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C Bruyns

Publications and source records attributed to C Bruyns.

At least 19 recordsLinked to original sources
PubMed2001

The P2Y11 receptor mediates the ATP-induced maturation of human monocyte-derived dendritic cells.

Recently, it has been shown that ATP and TNF-alpha synergize in the activation and maturation of human dendritic cells (DC); the effect of ATP was reproduced by hydrolysis-resistant derivatives of ATP and was blocked by suramin, suggesting the involvement of a P2 receptor, but the particular subtype involved was not identified. In this report we confirm that ATP and various derivatives synergize with TNF-alpha and LPS to induce the maturation of human monocyte-derived DC, as revealed by up-regulation of the CD83 marker and the secretion of IL-12. The rank order of potency of various analogs (AR-C67085 > adenosine 5'-O-(3-thiotriphosphate) = 2'- and 3'-O-(4-benzoyl-benzoyl) ATP > ATP > 2-methylthio-ATP) was close to that of the recombinant human P2Y11 receptor. Furthermore, these compounds activated cAMP production in DC, in a xanthine-insensitive way, consistent with the involvement of the P2Y11 receptor, which among P2Y subtypes has the unique feature of being dually coupled to phospholipase C and adenylyl cyclase activation. The involvement of the P2Y11/cAMP/protein kinase A signaling pathway in the nucleotide-induced maturation of DC is supported by the inhibitory effect of H89, a protein kinase A inhibitor. Taken together, our results demonstrate that ATP activates DC through stimulation of the P2Y11 receptor and subsequent increase in intracellular cAMP.

Adenosine Triphosphate↗
PubMed2001

A virtual environment for simulated rat dissection.

Animal dissection for the scientific examination of organ subsystems is a delicate procedure. Performing this procedure under the complex environment of microgravity presents additional challenges because of the limited training opportunities available that can recreate the altered gravity environment. Traditional crew training often occurs several months in advance of experimentation, provides limited realism, and involves complicated logistics. We have developed an interactive virtual environment that can simulate several common tasks performed during animal dissection. In this paper, we describe the imaging modality used to reconstruct the rat in virtual space, provide an overview of the simulation environment and briefly discuss some of the techniques used to manipulate the virtual rat.

Animals↗
PubMed2001

Transient expansion of peptide-specific lymphocytes producing IFN-gamma after vaccination with dendritic cells pulsed with MAGE peptides in patients with mage-A1/A3-positive tumors.

Assessment of T-cell activation is pivotal for evaluation of cancer immunotherapy. We initiated a clinical trial in patients with MAGE-A1 and/or -A3 tumors using autologous DC pulsed with MAGE peptides aimed at analyzing T-cell-derived, IFN-gamma secretion by cytokine flow cytometry and ELISPOT. We also tested whether further KLH addition could influence this response favorably. Monocyte-derived DC were generated from leukapheresis products. They were pulsed with the relevant MAGE peptide(s) alone in group A (n=10 pts) and additionally with KLH in group B (n=16 pts). A specific but transient increase in the number of peripheral blood T lymphocytes secreting IFN-gamma in response to the vaccine peptide(s) was observed in 6/8 patients of group A and in 6/16 patients of group B. We conclude that anti-tumor vaccination using DC pulsed with MAGE peptides induces a potent but transient anti-MAGE, IFN-gamma secretion that is not influenced by the additional delivery of a nonspecific, T-cell help.

Adult↗
PubMed2000

Role and expression of CD40 on human retinal pigment epithelial cells.

PURPOSE: To examine the CD40 costimulatory molecule expression on normal resting or activated adult human retinal pigment epithelium (hRPE) cells and to evaluate its role as an activation molecule considering the potential antigen presentation functions of hRPE cells. METHODS: Expression of HLA-DR and costimulatory (CD40, B7.1, B7.2, CD54, and CD58) molecules on hRPE cells was analyzed by flow cytometry. CD40 triggering was performed using soluble CD40L or cocultures with CD40L transfected fibroblasts. Interleukin (IL)-6, -8, -10, and -12 secretions were measured by enzyme-linked immunosorbent assay. Antigen presentation function of hRPE cells was assessed by coculturing hRPE cells with allogeneic T cells. T-cell proliferation was measured by [(3)H]-thymidine incorporation, and T-cell apoptosis by measurement of caspase-3 activity. RESULTS: Interferon (IFN)gamma-activated hRPE cells expressed CD40, but not B7.1 or B7.2. Although interferongamma enhanced IL-6 and IL-8 production, CD40 triggering of IFNgamma-activated hRPE cells did not induce IL-12 secretion. hRPE cells did not stimulate allogeneic resting T cells and downregulated phytohemagglutinin-activated allogeneic T cells via a cell-to-cell contact-dependent mechanism. Some induction of apoptosis was detected. CONCLUSIONS: CD40 is expressed on IFNgamma-activated hRPE cells. Its ligation leads to an increased production of IL-6 and IL-8 but fails to induce B7.1 or B7. 2 expression, or to induce IL-12 secretion. Accordingly, hRPE cells do not activate allogenic T cells but inhibit T-cell proliferation, partly through induction of apoptosis. These results suggest that hRPE cells could be implicated more in a deviant antigen presentation. If the exact molecular mechanisms are unclear, it is likely that CD40-CD40L interaction could play a role in this process.

Animals↗
PubMed1996

Methylprednisolone differentially regulates IL-10 and tumour necrosis factor (TNF) production during murine endotoxaemia.

IL-10 is an endogenous antiinflammatory cytokine that inhibits TNF biosynthesis and protects mice from lipopolysaccharide (LPS)-induced lethality. As synthetic glucocorticoids are widely used as antiinflammatory agents, we analysed the effects of methylprednisolone administration on IL-10 biosynthesis during murine endotoxaemia. We found that low doses of methylprednisolone (2-10 mg/kg) markedly inhibited TNF production but did not affect serum levels of IL-10, while a high methylprednisolone dose (50 mg/kg) increased LPS-induced IL-10 levels. In parallel, we observed that LPS-induced IL-10 production is TNF-independent in this experimental setting. Experiments conducted in vitro indicated that methylprednisolone (from 0.01 to 100 micrograms/ml) also increased the biosynthesis of IL-10 by LPS-activated mouse peritoneal macrophages. We conclude that methylprednisolone differentially regulates IL-10 and TNF production induced by LPS both in vivo and in vitro at the macrophage level.

Adjuvants, Immunologic↗
PubMed1996

Loss of tumorigenicity and increased immunogenicity induced by interleukin-10 gene transfer in B16 melanoma cells.

Because interleukin-10 (IL-10) has potent immunosuppressive and anti-inflammatory properties and is produced by some cancers, we hypothesized that its production might play a role in carcinogenesis by inhibiting adequate antitumoral immune responses. To test this hypothesis, retroviral vectors containing the IL-10 cDNA were generated and used to infect B16F1 melanoma cells that were injected subcutaneously in syngeneic mice. Surprisingly, IL-10 gene transfer resulted in a loss of tumorigenicity that was proportional to the amount of IL-10 secreted. Histological analysis showed massive area of necrosis of these tumor cells, with infiltration of polymorphic inflammatory cells. Parental cells simultaneously implanted had decreased tumorigenicity only when mixed with IL10-producing cells, but not when injected contralaterally, suggesting that their eradication is mediated mostly by a local phenomenon. Host T lymphocytes and natural killer (NK) cells were involved in this eradication because IL-10-producing cells grew in nude mice and in CD8+ or NK-depleted mice. Finally, mice injected with IL-10-secreting cells developed an antitumoral systemic immune response able to protect them against a subsequent challenge with parental cells. These results demonstrate that, in some settings, IL10 may have in vivo immunostimulating and proinflammatory properties that need to be considered in its therapeutic development.

3T3 Cells↗
PubMed1995

Critical role of interleukin 4 in the induction of neonatal transplantation tolerance.

Neonatal injection of semiallogeneic cells is known to promote differentiation of donor-specific CD4+ T cells into TH2-like cells in the peripheral lymphoid organs. We reasoned that the propensity of neonatal T cells to synthesize high levels of IL-4 might be involved in this polarization of the alloreactive response and thereby in the development of neonatal transplantation tolerance. First, analysis of cytokine gene expression in lymph nodes after neonatal injection of 10(7) (A/J x BALB/c)F1 cells in BALB/c mice indicated that IL-4 but not IL-2 is rapidly produced by CD4+ cells after allogeneic challenge in vivo. To determine whether the early production of IL-4 was involved in the establishment of allotolerance, BALB/c mice neonatally injected with (A/J x BALB/c)F1 spleen cells received on days 1 and 3 after birth 1 mg of anti-IL-4 mAb (11B11) or the same amount of control mAb. When grafted with A/J skin at 4 weeks, 88% of mice treated with control mAb retained their graft for more than 50 days, whereas rejection occurred within 30 days in 93% of mice treated with anti-IL-4 mAb. Analysis of T cell functions after in vitro restimulation with A/J spleen cells indicated that early IL-4 neutralization did not prevent donor-specific CTL unresponsiveness but allowed the emergence of alloreactive T cells secreting increased levels of IL-2 and IFN-gamma. We conclude that early production of IL-4 is critical for the establishment of neonatal transplantation tolerance in this strain combination, which has disparities across the entire H-2 region.

Animals↗
PubMed1994

IFN-gamma prevents Th2 cell-mediated pathology after neonatal injection of semiallogenic spleen cells in mice.

BALB/c mice injected at birth with 10(8) (A/J X BALB/c)F1 hybrid spleen cells develop an autoimmune host-vs-graft (HVG) disease as a result of activation of donor B cells by host CD4+ cells. The antidonor CD4+ cells seem to be Th2-like cells, inasmuch as they are profoundly deficient in IL-2 and IFN-gamma production, but secrete high levels of IL-4 and IL-10. As IFN-gamma is known to inhibit the development of TH2 cells, we attempted to modulate HVG disease by injecting rIFN-gamma. First, we found that 10 micrograms of rIFN-gamma given on days 1 and 3 after birth reduced the serum hyper-IgE of HVG mice by 90% and the serum hyper-IgG1, by 70%. In addition, rIFN-gamma administration significantly decreased the anti-DNA IgG1 titers and prevented the occurrence of anti-glomerular basement membrane and anti-laminin IgG1 Abs as well as the formation of immune deposits in renal glomeruli. These effects were not caused by the abrogation of chimerism, as indicated by the persistence of donor-type B cells in lymph nodes and of Igs bearing donor allotype in serum. MLC experiments indicated that the major effect of early rIFN-gamma administration was to restore the production of IL-2 and IFN-gamma by donor-specific T cells while these cells still secreted significant amounts of IL-4 and IL-10. Unresponsiveness of antidonor cytolytic T cells was not influenced by rIFN-gamma. We conclude that rIFN-gamma prevents the TH2-type response induced by the neonatal injection of semiallogeneic spleen cells and the associated pathology.

Animals↗
PubMed1994

Interleukin-10 controls interferon-gamma and tumor necrosis factor production during experimental endotoxemia.

Interleukin-10 (IL-10) is a potent inhibitor of lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF) production and has been shown to protect mice from endotoxin shock. As IFN-gamma is another important mediator of LPS toxicity, we studied the effects of IL-10 on LPS-induced IFN-gamma synthesis in vitro and in vivo. First, we found that the addition of recombinant human IL-10 (rhIL-10) (10 U/ml) to human whole blood markedly suppressed LPS-induced IFN-gamma release while neutralization of endogenously synthesized IL-10 resulted in increased IFN-gamma levels. The ability of rIL-10 to inhibit LPS-induced IFN-gamma synthesis was also observed in vivo in mice. Indeed, administration of 1000 U recombinant mouse IL-10 (rmIL-10) 30 min before and 3 h after challenge of BALB/c mice with 100 micrograms LPS resulted in a threefold decrease in peak IFN-gamma serum levels. We then examined the production and the role of IL-10 during murine endotoxemia. We found that LPS injection causes the rapid release of IL-10, peak IL-10 serum levels being observed 90 min after LPS challenge. Neutralization of endogenously produced IL-10 by administration of 2 mg JES5-2A5 anti-IL-10 monoclonal antibody (mAb) 2 h before LPS challenge resulted in a marked increase in both TNF and IFN-gamma serum levels while irrelevant isotype-matched mAb had no effect. The enhanced production of inflammatory cytokines in anti-IL-10 mAb-treated mice was associated with a 60% lethality after injection of 500 micrograms LPS, while all mice pretreated with control mAb survived. We conclude that the rapid release of IL-10 during endotoxemia is a natural antiinflammatory response controlling cytokine production and LPS toxicity.

Animals↗
PubMed1994

Cytokine gene transfer for the treatment of cancer.

Major progress has been made in the understanding not only of the molecular mechanisms involved in the pathogenesis of cancer, but also of the complex relations between cancer and the immune system. Among the more promising approaches of gene therapy for cancer is the manipulation of the immune system, with the development of an immune antitumoral systemic response. Transfer of some cytokine gene in tumor cells has especially been shown to induce an immune response protecting the animal against subsequent injection of parental tumor cells, and can even, in some cases, treat efficiently animals carrying a preexisting parental tumors. These new experimental data form the basis for the recent elaboration of a rapidly increasing number of clinical protocols using cytokine gene transfer for the treatment of human cancer.

Animals↗
PubMed1993

Interleukin 10 reduces the release of tumor necrosis factor and prevents lethality in experimental endotoxemia.

Because of its ability to efficiently inhibit in vitro cytokine production by activated macrophages, we hypothesized that interleukin (IL) 10 might be of particular interest in preventing endotoxin-induced toxicity. We therefore examined the effects of IL-10 administration before lipopolysaccharide (LPS) challenge in mice. A marked reduction in the amounts of LPS-induced tumor necrosis factor (TNF) release in the circulation was observed after IL-10 pretreatment at doses at low as 10 U. IL-10 also efficiently prevented the hypothermia generated by the injection of 100 micrograms LPS. Finally, pretreatment with a single injection of 1,000 U IL-10 completely prevented the mortality consecutive to the challenge with 500 micrograms LPS, a dose that was lethal in 50% of the control mice. We conclude that IL-10 inhibits in vivo TNF secretion and protects against the lethality of endotoxin in a murine model of septic shock.

Animals↗
PubMed1990

Increased expression of Ia antigens on B cells after neonatal induction of lymphoid chimerism in mice: role of interleukin 4.

BALB/c mice rendered chimeric at birth by injection of 10(8) (A/J X BALB/c)F1 spleen cells develop a lupus-like autoimmune disease linked to the activation of donor B cells by host T cells. As in vitro studies previously indicated that interleukin 4 (IL4) was a mediator of the interactions between T and B cells, we analyzed the intensity of Ia antigen expression on B cells of chimeric mice. Flow cytometric analysis with anti-Ia monoclonal antibodies (mAb) revealed that B cells from spleens and lymph nodes of 2-week-old chimeric BALB/c mice displayed a two- to threefold increase in membrane Ia antigen expression, this increase still being present in spleens of 30-week-old animals. An increase in Ia antigen expression was also found in the small number of donor B cells detected in spleens and lymph nodes of chimeric mice. IL4 was the major stimulus leading to increased B cell Ia antigen expression, as this phenomenon was substantially prevented by in vivo treatment of chimeric mice with the anti-IL4 11B11 mAb. In vitro experiments revealed that host splenic T cells of chimeric mice, while unable to generate anti-donor cytotoxic T lymphocytes, secreted significant amounts of IL 4 when stimulated in mixed lymphocyte cultures (MLC) with donor alloantigens. This IL4 secretion led to an increased expression of Ia antigens on donor-type F1 B cells present in MLC. No significant increase in Ia antigen expression was found on syngeneic BALB/c B cells co-cultured with T cells from chimeric mice unless A/J B cells were added to the cultures. Taken together, these findings indicate that increased Ia antigen expression on donor B cells is induced by IL4 secreted by anti-donor T cells. IL4 released in this setting also leads to increased Ia antigen expression on host B cells through a bystander effect.

Animals↗
PubMed1990

Persistence of anti-donor allohelper T cells after neonatal induction of allotolerance in mice.

BALB/c mice rendered tolerant to A/J alloantigens by neonatal injection of 10(8) (A/J X BALB/c)F1 spleen cells develop an autoimmune disease associated with a polyclonal activation of donor B cells. To study the mechanisms leading to donor B cell activation in tolerant mice, we prepared mixed lymphocyte cultures (MLC) between splenic T cells from neonatally injected mice and donor-type (A/J X BALB/c)F1 or third-party (C57BL/6 X BALB/c)F1 B cells. T cells from tolerized mice were unable to generate cytotoxic T lymphocytes, to proliferate or to secrete interleukin (IL)2 after stimulation with donor alloantigens in MLC. These T cell responses were present after MLC with third-party antigens, but were of lower intensity than those generated by control BALB/c T cells. In contrast, T cells from tolerized mice stimulated immunoglobulin production by donor-type (A/J X BALB/c)F1 B cells much more powerfully than T cells from control BALB/c mice. The stimulation of donor-type (A/J X BALB/c)F1 B cells was polyclonal, as attested by the levels of anti-hapten and anti-DNA antibodies in the MLC supernatants. IgM was the dominant isotype secreted in vitro, but IgG1 and IgG3 were also produced in significant amounts. Lysis experiments indicated that the T cells responsible for F1 B cell stimulation in MLC were CD4+ host T cells. These T helper cells were alloreactive since they did not stimulate syngeneic BALB/c B cells, and their effect on donor B cells was specifically blocked by anti-donor Ia monoclonal antibodies. Addition of anti-IL 4 monoclonal antibody to MLC between T cells from tolerant mice and (A/J X BALB/c)F1 B cells almost completely abolished the production of IgG1, but not that of IgM or IgG3. Taken together, these findings indicate that neonatal injection of alloantigens in BALB/c mice induces a state of dissociated tolerance, with unresponsiveness of anti-donor T cells secreting IL 2 on the one hand, and persistence of T cells responsible for B cell help and IL 4 secretion on the other hand.

Animals↗