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Alberto Mantovani

Publications and source records attributed to Alberto Mantovani.

At least 91 records · Page 5Linked to original sources
PubMed2004

The chemokine system in diverse forms of macrophage activation and polarization.

Plasticity and functional polarization are hallmarks of the mononuclear phagocyte system. Here we review emerging key properties of different forms of macrophage activation and polarization (M1, M2a, M2b, M2c), which represent extremes of a continuum. In particular, recent evidence suggests that differential modulation of the chemokine system integrates polarized macrophages in pathways of resistance to, or promotion of, microbial pathogens and tumors, or immunoregulation, tissue repair and remodeling.

Animals↗
PubMed2004

Chemokines in the recruitment and shaping of the leukocyte infiltrate of tumors.

Leukocytes, and macrophages in particular, are an important component of the stroma of neoplastic tissues. Tumor-associated macrophages (TAM) have the properties of a polarized M2 population and are a key component of inflammatory circuits which promote tumor growth and progression. Chemokines play a key role in the recruitment and positioning of TAM and dendritic cells in tumors and contribute to shaping their functional properties. Chemokine-recruited and positioned tumor infiltrating leukocytes are a key component of inflammatory circuits which promote tumor progression.

Chemokines↗
PubMed2004

Anti-Aspergillus fumigatus efficacy of pentraxin 3 alone and in combination with antifungals.

The collectin pentraxin 3 (PTX3) is an essential component of host resistance to pulmonary aspergillosis. Here we examined the protective effects of administration of PTX3 alone or together with deoxycholate amphotericin B (Fungizone) or liposomal amphotericin B (AmBisome) against invasive aspergillosis in a murine model of allogeneic bone marrow transplantation. PTX3, alone or in combination with the polyenes, was given intranasally or parenterally either before, in concomitance with, or after the intranasal infection with Aspergillus fumigatus conidia. Mice were monitored for resistance to infection and parameters of innate and adaptive T-helper immunity. The results showed the following: (i) complete resistance to infection and reinfection was observed in mice treated with PTX3 alone; (ii) the protective effect of PTX3 was similar or superior to that observed with liposomal amphotericin B or deoxycholate amphotericin B, respectively; (iii) protection was associated with accelerated recovery of lung phagocytic cells and T-helper-1 lymphocytes and concomitant decrease of inflammatory pathology; and (iv) PTX3 potentiated the therapeutic efficacy of suboptimal doses of either antimycotic drug. Together, these data suggest the potential therapeutic use of PTX3 either alone or as an adjunctive therapy in A. fumigatus infections.

Amphotericin B↗
PubMed2004

Increased DC trafficking to lymph nodes and contact hypersensitivity in junctional adhesion molecule-A-deficient mice.

Junctional adhesion molecule-A (JAM-A) is a transmembrane adhesive protein expressed at endothelial junctions and in leukocytes. In the present work, we found that DCs also express JAM-A. To evaluate the biological relevance of this observation, Jam-A(-/-) mice were generated and the functional behavior of DCs in vitro and in vivo was studied. In vitro, Jam-A(-/-) DCs showed a selective increase in random motility and in the capacity to transmigrate across lymphatic endothelial cells. In vivo, Jam-A(-/-) mice showed enhanced DC migration to lymph nodes, which was not observed in mice with endothelium-restricted deficiency of the protein. Furthermore, increased DC migration to lymph nodes was associated with enhanced contact hypersensitivity (CHS). Adoptive transfer experiments showed that JAM-A-deficient DCs elicited increased CHS in Jam-A(+/+) mice, further supporting the concept of a DC-specific effect. Thus, we identified here a novel, non-redundant role of JAM-A in controlling DC motility, trafficking to lymph nodes, and activation of specific immunity.

Animals↗
PubMed2004

The long pentraxin PTX3 up-regulates tissue factor in activated monocytes: another link between inflammation and clotting activation.

Pentraxin-3 (PTX3), an acute-phase protein that belongs to the family of the PTXs, is found elevated in septic shock and increased in patients with acute myocardial infarction. As tissue factor (TF) plays a key role in thrombosis and inflammation associated with atherosclerosis and as we have recently reported that PTX3 increases TF synthesis in endothelial cells, we tested whether PTX3 could modulate TF expression in monocytes. Monocytes from peripheral blood of healthy donors were incubated with highly purified PTX3 with or without lipopolysaccharide (LPS). Cells were then disrupted, and procoagulant activity was assessed by a one-stage clotting time. PTX3 enhanced TF activity and antigen from LPS-stimulated monocytes in a dose-dependent way. The effect was specific, as other PTXs, such as C-reactive protein and serum amyloid P component, were ineffective. Moreover, the increase in activity was specific for LPS, as in the presence of other TF-inducing agents such as interleukin-1beta and tumor necrosis factor alpha, PTX3 was not effective. The increase in TF activity requires mRNA synthesis, as assessed by polymerase chain reaction. The mechanism by which PTX3 modulates TF synthesis resides in an enhanced IkappaB, alpha phosphorylation and degradation and increased migration of the transacting factor c-Rel/p65 into the nucleus, as determined by Western blot and electro-mobility shift assay. These results show that PTX3 is an enhancer of the expression of TF by mononuclear cells. In the area of vascular injury, during the inflammatory response, cell-mediated fibrin deposition takes place. PTX3 increases TF expression, thus potentially playing a role in thrombogenesis and wound healing.

Blood Coagulation↗
PubMed2004

Infiltration of tumours by macrophages and dendritic cells: tumour-associated macrophages as a paradigm for polarized M2 mononuclear phagocytes.

Macrophages and dendritic cells infiltrate tumours. In the tumour microenvironment, mononuclear phagocytes acquire properties of polarized M2 (or alternatively activated) macrophages. These functionally polarized cells, and similarly oriented or immature dendritic cells present in tumours, play a key role in subversion of adaptive immunity and in inflammatory circuits which promote tumour growth and progression.

Animals↗
PubMed2003

Acetaminophen down-regulates interleukin-1beta-induced nuclear factor-kappaB nuclear translocation in a human astrocytic cell line.

In previous studies performed to elucidate acetaminophen mechanism of action, we demonstrated that acetaminophen inhibits prostaglandin E2 production by interleukin (IL)-1beta-stimulated T98G human astrocytic cells, without affecting cyclooxygenase-2 enzymatic activity. As this result suggests an effect at transcriptional level, we examined whether the drug interferes with the activation of nuclear factor (NF)-kappaB and STAT3 transcription factors and with SAPK signal transducing factor. Western blot analysis of IkappaBalpha protein in the cytoplasm of IL-1beta-stimulated T98G cells and electrophoretic mobility shift assay (EMSA) on corresponding nuclear extracts indicate that acetaminophen (10-1000 microM) dose-dependently inhibits both IkappaBalpha degradation and NF-kappaB nuclear translocation. In the same cell type neither IL-1beta-dependent SAPK activation nor IL-6-induced STAT3 phosphorylation is affected by the drug. These data indicate that therapeutic concentrations of acetaminophen induce an inhibition of IL-1beta-dependent NF-kappaB nuclear translocation. The selectivity of this effect suggests the existence of an acetaminophen specific activity at transcriptional level that may be one of the mechanisms through which the drug exerts its pharmacological effects.

Acetaminophen↗
PubMed2003

Extracellular and intracellular decoys in the tuning of inflammatory cytokines and Toll-like receptors: the new entry TIR8/SIGIRR.

Following the identification of the interleukin (IL)-1 type II receptor as a prototypic decoy receptor, nonsignaling receptors with decoy functions have been identified for members of the IL-1/IL-18, tumor necrosis factor, IL-10, and IL-13 receptor families. Moreover, the silent receptor D6 is a promiscuous decoy and scavenger receptor of inflammatory chemokines. The type II IL-1 decoy receptor also acts as a dominant-negative molecule. Intracellular pathways of inhibition of IL-1 and Toll-like receptor (TLR) signaling have been identified. In particular, recent results suggest that the Toll/IL-1 receptor (TIR) family member TIR8, also known as single immunoglobulin IL-1-related receptor (SIGIRR), is a negative regulator of IL-1 and TLR signaling. Thus, extracellular and intracellular decoys tune the activation of members of the IL-1/TLR receptor family.

Animals↗
PubMed2003

Regulation of the chemokine receptor CXCR4 by hypoxia.

Cell adaptation to hypoxia (Hyp) requires activation of transcriptional programs that coordinate expression of genes involved in oxygen delivery (via angiogenesis) and metabolic adaptation (via glycolysis). Here, we describe that oxygen availability is a determinant parameter in the setting of chemotactic responsiveness to stromal-derived factor 1 (CXCL12). Low oxygen concentration induces high expression of the CXCL12 receptor, CXC receptor 4 (CXCR4), in different cell types (monocytes, monocyte-derived macrophages, tumor-associated macrophages, endothelial cells, and cancer cells), which is paralleled by increased chemotactic responsiveness to its specific ligand. CXCR4 induction by Hyp is dependent on both activation of the Hyp-inducible factor 1 alpha and transcript stabilization. In a relay multistep navigation process, the Hyp-Hyp-inducible factor 1 alpha-CXCR4 pathway may regulate trafficking in and out of hypoxic tissue microenvironments.

Animals↗
PubMed2003

Cross-linking of the mannose receptor on monocyte-derived dendritic cells activates an anti-inflammatory immunosuppressive program.

Immature monocyte-derived dendritic cells (DC) strongly express the endocytic mannose receptor (MR). Addition of a specific anti-MR mAb (clone PAM-1) for 24 h to cultures of immature DC induced phenotypical and functional maturation of the cells, assessed as up-regulation of costimulatory molecules and CD83, and chemotactic response to CCL19. A different isotype-matched anti-MR mAb (clone 19.2) had no significant effect. Engagement of MR with mAb PAM-1 induced the production of the anti-inflammatory cytokines IL-10, IL-1R antagonist, and of the nonsignaling IL-1R type II. In contrast IL-1beta, TNF, and IL-12 were not produced. PAM-1-treated DC were unable to polarize Th1 effector cells and did not secrete the chemokines CXCL10 and CCL19; in turn, they produced large amounts of CCL22 and CCL17, thus favoring the amplification of Th2 circuits. T cells cocultured with PAM-1-matured DC initially proliferated but later became anergic and behaved as suppressor/regulatory cells. Natural ligands binding to MR had differential effects. MUC III (a partially purified mucin), biglycan (a purified complex proteoglycan), and mannosylated lipoarabinomannan from Mycobacterium tuberculosis affected cytokine production with high IL-10, IL-1R antagonist, IL-1R type II, and inhibition of IL-12. In contrast, mannan, dextran, and thyroglobulin had no significant effect. In conclusion, the appropriate engagement of the MR by mAb PAM-1 and selected natural ligands elicit a secretory program in mono-derived DC characterized by a distinct profile of cytokines/chemokines with the ability to dampen inflammation and to inhibit the generation of Th1-polarized immune responses.

Antibodies, Monoclonal↗
PubMed2003

Specific recruitment of antigen-presenting cells by chemerin, a novel processed ligand from human inflammatory fluids.

Dendritic cells (DCs) and macrophages are professional antigen-presenting cells (APCs) that play key roles in both innate and adaptive immunity. ChemR23 is an orphan G protein-coupled receptor related to chemokine receptors, which is expressed specifically in these cell types. Here we present the characterization of chemerin, a novel chemoattractant protein, which acts through ChemR23 and is abundant in a diverse set of human inflammatory fluids. Chemerin is secreted as a precursor of low biological activity, which upon proteolytic cleavage of its COOH-terminal domain, is converted into a potent and highly specific agonist of ChemR23, the chemerin receptor. Activation of chemerin receptor results in intracellular calcium release, inhibition of cAMP accumulation, and phosphorylation of p42-p44 MAP kinases, through the Gi class of heterotrimeric G proteins. Chemerin is structurally and evolutionary related to the cathelicidin precursors (antibacterial peptides), cystatins (cysteine protease inhibitors), and kininogens. Chemerin was shown to promote calcium mobilization and chemotaxis of immature DCs and macrophages in a ChemR23-dependent manner. Therefore, chemerin appears as a potent chemoattractant protein of a novel class, which requires proteolytic activation and is specific for APCs.

Amino Acid Sequence↗
PubMed2003

Benzydamine inhibits monocyte migration and MAPK activation induced by chemotactic agonists.

1. The present study was aimed to investigate the effect of benzydamine, an anti-inflammatory drug devoid of activity on arachidonic acid metabolism, on monocyte chemotaxis and to define the possible biochemical correlates of activity. 2. Benzydamine inhibited monocyte chemotaxis in response to three classes of chemoattractants: the prototypic CC-chemokine CCL2 (MCP-1), the microbial product fMLP and the complement cascade component C5a. The effect was dose-dependent with IC50's of 100, 50 and 45 microm for MCP-1/CCL2, fMLP and C5a, respectively. At the dose of 100 microm, the effect resulted in a 50+/-10% inhibition of MCP-1/CCL2-induced chemotaxis and 53+/-6 and 54+/-5% inhibitions of chemotaxis in response of fMLP and C5a, respectively (n=3). 3. Receptor expression as well as calcium fluxes in response to chemoattractants were not affected by benzydamine. 4. Benzydamine strongly inhibited chemoattractant-induced activation of the mitogen-activated protein kinase (MAPK) ERK1/2, and of its upstream activator kinase MEK1/2. ERK1/12 activation in response to chemoattractants was 89-98% inhibited by a 100 microm concentration of benzydamine with an IC50 of 30 microm. 5. Under the same experimental conditions, pretreatment with 100 microm benzydamine caused a 75-89% inhibition of p38 activation (IC50 25 microm). 6. These results indicate that the anti-inflammatory activity of benzydamine is exerted at multiple levels, including monocyte migration to chemotactic factors associated to a blockage of ERK and p38 MAPK pathways.

Benzydamine↗
PubMed2003

IL-1 beta scavenging by the type II IL-1 decoy receptor in human neutrophils.

IL-1 elicits its cellular effects by binding a heterodimeric receptor consisting of IL-1RI and the accessory protein, IL-1RAcPr. In addition, it binds to IL-1RII, which lacking signaling function has been ascribed a decoy role. The fate of the ligand following interaction with the decoy receptor was examined in human polymorphonuclear cells (PMN), which express predominantly (>90%) IL-1RII. Incubation of PMN with IL-1beta results in a rapid decrease in cell surface-associated ligand accompanied by a concomitant increase in internalized IL-1 with 50-60% of IL-1beta located intracellularly within 1 h at 37 degrees C. The use of blocking Abs revealed that IL-1 internalization is mediated exclusively by the decoy receptor. The results of inhibitor analysis demonstrate that internalization requires ATP synthesis and involves clathrin-mediated endocytosis. Following removal of the ligand, the receptor was rapidly re-expressed on the cell surface. Cyclohexamide, a protein synthesis inhibitor, had no effect upon the process, suggesting that the re-expressed receptor was recycled. In addition, human keratinocytes stably transfected with IL-1RII (HaCAT 811) also internalized the IL-1RII with 43% cell surface receptor internalized after 90 min. Immunofluorescence microscopy revealed colocalization of the internalized receptor with wheat germ agglutinin-labeled internalized glycoproteins and early endosome Ag-1, a protein associated with the early endosome compartments, indicative of cellular uptake of IL-1RII by endocytosis. In contrast, little or no internalization was observed in other cells of immune origin. These results suggest that the decoy receptor IL-1RII can act as a scavenger of IL-1, representing a novel autoregulatory mechanism of the IL-1 system.

Arsenicals↗
PubMed2003

Pentraxin 3, a non-redundant soluble pattern recognition receptor involved in innate immunity.

Pentraxin 3 (PTX3) is the first long pentraxin identified. Long pentraxins consist of a C-terminal pentraxin domain, which has sequence similarity to C-reactive protein (CRP) and serum amyloid P (SAP) component (the classic short pentraxins), and of an unrelated N-terminal portion. PTX3 is made by diverse cell types, most prominently endothelial cells, macrophages and dendritic cells, in response to primary inflammatory signals (e.g. interleukin-1 (IL-1), tumour necrosis factor (TNF), lipopolysaccharide (LPS)). It binds diverse ligands, including microbial moieties, C1q and apoptotic cells. Evidence suggests that PTX3 plays a role in the regulation of innate resistance to pathogens, inflammatory reactions, possibly clearance of self-components and female fertility.

Animals↗
PubMed2003

The toll-like receptor repertoire of human B lymphocytes: inducible and selective expression of TLR9 and TLR10 in normal and transformed cells.

The present study was designed to investigate the expression of members of the toll-like receptor (TLR) family in human B cells. High-density, resting, and low-density activated tonsillar B cells expressed TLR9 and TLR10 mRNA transcripts at the highest levels. Expression was higher in activated B cells than in resting cells. Analysis of a range of resting and activated human leukocyte populations revealed that mRNA expression of TLR10 was restricted to B cells. Stimulation of resting B cells with anti-mu and anti-CD40 antibodies or with Staphylococcus aureus Cowan I bacteria (SAC) increased expression of TLR9 and TLR10. TLR1 and TLR4 expression were not significantly induced by B-cell activation. Interestingly, a CpG oligonucleotide, a TLR9 agonist, also stimulated TLR9 expression in B cells. Exposure to anti-mu antibodies augmented TLR9 expression, concomitantly and dramatically increasing the responsiveness of B cells to CpG oligonucleotides in terms of proliferation and chemokine (CC chemokine ligand 3 [CCL3] and CCL22) production. Epstein-Barr virus (EBV)-transformed cell lines and other cell lines representative of mature B-cell neoplasias (Burkitt lymphoma, follicular lymphoma, multiple myeloma) expressed TLR9 and/or TLR10, whereas pre-B cell lines were negative. These results show that normal and neoplastic human B lymphocytes express a distinct TLR repertoire including TLR9 and TLR10 and that expression is increased upon engagement of the antigen receptor complex or TLR9 itself. Regulated expression of selected TLRs in B cells is likely to play an important role in linking innate and adaptive immune responses in normal and pathologic conditions.

B-Lymphocytes↗
PubMed2003

Unique regulation of CCL18 production by maturing dendritic cells.

Dendritic cells (DC) orchestrate the trafficking of lymphocytes by secreting chemokines with different specificity and function. Chemokines are produced at higher levels by mature DC. This study shows that CCL18 is one of the most abundant chemokines produced by immature DC. In contrast to all other chemokines investigated to date, CCL18 was selectively down-regulated during the maturation process induced by LPS, TNF, CD40 ligand, Staphylococcus aureus Cowan I, Candida albicans, and influenza virus. IL-10 and vitamin D(3), two known inhibitors of DC differentiation and function, strongly promoted CCL18 secretion, whereas IFN-gamma, a costimulator of DC function, inhibited its production. IL-10 also induced CCL18 secretion in blood myeloid DC. No CCL18 secretion was observed in blood plasmacytoid DC. The opposite pattern of regulation was observed for CCL20, a prototypic inflammatory chemokine. CCL18 was found to be a chemotactic factor for immature DC. Therefore, CCL18 may act as a chemotactic signal that promotes the colocalization of immature DC with naive T lymphocytes in an IL-10-dominated environment with the consequent generation of T regulatory cells. These characteristics suggest that CCL18 may be part of an inhibitory pathway devoted to limiting the generation of specific immune responses at peripheral sites.

Cell Differentiation↗