animals↗

PubMed1998

TNF-induced enterocyte apoptosis in mice is mediated by the TNF receptor 1 and does not require p53.

Injection of recombinant mouse TNF into mice is known to induce a shrinkage of the duodenal villi, which becomes evident 30-90 min later and is associated with a detachment of enterocytes in the lumen. These cells can be collected by lavage and are all apoptotic, i.e. hypodiploid as seen by flow cytometric analysis. Thus the count of detached cells was used as an evaluation of the TNF-induced cell loss and apoptosis in the mucosa. TNF injection induced a cell loss of similar magnitude in wild-type (+/+) or in mice lacking the TNF receptor (TNFR)2 (p75, TNFR2-/-), while mice lacking the TNFR1 (p55, TNFR1-/-) were completely resistant to this effect. TNF increased the expression of p53 tumor suppressor gene in the enterocytes from the crypts but not from the villi, as seen by Western blots and histochemistry. TNF increased the expression of p53 in both TNFR2-/- and TNFR1-/- mice. Furthermore, enterocyte cell loss was not attenuated in p53-/- mice. The results indicate that TNF, acting on its receptor 1, induces an apoptotic detachment of the enterocytes from the tip of the villi (i.e. the old enterocytes), while in the enterocytes from the crypts (the young enterocytes) TNF increases, via either TNFR1 or TNFR2, the expression of p53, without inducing apoptosis.

Animals↗

PubMed1998

Role of mast cells and monoamines in the thrombocytopaenia and mortality elicited by tumour necrosis factor in mice.

We explored the thrombocytopaenia elicited by the i.v. injection of mouse recombinant tumour necrosis factor (TNF) in mice. Injection of 10 micrograms of TNF led to a thrombocytopaenia (evident after 0.5 hr) which was caused by decreased platelet survival, as seen by the injection of labelled platelets. TNF-induced thrombocytopaenia was not prevented by heparin, nor by depletion of either fibrinogen or C'. TNF-induced thrombocytopaenia was markedly attenuated in mice treated with reserpine, an agent that depletes monoamines from mast cells and other cells, and in the mast-cell-deficient WWv mice. In vitro, TNF elicited a modest release of monoamine from peritoneal mast cells and from a mast cell line. When mice are injected with 3H-serotonin (3H-5HT) before TNF, TNF injection increased the plasma 3H-5HT content 1 hr later, modifications absent in reserpine pretreated or mast-cell-deficient mice. 3H-5HT content of the small intestine was markedly depleted in TNF-injected mice, suggesting that this organ is the source of the plasma 3H-5HT. Drop in body temperature and mortality induced by TNF were also attenuated in mast-cell-deficient, and in reserpine pretreated mice. These results indicate that TNF can induce a release of monoamines from mast cells, mainly from those of the small intestine, a process that contributes to TNF-induced thrombocytopaenia and mortality.

Adrenergic Uptake Inhibitors↗

PubMed1997

Platelets play an important role in TNF-induced microvascular endothelial cell pathology.

Tumor necrosis factor-alpha (TNF) is known to be an important mediator in the pathogenesis of several inflammatory diseases. Vascular endothelial cells represent a major target of TNF effects. Platelet sequestration has been found in brain microvessels during experimental cerebral malaria and lung in experimental pulmonary fibrosis, implying that it may participate in TNF-dependent microvascular pathology. In this study, we investigated the mechanisms of platelet-endothelial interaction, using co-cultures between platelets and TNF-activated mouse brain microvascular endothelial cells (MVECs). Adhesion and fusion of platelets to MVECs was evidenced by electron microscopy, dye transfer, and flow cytometry. It was induced by TNF and interferon-gamma and depended on LFA-1 expressed on the platelet surface and ICAM-1 expressed on MVECs. The adhesion and fusion also led to the transfer of platelet markers on the MVEC surface, rendering these more adherent for leukocytes, and to an enhanced MVEC sensitivity to TNF-induced injury. These results suggest that platelets can participate in TNF-induced microvascular pathology.

Animals↗

PubMed1996

Activated human platelets express beta2 integrin.

The expression of molecules of the beta2 integrin family (CD11a, CD11b , CD11c, and CD18) was explored on 2 human megakaryocytic cell lines and on platelets from different donors by immunofluorescence and flow cytometry using a large panel of mAb. CD11a, CD11b, CD11c and CD18 were detected on the megakaryocytic cell lines DAMI and HEL. A low and variable expression of CD11a, CD11b and CD18 determinants was also detected on resting platelets; this expression was markedly increased when platelets were activated by thrombin. Expression of CD18 was closely correlated to that of CD11a or CD11b when comparing the fluorescence intensity observed in different experiments. In presence of Ca++, platelets did bind to a RAJI cell line which exhibits a high expression level of CD54. This binding was increased when platelets were activated by thrombin and was decreased by an anti CD11a, CD18 and anti CD54 mAb. This study indicates that human platelets express molecules of the beta2 integrin family, when activated, which allows them to bind to CD54 bearing cells.

Animals↗

PubMed1996

Hyperoxia induces platelet activation and lung sequestration: an event dependent on tumor necrosis factor-alpha and CD11a.

Mice were exposed to pure oxygen for various times to explore the pulmonary platelet trapping associated with alveolar damage, its mechanism, and its role in the lesions. Platelet sequestration, evaluated by electron microscopy and by injection of radiolabeled platelets, was detectable after 72 h and reached a maximum after 96 h of exposure (i.e., shortly before death). Circulating platelets (analyzed by Facscan) showed some increase in the expression of CD11a and CD62, but little change in CD31 and CD61. Both platelet activation and lung sequestration were dependent on TNF-alpha, since antibody against TNF-alpha reduced the expression of CD11a on circulating platelets and their sequestration in the lung. Lung platelet sequestration was also decreased by anti-CD11a MoAb. Northern blot analysis of lung mRNA isolated at 96 h of oxygen exposure revealed a 7-fold increase in CD54 (intercellular adhesion molecule-1 [ICAM-1]) and a 2.5-fold increase in TNF-alpha mRNAs respectively. These results demonstrate that the platelet pulmonary trapping induced by hyperoxia is dependent upon TNF-alpha and the CD11a-CD54 adhesion molecules. However, platelet trapping does not appear to play an important pathogenic role in acute oxygen injury, since treatments that decrease trapping (anti-TNF-alpha, anti-CD11a, or antibody-induced thrombocytopenia) did not markedly attenuate the alveolar damage.

Animals↗

PubMed1995

Administration of anti-TNF-alpha or anti-CD11a antibodies to normal adult mice decreases lung and bone collagen content: evidence for an effect on platelet consumption.

Administration of anti-tumor necrosis factor-alpha (anti-TNF-alpha) or anti-CD11a (LFA-1) antibodies to normal adult mice for about 10 days markedly decreased the hydroxyproline content in lung and femur. Similar observation was made using the recombinant soluble TNF receptor (rsTNFR) as tumor necrosis factor-alpha (TNF-alpha) antagonist. This decrease in collagen content was most likely due to a decrease of collagen synthesis, as evidenced by a decrease of the 3H-proline incorporation in lung and bone and by a decrease of collagen alpha 1 (I) mRNA levels in the lung RNA. The localization of labeled platelets in the lung of normal mice was decreased by anti-TNF-alpha but not by anti-CD11a antibodies. Thrombocytopenia increases the localization of labeled platelets in the lung, and, in this condition, both anti-TNF-alpha and anti-CD11a antibodies decreased pulmonary trapping. TNF-alpha mRNA was detected in the lung of normal adult mice, suggesting that this cytokine is released in the absence of inflammation. These results indicate that in vivo, endogenous TNF-alpha stimulates collagen synthesis, most likely by its influence on platelet trapping, which appears to involve the platelet CD11a since it is decreased by anti-CD11a antibody.

Animals↗

PubMed1995

Expression of a tumor necrosis factor-alpha transgene in murine lung causes lymphocytic and fibrosing alveolitis. A mouse model of progressive pulmonary fibrosis.

The murine TNF-alpha gene was expressed under the control of the human surfactant protein SP-C promoter in transgenic mice. A number of the SP-C TNF-alpha mice died at birth or after a few weeks with very severe lung lesions. Surviving mice transmitted a pulmonary disease to their offspring, the severity and evolution of which was related to the level of TNF-alpha mRNA in the lung; TNF-alpha RNA was detected in alveolar epithelium, presumably in type II epithelial cells. In a longitudinal study of two independent mouse lines, pulmonary pathology, at 1-2 mo of age, consisted of a leukocytic alveolitis with a predominance of T lymphocytes. Leukocyte infiltration was associated with endothelial changes and increased levels of mRNA for the endothelial adhesion molecule VCAM-1. In the following months, alveolar spaces enlarged in association with thickening of the alveolar walls due to an accumulation of desmin-containing fibroblasts, collagen fibers, and lymphocytes. Alveolar surfaces were lined by regenerating type II epithelial cells, and alveolar spaces contained desquamating epithelial cells in places. Platelet trapping in the damaged alveolar capillaries was observed. Pulmonary pathology in the SP-C TNF-alpha mice bears a striking resemblance to human idiopathic pulmonary fibrosis, in which increased expression of TNF-alpha in type II epithelial cells has also been noted. These mice provide a valuable animal model for understanding the pathogenesis of pulmonary fibrosis and exploring possible therapeutic approaches.

Animals↗

PubMed1994

Role of polymorphonuclear neutrophil leukocytes and their integrin CD11a (LFA-1) in the pathogenesis of severe murine malaria.

Infection of CBA mice with Plasmodium berghei ANKA results in severe malaria, which is characterized by mortality 6 to 10 days after infection and is associated with alterations of the brain microcirculation. These alterations consist of (i) intravascular sequestration of monocytes, (ii) an increase in vascular permeability as documented by Evans blue diffusion, and (iii) microhemorrhages. This syndrome may be due to an increase of production of tumor necrosis factor alpha which upregulates the endothelial expression of ICAM-1 and thus leads to adhesion of CD11a/CD18 (LFA-1)-bearing cells. During severe malaria, we found an important sequestration of the CD11a-bearing polymorphonuclear neutrophil leukocytes (PMN) in the lung but not in the brain. Treatment with a monoclonal antibody (MAb) against PMN, which induces profound neutropenia, prevented mortality and Evans blue diffusion in the brain and the lung, while it unexpectedly increased the occurrence of microhemorrhages. The anti-PMN MAb abolished PMN sequestration in the lung and also partially decreased monocyte sequestration in the brain and the lung. Treatment with an anti-CD11a MAb also prevented mortality, Evans blue diffusion, and PMN and monocyte sequestration. This study shows that PMN contribute to the mortality and the microvascular lesions resulting from severe malaria. This may be due to their CD11a-dependent sequestration in the lung and also to their indirect influence on vascular permeability and the sequestration of monocytes.

Animals↗

PubMed1994

Treatment by human recombinant soluble TNF receptor of pulmonary fibrosis induced by bleomycin or silica in mice.

Intratracheal instillation of bleomycin (0.08 U) or silica (2 mg) to mice leads, after 15 days, to a patchy pulmonary fibrosis associated with a significant increase of the lung hydroxyproline. Since tumour necrosis factor (TNF) seems to be an important mediator in pulmonary fibrosis, we wondered whether this fibrosis might be prevented by a new TNF-alpha antagonist. Infusion of a 55 kD human recombinant soluble TNF receptor rsTNFR-beta, at a rate of 20 micrograms.day-1, prevented the bleomycin/silica induced increase of lung hydroxyproline content, as measured 15 days after instillation. Infusion of rsTNFR-beta was also effective in the treatment of an established fibrosis, i.e. administered 25 or more days after instillation of bleomycin or silica, since it reduced lung collagen content. Recombinant soluble TNFR-beta had no significant influence on the number of cells, mostly macrophages, recovered by bronchoalveolar lavage. The examination of histological sections indicated that the rsTNFR-beta reduced the proportion of areas of damaged lung and, in silicosis, the formation of nodules with a rich collagen content. This study suggests that rsTNFR-beta might be useful in the therapy of pulmonary fibrosis.

Animals↗

PubMed1994

Pulmonary platelet trapping induced by bleomycin: correlation with fibrosis and involvement of the beta 2 integrins.

Platelet trapping was explored during the course of bleomycin induced pulmonary fibrosis by the injection of indium-111 labelled platelets and by light and electron microscopy (EM) of the alveolar capillaries. An i.v. injection of bleomycin markedly increased the localization of labelled platelets in the lung (but not in other organs) for about 3 weeks. On day 7 after bleomycin injection, a significant increase in the number of platelets in contact with the alveolar endothelium was seen with EM. Platelet trapping was strongly correlated (P < 0.005) with collagen deposition when examined in mouse strains genetically susceptible (CBA, C57BL/10, BL10 A.2R), or resistant (Balb/c, BL10.D2, BL10.A), to bleomycin induced fibrosis. In addition, several treatments known to decrease bleomycin induced collagen deposition and synthesis, namely administration of antibodies against CD11a, CD11b, TNF-alpha and IL-1ra, also decreased platelet trapping. As evaluated by EM, anti CD11a mAb significantly decreased the number of platelets in contact with the alveolar endothelium. This study indicates that bleomycin induced pulmonary fibrosis is strongly correlated with platelet trapping and that platelets probably interact, via their CD11a, with the CD54 born by the alveolar endothelium.

Animals↗

PubMed1993

Respective role of polymorphonuclear leukocytes and their integrins (CD-11/18) in the local or systemic toxicity of lipopolysaccharide.

The role of neutrophils (PMNs) and leukocyte integrins was investigated in two models of lipopolysaccharide (LPS)-induced toxicity: the systemic lethality assay in D-galactosamine-sensitized mice and the local reaction elicited by intradermal injection of LPS and tumor necrosis factor (TNF) at 24-h intervals. In the local reaction, depletion of PMNs with an anti-PMN monoclonal antibody (mAb) and mAbs against CD-11a (or LFA1) and CD-11b (or CR3) completely prevented the hemorrhagic necrosis. Evaluation of histological sections and myeloperoxidase levels suggested different mechanism of protection because PMNs were abundant in anti-CD-11- and absent in anti-PMN-treated mice. In the systemic assay, depletion of PMNs ensured 100% survival, whereas after administration of anti-CD-11a or b mAb, the percentages of survivors were 6 and 59%, respectively. One hour after LPS injection, the serum TNF-alpha level was higher in PMN-depleted mice than in controls. These studies provide evidence that neutrophils are essential for the expression of local or systemic LPS-induced injury, whereas the requirement for their leukocytic integrins is obvious only in the local reaction.

Animals↗

PubMed1993

Interleukin 1 receptor antagonist (IL-1ra) prevents or cures pulmonary fibrosis elicited in mice by bleomycin or silica.

We explored the role of interleukin 1 (IL-1) in two models of pulmonary fibrosis (PF), elicited in mice by the intra-tracheal instillation of bleomycin or silica. In both models, administration of IL-1 receptor antagonist (IL-1ra) by an osmotic minipump implanted i.p., at a rate of 0.5 microgram/h, completely prevented the collagen deposition, as evaluated by the lung hydroxyproline content on day 15 after instillation. IL-1ra had little or no influence on the number of cells recovered from the broncho-alveolar lavage. Study of histological sections suggests that IL-1ra globally decreased the proportion of damaged lung and particularly in silica the formation of nodules with a rich content in collagen fibrils. IL-1ra was also effective in reducing the lung hydroxyproline content when given on day 25 after instillation of bleomycin or silica, indicating that it may reverse established PF. This study indicates that IL-1ra might be useful for the treatment of incipient or established pulmonary fibrosis.

Animals↗

PubMed1993

Protective effect of natural TNF-binding protein on human TNF-induced toxicity in mice.

The in vivo protective effect of urinary TNF-binding protein (uTBP) on acute TNF-induced lesions and lethality was assessed in BALB/c mice. Two animal models, the local Shwartzman reaction and galactosamine (GaLN) induced TNF sensitization, were used. In the former, local cutaneous haemorrhagic necrosis induced by 10 micrograms of recombinant human TNF alpha (r-hTNF) was prevented with iv doses of uTPB as low as 1 microgram when administered concomitantly or 10 micrograms when injected intravenously 60 min before or 30 min after the lesion eliciting-dose of r-hTNF. In the latter model, injection of 1 microgram or r-hTNF caused the death of all mice within 36 h. Either 100 or 250 micrograms of uTBP given intravenously simultaneously with r-hTNF/GaLN totally prevented this mortality. In contrast to anti-human TNF monoclonal antibodies, these very same doses of uTBP significantly protected mice even when injected after the lethal r-hTNF dose. These data confirm in relevant in vivo pathological models the TNF inhibiting capacity of the natural soluble TNF receptor I.

Animals↗

PubMed1993

An effector role for platelets in systemic and local lipopolysaccharide-induced toxicity in mice, mediated by a CD11a- and CD54-dependent interaction with endothelium.

The role of platelets was investigated in two models of lipopolysaccharide (LPS)-induced toxicity in mice: the systemic reaction, provoked by intravenous LPS injection in D-galactosamine-sensitized recipients, which results in host death, and the local reaction, elicited in the skin by sequential injections of LPS and tumor necrosis factor alpha at 24-h intervals, which results in hemorrhagic necrosis. In both models, the depletion of platelets with a rabbit polyclonal or a mouse monoclonal antiplatelet immunoglobulin G afforded significant protection. In the local reaction, studies of the distribution of 111In-labelled platelets as well as optical and electron microscopy showed that platelets are localized in the dermal venules before hemorrhage occurs. Anti-CD11a (LFA-1) and anti-CD54 (ICAM-1) monoclonal antibodies prevented both platelet localization and hemorrhagic necrosis, and these determinants were detected on mouse platelets by immunofluorescence. The antiplatelet monoclonal antibody did not reduce the localization of polymorphonuclear leukocytes in the dermal venules, as shown by histological sections. Thus, in the local reaction, the stimulation with LPS and tumor necrosis factor alpha leads to a binding of platelets to the endothelium of venules by their beta 2 integrins, which seems necessary for the development of the hemorrhagic necrosis.

Animals↗