IFN-gamma-inducible expression of thymus and activation-regulated chemokine/CCL17 and macrophage-derived chemokine/CCL22 in epidermal keratinocytes and their roles in atopic dermatitis.
(41/183)
Thymus and activation-regulated chemokine (TARC)/CCL17 and macrophage-derived chemokine (MDC)/CCL22 are a pair of CC chemokines known to selectively attract T(h)2 type memory T cells via CCR4. Here we examined circulating levels of TARC and MDC in patients with atopic dermatitis (AD) and control subjects by using plasma samples, which reflect blood contents of chemokines more accurately than serum samples. The plasma levels of TARC and MDC were significantly elevated in AD patients. These values also strongly correlated with disease severity and serum lactate dehydrogenase levels, and weakly correlated with serum total IgE levels and blood eosinophilia. Previous studies demonstrated TARC immunoreactivity in the epidermal layer of AD lesional skin and production of TARC by a human keratinocytic cell line HaCaT upon stimulation with IFN-gamma. Here we demonstrated MDC immunoreactivity in the epidermal layer of AD skin at levels stronger than that of TARC. Furthermore, primary epidermal keratinocytes expressed both TARC and MDC mRNA upon stimulation with IFN-gamma, but efficiently secreted only MDC. These results suggest a post-transcriptional regulation in TARC production. IFN-gamma also induced TARC and MDC mRNA in mouse skin. Collectively, both TARC and MDC play important roles in the local accumulation of T(h)2 cells in AD lesional skin. Production of T(h)2-attracting chemokines by epidermal keratinocytes upon treatment with IFN-gamma, which is also the potent inducer of T(h)1-attracting chemokines, may underline the pivotal role of IFN-gamma in the chronic phase of AD where both T(h)1 and T(h)2 responses are mixed. (+info)
Quantitative differences in chemokine receptor engagement generate diversity in integrin-dependent lymphocyte adhesion.
(42/183)
Chemokines control the specificity of lymphocyte homing. Numerous chemokines have been identified but the significance of redundancy in chemokine networks is unexplained. Here we investigated the biological significance of distinct chemokines binding to the same receptor. Among CCR4 ligands, skin vessels endothelial cells present C-C chemokine ligand (CCL) 17 but not CCL22 consistent with CCL17 involvement in T lymphocyte arrest on endothelial cells. However, CCL22 is much more powerful than CCL17 in the induction of rapid integrin-dependent T cell adhesion on VCAM-1 under conditions of physiological flow. The dominance of CCL22 over CCL17 extends to other CCR4-mediated phenomena such as receptor desensitization and internalization and correlates with the peculiar kinetics of CCR4 engagement by the two ligands. A similar phenomenological pattern is also shown for CXC chemokine ligand 9 and CXC chemokine ligand 11, which share binding to CXCR3. Our analysis shows how quantitative variations in chemokine receptor expression level and ligand engagement may alter the selectivity of integrin-dependent lymphocyte adhesive responses, suggesting a mechanism by which chemokine networks may either generate or break the specificity of lymphocyte subset recruitment. (+info)
Expression of T lymphocyte chemoattractants and activation markers in vernal keratoconjunctivitis.
(43/183)
BACKGROUND/AIMS: T lymphocytes are present in increased numbers in the conjunctiva of patients with vernal keratoconjunctivitis (VKC) and their activation has a central role in the pathogenesis of the chronic allergic inflammatory reactions seen in VKC. The aims of this study were to examine the expression of three recently described potent T lymphocyte chemoattractants, PARC (pulmonary and activation regulated chemokine), macrophage derived chemokine (MDC), and I-309, the MDC receptor CCR4, and T lymphocyte activation markers, CD25, CD26, CD62L, CD71, and CD30, and to correlate them with the counts of CD3(+) T lymphocytes in the conjunctiva of patients with VKC. METHOD: Conjunctival biopsy specimens from 11 patients with active VKC, and eight control subjects were studied by immunohistochemical techniques using a panel of monoclonal and polyclonal antibodies directed against PARC, MDC, I-309, CCR4, CD25, CD26, CD62L, CD71, and CD30. The numbers of positively stained cells were counted. The phenotype of inflammatory cells expressing chemokines was examined by double immunohistochemistry. RESULTS: In the normal conjunctiva, vascular endothelial cells in the upper substantia propria showed weak immunoreactivity for CD26. There was no immunoreactivity for the other antibodies. VKC specimens showed inflammatory cells expressing PARC, MDC, and I-309. The numbers of PARC(+) inflammatory cells were higher than the numbers of MDC(+) and I-309(+) inflammatory cells and the mean values of the three groups differed significantly (17.0 (SD 10.1); 9.5 (9.9), and 4.3 (7.9), respectively, p = 0.0117, ANOVA). The numbers of PARC(+) inflammatory cells had the strongest correlation with the numbers of CD3(+) T lymphocytes. Few CCR4(+) inflammatory cells were observed in only three specimens. Double immunohistochemistry revealed that all inflammatory cells expressing chemokines were CD68(+) monocytes/macrophages. The numbers of CD25(+) T lymphocytes were higher than the numbers of CD26(+), CD62L(+), CD71(+), and CD30(+) T lymphocytes and the mean values of the five groups differed significantly (46.2 (27.9), 30.7 (16.0), 20.1 (8.6), 7.8 (7.7), and 6.5 (4.0), respectively, p <0.001, ANOVA). The numbers of CD25(+) T lymphocytes had the strongest correlation with the numbers of CD3(+) T lymphocytes. CONCLUSION: These results suggest a potential role for PARC, MDC, and I-309 in attracting T lymphocytes into conjunctiva in VKC. T lymphocytes in VKC are activated and express several activation markers which might contribute to the pathogenesis of VKC. (+info)
Multiple determinants are involved in HIV coreceptor use as demonstrated by CCR4/CCL22 interaction in peripheral blood mononuclear cells (PBMCs).
(44/183)
Although a number of chemokine receptors display coreceptor activities in vitro, chemokine receptor 5 (CCR5) and CXC chemokine receptor 4 (CXCR4) remain the major coreceptors used by the human immunodeficiency virus type 1 (HIV-1). In this study, we used an envelope-mediated fusion assay to demonstrate low CCR4 coreceptor activity with some primary HIV-1 and simian immunodeficiency virus-1 (mac316) isolates in vitro. The coreceptor activity was sensitive to CCR4-specific antibodies and to the CCR4-specific chemokine ligand macrophage-derived chemokine (MDC)/chemokine ligand 22 (CCL22). Treatment of peripheral blood mononuclear cells (PBMCs; which express high levels of CCR4) with CCL22 caused down-modulation of endogenous CCR4 but had no significant effect on HIV-1 entry, suggesting that CCR4 may not be used as an entry coreceptor. Despite expression of other minor coreceptors on PBMCs, CCR5 and CXCR4 are preferentially used by HIV-1 isolates, as shown by chemokine-inhibition data. To determine the factors involved in this selective use, we analyzed CCR4 coreceptor activity and compared it with CCR5 use in PBMCs. We used a quantitative fluorescence-activated cell-sorting assay to estimate the numbers of CCR4 and CCR5 antibody-binding sites (ABS) on PBMCs. Although CCR4 was found on a higher percentage of CD4(+) cells, CCR5 ABS was twofold greater than CCR4 ABS on CD4(+) cells. Confocal microscopy revealed strong cell-surface CD4/CCR5 but weak CD4/CCR4 colocalization in PBMCs. Binding studies demonstrated that soluble gp120 had greater affinity to CCR5 than CCR4. The results suggested that coreceptor density, colocalization with CD4, and affinity of the viral gp120 to the coreceptor may determine preferential coreceptor use by HIV-1. (+info)
Cutting edge: differential chemokine production by myeloid and plasmacytoid dendritic cells.
(45/183)
To examine the different roles of myeloid dendritic cells (M-DCs) and plasmacytoid dendritic cells (P-DCs) in the induction and regulation of immune response, we have studied chemokine secretion by freshly isolated DC subsets in response to bacterial, viral, and T cell-derived stimuli. M-DCs selectively produced very high levels of the homeostatic chemokines CC chemokine ligand (CCL)17 and CCL22, while P-DCs produced very little if any. In contrast, the proinflammatory chemokine CCL3 was secreted mostly by P-DCs, whereas CCL4 and CXC chemokine ligand 8 were produced by both subsets. The selective production of CCL17 and CCL22 by M-DCs but not P-DCs was confirmed in vivo by immunohistology on human reactive lymph node sections. The high production of CCR4 ligands by M-DCs suggests their capacity to selectively recruit at sites of inflammation T cells with regulatory properties or with a Th2 phenotype, whereas P-DCs, by preferentially secreting CCR1/CCR5 ligands, would mostly recruit effector T cells and, in particular, Th1-type cells. (+info)
Increased CCR4 expression in cutaneous T cell lymphoma.
(46/183)
Chemokines are critical molecules in leukocyte trafficking, promoting site-specific migration to various tissues. The chemokine receptor CCR4 has recently been associated with skin-homing T cells. In view of the potential importance of CCR4 in skin homing of T cells, we investigated the expression pattern of CCR4 and its ligands TARC/CCL17 and MDC/CCL22 in the peripheral blood and skin of patients with cutaneous T cell lymphoma, a putative malignancy of the skin-homing T cells. In this study we analyzed the pattern of coexpression of the skin-homing molecules cutaneous lymphocyte antigen (CLA) and CCR4 in the blood and skin of patients with cutaneous T cell lymphoma. In the blood of cutaneous T cell lymphoma patients with peripheral blood involvement we found significantly increased percentages of T cells displaying the skin-homing phenotype (CLA+CCR4+) compared with healthy individuals. T cells expressing CLA and CCR4 were also found at high levels in cutaneous T cell lymphoma lesions along with abundant expression of the two CCR4 ligands TARC/CCL17 and MDC/CCL22. These data may explain, in part, why these T cells accumulate in the skin, a diagnostic feature of cutaneous T cell lymphomas. (+info)
The role of CCL22 (MDC) for the recruitment of eosinophils during allergic pleurisy in mice.
(47/183)
Eosinophils are important inflammatory cells in allergic diseases. In the present study, we have investigated the effects of CCL22 on the recruitment of eosinophils in vivo and in vitro. CCL22 induced a dose- and time-dependent recruitment of eosinophils into the pleural cavity of mice, and this was dependent on the release of platelet-activating factor (PAF) and subsequent generation of CCL11. However, in an allergic pleurisy model, an anti-CCL22 polyclonal antibody given during sensitization or before challenge had no significant effect on eosinophil recruitment. CCL22 did not induce eosinophil chemotaxis in vitro but was able to induce eosinophil degranulation in vitro and in vivo. In conclusion, we show that although exogenously added CCL22 may induce eosinophil migration in vivo via release of PAF and CCL11 (eotaxin), endogenous production of CCL22 does not drive eosinophil migration during allergic inflammation. However, CCL22 may be an important activator of eosinophils once these cells have migrated into tissue. (+info)
Mononuclear cell-infiltrate inhibition by blocking macrophage-derived chemokine results in attenuation of developing crescentic glomerulonephritis.
(48/183)
Glomerular monocyte/macrophage (Mo/M phi) infiltrates play a role in many forms of glomerulonephritis (GN), and the intensity of Mo/M phi trafficking correlates with the loss of renal function and histological damage. We analyzed the functional role of macrophage-derived chemokine (MDC), a potent mononuclear cell chemoattractant, during the progression of anti-glomerular basement membrane (GBM) antibody (Ab) GN, a model of crescentic GN in the WKY rat, and whether the effects of MDC were dependent on its receptor CCR4. MDC mRNA and protein expression were markedly induced in nephritic glomeruli throughout the disease. Blocking the function of MDC did not affect the developing of the disease from days 2 to 7, but it dramatically blocked M omicron/M phi infiltration in the glomeruli, prevented crescent formation, and reversed renal function impairment during days 7 to 14 of the anti-GBM GN. In this study, we also found that MDC activity on M omicron/M phi in this GN was at least partly dependent on a new variant of CCR4. These results suggest that MDC is critically involved in the development of anti-GBM GN from acute glomerular injury to irreversible tissue damage. In addition, an antagonist to MDC may represent a prime drug target for therapeutic application to intervene in the progression of anti-GBM GN and in other M omicron/M phi-dominant GN. (+info)