Enhanced airway Th2 response after allergen challenge in mice deficient in CC chemokine receptor-2 (CCR2)

To evaluate the role of CCR2 in allergic asthma, mutant mice deficient in CCR2 (CCR2(-/-)) and intact mice were sensitized with i.p. OVA with alum on days 0 and 7, and challenged by inhalation with nebulization of either OVA or saline. Airway hyperreactivity, measured by the methacholine-provoked increase in enhanced pause, was significantly increased (p < 0.05) in OVA-challenged CCR2(-/-) mutant mice, compared with comparably challenged CCR2(+/+) mice. OVA-challenged CCR2(-/-) mutants also were also found to have enhanced bronchoalveolar lavage fluid eosinophilia, peribronchiolar cellular cuffing, and Ig subclass switching, with increase in OVA-specific IgG(1) and IgE. In addition, RNase protection assay revealed increased whole lung expression of IL-13 in OVA-challenged CCR2(-/-) mutants. Unexpectedly, serum monocyte chemotactic protein-1 levels were 8-fold higher in CCR2(-/-) mutants than in CCR2(+/+) mice sensitized to OVA, but OVA challenge had no additional effect on circulating monocyte chemotactic protein-1 in either genotype. Ag stimulation of lymphocytes isolated from OVA-sensitized CCR2 mutants revealed a significant increase (p < 0.05) in IL-5 production, which differed from OVA-stimulated lymphocytes from sensitized CCR2(+/+) mice. These experiments demonstrate an enhanced response in airway reactivity and in lung inflammation in CCR2(-/-) mutant mice compared with comparably sensitized and challenged CCR2(+/+) mice. These observations suggest that CC chemokines and their receptors are involved in immunomodulation of atopic asthma.

Coregulation of CXC chemokine receptor and CD4 expression on T lymphocytes during allogeneic activation

Upon activation, naive T cells alter their migratory patterns, acquiring the ability to move through peripheral tissues as well as the general lymphoid circulation. Although the mechanisms responsible for these alterations are not well understood, changes in chemokine receptor expression may play a critical role. To investigate these changes, the expression patterns of two chemokine receptors, CXCR3 and CXCR4, were compared on CD4(+) T cells following activation in the MLR. By day 9 of activation, expression of the inflammatory chemokine receptor CXCR3 was up-regulated, while expression of the homeostatic chemokine receptor CXCR4 was down-regulated. Alterations in receptor expression occurred almost exclusively on a subpopulation of T cells that expressed higher levels of CD4. These CD4(high) T cells demonstrated many characteristics of activated T cells and had undergone division in the MLR. By day 9 of culture, the majority of CXCR3(+) and CXCR4(-) cells had divided and had acquired an activated/memory phenotype (CD45RA(-) CD45RO(+) CD69(+) CD25(+)). The levels of transcripts for both CXCR3 and CXCR4 were increased upon allo-activation. The discrepancy between levels of CXCR4 mRNA and surface protein was not due to sequestration of the receptor in intracellular compartments, as CXCR4 was not detectable intracellularly. However, intracellular CXCR3 was readily detectable. Finally, cells from allogeneic cultures demonstrated enhanced migration toward IFN-inducible T cell alpha chemoattractant and reduced migration toward stromal cell-derived factor-1 compared with syngeneic controls, thus suggesting that the observed switch in receptor expression may at least partly contribute to the differential patterns of migration displayed by naive and memory T cells.

Expression and characterization of the chemokine receptors CCR2 and CCR5 in mice

The chemokine receptors CCR2 and CCR5 play important roles in the recruitment of monocytes/macrophages and T cells. To better understand the role of both receptors in murine models of inflammatory diseases and to recognize potential problems when correlating these data to humans, we have generated mAbs against murine CCR2 and CCR5. In mice CCR2 is homogeneously expressed on monocytes and on 2--15% of T cells, closely resembling the expression pattern in humans. In contrast to humans, murine NK cells are highly CCR5 positive. In addition, CCR5 is expressed on 3--10% of CD4 and 10--40% of CD8-positive T cells and is weakly detectable on monocytes. Using a model of immune complex nephritis, we examined the effects of inflammation on chemokine receptor expression and found a 10-fold enrichment of CCR5(+) and CCR2(+) T cells in the inflamed kidneys. The activity of various chemokines and the antagonistic properties of the mAbs were measured by ligand-induced internalization of CCR2 and CCR5 on primary leukocytes. The Ab MC-21 (anti-CCR2) reduced the activity of murine monocyte chemotactic protein 1 by 95%, whereas the Ab MC-68 (anti-CCR5) blocked over 99% of the macrophage-inflammatory protein 1alpha and RANTES activity. MC-21 and MC-68 efficiently blocked the ligand binding to CCR2 and CCR5 with an IC(50) of 0.09 and 0.6--1.0 microg/ml, respectively. In good correlation to these in vitro data, MC-21 almost completely prevented the influx of monocytes in thioglycollate-induced peritonitis. Therefore, both Abs appear as useful reagents to further study the role of CCR2 and CCR5 in murine disease models.

Regulated MIP-3alpha/CCL20 production by human intestinal epithelium: mechanism for modulating mucosal immunity

Human intestinal epithelial cells secrete an array of chemokines known to signal the trafficking of neutrophils and monocytes important in innate mucosal immunity. We hypothesized that intestinal epithelium may also have the capacity to play a role in signaling host adaptive immunity. The CC chemokine macrophage inflammatory protein (MIP)-3alpha/CCL20 is chemotactic for immature dendritic cells and CD45RO(+) T cells that are important components of the host adaptive immune system. In these studies, we demonstrate the widespread production and regulated expression of MIP-3alpha by human intestinal epithelium. Several intestinal epithelial cell lines were shown to constitutively express MIP-3alpha mRNA. Moreover, MIP-3alpha mRNA expression and protein production were upregulated by stimulation of intestinal epithelial cells with the proinflammatory cytokines tumor necrosis factor-alpha or interleukin-1alpha or in response to infection with the enteric bacterial pathogens Salmonella or enteroinvasive Escherichia coli. In addition, MIP-3alpha was shown to function as a nuclear factor-kappaB target gene. In vitro findings were paralleled in vivo by increased expression of MIP-3alpha in the epithelium of cytokine-stimulated or bacteria-infected human intestinal xenografts and in the epithelium of inflamed human colon. Mucosal T cells, other mucosal mononuclear cells, and intestinal epithelial cells expressed CCR6, the cognate receptor for MIP-3alpha. The constitutive and regulated expression of MIP-3alpha by human intestinal epithelium is consistent with a role for epithelial cell-produced MIP-3alpha in modulating mucosal adaptive immune responses.

Hippocampal injury and alterations in neuronal chemokine co-receptor expression in patients with AIDS

Hippocampal neurons express high levels of HIV chemokine co-receptors, activation of which causes injury or death in vitro. To determine if their in vivo expression correlates with injury, we evaluated neuronal CXCR4 and CCR5 immunoreactivity and reactive gliosis in autopsy hippocampus of 10 control cases, 11 AIDS cases without HIV encephalitis (HIVnE) or opportunistic infections/lymphomas (OI/L), and 11 AIDS cases with HIV encephalitis (HIVE). All groups had higher CXCR4 and CCR5 expression in CA3 and CA4 neurons than CA1 neurons (p < 0.05). HIVE cases had increased neuronal CXCR4 and decreased neuronal CCR5 expression as well as increased numbers of hippocampal GFAP-positive astrocytes and LN3-positive microglia. Changes were most severe in CA3 and CA4 and lowest in CA1 regions. These findings also were noted in the 4 HIVE cases with neither hippocampal HIVE nor brain OI/L and in the HIVnE groups. This study quantitates the regional distribution of hippocampal neuronal CXCR4 and CCR5 and shows their respective increase and decrease in AIDS. It suggests a relationship between neuronal loss and gliosis with intensity of neuronal chemokine expression and raises the possibility of a selective vulnerability of hippocampal neurons to AIDS-related injury.

Dendritic cells injected via different routes induce immunity in cancer patients

Dendritic cells (DC) represent potent APCs that are capable of generating tumor-specific immunity. We performed a pilot clinical trial using Ag-pulsed DC as a tumor vaccine. Twenty-one patients with metastatic prostate cancer received two monthly injections of DC enriched and activated from their PBMC. DC were cocultured ex vivo with recombinant mouse prostatic acid phosphatase as the target neoantigen. Following enrichment, DC developed an activated phenotype with up-regulation of CD80, CD86, and CD83 expression. During culture, the DC maintained their levels of various adhesion molecules, including CD44, LFA-1, cutaneous lymphocyte-associated Ag, and CD49d, up-regulated CCR7, but lost CD62 ligand and CCR5. In the absence of CD62 ligand, such cells would not be expected to prime T cells efficiently if administered i.v. due to their inability to access lymphoid tissue via high endothelial venules. To assess this possibility, three patient cohorts were immunized with Ag-pulsed DC by i.v., intradermal (i.d.), or intralymphatic (i.l.) injection. All patients developed Ag-specific T cell immune responses following immunization, regardless of route. Induction of IFN-gamma production, however, was seen only with i.d. and i.l. routes of administration, and no IL-4 responses were seen regardless of route, consistent with the induction of Th1-type immunity. Five of nine patients who were immunized by the i.v. route developed Ag-specific Abs compared with one of six for i.d. and two of six for i.l. routes. These results suggest that while activated DC can prime T cell immunity regardless of route, the quality of this response and induction of Ag-specific Abs may be affected by the route of administration.

Malaria enhances expression of CC chemokine receptor 5 on placental macrophages

Malaria and human immunodeficiency virus (HIV) coinfections are common in pregnant women in sub-Saharan Africa. The current study shows that placentas of malaria-infected women contain 3 times as much CC chemokine receptor 5 (CCR5) RNA as placentas of women without malaria. By immunohistochemistry, CCR5(+) maternal macrophages were seen in placentas from malaria-infected women but not in placentas from malaria-uninfected women. In addition, CCR5 also was found on fetal Hofbauer cells in placentas from both groups. Thus, malaria infections increase the potential reservoir for HIV in the placenta by increasing the number of HIV target cells.

Compartmentalization of Peyer's patch anlagen before lymphocyte entry

We have shown that Peyer's patch (PP) first develops as a simple and even cell aggregation during embryogenesis. To investigate when and how such a simple cell aggregation forms the complex PP architecture, we analyzed the distribution of cells expressing IL-7R alpha (PP inducer cells), VCAM-1 (mesenchymal cells), CD11c (dendritic cells), and mature lymphocytes by whole-mount immunostaining of 17.5 days post coitus to 2 days postpartum mouse gut. Our results show that compartmentalization of PP anlagen commences at day 18.5 of gestation by clustering and subsequent follicle formation of IL-7R alpha(+), VCAM-1(+), and CD11c(+) cells. This process adds the primitive architecture of PP anlage with several follicles in which IL-7R alpha(+) cells localize in the center, while VCAM-1(+) and CD11c(+) cells localize at the fringe. This follicle formation is accompanied by the establishment of PP-specific vascular network expressing mucosal addressin cellular adhesion molecule-1. Mature B and T lymphocytes entering in the PP anlage are distributed promptly to their own target zones; B cells to the follicle and T cells to nonfollicular zones. Our analysis of scid/scid mouse indicate that the initial processes including formation of PP-specific vascular network occur in the absence of lymphocytes. These observations indicate that the basic architecture of PP is formed by a set of cell lineages assembled during the initial phase of induction of PP anlagen before entry of mature lymphocytes.

CXC chemokine receptor 2 but not C-C chemokine receptor 1 expression is essential for neutrophil recruitment to the cornea in helminth-mediated keratitis (river blindness)

Infiltration of neutrophils and eosinophils into the mammalian cornea can result in loss of corneal clarity and severe visual impairment. To identify mediators of granulocyte recruitment to the corneal stroma, we determined the relative contribution of chemokine receptors CXC chemokine receptor (CXCR)-2 (IL-8R homologue) and CCR1 using a murine model of ocular onchocerciasis (river blindness) in which neutrophils and eosinophils migrate from peripheral vessels to the central cornea. CXCR2(-/-) and CCR1(-/-) mice were immunized s.c. and injected into the corneal stroma with Ags from the parasitic helminth Onchocerca volvulus. We found that production of macrophage-inflammatory protein (MIP)-2, KC, and MIP-1 alpha was localized to the corneal stroma, rather than to the epithelium, which was consistent with the location of neutrophils in the cornea. CCR1 deficiency did not inhibit neutrophil or eosinophil infiltration to the cornea or development of corneal opacification. In marked contrast, neutrophil recruitment to the corneas of CXCR2(-/-) mice was significantly impaired (p < 0.0001 compared with control, BALB/c mice) with only occasional neutrophils detected in the central cornea. Furthermore, CXCR2(-/-) mice developed only mild corneal opacification compared with BALB/c mice. These differences were not due to impaired KC and MIP-2 production in the corneal stroma of CXCR2(-/-) mice, which was similar to BALB/c mice. Furthermore, although MIP-1 alpha production was lower in CXCR2(-/-) mice than BALB/c mice, eosinophil recruitment to the cornea was not impaired. These observations demonstrate the critical role for CXCR2 expression in neutrophil infiltration to the cornea and may indicate a target for immune intervention in neutrophil-mediated corneal inflammation.

General suppression of macrophage gene expression during Leishmania donovani infection

Within the mammalian host, Leishmania donovani is an obligatory intracellular protozoan that resides and multiplies exclusively in the phagolysosomes of macrophages. The outcome of this infection is governed by the interaction between Leishmania and macrophage molecules that ultimately effect the expression of genes within both cells. To explore the effect of this intracellular infection on macrophage gene expression, a cDNA expression array analysis was performed to compare gene expression profiles in noninfected and L. donovani-infected macrophages. In this manner, it was possible to examine the effect of infection on the expression of several hundred well-characterized host cell genes in an unbiased manner. Interestingly, approximately 40% of the genes whose expression was detected in macrophages were down-regulated during infection with L. donovani. However, several genes were also induced during the infection process, some of which could play a role in recruitment of additional macrophages to the site of infection. Taken together, the general suppression of gene expression in addition to the selective induction of key genes is likely to play an important role in allowing the parasite to survive and proliferate within its host macrophage cell.

Skewed maturation of memory HIV-specific CD8 T lymphocytes

Understanding the lineage differentiation of memory T cells is a central question in immunology. We investigated this issue by analysing the expression of the chemokine receptor CCR7, which defines distinct subsets of naive and memory T lymphocytes with different homing and effector capacities and antiviral immune responses to HIV and cytomegalovirus. Ex vivo analysis of the expression of CD45RA and CCR7 antigens, together with in vitro analysis of the cell-division capacity of different memory CD8+ T-cell populations, identified four subsets of HIV- and CMV-specific CD8+ T lymphocytes, and indicated the following lineage differentiation pattern: CD45RA+ CCR7+ --> CD45RA- CCR7+ --> CD45RA- CCR7- --> CD45RA+ CCR7-. Here we demonstrate through analysis of cell division (predominantly restricted to the CCR7+ CD8+ T-cell subsets) that the differentiation of antigen-specific CD8+ T cells is a two-step process characterized initially by a phase of proliferation largely restricted to the CCR7+ CD8+ cell subsets, followed by a phase of functional maturation encompassing the CCR7- CD8+ cell subsets. The distribution of these populations in HIV- and CMV-specific CD8+ T cells showed that the HIV-specific cell pool was predominantly (70%) composed of pre-terminally differentiated CD45RA- CCR7- cells, whereas the CMV-specific cell pool consisted mainly (50%) of the terminally differentiated CD45RA+ CCR7- cells. These results demonstrate a skewed maturation of HIV-specific memory CD8+ T cells during HIV infection.

Stem cell factor and igE-stimulated murine mast cells produce chemokines (CCL2, CCL17, CCL22) and express chemokine receptors

OBJECTIVE AND DESIGN

In the present study we investigated the effect of SCF and/or IgE on histamine, TNF-alpha and chemokines released from bone marrow-derived mast cells (BMMC) as well as chemokine receptor expression.

MATERIAL AND METHODS

BMMC were derived from femoral bone marrow of CBA/J mice. The purity of BMMC was >98% after 3 weeks. BMMC (2.5 x 10(6) cells/well) were incubated in the presence or absence of either SCF, IgE plus DNP or a combination of SCF and IgE for 6 and 18 h. Cell-free supernatants were recovered to measure CC chemokines, TNF-alpha and histamine release utilizing ELISA assays. CC chemokine family receptors were detected by RT-PCR analysis, and confirmed using functional chemotactic assays.

RESULTS

Histamine levels were comparable between SCF and IgE stimulated cells, whereas TNF-alpha production was significantly greater after IgE compared to SCF stimulation. SCF and/or IgE-stimulated BMMC released CC chemokines, CCL22 (MDC), CCL17 (TARC) and CCL2 (MCP-1). Increased mRNA expression of CCR1, CCR2, CCR3, and CCR5 was detected in SCF and IgE-stimulated BMMCs. Functional chemotactic assays confirmed the expression data.

CONCLUSION

SCF and IgE can up-regulate the expression of chemokines and chemokine receptors on mast cells. Thus, SCF may play a significant role in their activation and inflammation during allergic responses.

Virus-specific CD8(+) T cells with type 1 or type 2 cytokine profile are related to different disease activity in chronic hepatitis C virus infection

The present study demonstrates that the quality of the virus-specific CD8(+) T cell responses, as detected by both enzyme-linked immunospot assay and specific MHC-peptide tetramers, changed in relation to the different disease activity in chronically hepatitis C virus-infected patients. Indeed, both the serum alanine transaminase and the hepatic flogosis levels were related directly to the frequencies of peripheral memory effector CD8(+) T cells producing IFN-gamma (Tc1), but inversely to the frequencies of those producing both IL-4 and IL-10 (Tc2). Longitudinal studies highlighted that Tc1 or Tc2 responses fluctuate in relation to the different phases of the disease in the same individual. Furthermore, the Tc1 or Tc2 phenotype correlates with tetramer-positive cells expressing either CXCR3 or CCR3, promoting differential tissue localization of these cells and the maintenance of T cell homeostasis. Finally, studies at the level of liver-infiltrating lymphocytes indicated that they produced both IFN-gamma and IL-4 with an evident bias towards the Tc1-like phenotype. Our studies suggest that the progressive fluctuation of Tc1 and Tc2 responses may play a fundamental role in maintaining a long-lasting low-level liver inflammation, and may constitute the basis for new therapeutic strategies of immune regulation.

T cell phenotypes of the normal nasal mucosa: induction of Th2 cytokines and CCR3 expression by IL-4

Mucosal environments such as that of the nose are points of first contact between the human organism and its environment. At these sites the immune system must be regulated to differentiate between and respond appropriately to pathogens and harmless contaminants. T cell-driven immune responses broadly fall into Th1- or Th2-type phenotypes, with increasing evidence that the recruitment of these T lymphocyte subsets is mediated by selective expression of specific chemokine receptors. We have investigated the immunology of the normal nasal mucosa. We show that nasal T cell lines from normal individuals, expanded by culture in IL-2, show reduced expression of the Th2-type cytokines IL-4 and IL-5 compared with lines derived from the blood of the same subjects. These T cells also show reduced expression of the Th2-selective chemokine receptor, CCR3, but similar levels of CCR4 compared with the blood-derived lines. This apparent suppression of Th2 cytokine and CCR3 expression by nasal T cells was reversed by addition of IL-4 to the culture medium. These data are consistent with the presence of a nasal mucosal microenvironment that suppresses Th2 responses and may represent a protective measure against atopic allergic disease in humans and a favoring of Th1 responses to infectious agents. In contrast, T cell expression of CCR1 was higher in the nose than in the blood regardless of the culture medium cytokine environment in keeping with a role for this receptor in tissue homing or lymphocyte activation.

Expression of CCR9 beta-chemokine receptor is modulated in thymocyte differentiation and is selectively maintained in CD8(+) T cells from secondary lymphoid organs

Chemokines appear to have an important role in the seeding of lymphoid progenitors in the thymus, the regulation of the coordinated movements of the maturing T cells within this organ, and the egress of the resulting naive T cells to secondary lymphoid organs. CCR9, the specific receptor for the beta-chemokine TECK/CCL25, is selectively expressed in thymus, lymph node, and spleen. Using a specific anti-CCR9 polyclonal antibody, K629, and a semiquantitative reverse transcriptase-polymerase chain reaction procedure, a detailed study of CCR9 expression in the thymus and secondary lymphoid organs was performed. The results show that CD4(+)CD8(+) double-positive thymocytes have the highest CCR9 expression in thymus. Single-positive CD8(+) thymocytes continue to express this receptor after abandoning the thymus as mature naive T cells, as suggested by the existence of a CD8(+)CD69(low)CD62L(high) CCR9(+) cell subset. Consistent with this, CD8(+) lymphocytes from lymph nodes, spleen, and Peyer patches express a functional CCR9, as its expression correlates with migration in response to CCL25. Conversely, CD4(+) thymocytes lose CCR9 before abandoning the thymus, and CD4(+) T cells from secondary lymphoid organs also lack CCR9 expression. Analysis of CCR9 expression in thymocytes from mice of different ages showed that CCR9 levels are affected by age, as this receptor is more abundant, and its response to CCL25 is more potent in newborn animals. Collectively, these results suggest that CCR9 has a role in thymocyte development throughout murine life, with clear differences between the CD4(+) and CD8(+) lineages.

Expression of chemokine receptors by lung T cells from normal and asthmatic subjects

The lung is an important tertiary lymphoid organ with constant trafficking of T cells through the lung in both health and disease. T cell migration is controlled by a combination of adhesion receptors and chemokines expressed on vascular endothelium and in the tissue, often in an organ-specific manner. This leads to selective accumulation of different T cell subsets, a process called lymphocyte homing. There is evidence for a distinct lung-homing pathway, but no specific lung-homing receptors have been described. We analyzed the chemokine receptor profile of lung T cells to determine the extent to which lung T cells shared homing pathways with other organs such as the gut and skin. In addition, we compared expression of receptors in normal and asthmatic individuals to determine whether different pathways were used in health and disease. We observed that lung T cells expressed a profile of chemokine and adhesion receptors distinct from that of gut- and skin-homing T cells although no chemokine receptor specific for the lung was found. In particular, lung T cells expressed CCR5 and CXCR3, but not CCR9 or cutaneous lymphocyte Ag, and only low levels of CCR4 and alpha(4)beta(7). No differences were observed between lung T cells from normal vs asthmatic subjects. This study provides added support for the concept of a lung-homing pathway separate from other mucosal organs such as the gut and suggests that the chemokine pathways that control T cell migration in normal homeostasis and Th2-type inflammatory responses are similar.

Interferon-inducible protein 10, monokine induced by interferon gamma, and interferon-inducible T-cell alpha chemoattractant are produced by thymic epithelial cells and attract T-cell receptor (TCR) alphabeta+ CD8+ single-positive T cells, TCRgammadelta+ T cells, and natural killer-type cells in human thymus

Strong reactivity for interferon-inducible protein 10 (IP-10), monokine induced by interferon gamma (Mig), and interferon-inducible T-cell alpha chemoattractant (I-TAC) was found in epithelial cells mainly localized to the medulla of postnatal human thymus. The CXC chemokine receptor common to the 3 chemokines (CXCR3) was also preferentially expressed in medullary areas of the same thymuses and appeared to be a property of 4 distinct populations: CD3+ T-cell receptor (TCR) alphabeta+ CD8+ single-positive (SP) T cells, TCRgammadelta+ T cells, natural killer (NK)-type cells, and a small subset of CD3+(low) CD4+ CD8+ TCRalphabeta+ double-positive (DP) T cells. IP-10, Mig, and I-TAC showed chemoattractant activity for TCRalphabeta+ CD8+ SP T cells, TCRgammadelta+ T cells, and NK-type cells, suggesting their role in the migration of different subsets of mature thymocytes during human thymus lymphopoiesis.

Chemokine receptor expressions and responsiveness of cord blood T cells

Chemokines and their receptors play a critical role in the selective attraction of various subsets of leukocytes. We examined the chemokine receptor expressions and responsiveness of cord blood (CB) T cells. Flow-cytometric analysis revealed that peripheral blood (PB) T cells expressed CCR-1, CCR-2, CCR-5, CCR-6, CXC chemokine receptor-3 (CXCR-3), and CXCR-4, while CB T cells expressed only CXCR-4 on their surface. Chemotactic migratory response of CB T cells to macrophage-inflammatory protein (MIP)-1alpha, monocyte chemoattractant protein-1, RANTES, MIP-3alpha, monokine induced by IFN-gamma, and IFN-gamma-inducible protein-10 was significantly impaired compared with those of PB T cells. In contrast, the ability of CB T cells to migrate to MIP-3beta, 6Ckine, and stromal cell-derived factor-1alpha was greater than that of PB T cells, and these events were correlated with the expression levels of CCR-7 and CXCR-4, respectively. Engagement of CD3 and CD28 specifically up-regulated CXCR-3 expression and chemotaxis to monokine induced by IFN-gamma and IFN-gamma-inducible protein-10, whereas this stimulation down-regulated CCR-7 expression and chemotaxis to MIP-3beta and 6Ckine in PB T cells, but not in CB T cells. These results suggest that PB T cells and CB T cells exhibit distinct chemokine responsiveness via different chemokine receptor repertoire.

Expression of the C-C chemokine receptor CCR3 in human airway epithelial cells

Chemokine-induced eosinophil chemotaxis is mediated primarily through the C-C chemokine receptor, CCR3. We have now detected CCR3 immunoreactivity on epithelial cells in biopsies of patients with asthma and other respiratory diseases. CCR3 mRNA was detected by Northern blot analysis after TNF-alpha stimulation of the human primary bronchial epithelial cells as well as the epithelial cell line, BEAS-2B; IFN-gamma potentiated the TNF-alpha-induced expression. Western blots and flow cytometry confirmed the expression of CCR3 protein. This receptor is functional based on studies demonstrating eotaxin-induced intracellular Ca(2+) flux and tyrosine phosphorylation of cellular proteins. The specificity of this functional response was confirmed by blocking these signaling events with anti-CCR3 mAb (7B11) or pertussis toxin. Furthermore, (125)I-eotaxin binding assay confirmed that CCR3 expressed on epithelial cells have the expected ligand specificity. These studies indicate that airway epithelial cells express CCR3 and suggest that CCR3 ligands may influence epithelial cell functions.

Increase of CCR1 and CCR5 expression and enhanced functional response to MIP-1 alpha during differentiation of human monocytes to macrophages

Chemokines and their receptors regulate migration of leukocytes under normal and inflammatory conditions. In this study, we analyzed the CC chemokine receptor (CCR) expression of monocytes differentiating in vitro to macrophages. We observed a time-dependent change of expression and functional responsiveness of CCR1, CCR2, and CCR5 within 48 h. Whereas freshly harvested monocytes were strongly attracted by monocyte chemotactic protein 1 (MCP-1), a specific ligand for CCR2, only a weak response was observed to macrophage inflammatory protein 1alpha (MIP-1alpha), which binds to CCR1 and CCR5. In striking contrast, differentiated macrophages displayed a strong chemotactic response to MIP-1alpha and only a weak response to MCP-1. These findings were paralleled by intracellular calcium shifts. During the time course of monocyte to macrophage differentiation, mRNA levels and surface expression of CCR2 decreased, whereas that of CCR1 and CCR5 increased. The time-dependent switch from CCR2 on monocytes to CCR1 and CCR5 on mature macrophages reflects a functional change belonging to the differentiation process of monocytes to macrophages and may form the basis for a differential responsiveness of monocytes and macrophages to distinct sets of chemokines.

Signaling events following chemokine receptor ligation in human dendritic cells at different developmental stages

Responsiveness of dendritic cells (DC) to inflammatory CC chemokines is down-regulated during their maturation. We analyzed the mechanism underlying these events. Cell-surface expression of CC chemokine receptor (CCR)-1, -3 and -5 was increased during differentiation of immature DC (iDC) from monocytes. In contrast, these expressions were decreased during development of iDC into mature DC (mDC) to levels similar to those of monocytes. Transcriptional expression of CCR-1, -3 and -5 was increased during differentiation of iDC from monocytes, while the expression was decreased during development of iDC into mDC. Expression of CCR-7 transcript was detected in mDC, but not in monocytes or iDC. Both monocytes and iDC, but not mDC, migrated in response to inflammatory CC chemokines such as regulated on activation normal T cell expressed and secreted (RANTES)/CCL5, whereas mDC, but not monocytes or iDC, migrated to macrophage inflammatory protein (MIP)-3ss/CCL19. Receptor engagement of monocytes or iDC by RANTES (for CCR-1, -3 and -5) resulted in protein tyrosine phosphorylation events including activation of focal adhesion kinase as well as mitogen-activated protein kinase, whereas this stimulation induced little activation of these molecular events in mDC when compared with monocytes or iDC. On the other hand, stimulation with MIP-3ss (for CCR-7) induced tyrosine phosphorylation events in mDC, but not in monocytes or iDC. These results suggest that the down-regulation of cell-surface expression of CCR and of their downstream signaling events may be involved in the reduced chemotaxis of DC to inflammatory CC chemokines during their maturation.

CCR4 memory CD4+ T lymphocytes are increased in peripheral blood and lesional skin from patients with atopic dermatitis

BACKGROUND

Recent studies have reported that TH1 and TH2 cells express CXCR3 and CCR4, respectively.

OBJECTIVE

Our goal was to assess the association of CCR4 and CXCR3 expression with TH2 and TH1 cells and association of CCR4 and CXCR3 expression with inflammation in patients with atopic dermatitis (AD).

METHODS

Intracellular cytokine production and chemokine receptor expression in blood T cells were examined by flow cytometry. Immunohistochemical expression of chemokine receptors was also investigated in chronically lesional skin.

RESULTS

CCR4+ and CXCR3+ CD4+ T cells predominantly produced IL-4 and IFN-gamma, respectively. Although the frequency of CXCR3+ cells among CD4+ CD45RO+ T cells was similar for patients with AD (n = 29) and healthy control subjects (n = 19), patients with severe AD (n = 14) had a reduced frequency of CXCR3+ cells. In contrast, the frequency of CCR4+ cells and the CCR4/CXCR3 ratio were higher in patients with AD (n = 22) than healthy control subjects (n = 16) and correlated with disease severity of AD. The frequency of CCR4+ cells correlated positively with eosinophil numbers and serum IgE levels, whereas the frequency of CXCR3+ cells correlated inversely with eosinophil numbers. The frequency of CCR4+ or CXCR3+ cells was similar in patients with psoriasis (n = 6) and healthy control subjects. Immunohistochemical analysis showed that the frequency of CCR4+ cells among CD4+ T cells in chronically lesional skin of patients with AD (n = 9) was higher than that of patients with psoriasis (n = 4).

CONCLUSION

Our data suggest the association of CCR4 expression with TH2 cells, the predominance of CCR4+ cells in blood from patients with AD, and an important role of CCR4 in the migration of TH2 cells from blood into AD lesional skin.

Expression and regulation of chemokine receptors in human natural killer cells

Using flow cytometric and RNase protection assays, this study examined the expression of chemokine receptors in nonactivated natural killer (NK) cells and compared this expression with NK cells activated with interleukin (IL)-2, which either adhered to plastic flasks (AD) or did not adhere (NA). None of the NK cell subsets expressed CXCR2, CXCR5, or CCR5. The major differences between these cells include increased expression of CXCR1, CCR1, CCR2, CCR4, CCR8, and CX(3)CR1 in AD when compared to NA or nonactivated NK cells. The chemotactic response to the CXC and CC chemokines correlated with the receptor expression except that all 3 populations responded to GRO-alpha, despite their lack of CXCR2 expression. Pretreatment of these cells with anti-CXCR2 did not inhibit the chemotactic response to GRO-alpha. In addition, nonactivated and NA cells responded to fractalkine, although they lack the expression of CX(3)CR1. This activity was not inhibited by anti-CX(3)CR1. Viral macrophage inflammatory protein (vMIP)-I, I-309, and TARC competed with the binding of (125)I-309 to AD cells with varying affinities. Transforming growth factor (TGF)-beta1 but not any other cytokine or chemokine examined including interferon (IFN)-gamma, MIP-3beta, macrophage-derived chemokine (MDC), thymus and activation-regulated chemokine (TARC) or I-309, up-regulated the expression of CXCR3 and CXCR4 on NK cell surface. This is correlated with increased chemotaxis of NK cells treated with TGF-beta1 toward stromal cell-derived factor (SDF)-1alpha and interferon-inducible protein-10 (IP-10). Messenger RNA for lymphotactin, RANTES, MIP-1alpha, and MIP-1beta, but not IP-10, monocyte chemotactic protein (MCP)-1, IL-8, or I-309 was expressed in all 3 NK cell subsets. Our results may have implications for the dissemination of NK cells at the sites of tumor growth or viral replication. (Blood. 2001;97:367-375)

CCR7 expression and memory T cell diversity in humans

CCR7, along with L-selectin and LFA-1, mediates homing of T cells to secondary lymphoid organs via high endothelial venules (HEV). CCR7 has also been implicated in microenvironmental positioning of lymphocytes within secondary lymphoid organs and in return of lymphocytes and dendritic cells to the lymph after passage through nonlymphoid tissues. We have generated mAbs to human CCR7, whose specificities correlate with functional migration of lymphocyte subsets to known CCR7 ligands. We find that CCR7 is expressed on the vast majority of peripheral blood T cells, including most cells that express adhesion molecules (cutaneous lymphocyte Ag alpha(4)beta(7) integrin) required for homing to nonlymphoid tissues. A subset of CD27(neg) memory CD4 T cells from human peripheral blood is greatly enriched in the CCR7(neg) population, as well as L-selectin(neg) cells, suggesting that these cells are incapable of homing to secondary lymphoid organs. Accordingly, CD27(neg) T cells are rare within tonsil, a representative secondary lymphoid organ. All resting T cells within secondary lymphoid organs express high levels of CCR7, but many activated cells lack CCR7. CCR7 loss in activated CD4 cells accompanies CXC chemokine receptor (CXCR)5 gain, suggesting that the reciprocal expression of these two receptors may contribute to differential positioning of resting vs activated cells within the organ. Lymphocytes isolated from nonlymphoid tissues (such as skin, lung, or intestine) contain many CD27(neg) cells lacking CCR7. The ratio of CD27(neg)/CCR7(neg) cells to CD27(pos)/CCR7(pos) cells varies from tissue to tissue, and may correlate with the number of cells actively engaged in Ag recognition within a given tissue.

Granulocyte-macrophage colony stimulating factor up-regulates CCR1 in human neutrophils

Neutrophils (polymorphonuclear leukocytes; PMN) are phagocytic cells instrumental in the clearance of infectious pathogens. Human PMN are commonly thought to respond primarily to chemokines from the CXC family. However, recent findings suggest that under specific cytokine activation conditions, PMN can also respond to some CC chemokines. In this study, the effect of GM-CSF, a well-characterized PMN priming and maturation factor, on CC-chemokine receptor (CCR) expression in PMN was investigated. Constitutive expression of CCR1 and CCR3 mRNA in PMN was detected by ribonuclease protection assay. Following incubation of PMN with GM-CSF (0.01-10 ng/ml; 6 h) CCR1 mRNA expression was rapidly (approximately 1 h) up-regulated. In contrast, no significant induction of CCR2, CCR3, CCR4, or CCR5 mRNA was observed. CCR1 protein was also up-regulated by GM-CSF stimulation. GM-CSF-induced up-regulation of CCR1 showed functional consequences because GM-CSF-treated PMN, but not control cells, responded to the CC chemokines macrophage inflammatory protein-1alpha, monocyte chemoattractant protein-3, and RANTES in assays of chemotactic migration and intracellular calcium mobilization. These results suggest that PMN activated by the proinflammatory cytokine GM-CSF can change their receptor expression pattern and become responsive to CC chemokines.

Chemokine receptor expression and function in CD4+ T lymphocytes with regulatory activity

We have investigated the chemokine receptor expression and migratory behavior of a new subset of nickel-specific skin-homing regulatory CD4(+) T cells (Th(IL-10)) releasing high levels of IL-10, low IFN-gamma, and undetectable IL-4. These cells inhibit in a IL-10-dependent manner the capacity of dendritic cells to activate nickel-specific Tc1 and Th1 lymphocytes. RNase protection assay and FACS analysis revealed the expression of a vast repertoire of chemokine receptors on resting Th(IL-10), including the Th1-associated CXCR3 and CCR5, and the Th2-associated CCR3, CCR4, and CCR8, the latter at higher levels compared with Th2 cells. The most active chemokines for resting Th(IL-10), in terms of calcium mobilization and in vitro migration, were in order of potency: CCL2 (monocyte chemoattractant protein-1, CCR2 ligand), CCL4 (macrophage-inflammatory protein-1beta, CCR5 ligand), CCL3 (macrophage-inflammatory protein-1alpha, CCR1/5 ligand), CCL17 (thymus and activation-regulated chemokine, CCR4 ligand), CCL1 (I-309, CCR8 ligand), CXCL12 (stromal-derived factor-1, CXCR4), and CCL11 (eotaxin, CCR3 ligand). Consistent with receptor expression down-regulation, activated Th(IL-10) exhibited a reduced or absent response to most chemokines, but retained a significant migratory capacity to I-309, monocyte chemoattractant protein-1, and thymus and activation-regulated chemokine. I-309, which was ineffective on Th1 lymphocytes, attracted more efficiently Th(IL-10) than Th2 cells. I-309 and CCR8 mRNAs were not detected in unaffected skin and were up-regulated at the skin site of nickel-allergic reaction, with an earlier expression kinetics compared with IL-10 and IL-4. Results indicate that skin-homing regulatory Th(IL-10) lymphocytes coexpress functional Th1- and Th2-associated chemokine receptors, and that CCR8/I-309-driven recruitment of both resting and activated Th(IL-10) cells may be critically involved in the regulation of Th1-mediated skin allergic disorders.

A distinct expression of CC chemokines by macrophages in nasopharyngeal carcinoma: implication for the intense tumor infiltration by T lymphocytes and macrophages

Nasopharyngeal carcinoma (NPC) is characterized by harboring Epstein-Barr virus genes in the tumor cells and an intense infiltration of leukocytes in the tumor tissue. These infiltrating cells are mainly composed of T lymphocytes and macrophages. The mechanism of this intense infiltration has long been a puzzle. We attempted to address this issue by studying the expression of CC chemokines, which are responsible for recruiting both T cells and macrophages, by an immunohistochemical approach. In biopsies obtained from nasopharynx of 17 NPC patients that contained tumor cells, expression of macrophage inflammatory protein 1alpha (MIP-1alpha), MIP-1beta, macrophage chemoattractant protein-1 (MCP-1), MCP-2, MCP-3, and RANTES was detected in the tumor-infiltrating cells, with MIP-1alpha and MCP-1 found in nearly all biopsies and the others relatively less frequently. Furthermore, expression of interferon-gamma (IFN-gamma) was also observed in tumor-infiltrating cells. In contrast, CC chemokines and IFN-gamma were rarely expressed in the 13 control biopsies that were either normal or with nonspecific inflammation, and in 4 biopsies from untreated NPC patients that contained no tumor cells. Using an immunofluorescent double-staining method, MIP-1alpha and MCP-1 were identified to be associated with macrophages, and IFN-gamma with T cells. Moreover, expression of CCR2 and CCR5, the receptors for these chemokines, was also detected in the tumor-infiltrating cells. These data indicate that the intense tumor infiltration by T cells and macrophages is a result of active recruitment. It seems possible that the intense infiltration of leukocytes in NPC tumor tissue is initiated by the activated tumor-reactive T cells. T cells migrate into the tumor tissue in an antigen-specific mode, and IFN-gamma secreted from these pioneer T cells activates tissue macrophages to express CC chemokines, especially MIP-1alpha and MCP-1, which consequently recruit more T cells and macrophages into the tumor tissue.

The chemokine RANTES is a crucial mediator of the progression from acute to chronic colitis in the rat

Chemokines have well characterized proinflammatory actions, including the ability to induce extravasation of leukocytes that participate in chronic inflammation. In this study, we evaluated the role of a C-C chemokine, RANTES, in the chronic phase of a rat model of colitis. Colitis was induced by intracolonic administration of trinitrobenzene sulfonic acid. At various timepoints thereafter (2 h to 14 days), colonic tissue levels of several chemokines were measured. Unlike the expression of monocyte chemoattractant protein-1, macrophage inflammatory protein-2, and cytokine-induced neutrophil chemoattractant, the expression of RANTES was significantly elevated during the chronic phase of colitis (> or =7 days after induction). Colonic RANTES mRNA expression was also significantly elevated during the chronic phase of colitis. The numbers of macrophages and monocytes in the colonic mucosa increased substantially during the chronic phase, as did expression of two of the receptors (CCR1 and CCR5) to which RANTES is known to bind. Administration on days 7 through 14 after trinitrobenzene sulfonic acid administration of a CCR1/CCR5 receptor antagonist, Met-RANTES, resulted in a significant reduction of both macroscopic and microscopic colonic damage, as well as reducing the recruitment into the colon of monocytes, mast cells, and neutrophils. In some rats, treatment with Met-RANTES resulted in a near-complete resolution of colonic damage and inflammation. These results suggest a crucial role of RANTES in the progression from acute to chronic inflammation in a rat model of colitis.

Effects of calcitriol and its analogues on interaction of MCP-1 and monocyte derived dendritic cells in vitro

AIM

To study the effect of calcitriol [1,25(OH)2D3] and its analogues on the interaction of monocyte chemoattractant protein-1 (MCP-1) and in vitro generated monocyte-derived dendritic cells (MoDC).

METHODS

MoDC were obtained by differentiating monocytes in exposure to GM-CSF and IL-4 for 5 d. mRNA expression of MCP-1 and its receptors were analyzed by RT-PCR, and protein production of MCP-1 by ELISA and migratory ability of MoDC in response to MCP-1 by a micromultiwell chemotaxis chamber assay.

RESULTS

MoDC can express MCP-1 mRNA, and secret a low level of MCP-1 protein and has the ability to migrate to MCP-1 in corresponding to its expression of MCP-1 receptors. Calcitriol and its analogues with the same affinity to vitamin D receptor up-regulated the gene expression of both MCP-1 and its receptors, enhanced MCP-1 protein production and promoted the migratory ability of MoDC to MCP-1.

CONCLUSION

The interaction of DC and MCP-1 found in this study may suggest a possible auto-regulatory role between DC and MCP-1 and the modulatory effect of calcitriol and its analogues on DC and MCP-1 might provide an understanding of their positive role in tumors.

Synovial stromal cells from rheumatoid arthritis patients attract monocytes by producing MCP-1 and IL-8

Macrophages that accumulate in the synovium of rheumatoid arthritis patients play an important role in the pathogenesis of this inflammatory disease. However, the mechanism by which macrophages are attracted into the inflamed synovium and accumulate there has not been completely delineated. The results of this study show that rheumatoid arthritis synovial stromal cells produce the chemokines monocyte chemotactic protein-1 and IL-8, and these have the capacity to attract peripheral monocytes. These results suggest that one of the mechanisms by which macrophages accumulate in the inflamed synovium is by responding to the chemokines produced locally.

The transient expression of C-C chemokine receptor 8 in thymus identifies a thymocyte subset committed to become CD4+ single-positive T cells

Developing T cells journey through the different thymic microenvironments while receiving signals that eventually will allow some of them to become mature naive T cells exported to the periphery. This maturation can be visualized by the phenotype of the developing cells. CCR8 is a ss-chemokine receptor preferentially expressed in the thymus. We have developed 8F4, an anti-mouse CCR8 mAb that is able to neutralize the ligand-induced activation of CCR8, and used it to characterize the CCR8 protein expression in the different thymocyte subsets. Taking into account the intrathymic lineage relationships, our data showed that CCR8 expression in thymus followed two transient waves along T cell maturation. The first one took place in CD4(-) CD8(-) double-negative thymocytes, which showed a low CCR8 expression, and the second wave occurred after TCR activation by the Ag-dependent positive selection in CD4(+) CD8(+) double-positive cells. From that maturation stage, CCR8 expression gradually increased as the CD4(+) cell differentiation proceeded, reaching a maximum at the CD4(+) CD8(-) single-positive stage. These CD4(+) cells expressing CCR8 were also CD69(high) CD62L(low) thymocytes, suggesting that they still needed to undergo some differentiation step before becoming functionally competent naive T cells ready to be exported from the thymus. Interestingly, no significant amounts of CCR8 protein were detectable in CD4(-) CD8(+) thymocytes. Our data showing a clear regulation of the CCR8 protein in thymus suggest a relevant role for CCR8 in this lymphoid organ, and identify CCR8 as a possible marker of thymocyte subsets recently committed to the CD4(+) lineage.

C-C chemokine receptor 4 expression defines a major subset of circulating nonintestinal memory T cells of both Th1 and Th2 potential

CCR4, a chemokine receptor for macrophage-derived chemokine (MDC) and thymus and activation-regulated chemokine (TARC), has been implicated as a preferential marker for Th2 lymphocytes. Following in vitro polarization protocols, most Th2 lymphocytes express CCR4 and respond to its ligands TARC and MDC, whereas Th1 lymphocytes express CXC chemokine receptor 3 and CCR5 (but not CCR4). We show in this study that CCR4 is a major receptor for MDC and TARC on T lymphocytes, as anti-CCR4 mAbs significantly inhibit the migration of these cells to MDC and TARC. CCR4 is also highly expressed in most single-positive CD4(+) thymocytes and on a major fraction of blood nonintestinal (alpha(4)beta(7)(-)) memory CD4 lymphocytes, including almost all skin memory CD4(+) cells expressing the cutaneous lymphocyte Ag (CLA), but weakly or not expressed in other subsets in thymus and blood. Interestingly, major fractions of circulating CCR4(+) memory CD4 lymphocytes coexpress the Th1-associated receptors CXC chemokine receptor 3 and CCR5, suggesting a potential problem in using these markers for Th1 vs Th2 lymphocyte cells. Moreover, although production of Th2 cytokines in blood T cells is associated with CCR4(+) CD4 lymphocytes, significant numbers of freshly isolated circulating CCR4(+) memory CD4 lymphocytes (including both CLA(+) and CLA(-) fractions) readily express the Th1 cytokine IFN-gamma after short-term stimulation. Our results are consistent with a role for CCR4 as a major trafficking receptor for systemic memory T cells, and indicate that the patterns and regulation of chemokine receptor expression in vivo are more complex than indicated by current in vitro models of Th1 vs Th2 cell generation.

Basophil responses to chemokines are regulated by both sequential and cooperative receptor signaling

To investigate human basophil responses to chemokines, we have developed a sensitive assay that uses flow cytometry to measure leukocyte shape change as a marker of cell responsiveness. PBMC were isolated from the blood of volunteers. Basophils were identified as a single population of cells that stained positive for IL-3Ralpha (CDw123) and negative for HLA-DR, and their increase in forward scatter (as a result of cell shape change) in response to chemokines was measured. Shape change responses of basophils to chemokines were highly reproducible, with a rank order of potency: monocyte chemoattractant protein (MCP) 4 (peak at <1 nM) >/= eotaxin-2 = eotaxin-3 >/= eotaxin > MCP-1 = MCP-3 > macrophage-inflammatory protein-1alpha > RANTES = MCP-2 = IL-8. The CCR4-selective ligand macrophage-derived chemokine did not elicit a response at concentrations up to 10 nM. Blocking mAbs to CCR2 and CCR3 demonstrated that responses to higher concentrations (>10 nM) of MCP-1 were mediated by CCR3 rather than CCR2, whereas MCP-4 exhibited a biphasic response consistent with sequential activation of CCR3 at lower concentrations and CCR2 at 10 nM MCP-4 and above. In contrast, responses to MCP-3 were blocked only in the presence of both mAbs, but not after pretreatment with either anti-CCR2 or anti-CCR3 mAb alone. These patterns of receptor usage were different from those seen for eosinophils and monocytes. We suggest that cooperation between CCRs might be a mechanism for preferential recruitment of basophils, as occurs in tissue hypersensitivity responses in vivo.

Cutting edge: C-C chemokine receptor 6 is essential for arrest of a subset of memory T cells on activated dermal microvascular endothelial cells under physiologic flow conditions in vitro

Memory T cells (mTC) express multiple chemokine receptors (including CCR4 and CCR6) that may potentially be involved in their arrest on inflamed endothelia. Herein, we specifically addressed whether CCR6 is required for mTC to arrest on TNF-alpha-activated human dermal microvascular endothelial cells (HDMEC) in vitro under shear stress conditions. Recombinant liver and activation-regulated chemokine (LARC)/CCL20 (a CCR6 ligand) induced firm arrest of cutaneous lymphocyte Ag(+) mTC in a flow chamber system using purified substrates. Strikingly, desensitization of CCR6 with LARC, but not thymus and activation-regulated chemokine/CCL17 or secondary lymphoid tissue chemokine/CCL21, caused a 50-75% decrease (p < 0. 001) in arrest of mTC on HDMEC, which was indistinguishable from the reduction observed when total mTC were treated with pertussis toxin (p > 0.5). CCR6-depleted mTC also had a markedly reduced ability to arrest on HDMEC. Our results suggest that LARC production by activated endothelial cells and CCR6 expression by mTC may be critical components in the pertussis toxin-sensitive arrest of mTC on activated HDMEC.

I-309 binds to and activates endothelial cell functions and acts as an angiogenic molecule in vivo

Several chemokines have been shown to act as angiogenic molecules or to modulate the activity of growth factors such as fibroblast growth factor 2 (FGF-2) and vascular endothelial growth factor (VEGF). The detection of the CC chemokine receptor (CCR) 8 message in human umbilical vein endothelial cells (HUVECs) by reverse transcription- polymerase chain reaction (RT-PCR) and RNase protection assay (RPA), prompted us to investigate the potential role exerted by the CC chemokine I-309, a known ligand of such receptor, in both in vitro and in vivo angiogenesis assays. We show here that I-309 binds to endothelial cells, stimulates chemotaxis and invasion of these cells, and enhances HUVEC differentiation into capillary-like structures in an in vitro Matrigel assay. Furthermore, I-309 is an inducer of angiogenesis in vivo in both the rabbit cornea and the chick chorioallantoic membrane assay (CAM).

Functional expression of CCR1, CCR3, CCR4, and CXCR4 chemokine receptors on human platelets

Platelets are known to contain platelet factor 4 and beta-thromboglobulin, alpha-chemokines containing the CXC motif, but recent studies extended the range to the beta-family characterized by the CC motif, including RANTES and Gro-alpha. There is also evidence for expression of chemokine receptors CCR4 and CXCR4 in platelets. This study shows that platelets have functional CCR1, CCR3, CCR4, and CXCR4 chemokine receptors. Polymerase chain reaction detected chemokine receptor messenger RNA in platelet RNA. CCR1, CCR3, and especially CCR4 gave strong signals; CXCR1 and CXCR4 were weakly positive. Flow cytometry with specific antibodies showed the presence of a clear signal for CXCR4 and weak signals for CCR1 and CCR3, whereas CXCR1, CXCR2, CXCR3, and CCR5 were all negative. Immunoprecipitation and Western blotting with polyclonal antibodies to cytoplasmic peptides clearly showed the presence of CCR1 and CCR4 in platelets in amounts comparable to monocytes and CCR4 transfected cells, respectively. Chemokines specific for these receptors, including monocyte chemotactic protein 1, macrophage inflammatory peptide 1alpha, eotaxin, RANTES, TARC, macrophage-derived chemokine, and stromal cell-derived factor 1, activate platelets to give Ca(++) signals, aggregation, and release of granule contents. Platelet aggregation was dependent on release of adenosine diphosphate (ADP) and its interaction with platelet ADP receptors. Part, but not all, of the Ca(++) signal was due to ADP release feeding back to its receptors. Platelet activation also involved heparan or chondroitin sulfate associated with the platelet surface and was inhibited by cleavage of these glycosaminoglycans or by heparin or low molecular weight heparin. These platelet receptors may be involved in inflammatory or allergic responses or in platelet activation in human immunodeficiency virus infection.

Tat protein is an HIV-1-encoded beta-chemokine homolog that promotes migration and up-regulates CCR3 expression on human Fc epsilon RI+ cells

Human basophils and mast cells express the chemokine receptor CCR3, which binds the chemokines eotaxin and RANTES. HIV-1 Tat protein is a potent chemoattractant for basophils and lung mast cells obtained from healthy individuals seronegative for Abs to HIV-1 and HIV-2. Tat protein induced a rapid and transient Ca(2+) influx in basophils and mast cells, analogous to beta-chemokines. Tat protein neither induced histamine release from human basophils and mast cells nor increased IL-3-stimulated histamine secretion from basophils. The chemotactic activity of Tat protein was blocked by preincubation of FcepsilonRI(+) cells with anti-CCR3 Ab. Preincubation of Tat with a mAb anti-Tat (aa 1-86) blocked the migration induced by Tat. In contrast, a mAb specific for the basic region (aa 46-60) did not inhibit the chemotactic effect of Tat protein. Tat protein or eotaxin desensitized basophils to a subsequent challenge with the autologous or the heterologous stimulus. Preincubation of basophils with Tat protein up-regulated the level of CCR3 mRNA and the surface expression of the CCR3 receptor. Tat protein is the first identified HIV-1-encoded beta-chemokine homologue that influences the directional migration of human FcepsilonRI(+) cells and the expression of surface receptor CCR3 on these cells.

CXC chemokine receptor 5 expression defines follicular homing T cells with B cell helper function

Leukocyte traffic through secondary lymphoid tissues is finely tuned by chemokines. We have studied the functional properties of a human T cell subset marked by the expression of CXC chemokine receptor 5 (CXCR5). Memory but not naive T cells from tonsils are CXCR5(+) and migrate in response to the B cell-attracting chemokine 1 (BCA-1), which is selectively expressed by reticular cells and blood vessels within B cell follicles. Tonsillar CXCR5(+) T cells do not respond to other chemokines present in secondary lymphoid tissues, including secondary lymphoid tissue chemokine (SLC), EBV-induced molecule 1 ligand chemokine (ELC), and stromal cell-derived factor 1 (SDF-1). The involvement of tonsillar CXCR5(+) T cells in humoral immune responses is suggested by their localization in the mantle and light zone germinal centers of B cell follicles and by the concomitant expression of activation and costimulatory markers, including CD69, HLA-DR, and inducible costimulator (ICOS). Peripheral blood CXCR5(+) T cells also belong to the CD4(+) memory T cell subset but, in contrast to tonsillar cells, are in a resting state and migrate weakly to chemokines. CXCR5(+) T cells are very inefficient in the production of cytokines but potently induce antibody production during coculture with B cells. These properties portray CXCR5(+) T cells as a distinct memory T cell subset with B cell helper function, designated here as follicular B helper T cells (T(FH)).

Follicular B helper T cells express CXC chemokine receptor 5, localize to B cell follicles, and support immunoglobulin production

Chemokines and their receptors have been identified as major regulators controlling the functional organization of secondary lymphoid organs. Here we show that expression of CXC chemokine receptor 5 (CXCR5), a chemokine receptor required for B cell homing to B cell follicles, defines a novel subpopulation of B helper T cells localizing to follicles. In peripheral blood these cells coexpress CD45RO and the T cell homing CC chemokine receptor 7 (CCR7). In secondary lymphoid organs, CD4(+)CXCR5(+) cells lose expression of CCR7, which allows them to localize to B cell follicles and germinal centers where they express high levels of CD40 ligand (CD40L), a costimulatory molecule required for B cell activation and inducible costimulator (ICOS), a recently identified costimulatory molecule of the CD28 family. Thus, when compared with CD4(+)CD45RO(+)CXCR5(-) cells, CD4(+)CD45RO(+)CXCR5(+) tonsillar T cells efficiently support the production of immunoglobulin (Ig)A and IgG. In contrast, analysis of the memory response revealed that long-lasting memory cells are found within the CD4(+)CD45RO(+)CXCR5(-) population, suggesting that CXCR5(+)CD4 cells represent recently activated effector cells. Based on the characteristic localization within secondary lymphoid organs, we suggest to term these cells "follicular B helper T cells" (T(FH)).

Expression of CCR6 and CD83 by cytokine-activated human neutrophils

Polymorphonuclear leukocytes (PMNLs) are thought to be terminally differentiated, short-lived, and unable to actively synthesize new proteins or to interact with T cells. In the current study, it was found that PMNLs incubated with supernatants of phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PHA-sup) expressed high levels of CCR6 mRNA. Neutralization with IgG against several cytokines revealed that tumor necrosis factor (TNF)-alpha was largely responsible for the PHA-sup-induced CCR6 mRNA expression. Among recombinant cytokines, TNF-alpha induced high levels of CCR6 mRNA expression, whereas interferon (IFN)-gamma induced low levels. The 2 cytokines together exhibited a considerable synergy. Cytokine-activated PMNLs expressed functional CCR6, as detected by the binding of sodium iodide I 125-labeled liver and activation-regulated chemokine (LARC) and dose-dependent migration toward LARC. The induction of CCR6 suggested that these cytokine-activated PMNLs have more similarities with dendritic cells (DCs) that express CCR6 in an immature stage. In fact, the activation of PMNLs with TNF-alpha and IFN-gamma induced the expression of CD83, a dominant cell-surface marker of DCs. When PMNLs were activated with granulocyte macrophage-colony-stimulating factor, TNF-alpha, and IFN-gamma, these cells expressed CD40 and HLA-DR in addition to CD83. Taken together, PMNLs, under appropriate conditions, can undergo a differentiation process characterized by the acquisition of new phenotypes and functions, and such differentiated PMNLs may play more active roles in the adaptive immune response. (Blood. 2000;96:3958-3963)

Expression and regulation of regulated on activation, normal T cells expressed and secreted in thyroid tissue of patients with Graves' disease and thyroid autonomy and in thyroid-derived cell populations

Thyroid glands affected by Graves' disease (GD) show striking lymphocytic infiltration, mainly by CD45RO(+) T cells. The mechanisms by which the various lymphocytic subsets are recruited and maintained in the thyroid are unknown. RANTES (regulated on activation, normal T cells expressed and secreted) in interaction with its receptors (CCR1, CCR3, CCR4 and CCR5) may be one of the favorite chemokines involved in the cell trafficking and maintenance. RANTES messenger RNA (mRNA) was quantified in the thyroid tissue of 16 patients with GD and 7 patients with thyroid autonomy (TA), using competitive RT-PCR. We found a clear correlation between the RANTES mRNA level and 1) the degree of T-cell infiltration (r = 0.68), and 2) the level of serum antibodies to thyroid peroxidase (r = 0.76) in GD but not in TA patients. There was no difference between the autonomous nodules and the quiescent surrounding tissue in TA patients. To define the cellular source of RANTES mRNA and protein, we examined various thyroid-derived cells. Lymphocytes showed a markedly higher basal RANTES mRNA and protein level (mean +/- SEM; pg/mL, n = 3; 140 +/- 30) than thyrocytes (12 +/- 5) and fibroblasts (9 +/- 2). Lymphocyte stimulation with PMA enhanced RANTES secretion significantly (4490 +/- 200). Fibroblasts responded to stimulation with interleukin 1 (530 +/- 220) and tumor necrosis factor alpha (2780 +/- 1790), whereas thyrocytes did not. However, some thyroid carcinoma cell lines showed very high basal and stimulated RANTES expression. Lymphocytes expressed the mRNA of all chemokine receptors that bind RANTES. The number of CCR3(+) and CCR5(+) T cells was significantly higher in thyroid-derived leukocytes than in those in the peripheral blood stream. We conclude that RANTES expression, mainly by lymphocytes, is perhaps involved in the maintenance of lymphocytic infiltration and, therefore, in the autoimmune responses in GD.

Bone marrow cells promote TH2 polarization and inhibit virus-specific CTL generation

This laboratory recently reported that human bone marrow cells (BMC) inhibit the generation of virus-specific CTL in culture. The culture supernatants contained increased levels of prostaglandin E(2) (PGE(2)) (shown to favor TH2 cell development) and also inhibited EBV-CTL effector cell development. In this study, we obtained PBL from Epstein-Barr virus (EBV) IgG antibody positive kidney transplant recipients (R) and their living-related donors (LRD) one year after renal transplantation. EBV-specific CTL were then generated in vitro by stimulating PBL with autologous EBV-transformed B cells (EBV-B) in the presence or absence of autologous BMC. The addition of BMC to the EBV-CTL generation cultures increased the intracellular expression in CD3+ cells of IL-4,-5,-6,-10, and -13. These CD3+ cells also expressed increased levels of the TH2 associated receptor CCR3. Inhibition was even observed by preparing EBV-CTL generating cultures in trans-wells that separated the autologous BMC from the PBL + EBV-B. It was then observed that CD3+ cells obtained after 7 days of culture in the presence of autologous BMC could be used as inhibitors of EBV-CTL generation. Protein Kinase A (PKA), a cAMP kinase that is involved in the upregulation of TH2 cytokine activity, was increased in EBV-CTL cultures by the presence of BMC. Additionally, IL-4-mediated signal transduction and activation of transcription (STAT-6) phosphorylation was slightly increased. These results show that the BMC inhibition is mediated by soluble factors (cytokines) and that cell-cell contact in this autologous system is not required, so that BMC (at least partially, via cytokine production) promote TH2 polarization in culture. Moreover, TH2 cells induced by culturing with autologous BMC directly inhibit EBV-CTL generation, and TH2 associated PKA, CCR3, and STAT-6 phosphorylation are enhanced by BMC.

Identification of genes associated with the progression of adult T cell leukemia (ATL)

Patients with adult T-cell leukemia/lymphoma (ATL) exhibit a variety of clinical features, and this disease is therefore clinically subclassified into acute, lymphomatous, chronic, and smoldering types. Acute ATL is a typical leukemic form of ATL with rapid progression, and chronic ATL is a less aggressive clinical form allowing long-term survival even without chemotherapy. In the present study, we used fresh peripheral blood mononuclear cells (PBMC) from both types of ATL patients to identify molecules that may contribute to the difference between acute and chronic ATL. Isolated mRNAs expressed differentially between the two types of ATL include a T-cell differentiation antigen (MAL), a lymphoid-specific member of the G-protein-coupled receptor family (EBI-1 / CCR7), a novel human homologue to a subunit (MNLL) of the bovine ubiquinone oxidoreductase complex, and a human fibrinogen-like protein (hpT49). We found that the former three are upregulated in acute ATL and the last is down-regulated in both chronic and acute ATL. We speculate that dysregulation of the genes may account for the malignant features of ATL cells, in terms of growth, energy metabolism, and motility.

The role of thymus-expressed chemokine and its receptor CCR9 on lymphocytes in the regional specialization of the mucosal immune system

Chemokines play an important role in the migration of leukocytes at sites of inflammation, and some constitutively expressed chemokines may direct lymphocyte trafficking within lymphoid organs and peripheral tissues. Thymus-expressed chemokine (TECK or Ckbeta-15/CCL25), which signals through the chemokine receptor CCR9, is constitutively expressed in the thymus and small intestine but not colon, and chemoattracts a small fraction of PBLs that coexpress the integrin alpha(4)beta(7). Here we show that TECK is expressed in the human small bowel but not colon by endothelial cells and a subset of cells in intestinal crypts and lamina propria. CCR9 is expressed in the majority of freshly isolated small bowel lamina propria mononuclear cells (LPMC) and at significantly higher levels compared with colonic LPMC or PBL. TECK was selectively chemotactic for small bowel but not colonic LPMC in vitro. The TECK-induced chemotaxis was sensitive to pertussis toxin and partially inhibited by Abs to CCR9. TECK attracts predominantly the T cell fraction of small bowel LPMC, whereas sorted CD3(+)CCR9(+) and CD3(+)CCR9(-) lymphocytes produce similar Th1 or Th2 cytokines at the single cell level. Collectively, our data suggest that the selective expression of TECK in the small bowel underlie the homing of CCR9(+) intestinal memory T cells to the small bowel rather than to the colon. This regional specialization implies a segregation of small intestinal from colonic immune responses.

CD30 signals integrate expression of cytotoxic effector molecules, lymphocyte trafficking signals, and signals for proliferation and apoptosis

Although CD30 has long been recognized as an important marker on many lymphomas of diverse origin and as activation molecule on B cells and T cells, its primary function has remained obscure. We now report that CD30 signals may serve to inhibit effector cell activity by integrating gene expression changes of several pathways important for cytotoxic NK and T cell effector function. In the large granular lymphoma line YT, CD30 signals down-regulate the expression of cytotoxic effector molecules, Fas ligand, perforin, granzyme B, and abrogate cytotoxicity. c-myc, a regulator of proliferation and an upstream regulator of Fas ligand expression, is completely suppressed by CD30. Furthermore, CD30 signals strongly induce CCR7, suggesting a role for CD30 signals in the homing of lymphocytes to lymph nodes. The up-regulation of Fas, death receptor 3, and TNF-related apoptosis-inducing ligand by CD30 indicates an increase in susceptibility to apoptotic signals whereas up-regulation of TNFR-associated factor 1 and cellular inhibitor of apoptosis 2 protect cells from certain types of apoptosis. Using gene microarrays, 750 gene products were induced and 90 gene products were suppressed >2-fold by CD30 signals. Signals emanating from CD30 use both TNFR-associated factor 2-dependent and -independent pathways. The integration of CD30 signals in a lymphoma line suggests that CD30 can down-modulate lymphocyte effector function and proliferation while directing the cells to lymph nodes and increasing their susceptibility to certain apoptotic signals. These studies may provide a molecular mechanism for the recently observed CD30-mediated suppression of CTL activity in vivo in a diabetes model.