Enhanced expression of eotaxin and CCR3 in atopic dermatitis.
(49/1708)
Chemokines are thought to play an important part in the development of inflammation in atopic dermatitis. Eotaxin, a CC chemokine, is a potent chemoattractant and activator of human eosinophils, basophils and Th2 lymphocytes which acts via the chemokine receptor CCR3. We studied the expression of eotaxin and CCR3, as well as MCP-3, MIP-1alpha and interleukin-8, in atopic dermatitis and normal skin by immunohistochemistry and nested reverse transcriptase-polymerase chain reaction. Skin biopsy specimens were obtained from nonlesional and lesional skin of patients with atopic dermatitis and of nonatopic controls. Immunoreactivity and transcripts of eotaxin and CCR3 were significantly increased in lesional skin from atopic dermatitis, but not in nonatopic controls. In nonlesional atopic dermatitis samples CCR3 expression was also significantly increased at the mRNA and protein level, whereas eotaxin was increased at the mRNA level only. No significant difference in the expression of MCP-3, MIP-1alpha, and interleukin-8 was observed between skin samples from atopic dermatitis and nonatopic controls. The enhanced local production of eotaxin may lead to the recruitment of eosinophils and T lymphocytes, which both express CCR3 and contribute to the initiation and maintenance of inflammation. (+info)
HHV8-encoded vMIP-I selectively engages chemokine receptor CCR8. Agonist and antagonist profiles of viral chemokines.
(50/1708)
Uncertainty regarding viral chemokine function is mirrored by an incomplete knowledge of host chemokine receptor usage by the virally encoded proteins. One such molecule is vMIP-I, a C-C type chemokine of undefined function and binding specificity, encoded by the Kaposi's sarcoma herpesvirus HHV-8. We report here that vMIP-I binds to and induces cytosolic [Ca(2+)] signals in human T cells selectively through CCR8, a CC chemokine receptor associated with Th2 lymphocytes. Furthermore, using a panel of 65 different human, viral, and rodent chemokines, we have established a comprehensive ligand binding "fingerprint" for CCR8. The receptor exhibits marked "high" affinity (K(d) < 15 nM) only for four chemokines, three of them of viral origin: vMIP-I, vMIP-II, vMCC-I, and human I-309. A previously unreported second class of lower affinity ligands includes MCP-3 and possibly two other viral chemokines. vMIP-I and I-309 appear to act as CCR8 agonists: binding to and inducing cytosolic [Ca(2+)] elevation through the receptor. By contrast, vMIP-II and vMCC-I act as potent antagonists: binding without inducing signaling, and blocking the effects of I-309 and vMIP-I. These results suggest a ligand hierarchy for CCR8, identifying vMIP-I as a selective viral chemokine agonist. CCR8 may thus engage a specific subset of chemokines with the potential to regulate each other during viral infection and immune regulation. (+info)
Phosphoantigen-reactive Vgamma9Vdelta2 T lymphocytes suppress in vitro human immunodeficiency virus type 1 replication by cell-released antiviral factors including CC chemokines.
(51/1708)
Vgamma9Vdelta2 T lymphocytes are broadly reactive against various intracellular pathogens and display both lytic and proliferative responses to human immunodeficiency virus (HIV)-infected cells. HIV infection of peripheral blood mononuclear cell cultures led to absolute increases in Vgamma9Vdelta2 T cells accompanied by decreased p24 levels. Strong gammadelta T cell activation with nonpeptidic mycobacterial phosphoantigens (TUBAg1 extract or synthetic isopentenyl pyrophosphate) resulted in potent inhibition of HIV replication through soluble released factors. Subsequent analyses showed that phosphoantigen-activated gammadelta T cells produced substantial amounts of beta-chemokines (macrophage inflammatory protein [MIP]-1alpha, MIP-1beta, and regulated-on-activation, normal T-cell-expressed and -secreted beta-chemokine [RANTES]), which represent the natural ligand for the CCR5 HIV coreceptor. Accordingly, anti-beta-chemokine antibodies neutralized the inhibition of monocytotropic HIV strains by gammadelta T cell-released factors. Moreover, a T-tropic HIV strain using the CXCR4 coreceptor for virus entry was potently inhibited. Together, these data reveal that phosphoantigen-activated gammadelta T cells are an important source of CC chemokines and may suppress HIV replication through cell-released antiviral factors. (+info)
Cutting edge: immature dendritic cells generated from monocytes in the presence of TGF-beta 1 express functional C-C chemokine receptor 6.
(52/1708)
Although CD34+ progenitor-derived immature dendritic cells (DCs) express CCR6, several recent studies reported that monocyte-derived immature DCs do not do so. We observed that DCs generated from monocytes in the presence of GM-CSF, IL-4, and TGF-beta 1 consistently responded to liver and activation-regulated chemokine (LARC, also known as macrophage inflammatory protein-3 alpha). These immature DCs expressed one class of high-affinity binding sites for LARC, and expressed both CCR6 mRNA and protein. Therefore, LARC-CCR6 interaction presumably also contributes to the regulation of trafficking of monocyte-derived DCs, and utilization of TGF-beta can potentially provide a ready source of CCR6+ monocyte-derived DCs for therapeutic purposes. (+info)
Sequence polymorphisms in the chemokines Scya1 (TCA-3), Scya2 (monocyte chemoattractant protein (MCP)-1), and Scya12 (MCP-5) are candidates for eae7, a locus controlling susceptibility to monophasic remitting/nonrelapsing experimental allergic encephalomyelitis.
(53/1708)
Experimental allergic encephalomyelitis (EAE), the principal animal model of multiple sclerosis, is genetically controlled. To date, 13 disease-modifying loci have been identified in the mouse by whole genome scanning using an F2 intercross between EAE-susceptible SJL/J and EAE-resistant B10.S/DvTe mice. Two quantitative trait loci (QTL), eae6 and eae7, on chromosome 11 were identified by classical marker-specific linkage analysis and interval mapping. Both QTL were reported to be associated with severity and duration of clinical signs. eae7 was subsequently shown to be a unique locus controlling the development of monophasic remitting/nonrelapsing EAE. In this study, composite interval mapping resolved eae6 into two linked QTL: eae6a at 0-13 cM is associated with disease severity, and eae6b at 19-28 cM associated with the duration of clinical signs. Additionally, composite interval mapping significantly refined the locations of eae6a, eae6b, and eae7, thereby facilitating systematic candidate gene screening by cDNA sequencing of SJL/J and B10.S/DvTe alleles. Sequence polymorphisms were not seen in Lif and IL12 beta, candidate genes for eae6a and eae6b, respectively. Similarly, cDNA sequence polymorphisms in Nos2, Scya3, Scya4, Scya5, Scya6, Scya7, Scya9, Scya10, and Scya11 were excluded as candidates for eae7. However, multiple sequence polymorphisms resulting in significant amino acid substitutions were identified in Scya1 (TCA-3), Scya2 (monocyte chemoattractant protein (MCP)-1), and Scya12 (MCP-5). Given the role of chemokines in EAE, these sequence polymorphisms are promising candidates for eae7, a locus associated with severity of clinical signs and susceptibility to the shorter, less severe monophasic remitting/nonrelapsing form of disease. (+info)
Cutting edge: developmental switches in chemokine responses during T cell maturation.
(54/1708)
We show that developmental transitions during thymocyte maturation are associated with dramatic changes in chemotactic responses to chemokines. Macrophage-derived chemokine, a chemokine expressed in the thymic medulla, attracts thymocytes only during a brief window of development, between the late cortical and early medullary stages. All medullary phenotypes (CD4 or CD8 single positive) but not immature thymocytes respond to the medullary stroma-expressed (and secondary lymphoid tissue-associated) chemokines secondary lymphoid-tissue chemokine and macrophage inflammatory protein-3beta. The appearance of these responses is associated with the phenotypic stage of cortex to medulla migration and with up-regulation of mRNA for the receptors CCR4 (for macrophage-derived chemokine and thymus and activation-regulated chemokine) and CCR7 (for secondary lymphoid-tissue chemokine and macrophage inflammatory protein-3beta). In contrast, most immature and medullary thymocytes migrate to thymus-expressed chemokine, an ability that is lost only with up-regulation of the peripheral homing receptor L-selectin during the latest stages of thymocyte maturation associated with export to the periphery. Developmental switches in chemokine responses may help regulate critical migratory events during T cell development. (+info)
Basophils are a major source of IL-4, which is a critical factor in the generation of allergic inflammation. Eotaxin induces chemotaxis mediated through the CC chemokine receptor 3 (CCR3) present on basophils as well as eosinophils and Th2 cells, thereby promoting cell recruitment. To determine whether eotaxin has other proinflammatory activity, we examined the effect of eotaxin on basophil IL-4 expression by flow cytometry. Eotaxin alone had no effect on basophil IL-4 production, but further increased allergen-stimulated IL-4 expression. Eotaxin also enhanced IL-4 release from purified basophils 2- to 4-fold, as determined by ELISA (p < 0.01). Addition of eotaxin to cultures resulted in a 40-fold left shift in the dose response to Ag. This effect was obtained with physiologic concentrations of eotaxin (10 ng/ml), was abrogated by an Ab to the CCR3 receptor, and was noted with other chemokine ligands of CCR3. Additionally, eotaxin augmented IL-3 priming of basophil IL-4 production in a synergistic manner (p < 0.01). In contrast, no priming was observed with either IL-5 or GM-CSF. These results establish a novel function for eotaxin and other chemokine ligands of CCR3: the potentiation of Ag-mediated IL-4 production in basophils, and suggest a potential nonchemotactic role for CC chemokines in the pathogenesis and amplification of inflammation. (+info)
Induction of eotaxin expression and release from human airway smooth muscle cells by IL-1beta and TNFalpha: effects of IL-10 and corticosteroids.
(56/1708)
Eotaxin is a novel C-C chemokine with selective chemoattractant activity for eosinophils. We determined whether eotaxin could be produced by human airway smooth muscle (HASM) cells in culture and examined its regulation by interleukin-10 (IL-10) and the corticosteroid, dexamethasone. Stimulation of the cells with interleukin-1beta (IL-1beta) or tumour necrosis factor (TNFalpha) each at 10 ng ml(-1) induced the release of eotaxin protein with maximal accumulation by 24 h. Interferon-gamma (IFNgamma) alone at 10 ng ml(-1) had no effect and there was no synergy between these cytokines on the release of eotaxin. Reverse phase high performance liquid chromatographic (HPLC) analysis of supernatents from cells treated with TNFalpha (10 ng ml(-1) for 96 h showed immunoreactivity to eotaxin which eluted with the expected retention time of 34.5-35 min. Both IL-1beta and TNFalpha-induced release of eotaxin was not inhibited by dexamethasone (1 microM), however IL-10 (10 ng ml(-1)) had a significant inhibitory effect. Dexamethasone and IL-10 did not inhibit the induction of eotaxin mRNA induced by IL-1beta or TNFalpha. Thus, human airway smooth muscle cells can release eotaxin and could be an important source of chemokine production during airway inflammatory events. (+info)