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S Sozzani

Publications and source records attributed to S Sozzani.

At least 127 records · Page 7Linked to original sources
PubMed1994

Rapid induction of arachidonic acid release by monocyte chemotactic protein-1 and related chemokines. Role of Ca2+ influx, synergism with platelet-activating factor and significance for chemotaxis.

Monocyte Chemotactic Protein-1 (MCP-1), a member of the Cys-Cys branch of the chemokine superfamily, induced a mepacrine- and manoalide-sensitive increase in the release of [3H]arachidonic acid from prelabeled human monocytes and monocytic THP-1 leukemic cells. The effect was rapid (<30 s), reached maximum at optimal chemotactic concentrations, and was completely blocked by pretreatment of monocytes with Bordetella pertussis toxin. A specific antiserum and heat inactivation blocked the induction of arachidonic release by MCP-1. No [3H]arachidonic acid release was observed in the absence of Ca2+ influx (5 mM EGTA or 5 mM Ni2+) or in monocytes loaded with a Ca(2+)-buffering agent. However, using ionophore-permeabilized monocytes and controlled intracellular Ca2+ concentration it was possible to dissociate MCP-1-induced Ca2+ influx from [3H]arachidonic acid release. Thus, the MCP-1-induced increase in [Ca2+]i is necessary but not sufficient for arachidonic acid accumulation. Phospholipase A2 inhibitors (mepacrine, p-bromophenacyl bromide, and manoalide) blocked monocyte polarization and chemotaxis induced by MCP-1. The related Cys-Cys chemokines RANTES and LD78/MIP1 alpha also induced a rapid release of [3H]arachidonic acid, and their chemotactic activity was blocked by phospholipase A2 inhibitors. Brief (5 min) pretreatment of monocytes with platelet-activating factor amplified MCP-1-induced arachidonic acid release and, at MCP-1 suboptimal concentrations, synergized in inducing monocyte migration. Since MCP-1 and platelet-activating factor are induced concomitantly by inflammatory cytokines in monocytes and endothelial cells, we speculate that the observed synergism may have in vivo relevance. The results presented here show that the Cys-Cys chemokines MCP-1, LD78/MIP1 alpha, and RANTES cause rapid release of arachidonic acid in monocytes and that this may be important in inducing monocyte chemotaxis.

Arachidonic Acid↗
PubMed1994

Induction of natural killer cell migration by monocyte chemotactic protein-1, -2 and -3.

Under certain physiological and pathological conditions, natural killer (NK) cells rapidly accumulate in tissues. Chemokines are an essential component of the current paradigm of leukocyte recruitment. The present study was designed to investigate the responsiveness of NK cells to the prototypic C-C chemokine, monocyte chemotactic protein-1 (MCP-1). MCP-1 induced migration across filters of interleukin (IL)-2-activated NK cells, whereas it was a weak attractant for unstimulated cells. Maximal induction of migration required a positive concentration gradient between the lower and the upper compartment of the chemotaxis chamber. Preliminary characterization of the MCP-1 receptor on NK cells indicated that the chemotactic response to MCP-1 was blocked by pre-treatment of cells with Bordetella pertussis toxin, and MCP-1 but not IL-8 displaced 125I-labeled MCP-1 from IL-2-activated NK cells. The related chemokines MCP-2 and MCP-3 were also active--though less potent--attractants for activated NK cells. Thus the spectrum of action of MCP-1, -2 and -3 encompasses NK cells and chemokines are likely to play a role in regulating extravasation of these cells.

Binding, Competitive↗
PubMed1994

Species-specificity of monocyte chemotactic protein-1 and -3.

The present study was aimed at defining the activity of human and mouse monocyte chemotactic protein-1 (MCP-1) on homologous and heterologous mononuclear phagocytes. Human natural and recombinant MCP-1 and mouse natural MCP-1/JE were tested as chemoattractants on human blood monocytes and mouse peritoneal macrophages. The human and murine cytokines were equiactive on human monocytes. Human MCP-1 was active on mouse macrophages but the maximal chemotactic effect elicited was about half that of human cells or of mouse MCP-1/JE or of reference chemoattractants. Human MCP-3, a recently identified member of the C-C chemokine family, with high sequence similarity to MCP-1/JE, was also active on mouse mononuclear phagocytes, though less so than mouse MCP-1/JE. These results caution against under-estimating the potential of MCPs when the human chemokines are applied in mice.

Animals↗
PubMed1993

Retinoic acid and cyclic AMP synergistically induce the expression of liver/bone/kidney-type alkaline phosphatase gene in L929 fibroblastic cells.

In L929 mouse fibroblastic cells, liver/bone/kidney type alkaline phosphatase (L/B/K-ALP) enzymic activity is induced by all-trans-retinoic acid at concentrations between 10(-6) and 10(-5) M. At lower concentrations, retinoic acid is incapable of inducing this enzymic activity per se, but increases cyclic AMP (cAMP)-mediated induction. This effect is observed after incubation of the retinoid with dibutyryl cAMP, 8-bromo cAMP or forskolin. The synergism is dependent on the order of addition of retinoic acid and the activator of the cAMP pathway. Contemporaneous addition of the two agents, or addition of cAMP prior to retinoic acid (but not addition of retinoic acid before cAMP), is necessary to produce this synergistic interaction. The synergism results in increased steady-state levels of L/B/K-ALP mRNA and it is the consequence of increased transcriptional activity of the gene. The expression of the mouse L/B/K-ALP gene is regulated by the presence of two leader exons, 1A and 1B, resulting in the synthesis of two alternatively spliced mRNAs that are different only in part of their 5' untranslated region [Studer, Terao, Giannì and Garattini (1991) Biochem. Biophys. Res. Commun. 179, 1352-1360]. PCR amplification and nuclear run-on experiments performed using probes specific for each leader exon demonstrate that treatment of these cells with retinoic acid, forskolin or dibutyryl cAMP, and with the combination of the retinoid and one of the cAMP-elevating agents, leads to the accumulation of nascent and mature L/B/K-ALP mRNA containing exon 1B. The synergistic induction of the transcription of the L/B/K-ALP gene is well correlated with quantitative and qualitative changes of retinoic-acid-receptor mRNAs mediated by cAMP.

Alkaline Phosphatase↗
PubMed1993

Receptor-activated calcium influx in human monocytes exposed to monocyte chemotactic protein-1 and related cytokines.

Stimulation of human monocytes with monocyte chemotactic protein-1 (MCP-1) resulted in an increase of [Ca2+]i. The [Ca2+]i rise was dependent on external Ca2+, could be reconstituted by the addition of external Ca2+ and was blocked by Ni2+. Agonist-stimulated Ca2+ influx was demonstrated directly by the use of Mn2+: in the presence of extracellular Mn2+, MCP-1 and FMLP stimulated a dose-dependent quench in fluorescence of Fura-2-loaded monocytes. This quench was the result of stimulation of Mn2+ influx and was blocked by Ni2+ and by the Ca2+ channel inhibitor SC38249. Pretreatment of monocytes with verapamil and nifedipine or high depolarizing [K+] had no effect. MCP-1 did not induce production of inositol triphosphate nor turnover of phosphatidylinositol 4,5-biphosphate. Collectively, these results show that MCP-1 does not induce discharge of intracellular stores. This chemokine stimulates divalent cation entry (Ca2+ or Mn2+) by a mechanism independent of changes in [Ca2+]i, unrelated to voltage-dependent Ca2+ channels and presumably involving receptor-activated channels. In addition to MCP-1, also two other members of the chemokine Cys-Cys family, RANTES and MIP-1 alpha, stimulated [Ca2+]i increase. Exposure of human monocytes to either RANTES or MIP-1 alpha, had no effect on a subsequent stimulation by MCP-1. On the contrary, MCP-1 cross-desensitized monocytes for a subsequent stimulation with RANTES and MIP-1 alpha. These results suggest a certain level of receptor sharing among members of the Cys-Cys chemokine family.

Calcium↗
PubMed1992

Modulation of granulocyte survival and programmed cell death by cytokines and bacterial products.

Mature circulating polymorphonuclear cells (PMN) have the shortest half-life among leukocytes and undergo rapid programmed cell death in vitro. In this study, we have examined the possibility that inflammatory signals (cytokines and bacterial products) can regulate PMN survival. PMN in culture were found to rapidly die, with percentages of survival at 24, 48, 72, and 96 hours of 97.3% +/- 1.9%, 36.8% +/- 5.3%, 14.5% +/- 3.1%, and 4.2% +/- 2.9%, respectively (mean +/- SE of 20 different donors). PMN incubated with interleukin-1 beta (IL-1 beta), tumor necrosis factor, granulocyte-macrophage colony-stimulating factor (CSF), granulocyte-CSF, and interferon-gamma (IFN-gamma), but not with prototypic chemoattractants (fMLP, recombinant C5a, and IL-8), showed a marked increase in survival, with values ranging at 72 hours of incubation from 89.5% +/- 5.8% for IL-1 beta to 47.6% +/- 6.4% for IFN-gamma. The calculated half-life was 35 hours for untreated and 115 hours for IL-1-treated PMN. PMN activated with lipopolysaccharide (LPS) or inactivated streptococci also showed a longer survival compared with untreated cells (94.4% +/- 3.2% and 95.5% +/- 2.4%, respectively, at 72 hours). PMN surviving in response to LPS or IL-1 beta retained the capacity to produce superoxide anion when treated with phorbol esters or fMLP. All inducers of PMN survival protect these cells from programmed cell death because they reduced cells with morphologic features of apoptosis and the fragmentation of DNA in multiples of 180 bp. Thus, certain cytokines and bacterial products can prolong PMN survival by interfering with the physiologic process of apoptosis. Prolongation of survival may be important for the regulation of host resistance and inflammation, and may represent a crucial permissive step for certain cytokines and microbial products that activate gene expression and function in PMN.

Apoptosis↗
PubMed1992

Propranolol, a phosphatidate phosphohydrolase inhibitor, also inhibits protein kinase C.

Propranolol, a beta-adrenergic receptor antagonist, also inhibits phosphatidate phosphohydrolase, the enzyme that converts phosphatidic acid into diacylglycerol. This latter effect has prompted recent use of propranolol in studies examining the importance of diacylglycerol and phosphatidic acid in cellular signalling events. Here, we show that propranolol is also an inhibitor of protein kinase C. At concentrations greater than or equal to 20 microM, propranolol reduced [3H]phorbol dibutyrate binding (IC50 = 200 microM) and phorbol myristate acetate-stimulated superoxide anion release (IC50 = 130 microM) in human neutrophils. Scatchard analysis showed that propranolol lowers the number of phorbol diester binding sites without significantly affecting their affinity. In vitro kinetic analysis, performed in a mixed micellar assay with protein kinase C purified from human neutrophils, suggested a competitive inhibition of propranolol with the cofactor phosphatidylserine. Complex kinetic patterns were observed with respect to diacylglycerol and ATP, approximating competitive and noncompetitive inhibition, respectively. Taken together, these results suggest that the drug interacts at the level of the regulatory domain of the enzyme. Fifty % inhibition occurred at approximately 150 microM propranolol. Similar levels of inhibition were obtained using exogenous (histone) and endogenous (p47-phox, a NADPH oxidase component) substrates. Protein kinase C-alpha and protein kinase C-beta, two protein kinase C isozymes present in human neutrophils, were inhibited by propranolol in a comparable manner. In the range of concentrations tested (30-1000 microM), neither cAMP-dependent protein kinase nor neutrophil protein tyrosine kinases were affected. The racemic form of propranolol and the (+) and the (-) stereoisomers were equally active, and other beta-adrenergic receptor antagonists (pindolol) and agonists (isoproterenol) were inactive. This suggests that the inhibitory action of propranolol on protein kinase C is related to the amphipathic nature of the drug rather than to its beta-adrenergic receptor blocking ability. Analogs of propranolol were synthesized and found to be more potent protein kinase C inhibitors, with IC50 values in the 10-20 microM range. We conclude that the ability of propranolol to inhibit both protein kinase C and PA phosphohydrolase complicates interpretation of results when this drug is used in signal transduction studies. In addition, propranolol may be a useful prototype for the synthesis of new protein kinase C inhibitors.

Cells, Cultured↗
PubMed1992

Galanin reduces PDBu-induced protein phosphorylation in rat ventral hippocampus.

The effect of galanin (GAL) on basal and phorbol-12,13-dibutyrate (PDBu) induced protein phosphorylation in rat ventral hippocampal miniprisms was investigated. GAL (0.5, 1 and 2 microM) inhibited PDBu stimulation in a concentration-dependent manner without altering basal protein phosphorylation. This inhibitory effect was prevented by the GAL antagonist galantide. GAL did not affect either the activity of protein kinase C (PKC) from rat brain or basal phosphorylation in ventral hippocampal hippogenates, suggesting that it did not directly modulate PKC activity. Depolarization of miniprisms from ventral hippocampi by 18 mM K+ prevented the effect of GAL on PDBu-induced phosphorylation. The results indicate that GAL indirectly regulates neuronal protein phosphorylation by a GAL receptor-mediated action.

Animals↗
PubMed1992

The origin and function of tumor-associated macrophages.

Tumor-associated macrophages (TAM) have a complex relationship with the neoplastic cells of the tumor. On the one hand, the two cell types produce reciprocal growth factors and may be considered to have a symbiotic relationship. On the other hand, TAM can be activated to inhibit tumor growth and destroy neoplastic cells. Here, Alberto Mantovani and colleagues describe this delicate balance and the prospects for its therapeutic manipulation.

Animals↗
PubMed1991

The signal transduction pathway involved in the migration induced by a monocyte chemotactic cytokine.

Recombinant monocyte-chemotactic and activating factor (rMCAF; alternative acronyms MCP-1, TDCF, human JE) induced migration of human monocytes across polycarbonate or nitrocellulose filters. Maximal induction of migration was observed at a concentration of 10 ng/ml (10(-9) M). Checkerboard analysis revealed that rMCAF elicited true gradient-dependent chemotactic migration, although a gradient independent chemokinetic effect was observed at low concentrations (1-5 ng/ml). rMCAF caused a rapid (less than 5 s) and transient (approximately 1.5 min) increase of free cytosolic Ca2+ ions, as assessed by the fura-2 probe. No Ca2+ increase was detected in neutrophils or lymphocytes stimulated by rMCAF. Studies conducted in the absence of extracellular Ca2+ or in the presence of Ni2+ (an inhibitor of Ca2+ influx) suggested that the increase of intracellular Ca2+ induced by rMCAF is dependent on the influx of extracellular Ca2+ through plasma membrane channels. Bordetella pertussis toxin inhibited the intracellular Ca2+ elevation and chemotaxis caused by rMCAF. The possible involvement of Ca(2+)-dependent protein kinases in rMCAF signaling pathway(s) was explored using inhibitors. Inhibitors of GMP-dependent kinase and myosin L chain kinase had no effect on rMCAF-induced monocyte migration. In contrast, protein kinase C/cAMP-dependent kinase inhibitors (such as, C-I, H-7, HA-1004, KT5720, and Staurosporine) markedly decreased rMCAF induced chemotaxis suggesting the involvement of a serine/threonine protein kinase, possibly protein kinase C, in rMCAF signaling pathway.

Calcium↗
PubMed1991

Phosphatidic acid as a second messenger in human polymorphonuclear leukocytes. Effects on activation of NADPH oxidase.

Receptor-mediated agonists, such as FMLP, induce an early, phospholipase D (PLD)-mediated accumulation of phosphatidic acid (PA) which may play a role in the activation of NADPH oxidase in human PMN. We have determined the effect of changes in PA production on O2 consumption in intact PMN and the level of NADPH oxidase activity measured in a cell-free assay. Pretreatment of cells with various concentrations of propranolol enhanced (less than or equal to 200 microM) or inhibited (greater than 300 microM) PLD-induced production of PA (mass and radiolabel) in a manner that correlated with enhancement or inhibition of O2 consumption in PMN stimulated with 1 microM FMLP in the absence of cytochalasin B. The concentration-dependent effects of propranolol on FMLP-induced NADPH oxidase activation was confirmed by direct assay of the enzyme in subcellular fractions. In PA extracted from cells pretreated with 200 microM propranolol before stimulation with 1 microM FMLP, phospholipase A1 (PLA1)-digestion for 90 min, followed by quantitation of residual PA, showed that a minimum of 44% of PA in control (undigested) sample was diacyl-PA; alkylacyl-PA remained undigested by PLA1. Propranolol was also observed to have a concentration-dependent enhancement of mass of 1,2-DG formed in PMN stimulated with FMLP. DG levels reached a maximum at 300 microM propranolol and remained unchanged up to 500 microM propranolol. However, in contrast to PA levels, the level of DG produced did not correlate with NADPH oxidase activation. Exogenously added didecanoyl-PA activated NADPH oxidase in a concentration-dependent manner (1-300 microM) in a reconstitution assay using membrane and cytosolic fractions from unstimulated PMN. In addition, PA synergized with SDS for oxidase activation. Taken together, these results indicate that PA plays a second messenger role in the activation of NADPH oxidase in human PMN and that regulation of phospholipase D is a key step in the activation pathway.

Diglycerides↗
PubMed1990

In vivo effects of cyclosporin A on murine B-cells responding to type III pneumococcal polysaccharide.

The effect of cyclosporin A (CSA) on the antibody response to pneumococcal polysaccharide type III (a T-independent class 2 antigen) was investigated in mice. A single oral CSA administration (50 mg/kg) was able to depress (40%) the primary antibody response evaluated as spleen plaque-forming cells. Repeated treatments (12-50 mg/kg x 5) resulted in a higher degree of inhibition (80%) of anti-SIII response. Both single and repeated CSA treatments were active only when administered concomitantly with or after immunization, whereas no effects were seen with drug pretreatment. Comparable inhibitions of anti-SIII response were observed in control and nude mice suggesting a direct effect of CSA on B-cells.

Administration, Oral↗
PubMed1988

Modulation by suramin of NK and monocytic cell-mediated cytotoxicity in human and murine cells.

The in vitro effects of suramin, a compound recently tested in AIDS treatment, were investigated on human and murine NK and monocyte macrophage cytotoxicity and monocyte migratory ability. In a short-term, TNF-dependent assay, pre-exposure (4-18 h) to 100-400 micrograms/ml suramin was associated with a markedly increased cytotoxicity by human monocytes and murine-elicited peritoneal macrophages, paralleled by a greater cytotoxic capacity in the supernates of these effectors. Preincubation with the same pharmacological suramin concentrations also resulted in enhanced spontaneous and directed migration in monocytic cells. Suramin-preincubated human PBL and murine splenocytes were unchanged in their basal NK cytotoxicity but exhibited a deficient response to IFN. Pre- and post-incubations with suramin resulted in increased macrophagic cytotoxicity for TNF-insensitive targets. Conversely, postincubation of effectors with the drug at 100-400 micrograms/ml was associated with profound decreases in both NK and TNF-mediated macrophagic cytotoxicities, and prior exposure to suramin of macrophagic supernates resulted in reduced cytotoxic activity. The mechanisms involved in the complex modulatory activity of suramin for monocyte macrophages and NK cells and the possible therapeutic implications of these findings are discussed.

Animals↗
PubMed1988

In vitro modulation of human monocytes functions by RU 41740 (Biostim).

The in vitro effects of RU 41740, a mixture of two glycoproteins extracted from K. pneumoniae and possessing immunomodulatory activity, on human monocyte's cytotoxic activity, migratory capacity and monokine production were investigated. Exposure to RU 41740 in nanogram concentrations was associated with rapid increases in IL-1 and TNF production and marked augmentation in the monocytes' killing of TNF-sensitive targets, whereas killing of TNF-insensitive targets required longer exposures to microgram concentrations of this drug. Using otherwise effective treatment conditions, RU 41740 did not directly affect monocyte's spontaneous and FMLP-induced migration. The possible role of mononuclear cells stimulation and increased production of effector and regulatory monokines in the immunomodulatory activity of this product is addressed.

Adjuvants, Immunologic↗
PubMed1988

Stimulation of natural host defence mechanisms in rodents by nesosteine.

The effect of Nesosteine, a novel mucolytic agent, on natural host resistance mechanisms was investigated in different organs of mice and rats. Single or repeated administrations of nesosteine by the i.v. or oral route (per os) were associated with significant increases in lung and spleen NK-mediated cytotoxicity, and in alveolar and peritoneal macrophages direct cytotoxicity. In both species the dose-response curve was bell-shaped, and optimal activity on both parameters seen at 1 mg/kg i.v. x 1, 100 mg/kg per os x 1 or 20 mg/kg per os x 5. Increases of at least 100% in lung NK and alveolar macrophages cytotoxicity were found in mice 48 h after single oral dosing at 100 mg/kg. The possible importance of Nesosteine immunostimulatory capacity in the activity of this compound in chronic hypersecretive bronchopulmonary disorders is discussed.

Administration, Oral↗