Biomedical subjects

P Vassalli

Publications and source records attributed to P Vassalli.

At least 73 records · Page 4Linked to original sources

PubMed1990

Requirement of tumour necrosis factor for development of silica-induced pulmonary fibrosis.

The deposition of silica particles in the lung of man or experimental animals leads to silicosis, a disease of progressive respiratory failure caused by a fibrotic reaction. It has long been suspected that the phagocytosis of silica by pulmonary macrophages induces the secretion of fibrogenic factors. Several potentially fibrogenic cytokines released by macrophages have been identified, including interleukin-1 (IL-1), tumour necrosis factor-alpha (TNF), platelet-derived growth factor, basic fibroblast growth factor and transforming growth factor-beta (TGF-beta). Here we show that TNF plays an important part in silica-induced pulmonary fibrosis in mice in that (1) a single instillation of silica leads to a marked increase in the level of lung TNF messenger RNA which lasts for greater than 70 days, while there are no obvious changes in the amounts of IL-1 alpha or TGF-beta mRNAs; and (2) silica-induced collagen deposition is almost completely prevented by anti-TNF antibody, but is significantly increased by continuous infusion of mouse recombinant TNF.

Animals↗

PubMed1990

Tumor necrosis factor/cachectin and lymphotoxin gene expression in lymph nodes from lymphoma patients.

We investigated the mRNA content for tumor necrosis factor (TNF)/cachectin and lymphotoxin (LT) in tumoral tissues of a prospective series of 35 non-Hodgkin's (NHL) and 23 Hodgkin's (HL) lymphomas, to assess their postulated contribution to systemic symptoms. Total RNAs were extracted from diagnostic tissue specimens and submitted to Northern blot analysis, using specific TNF and LT cRNA probes. High amounts of TNF mRNA were found exclusively in NHL (12/35). The majority (9/12) of these were low grade B-cell NHL, which contained a uniform population of malignant cells. In contrast, abundant LT mRNA production was detected in most HL (21/23) and in 19 of 35 NHL. The highest LT mRNA levels were observed in high grade NHL and in lymphocytic predominant subtypes of HL specimens. A significant correlation was found between TNF/cachectin and LT gene expression in NHL and the presence of constitutional symptoms. The biologic and prognostic implications of these preliminary findings are presently unknown, but they demonstrate that lymphoma tissues sharing common histologic features are highly heterogeneous in their ability to synthesize cytokines susceptible to playing a role in the growth control of malignant cells. These results suggest that the evaluation of TNF/cachectin and LT production in lymphomas may help to elucidate the mechanisms of tumoral fever and cachexia.

Blotting, Northern↗

PubMed1990

Kappa B-type enhancers are involved in lipopolysaccharide-mediated transcriptional activation of the tumor necrosis factor alpha gene in primary macrophages.

We have explored the cis-acting elements necessary for the LPS-mediated activation of the mouse TNF-alpha promoter by transfecting a set of 5' deletion mutants linked to the CAT reporter gene into primary bone marrow-derived macrophages. A major drop in inducibility by LPS was seen upon deletion of a region mapping between nt -655 and nt -451. Gel retardation assays revealed that LPS induced the appearance in this region of several specific DNA-protein complexes mapping to sequence motifs with strong homology to the kappa B enhancer. Constructs containing two or more copies of one of the kappa B enhancer motifs linked to a heterologous promoter were inducible by LPS. Additional deletion of a region between nt -301 and nt -241, which contains a MHC class II-like "Y box" and formed a Y box-specific complex with a protein whose concentration was increased by LPS, caused a nearly complete loss of inducibility by LPS. We speculate that NF-kappa B and/or related proteins are involved in the LPS-induced transcriptional activation of the TNF-alpha gene, and that factors interacting with the Y box can additionally modulate the activity of the gene in macrophages.

Animals↗

PubMed1990

Significance of cytokine production and adhesion molecules in malarial immunopathology.

The pathological expression in malaria infection depends largely on immunopathologic responses induced by the parasite. In the past few years, we have attempted to analyze mechanisms by which inappropriate immune response to some malarial antigens can generate major complications of malaria and particularly neurovascular lesions. To this end, we have undertaken a study aimed at a more precise definition of immunopathological parameters of malaria infection, and more particularly those involved in cerebral malaria (CM). CM, the most severe complication of falciparum infection in man, represents a major problem of public health at the world level.

Animals↗

PubMed1990

Regulation of tumor necrosis factor alpha transcription in macrophages: involvement of four kappa B-like motifs and of constitutive and inducible forms of NF-kappa B.

This study characterizes the interaction of murine macrophage nuclear proteins with the tumor necrosis factor alpha (TNF-alpha) promoter. Gel retardation and methylation interference assays showed that stimulation of TNF-alpha gene transcription in peritoneal exudate macrophages was accompanied by induction of DNA-binding proteins that recognized with different affinities four elements related to the kappa B consensus motif and a Y-box motif. We suggest that the basal level of TNF-alpha expression in macrophages is due to the binding of a constitutive form of NF-kappa B, present at low levels in nuclei from resting thioglycolate exudate peritoneal macrophages, to some if not all of the kappa B motifs; we postulate that this constitutive form contains only the 50-kilodalton (kDa) DNA-binding protein subunits of NF-kappa B, not the 65-kDa protein subunits (P. Baeuerle and D. Baltimore, Genes Dev. 3:1689-1698, 1989). Agents such as glucocorticoids, which decrease TNF-alpha transcription, diminished the basal level of nuclear NF-kappa B. Stimulation of Stimulation of TNF-alpha transcription in macrophages by lipopolysaccharide, gamma interferon, or cycloheximide led to an increased content of nuclear NF-kappa B. This induced factor represents a different form of NF-kappa B, since it generated protein-DNA complexes of slower mobility; we propose that this induced form of NF-kappa B contains both the 50- and 65-kDa protein subunits, the latter ones being necessary to bind NF-kappa B to its cytoplasmic inhibitor in uninduced cells (Baeuerle and Baltimore, Genes Dev., 1989). In resting cells, this inducible form of NF-kappa B was indeed detectable in the cytosol after deoxycholate treatment. UV cross-linking experiments and gel retardation assays indicated that the inducible form of NF-kappa B is in a higher-order complex with other proteins.

Animals↗

PubMed1990

Subcutaneous perfusion of tumor necrosis factor induces local proliferation of fibroblasts, capillaries, and epidermal cells, or massive tissue necrosis.

Mouse recombinant tumor necrosis factor (TNF) (or its solvent alone as a control) was administered subcutaneously to mice by a cannula connected to an osmotic minipump. Perfusion at a rate of 35 ng/hr for seven days induced the formation of a tissue mass composed mainly of fibroblasts, collagen, and capillaries. Necrosis (apoptosis) of isolated fibroblasts was observed. Polymorphonuclear leukocytes were abundant after three to four days of perfusion but were absent later. The covering epidermis showed a hyperplastic reaction associated with necrosis of isolated keratinocytes. Perfusion at a rate of 170 ng/hr led, after four to five days, to a massive necrosis. Necrosis was completely prevented by rabbit anti-TNF IgG but not by anti-LPS IgG, irradiation, or administration of indomethacin.

Animals↗

PubMed1989

[Tumor necrosis factor (TNF) and pathology; its relationships with other cytokines].

Tumor necrosis factor (TNF) is a cytokine produced mainly by activated monocytes/macrophages. We review here data obtained in four experimental models analyzed in our laboratory: cerebral malaria, graft-versus-host disease, BCG infection, and bleomycin-induced pulmonary fibrosis. We have shown that the triggering of these pathological conditions requires activation of T lymphocytes and overproduction of TNF, since these syndromes are associated with increased production of TNF mRNA and can be prevented either by T-cell depletion or by in vivo administration of neutralizing anti-TNF antibodies. These observations suggest that TNF is a central mediator in various immunopathological conditions and thus widen the field of T-cell mediated pathology.

Animals↗

PubMed1989

Tumor necrosis factor/cachectin plays a key role in bleomycin-induced pneumopathy and fibrosis.

The role of TNF-alpha/cachectin in the pneumopathy elicited by bleomycin has been investigated. After a single intratracheal bleomycin instillation, an increase of the lung TNF-alpha mRNA level was evident, from days 5 to 15, as shown by Northern gel analysis of whole lung RNA. In contrast, lung IL-1-alpha and GM-CSF mRNA were not detectable. In mice passively immunized with rabbit anti-mouse TNF-alpha IgG, the bleomycin-induced collagen deposition, evaluated by the total lung hydroxyproline assay on day 15, was prevented. Depletion of the CD4 and CD8 T lymphocytes by an in vivo treatment with mAb prevented the bleomycin-induced increase of TNF mRNA level and fibrosis. After an administration of bleomycin in continuous intraperitoneal perfusion, the diffuse alveolar damage observed by light and electron microscopy was almost completely prevented by anti-TNF antibody. These results indicate that in response to bleomycin, the T lymphocytes induce, by an undefined mechanism, an increase of the pulmonary TNF production, which leads to alveolar damage, growth of fibroblast, and collagen deposition.

Animals↗

PubMed1989

Tumor necrosis factor and disease severity in children with falciparum malaria.

To investigate the role of tumor necrosis factor in Plasmodium falciparum infections, we measured serum concentrations of this cytokine in 65 Malawian children with severe falciparum malaria. Of these children (mean age, 5.3 years), 55 were unconscious and 10 had hypoglycemia at presentation. Although there was considerable overlap, the mean (+/- SEM) initial serum concentration of tumor necrosis factor was significantly higher in the 10 patients who died (709 +/- 312 pg per milliliter) than in the 55 who survived (184 +/- 32 pg per milliliter; P less than 0.02). The mortality rate increased with the concentration of tumor necrosis factor: at a level of less than 100 pg per milliliter, 1 of 24 patients died; at 100 to 500 pg per milliliter, 6 of 34 patients; and at more than 500 pg per milliliter, 3 of 7 patients. High concentrations of tumor necrosis factor were also associated with hypoglycemia (P less than 0.02), hyperparasitemia (P less than 0.002), age under three years (P less than 0.03), and severity of illness as measured by a prognostic index (P less than 0.0005). The highest serum concentrations of tumor necrosis factor were found in patients who died shortly after admission. The concentrations in cerebrospinal fluid were within the normal range in all patients. In serum samples obtained from 38 convalescent patients, the concentration of tumor necrosis factor declined to a mean of 16 +/- 3 pg per milliliter. We conclude that the level of tumor necrosis factor is frequently increased in patients with severe falciparum malaria, particularly in those with cerebral malaria or hypoglycemia. To determine whether it is important in the pathogenesis of the signs and symptoms of the disease requires further study.

Animals↗

PubMed1989

The inducing role of tumor necrosis factor in the development of bactericidal granulomas during BCG infection.

Granuloma formation in the liver of mice infected with BCG coincides with local TNF synthesis. Injection of rabbit anti-TNF antibody, after 1 or 2 weeks of infection, dramatically interferes with the development of granulomas (both in number and size, large epithelioid cells failing to appear) and subsequent mycobacterial elimination. Furthermore, fully developed BCG granulomas, after 3 weeks of infection, rapidly regress after anti-TNF treatment. Antibody treatment also prevents or suppresses accumulation of TNF mRNA and protein, which resumes after disappearance of the antibody. Peritoneal macrophages exposed to TNF transiently accumulate TNF mRNA, and show an enhanced increase in TNF mRNA in response to gamma interferon. We propose that TNF released from macrophages in the microenvironment of developing granulomas is involved in a process of autoamplification: acting in an autocrine or paracrine way, it enhances its own synthesis and release, thus favoring further macrophage accumulation and differentiation leading to bacterial elimination.

Animals↗

PubMed1989

Interleukin 1 and tumor necrosis factor-alpha additively increase the levels of granulocyte-macrophage and granulocyte colony-stimulating factor (CSF) mRNA in human fibroblasts.

Recombinant interleukin (IL) 1 beta and tumor necrosis factor/cachectin (TNF-alpha) induce, usually within 2 h, a dose-dependent increase in the levels of granulocyte-macrophage colony-stimulating factor (GM-CSF) and G-CSF mRNA in cultured human fibroblasts. Maximal induction is reached at about 4-8 h and usually last for at least 48 h. IL 1 beta and TNF have additive effects on the levels of GM- and G-CSF mRNA, and on the secretion of G-CSF activity into the culture medium. IL 1 alpha has the same additive effect that IL 1 beta has with TNF, but no additive effect with IL 1 beta. In contrast, the high basic level of M-CSF (CSF-1) mRNA shows little or lower variations in response to IL 1, TNF-alpha or both IL 1 and TNF-alpha also induce, with similar kinetics, an increase in IL 1 beta but not mRNA level. In contrast to what is observed with macrophages and endothelial cells, E. coli lipopolysaccharide does not modify the fibroblast CSF mRNA level up to 48 h of culture.

Colony-Stimulating Factors↗

PubMed1989

Monoclonal antibody against interferon gamma can prevent experimental cerebral malaria and its associated overproduction of tumor necrosis factor.

Experimental cerebral malaria (ECM), a lethal hyperacute neurological syndrome associated with high blood levels of tumor necrosis factor, develops in genetically susceptible (CBA/Ca) mice 7 days after infection with Plasmodium berghei ANKA strain. Injections of neutralizing monoclonal antibody against recombinant murine interferon gamma, not later than 4 days after infection, markedly reduced the incidence of ECM and the elevation in serum levels of tumor necrosis factor. This treatment prevented the cerebral lesions (plugging of brain vessels by monocytes, lymphocytes, and parasitized erythrocytes). In contrast, the extent of macrophage infiltration in lymphoid organs (which is a characteristic feature of mice developing ECM), as well as the course of infection, remained unaffected by the antibody treatment. Protected mice died at a later time of severe anemia and overwhelming parasitemia, the usual outcome of P. berghei infection in mice that are not susceptible to ECM. The present data indicate that interferon gamma constitutes an important link in the cytokine network that leads to brain vessel inflammation in experimental malaria. It is proposed that interferon gamma released by activated CD4+ T cells acts by augmenting both production and action of tumor necrosis factor.

Animals↗

PubMed1989

Tumor-necrosis factor and other cytokines in cerebral malaria: experimental and clinical data.

Evidence is presented here that tumor necrosis factor/cachectin (TNF), is of crucial importance in the pathogenesis of cerebral malaria. First, the central lesion of CM, hemorrhagic necrosis of cerebral vessels, corresponds to lesions observed during other pathological conditions associated with high serum TNF levels, such as endotoxemic shock or administration of TNF. Second, in both mouse and human, there is a close correlation between high serum TNF levels and CM. At least in mouse, high TNF levels and CM depend upon T lymphocytes of the CD4+ phenotype. Third, passive immunization against mouse TNF significantly prolongs the survival of P. berghei-infected CBA/Ca mice, and prevents the development of neurologic signs. Treatment with the anti-TNF antibody also prevents hemorrhagic necrosis of brain vessels. Fourth, in the mouse model, a cytokine cascade including at least GM-CSF, IL-3 and IFN-gamma is required for the elevation of TNF level. This cascade appears to involve two components: (a) a quantitative component: increased accumulation of macrophages results from the concomitant release of IL-3 and GM-CSF, and (b) a qualitative component: macrophage number has not only to be raised, but macrophages need to be activated by IFN-gamma. Fifth, metabolic parameters of CM and its main lesion in both mouse and human, i.e. the hemorrhagic necrosis of small brain vessels, correspond to the known properties of TNF.

Animals↗

PubMed1989

Involvement of tumour necrosis factor and other cytokines in immune-mediated vascular pathology.

Vascular endothelial cells are actively involved in coagulation and inflammation processes and appear to represent an important element in cell-mediated immune responses. In this paper, the possible role of endothelial cells as a target for immunopathological reactions was analyzed. Experimental neurovascular lesions were studied in a model of cerebral malaria, with particular attention to the role of cytokine interactions in vivo.

Animals↗

PubMed1989

Receptor-mediated phagocytosis by macrophages induces a calcium-dependent transient increase in c-fos transcription.

The transcription of the c-fos gene and the level of c-fos mRNA in mouse peritoneal macrophages are rapidly, strongly and transiently increased after Fc- and C3b-mediated phagocytosis, but not after phagocytosis of latex particles. In order to induce both phagocytosis and a rise in c-fos mRNA, binding to receptors must be followed by mobilization of Ca++ from intracellular Induction of c-fos transcription in macrophages by other agents acting through different intracellular "messengers', i.e. phorbol esters (protein kinase C), cholera toxin (cAMP) and dexamethasone (glucocorticoid receptor) also depends on intracellular Ca++. In all these conditions, induction of c-fos transcription is inhibited by the calmodulin antagonist W7, suggesting a common Ca++-dependent pathway for c-fos gene activation in macrophages.

Animals↗

PubMed1989

Presence of a very small population of Thy-1+, L3T4+ cells producing large amounts of IL-3 in young athymic nude mice.

A mixture of phorbol myristate acetate (PMA) and ionomycin was found to stimulate spleen and lymph node cells (LNC) from 6 to 8 week-old-athymic BALB/c nude mice, as well as from control +/+ mice, to secrete interleukin-3 (IL-3) in vitro. The specificity of the IL-3 bioassay was attested to by the use of rabbit anti-IL-3 antibodies, and by the detection of an accumulation of IL-3 mRNA. Cytotoxic treatment with relevant antibodies showed that the cells responsible for the IL-3 production in athymic nude mice was Thy-1+, L3T4+, Ly2-, while both L3T4+ and Ly 2+ cells produced IL-3 in control +/+ mice. Although the levels of IL-3 secreted by nude LNC varied among experiments, nude LNC were able to produce IL-3 at a level comparable to or higher than +/+ LNC. In addition, nude LNC consistently secreted two to three times more granulocyte-macrophage colony-stimulating factor (GM-CSF) than +/+ LNC, and the majority of GM-CSF secretion was dependent on the presence of L3T4+ cells. In contrast, IL-2 production by nude LNC was markedly limited. Since the flow microfluorometry analysis failed to demonstrate the presence of L3T4+ cells (less than 1%) in nude LNC, compared with 40-50% L3T4+ cells in +/+ LNC, our results suggest that athymic nude mice have a small population of Thy-1+, L3T4+ cells characterized by its ability to secrete IL-3 and GM-CSF at a very high rate.

Animals↗

PubMed1989

Pneumopathies of the graft-versus-host reaction. Alveolitis associated with an increased level of tumor necrosis factor mRNA and chronic interstitial pneumonitis.

Irradiated (CBA x B10)F1 hybrid mice were injected with parental T lymphocyte-depleted bone marrow cells, (BMC), or with parental BMC together with T lymphocytes in an amount inducing greater than 80% mortality by day 40. Recipients of T cell depleted BMC did not show any mortality or significant pulmonary alterations, whereas recipients of BMC with T lymphocytes showed an alveolitis during the acute phase of the graft-versus-host reaction (GVHR) (day 15 to 25), characterized by: (a) alveolar hemorrhages, (b) increase of the number of alveolar leukocytes, (c) platelet microthrombi, (d) damage of the alveolar endothelial and epithelial cells, (e) increase of the turnover rate of the alveolar cells as shown by 3HTdR labelling, (f) increase in cell number and protein content of the bronchoalveolar lavage. These lesions were severe in the B10 versus F1, but absent in the reciprocal CBA versus F1 GVHR combination. The alveolitis was associated with a marked increase in the level of tumor necrosis factor-alpha mRNA, as shown by Northern gel analysis of lung RNA and was partially prevented by passive immunization with a rabbit anti-mouse tumor necrosis factor-alpha antibody. Mice examined after 25 days of evolution (i.e., chronic GVHR) presented an interstitial pneumonitis characterized by the accumulation of mononucleated cells, resembling large granular lymphocytes, which infiltrated first the intima of the blood vessels, and subsequently the interstice and the bronchi. These data demonstrate that the GVHR alone (in the absence of chemotherapy or overt infection) can induce two types of pneumopathies, an alveolitis and an interstitial pneumonitis.

Animals↗

PubMed1988

Prevention of experimental cerebral malaria by anticytokine antibodies. Interleukin 3 and granulocyte macrophage colony-stimulating factor are intermediates in increased tumor necrosis factor production and macrophage accumulation.

IL-3 and granulocyte/macrophage colony stimulating factor (GM-CSF) are two cytokines released by activated T lymphocytes that stimulate the growth and differentiation of various hematopoietic cell lines, among which are macrophages. It has been shown that TNF/cachectin, another cytokine that is released mostly by activated macrophages, plays a central role in experimental cerebral malaria (CM), an acute and lethal neurological syndrome induced by Plasmodium berghei ANKA infection in CBA mice. Since CM requires functional CD4+ T lymphocytes to occur, we explored, by injecting rabbit antibodies to murine rIL-3 and/or GM-CSF, whether these cytokines are intermediates in the marked TNF release leading to CM. Treatment of infected mice with each antibody separately had no protective effect. In contrast, when both anti-rGM-CSF and anti-rIL-3 antibodies were injected together; (a) the occurrence of neurological syndrome was prevented in 90% of the cases; (b) the rise in serum TNF was prevented; and (c) macrophage accumulation in the spleen was significantly reduced. Murine CM appears to involve a cytokine cascade in which IL-3 and GM-CSF lead to the accumulation of TNF-releasing macrophages in vivo.

Animals↗