Showing papers by "Silvano Sozzani published in 1998"

Differential Expression of Chemokine Receptors and Chemotactic Responsiveness of Type 1 T Helper Cells (Th1s) and Th2s

Abstract: T helper cells type 1 (Th1s) that produce interferon-γ predominantly mediate cellular immune responses and are involved in the development of chronic inflammatory conditions, whereas Th2s which produce large amounts of IL-4 and IL-5 upregulate IgE production and are prominent in the pathogenesis of allergic diseases. The precise factors determining whether Th1- or Th2-mediated immune responses preferentially occur at a peripheral site of antigen exposure are largely unknown. Chemokines, a superfamily of polypeptide mediators, are a key component of the leukocyte recruitment process. Here we report that among four CXC (CXCR1-4) and five CC (CCR1-5) chemokine receptors analyzed, CXCR3 and CCR5 are preferentially expressed in human Th1s. In contrast, Th2s preferentially express CCR4 and, to a lesser extent, CCR3. In agreement with the differential chemokine receptor expression, Th1s and Th2s selectively migrate in response to the corresponding chemokines. The differential expression of chemokine receptors may dictate, to a large extent, the migration and tissue homing of Th1s and Th2s. It may also determine different susceptibility of Th1s and Th2s to human immunodeficiency virus strains using different fusion coreceptors.

Differential regulation of chemokine receptors during dendritic cell maturation: a model for their trafficking properties.

Abstract: Upon exposure to immune or inflammatory stimuli, dendritic cells (DC) migrate from peripheral tissues to lymphoid organs, where they present Ag CC chemokines induce chemotactic and transendothelial migration of immature DC, in vitro Maturation of DC by CD40L, or by LPS, IL-1, and TNF, induces down-regulation of the two main CC chemokine receptors expressed by these cells, CCR1 and CCRS, and abrogates chemotaxis to their ligands Inhibition was rapid (<1 h) and included the unrelated agent FMLP Concomitantly, the expression of CCR7 and the migration to its ligand EBI1 ligand chemokine (ELC)/macrophage inflammatory protein (MIP)-3beta, a chemokine expressed in lymphoid organs, were strongly up-regulated, though with slower kinetics (24-48 h) Rapid inhibition of responsiveness to chemoattractants present at sites of inflammation and immune reaction may be permissive for leaving peripheral tissues Conversely, the slower acquisition of responsiveness to ELC/MIP-3beta may guide subsequent localization of DC in lymphoid organs

Selective up-regulation of chemokine receptors CCR4 and CCR8 upon activation of polarized human type 2 Th cells

Abstract: Polarized Th1 and Th2 cells differentially express adhesion molecules and chemokine receptors, endowing these cells with distinct tissue homing capabilities. Here we report that, in contrast to other chemokine receptors, the expression of CCR4 and CCR8 on Th2 cells is transiently increased following TCR and CD28 engagement. IL-4 is not required for this activation-induced up-regulation of CCR4 and CCR8. In accordance with receptor expression, the response of Th2 cells to I-309 (CCR8 ligand) and thymus- and activation-regulated chemokine (CCR4 and CCR8 ligand) is enhanced upon activation. Moreover, activated Th1 cells up-regulate CCR4 expression and functional responsiveness to thymus- and activation-regulated chemokine. Analysis of polarized subsets of CD8+ T cells reveals a similar pattern of chemokine receptor expression and modulation of responsiveness. Taken together, these findings suggest that an up-regulation of CCR4 and CCR8 following Ag encounter may contribute to the proper positioning of activated T cells within sites of antigenic challenge and/or specialized areas of lymphoid tissues.

Elevated cerebrospinal fluid levels of monocyte chemotactic protein-1 correlate with HIV-1 encephalitis and local viral replication.

Abstract: OBJECTIVE To investigate whether the CC-chemokine monocyte chemotactic protein (MCP)-1 could play a role in the pathogenesis of HIV infection of the central nervous system. This hypothesis was suggested by previous observations, including our finding of elevated cerebrospinal fluid (CSF) levels of this chemokine in patients with cytomegalovirus (CMV) encephalitis. DESIGN AND METHODS CSF levels of MCP-1 were determined in 37 HIV-infected patients with neurological symptoms, and were compared with both the presence and severity of HIV-1 encephalitis at post-mortem examination and CSF HIV RNA levels. MCP-1 production by monocyte-derived macrophages was tested after in vitro infection of these cells by HIV. RESULTS CSF MCP-1 levels were significantly higher in patients with (median, 4.99 ng/ml) than in those without (median, 1.72 ng/ml) HIV encephalitis. Elevated CSF MCP-1 concentrations were also found in patients with CMV encephalitis and with concomitant HIV and CMV encephalitis (median, 3.14 and 4.23 ng/ml, respectively). HIV encephalitis was strongly associated with high CSF MCP-1 levels (P = 0.002), which were also correlated to high HIV-1 RNA levels in the CSF (P = 0.007), but not to plasma viraemia. In vitro, productive HIV-1 infection of monocyte-derived macrophages upregulated the secretion of MCP-1. CONCLUSIONS Taken together, these in vivo and in vitro findings support a model whereby HIV encephalitis is sustained by virus replication in microglial cells, a process amplified by recruitment of mononuclear cells via HIV-induced MCP-1.

Interleukin 10 Increases CCR5 Expression and HIV Infection in Human Monocytes

Abstract: The immunosuppressive and antiinflammatory cytokine interleukin (IL) 10 selectively upregulates the expression of the CC chemokine receptors CCR5, 2, and 1 in human monocytes by prolonging their mRNA half-life. IL-10–stimulated monocytes display an increased number of cell surface receptors for, and better chemotactic responsiveness to, relevant agonists than do control cells. In addition, IL-10–stimulated monocytes are more efficiently infected by HIV BaL. This effect was associated to the enhancement of viral entry through CCR5. These data add support to an emerging paradigm in which pro- and antiinflammatory molecules exert reciprocal and opposing influence on chemokine agonist production and receptor expression.

Monocytes from Wiskott-Aldrich patients display reduced chemotaxis and lack of cell polarization in response to monocyte chemoattractant protein-1 and formyl-methionyl-leucyl-phenylalanine.

Abstract: Wiskott-Aldrich syndrome (WAS) is an X-linked disorder characterized by trombocytopenia, eczema, and progressive decline of the immune function. In addition, lymphocytes and platelets from WAS patients have morphologic abnormalities. Since chemokines may induce morphologic changes and migration of leukocytes, we investigated the monocyte response to chemoattractants in cells from WAS patients with an identified mutation in the WAS protein gene. Here, we report that monocytes derived from four patients with molecularly defined typical WAS have a severely impaired migration in response to FMLP and to the chemokines monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1alpha compared with normal donors. Conversely, neither MCP-1 binding to monocytes nor induction of the respiratory burst by MCP-1 and FMLP is significantly different between WAS patients and normal donors. Within a few minutes of stimulation, monocytes respond to chemokines with increased expression of adhesion molecules and with morphologic changes such as cell polarization. Although up-regulation of CD11b/CD18 expression following stimulation with FMLP or MCP-1 is preserved in WAS patients, cell polarization is dramatically decreased. Staining of F-actin by FITC-phalloidin in monocytes stimulated with chemoattractants shows F-actin to have a rounded shape in WAS patients, as opposed to the polymorphic distribution of F-actin in the polarized monocytes from healthy donors. These results suggest that WAS protein is involved in the monocyte response to the chemokines MCP-1 and macrophage inflammatory protein-1alpha.

Selective inhibition of expression of the chemokine receptor CCR2 in human monocytes by IFN-gamma

Abstract: IFN-gamma is a potent activator of mononuclear phagocyte function and promotes the development of Th1 responses Moreover, it induces and modulates chemokine production in a variety of cell types, including mononuclear phagocytes In the present study, we examined the effect of IFN-gamma on the expression of CC chemokine receptors in human monocytes IFN-gamma selectively and rapidly inhibited expression of the monocyte chemotactic protein (MCP) receptor CCR2 with an ED50 of approximately 50 U/ml The effect was rapid (detectable after 1 h) and reversible Other chemokine receptors (CCR1, CCR3, CCR4, and CCR5) were not substantially affected, and CXCR4 was reduced IFN-gamma acted in concert with LPS, TNF-alpha, and IL-1beta in inhibiting CCR2 expression IFN-gamma-treated monocytes showed a shorter half-life of CCR2 mRNA compared with untreated cells, whereas the rate of nuclear transcription was unaffected The inhibition of CCR2 mRNA expression by IFN-gamma was associated with a lower number of surface receptors and lower chemotactic responsiveness Thus, IFN-gamma, an inducer of MCP-1 and MCP-3 in mononuclear phagocytes, selectively inhibits expression of the MCP receptor CCR2 in monocytes These results are consistent with an emerging paradigm of divergent regulation by several agents of chemokine production and receptor expression in monocytes The inhibition of MCP-1R expression may serve as a means of retaining mononuclear phagocytes at sites of inflammation and as a feedback mechanism in the regulation of recruitment from the blood

Reduced Tumorigenicity and Augmented Leukocyte Infiltration After Monocyte Chemotactic Protein-3 (MCP-3) Gene Transfer: Perivascular Accumulation of Dendritic Cells in Peritumoral Tissue and Neutrophil Recruitment Within the Tumor

Abstract: Monocyte chemotactic protein-3 (MCP-3) is a C-C chemokine that interacts with the CCR1, CCR2, and CCR3 receptors and has a spectrum of action encompassing T cells, NK cells, eosinophils, and dendritic cells (DC), in addition to mononuclear phagocytes. This broad spectrum of action prompted the present study aimed at assessing the antitumor activity of MCP-3 in a gene transfer approach and at providing information as to the actual in vivo leukocyte recruiting capacity of MCP-3. P815 mastocytoma cells transfected with the gene coding MCP-3 (P815/ MCP-3 ) grew in syngeneic hosts and underwent rejection. Rejection was associated with profound alterations of leukocyte infiltration and resistance to subsequent challenge with P815 cells. Tumor-associated macrophages, already present in copious numbers, T cells, eosinophils, and neutrophils, increased in tumor tissues after gene transfer. DC, identified as DEC205 + , high MHC class II + , CD11c + cells, did not increase substantially in the tumor mass. However, in peritumoral tissues, DC accumulated in perivascular areas. P815/ MCP-3 -transfected tumor cells grew normally in nude mice. Increased accumulation of macrophages and polymorphonuclear neutrophils was evident also in nude mice. mAb against CD4, CD8, and IFN-γ, but not against IL-4, inhibited rejection of MCP-3- producing cells. An anti-polymorphonuclear mAb caused only a retardation of MCP-3-elicited tumor rejection. Thus, MCP-3 gene transfer elicits tumor rejection by activating type I T cell-dependent immunity. It is tempting to speculate that altered trafficking of APCs, which express receptors and respond to MCP-3, together with recruitment of activated T cells, underlies activation of specific immunity by MCP-3- transfected cells.

Identification of the CC chemokines TARC and macrophage inflammatory protein-1β as novel functional ligands for the CCR8 receptor

Abstract: Section of Pathology and Immunology, Department of Biotechnology, University of Brescia,Brescia, ItalyChemokines are key molecules in directing leukocyte migration toward sites of inflamma-tion. We have previously cloned a putative CC chemokine receptor gene, TER1, whoseexpression is restricted to lymphoid tissues and cell lines. Recently, this receptor has beenshown to signal in response to the human CC chemokine I-309 and thus it has beenrenamed CCR8 according to the current nomenclature. In the present study, we report theidentification of the CC chemokines thymus and activation-regulated cytokine (TARC) andmacrophage inflammatory protein-1 ‚ (MIP-1 ‚) as CCR8 ligands, as they induce chemotaxisin CCR8 Jurkat stable transfectants. Furthermore, we have generated a polyclonal antise-rum that is able to recognize the CCR8 molecule in transfectant lysates. The pattern of CCR8mRNA expression and the functional effects exerted by its ligand suggest that the triggeringof this receptor may regulate multiple functions including activation, migration and prolifera-tion of lymphoid cells.

In Vitro Generation of Human Cytomegalovirus pp65 Antigenemia, Viremia, and LeukoDNAemia

Abstract: Immunocompromised patients with disseminated human cytomegalovirus (HCMV) infection have circulating PMN carrying HCMV pp65 (antigenemia), infectious virus (viremia), and viral DNA (leukoDNAemia). Because HCMV does not fully replicate in PMN, it is generally hypothesized that virions and viral materials are taken up by phagocytosis from fully permissive HCMV-infected endothelial cells. However, no experimental evidence has ever been provided for these PMN-endothelium interactions. PMN from 11 donors were cocultured with endothelial cells infected with an endothelium-adapted HCMV strain and with human fibroblasts infected with low-passaged clinical and laboratory-adapted HCMV strains. pp65-positive PMN were detected after coculture with both HCMV-infected endothelial and fibroblast cells, provided that wild and not laboratory-adapted strains were used. In addition, cocultured PMN carried infectious virus as demonstrated by virus isolation and presence of complete virus particles by electron microscopy. Moreover, high levels of viral DNA were consistently detected by quantitative PCR in cocultured PMN. Thus, we have generated in vitro the three most important viral parameters detected in patients with disseminated HCMV infection (antigenemia, viremia, and leukoDNAemia). The failure of laboratory-adapted HCMV strain to induce this phenomenon demonstrates that important modifications have occurred in attenuated viral strains affecting basic biological functions.

Chemokines and chemokine receptors during activation and deactivation of monocytes and dendritic cells and in amplification of th1 versus th2 responses

Abstract: Chemokines are a superfamily of small cytokines which are generally chemotactic for leukocytes. The general features of chemokines and their receptors are reviewed. Recent evidence indicates that receptor expression dictates the spectrum of action of chemokines, as shown recently for Th1 and Th2 cells. Chemokines represent amplification loops of polarized Th1 and Th2 responses. Receptor expression is tightly regulated during differentiation, activation, and deactivation of mononuclear phagocytes and dendritic cells. Thus, regulation of receptor expression is crucial as a set point of the chemokine system.

Purification and identification of chemokines potentially involved in kidney-specific metastasis by a murine lymphoma variant: Induction of migration and NFκB activation

Abstract: The ESb-MP cell line is the subclone of a highly malignant variant of murine methylcholanthrene-induced T lymphoma, ESb. When injected in vivo, ESb-MP cells metastasize to the kidney with high frequency, whereas a non-adherent variant, ESb cells, rarely form metastatic foci in the kidney. Our previous results showed that ESb-MP, but not ESb, cells were able to migrate in response to murine kidney-conditioned media (KCM). In an effort to characterize the tumor cell chemoattractant(s) produced by kidney cells, we found that the murine kidney mesangial cell line MES-13 released more chemotactic activity for ESb-MP cells than present in KCM. A major heparin-binding chemotactic activity was purified to homogeneity by sequential fast-performance liquid chromatography and reversed phase high-performance liquid chromatography. Amino acid sequencing of the formic acid-digested active fractions revealed that the purified protein was identical to murine MCP-1(JE) and its activity was neutralized by an anti-MCP-1(JE) antibody. Another chemokine, RANTES, was also purified from MES-13 cell supernatant. The chemotactic activity contained in the MES-13 cell supernatant and in murine KCM was neutralized in part by a combination of anti-MCP-1(JE) and anti-RANTES antibodies. We further examined the differences in the ESb-MP and ESb cells. Binding studies using a variety of radio-iodinated chemokines showed that although both ESb-MP and ESb cells expressed substantial levels of high-affinity binding sites for CC chemokines, only ESb-MP cells migrated in response to CC chemokines and these cells constitutively expressed higher levels of β2 integrin adhesion protein CD11b than their parental ESb cells. CC chemokines also activated NFκB in ESb-MP but not in ESb cells. Our results indicate that CC chemokines selectively chemoattract and activate ESb-MP cells. Thus, locally produced chemokines, MCP-1(JE) and RANTES in particular, may contribute to the preferential metastasis of ESb-MP cells to the kidneys. Int. J. Cancer75:900–907, 1998. Published 1998 Wiley-Liss, Inc.

Interleukin-1beta and interferon-gamma differentially regulate release of monocyte chemotactic protein-1 and interleukin-8 by human bronchial epithelial cells.

Abstract: Airway inflammation is characterized by an accumulation of activated leukocytes. Bronchial epithelial cells may contribute to this process by releasing chemokines and by expressing surface membrane molecules involved in the adhesion and activation of the recruited leukocytes. In this study, we analyzed the effects of cytokines and glucocorticoids on the release of monocyte chemotactic protein-1 (MCP-1), a potent chemoattractant for predominantly monocytes and lymphocytes, by human bronchial epithelial cells and compared this with the release of interleukin-8 (IL-8), which potently attracts neutrophils. In addition, we analyzed the effects of cytokines and glucocorticoids on the epithelial expression of intercellular adhesion molecule (ICAM)-1, CD40, and human leukocyte antigen (HLA) class II molecules. Primary cultures of human bronchial epithelial cells constitutively released MCP-1 and IL-8. IFN-gamma greatly increased MCP-1 release, which was accompanied by increased expression of MCP-1 mRNA and an increased monocyte chemotactic potential. In contrast, IFN-gamma had no effect on the release of IL-8, but it did increase the epithelial expression of ICAM-1, CD40, and HLA class II molecules. IL-1beta increased both MCP-1 and IL-8 release, and increased the expression of ICAM-1 and CD40, but not HLA class II molecules. Dexamethasone partially inhibited the cytokine-induced release of MCP-1 and IL-8 and the expression of ICAM-1, CD40, and HLA class II molecules by human bronchial epithelial cells. Our results indicate that IFN-gamma and IL-1beta differentially regulate the MCP-1 and IL-8 release by human bronchial epithelial cells. In addition, IL-1beta and particularly IFN-gamma increase the expression of ICAM-1, HLA class II and/or CD40 molecules, which are involved in the adhesion and possibly activation of the recruited leukocytes. Finally, the beneficial effect of glucocorticoid therapy in airway inflammatory diseases may be mediated in part by inhibition of chemokine release and ICAM-1, CD40, and HLA class II expression by bronchial epithelial cells.

Old and new chemokines. Pharmacological regulation of chemokine production and receptor expression: mini-review.

Abstract: Chemokines are a superfamily of proteins that play a crucial role in immune and inflammatory reactions and in viral infections 1,2. Chemokines can be grouped in two main subfamilies defined CXC (or α) and CC (or β) according to the spacing of the first two cysteine residues. Recently, the new chemokines lymphotactin and fractalkine have been reported and define two additional classes of the chemokine superfamily 1,2. CXC chemokines, of which IL-8 is the prototype, are mainly active on neutrophils and T lymphocytes. CC chemokines have a wider spectrum of action, being active on monocytes, granulocytes, T and B lymphocytes, and natural killer (NK) cells 1,2. Lymphotactin, the only C chemokine so far described, is active on T lymphocytes and NK cells. Inflammatory cytokines (e.g. IL-1, tumor necrosis factor (TNF) and IL-6) and bacterial products are potent inducers of chemokine production both in vitro and in vivo. On the contrary, molecules with immunosuppressive and anti-inflammatory activity, such as IL-10 and glucocorticoid hormones, inhibit chemokine production. Chemokines bind to and activate seventransmembrane domain receptors. Five receptors for the CXC chemokines, named CXCR1 to 5, and eight for CC chemokines (CCR1 to 8) have been cloned and characterized in leukocyte populations. Recently, the receptor for fractalkine (CX3CR1) has been cloned while the lymphotactin receptor is still unknown. With only a few exceptions, chemokine receptors bind multiple chemokines and recently it was shown that some of them can function as entry/fusion co-factors for HIV-1 infection 1,2. Emerging evidence indicates that chemokine receptors can be modulated by inflammatory and anti-inflammatory signals. The pattern of expression of chemokine receptors is the major factor that dictates the selectivity of chemokines for different target cells, and regulation of the expression of chemokine receptors may be crucial as a set point for chemokine action. Here, we report the characterization of dendritic cells (DC) as a new important target for chemokine action. In addition, we show that proinflammatory agonists (e.g. LPS) and immunosuppressive and anti-inflammatory cytokines, such as IL-10, are able to selectively modulate the expression of CC chemokine receptors in human mononuclear phagocytes. These results are consistent with a novel paradigm of opposite regulation of chemokines and their receptors by proand anti-inflammatory signals.

Chemokines: Attraction of dendritic cells and role in tumor immunobiology

Abstract: In this chapter we will discuss selected aspects of the structure and function of chemokines, with emphasis on monocyte chemotactic proteins (MCPs) as prototypic CC chemokine. Among functions, we will emphasize recent results on molecules which attract dendritic cells of obvious relevance for skin immunobiology and emphasize potential relevance for tumor therapy.

Regulation of Inflammatory Cytokine Receptor Expression by Pro- and Anti-Inflammatory Molecules

Abstract: Publisher Summary Inflammatory cytokines act in cascades. One can recognize schematically primary inflammatory cytokines, the prototype of which is IL-1, and secondary effector molecules, among which chemokines play an important role in recruitment. Pro- and anti-inflammatory signals regulate the production of primary and secondary inflammatory cytokines, sometimes in unexpected ways. Primary and secondary inflammatory cytokines are highly regulated by diverse signals. Emphasis has largely been on how pro- and anti-inflammatory molecules affect cytokine production. The possibility that micro environmental signals regulate the action of pro-inflammatory cytokines by acting at the receptor level has been less extensively studied.

Molecules Involved in the Recruitment and Regulation of Tumor-Associated Macrophages

Abstract: Recirculation and accumulation of leukocytes in tissues are crucial aspects of physiological processes. However, selective accumulation of one or more leukocyte subpopulations is the hallmark of pathological conditions including allergic and inflammatory reactions and tumors.