Compared results of random and HLA DR semi-identical transfusion protocols.
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Blood Transfusion↗
Biomedical subjects
G Lemaire
Publications and source records attributed to G Lemaire.
Quenching of the tyrosyl free radical of ribonucleotide reductase by nitric oxide. Relationship to cytostasis induced in tumor cells by cytotoxic macrophages.
Nitric oxide (NO) synthesized by macrophages inhibits tumor cell replication. NO also inhibits ribonucleotide reductase, an enzyme essential for DNA synthesis, probably by quenching the catalytically active tyrosyl free radical of its R2 subunit. The role of this inhibition in NO-mediated cytostasis was thus evaluated. After a 4-h coculture with macrophages, quenching of the radical was demonstrated by electron paramagnetic resonance spectroscopy in transfected L1210-R2 cells over-expressing the R2 protein. Pronounced cytostasis was simultaneously observed. A NO synthase inhibitor greatly reduced both phenomena. Target cells withdrawn from macrophages partially recovered from cytostasis and radical loss within 90 min. Deoxyribonucleosides added to by-pass ribonucleotide reductase inhibition efficiently reversed cytostasis of K-562 cells. After a 24-h coculture, the quenched tyrosyl radical still reappeared in L1210-R2 cells withdrawn from macrophages, but DNA synthesis did not resume. Moreover, deoxyribonucleosides marginally reversed overnight cytostasis of K-562 cells mediated by macrophages but were efficient against cytostasis induced by hydroxyurea, a ribonucleotide reductase inhibitor. Autocrine cytostasis observed early in TA3-H2 cells committed to produce NO was closely correlated with quenching of the tyrosyl radical but not with formation of dinitrosyl-iron complexes. We thus propose that NO-dependent cytostasis begins with a rapid and reversible inhibition of ribonucleotide reductase, progressively reinforced by other, long-lasting antiproliferative effects.
Amino Acid Oxidoreductases↗
Role of calcium in the activation of mouse peritoneal macrophages: induction of NO synthase by calcium ionophores and thapsigargin.
Bacterial lipopolysaccharide (LPS) has been recognized as one of the most potent activating signals for mouse peritoneal macrophages. In macrophages primed by interferon-gamma (IFN-gamma) or trehalose dimycolate (TDM), LPS induces NO synthase and the events associated with a high nitric oxide output: antitumor and antiparasitic activities. In the present report, it is shown that drugs (calcium ionophores or thapsigargin) which elevate the concentration of cytosolic calcium, [Ca2+]i, induce NO synthase and antitumor activities in primed macrophages, mimicking LPS action. Calcium ionophores and thapsigargin trigger NO synthase activity in macrophages primed in vivo by TDM, in thioglycollate-elicited macrophages primed in vitro by IFN-gamma, and in IFN-gamma-treated EMT6 adenocarcinoma cells. However, activation of TDM-primed macrophages by LPS does not seem to involve calcium fluxes: (i) no change in [Ca2+]i was detectable in TDM-primed macrophages loaded with Fura-2 and exposed to LPS, and (ii) activation of TDM-primed macrophages by LPS can be obtained in the presence of 4 mM EGTA. NO synthase expression is thus controlled in primed macrophages by two different pathways; calcium ionophores can replace LPS but do not act through the same intracellular cascade.
Amino Acid Oxidoreductases↗
LPS-induced activation of primed murine peritoneal macrophages is modulated by prostaglandins and cyclic nucleotides.
Murine peritoneal macrophages primed in vivo by trehalose dimycolate (TDM) express cytostatic activity against tumor cells after treatment in vitro with 10 ng/ml lipopolysaccharide (LPS) during a 4-hr period (activation step). There is a strict correlation (P < 0.0001) between acquisition of antitumoral activity and induction of NO synthase quantified by its end products citrulline and NO2-. LPS also stimulates the release of cyclooxygenase products which exert a retroinhibitory action on NO synthase and cytostatic activities, as judged by an increase of both parameters by indomethacin (1 microM) and a decrease by externally added PGE2 (1 microM). LPS increases cellular and extracellular cAMP levels through an indomethacin-sensitive pathway, pointing to cAMP as a second messenger in the retroinhibitory action of LPS-induced prostaglandins. In fact, the addition of 8-bromo-cAMP or of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine during the activation step decreases NO synthase activity; however, at the same time these drugs increase the apparent efficiency of NO as an antitumor agent.
Amino Acid Oxidoreductases↗
Antiviral action of trehalose dimycolate against EMC virus: role of macrophages and interferon alpha/beta.
Preventive treatment of mice with trehalose 6,6' dimycolate (TDM), an immunomodulator of bacterial origin, enhances their resistance to encephalomyocarditis (EMC) virus infection. The protective effect of TDM is totally abolished by the injection of silica particles in mice, demonstrating the role of macrophages in the antiviral action of TDM. In vitro, peritoneal macrophages from mice treated with TDM (TDM-PM) exhibit an intrinsic antiviral activity against EMC virus, while resident peritoneal macrophages (RES-PM) are permissive to this virus. Greater amounts of interferon are detected in supernatants of cultures of TDM-PM than of RES-PM. Neutralization of interferon (IFN) by addition in vitro of anti-IFN alpha/beta serum markedly reduces the antiviral activity of TDM-PM. These results indicate that interferon alpha/beta is involved in the intrinsic anti-EMC virus activity of peritoneal macrophages from mice treated with TDM.
Animals↗
During their differentiation into macrophages, human monocytes acquire cytostatic activity independent of NO and TNF alpha.
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Cell Differentiation↗
Low response of BALB/c macrophages to priming and activating signals.
Trehalose dimycolate (TDM), a mycobacterial glycolipid, is a powerful macrophage-priming agent. However, its efficiency seems limited in the case of BALB/c mice. Peritoneal macrophages harvested from TDM-treated BALB/c mice did not control BCG growth in vitro as efficiently as similar macrophages from two other mouse strains, (B6 x D2)F1 and C57BL/6, which are respectively Bcgr and Bcgs. BALB/c macrophages elicited by TDM also exhibited a low capacity to produce hydrogen peroxide and, after activation by lipopolysaccharide (LPS), weak cytostatic activity against P815 mastocytoma cells. Finally, alkaline phosphodiesterase, a marker of resident and inflammatory macrophages, was still expressed at a high level in macrophages of BALB/c mice treated with TDM. Low responsiveness of BALB/c macrophages to stimuli was not observed with TDM only; activation for tumor cytotoxicity of thioglycolate-elicited macrophages from BALB/c mice required also higher doses of interferon-gamma, and LPS. L-Arginine-dependent production of nitric oxide was inducible in macrophages from BALB/c mice, but the conditions required for its induction were more stringent. Thus, the reduced antiproliferative effects of BALB/c macrophages may be due to uncomplete induction of NO synthase after suboptimal stimulation.
Amino Acid Oxidoreductases↗
Antiproliferative effects of NO synthase products.
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Amino Acid Oxidoreductases↗
Stimulation of antimycobacterial activity in mouse peritoneal macrophages by priming with trehalose dimycolate (TDM).
We examined the potential of two bacterial immunomodulators, trehalose dimycolate (TDM) and lipopolysaccharide (LPS), to stimulate the capacity of mouse peritoneal macrophages to control the growth of the intracellular bacterium, Mycobacterium tuberculosis BCG. Macrophages were obtained from mice innately susceptible (Bcgs) or resistant (Bcgr) to BCG infection. In all mouse strains tested (Bcgr and Bcgs), with the exception of BALB/c (Bcgs), TDM was sufficient to elicit macrophages with strong antimycobacterial activity in vitro. In BALB/c mice, the induction of anti-BCG activity required two signals, TDM and LPS, given in sequence. Our data suggest that additional gene(s), besides the Bcg locus, control macrophage resistance to BCG.
Animals↗
Alterations of ribonucleotide reductase activity following induction of the nitrite-generating pathway in adenocarcinoma cells.
The murine adenocarcinoma cell line TA 3 synthesized nitrite from L-arginine upon stimulation with gamma-interferon (IFN-gamma) associated with tumor necrosis factor (TNF), and/or bacterial lipopolysaccharide (LPS), but not with IFN-gamma, TNF, or LPS added separately. Induction of the NO2(-)-generating activity caused an inhibition of DNA synthesis in TA 3 cells. This inhibition was prevented by the L-arginine analog N omega-nitro-L-arginine, which inhibited under the same conditions nitrite production by TA 3 cells. The TA 3 M2 subclone, selected for enhanced ribonucleotide reductase activity, was found to be less sensitive than the wild phenotype TA 3 WT to the cytostatic activity mediated by the NO2(-)-generating system. Cytosolic preparations from TA 3 M2 cells treated for 24 or 48 h with IFN-gamma, TNF, and LPS exhibited a reduced ribonucleotide reductase activity, compared to untreated control cells. No reduction in ribonucleotide reductase activity was observed when N omega-nitro-L-arginine was added to treated cells. Addition of L-arginine, NADPH, and tetrahydrobiopterin into cytosolic extracts from 24-h treated TA 3 M2 cells triggered the synthesis of metabolic products from the NO2(-)-generating pathway. This resulted in a dramatic inhibition of the residual ribonucleotide reductase activity present in the extracts. The inhibition was reversed by NG-monomethyl-L-arginine, another specific inhibitor of the NO2(-)-generating activity. No L-arginine-dependent inhibition of ribonucleotide reductase activity was observed using extracts from untreated cells that did not express NO2(-)-generating activity. These results demonstrate that, in an acellular preparation, molecules derived from the NO2(-)-generating pathway exert an inhibitory effect on the ribonucleotide reductase enzyme. This negative action might explain the inhibition of DNA synthesis induced in adenocarcinoma cells by the NO2(-)-generating pathway.
Adenocarcinoma↗
[Musical expression and the psychotic child].
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Child↗
Modifications of glycosylation patterns in macrophages upon activation.
Activated macrophages, in contrast to inflammatory and resident macrophages, are able to inhibit the growth of intracellular pathogens and tumor cells. In order to understand the adaptative changes which allow macrophages to express antitumor activity, we compared, among several parameters, the glycoproteins of cytotoxic and non-cytotoxic macrophages. After activation of mouse peritoneal macrophages by two stimuli applied in a sequence (trehalose dimycolate in vivo, lipopolysaccharide in vitro), we observed that: (1) surface sialic acid residues (labeled by tritiated borohydride after treatment of intact cells in culture by periodate) were reduced by 37%; (2) total sialic acid, as measured by an adaptation to HPLC of the thiobarbituric assay, was reduced by 30%. Variations in the intensity of the labeling after periodate/borohydride treatment were especially pronounced for a few high-molecular-weight glycoproteins. Analysis of glycopeptides indicated that the reduction of sialylation was accompanied by a slight increase in the relative importance of high mannose-type oligosaccharides (glycopeptides sensitive to endoglycosidase H or retained on concanavalin A-Sepharose) but did not affect the ratio of the various anionic species separated on QAE-Sephadex. A reduced sialylation of glycans after activation may facilitate interactions of macrophages with microbes and tumor cells.
Animals↗
Cytostatic product(s) released by activated macrophages, unrelated to interleukin 1, tumor necrosis factor alpha, and interferon-alpha/beta.
Murine peritoneal macrophages activated for cytotoxicity by trehalose dimycolate in vivo and lipopolysaccharide in vitro released cytostatic factor(s) against EMT6 target cells, in 8-hr conditioned medium (CM). The cytostatic factor(s) completely blocked DNA synthesis by EMT6 cells within 16 hr. Other cell lines are less sensitive (P815 and R-L929) or resistant (KB and HT29) to the cytostatic effect of CM. The anti-proliferative activity of CM had a MW greater than 10,000 Da, as judged by ultrafiltration. It was destroyed by proteases and strongly inhibited by P815 cell product(s). Conditioned media from nonactivated macrophages were not cytostatic against EMT6 cells. No relationship was found between cytostatic factor(s) in CM and interleukin 1 (IL-1), tumor necrosis factor alpha (TNF-alpha), and interferon-alpha/beta (IFN-alpha/beta): the growth of EMT6 cells was unaffected by Hu.r.IL-is and Hu.r.TNF-alpha and was only slightly inhibited by IFN-alpha/beta. Furthermore, cytostatic CM contained low levels of TNF and IFN activities. Finally, antibodies raised against murine IFN-alpha/beta had no effect on the cytostatic activity of CM.
Animals↗
Dexamethasone inhibits antitumor potential of activated macrophages by a receptor mediated action.
The capacity to inhibit P815 mastocytoma growth was induced in macrophages elicited by trehalose dimycolate by a short in vitro treatment with 10 ng/ml LPS. Activation by LPS was associated with a 3 fold increase in the rate of glucose consumption by macrophages. Incubation of activated macrophages with the glucocorticoid dexamethasone (greater than or equal to 10(-8) M) for several hours (greater than or equal to 5 h) resulted in an inhibition of antitumoral activity and a decrease of glucose consumption. Hydrogen peroxide production is a property expressed by trehalose dimycolate-elicited macrophages independently of the presence of LPS. The capacity to release hydrogen peroxide upon triggering was not affected by a pretreatment of macrophages by dexamethasone. The antiglucocorticoid compound RU 38486, known to bind with a high affinity to glucocorticoid receptors without agonist effect, prevented the inhibitory actions of dexamethasone, indicating that these are receptor-mediated.
Animals↗
Macrophage activation by trehalose dimycolate requirement for an expression signal in vitro for antitumoral activity; biochemical markers distinguishing primed and fully activated macrophages.
It was possible to define the effects of trehalose dimycolate (TDM), a glycolipid extracted from Mycobacterium tuberculosis, on mouse peritoneal macrophages more precisely using endotoxin-free culture conditions. TDM-elicited macrophages, when assayed in vitro in the absence of endotoxin, were unable to limit tumor growth; however, after a short treatment (4 h) with low doses of lipopolysaccharide (LPS; 1-10 ng/ml), they exhibited a strong cytostatic capacity against P815 mastocytoma cells. Thus, TDM injected in vivo did not activate macrophages fully but it primed them to respond in vitro to low doses of LPS, which provided the final stimulus for activation to antitumor competence. Macrophages elicited by an injection of killed group C Streptococci were also in a primed state; in contrast, thioglycollate-elicited macrophages were in a nonreceptive state. Besides LPS, concanavalin A (5 micrograms/ml), MDP (0.2-1 microgram/ml) and the ionophore A23187 (5 microM) can deliver the activation signal to TDM-primed macrophages. Primed macrophages were found to express several biochemical markers previously described as specific for activated macrophages (low levels of alkaline phosphodiesterase and beta-galactosidase, for example) and, although they were not cytotoxic for tumor cells, they had the capacity to release large amounts of H2O2. However, when pulsed by LPS or MDP, primed macrophages responded by further modifications in their metabolism: the rate of glucose consumption and the labeling of glycoproteins by D-[2-3H]mannose were greatly increased and the secretion of a polypeptide of 22 kDa was enhanced. The activation-associated biochemical markers are thus acquired in two steps. The ability to produce activated oxygen species is expressed earlier than the antitumoral activity.
Animals↗
Modifications induced by activation to tumor cytotoxicity in the protein secretory activity of macrophages.
After biosynthetic radiolabeling, polypeptides secreted by macrophages were analyzed by electrophoresis on polyacrylamide gels in the presence of sodium dodecyl sulfate and fluorography. Comparative studies of various macrophage populations (inflammatory macrophages, primed and activated macrophages, resident macrophages) showed that secretory activity is elaborately controlled according to macrophage developmental and functional state. When young macrophages activated to cytotoxicity against tumor cells by an appropriate eliciting agent and culture in the presence of lipopolysaccharide were compared to mature resident macrophages devoid of antitumor activity, the following changes were observed in the protein secretion phenotype: (1) New polypeptides are expressed: the intensity of four bands was increased more than five-fold on one-dimensional gels and 17 new spots were detected on two-dimensional gels. (2) The production of several major polypeptides is repressed: six bands were strongly decreased on one-dimensional gels, and 11 major spots (or groups of spots) were lost on two-dimensional gels. (3) The charge microheterogeneity pattern exhibited by several polypeptides on two-dimensional gels is shifted towards less acidic species.
Animals↗
Importance, localization and functional properties of the cell-associated form of plasminogen activator in mouse peritoneal macrophages.
In inflammatory macrophages, plasminogen activator exists in two active forms, a soluble form released into the extracellular medium and a cell-associated form. This communication describes some properties of the cellular form of plasminogen activator, in intact macrophages and in cell lysates. Cellular plasminogen activator is a membrane protein, associated with the outer face of the plasma membrane; in intact macrophages, it participates in the activation of exogenous plasminogen and, thus, has to be considered as an ectoenzyme. A plasminogen activator activity can be detected in cell lysates (macrophage monolayers lysed in 0.1% Triton X-100) only when plasmin production is followed by the use of small synthetic substrates because a soluble inhibitor, released during extraction, blocks plasmin fibrinolytic activity. In these lysates, plasminogen activator molecules exist as high molecular weight unstable complexes exhibiting a high affinity for plasminogen.
Animals↗