Upregulation Of CCR7 Research Articles

Chemokine responsiveness of CD4+ CD25+ regulatory and CD4+ CD25− T cells from atopic and nonatopic donors

Allergic inflammation is associated with Th2-type T cells, which can be suppressed by CD4+ CD25+ regulatory T cells (Tregs). Both express chemokine receptors (CCR) 4 and CCR8, but the dynamics of expression and effect of atopic status are unknown. To examine the expression of chemokine receptors by CD4+ CD25+ and CD4+ CD25- T cells from atopic and nonatopic donors, and document response to allergen stimulation in vitro. Chemokine receptor expression was examined by flow cytometry and quantitative PCR of CD4+ CD25hi and CD4+ CD25- T cells from atopics and nonatopics. Responsiveness to chemokines was by actin polymerization. Dynamics of chemokine receptor expression in 6-day allergen-stimulated cultures was analysed by carboxyfluoroscein succinimidyl ester labelling. CD4+ CD25hi Tregs preferentially expressed CCR3, CCR4, CCR5, CCR6 and CCR8. CD4+ CD25hi Tregs responded to the chemokine ligands for CCR4, CCR6 and CCR8 (CCL17, 22, 20 and 1 respectively), with no differences between atopic and nonatopic donors. Over 6-day allergen stimulation, CD4+ CD25+ T-cells downregulated CCR4 and upregulated CCR7, in contrast to CD4+ CD25- effector cells, which downregulated CCR7 and upregulated CCR4. CCR4, CCR6 and CCR8 have potential roles in localization of both CD4+ CD25+ regulatory and CD4+ CD25- effector T cells to sites of allergic inflammation. Upregulation of CCR7 and downregulation of CCR4 upon allergen stimulation of Tregs may allow their recirculation from sites of inflammation, in contrast to retention of effector T cells.

CCR1 and CCR5 promote hepatic fibrosis in mice

Hepatic fibrosis develops as a response to chronic liver injury and almost exclusively occurs in a proinflammatory environment. However, the role of inflammatory mediators in fibrogenic responses of the liver is only poorly understood. We therefore investigated the role of CC chemokines and their receptors in hepatic fibrogenesis. The CC chemokines MIP-1alpha, MIP-1beta, and RANTES and their receptors CCR1 and CCR5 were strongly upregulated in 2 experimental mouse models of fibrogenesis. Neutralization of CC chemokines by the broad-spectrum CC chemokine inhibitor 35k efficiently reduced hepatic fibrosis, and CCR1- and CCR5-deficient mice displayed substantially reduced hepatic fibrosis and macrophage infiltration. Analysis of fibrogenesis in CCR1- and CCR5-chimeric mice revealed that CCR1 mediates its profibrogenic effects in BM-derived cells, whereas CCR5 mediates its profibrogenic effects in resident liver cells. CCR5 promoted hepatic stellate cell (HSC) migration through a redox-sensitive, PI3K-dependent pathway. Both CCR5-deficient HSCs and CCR1- and CCR5-deficient Kupffer cells displayed strong suppression of CC chemokine-induced migration. Finally, we detected marked upregulation of RANTES, CCR1, and CCR5 in patients with hepatic cirrhosis, confirming activation of the CC chemokine system in human fibrogenesis. Our data therefore support a role for the CC chemokine system in hepatic fibrogenesis and suggest distinct roles for CCR1 and CCR5 in Kupffer cells and HSCs.

Amyloid β Interaction with Receptor for Advanced Glycation End Products Up-Regulates Brain Endothelial CCR5 Expression and Promotes T Cells Crossing the Blood-Brain Barrier

How circulating T cells infiltrate into the brain in Alzheimer disease (AD) remains unclear. We previously reported that amyloid beta (Abeta)-dependent CCR5 expression in brain endothelial cells is involved in T cell transendothelial migration. In this study, we explored the signaling pathway of CCR5 up-regulation by Abeta. We showed that inhibitors of JNK, ERK, and PI3K significantly decreased Abeta-induced CCR5 expression in human brain microvascular endothelial cells (HBMECs). Chromatin immunoprecipitation assay revealed that Abeta-activated JNK, ERK, and PI3K promoted brain endothelial CCR5 expression via transcription factor Egr-1. Furthermore, neutralization Ab of receptor for advanced glycation end products (RAGE; an Abeta receptor) effectively blocked Abeta-induced JNK, ERK, and PI3K activation, contributing to CCR5 expression in HBMECs. Abeta fails to induce CCR5 expression when truncated RAGE was overexpressed in HBMECs. Transendothelial migration assay showed that the migration of MIP-1alpha (a CCR5 ligand)-expressing AD patients' T cells through in vitro blood-brain barrier model was effectively blocked by anti-RAGE Ab, overexpression of truncated RAGE, and dominant-negative PI3K, JNK/ERK, or Egr-1 RNA interference in HBMECs, respectively. Importantly, blockage of intracerebral RAGE abolished the up-regulation of CCR5 on brain endothelial cells and the increased T cell infiltration in the brain induced by Abeta injection in rat hippocampus. Our results suggest that intracerebral Abeta interaction with RAGE at BBB up-regulates endothelial CCR5 expression and causes circulating T cell infiltration in the brain in AD. This study may provide a new insight into the understanding of inflammation in the progress of AD.

Soybean isoflavones regulate dendritic cell function: implications in food allergy (79.16)

Abstract Peanuts and tree nuts are the most allergenic foods in children and adults in the U.S. Several allergens in peanut and soy share amino acid similarity by as much as 60%, yet soy allergy is less common and less severe compared to peanut allergy. Unlike peanuts, soybeans are rich in isoflavones such as genistein, daidzein and glycitein and are the most common source of isoflavones in the human food supply. Isoflavones are known to have anti-inflammatory and anti-oxidant properties. The maximum bioavailability of isoflavones is from the gut since they are quickly converted to inactive forms before entering the circulation. Therefore, we hypothesize that the active-isoflavones in the gut milieu are capable of modulating the initiation of immune responses to dietary-antigens by regulating DC function. In vitro, isoflavones inhibited lipopolysachharide (LPS) or cholera toxin (CT)-induced cell-surface expression of CD83, CD80 and CD86 in a dose dependent manner in human monocyte derived dendritic cells (MDDC). Isoflavone treatment augmented CT induced up-regulation of CXCR4 and CCR7. Isoflavone treated MDDC inhibited T cell proliferation in a mixed lymphocyte reaction and inhibited the secretion of Th2 cytokines. We hypothesize that these changes in DC function could induce tolerance to food allergens. Studies are underway to test this hypothesis in a peanut allergic mouse model.

Post-transcriptional regulation of adapter molecules by IL-10 inhibits TLR-mediated activation of antigen-presenting cells

Toll-like receptors (TLRs) act to sense the environment for microbial products and submit danger signals to antigen-presenting cells (APCs) resulting in activation of complex immune responses. In this study, we analyzed the function of human monocyte-derived APCs generated in vitro in the presence of interleukin (IL)-10 upon activation by TLR ligands. Exposure of these APCs to IL-10 resulted in a skewed phenotypic maturation in response to stimuli provided by the TLR ligands, a reduced cytokine production, such as IL-12, IL-6 or tumor necrosis factor-alpha, and impaired capacity to stimulate T-cell activation. Furthermore, CCR7 upregulation in APCs exposed to TLR stimulation as well as migration towards CCL19/MIP-3beta were strongly reduced. IL-10 was found to downregulate MyD88, IRAK1 (IL-1 receptor-associated kinase) and tumor necrosis factor receptor-associated factor 6, essential adaptor molecules for TLR signaling, and to decrease TLR-induced nuclear expression of the nuclear factor-kappaB transcription factors c-Rel and Rel-B as well as interferon regulatory factor (IRF)-3 and IRF-8. This was not due to the inhibition of the mitogen-activated protein kinase pathway, but was rather mediated by the blockage of the PI3K signaling cascade. Interestingly, the inhibition of proteins involved in TLR signaling, such as MyD88, IRAK1 and mammalian target of rapamycin, was due to a selective post-transcriptional regulation.

Methamphetamine enhances HIV-1 infectivity in monocyte derived dendritic cells.

The US is currently experiencing an epidemic of methamphetamine (Meth) use as a recreational drug. Recent studies also show a high prevalence of HIV-1 infection among Meth users. We report that Meth enhances HIV-1 infectivity of dendritic cells as measured by multinuclear activation of a galactosidase indicator (MAGI) cell assay, p24 assay, and LTR-RU5 amplification. Meth induces increased HIV-1 infection in association with an increase in the HIV-1 coreceptors, CXCR4 and CCR5, and infection is mediated by downregulation of extracellular-regulated kinase (ERK2) and the upregulation of p38 mitogen-activated protein kinase (MAPK). A p38 inhibitor (SB203580) specifically reversed the Meth-induced upregulation of the CCR5 HIV-1 coreceptor. The dopamine D2 receptor antagonist RS +/- sulpiride significantly reversed the Meth-induced upregulation of CCR5, demonstrating that the Meth-induced effect is mediated via the D2 receptor. These studies report for the first time that Meth fosters HIV-1 infection, potentially via upregulating coreceptor gene expression. Further, Meth mediates its regulatory effects via dopamine receptors and via downregulating ERK2 with a reciprocal upregulation of p38 MAPK. Elucidation of the role of Meth in HIV-1 disease susceptibility and the mechanism through which Meth mediates its effects on HIV-1 infection may help to devise novel therapeutic strategies against HIV-1 infection in high-risk Meth-using HIV-1-infected subjects.

Upregulation of the Chemokine Receptor CCR7 expression by HIF-1alpha and HIF-2alpha in non-small cell lung cancer.

CCR7 is closely related with the lymph node metastasis of non-small cell lung cancer. The objective of this work is to investigate the expressions of chemokine receptor CCR7, hypoxia inducible factor 1alpha (HIF-1alpha) and hypoxia inducible factor 2alpha (HIF-2alpha) protein in non small cell lung cancer and the relationships of their expression, and to study the mechanism of CCR7 upregulation in NSCLC. T he levels of expressions of CCR7, HIF-1alpha and HIF-2alpha protein were detected in 94 specimens of human primary non small cell lung cancer by immunohistochemical S-P method. Human lung adenocarcinoma cell line A549 cells were transfected by lipofection with HIF-1alpha siRNA, HIF-2alpha siRNA, the change of CCR7 was observed by RT-PCR and immunofluorescence staining. Correlations between the expression of CCR7 and HIF-1alpha, HIF-2alpha were respectively analyzed. Immunohistochemistry showed that CCR7 was distributed in cytoplasm and/or membrane of tumor cells, HIF-1alpha, HIF-2alpha was distributed in nucleus and/or cytoplasm of tumor cells. The levels of expressions of CCR7, HIF-1alpha and HIF-2alpha protein were found to be 75.53% (71/94), 54.25% (51/ 94) and 70.21% (66/94) in non small cell lung cancer, respectively. the levels of expression of CCR7 protein were closely related to the clinical stages (P <0.001) and lymph node metastasis (P <0.001) of non small cell lung cancer, but there was no correlation with age, gender, histology (P >0.05). Furthermore, A significant correlation were found among CCR7, Hif-1alpha and HIF-2alpha (r =0.272, P <0.01) (r =0.225, P <0.05). In addition, the expression of CCR7 mRNA and protein levels were decreased in the transfected specific HIF-1alpha, HIF-2alpha siRNA group (P <0.05). CCR7 expression is significantly associated with non small cell lung cancer invasion and metastasis. The upregulation of CCR7 is regulated by HIF-1alpha and HIF-2alpha in non small cell lung cancer.

Porin-incorporated liposome induces Toll-like receptors 2- and 6-dependent maturation and type 1 response of dendritic cell

Porin of Shigella dysenteriae was incorporated in liposome (PIL) and presented to mouse splenic dendritic cells (DC). PIL up-regulated Toll-like receptor (TLR) 2 and TLR6 on DC, showing that co-expression of the two TLRs is involved in recognition of porin. Detection of myeloid differentiating factor 88 (MyD88)-TLR2 complex confirmed interaction between the two for triggering the downstream signaling, which ultimately led to TLR2-dependent nuclear translocation of nuclear factor-kappa B. PIL-induced expression of MHC class II (I-Ab), CD40 and CD80 showed maturation of DC, whereas up-regulation of intercellular adhesion molecule-1 and CCR7 implicated the capacity of splenic DC to migrate. Induction of messenger ribonucleic acid for the chemokines, macrophage-inflammatory protein (MIP)-1alpha, MIP-1beta and regulated upon activation, normal T cell expressed and secreted indicated a strong bias of PIL for type 1 polarization that was supported by the intracellular expression and release of tumor necrosis factor (TNF)-alpha and IL-12. Along with CD40 and CD80 expression, release of the cytokines of CD11c+ JAWS II cells was inhibited by TLR2 or simultaneous TLR2 and 6 knockdown showing that recognition of PIL by the two TLRs is essential for DC activation and type 1 polarization. The signaling pathway initiated upon recognition of PIL by the TLRs was MyD88 dependent as confirmed by inhibition of IL-6, TNF-alpha and IL-12 release of MyD88-knockdown JAWS II cells. The maturation and polarization of DC induced T(h)1 phenotype, as evident from proliferation, activation and IFN-gamma release of allogeneic CD4+ T cells in response to PIL-stimulated DC, thereby suggesting that the adjuvant activity of PIL can successfully bridge the innate and adaptive immunity.

Chemokine receptor expression in non‐melanoma skin cancer

Previous studies suggest that chemokines and chemokine receptors have a role in the metastatic process. A correlation exists between the specific expression of these chemoattractive, pro-inflammatory cytokines and the ability of cancer to disseminate. Prior studies have shown that in metastatic melanoma and squamous cell carcinoma of the head and neck upregulation of CXC (alpha) chemokine receptor (CXCR)4 and CC (beta) chemokine receptor (CCR)7 expression is accompanied by downregulation of the chemokine receptor CCR6. However, the expression patterns of CCR6, CCR7 and CXCR4 in non-melanoma skin cancer have yet to be elucidated. The expression patterns of CCR6, CCR7 and CXCR4 were determined using an immunohistochemical approach on formalin-fixed, paraffin-embedded normal, pre-cancerous actinic (solar) keratosis, squamous cell carcinoma and basal cell carcinoma tissues. Analysis of chemokine receptor expression showed downregulation of CCR6 and upregulation of CCR7 and CXCR4 in potentially metastatic non-melanoma skin cancer, invasive squamous cell carcinoma, but this pattern did not exist in non-melanoma skin cancer with no metastatic potential, basal cell carcinoma; or actinic keratosis, when compared with normal skin. Chemokine receptor expression may influence the biological behavior of non-melanoma skin cancer. The exact mechanism by which this occurs requires further study.

Selected natural and synthetic retinoids impair CCR7- and CXCR4-dependent cell migration in vitro and in vivo

Dendritic cell (DC) migration to secondary lymphoid organs is a crucial step to initiate adaptive immune responses. This step requires the expression of a functional CCR7 chemokine receptor on DC undergoing maturation. Here, we show that the natural retinoid 9-cis retinoic acid (9cRA) and the synthetic retinoid fenretinide (4-HPR) specifically inhibit the functional up-regulation of CCR7 on maturing human DCs, without affecting early steps of DC maturation. As a consequence, mature DCs do not migrate in vitro toward the chemokine CCL19. Importantly, 4-HPR and 9cRA by inhibiting the expression of CCR7 on bone marrow-derived murine DCs dampen their in vivo migration to draining lymph nodes. 4-HPR also inhibits the expression of the chemokine receptors CXCR4, therefore, impairing in vitro migration of human DCs to CXCL12 and inhibiting in vivo the CXCR4-dependent migration of the posterior lateral line primordium (PLLp) in zebrafish embryos. Taken together, these data highlight a novel function of retinoids and suggest the possibility of using retinoids to treat inflammatory or autoimmune diseases.

HIV-1 matrix protein p17 induces human plasmacytoid dendritic cells to acquire a migratory immature cell phenotype

Numerical and functional defects in plasmacytoid dendritic cells (pDCs) are an important hallmark of progressive HIV-1 infection, yet its etiology remains obscure. HIV-1 p17 matrix protein (p17) modulates a variety of cellular responses, and its biological activity depends on the expression of p17 receptors (p17Rs) on the surface of target cells. In this study, we show that peripheral blood pDCs express p17Rs on their surface and that freshly isolated pDCs are sensitive to p17 stimulation. Upon p17 treatment, pDCs undergo phenotypic differentiation with up-regulation of CCR7. A chemotaxis assay reveals that p17-treated pDCs migrate in response to CCL19, suggesting that these cells may acquire the ability to migrate to secondary lymphoid organs. In contrast, p17 does not induce release of type I IFN nor does it enhance pDC expression of CD80, CD86, CD83, or MHC class II. Microarray gene expression analysis indicated that p17-stimulated pDCs down-regulate the expression of molecules whose functions are crucial for efficient protein synthesis, protection from apoptosis, and cell proliferation induction. Based on these results, we propose a model where p17 induces immature circulating pDCs to home in lymph nodes devoid of their ability to serve as a link between innate and adaptative immune systems.

Differential migration of human monocyte-derived dendritic cells after infection with prevalent clinical strains of Mycobacterium tuberculosis

Dendritic cells (DCs) play a key role in the host immune response to infections. Mycobacterium tuberculosis (MTB) can inhibit the maturation of DCs and impair their ability to stimulate T cell proliferation. Here, we assessed in vitro migratory behavior of human monocyte-derived DCs (MoDC) when infected with various MTB strains (H37Rv and prevalent clinical strains S7 and S10 from South India). The migration of Rv and S7 infected MoDC towards secondary lymphoid chemokine (CCL21) was 50% lower after 1 day of infection compared to LPS stimulation. This reduced cell migration may be due to a block in the chemokine receptor switch from CCR5 to CCR7 expression on MoDC. Only clinical strain S10 infected MoDC showed an up-regulation of CCR7 and down-regulation of CCR5 expression, similar to LPS stimulated MoDC. While Rv and S7 infected MoDC did not display any alteration in expression of these receptors. Similarly, Rv and S7 infected MoDC did not induce IL-8, IP-10 and MCP-1 chemokine production. This reduction in chemokine levels was reflected in the reduced chemoattraction of CD4 + T cells also. These findings suggest that there is variation in the stimulation of MoDC with different clinical strains of MTB and this variation may be dependent upon the virulence of the strain.

Autocrine CCR7 signaling is mediated by NF‐kappaB in SCCHN

The chemokine receptor CCR7 is a seven‐transmembrane G‐protein coupled receptor that is expressed by leukocytes and facilitates their chemotactic migration to the lymph nodes. However, aberrant CCR7 expression has been described in a number of human malignancies and is linked to metastatic behavior, pro‐survival, and invasive pathways. In squamous cell carcinoma of the head and neck (SCCHN), we have previously described the selective upregulation of CCR7 in metastatic, but not primary tumors. Strikingly, the metastatic SCCHN tumor cells also secrete and respond to the CCR7 ligands CCL19 and CCL21, suggesting that an autocrine signaling mechanism may promote self‐sufficiency of growth signals. Based on reports that the nuclear transcription factor NF‐kappaB regulates inflammatory genes involved in chemokine‐mediated tumorigenesis, we hypothesized that NF‐kappaB is a key mediator of autocrine CCR7 signaling in SCCHN. We identified four NF‐kappaB binding sites in the 900bp promoter region upstream of the CCR7 gene, and confirmed their activity using luciferase, EMSA and ChIP assays. Our findings argue that NF‐kappaB is important for the induction of CCR7 expression as well as for the propagation of downstream signaling pathways. The observed autocrine signaling and subsequent downstream NF‐kappaB activation appear to be important for the evolution and progression of metastatic SCCHN tumors.

Human Langerhans cells selectively activated via Toll-like receptor 2 agonists acquire migratory and CD4+T cell stimulatory capacity

In epidermal Langerhans cells (LCs), the expression pattern and the functions of TLRs have been poorly characterized. By using mAb, we show that LCs from human skin express TLR1, -2, -5, -6, and -9, the cognate receptors for detection of specific bacteria-derived molecules. As compared with other TLR agonists, LCs acquired a more matured phenotype when activated by specific bacterial or synthetic TLR2 agonists. In addition, monocyte-derived Langerin(+)/CD1c(+)LCs (CD1c(+)MoLCs) secreted higher amounts of IL-6 and TNF-alpha by stimulation via TLR2 than by stimulation via TLR3, -4, -5, -8, and -9. In contrast to MoLCs, dendritic cells, generated from the same donor monocytes, were activated by agonists of TLRs other than TLR2 as well. Lipopeptides triggering TLR2 induced IL-1R-associated kinase-1 phosphorylation and migration toward the chemokines CCL19 and CCL21 in epidermal LCs and CD1c(+)MoLCs. Up-regulation of CD86, CD83, and CCR7, TNF-alpha and IL-6, and NF-kappaB activation and proliferation of CD4(+)T cells could be inhibited TLR2-specific blockage using antibodies prior to TLR2 activation. Application of anti-TLR1, anti-TLR6, and anti-TLR2 indicated an exclusive role of TLR2 in IL-6 induction in human LCs. Collectively, our results show that TLR2 expressed by LCs mediates inflammatory responses to lipopeptides, which implicates a central role in sensing pathogens in human skin.

Immunosuppressant Sinomenine Promotes Differentiation of Bone Marrow Progenitors to IL-10-Producing Ialow Regulatory Dendritic Cells Leading to the Prolongation of Allograft Survival.

Sinomenine (SN), an immunosuppressive compound derived from the Chinese medicinal plant Sinomenium acutum, effectively inhibits both proinflammatory factor production and lymphocyte proliferation. However, the effects of SN on dendritic cells (DC), the professional antigen-presenting cells, have not been elucidated. In this study, we examined the effects of SN on DC generation, maturation and function. We found that SN affected DC in a dose dependent manner; significantly inhibiting surface expression of MHC class II, CD86, and CD40, production of IL-12, TNF-a, IL-1b, and T cell-allostimulatory activity. SN targets antigen-presenting capacity of DC not only via the MHC class II pathway, but also impairs DC migration by inhibiting LPS-induced up-regulation of CCR7 and CXCR4 expression. These inhibitory effects on DC may be partially due to SN-mediated suppression of NF-kB and p38 MAPK pathways. Further study showed that SN-treated DC (DC-SN) induce donor-specific T cell hyporesponsiveness and trigger generation of IL-10-producing T regulatory-like cells in vitro. In vivo transplant studies revealed that, compared to pretreatment with immature DC, pretreatment of recipients with DC-SN could significantly prolong allograft survival, although long-term allograft acceptance was not achieved. Importantly, pretreatment of recipients with DC-SN in combination with SN administration profoundly prolonged allograft survival, resulting in long-term survival of 30% of allografts. Increased generation of CD4+CD25+ Treg cells and enhanced microchimerism in recipients brought on by combination treatment may contribute to this extension of allograft lifespan. Our results demonstrate that SN can promote bone marrow progenitors differentiation to IL-10-producing (Ialow) regulatory DC which contribute to induction of tolerance by increase generation of Treg cells.

Priming of CD4+ T cells with porin of Shigella dysenteriae activates the cells toward type 1 polarization

Macrophages treated with porin of Shigella dysenteriae were potent stimulators of naive T(h) cells since the porin-pulsed macrophages strongly proliferated the T cells and up-regulated the activation molecules CD69 and CD25 on CD4(+) T cells in allogeneic mixed leukocyte reaction. Immunization of C57BL/6 mice with porin selectively induced the intracellular expression and release of IFN-gamma and had no effect on IL-4 expression. In parallel to the predominant release of the T(h)1 cytokine IFN-gamma, up-regulation of CCR5 on the immune CD4(+) T cells and messenger ribonucleic acid (mRNA) expression of the T cell chemokines macrophage inflammatory protein-1 alpha and regulated on activation normal T cell expressed and secreted showed T(h)1 bias. The porin-primed CD4(+) T cells expressed the mRNA for T-box expressed in T cells, a T(h)1-specific transcription factor confirming the adjuvant-induced transition of T cells to polarized effector T(h)1 cells. The immune CD4(+) T cells proliferated and released IL-2 and IFN-gamma profoundly in response to re-challenge with porin-pulsed macrophages but not to BSA-pulsed macrophages in vitro, which demonstrated the presence of porin-specific CD4(+) T cells of T(h)1 phenotype. The study highlights that porin has the capacity of an adjuvant to unfold and maintain the T cell function and thereby to activate adaptive immunity.

Chemokine Receptor Expression in Oral Squamous Cell Carcinoma: Correlation with Growth Factor- and Cytokine-mediated Cell Migration in vitro

Metastasis is the chief cause of mortality in cancer patients. Recently, chemokines and chemokine receptors were shown to play an important role in the metastasis of various cancers. We examined the role of chemokine receptor-mediated signaling in the invasion potential of human oral squamous cell carcinoma (OSCC) cell lines that were derived from 5 primary tumors and 6 cervical lymph node metastases. Comprehensive analysis of the mRNAs for human chemokine receptors showed that the OSCC cell lines had uniform expression patterns of chemokine receptors. Overall, there were no consistent differences in the expression of chemokine receptors between primary site- and lymph node metastasis-derived cell lines. However, a highly invasive OSCC cell line (SAS-H1) expressed up-regulation of CCR5, CCR6, CCR7, CXCR1, CXCR6 and CX3CR1 compared to a poorly invasive OSCC cell line (SAS-L1). Then we examined whether factors in the tumor microenvironment regulated chemokine receptor expression in SAS-H1 cells. Specifically, transforming growth factor (TGF) -β1 enhanced the expression of CCR5, CCR6, CCR7 and CX3CR1. Pretreatment of SAS-H1 cells with transforming growth factor (TGF) -β1 increased the expression of CCR7 and CX3CR1, and then enhanced CCL21- and CX3CL1-induced directional migration (1.5-fold enhancement as compared with untreated control). In addition, CX3CL1 increased the adhesion of SAS-H1 cells on uncoated tissue culture plates. Neither chemokine stimulated cell proliferation. Treatment of SAS-H1 cells with CX3CL1 activated the phosphotidylinositol-3-kinase (PI3K) and MEK signal transduction pathways. Our results suggest that chemokine receptor-mediated signaling is involved in the local invasion and metastasis of human OSCC.

Dendritic Cells Break Bonds to Tolerize

Typically, dendritic cells (DCs) induce peripheral tolerance under steady state but immunity during inflammation or infection. In this issue of Immunity, Jiang et al. (2007) identify disruption of E-cadherin interactions as a unique maturation pathway by which DCs are capable of mediating tolerance.

Disruption of E-Cadherin-Mediated Adhesion Induces a Functionally Distinct Pathway of Dendritic Cell Maturation

The maturation of dendritic cells (DCs) after exposure to microbial products or inflammatory mediators plays a critical role in initiating the immune response. We found that maturation can also occur under steady-state conditions, triggered by alterations in E-cadherin-mediated DC-DC adhesion. Selective disruption of these interactions induced the typical features of DC maturation including the upregulation of costimulatory molecules, MHC class II, and chemokine receptors. These events were triggered at least in part by activation of the beta-catenin pathway. However, unlike maturation induced by microbial products, E-cadherin-stimulated DCs failed to release immunostimulatory cytokines, exhibiting an entirely different transcriptional profile. As a result, E-cadherin-stimulated DCs elicited an entirely different T cell response in vivo, generating T cells with a regulatory as opposed to an effector phenotype. These DCs induced tolerance in vivo and may thus contribute to the elusive steady-state "tolerogenic DCs."

Impaired CCR7 Expression on Plasmacytoid Dendritic Cells of HIV-Infected Children and Adolescents With Immunologic and Virologic Failure

Defects of plasmacytoid (p) and myeloid (m) dendritic cells (DCs) occur in HIV infection. The aim of this study was to evaluate the maturation and function of DCs in children with perinatal HIV infection who were on antiretroviral therapy. Twenty HIV-infected children (median age = 12.9 years) classified as immunologic/virologic responders and failures were evaluated in a whole-blood assay with resiquimod (RSQ), a potent agonist to Toll-like receptors 7 and 8, as the DC stimulant. In comparison to controls, pDC and mDC numbers were decreased in patients, but RSQ stimulation resulted in upregulation of CD83, CD80, and tumor necrosis factor-alpha in both DC subsets and upregulation of interferon (IFN)-alpha in pDCs. Patients with immunologic and virologic failure demonstrated a selective impairment in upregulation of lymph node homing marker CCR7 in pDCs. Plasma virus load was negatively correlated with IFNalpha and CCR7 expression, whereas CD4 percentage correlated only with CCR7 expression in pDCs. A novel defect of pDCs, impaired CCR7 upregulation, is described in association with immunologic or virologic failure. This deficiency could impair homing of pDCs to lymph nodes, leading to secondary defects of mDC maturation and poor T-cell activation.