EBI1-ligand chemokine (ELC) attracts a broad spectrum of lymphocytes: activated T cells strongly up-regulate CCR7 and efficiently migrate toward ELC

The Role of Chemokines in Orchestrating the Immune Response to Pancreatic Ductal Adenocarcinoma

Chemokines are small molecules that function as chemotactic factors which regulate the migration, infiltration, and accumulation of immune cells. Here, we comprehensively assess the structural and functional role of chemokines, examine the effects of chemokines that are present in the pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment (TME), specifically those produced by cancer cells and stromal components, and evaluate their impact on immune cell trafficking, both in promoting and suppressing anti-tumor responses. We further explore the impact of chemokines on patient outcomes in PDAC and their role in the context of immunotherapy treatments, and review clinical trials that have targeted chemokine receptors and ligands in the treatment of PDAC. Lastly, we highlight potential strategies that can be utilized to harness chemokines in order to increase cytotoxic immune cell infiltration and the anti-tumor effects of immunotherapy.

Chemokine- and chemokine receptor-based signature predicts immunotherapy response in female colorectal adenocarcinoma patients

The clinical significance and comprehensive characteristics of chemokines and chemokine receptors in female patients with advanced colorectal adenocarcinoma have not ever been reported. Our study explored the expression profiles of chemokines and chemokine receptors and constructed a chemokine- and chemokine receptor-based signature in female patients with advanced colorectal adenocarcinoma. Four independent cohorts containing 1335 patients were enrolled in our study. Univariate Cox regression and least absolute shrinkage and selection operator (LASSO) analyses were performed to construct the signature. CIBERSORT was used to evaluate the landscape of immune cell infiltration. Thirty-two pairs of tissue specimens of female advanced colorectal cancer (CRC) patients and two CRC cell lines were used to validate the signature in vitro. Quantitative real-time PCR and western blotting were performed to validate the mRNA and protein expression levels of signature genes. EdU and colony formation assays were performed to examine proliferative ability. Transwell and wound healing assays were used to evaluate cell invasion and migration capacity. During the signature construction and validation process, we found that the signature was more applicable to female patients with advanced colorectal adenocarcinoma. Hence, the subsequent study mainly focused on the particular subgroup. Enrichment analyses revealed that the signature was closely related to immunity. The landscape of immune cell infiltration presented that the signature was significantly associated with T cells CD8 and neutrophils. Gene set enrichment analysis (GSEA) confirmed that the high-risk group was chiefly enriched in the tumor-promoting related pathways and biological processes, whereas the low-risk group was mainly enriched in anti-tumor immune response pathways and biological processes. The signature was closely correlated with CTLA4, PDL1, PDL2, TMB, MSI, and TIDE, indicating that our signature could serve as a robust biomarker for immunotherapy and chemotherapy response. ROC curves verified that our signature had more robust prognostic power than all immune checkpoints and immunotherapy-related biomarkers. Finally, we used 32 pairs of tissue specimens and 2 CRC cell lines to validate our signature in vitro. We first provided a robust prognostic chemokine- and chemokine receptor-based signature, which could serve as a novel biomarker for immunotherapy and chemotherapy response to guide individualized treatment for female patients with advanced colorectal adenocarcinoma.

Arming CAR-T cells with cytokines and more: Innovations in the fourth-generation CAR-T development

Chimeric antigen receptor T cells (CAR-T) therapy has shown great potential in tumor treatment. However, many factors impair the efficacy of CAR-T therapy, such as antigenic heterogeneity and loss, limited potency and persistence, poor infiltration capacity, and a suppressive tumor microenvironment. To overcome these obstacles, recent studies have reported a new generation of CAR-T cells expressing cytokines called armored CAR-T, TRUCK-T, or the fourth-generation CAR-T. Here we summarize the strategies of arming CAR-T cells with natural or synthetic cytokine signals to enhance their anti-tumor capacity. Moreover, we summarize the advances in CAR-T cells expressing non-cytokine proteins, such as membrane receptors, antibodies, enzymes, co-stimulatory molecules, and transcriptional factors. Furthermore, we discuss several prospective strategies for armored CAR-T therapy development. Altogether, these ideas may provide new insights for the innovations of the next-generation CAR-T therapy.

LIGHT/TNFSF14 promotes CAR-T cell trafficking and cytotoxicity through reversing immunosuppressive tumor microenvironment

Tertiary lymphoid structures (TLSs) in tumor tissues facilitate immune cell trafficking and cytotoxicity, which benefits survival and favorable responses in immune therapy. Here, we observed a high correlation of tumor necrosis factor superfamily member 14 (LIGHT) expression with TLS signature genes, which are all markers for immune cell accumulation and better prognosis, through retrieving RNA sequencing (RNA-seq) data from patients with cancer, suggesting the potential of LIGHT in reconstituting a high immune-infiltrated tumor microenvironment. Accordingly, LIGHT co-expressed chimeric antigen receptor T (LIGHT CAR-T) cells not only showed enhanced cytotoxicity and cytokine production but also improved CCL19 and CCL21 expression by surrounding cells. And the supernatant of LIGHT CAR-T cells promoted T cell migration in a paracrine manner. Furthermore, LIGHT CAR-T cells showed superior anti-tumor efficacy and improved infiltration in comparison with conventional CAR-T cells in immunodeficient NSG mice. Accordingly, murine LIGHT-OT-1 T cells normalized tumor blood vessels and enforced intratumoral lymphoid structures in C57BL/6 syngeneic tumor mouse models, implying the potential of LIGHT CAR-T in clinical application. Taken together, our data revealed a straightforward strategy to optimize trafficking and cytotoxicity of CAR-T cells by redirecting TLSs through LIGHT expression, which has great potential to expand and optimize the application of CAR-T therapy in solid tumors.

Recent Advances in Solid Tumor CAR-T Cell Therapy: Driving Tumor Cells From Hero to Zero?

Chimeric antigen receptor T-cells (CAR-Ts) are known as revolutionary living drugs that have turned the tables of conventional cancer treatments in certain hematologic malignancies such as B-cell acute lymphoblastic leukemia (B-ALL) and diffuse large B-cell lymphoma (DLBCL) by achieving US Food and Drug Administration (FDA) approval based on their successful clinical outcomes. However, this type of therapy has not seen the light of victory in the fight against solid tumors because of various restricting caveats including heterogeneous tumor antigen expression and the immunosuppressive tumor microenvironments (TME) that negatively affect the tumor-site accessibility, infiltration, stimulation, activation, and persistence of CAR-Ts. In this review, we explore strategic twists including boosting vaccines and designing implementations that can support CAR-T expansion, proliferation, and tumoricidal capacity. We also step further by underscoring novel strategies for triggering endogenous antitumor responses and overcoming the limitation of poor CAR-T tumor-tissue infiltration and the lack of definitive tumor-specific antigens. Ultimately, we highlight how these approaches can address the mentioned arduous hurdles.

A novel multimeric sCD19-streptavidin fusion protein for functional detection and selective expansion of CD19-targeted CAR-T cells

Background

CARs are engineered receptors comprising an immunoglobulin single‐chain variable fragment (scFv) that identifies and binds to the target antigen, a transmembrane domain, and an intracellular T‐cell signaling domain. CD19 is a B lineage‐specific transmembrane glycoprotein and is expressed in more than 95% of B‐cell malignancies. Streptavidin (SA) is a homo‐tetrameric protein derived from Streptomyces avidinii, which can bind four biotin molecules with an extremely high affinity at a Kd value of 10^‐15 M.

Aims

The aim of the study is to generate a novel soluble multimeric fusion protein, sCD19‐streptavidin (sCD19‐SA) for functional detection and selective expansion of CD19‐targeted CAR‐T cells.

Methods

The fusion proteins CD19‐SA was expressed in CHO cells and purified by use of Ni‐nitrilotriacetic acid agarose beads.

Results

A novel fusion protein (sCD19‐SA) was generated, consisting of the extracellular domain of human CD19 and the core region of SA, and could be used to functionally detect CD19‐targeted CAR‐T cells. Furthermore, this protein was demonstrated to form multimers to activate CAR‐T cells to induce their selective expansion. Importantly, sCD19‐SA‐stimulated CD19‐targeted CAR‐T cells could improve antitumor effects in vivo.

Conclusions

Our study has highlighted the potential of utilizing antigen‐SA fusion proteins such as sCD19‐SA for CAR‐T therapy for the functional detection of CAR expression and selective expansion of CAR‐T cells.

CCL19 has potential to be a potential prognostic biomarker and a modulator of tumor immune microenvironment (TIME) of breast cancer: a comprehensive analysis based on TCGA database

The development of cancer was determined by not only the intrinsic properties of cancer cells, but also the communication between cancer cells and tumor microenvironment (TME). We applied ESTIMATE and CIBERSORT algorithms to calculate the immune/stromal component and tumor-infiltrating immune cells (TICs) in TME of BC. The results showed that immune component in TME predicted patients’ survival and associated with progression of BC. Differentially expressed genes (DEGs) were primarily enriched in immune-related activities. Finally, CCL19 was acquired which shared the leading nodes in PPI network and was associated with patients’ survival. High expression of CCL19 predicted better prognosis and participated in progression of BC. Genes in CCL19 up-regulated group were enriched in immune-related activities and these functions might depend on the communications between CCL19 and multiple TICs in TIME. In conclusion, CCL19 functioned as a potential prognostic biomarker and a modulator of TIME in BC through communicating with various TICs.

Folate Receptor-Alpha Targeted 7x19 CAR-γδT Suppressed Triple-Negative Breast Cancer Xenograft Model in Mice

Background

Triple-negative breast cancer (TNBC) is the worst prognosis subtype of breast cancer due to lack of specific targets. Recent studies have shown that immunotherapy may solve that problem by targeting folate receptor-alpha (FRα).

Methods

Gene modified γδ T cells were manufactured to express FRa specific chimeric antigen receptor (FRa CAR) and secrete interleukin-7 (IL-7) and chemokine C–C motif ligand 19 (CCL19). CAR-γδT cells that secrete IL-7 and CCL19 (7 × 19 CAR-γδT) were evaluated for their antitumor activity both in vitro and in vivo.

Results

7 × 19 CAR-γδT showed remarkable antitumor activity in vitro. Combined with PBMC, 7 × 19 CAR-γδT inhibited TNBC xenograft model growth superiorly compared with single-application or conventional CAR-γδT cells. Histopathological analyses showed increased DC or T cells infiltration to tumor tissues.

Conclusion

Taken together, our results showed that 7 × 19 CAR-γδT have remarkable anti-TNBC tumor activity and showed a broad application prospect in the treatment of incurable TNBC patients.

C-C Chemokine Receptor 7 in Cancer

C-C chemokine receptor 7 (CCR7) was one of the first two chemokine receptors that were found to be upregulated in breast cancers. Chemokine receptors promote chemotaxis of cells and tissue organization. Since under homeostatic conditions, CCR7 promotes migration of immune cells to lymph nodes, questions immediately arose regarding the ability of CCR7 to direct migration of cancer cells to lymph nodes. The literature since 2000 was examined to determine to what extent the expression of CCR7 in malignant tumors promoted migration to the lymph nodes. The data indicated that in different cancers, CCR7 plays distinct roles in directing cells to lymph nodes, the skin or to the central nervous system. In certain tumors, it may even serve a protective role. Future studies should focus on defining mechanisms that differentially regulate the unfavorable or beneficial role that CCR7 plays in cancer pathophysiology, to be able to improve outcomes in patients who harbor CCR7-positive cancers.

A seven-gene signature and the C-C motif chemokine receptor family genes are the sarcoma-related immune genes

Cells of the tumor microenvironment exert a vital influence on sarcoma prognosis. This study aimed to analyze and identify differentially expressed genes (DEGs) related to immunity and their significance as immune biomarkers for the accurate prediction of overall survival of patients with sarcoma. The Cancer Genome Atlas was adopted for obtaining sarcoma gene microarray and corresponding clinical information. ESTIMATE algorithm was used to calculate tumor immune microenvironment indices. Immune-associated DEGs were identified using the limma packages and were further analyzed using the ClusterProfiler package and STRING website. Based on the results of these analyses, we constructed a prognostic model. Furthermore, we assessed the prognosis prediction model through functional evaluation and analysis of GSE17674. The functional analysis revealed that the upregulated immune DEGs were related to immune-related aspects. Chemokine ligands/receptors and immune-related genes were found to be vital for sarcoma formation and progression. We established a prognostic signature of seven genes, which indicated that high-risk cases exhibit poor prognostic outcome. The prognostic signature constructed in this study can accurately predict the overall prognosis in patients with sarcoma. Moreover, the novel immune gene expression analysis may provide clinical guidance for predicting prognosis in patients with sarcoma.

Local injection of CCL19-expressing mesenchymal stem cells augments the therapeutic efficacy of anti-PD-L1 antibody by promoting infiltration of immune cells

Background

Mesenchymal stem/stromal cells (MSC) accumulate and reside in tumor sites.

Methods

Taking advantage of this feature in anticancer therapy, immortalized murine MSC (iMSC) were genetically altered to produce chemokine (C-C motif) ligand 19 (iMSC/CCL19), which attracts dendritic cells (DC) and T lymphocytes. Thereafter, iMSC/CCL19 were examined for their therapeutic efficacy using a syngeneic CT26 colon carcinoma cell line.

Results

Co-injection of iMSC/CCL19 into mice significantly suppressed the in vivo growth of CT26 cells compared with that of CCL19-expressing immortalized fibroblasts (iFib/CCL19). This anticancer effect was not observed when injected in CT26-bearing nude mice. Co-injected iMSC/CCL19 survived longer than iFib/CCL19 in the tumor sites. In a therapeutic model, local injection of iMSC/CCL19 suppressed the tumor growth, and increased IFN (interferon)-γ⁺ CD8⁺ T cells and CCR7⁺ DC infiltration in tumor site was observed when treated with iMSC/CCL19, but not with iMSC. This antitumor effect was completely negated by depletion of CD4⁺ cells and partially negated by depletion of CD8⁺ cells. Furthermore, the antitumor effects induced by local injection of iMSC/CCL19 were augmented by additional therapy with anti-programmed death (PD)-ligand 1 (PD-L1) antibody, but not with anti-PD-1 antibody. This combination therapy cured most of the tumors in CT26-bearing mice.

Conclusion

These results suggest that local therapy with iMSC/CCL19 can suppress tumor growth via effective recruitment of CCR7⁺ DC into tumor sites and increase IFN-γ⁺ CD8⁺ T cells, and that combination with anti-PD-L1 antibody therapy can be a powerful anticancer therapy.

The BCMA-Targeted Fourth-Generation CAR-T Cells Secreting IL-7 and CCL19 for Therapy of Refractory/Recurrent Multiple Myeloma

Chimeric antigen receptor (CAR) technology has revolutionized cancer treatment, particularly in malignant hematological tumors. Currently, the BCMA-targeted second-generation CAR-T cells have showed impressive efficacy in the treatment of refractory/relapsed multiple myeloma (R/R MM), but up to 50% relapse remains to be addressed urgently. Here we constructed the BCMA-targeted fourth-generation CAR-T cells expressing IL-7 and CCL19 (i.e., BCMA-7 × 19 CAR-T cells), and demonstrated that BCMA-7 × 19 CAR-T cells exhibited superior expansion, differentiation, migration and cytotoxicity. Furthermore, we have been carrying out the first-in-human clinical trial for therapy of R/R MM by use of BCMA-7 × 19 CAR-T cells (ClinicalTrials.gov Identifier: NCT03778346), which preliminarily showed promising safety and efficacy in first two enrolled patients. The two patients achieved a CR and VGPR with Grade 1 cytokine release syndrome only 1 month after one dose of CAR-T cell infusion, and the responses lasted more than 12-month. Taken together, BCMA-7 × 19 CAR-T cells were safe and effective against refractory/relapsed multiple myeloma and thus warranted further clinical study.

CC Chemokines in a Tumor: A Review of Pro-Cancer and Anti-Cancer Properties of Receptors CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10 Ligands

CC chemokines (or β-chemokines) are 28 chemotactic cytokines with an N-terminal CC domain that play an important role in immune system cells, such as CD4⁺ and CD8⁺ lymphocytes, dendritic cells, eosinophils, macrophages, monocytes, and NK cells, as well in neoplasia. In this review, we discuss human CC motif chemokine ligands: CCL1, CCL3, CCL4, CCL5, CCL18, CCL19, CCL20, CCL21, CCL25, CCL27, and CCL28 (CC motif chemokine receptor CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10 ligands). We present their functioning in human physiology and in neoplasia, including their role in the proliferation, apoptosis resistance, drug resistance, migration, and invasion of cancer cells. We discuss the significance of chemokine receptors in organ-specific metastasis, as well as the influence of each chemokine on the recruitment of various cells to the tumor niche, such as cancer-associated fibroblasts (CAF), Kupffer cells, myeloid-derived suppressor cells (MDSC), osteoclasts, tumor-associated macrophages (TAM), tumor-infiltrating lymphocytes (TIL), and regulatory T cells (T_reg). Finally, we show how the effect of the chemokines on vascular endothelial cells and lymphatic endothelial cells leads to angiogenesis and lymphangiogenesis.

MicroRNAs in breast cancer: New maestros defining the melody

MicroRNAs, short non-coding single-stranded RNAs, are important regulators and gatekeepers of the coding genes in the human genome. MicroRNAs are highly conserved among species and expressed in different tissues and cell types. They are involved in almost all the biological processes as apoptosis, proliferation, cell cycle arrest and differentiation. Playing all these roles, it is not surprising that the deregulation of the microRNA profile causes a number of diseases including cancer. Breast cancer, the most commonly diagnosed malignancy in women, accounts for the highest cancer-related deaths worldwide. Different microRNAs were shown to be up or down regulated in breast cancer. MicroRNAs can function as oncogenes or tumor suppressors according to their targets. In this review, the most common microRNAs implicated in breast cancer are fully illustrated with their targets. Besides, the review highlights the effect of exosomal microRNA on breast cancer and the effect of microRNAs on drug and therapies resistance as well as the miRNA-based therapeutic strategies used until today.

Hypoxia Alters the Expression of CC Chemokines and CC Chemokine Receptors in a Tumor-A Literature Review

Hypoxia, i.e., oxygen deficiency condition, is one of the most important factors promoting the growth of tumors. Since its effect on the chemokine system is crucial in understanding the changes in the recruitment of cells to a tumor niche, in this review we have gathered all the available data about the impact of hypoxia on β chemokines. In the introduction, we present the chronic (continuous, non-interrupted) and cycling (intermittent, transient) hypoxia together with the mechanisms of activation of hypoxia inducible factors (HIF-1 and HIF-2) and NF-κB. Then we describe the effect of hypoxia on the expression of chemokines with the CC motif: CCL1, CCL2, CCL3, CCL4, CCL5, CCL7, CCL8, CCL11, CCL13, CCL15, CCL16, CCL17, CCL18, CCL19, CCL20, CCL21, CCL22, CCL24, CCL25, CCL26, CCL27, CCL28 together with CC chemokine receptors: CCR1, CCR2, CCR3, CCR4, CCR5, CCR6, CCR7, CCR8, CCR9, and CCR10. To better understand the effect of hypoxia on neoplastic processes and changes in the expression of the described proteins, we summarize the available data in a table which shows the effect of individual chemokines on angiogenesis, lymphangiogenesis, and recruitment of eosinophils, myeloid-derived suppressor cells (MDSC), regulatory T cells (T_reg), and tumor-associated macrophages (TAM) to a tumor niche.

IL-7 and CCL19 expression in CAR-T cells improves immune cell infiltration and CAR-T cell survival in the tumor

Infiltration, accumulation, and survival of chimeric antigen receptor T (CAR-T) cells in solid tumors is crucial for tumor clearance. We engineered CAR-T cells to express interleukin (IL)-7 and CCL19 (7 × 19 CAR-T cells), as these factors are essential for the maintenance of T-cell zones in lymphoid organs. In mice, 7 × 19 CAR-T cells achieved complete regression of pre-established solid tumors and prolonged mouse survival, with superior anti-tumor activity compared to conventional CAR-T cells. Histopathological analyses showed increased infiltration of dendritic cells (DC) and T cells into tumor tissues following 7 × 19 CAR-T cell therapy. Depletion of recipient T cells before 7 × 19 CAR-T cell administration dampened the therapeutic effects of 7 × 19 CAR-T cell treatment, suggesting that CAR-T cells and recipient immune cells collaborated to exert anti-tumor activity. Following treatment of mice with 7 × 19 CAR-T cells, both recipient conventional T cells and administered CAR-T cells generated memory responses against tumors.

Role of let-7 family microRNA in breast cancer

Metastasis and resistance to therapy significantly contribute to cancer-related deaths. Growing body of evidence suggest that altered expression of microRNAs (miRNAs) is one of the root cause of adverse clinical outcome. miRNAs such as let-7 are the new fine tuners of signaling cascade and cellular processes which regulates the genes in post-transcriptional manner. In this review, we described the regulation of let-7 expression and the involvement of molecular factors in this process. We discussed the mechanism by which let-7 alter the expression of genes involved in the process of tumorigenesis. Further, we listed the pathways targeted by let-7 to reduce the burden of the tumor. In addition, we described the role of let-7 in breast cancer metastasis and stemness properties. This article will provide the in-depth insight into the biology of let-7 miRNA and its role in the breast cancer progression.

Effect of adhesion and chemokine presentation on T-lymphocyte haptokinesis

Motility is critical for the function of T-lymphocytes. Motility in T-lymphocytes is driven by the occupancy of chemokine receptors by chemokines, and modulated by adhesive interactions. However, it is not well understood how the combination of adhesion and chemokine binding affects T-lymphocyte migration. We used microcontact printing on polymeric substrates to measure how lymphocyte migration is quantitatively controlled by adhesion and chemokine ligation. Focusing only on random motion, we found that T-lymphocytes exhibit biphasic motility in response to the substrate concentration of either ICAM-1 or VCAM-1, and generally display more active motion on ICAM-1 surfaces. Furthermore, we examined how the combination of the homeostatic chemokines CCL19 and CCL21 contribute to motility. By themselves, CCL19 and CCL21, ligands for CCR7, elicit biphasic motility, but their combination synergistically increases CCR7 mediated chemokinesis on ICAM-1. By presenting CCL21 with ICAM-1 on the surface with soluble CCL19, we observed random motion that is greater than what is observed with soluble chemokines alone. These data suggest that ICAM-1 has a greater contribution to motility than VCAM-1 and that both adhesive interactions and chemokine ligation work in concert to control T-lymphocyte motility.

The HIV-1 Gp120/CXCR4 axis promotes CCR7 ligand-dependent CD4 T cell migration: CCR7 homo- and CCR7/CXCR4 hetero-oligomer formation as a possible mechanism for up-regulation of functional CCR7

During human immunodeficiency virus (HIV) infection, enhanced migration of infected cells to lymph nodes leads to efficient propagation of HIV-1. The selective chemokine receptors, including CXCR4 and CCR7, may play a role in this process, yet the viral factors regulating chemokine-dependent T cell migration remain relatively unclear. The functional cooperation between the CXCR4 ligand chemokine CXCL12 and the CCR7 ligand chemokines CCL19 and CCL21 enhances CCR7-dependent T cell motility in vitro as well as cell trafficking into the lymph nodes in vivo. In this study, we report that a recombinant form of a viral CXCR4 ligand, X4-tropic HIV-1 gp120, enhanced the CD4 T cell response to CCR7 ligands in a manner dependent on CXCR4 and CD4, and that this effect was recapitulated by HIV-1 virions. HIV-1 gp120 significantly enhanced CCR7-dependent CD4 T cell migration from the footpad of mice to the draining lymph nodes in in vivo transfer experiments. We also demonstrated that CXCR4 expression is required for stable CCR7 expression on the CD4 T cell surface, whereas CXCR4 signaling facilitated CCR7 ligand binding to the cell surface and increased the level of CCR7 homo- as well as CXCR4/CCR7 hetero-oligomers without affecting CCR7 expression levels. Our findings indicate that HIV-evoked CXCR4 signaling promotes CCR7-dependent CD4 T cell migration by up-regulating CCR7 function, which is likely to be induced by increased formation of CCR7 homo- and CXCR4/CCR7 hetero-oligomers on the surface of CD4 T cells.

Chemokines in tumor progression and metastasis

Chemokines play a vital role in tumor progression and metastasis. Chemokines are involved in the growth of many cancers including breast cancer, ovarian cancer, pancreatic cancer, melanoma, lung cancer, gastric cancer, acute lymphoblastic leukemia, colon cancer, non-small lung cancer, non-hodgkin's lymphoma, etc. The expression of chemokines and their receptors is altered in many malignancies and leads to aberrant chemokine receptor signaling. This review focuses on the role of chemokines in key processes that facilitate tumor progression including proliferation, senescence, angiogenesis, epithelial mesenchymal transition, immune evasion and metastasis.

Convolution of chemoattractant secretion rate, source density, and receptor desensitization direct diverse migration patterns in leukocytes

Chemoattractants regulate diverse immunological, developmental, and pathological processes, but how cell migration patterns are shaped by attractant production in tissues remains incompletely understood. Using computational modeling and chemokine-releasing microspheres (CRMs), cell-sized attractant-releasing beads, we analyzed leukocyte migration in physiologic gradients of CCL21 or CCL19 produced by beads embedded in 3D collagen gels. Individual T-cells that migrated into contact with CRMs exhibited characteristic highly directional migration to attractant sources independent of their starting position in the gradient (and thus independent of initial gradient strength experienced) but the fraction of responding cells was highly sensitive to position in the gradient. These responses were consistent with modeling calculations assuming a threshold absolute difference in receptor occupancy across individual cells of ~10 receptors required to stimulate chemotaxis. In sustained gradients eliciting low receptor desensitization, attracted T-cells or dendritic cells swarmed around isolated CRMs for hours. With increasing CRM density, overlapping gradients and high attractant concentrations caused a transition from local swarming to transient "hopping" of cells bead to bead. Thus, diverse migration responses observed in vivo may be determined by chemoattractant source density and secretion rate, which govern receptor occupancy patterns in nearby cells.

Sentinel node and mechanism of lymphatic metastasis

The validity and clinical usefulness of the sentinel node (SN) concept for breast cancer has been confirmed, and individualized limited surgery based on diagnosis of SN metastasis is presently performed. In the future, SN navigation surgery (SNNS) will be actively applied to the treatment of early gastric cancer, and an intraoperative real-time reverse transcription-polymerase chain reaction (RT-PCR) assay to detect SN micrometastasis of gastric cancer is under development. Not only anatomical factors, but also many other factors such as local immunosuppression in the SN and lymphoangiogenesis may be involved in development of SN micrometastasis, and clarification of the mechanisms of metastasis and development of treatment methods are awaited. (*English Translation of J Jpn Col Angiol 2008; 48: 137-142.).

Analysis of chemokine receptor CCR7 expression on porcine blood T lymphocytes using a CCL19-Fc fusion protein

The chemokine receptor CCR7 has been a useful marker for the characterization of human and mouse T cell subsets. We have produced the porcine CCR7 ligand CCL19 fused to the human IgG1 Fc fragment, and used it to analyse CCR7 expression in swine. CCL19-Fc bound to and induced the migration of cells expressing porcine CCR7 but not of untransfected cells, corroborating its specificity. On blood lymphocytes, CCL19-Fc labelled the majority of CD4(+) T cells expressing the 2E3 marker, associated with a naïve phenotype, whereas the 2E3(-) cells were mostly negative. Among CD8(+) T cells CCL19-Fc labelled two subsets: one, CD8β(hi) CD11a(lo) CD45RA(+), perforin(-/lo) , which produced low amounts of IFN-γ after stimulation, which might correspond to naïve cells; and a second small population of CD8β(lo) cells which expressed high levels of CD11a, and were mostly CD45RA(-), a phenotype which resembles that of human central memory T cells.

Engineering chemoattractant gradients using chemokine-releasing polysaccharide microspheres

Spatial and temporal concentration gradients of chemoattractants direct many biological processes, especially the guidance of immune cells to tissue sites during homeostasis and responses to infection. Such gradients are ultimately generated by secretion of attractant proteins from single cells or collections of cells. Here we describe cell-sized chemoattractant-releasing polysaccharide microspheres, capable of mimicking chemokine secretion by host cells and generating sustained bioactive chemokine gradients in their local microenvironment. Exploiting the common characteristic of net cationic charge and reversible glycosaminoglycan binding exhibited by many chemokines, we synthesized alginate hydrogel microspheres that could be loaded with several different chemokines (including CCL21, CCL19, CXCL12, and CXCL10) by electrostatic adsorption. These polysaccharide microspheres subsequently released the attractants over periods ranging from a few hours to at least 1 day when placed in serum-containing medium or collagen gels. The generated gradients were able to attract cells more than hundreds of microns away to make contact with individual microspheres. This versatile system for chemoattractant delivery could find applications in immunotherapy, vaccines and fundamental chemotaxis studies in vivo and in vitro.

Expression of the C-C chemokine receptor 7 mediates metastasis of breast cancer to the lymph nodes in mice

C-C chemokine receptor 7 (CCR7) controls lymphocyte migration to secondary lymphoid organs. Although CCR7 has been implicated in targeting the metastasis of cancers to lymph nodes, the role of CCR7 in the metastasis of breast cancer, along with the molecular mechanisms that are controlled by CCR7 that target breast cancer metastasis to the lymph nodes, has yet to be defined. To explore the cellular and molecular mechanisms of breast cancer cell migration to the lymph nodes, we used the mouse MMTV-PyVmT mammary tumor cells (PyVmT) transfected with CCR7 and the human CCR7-expressing MCF10A and MCF7 mammary cell lines. We found that the CCR7 ligands CCL19 and CCL21, controlled cell migration using the β(1)-integrin heterodimeric adhesion molecules. To define a physiological significance for CCR7 regulation of migration, we used the FVB syngeneic mouse model of metastatic breast cancer. When CCR7-negative PyVmT cells transfected with control vector were orthotopically transferred to the mammary fat pad of FVB mice, tumors metastasized to the lungs (10/10 mice) but not to the lymph nodes (0/10). In contrast, CCR7-expressing PyVmT (CCR7-PyVmT) cells metastasized to the lymph nodes (6/10 mice) and had a reduced rate of metastasis to the lungs (4/10 mice). CCR7-PyVmT tumors grew significantly faster than PyVmT tumors, which mirrored the growth in vitro, of CCR7-PyVmT, MCF7, and MCF10A mammospheres. This model provides tools for studying lymph node metastasis, CCR7 regulation of tumor cell growth, and targeting of breast cancer cells to the lymph nodes.

Embryonic trafficking of gammadelta T cells to skin is dependent on E/P selectin ligands and CCR4

Dendritic epidermal T cells (DETC) express an invariant Vgamma3/Vdelta1 T-cell receptor, appear in fetal epidermis, and form a population of resident epidermal T cells. Their temporal development in the thymus has been studied extensively. However, little is known about the mechanisms involved in the embryonic trafficking of DETC from thymus to epidermis. We demonstrate that DETC in adult skin, as well as the DETC precursors in fetal thymus, express E and P selectin ligands (E- and P-lig). Mice deficient in alpha1,3 fucosyltransferases IV and VII (FTIV/VII) cannot synthesize the carbohydrate motifs that form key elements of these selectin ligands. The numbers of DETC in the epidermis of FTIV/VII(-/-) mice were dramatically reduced compared with normal mice. However, the development of DETC precursors in fetal thymus was identical in normal and FTIV/VII(-/-) mice, suggesting that the DETC precursors produced in FTIV/VII(-/-) mice could not traffic effectively to skin because they lack E- and P-lig. We tested this hypothesis by daily injection of blocking antibodies against E and P selectin into pregnant mice. Mice born from dams treated with anti-selectin antibodies, but not those born from dams treated with isotype control, had significantly diminished numbers of DETC. To test the role of chemokine receptors in DETC skin homing, we examined skin from CCR4(-/-) and CCR10(-/-) mice, respectively. DETC were significantly reduced in CCR4(-/-) mice but were present at normal levels in CCR10(-/-) mice. Our results present evidence for the crucial role of trafficking molecules in embryonic migration of DETC precursors to skin.

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.

Sentinel lymph node as a target of molecular diagnosis of lymphatic micrometastasis and local immunoresponse to malignant cells

The sentinel lymph node (SLN) is defined as the lymph node(s) first receiving lymphatic drainage from the site of the primary tumor. The histopathological status of SLN is one of the most significant predictors of recurrence and overall survival for most clinical stage I/II solid tumors. Recent progress in molecular techniques has demonstrated the presence of micrometastatic tumor cells in SLN. There is now a growing body of data to support the clinical relevance of SLN micrometastasis in a variety of solid tumors. Increasing the sensitivity of occult tumor cell detection in the SLN, using molecular-based analysis, should enable a more accurate understanding of the clinical significance of various patterns of micrometastatic nodal disease. The establishment of metastasis to SLN might not be simply reflected by the flow dynamics of lymphatic fluid that drains from the primary site to the SLN, and the transportation of viable cancer cells. Recent studies have demonstrated that primary tumors can actively induce lymphangiogenesis and promote SLN metastasis. Moreover chemokine receptors in tumor cells may facilitate organ-specific tumor metastasis in many human cancers and some experimental models. In contrast, recent clinical and preclinical studies regard SLN as the first lymphoid organ to respond to tumor antigenic stimulation. SLN dramatically show morphological, phenotypical and functional changes that indicate immune suppression by tumor cells. The immune suppression in SLN results in failure of prevention or eradication of tumor metastasis. The mechanism of immunomodulation remains unclear; however, several regulatory molecules produced by tumor cells and tumor-associated macrophages or lymphocytes are likely to be responsible for inducing the immune suppression in SLN. Further studies may develop a novel immunotherapy that overcomes tumor-induced immune suppression and can prevent or eradicate SLN metastasis.

Chemokines CCL19 and CCL21 promote activation-induced cell death of antigen-responding T cells

Secondary lymphoid organs (SLOs) provide a niche for the initiation and regulation of T-cell responses, but the mechanisms have been poorly understood. We investigated the influence of chemokines CCL19 and CCL21 constitutively expressed in SLOs on activation-induced cell death (AICD) of CD4+ T cells. When paucity of lymph node T cells (plt) mutant mice lacking expression of CCL19/CCL21 were primed with OVA/CFA, both expansion of OVA-responding CD4+ T cells in the draining lymph nodes and an in vitro recall response were prolonged as compared with responses in wild-type (WT) mice. The apoptotic cell frequency among OVA-responding CD4+ T cells was similarly low in plt/plt and WT mice during the clonal expansion phase. However, during the clonal contraction phase, the frequency never increased in plt/plt mice, whereas in WT mice it continuously increased to a peak 18 days after immunization. The presence of CCL19/CCL21 during the in vitro stimulation of CD4+ T cells with anti-CD3 plus anti-CD28 significantly enhanced in vitro AICD induction of the restimulated T cells, partially through enhancing expression of Fas ligand. Our results suggest that CCL19/CCL21 produced by stromal cells and antigen-presenting cells regulate CD4+ T-cell immune responses in SLOs by promoting AICD.

Homeostatic Lymphoid Chemokines Synergize with Adhesion Ligands to Trigger T and B Lymphocyte Chemokinesis

Homeostatic chemokines such as CCL19, CCL21, and CXCL13 are known to elicit chemotaxis from naive T and B cells and play a critical role in lymphocyte homing to appropriate zones within secondary lymphoid organs (SLO). Here we tested whether CCL21 and CXCL13 modulate murine lymphocyte motility in the absence of concentration gradients, using videomicroscopy to directly observe the migration of single cells. CCL21 treatment of T cells induced rapid polarization and sustained random migration with average speeds of 5.16 +/- 2.08 microm/min; B cell migration (average velocity 4.10 +/- 1.58 microm/min) was similarly induced by CXCL13. Migration required the presence of both chemokine and adhesion ligands and was sustained for >24 h. Furthermore, in in vitro assays modeling the relative infrequency of Ag-specific T cell-dendritic cell (DC) encounters during primary immune responses, we found that CCL21 addition to T-DC cocultures accelerated the kinetics of CD69 up-regulation and enhanced by 2-fold the proliferation of Ag-specific T cells in a manner dependent on G-protein-coupled receptor signaling in T cells. These results suggest that homeostatic chemokines could substantially impact the dynamics and priming of lymphocytes within SLO even in the absence of significant concentration gradients.

Dynamics of dendritic cell migration and the subsequent induction of protective immunity in the lung after repeated airway challenges by nontypeable Haemophilus influenzae outer membrane protein

To determine the dynamics of dendritic cell (DCs) migration and their role in recurrent infections by nontypeable Haemophilus influenzae (NTHi), the migration of mature DC into pulmonary lymph nodes (LN) and the development of a P6-specific immune response and bacterial clearance in the lung were examined after repeated airway challenges with outer membrane protein (OMP) at 1-week intervals in mice. Although the migration of mature DC into the pulmonary LN is attenuated after repeated airway challenge with OMP, the in vitro P6-specific T cell proliferation in the cultured pulmonary LN cells was enhanced and was subsequently linked to the development of P6-specific IgA production and the development of protective immunity in the airway of mice.

Anti-tumor responses induced by chemokine CCL19 transfected into an ovarian carcinoma model via fiber-mutant adenovirus vector

Considerable attention has recently been paid to the application of chemokines to cancer immunotherapy because of their chemotactic affinity for a variety of immune cells and because several chemokines are strongly angiostatic. In the present study, the recombinant adenovirus vectors encoding chemokine CCL19 or XCL1 in an E1 cassette (AdRGD-mCCL19 and AdRGD-mXCL1) were developed. The constructed fiber-mutant adenovirus vector, which contained the integrin-targeting Arg-Gly-Asp (RGD) sequence in the fiber knob, notably enhanced the transfection efficiency to OV-HM ovarian carcinoma cells compared to that induced by conventional adenovirus vector. The results of an in vitro chemotaxis assay for chemokine-encoding vector demonstrated that both AdRGD-mCCL19 and AdRGD-mXCL1 could induce the migration of cells expressing specific chemokine receptors. Of the two chemokine-encoding vectors evaluated in vivo, AdRGD-mCCL19 showed significant tumor-suppressive activity in B6C3F1 mice via transduction into OV-HM cells, whereas XCL1 did not exhibit any notable anti-tumor effects, suggesting that CCL19 may be a candidate for cancer immunotherapy.

Human herpesvirus 7 open reading frames U12 and U51 encode functional beta-chemokine receptors

Human herpesvirus 7 (HHV-7), which belongs to the betaherpesvirus subfamily and infects mainly CD4+ T cells in vitro, infects children during infancy. HHV-7 contains two genes, U12 and U51, that encode putative homologs of cellular G-protein-coupled receptors. To analyze the biological function of the U12 and U51 genes, we cloned these genes and expressed the proteins in cells. U12 and U51 encoded functional calcium-mobilizing receptors for beta-chemokines, which include thymus and activation-regulated chemokine (TARC), macrophage-derived chemokine (MDC), EBI1-ligand chemokine (ELC), and secondary lymphoid-tissue chemokine (SLC), but not for other chemokines, suggesting that the chemokine selectivities of the U12 and U51 products were distinct from those of the known mammalian chemokine receptors. ELC and SLC induced migration in Jurkat cells stably expressing U12, but TARC and MDC did not. In contrast, none of these chemokines induced migration in Jurkat cells stably expressing U51. Together, these data indicate that the products of U12 and U51 may play important and different roles in the pathogenesis of HHV-7 through transmembrane signaling.

Epigenetic up-regulation of C-C chemokine receptor 7 and C-X-C chemokine receptor 4 expression in melanoma cells

Histone deacetylation and DNA methylation establish epigenetic modifications, which through chromatin remodeling may result in gene silencing. We hypothesized that chemokine receptors C-C chemokine receptor 7 (CCR7) and C-X-C chemokine receptor 4 (CXCR4) on melanoma cells undergo epigenetic regulation. We investigated whether a histone deacetylase inhibitor and a demethylating agent influence CCR7 and CXCR4 expression on melanoma cells. Initially, microarray analysis was done to screen changes in chemokine receptor expression on melanoma cells after treatment with trichostatin A (TSA) and 5-Aza-2-deoxycytidine (5-Aza). CCR7 and CXCR4 mRNA expression were uniformly altered and selected for further investigation. Quantitative real-time reverse transcription-PCR assay, immunohistochemistry, and Western blot analysis were used to assess changes in mRNA and protein expression induced by TSA and 5-Aza in melanoma lines. Cell migration assays were conducted to assess the effects of altered CCR7 and CXCR4 expression on cell function. Treatment with TSA or 5-Aza increased gene expression of both CCR7 and CXCR4 in melanoma lines. TSA was the strongest enhancer. With combined treatment, CCR7 and CXCR4 mRNA expression was also up-regulated. Immunohistochemistry after combined treatment showed enhanced staining of both CCR7 and CXCR4 compared with control cells. Melanoma cell migration in TSA- and 5-Aza-treated cells was 7- and 2-fold higher than control cells for CCR7 and CXCR4, respectively. In summary, a histone deacetylase inhibitor and a demethylating agent up-regulated CCR7 and CXCR4 expression on melanoma cells. This increase in chemokine receptor expression correlated with functional activity. Most importantly, we have identified an epigenetic mechanism that may endogenously regulate chemokine receptor expression on melanoma cells.

CCL21 chemokine regulates chemokine receptor CCR7 bearing malignant melanoma cells

PURPOSE

The chemokine CC-ligand 21/secondary lymphoid tissue chemokine (CCL21/SLC) regulates the homing of naïve T cells and dendritic cells that express CC-chemokine receptor 7 (CCR7) from distant sites to lymphoid tissue such as lymph nodes. We hypothesized that CCL21/SLC regulates the migration of CCR7-bearing melanoma cells from a primary lesion to regional tumor-draining lymph nodes.

EXPERIMENTAL DESIGN

Quantitative real-time reverse transcriptase-PCR (qRT) assay and immunohistochemistry (IHC) were used to assess the level of CCR7 expression in melanoma cell lines and in primary and metastatic melanoma tumors. Cell migration assay using melanoma cell lines was performed under the induction of CCL21/SLC. The CCL21/SLC expression level in tumor-draining sentinel lymph nodes (SLNs) was assessed by both qRT assay and IHC.

RESULTS

Melanoma cell lines and tumors demonstrated heterogeneous expression of CCR7 mRNA by qRT assay. There was strong functional correlation between CCR7 mRNA expression and cell migration induced by CCL21/SLC. IHC evidence of CCR7 expression in primary melanomas significantly (P = 0.02) correlated with Breslow thickness. Assessment of SLN from 55 melanoma patients by qRT assay demonstrated that CCL21/SLC mRNA expression level was significantly (P = 0.008) higher in pathologically melanoma-negative SLNs than in melanoma-positive SLNs.

CONCLUSIONS

This report demonstrates a potential mechanism for recruitment and homing of CCR7(+) metastatic melanoma cells to tumor-draining lymph nodes, which express CCL21/SLC. The study also suggests that lymph nodes bearing metastasis may suppress CCL21/SLC production.

Expression of CCR7 in multiple sclerosis: implications for CNS immunity

It is unclear how immune cells traffic between the lymphoid compartment and the central nervous system (CNS), which lacks lymphatic vessels and is shielded by the blood-brain barrier. We studied the expression of CCR7, a chemokine receptor required for migration of T cells and dendritic cells (DCs) to lymphoid organs, in the CNS of patients with multiple sclerosis (MS) to gain insight into pathways for CNS immune cell trafficking. Inflamed MS lesions contained numerous CCR7+ myeloid cells expressing major histocompatibility complex class II, CD68 and CD86, consistent with maturing DCs. CCR7+ DCs also were identified in cerebrospinal fluid (CSF). These observations suggested that the afferent limb of CNS immunity is comprised, in part, of DCs, which are generated within the CNS and migrate to deep cervical lymph nodes through the CSF after antigen capture. Ninety percent of CSF T cells expressed CCR7 and CSF from patients with MS was relatively depleted of CCR7-negative effector-memory T cells. In contrast, all T cells in parenchymal MS lesions lacked CCR7, indicating local retention and differentiation of central-memory T cells upon restimulation by antigen within the CNS. These data suggested that the efferent limb of CNS immunity is executed by central-memory T cells, which enter CSF directly from the circulation.

Identification of cell surface targets for HIV-1 therapeutics using genetic screens

Human immunodeficiency virus (HIV) drugs designed to interfere with obligatory utilization of certain host cell factors by virus are less likely to encounter development of resistant strains than drugs directed against viral components. Several cellular genes required for productive infection by HIV were identified by the use of genetic suppressor element (GSE) technology as potential targets for anti-HIV drug development. Fragmented cDNA libraries from various pools of human peripheral blood mononuclear cells (PBMC) were expressed in vitro in human immunodeficiency virus type 1 (HIV-1)-susceptible cell lines and subjected to genetic screens to identify GSEs that interfered with viral replication. After three rounds of selection, more than 15000 GSEs were sequenced, and the cognate genes were identified. The GSEs that inhibited the virus were derived from a diverse set of genes including cell surface receptors, cytokines, signaling proteins, transcription factors, as well as genes with unknown function. Approximately 2.5% of the identified genes were previously shown to play a role in the HIV-1 life cycle; this finding supports the biological relevance of the assay. GSEs were derived from the following 12 cell surface proteins: CXCR4, CCR4, CCR7, CD11C, CD44, CD47, CD68, CD69, CD74, CSF3R, GABBR1, and TNFR2. Requirement of some of these genes for viral infection was also investigated by using RNA interference (RNAi) technology; accordingly, 10 genes were implicated in early events of the viral life cycle, before viral DNA synthesis. Thus, these cell surface proteins represent novel targets for the development of therapeutics against HIV-1 infection and AIDS.

Regulation of CXCR4 expression in human T lymphocytes by calcium and calcineurin

Principally expressed on the surface of T lymphocytes, the chemokine and HIV receptor CXCR4 has been shown to serve key roles in both chemotaxis and HIV-1-entry into T cells. Understanding the regulation of CXCR4 expression is therefore of paramount importance to further elucidating its endogenous role and contributions to HIV-1 pathogenesis. Using an RNase protection assay (RPA), we have demonstrated that mitogenic stimulation of purified human peripheral blood T lymphocytes (PBL) decreased CXCR4 mRNA relative to unstimulated controls in a calcineurin-dependent manner; an expression pattern mimicked by the chemokine receptor CCR7. A change in transcriptional activity, not in mRNA stability, was required for control of CXCR4 and CCR7 expression. Changes in CXCR4 mRNA expression translated into a stimulation- and calcineurin-dependent decrease in cell surface CXCR4 expression. We have previously demonstrated that CXCR4 mRNA and protein is regulated by cAMP; here we show that calcium and calcineurin signaling pathways modify cAMP-driven changes. Moreover, we provide data supporting a role for the transcription factor YY1 in calcineurin-dependent regulation of CXCR4 expression.

Characterization of CC-chemokine receptor 7 expression on murine T cells in lymphoid tissues

Expression of the lymph node homing and CC-chemokine receptor 7 (CCR7), with L-selectin (CD62L), has been shown to divide human memory T cells into two functionally distinct subsets. We generated a polyclonal antibody against murine CCR7 and used this antibody to study CCR7 expression on murine T-cell subsets. Using flow cytometric staining of T cells for visualisation expression of CCR7 in association with CD62L and CD44, a major population of CD4 or CD8 T cells expressing CCR7 were found to be CD62Lhigh CD44low, which would suggest a naïve cell phenotype. By analogy with human studies, memory cells could be subdivided into CCR7high CD62Lhigh CD44high (central memory) and CCR7low CD62Llow CD44high (effector memory). The proportions of these populations were different in lymph node, blood and spleen. Functional, short-term in vitro polyclonal stimulation of blood, spleen and lymph node cells from naive mice demonstrated that CCR7high CD4 T cells produced predominantly interleukin (IL)-2, whereas CCR7low CD4 T cells produced both IL-2 and interferon-gamma (IFN-gamma). However, in contrast to previously published reports, the CCR7high CD8 T-cell subpopulation produced both IFN-gamma and IL-2. Analysis of effector T cells, induced by immunization in vivo, showed that a proportion of activated naïve CD4 T cells down-regulated CCR7 only after multiple cell divisions, and this coincided with the down-regulation of CD62L and production of IL-4 and IFN-gamma. Finally, analysis of effector T cells during the phase of maximal clonal expansion of secondary immune responses in vivo indicated that the vast majority of both IL-2- and IFN-gamma-producing cells are CCR7low, while few cytokine-expressing CCR7high T cells were detected. Our results support the hypothesis, developed from studies with human cells, that CCR7 may separate functionally different murine memory T-cell subpopulations, but indicate additional complexity in that CCR7high CD8 T cells also may produce IFN-gamma.

Human herpesvirus 7 open reading frame U12 encodes a functional beta-chemokine receptor

Human herpesvirus 7 (HHV-7), which belongs to the betaherpesvirus subfamily, infects mainly CD4+ T cells in vitro and infects children during infancy. After the primary infection, HHV-7 becomes latent. HHV-7 contains two genes (U12 and U51) that encode putative homologs of cellular G-protein-coupled receptors. To analyze the biological function of the U12 gene, we cloned the gene and expressed the U12 protein in cells. The U12 gene encoded a calcium-mobilizing receptor for the EBI1 ligand chemokine-macrophage inflammatory protein 3beta (ELC/MIP-3beta) but not for other chemokines, suggesting that the chemokine selectivity of the U12 gene product is distinct from that of the known mammalian chemokine receptors. These studies revealed that U12 activates distinct transmembrane signaling pathways that may mediate biological functions by binding with a beta-chemokine, ELC/MIP-3beta.

Phenotypic and functional analysis of T cells homing into the CSF of subjects with inflammatory diseases of the CNS

The recruitment of lymphocytes across the blood brain barrier (BBB) is mediated by adhesion molecules and chemokines. The expression of activation markers and of chemokine receptors on T cells homing to the nervous system (NS) may help define their functional state. In the cerebrospinal fluid (CSF) of subjects with inflammatory neurological diseases (IND), including multiple sclerosis, we observed an increased number of T cells coexpressing CXCR3 and CCR5 as well as T cells with a CD45RO+ CCR7+ CD27+ memory phenotype. A subset of CCR7+ T cells coexpressed CXCR3 and CCR5. We also detected an increased number of interferon-gamma-producing T cells in the CSF compared with peripheral blood, mostly but not exclusively in the CD45RO+ CCR7- CD27- compartment. T helper 1 (Th1) clones, established from the CSF of individuals with IND and from a healthy subject, similarly migrated to CXCL10, CXCL12, and CCL5. CXCL10, CXCL12, and CCL19 were increased in the CSF of individuals with neuroinflammation. These findings suggest that CSF is enriched in Th1-polarized memory T cells capable of differentiating into effector cells upon antigen encounter. These cells are recruited into the CSF by inducible chemokines. Thus, CSF represents a transitional station for T cells trafficking to and from the NS.

Differential expression of CCL19 by DC-Lamp+ mature dendritic cells in human lymph node versus chronically inflamed skin

De novo formation of lymphoid tissue is one of the characteristic features of chronic inflammation. The formation of T cell-mature dendritic cell (DC) clusters has been previously demonstrated in chronically inflamed skin infected with Candida albicans. A functional similarity was also found between chronic inflammation and the T-cell zone of lymph nodes (LNs), since a substantial fraction of phenotypically mature DCs in both tissues expressed CCL22 (macrophage-derived chemokine; MDC) and were closely surrounded by memory-type T cells expressing its receptor, CCR4. To analyse the nature of T cell-mature DC interactions further in chronically inflamed skin and LNs, the present study focuses on another chemokine system, namely CCL19 (EBI1 ligand chemokine; ELC), CCL21 (secondary lymphoid tissue chemokine; SLC) and their shared receptor, CCR7. RT-PCR analysis revealed expression of CCL19, CCL21, and CCR7 at high levels in LNs and at low levels in inflamed skin. Using immunohistochemistry, the majority of DC-Lamp(+) mature DCs in the T-cell area of LNs expressed CCL19 and were surrounded by CCR7(+) naïve-type lymphocytes, while CCL21 was expressed in reticular stromal cells and vascular endothelial cells. Very few mature DCs in LNs were found to express CCR7. In contrast, the majority of DC-Lamp(+) mature DCs in inflamed skin were totally negative for CCL19 and were surrounded by CCR7(-) memory-type T cells. Furthermore, CCL21 expression in the inflamed skin was detected in dermal lymphatic endothelial cells and rare CCR7(+) mature DCs were mostly seen within the lymphatic vessels. In normal skin, on the other hand, no cells immunoreactive for CCL19, CCL21, or CCR7 were found. The present study thus reveals a striking difference in the function of mature DCs between LNs and chronically inflamed skin.

Differing activities of homeostatic chemokines CCL19, CCL21, and CXCL12 in lymphocyte and dendritic cell recruitment and lymphoid neogenesis

Despite their widespread expression, the in vivo recruitment activities of CCL19 (EBV-induced molecule 1 ligand chemokine) and CXCL12 (stromal cell-derived factor 1) have not been established. Furthermore, although CXCL13 (B lymphocyte chemoattractant) has been shown to induce lymphoid neogenesis through induction of lymphotoxin (LT)alpha1beta2, it is unclear whether other homeostatic chemokines have this property. In this work we show that ectopic expression in pancreatic islets of CCL19 leads to small infiltrates composed of lymphocytes and dendritic cells and containing high endothelial venules and stromal cells. Ectopic CXCL12 induced small infiltrates containing few T cells but enriched in dendritic cells, B cells, and plasma cells. Comparison of CCL19 transgenic mice with mice expressing CCL21 (secondary lymphoid tissue chemokine) revealed that CCL21 induced larger and more organized infiltrates. A more significant role for CCL21 is also suggested in lymphoid tissues, as CCL21 protein was found to be present in lymph nodes and spleen at much higher concentrations than CCL19. CCL19 and CCL21 but not CXCL12 induced LTalpha1beta2 expression on naive CD4 T cells, and treatment of CCL21 transgenic mice with LTbetaR-Fc antagonized development of organized lymphoid structures. LTalpha1beta2 was also induced on naive T cells by the cytokines IL-4 and IL-7. These studies establish that CCL19 and CXCL12 are sufficient to mediate cell recruitment in vivo and they indicate that LTalpha1beta2 may function downstream of CCL21, CCL19, and IL-2 family cytokines in normal and pathological lymphoid tissue development.