Biomedical subjects

Federica M Marelli-Berg

Publications and source records attributed to Federica M Marelli-Berg.

13 recordsLinked to original sources

PubMed2007

Physiologic and aberrant regulation of memory T-cell trafficking by the costimulatory molecule CD28.

Productive T-cell immunity requires both the activation and the migration of specific T cells to the antigenic tissue. The costimulatory molecule CD28 plays an essential role in the initiation of T-cell-mediated immunity. We investigated the possibility that CD28 may also regulate migration of primed T cells to target tissue. In vitro, CD28-mediated signals enhanced T-cell transendothelial migration, integrin clustering, and integrin-mediated migration. In vivo, T cells bearing a mutation in the CD28 cytoplasmic domain, which abrogates PI3K activation, displayed normal clonal expansion but defective localization to antigenic sites following antigenic rechallenge. Importantly, antibody-mediated CD28 stimulation led to unregulated memory T-cell migration to extra-lymphoid tissue, which occurred independently of T-cell receptor (TCR)-derived signals and homing-receptor expression. Finally, we provide evidence that CD28- and CTLA-4-mediated signals exert opposite effects on T-cell trafficking in vivo. These findings highlight a novel physiologic function of CD28 that has crucial implications for the therapeutic manipulation of this and other costimulatory molecules.

Amino Acid Substitution↗

PubMed2005

Membrane phosphatidylserine distribution as a non-apoptotic signalling mechanism in lymphocytes.

Phosphatidylserine (PS) exposure is normally associated with apoptosis and the removal of dying cells. We observed that PS is exposed constitutively at high levels on T lymphocytes that express low levels of the transmembrane tyrosine phosphatase CD45RB. CD45 was shown to be a negative regulator of PS translocation in response to various signals, including activation of the ATP receptor P2X(7). Changes in PS distribution were shown to modulate several membrane activities: Ca(2+) and Na(+) uptake through the P2X(7) cation channel itself; P2X(7)-stimulated shedding of the homing receptor CD62L; and reversal of activity of the multidrug transporter P-glycoprotein. The data identify a role for PS distribution changes in signal transduction, rapidly modulating the activities of several membrane proteins. This seems to be an all-or-none effect, coordinating the activity of most or all the molecules of a target protein in each cell. The data also suggest a new approach to circumventing multidrug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2005

Tolerant T cells display impaired trafficking ability.

Based on our previous observation that anergic T lymphocytes lose their migratory ability in vitro, we have proposed that anergic T cells are retained in the site where they have been generated to exert their regulatory function. In this study we have analyzed T lymphocyte trafficking and motility following the induction of tolerance in vivo. In a model of non-deletional negative vaccination to xenoantigens in which dendritic cells (DC) localize to specific lymphoid sites depending on the route of administration, tolerant T cells remained localized in the lymph nodes colonized by tolerogenic DC, while primed T cells could traffic efficiently. Using an oral tolerance model that enables the 'tracking' of ovalbumin-specific TCR-transgenic T cells, we confirmed that T cells lose the ability to migrate through syngeneic endothelial cell monolayers following tolerance induction in vivo. Finally, we show that tolerant T cells (both in vitro and ex vivo) can inhibit migration of responsive T cells in an antigen-independent manner. Thus, hyporesponsive T cells localize at the site of tolerance induction in vivo, where they exert their anti-inflammatory properties. In physiological terms, this effect is likely to render immunoregulation a more efficient and controllable event.

Animals↗

PubMed2005

Transmigration through venular walls: a key regulator of leukocyte phenotype and function.

Leukocyte transmigration is a key event in host defense. As well as delivering leukocytes to sites of inflammation, this response also has an important role in immunity by regulating the responsiveness and behavior of leukocytes in the extravascular tissue. Recent evidence suggests that these events are associated with phenotypic and functional changes in migrating leukocytes mediated by signaling and transcriptional events triggered by the molecular interactions involved in leukocyte transendothelial cell migration. Transfer of membrane proteins from endothelial cells to migrating leukocytes and interaction of leukocytes with components of the perivascular basement membrane might also contribute to this effect. This Review will discuss the characteristics, potential mechanisms and the relevance of transmigration-induced change in leukocyte phenotype and responsiveness both within physiological and pathological scenarios.

Animals↗

PubMed2004

A novel pathway of alloantigen presentation by dendritic cells.

In the context of transplantation, dendritic cells (DCs) can sensitize alloreactive T cells via two pathways. The direct pathway is initiated by donor DCs presenting intact donor MHC molecules. The indirect pathway results from recipient DCs processing and presenting donor MHC as peptide. This simple dichotomy suggests that T cells with direct and indirect allospecificity cannot cross-regulate each other because distinct APCs are involved. In this study we describe a third, semidirect pathway of MHC alloantigen presentation by DCs that challenges this conclusion. Mouse DCs, when cocultured with allogeneic DCs or endothelial cells, acquired substantial levels of class I and class II MHC:peptide complexes in a temperature- and energy-dependent manner. Most importantly, DCs acquired allogeneic MHC in vivo upon migration to regional lymph nodes. The acquired MHC molecules were detected by Ab staining and induced proliferation of Ag-specific T cells in vitro. These data suggest that recipient DCs, due to acquisition of donor MHC molecules, may link T cells with direct and indirect allospecificity.

Adenosine Triphosphate↗

PubMed2004

IFN-alpha subtypes differentially affect human T cell motility.

The type I IFN family includes 14 closely related antiviral cytokines that are produced in response to viral infections. They bind to a common receptor, and have qualitatively similar biological activities. The physiological relevance of this redundancy is still unclear. In this study, we analyzed and compared the effects of two potent antiviral type I IFNs, IFN-alpha 2 and IFN-alpha 8, on the motility of various populations of human T lymphocytes in vitro. In this study, we show that IFN-alpha 2 induces chemokinesis of both CD4(+) and CD8(+) T cells at various stages of differentiation, and induces functional changes that result in enhanced T cell motility, including up-regulation of the integrins LFA-1 and VLA-4, and subsequently, increased ICAM-1- and fibronectin-dependent migration. In contrast, IFN-alpha 8 did not affect T cell motility, despite having similar antiviral properties and similar effects on the induction of the antiviral protein MxA. However, transcription of other IFN-stimulated genes showed that transcription of these genes is selectively activated by IFN-alpha 2, but not IFN-alpha 8, in T cells. Finally, while the antiviral activity of the two subtypes is inhibited by Abs against the two subunits of the IFN-alpha receptor, the chemokinetic effect of IFN-alpha 2 is selectively blocked by Abs against the A1 receptor subunit. These observations are consistent with the possibility that subtype-specific intracellular signaling pathways are activated by type I IFNs in T lymphocytes.

Antibodies, Monoclonal↗

PubMed2004

Beta-adrenergic stimulation induces interleukin-18 expression via beta2-AR, PI3K, Akt, IKK, and NF-kappaB.

We investigated whether beta-adrenergic receptor (beta-AR) stimulation induces the expression of interleukin (IL)-18, a proinflammatory cytokine, in myocardium and in cardiac-derived endothelial cells (CDEC) via activation of nuclear factor (NF)-kappaB. Our results indicate that isoproterenol (ISO) activates NF-kappaB DNA binding activity, and induces myocardial and systemic elaboration of IL-18 via beta2-AR signaling. Furthermore, in CDEC, ISO increased basal and inducible promoter activities, increased IL-18 gene transcription and mRNA stability, and induced IL-18 expression via beta2-AR agonism. Signaling required GiPI3K, PI3K, Akt, IKK, and NF-kappaB. In conclusion, our results indicate for the first time that isoproterenol induces myocardial and systemic elaboration of IL-18 via a beta2-AR and NF-kappaB-dependent mechanism. Similar events may occur in heart failure, a disease state characterized by sustained beta-AR activation.

Adrenergic beta-Agonists↗

PubMed2004

Antigen presentation by the endothelium: a green light for antigen-specific T cell trafficking?

The functional consequences of recognition of antigen displayed by the endothelium during T cell extravasation in the development of an immune response have been a matter of debate for a long time. Most investigations have focused on the induction of proliferative responses and cytokine production by T cells. In parallel, endothelial cells have been shown to express costimulatory molecules with positive and negative regulatory effects on T cell responses. Recent studies have provided an alternative view of the antigen presenting cell function of endothelial cells, suggesting that cognate recognition of the endothelium by trafficking T cells is a key event in selecting the migration of antigen-specific lymphocytes into the site of inflammation.

Animals↗

PubMed2003

Cognate recognition of the endothelium induces HY-specific CD8+ T-lymphocyte transendothelial migration (diapedesis) in vivo.

The physiologic significance of MHC-peptide complex presentation by endothelial cells (ECs) to trafficking T lymphocytes remains unresolved. On the basis of our observation that cognate recognition of ECs enhanced transendothelial migration of antigen-specific T lymphocytes in vitro, we have proposed that by displaying antigenic peptides from the underlying tissue, ECs promote the recruitment of antigen-specific T cells. In this study, we have tested this hypothesis by comparing the trafficking of HY-specific T lymphocytes into antigenic and nonantigenic tissue using in vivo models of T-cell recruitment. Up-regulated expression of H2 molecules presenting endogenous antigen in the peritoneal mesothelium and vessels led to the local recruitment of HY-specific T cells in male, but not female, mice. Intravital microscopy experiments analyzing EC-HY-specific T-cell interactions in the cremasteric vascular bed revealed that cognate recognition of the endothelium results in enhanced diapedesis of T cells into the tissue, while not affecting rolling and adhesion. Our results are consistent with the hypothesis that, under inflammatory conditions, antigen presentation by the endothelium contributes to the development and specificity of T-cell-mediated inflammation by favoring the selective migration of antigen-specific T cells.

Animals↗

PubMed2003

Anergic T cells exert antigen-independent inhibition of cell-cell interactions via chemokine metabolism.

Due to their ability to inhibit antigen-induced T-cell activation in vitro and in vivo, anergic T cells can be considered part of the spectrum of immunoregulatory T lymphocytes. Here we report that both murine and human anergic T cells can impair the ability of parenchymal cells (including endothelial and epithelial cells) to establish cell-cell interactions necessary to sustain leukocyte migration in vitro and tissue infiltration in vivo. The inhibition is reversible and cell-contact dependent but does not require cognate recognition of the parenchymal cells to occur. Instrumental to this effect is the increased cell surface expression and enzymatic activity of molecules such as CD26 (dipeptidyl-peptidase IV), which may act by metabolizing chemoattractants bound to the endothelial/epithelial cell surface. These results describe a previously unknown antigen-independent anti-inflammatory activity by locally generated anergic T cells and define a novel mechanism for the long-known immunoregulatory properties of these cells.

Animals↗

PubMed2002

Chemokine-cytokine cross-talk. The ELR+ CXC chemokine LIX (CXCL5) amplifies a proinflammatory cytokine response via a phosphatidylinositol 3-kinase-NF-kappa B pathway.

It is well established that cytokines can induce the production of chemokines, but the role of chemokines in the regulation of cytokine expression has not been fully investigated. Exposure of rat cardiac-derived endothelial cells (CDEC) to lipopolysaccharide-induced CXC chemokine (LIX), and to a lesser extent to KC and MIP-2, activated NF-kappaB and induced kappaB-driven promoter activity. LIX did not activate Oct-1. LIX-induced interleukin-1beta and tumor necrosis factor-alpha promoter activity, and up-regulated mRNA expression. Increased transcription and mRNA stability both contributed to cytokine expression. LIX-mediated cytokine gene transcription was inhibited by interleukin-10. Transient overexpression of kinase-deficient NF-kappaB-inducing kinase (NIK) and IkappaB kinase (IKK), and dominant negative IkappaB significantly inhibited LIX-mediated NF-kappaB activation in rat CDEC. Inhibition of G(i) protein-coupled signal transduction, poly(ADP-ribose) polymerase, phosphatidylinositol 3-kinase, and the 26 S proteasome significantly inhibited LIX-mediated NF-kappaB activation and cytokine gene transcription. Blocking CXCR2 attenuated LIX-mediated kappaB activation and kappaB-driven promoter activity in rat CDEC that express both CXCR1 and -2, and abrogated its activation in mouse CDEC that express only CXCR2. These results indicate that LIX activates NF-kappaB and induces kappaB-responsive proinflammatory cytokines via either CXCR1 or CXCR2, and involved phosphatidylinositol 3-kinase, NIK, IKK, and IkappaB. Thus, in addition to attracting and activating neutrophils, the ELR(+) CXC chemokines amplify the inflammatory cascade, stimulating local production of cytokines that have negative inotropic and proapoptotic effects.

Animals↗

PubMed2002

Functional consequences of noncognate interactions between CD4+ memory T lymphocytes and the endothelium.

The recruitment of Ag-specific T cells to sites of inflammation is a crucial step in immune surveillance. Although the molecular interactions controlling T cell extravasation are relatively well characterized, the effects of these events on T cell function are still poorly understood. Using an in vitro model of transendothelial migration of human CD4(+) memory T cells, we have investigated the molecular and functional changes induced in T cells that come into contact with the endothelium. First, we show that transendothelial migration is precluded by signals that lead to T cell division. In addition, activation of the transcription factor AP-1, without induction of NF-kappaB, is observed in T cells after noncognate interactions with endothelial cells (EC), a pattern of transcriptional regulation different from that observed in dividing T cells. Up-regulation of certain adhesion (CD11a, CD49d), activation (CD69), and costimulatory (CD86) receptors accompany these transcriptional events. Most importantly, recently migrated T cells display a faster rate of migration when reseeded onto an EC monolayer. Finally, T cells become hyperresponsive to antigenic challenge after noncognate interactions with the endothelium. These effects appear not to be due to the selection of preactivated T lymphocytes, because they occur also in clonal T cell populations and appear to be mediated by alpha(L)beta(2) integrin-CD54 interactions. We conclude that CD4(+) memory T cell extravasation is accompanied by phenotypic and functional changes induced by the interactions with the EC, which favor tissue infiltration by T cells and their further activation once they reach the antigenic site.

Antigens↗

PubMed2002

Conditional immortalization of growth factor-responsive cardiac endothelial cells from H-2K(b)-tsA58 mice.

Although mouse endothelial cells (EC) may advance our understanding of endothelial function, primary EC remain difficult to isolate. We have established a murine cardiac endothelial cell line (MCEC-1) from transgenic mice harboring a temperature-sensitive simian virus 40 large TAg gene (tsA58 TAg) under H-2K(b) class I promoter control. MCEC-1 cells were characterized by their ability to form tubes, Griffonia simplicifolia isolectin B4 binding, and CD31, intercellular adhesion molecule (ICAM)-2, and endoglin expression. MCEC-1 cells proliferated rapidly under permissive conditions [33 degrees C with interferon (IFN)-gamma], where the T antigen is active and transcription is activated by the presence of IFN-gamma, whereas under nonpermissive conditions (38 degrees C without IFN-gamma) proliferation was reduced by 30-fold and the EC showed enhanced proliferation in response to growth factors. Expression of E- and P-selectin, ICAM-1, and vascular cell adhesion molecule-1 was upregulated by tumor necrosis factor-alpha and interleukin-1 beta, and MCEC-1 cells, in contrast to primary EC, were amenable to transfection by lipofection. This novel line will allow further study of the role of the endothelium in cardiovascular disease. Moreover, this technique will allow EC to be readily obtained from genetically modified mice backcrossed with H-2K(b)-tsA58 mice.

Animals↗