Inhibition of generation of cytotoxic T lymphocyte activity by a CCL19/macrophage inflammatory protein (MIP)-3beta antagonist

CC Chemokine Family Members' Modulation as a Novel Approach for Treating Central Nervous System and Peripheral Nervous System Injury-A Review of Clinical and Experimental Findings

Despite significant progress in modern medicine and pharmacology, damage to the nervous system with various etiologies still poses a challenge to doctors and scientists. Injuries lead to neuroimmunological changes in the central nervous system (CNS), which may result in both secondary damage and the development of tactile and thermal hypersensitivity. In our review, based on the analysis of many experimental and clinical studies, we indicate that the mechanisms occurring both at the level of the brain after direct damage and at the level of the spinal cord after peripheral nerve damage have a common immunological basis. This suggests that there are opportunities for similar pharmacological therapeutic interventions in the damage of various etiologies. Experimental data indicate that after CNS/PNS damage, the levels of 16 among the 28 CC-family chemokines, i.e., CCL1, CCL2, CCL3, CCL4, CCL5, CCL6, CCL7, CCL8, CCL9, CCL11, CCL12, CCL17, CCL19, CCL20, CCL21, and CCL22, increase in the brain and/or spinal cord and have strong proinflammatory and/or pronociceptive effects. According to the available literature data, further investigation is still needed for understanding the role of the remaining chemokines, especially six of them which were found in humans but not in mice/rats, i.e., CCL13, CCL14, CCL15, CCL16, CCL18, and CCL23. Over the past several years, the results of studies in which available pharmacological tools were used indicated that blocking individual receptors, e.g., CCR1 (J113863 and BX513), CCR2 (RS504393, CCX872, INCB3344, and AZ889), CCR3 (SB328437), CCR4 (C021 and AZD-2098), and CCR5 (maraviroc, AZD-5672, and TAK-220), has beneficial effects after damage to both the CNS and PNS. Recently, experimental data have proved that blockades exerted by double antagonists CCR1/3 (UCB 35625) and CCR2/5 (cenicriviroc) have very good anti-inflammatory and antinociceptive effects. In addition, both single (J113863, RS504393, SB328437, C021, and maraviroc) and dual (cenicriviroc) chemokine receptor antagonists enhanced the analgesic effect of opioid drugs. This review will display the evidence that a multidirectional strategy based on the modulation of neuronal-glial-immune interactions can significantly improve the health of patients after CNS and PNS damage by changing the activity of chemokines belonging to the CC family. Moreover, in the case of pain, the combined administration of such antagonists with opioid drugs could reduce therapeutic doses and minimize the risk of complications.

The multiple roles of chemokines in the mechanisms of stent biocompatibility

While the advent of drug-eluting stents has been clinically effective in substantially reducing the rates of major stent-related adverse events compared with bare metal stents, vascular biological problems such as neointimal hyperplasia, delayed re-endothelialization, late stent thrombosis are not eliminated and, increasingly, neoatherosclerosis is the underlying mechanism for very late stent failure. Further understanding regarding the mechanisms underlying the biological responses to stent deployment is therefore required so that new and improved therapies can be developed. This review will discuss the accumulating evidence that the chemokines, small inflammatory proteins, play a role in each key biological process of stent biocompatibility. It will address the chemokine system in its specialized roles in regulating the multiple facets of vascular biocompatibility including neointimal hyperplasia, endothelial progenitor cell (EPC) mobilization and re-endothelialization after vascular injury, platelet activation and thrombosis, as well as neoatherosclerosis. The evidence in this review suggests that chemokine-targeting strategies may be effective in controlling the pathobiological processes that lead to stent failure. Preclinical studies provide evidence that inhibition of specific chemokines and/or broad-spectrum inhibition of the CC-chemokine class prevents neointimal hyperplasia, reduces thrombosis and suppresses the development of neoatherosclerosis. In contrast, however, to these apparent deleterious effects of chemokines on stent biocompatibility, the CXC chemokine, CXCL12, is essential for the mobilization and recruitment of EPCs that make important contributions to re-endothelialization post-stent deployment. This suggests that future chemokine inhibition strategies would need to be correctly targeted so that all key stent biocompatibility areas could be addressed, without compromising important adaptive biological responses.

CCR7 as a therapeutic target in Cancer

The CCR7 chemokine axis is comprised of chemokine ligand 21 (CCL21) and chemokine ligand 19 (CCL19) acting on chemokine receptor 7 (CCR7). This axis plays two important but apparently opposing roles in cancer. On the one hand, this axis is significantly engaged in the trafficking of a number of effecter cells involved in mounting an immune response to a growing tumour. This suggests therapeutic strategies which involve potentiation of this axis can be used to combat the spread of cancer. On the other hand, the CCR7 axis plays a significant role in controlling the migration of tumour cells towards the lymphatic system and metastasis and can thus contribute to the expansion of cancer. This implies that therapeutic strategies which involve decreasing signaling through the CCR7 axis would have a beneficial effect in preventing dissemination of cancer. This dichotomy has partly been the reason why this axis has not yet been exploited, as other chemokine axes have, as a therapeutic target in cancer. Recent report of a crystal structure for CCR7 provides opportunities to exploit this axis in developing new cancer therapies. However, it remains unclear which of these two strategies, potentiation or antagonism of the CCR7 axis, is more appropriate for cancer therapy. This review brings together the evidence supporting both roles of the CCR7 axis in cancer and examines the future potential of each of the two different therapeutic approaches involving the CCR7 axis in cancer.

Duck hepatitis A virus 1 has lymphoid tissue tropism altering the organic immune responses of mature ducks

Duck hepatitis A virus 1 (DHAV-1) is a highly prevalent pathogen within adult ducks causing acute as well as chronic hepatitis which closely emulates the progression of human hepatitis. However, the underlying mechanisms of DHAV-1 persistence and the pathogenesis of chronic liver disease are not well defined. The association between hematopoietic reservoirs of virus and persistent infection is increasingly concerning. Here, we explored the ability of lymphoid replication of DHAV-1 and the effect on immunity. We found that DHAV-1 was able to infect and replicate productively in the lymphoid organs of model ducks, persisting over 6 months. Moreover, a significant correlation of viral loads between these organs and blood was found, documenting a major contribution of lymphoid replication to DHAV-1 viraemia. Along with viral replication, the mRNA of PRRs and immune-related cytokines was up-regulated in these organs during the early phase of infection, showing tissue-dependent expression patterns but all inclining towards Th2 responses due to the consistently higher level of IL-4 than IL-2 and IFN-γ. Additionally, the expression of CCL19, CCL21, MHC-I and MHC-II, which are involved in T cell homing to the periphery and priming, was dysmodulated. Our data indicate that DHAV-1 possesses lymphoid tissue tropism, contributing to persistent infection and chronic hepatitis via altering the early endogenous transcription of immune-related genes and thereby perturbing organic immunity. These results may be useful to develop novel strategies to treat chronic viral hepatitis based on stimulation of the early innate system and regulation of T-cell trafficking.

Treatment with an immature dendritic cell-targeting vaccine supplemented with IFN-α and an inhibitor of DNA methylation markedly enhances survival in a murine melanoma model

BACKGROUND

The chemokine MIP-3α (CCL20) binds to CCR6 on immature dendritic cells. DNA vaccines fusing MIP-3α to melanoma-associated antigens have shown improved efficacy and immunogenicity in the B16F10 mouse melanoma model. Here, we report that the combination of type-I interferon therapy (IFNα) with 5-Aza-2'-deoxycitidine (5Aza) profoundly enhanced the therapeutic efficacy of a MIP-3α-Gp100-Trp2 DNA vaccine.

METHODS

Beginning on day 5 post-transplantation of B16F10 melanoma, vaccine was administered intramuscularly (i.m.) by electroporation. CpG adjuvant was given 2 days later. 5Aza was given intraperitoneally at 1 mg/kg and IFNα therapy either intratumorally or i.m. as noted. Tumor sizes, tumor growth, and mouse survival were assessed. Tumor lysate gene expression levels and tumor-infiltrating lymphocytes (TILs) were assessed by qRT-PCR and flow cytometry, respectively.

RESULTS

Adding IFNα and 5Aza treatments to mice vaccinated with MIP-3α-Gp100-Trp2 leads to reduced tumor burden and increased median survival (39% over vaccine and 95% over controls). Tumor lysate expression of CCL19 and CCR7 were upregulated ten and fivefold over vaccine, respectively. Vaccine-specific and overall CD8+ TILs were increased over vaccine (sevenfold and fourfold, respectively), as well as the proportion of TILs that were CD8+ (twofold).

CONCLUSIONS

Efficient targeting of antigen to immature dendritic cells with a chemokine-fusion vaccine offers an alternative to classic and dendritic cell vaccines. Combining this approach with IFNα and 5Aza treatment significantly improved vaccine efficacy. This improved efficacy correlated with changes in chemokine gene expression and CD8+ TIL infiltration and was dependent on the presence of all therapeutic components.

Biased signaling of G protein-coupled receptors - From a chemokine receptor CCR7 perspective

Chemokines (chemotactic cytokines) and their associated G protein-coupled receptors (GPCRs) work in a concerted manner to govern immune cell positioning in time and space. Promiscuity of both ligands and receptors, but also biased signaling within the chemokine system, adds to the complexity of how the cell-based immune system is controlled. Bias comes in three forms; ligand-, receptor- and tissue-bias. Biased signaling is increasingly being recognized as playing an important role in contributing to the fine-tuned coordination of immune cell chemotaxis. In the current review we discuss the recent findings related to ligand- and tissue-biased signaling of CCR7 and summarize what is known about bias at other chemokine receptors. CCR7 is expressed by a subset of T-cells and by mature dendritic cells (DCs). Together with its two endogenous ligands CCL19 and CCL21, of which the carboxy terminal tail of CCL21 displays an extraordinarily strong glycosaminoglycan (GAG) binding, CCR7 plays a central role in coordinating the meeting between mature antigen presenting DCs and naïve T-cells which normally takes place in the lymph nodes (LNs). This process is a prerequisite for the initiation of an antigen-specific T-cell mediated immune response. Thus CCR7 and its ligands are key players in initiating cell-based immune responses. CCL19 and CCL21 display differential interaction- and docking-modes for CCR7 leading to stabilization of different CCR7 conformations and hereby preferential activation of distinct intracellular signaling pathways (i.e. ligand bias). In general CCL19 seems to generate a strong temporal signal, whereas CCL21 generates a weaker, but more persistent signal. Tissue differential expression of these two ligands, and the generation of a third ligand "tailless-CCL21", through DC specific protease activity (tissue bias), orchestrates DC and T-cell LN homing and priming, with each ligand serving overlapping, but also distinct roles.

Chemokines and Their Receptors in Islet Allograft Rejection and as Targets for Tolerance Induction

Graft rejection is a major barrier to successful outcome of transplantation surgery. Islet transplantation introduces insulin secreting tissue into type 1 diabetes mellitus recipients, relieving patients from exogenous insulin injection. However, insulitis of grafted tissue and allograft rejection prevent long-term insulin independence. Leukocyte trafficking is necessary for the launch of successful immune responses to pathogen or allograft. Chemokines, small chemotactic cytokines, direct the migration of leukocytes through their interaction with chemokine receptors found on cell surfaces of immune cells. Unique receptor expression of leukocytes, and the specificity of chemokine secretion during various states of immune response, suggest that the extracellular chemokine milieu specifically homes certain leukocyte subsets. Thus, only those leukocytes required for the current immune task are attracted to the inflammatory site. Chemokine blockade, using antagonists and monoclonal antibodies directed against chemokine receptors, is an emerging and specific immunosuppressive strategy. Importantly, chemokine blockade may potentiate tolerance induction regimens to be used following transplantation surgery, and prevent the need for life-long immunosuppression of islet transplant recipients. Here, the role for chemokine blockade in islet transplant rejection and tolerance is reviewed.

Tertiary lymphoid structures, drivers of the anti-tumor responses in human cancers

The characterization of the microenvironment of human tumors led to the description of tertiary lymphoid structures (TLS) characterized by mature dendritic cells in a T-cell zone adjacent to B-cell follicle including a germinal center. TLS represent sites of lymphoid neogenesis that develop in most solid cancers. Analysis of the current literature shows that the TLS presence is associated with a favorable clinical outcome for cancer patients, regardless of the approach used to quantify TLS and the stage of the disease. Using several approaches that combine immunohistochemistry, gene expression assays, and flow cytometry on large series of lung tumors, our work demonstrated that TLS are important sites for the initiation and/or maintenance of the local and systemic T- and B-cell responses against tumors. Surrounded by high endothelial venules, they represent a privileged area for the recruitment of lymphocytes into tumors and generation of central-memory T and B cells that circulate and limit cancer progression. TLS can be considered as a novel biomarker to stratify the overall survival risk of untreated cancer patients and as a marker of efficient immunotherapies. The induction and manipulation of cancer-associated TLS using drug agonists and/or biotherapies should open new avenues to treat cancer patients.

The chemokine receptor CCR7 promotes mammary tumorigenesis through amplification of stem-like cells

The chemokine receptor CCR7 is widely implicated in breast cancer pathobiology. Although recent reports correlated high CCR7 levels with more advanced tumor grade and poor prognosis, limited in vivo data are available regarding its specific function in mammary gland neoplasia and the underlying mechanisms involved. To address these questions we generated a bigenic mouse model of breast cancer combined with CCR7 deletion, which revealed that CCR7 ablation results in a considerable delay in tumor onset as well as significantly reduced tumor burden. Importantly, CCR7 was found to exert its function by regulating mammary cancer stem-like cells in both murine and human tumors. In vivo experiments showed that loss of CCR7 activity either through deletion or pharmacological antagonism significantly decreased functional pools of stem-like cells in mouse primary mammary tumors, providing a mechanistic explanation for the tumor-promoting role of this chemokine receptor. These data characterize the oncogenic properties of CCR7 in mammary epithelial neoplasia and point to a new route for therapeutic intervention to target evasive cancer stem cells.

A myriad of functions and complex regulation of the CCR7/CCL19/CCL21 chemokine axis in the adaptive immune system

The chemokine receptor CCR7 and its ligands CCL19 and CCL21 control a diverse array of migratory events in adaptive immune function. Most prominently, CCR7 promotes homing of T cells and DCs to T cell areas of lymphoid tissues where T cell priming occurs. However, CCR7 and its ligands also contribute to a multitude of adaptive immune functions including thymocyte development, secondary lymphoid organogenesis, high affinity antibody responses, regulatory and memory T cell function, and lymphocyte egress from tissues. In this survey, we summarise the role of CCR7 in adaptive immunity and describe recent progress in understanding how this axis is regulated. In particular we highlight CCX-CKR, which scavenges both CCR7 ligands, and discuss its emerging significance in the immune system.

Intragraft transcriptome level of CXCL9 as biomarker of acute cellular rejection after liver transplantation

BACKGROUND

Liver transplantation has been a life-saving and well-established treatment for acute liver failure and various end-stage liver diseases. However, acute cellular rejection (ACR) is one of the key factors that determine long-term graft function and survival after liver transplantation, and there are still no specific biomarkers available to monitor the alloimmune response. The aim of the present study was to identify molecular biomarkers for ACR in liver allograft.

METHODS

We analyzed the gene expression profile using an oligonucleotide microarray covering 44,000 human probes in 35 liver biopsy samples after living donor liver transplant, which consisted of 13 samples with ACR (ACR group; moderate/mild, 6/7), 13 samples with other dysfunctions (non-ACR group; recurrent hepatitis C / ischemia/reperfusion injury (IRI)/ nonspecific inflammation / small-for-size syndrome, 5/4/3/1), and 9 samples without liver dysfunction (protocol group). We selected 113 informative genes based on microarray results and adopted the network analysis to visualize key modulators in ACR. We selected 6 modulators (CXCL9, GZMB, CCL19, GBP2, LAIR1, and CDC25A) and confirmed the reproducibility in 23 independent biopsy samples and investigated the response to the rejection treatment in sequential samples.

RESULTS

Network analysis revealed the top three subnetworks, which had NF-κB, MAPK, and IFNG as central hubs. Among selected modulators, intragraft expression levels of CXCL9 mRNA was most upregulated and sensitive to alloimmune status.

CONCLUSION

Intragraft CXCL9 mRNA has a functionally important role in T-cell activation in liver allograft and serves as biomarker for ACR.

HIV persistence: chemokines and their signalling pathways

Latently infected resting CD4+ T cells are the major barrier to curing HIV. We have recently demonstrated that chemokines, which bind to the chemokine receptors CCR7, CXCR3 and CCR6, facilitate efficient HIV nuclear localisation and integration in resting CD4+ T cells, leading to latency. As latently infected cells are enriched in lymphoid tissues, where chemokines are highly concentrated, this may provide a mechanism for the generation of latently infected cells in vivo. Here we review the role of chemokines in HIV persistence; the main signalling pathways that are involved; and how these pathways may be exploited to develop novel strategies to reduce or eliminate latently infected cells.

CCR7/CCL19 controls expression of EDG-1 in T cells

T lymphocytes circulate between the blood, tissues, and lymph. These T cells carry out immune functions, using the C-C chemokine receptor 7 (CCR7) and its cognate ligands, CCL19 and CCL21, to enter and travel through the lymph nodes. Distinct roles for each ligand in regulating T lymphocyte trafficking have remained elusive. We report that in the human T cell line HuT78 and in primary murine T lymphocytes, signaling from CCR7/CCL19 leads to increased expression and phosphorylation of extracellular signal-regulated kinase 5 (ERK5) within eight hours of stimulation. Within 48-72 h we observed peak levels of endothelial differentiation gene 1 (EDG-1), which mediates the egress of T lymphocytes from lymph nodes. The increased expression of EDG-1 was preceded by up-regulation of its transcription factor, Krüppel-like factor 2 (KLF-2). To determine the cellular effect of disrupting ERK5 signaling from CCR7, we examined the migration of ERK5(flox/flox)/Lck-Cre murine T cells to EDG-1 ligands. While CCL19-stimulated ERK5(flox/flox) naïve T cells showed increased migration to EDG-1 ligands at 48 h, the migration of ERK5(flox/flox)/Lck-Cre T cells remained at a basal level. Accordingly, we define a novel signaling pathway that controls EDG-1 up-regulation following stimulation of T cells by CCR7/CCL19. This is the first report to link the two signaling events that control migration through the lymph nodes: CCR7 mediates entry into the lymph nodes and EDG-1 signaling controls their subsequent exit.

Early events of HIV-1 infection: can signaling be the next therapeutic target?

Intracellular signaling events are signposts of biological processes, which govern the direction and action of biological activities. Through millions of years of evolution, pathogens, such as viruses, have evolved to hijack host cell machinery to infect their targets and are therefore dependent on host cell signaling for replication. This review will detail our current understanding of the signaling events that are important for the early steps of HIV-1 replication. More specifically, the therapeutic potential of signaling events associated with chemokine coreceptors, virus entry, viral synapses, and post-entry processes will be discussed. We argue that these pathways may represent novel targets for antiviral therapy.

Dynamic modulation of CCR7 expression and function on naive T lymphocytes in vivo

The chemokine receptor CCR7 is critical for the recirculation of naive T cells. It is required for T cell entry into secondary lymphoid organs (SLO) and for T cell motility and retention within these organs. How CCR7 activity is regulated during these processes in vivo is poorly understood. Here we show strong modulation of CCR7 surface expression and occupancy by the two CCR7 ligands, both in vitro and in vivo. In contrast to blood, T cells in SLO had most surface CCR7 occupied with CCL19, presumably leading to continuous signaling and cell motility. Both ligands triggered CCR7 internalization in vivo as shown in Ccl19(-/-) and plt/plt mice. Importantly, CCR7 occupancy and down-regulation led to strongly impaired chemotactic responses, an effect reversible by CCR7 resensitization. Therefore, during their recirculation, T cells cycle between states of free CCR7 with high ligand sensitivity in blood and occupied CCR7 associated with continual signaling and reduced ligand sensitivity within SLO. We propose that these two states of CCR7 are important to allow the various functions CCR7 plays in T cell recirculation.

Arrestin 3 mediates endocytosis of CCR7 following ligation of CCL19 but not CCL21

Internalization of ligand bound G protein-coupled receptors, an important cellular function that mediates receptor desensitization, takes place via distinct pathways, which are often unique for each receptor. The C-C chemokine receptor (CCR7) G protein-coupled receptor is expressed on naive T cells, dendritic cells, and NK cells and has two endogenous ligands, CCL19 and CCL21. Following binding of CCL21, 21 +/- 4% of CCR7 is internalized in the HuT 78 human T cell lymphoma line, while 76 +/- 8% of CCR7 is internalized upon binding to CCL19. To determine whether arrestins mediated differential internalization of CCR7/CCL19 vs CCR7/CCL21, we used small interfering RNA (siRNA) to knock down expression of arrestin 2 or arrestin 3 in HuT 78 cells. Independent of arrestin 2 or arrestin 3 expression, CCR7/CCL21 internalized. In contrast, following depletion of arrestin 3, CCR7/CCL19 failed to internalize. To examine the consequence of complete loss of both arrestin 2 and arrestin 3 on CCL19/CCR7 internalization, we examined CCR7 internalization in arrestin 2(-/-)/arrestin 3(-/-) murine embryonic fibroblasts. Only reconstitution with arrestin 3-GFP but not arrestin 2-GFP rescued internalization of CCR7/CCL19. Loss of arrestin 2 or arrestin 3 blocked migration to CCL19 but had no effect on migration to CCL21. Using immunofluorescence microscopy, we found that arrestins do not cluster at the membrane with CCR7 following ligand binding but cap with CCR7 during receptor internalization. These are the first studies that define a role for arrestin 3 in the internalization of a chemokine receptor following binding of one but not both endogenous ligands.

Autocrine and paracrine chemokine receptor 7 activation in head and neck cancer: implications for therapy

BACKGROUND

The chemokine receptor 7 (CCR7) mediates survival and invasiveness of metastatic squamous cell carcinoma of the head and neck (SCCHN) to regional lymph nodes. Constitutive prosurvival signaling by the phosphoinositide-3 kinase/Akt pathway has been observed in SCCHN cells independent of epidermal growth factor receptor (EGFR) signaling.

METHODS

Human SCCHN cell lines were treated with agents that block or activate CCR7-mediated signaling, and Akt activation, cell viability in the presence or absence of EGFR inhibition, and cisplatin-induced apoptosis (in the presence or absence of Akt inhibition) were assessed by immunoblotting, the MTT assay, and the detection of annexin V, respectively. Expression and secretion of chemokines by primary tumors, metastatic nodes, and benign nodes of patients with SCCHN were determined by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The role of paracrine activation of CCR7 on tumor growth was analyzed by comparing the growth of orthotopic tumors derived from B7E3 murine oral carcinoma cells in wild-type BALB/c mice, in paucity of lymphoid T cell (plt, deficient in CCL19 and CCL21 expression) mice, and in plt mice in which the implanted B7E3 cells overexpressed CCR7 (n = 14 mice per group).

RESULTS

In the absence of exogenous ligand treatment, blockade of CCR7 signaling reduced levels of phosphorylated (activated) Akt and decreased SCCHN cell viability by up to 59% (95% confidence interval [CI] = 58.2% to 59.8%), enhancing the effect of EGFR inhibition. CCR7 stimulation protected metastatic SCCHN cells from cisplatin-induced apoptosis in an Akt-dependent manner. Metastatic nodes expressed and secreted higher levels of CCL19 than benign nodes or primary tumors. CCR7-positive murine SCCHN tumors grew more slowly in plt mice than in control BALB/c mice (mean average tumor volume on day 20 = 12.2 and 26.5 mm(3), respectively; difference = 14.3 mm(3), 95% CI = 12.3 to 17.1 mm(3)).

CONCLUSIONS

Secretion of CCL19 and CCL21 by SCCHN cells and by paracrine sources combine to promote activation of CCR7 prosurvival signaling associated with tumor progression and disease relapse. CCR7 and its cognate chemokines may be useful biomarkers of SCCHN progression, and blockade of CCR7-mediated signaling may enhance the efficacy of platinum- and EGFR-based therapies.

Expression of CC chemokine receptor 7 in tonsillar cancer predicts cervical nodal metastasis, systemic relapse and survival

The aim of this study was to evaluate the expression of CC chemokine receptor 7 (CCR7) in squamous cell cancer of the tonsil with respect to patterns of spread, relapse-free, overall and disease-specific survival. Eighty-four patients with squamous cell cancer of the tonsil were identified. There was a male predominance of 3 : 1 and the median age at diagnosis was 53 (range 35–86) years. The median duration of follow-up was 33 (range 2–124) months. There was a significant association between CCR7 immunopositivity and synchronous cervical nodal metastasis in patients with tonsillar cancer (Spearman's correlation coefficient 0.564; P<0.001). Relapse-free (P=0.0175), overall (P=0.0136) and disease-specific (P=0.0062) survival rates were significantly lower in patients whose tumours expressed high levels of CCR7. On multivariate analysis, high-level CCR7 staining predicted relapse-free (hazard ratio 3.0, 95% confidence intervals 1.1–8.0, P=0.026) and disease-specific (hazard ratio 10.2, 95% confidence intervals 2.1–48.6, P=0.004) survival. Fifteen percent of patients with the highest level of tumour CCR7 immunopositivity relapsed with systemic metastases. These data demonstrated that CCR7 expression was associated with cervical nodal and systemic metastases from tonsillar cancers. High levels of CCR7 expression predicted a poor prognosis.

Interaction of the selectin ligand PSGL-1 with chemokines CCL21 and CCL19 facilitates efficient homing of T cells to secondary lymphoid organs

P-selectin glycoprotein ligand 1 (PSGL-1) is central to the trafficking of immune effector cells to areas of inflammation through direct interactions with P-selectin, E-selectin and L-selectin. Here we show that PSGL-1 was also required for efficient homing of resting T cells to secondary lymphoid organs but functioned independently of selectin binding. PSGL-1 mediated an enhanced chemotactic T cell response to the secondary lymphoid organ chemokines CCL21 and CCL19 but not to CXCL12 or to inflammatory chemokines. Our data show involvement of PSGL-1 in facilitating the entry of T cells into secondary lymphoid organs, thereby demonstrating the bifunctional nature of this molecule.

Enhanced Expression of the Homeostatic Chemokines CCL19 and CCL21 in Clinical and Experimental Atherosclerosis

Objective— Based on their role in T-cell homing into nonlymphoid tissue, we examined the role of the homeostatic chemokines CCL19 and CCL21 and their common receptor CCR7 in coronary artery disease (CAD).

Methods and Results— We performed studies in patients with stable (n=40) and unstable (n=40) angina and healthy controls (n=20), in vitro studies in T-cells and macrophages, and studies in apolipoprotein-E–deficient (ApoE −/− ) mice and human atherosclerotic carotid plaques. We found increased levels of CCL19 and CCL21 within the atherosclerotic lesions of the ApoE −/− mice, in human atherosclerotic carotid plaques, and in plasma of CAD patients. Whereas strong CCR7 expression was seen in T-cells from murine and human atherosclerotic plaques, circulating T-cells from angina patients showed decreased CCR7 expression. CCL19 and CCL21 promoted an inflammatory phenotype in T-cells and macrophages and increased matrix metalloproteinase (MMP) and tissue factor levels in the latter cell type. Although aggressive statin therapy increased CCR7 and decreased CCL19/CCL21 levels in peripheral blood from CAD patients, conventional therapy did not.

Conclusions— The abnormal regulation of CCL19 and CCL21 and their common receptor in atherosclerosis could contribute to disease progression by recruiting T-cells and macrophages to the atherosclerotic lesions and by promoting inflammatory responses in these cells.

The Multiple Personalities of the Chemokine Receptor CCR7 in Dendritic Cells

CCR7 was described initially as a potent leukocyte chemotactic receptor that was later shown to be responsible of directing the migration of dendritic cells (DCs) to the lymph nodes where these cells play an important role in the initiation of the immune response. Recently, a variety of reports have indicated that, apart from chemotaxis, CCR7 controls the cytoarchitecture, the rate of endocytosis, the survival, the migratory speed, and the maturation of the DCs. Some of these functions of CCR7 and additional ones also have been described in other cell types. Herein we discuss how this receptor may contribute to modulate the immune response by regulating different functions in DCs. Finally, we also suggest a possible mechanism whereby CCR7 may control its multiple tasks in these cells.

Chemokine receptor 7 activates phosphoinositide-3 kinase-mediated invasive and prosurvival pathways in head and neck cancer cells independent of EGFR

Chemokine receptor 7 (CCR7) upregulation, which mediates immune cell survival and migration to lymph nodes, has recently been associated with nodal metastasis of squamous cell carcinoma of the head and neck (SCCHN). However, the mechanism of CCR7 in tumor progression, its downstream signaling mediators, and interactions with other pathways contributing to metastasis of SCCHN have not been determined. We hypothesized that inflammatory chemokine-mediated signals could also promote tumor proliferation and mitogenic effects. Functional assays showed that chemotaxis and invasion of metastatic SCCHN cells were dependent on phosphoinositide-3 kinase (PI3K) and its substrate, activated phospholipase Cgamma-1. In addition, treatment of CCR7(+) metastatic SCCHN cells with CCL19 (MIP-3beta) showed rapid activation of the prosurvival, PI3K/Akt pathway. Transactivation of EGFR-mediated and mitogen-activated protein kinase signaling pathways, which can promote migration and survival in parallel, did not appear to contribute to the functional or biochemical effects of CCR7 stimulation. Thus, proinflammatory chemokine signals that mediate activation, trafficking and survival of tumor-infiltrating immune cells in the tumor microenvironment actually appear to induce signals for progression of cancer cells. The CCR7-mediated pathway in metastatic SCCHN cells functions independently of EGFR signal transduction and therefore may represent an additional target for therapeutic intervention to prevent tumor progression and metastasis.

Dendritic-cell trafficking to lymph nodes through lymphatic vessels

Antigen-presenting dendritic cells often acquire foreign antigens in peripheral tissues such as the skin. Optimal encounter with naive T cells for the presentation of these antigens requires that the dendritic cells migrate to draining lymph nodes through lymphatic vessels. In this article, we review important aspects of what is known about dendritic-cell trafficking into and through lymphatic vessels to lymph nodes. We present these findings in the context of information about lymphatic-vessel biology. Gaining a better understanding of the crosstalk between dendritic cells and lymphatic vessels during the migration of dendritic cells to lymph nodes is essential for future advances in manipulating dendritic-cell migration as a means to fine-tune immune responses in clinical settings.

CC Chemokine Ligand 19 Secreted by Mature Dendritic Cells Increases Naive T Cell Scanning Behavior and Their Response to Rare Cognate Antigen

For immune responses to take place, naive T cells have to encounter, adhere to, and be stimulated by dendritic cells (DCs). In murine lymph nodes, T cells move randomly and scan the surface of multiple DCs. The factors controlling this motility as well as its consequences remain unclear. We have monitored by video-imaging the earliest steps of the interaction between human DCs and autologous naive CD4+ T cells in the absence of exogenous Ags. Mature, but not immature, DCs were able to elicit small calcium responses in naive T cells along with cell polarization and random motility, resulting in an efficient scanning of DC surfaces by T cells. We identified CCL19 as a key factor enabling all these early T cell responses, including the occurrence of calcium transients. Because this chemokine did not influence the strength of naive T cell adhesion to DCs, enhanced LFA-1 affinity for ICAM-1 was not the main mechanism by which CCL19 increased Ag-independent calcium transients. However, concomitantly to T cell motility, CCL19 augmented the frequency of T cell responses to rare anti-CD3/CD28-coated beads, used as surrogate APCs. We thus propose a new role for CCL19 in humans: by conditioning T cells into a motile DC-scanning state, this chemokine promotes Ag-independent responses and increases the probability of cognate MHC-peptide encounter.