Dendritic cells support sequential reprogramming of chemoattractant receptor profiles during naive to effector T cell differentiation

Improving Reliability of Immunological Assays by Defining Minimal Criteria for Cell Fitness

Human PBMC-based assays are often used as biomarkers for the diagnosis and prognosis of disease, as well as for the prediction and tracking of response to biological therapeutics. However, the development and use of PBMC-based biomarker assays is often limited by poor reproducibility. Complex immunological assays can be further complicated by variation in cell handling before analysis, especially when using cryopreserved cells. Variation in postthaw viability is further increased if PBMC isolation and cryopreservation are done more than a few hours after collection. There is currently a lack of evidence-based standards for the minimal PBMC viability or "fitness" required to ensure the integrity and reproducibility of immune cell-based assays. In this study, we use an "induced fail" approach to examine the effect of thawed human PBMC fitness on four flow cytometry-based assays. We found that cell permeability-based viability stains at the time of thawing did not accurately quantify cell fitness, whereas a combined measurement of metabolic activity and early apoptosis markers did. Investigation of the impact of different types and levels of damage on PBMC-based assays revealed that only when cells were >60-70% live and apoptosis negative did biomarker values cease to be determined by cell fitness rather than the inherent biology of the cells. These data show that, to reproducibly measure immunological biomarkers using cryopreserved PBMCs, minimal acceptable standards for cell fitness should be incorporated into the assay protocol.

Release from persistent T cell receptor engagement and blockade of aryl hydrocarbon receptor activity enhance IL-6-dependent mouse follicular helper T-like cell differentiation in vitro

Follicular helper T (Tfh) cells are crucial for humoral immunity. Dysregulation of Tfh cell differentiation can cause infectious, allergic, and autoimmune diseases. To elucidate the molecular mechanisms underlying Tfh cell differentiation, we attempted to establish an in vitro mouse model of Tfh cell differentiation in the absence of other cell types. Various cytokines and cell surface molecules are suggested to contribute to the differentiation. We found that stimulating naïve CD4+ T cells with immobilized antibodies to CD3, ICOS, and LFA-1 in the presence of soluble anti-CD28 antibody, IL-6, and antibodies that block IL-2 signaling for 3 days induced the expression of Bcl6 and Rorc(γt), master regulator genes of Tfh and Th17 cells, respectively. TGF-β significantly enhanced cell proliferation and Bcl6 and Rorc(γt) expression. An additional 2 days of culture without immobilized antibodies selectively downregulated Rorc(γt) expression. These cells produced IL-21 and promoted B cells to produce IgG antibodies. Adding the aryl hydrocarbon receptor (AhR) antagonist CH-223191 to the T cell culture further downregulated Rorc(γt) expression without significantly affecting Bcl6 expression, and upregulated expression of a key Tfh marker, CXCR5. Although their CXCR5 expression levels were still not high, the CH-223191-treated cells showed chemotactic activity towards the CXCR5 ligand CXCL13. On the other hand, AhR agonists upregulated Rorc(γt) expression and downregulated CXCR5 expression. These findings suggest that AhR activity and the duration of T cell receptor stimulation contribute to regulating the balance between Tfh and Th17 cell differentiation. Although this in vitro system needs to be further improved, it may be useful for elucidating the mechanisms of Tfh cell differentiation as well as for screening physiological or pharmacological factors that affect Tfh cell differentiation including CXCR5 expression.

MCP-1/IL-12 ratio expressions correlated with adventitial collagen depositions in renal vessels and IL-4/IFN-γ expression correlated with interstitial collagen depositions in the kidneys of dogs with canine leishmaniasis

Collagen deposition is a common event in chronic inflammation, and canine Leishmaniosis (CanL) is generally associated with a long and chronic evolution. Considering that the kidney shows fibrinogenic changes during CanL, and the balance of cytokines/chemokines regulates the profibrinogenic and antifibrinogenic immune responses differently, it can be hypothesized that the balance of cytokines/chemokines can be differentially expressed in the renal tissue in order to determine the expression of collagen depositions in the kidneys. This study aimed to measure collagen deposition and to evaluate cytokine/chemokine expressions in the kidney by means of qRT-PCR in sixteen Leishmania-infected dogs and six uninfected controls. Kidney fragments were stained with hematoxylin & eosin (H&E), Masson's Trichrome, Picrosirius Red, and Gomori's reticulin. Intertubular and adventitial collagen depositions were evaluated by the morphometric approach. Cytokine RNA expressions were measured by means of qRT-PCR to identify molecules involved in chronic collagen depositions in kidneys with CanL. Collagen depositions were related to the presence of clinical signs, and more intense intertubular collagen depositions occurred in infected dogs. Adventitial collagen deposition, as morphometrically measured by the average area of the collagen, was more intense in clinically affected dogs than in subclinically infected dogs. TNF-α/TGF-β, MCP1/IL-12, CCL5/IL-12, IL-4/IFN-γ, and IL-12/TGF-β expressions were associated with clinical manifestations in dogs with CanL. The IL-4/IFN-α ratio was more commonly expressed and upregulated in clinically affected dogs, and downregulated in subclinically infected dogs. Furthermore, MCP-1/IL-12 and CCL5/IL-12 were more commonly expressed in subclinically infected dogs. Strong positive correlations were detected between morphometric values of interstitial collagen depositions and MCP-1/IL-12, IL-12, and IL-4 mRNA expression levels in the renal tissues. Adventitial collagen deposition was correlated with TGF-β, IL-4/IFN-γ, and TNF-α/TGF-β. In conclusion, our results showed the association of MCP-1/IL-12 and CCL5/IL-12 ratios with an absence of clinical signs, as well as an IL-4/IFN-α ratio with adventitial and intertubular collagen depositions in dogs with visceral leishmaniosis.

The reciprocal interactions between microglia and T cells in Parkinson's disease: a double-edged sword

In Parkinson's disease (PD), neurotoxic microglia, Th1 cells, and Th17 cells are overactivated. Overactivation of these immune cells exacerbates the disease process and leads to the pathological development of pro-inflammatory cytokines, chemokines, and contact-killing compounds, causing the loss of dopaminergic neurons. So far, we have mainly focused on the role of the specific class of immune cells in PD while neglecting the impact of interactions among immune cells on the disease. Therefore, this review demonstrates the reciprocal interplays between microglia and T cells and the associated subpopulations through cytokine and chemokine production that impair and/or protect the pathological process of PD. Furthermore, potential targets and models of PD neuroinflammation are highlighted to provide the new ideas/directions for future research.

Chemokine receptor 4 expression on blood T lymphocytes predicts severity of major depressive disorder

BACKGROUND

Chemokines and their receptors regulate inflammatory processes in major depressive disorder (MDD). Here, we characterize the expression pattern of the C-C chemokine receptor 4 (CCR4) and its ligands CCL17 and CCL22 in MDD and its clinical relevance in predicting disease severity.

METHODS

Expression of CCR4 on peripheral blood lymphocytes and serum CCL17/CCL22 levels were measured using multiparameter flow cytometry and multiplex assays in 33 depressed inpatients at baseline (T0) and after 6-week multimodal treatment (T1) compared with 21 healthy controls (HC). Using stratified and correlation analysis, we examined the associations of CCR4-CCL17/CCL22 expression with depression severity and symptoms according to standard clinical rating scales and questionnaires. Additionally, we assessed whether polygenic risk score (PRS) for psychiatric disorders and chronotype are associated with disease status or CCR4-CCL17/CCL22 expression. Regression analysis was performed to assess the capacity of CCR4 and PRS in predicting disease severity.

RESULTS

Compared with HC, MDD patients showed significantly decreased CCR4 expression on T cells (T0 and T1), whereas CCL17/CCL22 serum levels were increased. Stratified and correlation analysis revealed an association of CCR4 expression on CD4⁺ T cells with depression severity as well as Beck Depression Inventory-II items including loss of pleasure, agitation and cognitive deficits. CCR4 expression levels on CD4⁺ T cells together with cross-disorder and chronotype PRS significantly predicted disease severity.

LIMITATIONS

This exploratory study with small sample size warrants future studies.

CONCLUSIONS

This newly identified CCR4-CCL17/CCL22 signature and its predictive capacity for MDD severity suggest its potential functional involvement in the pathophysiology of MDD.

CXCR6 positions cytotoxic T cells to receive critical survival signals in the tumor microenvironment

Cytotoxic T lymphocyte (CTL) responses against tumors are maintained by stem-like memory cells that self-renew but also give rise to effector-like cells. The latter gradually lose their anti-tumor activity and acquire an epigenetically fixed, hypofunctional state, leading to tumor tolerance. Here, we show that the conversion of stem-like into effector-like CTLs involves a major chemotactic reprogramming that includes the upregulation of chemokine receptor CXCR6. This receptor positions effector-like CTLs in a discrete perivascular niche of the tumor stroma that is densely occupied by CCR7+ dendritic cells (DCs) expressing the CXCR6 ligand CXCL16. CCR7+ DCs also express and trans-present the survival cytokine interleukin-15 (IL-15). CXCR6 expression and IL-15 trans-presentation are critical for the survival and local expansion of effector-like CTLs in the tumor microenvironment to maximize their anti-tumor activity before progressing to irreversible dysfunction. These observations reveal a cellular and molecular checkpoint that determines the magnitude and outcome of anti-tumor immune responses.

Expression of Th1/Th2 cell-related chemokine receptors on CD4+ lymphocytes under physiological conditions

INTRODUCTION

Chemokine receptors (CRs) and the prostaglandin D₂ receptor, CRTH2, have been used as surrogate markers for cytoplasmic Th1 and Th2 cytokines. The presence of regulatory T (Treg) and Th17 cells may affect the analysis of such surrogate markers, as they share several CRs with Th1 and Th2 cells. This study aimed to determine the optimal surrogate markers of Th1 and Th2 cells under physiological conditions.

METHODS

Surface and cytoplasmic markers of CD4⁺ peripheral lymphocytes were analyzed in healthy volunteers by flow cytometry. Th1, Th2, Th17, and Treg cells were identified as IFN-γ⁺ , IL-4⁺ IL-13⁺ , IL-17⁺ , and CD25⁺ FoxP3⁺ CD4⁺ lymphocytes, respectively.

RESULTS

The percentages of CXCR3⁺ and CCR5⁺ CD4⁺ lymphocytes clearly correlated with those of Th1 cells. The percentage of CRTH2⁺ CD4⁺ lymphocytes showed the closest correlation with that of Th2 cells. The percentages of Th2 cells correlated with those of CCR3⁺ or CCR8⁺ CD4⁺ lymphocytes, with the majority of CCR3⁺ and CCR8⁺ cells unlikely to be Th2 cells, themselves. The proportions of CCR4⁺ or CCR7⁺ CD4⁺ lymphocytes did not correlate with those of Th2 cells, possibly due to their expression on the surface of Treg and Th17 cells. Th2-related receptors were classified into three different groups for better understanding.

CONCLUSION

CXCR3 and CCR5 are useful markers of Th1 cells. With the exception of CCR4 and CCR7 expressed at measurable levels on Treg and Th17 cells, CRTH2 and CRs, CCR3, and CCR8 may be employed as surrogate markers of Th2 cells. The proposed surrogate markers may help physicians in interpreting the disease state.

Chemokines and their Receptors: Multifaceted Roles in Cancer Progression and Potential Value as Cancer Prognostic Markers

Chemokines are chemotactic cytokines that mediate immune cell chemotaxis and lymphoid tissue development. Recent advances have indicated that chemokines and their cognate receptors play critical roles in cancer-related inflammation and cancer progression. On the basis of these findings, the chemokine system has become a new potential drug target for cancer immunotherapy. In this review, we summarize the essential roles of the complex network of chemokines and their receptors in cancer progression. Furthermore, we discuss the potential value of the chemokine system as a cancer prognostic marker. The chemokine system regulates the infiltration of immune cells into the tumor microenvironment, which induces both pro- and anti-immunity and promotes or suppresses tumor growth and proliferation, angiogenesis, and metastasis. Increasing evidence indicates the promising prognostic value of the chemokine system in cancer patients. While CCL2, CXCL10, and CX3CL1/CX3CR1 can serve as favorable or unfavorable prognostic factors depending on the cancer types, CCL14 and XCL1 possess good prognostic value. Other chemokines such as CXCL1, CXCL8, and CXCL12 are poor prognostic markers. Despite vast advances in our understanding of the complex nature of the chemokine system in tumor biology, knowledge about the multifaceted roles of the chemokine system in different types of cancers is still limited. Further studies are necessary to decipher distinct roles within the chemokine system in terms of cancer progression and to validate their potential value in cancer prognosis.

Determination of cell expansion and surface molecule expression on anti-CD3/28 expanded CD4+ T cells

CD4⁺ T cell immunotherapy has potential for treatment in HIV-infected patients. A large number of expanded CD4⁺ T cells and confirmation of functional-related phenotypes are required for ensuring the successful outcomes of treatment. Freshly isolated CD4⁺ T cells from healthy donors were activated with anti-CD3/28-coated magnetic beads at different bead-to-cell ratios and cultured in the absence and presence of IL-2 supplementation for 3 weeks. Fold expansion, cell viability, growth kinetic and lymphocyte subset identities were determined. Data demonstrated that a 1:1 bead-to-cell ratio rendered the highest expansion of 1044-fold with 88% viability and 99.5% purity followed by the 2:1 and 0.5:1 ratios. No significant difference in proliferation and phenotypes was found between non-IL-2 and IL-2 supplementation groups. Several specific surface molecule expressions of the expanded cells including chemokine receptors, adhesion molecules, co-stimulatory molecules, activation molecules, maturation markers, cytokine receptors and other molecules were altered when compared to the unexpanded cells. This optimized expansion protocol using the 1:1 bead-to-cell ratio of anti-CD3/28-coated magnetic beads and culture condition without IL-2 supplementation provided the satisfactory yield with good reproducibility. Specific surface molecule expressions of the expanded cells presented potential roles in proliferation, differentiation, homeostasis, apoptosis and organ homing.

Chemokines Modulate Immune Surveillance in Tumorigenesis, Metastasis, and Response to Immunotherapy

Chemokines are small secreted proteins that orchestrate migration and positioning of immune cells within the tissues. Chemokines are essential for the function of the immune system. Accumulating evidence suggest that chemokines play important roles in tumor microenvironment. In this review we discuss an association of chemokine expression and activity within the tumor microenvironment with cancer outcome. We summarize regulation of immune cell recruitment into the tumor by chemokine-chemokine receptor interactions and describe evidence implicating chemokines in promotion of the "inflamed" immune-cell enriched tumor microenvironment. We review both tumor-promoting function of chemokines, such as regulation of tumor metastasis, and beneficial chemokine roles, including stimulation of anti-tumor immunity and response to immunotherapy. Finally, we discuss the therapeutic strategies target tumor-promoting chemokines or induce/deliver beneficial chemokines within the tumor focusing on pre-clinical studies and clinical trials going forward. The goal of this review is to provide insight into comprehensive role of chemokines and their receptors in tumor pathobiology and treatment.

Active secretion of CXCL10 and CCL5 from colorectal cancer microenvironments associates with GranzymeB+ CD8+ T-cell infiltration

Transcriptional expression of CXCR3 and CCR5 cognate chemokines correlate with CD8⁺ T-cell infiltration and prolonged survival in colorectal cancer (CRC). These findings were derived mainly from paraffin embedded tissues; thus little is known about the secretion pattern of CD8⁺ T-cell targeting chemokines from CRCs. Therefore, we developed and introduced a novel platform that assesses the immune mediators that are secreted from live excised tissues. Transcriptional profiling and unsupervised hierarchical clustering of 43 CRCs based on expression of genes that represent the adaptive immune response were used to predict tumors that are strong secretors of T-cell targeting chemokines. Secretion of these mediators were corroborated using flow cytometric analysis of T-cell lineage markers: CD4, CD8, IFN-γ, and GzmB. We demonstrate that stronger secretion of CXCL10 (CXCR3 ligand) and CCL5 (CCR5 ligand) and infiltration of GzmB⁺CD8⁺ cytotoxic T-lymphocytes (CTLs) and IFN-γ⁺CD4⁺ helper T-cells can be predicted by transcriptional profiling, and that CRCs with stronger T-cell immunity were proportionally skewed towards early TNM stages and lacked distant organ metastasis. Our study represents the first functional analysis of secreted immune mediators from CRCs beyond immunohistochemistry and real-time PCR, and observed active physiological interactions between the tumor cells and the immune cells in the tumor microenvironment.

Dietary long chain n-3 polyunsaturated fatty acids prevent allergic sensitization to cow's milk protein in mice

BACKGROUND

Cow's milk allergy is one of the most common food allergies in children and no treatment is available. Dietary lipid composition may affect the susceptibility to develop allergic disease.

OBJECTIVE

Assess whether dietary supplementation with long chain n-3 polyunsaturated fatty acids (n-3 LCPUFA) prevents the establishment of food allergy.

METHODS

Mice were fed a control or fish oil diet before and during oral sensitization with whey. Acute allergic skin response, serum immunoglobulins as well as dendritic cell (DC) and T cell subsets in mesenteric lymph nodes (MLN), spleen and/or small intestine were assessed.

RESULTS

The acute allergic skin response was reduced by more than 50% in sensitized mice fed the fish oil diet compared to the control diet. In addition, anti-whey-IgE and anti-whey-IgG1 levels were decreased in the fish oil group. Serum transfer confirmed that the Th2-type humoral response was suppressed since sera of fish oil fed sensitized mice had a diminished capacity to induce an allergic effector response in naïve recipient mice compared to control sera. Furthermore, the acute skin response was diminished upon passive sensitization in fish oil fed naïve recipient mice. In addition, the percentage of activated Th1 cells was reduced by fish oil in spleen and MLN of sham mice. The percentage of activated Th2 cells was reduced in both sham- and whey-sensitized mice. In contrast, whey-sensitized mice showed an increased percentage of CD11b+CD103+CD8α- DC in MLN in association with enhanced FoxP3+ regulatory T cells (Treg) in spleen and intestine of fish oil fed whey-sensitized mice compared to sham mice.

CONCLUSIONS AND CLINICAL RELEVANCE

Dietary n-3 LCPUFA largely prevented allergic sensitization in a murine model for cow's milk allergy by suppressing the humoral response, enhancing local intestinal and systemic Treg and reducing acute allergic symptoms, suggesting future applications for the primary prevention of food allergy.

International Union of Basic and Clinical Pharmacology. [corrected]. LXXXIX. Update on the extended family of chemokine receptors and introducing a new nomenclature for atypical chemokine receptors

Sixteen years ago, the Nomenclature Committee of the International Union of Pharmacology approved a system for naming human seven-transmembrane (7TM) G protein-coupled chemokine receptors, the large family of leukocyte chemoattractant receptors that regulates immune system development and function, in large part by mediating leukocyte trafficking. This was announced in Pharmacological Reviews in a major overview of the first decade of research in this field [Murphy PM, Baggiolini M, Charo IF, Hébert CA, Horuk R, Matsushima K, Miller LH, Oppenheim JJ, and Power CA (2000) Pharmacol Rev 52:145-176]. Since then, several new receptors have been discovered, and major advances have been made for the others in many areas, including structural biology, signal transduction mechanisms, biology, and pharmacology. New and diverse roles have been identified in infection, immunity, inflammation, development, cancer, and other areas. The first two drugs acting at chemokine receptors have been approved by the U.S. Food and Drug Administration (FDA), maraviroc targeting CCR5 in human immunodeficiency virus (HIV)/AIDS, and plerixafor targeting CXCR4 for stem cell mobilization for transplantation in cancer, and other candidates are now undergoing pivotal clinical trials for diverse disease indications. In addition, a subfamily of atypical chemokine receptors has emerged that may signal through arrestins instead of G proteins to act as chemokine scavengers, and many microbial and invertebrate G protein-coupled chemokine receptors and soluble chemokine-binding proteins have been described. Here, we review this extended family of chemokine receptors and chemokine-binding proteins at the basic, translational, and clinical levels, including an update on drug development. We also introduce a new nomenclature for atypical chemokine receptors with the stem ACKR (atypical chemokine receptor) approved by the Nomenclature Committee of the International Union of Pharmacology and the Human Genome Nomenclature Committee.

Suppressive effects of a novel CC chemokine receptor 4 antagonist on Th2 cell trafficking in ligand- and antigen-induced mouse models

CC chemokine receptor 4 (CCR4) has been implicated as a preferential marker for T helper type 2 (Th2) cells, and is believed to be involved in the pathology of allergic diseases by controlling Th2 cell trafficking into inflamed tissues. The objective of the study was to characterize the pharmacological properties of E0001-163, a novel CCR4 antagonist. E0001-163 was tested in both in vitro chemotaxis assays as well as in vivo mouse models of CCR4 ligand-induced air pouch and antigen-induced airway inflammation by utilizing in vitro-polarized Th2 cells. In vitro, E0001-163 inhibited migratory response of human Th2-polarized cells to CCL22, a CCR4 ligand, with an IC50 value of 11.9 nM. E0001-163 significantly suppressed CCL22-induced Th2 cell trafficking into mouse air pouch in a dose-dependent manner at doses of 3 and 10mg/kg, suggesting that E0001-163 has an inhibitory effect on CCR4-mediated T cell trafficking in vivo. In addition, E0001-163 partially decreased Th2 cell trafficking and the level of IL-4 in the lungs in Th2-tansferred and ovalbumin (OVA)-challenged mice. T cell trafficking involves multiple chemokine receptors both in acute and chronic phases, and our findings suggest that CCR4, together with other chemokine receptors, may be involved in Th2 cell trafficking under disease conditions.

Tissue specific heterogeneity in effector immune cell response

Post pathogen invasion, migration of effector T-cell subsets to specific tissue locations is of prime importance for generation of robust immune response. Effector T cells are imprinted with distinct “homing codes” (adhesion molecules and chemokine receptors) during activation which regulate their targeted trafficking to specific tissues. Internal cues in the lymph node microenvironment along with external stimuli from food (vitamin A) and sunlight (vitamin D₃) prime dendritic cells, imprinting them to play centre stage in the induction of tissue tropism in effector T cells. B cells as well, in a manner similar to effector T cells, exhibit tissue-tropic migration. In this review, we have focused on the factors regulating the generation and migration of effector T cells to various tissues along with giving an overview of tissue tropism in B cells.

Location, location, location: tissue-specific regulation of immune responses

Discovery of DCs and PRRs has contributed immensely to our understanding of induction of innate and adaptive immune responses. Activation of PRRs leads to secretion of inflammatory cytokines that regulate priming and differentiation of antigen-specific T and B lymphocytes. Pathogens enter the body via different routes, and although the same set of PRRs is likely to be activated, it is becoming clear that the route of immune challenge determines the nature of outcome of adaptive immunity. In addition to the signaling events initiated following innate-immune receptor activation, the cells of the immune system are influenced by the microenvironments in which they reside, and this has a direct impact on the resulting immune response. Specifically, immune responses could be influenced by specialized DCs, specific factors secreted by stromal cells, and also, by commensal microbiota present in certain organs. Following microbial detection, the complex interactions among DCs, stromal cells, and tissue-specific factors influence outcome of immune responses. In this review, we summarize recent findings on the phenotypic heterogeneity of innate and adaptive immune cells and how tissue-specific factors in the systemic and mucosal immune system influence the outcome of adaptive-immune responses.

Host and microbial factors in regulation of T cells in the intestine

The intestine is divided into specialized tissue areas that provide distinct microenvironments for T cells. Regulation of T-cell responses in the gut has been a major focus of recent research activities in the field. T cells in the intestine are regulated by the interplay between host and microbial factors. In the small intestine, retinoic acid (RA) is a major tissue factor that plays important roles in regulation of immune responses. In the large intestine, the influence of RA diminishes, but that of commensal bacterial products increases. RA, gut microbiota, and inflammatory mediators co-regulate differentiation, distribution, and/or effector functions of T cells. Coordinated regulation of immune responses by these factors promotes well-balanced immunity and immune tolerance. Dysregulation of this process can increase infection and inflammatory diseases.

An integrative computational systems biology approach identifies differentially regulated dynamic transcriptome signatures which drive the initiation of human T helper cell differentiation

Background

A proper balance between different T helper (Th) cell subsets is necessary for normal functioning of the adaptive immune system. Revealing key genes and pathways driving the differentiation to distinct Th cell lineages provides important insight into underlying molecular mechanisms and new opportunities for modulating the immune response. Previous computational methods to quantify and visualize kinetic differential expression data of three or more lineages to identify reciprocally regulated genes have relied on clustering approaches and regression methods which have time as a factor, but have lacked methods which explicitly model temporal behavior.

Results

We studied transcriptional dynamics of human umbilical cord blood T helper cells cultured in absence and presence of cytokines promoting Th1 or Th2 differentiation. To identify genes that exhibit distinct lineage commitment dynamics and are specific for initiating differentiation to different Th cell subsets, we developed a novel computational methodology (LIGAP) allowing integrative analysis and visualization of multiple lineages over whole time-course profiles. Applying LIGAP to time-course data from multiple Th cell lineages, we identified and experimentally validated several differentially regulated Th cell subset specific genes as well as reciprocally regulated genes. Combining differentially regulated transcriptional profiles with transcription factor binding site and pathway information, we identified previously known and new putative transcriptional mechanisms involved in Th cell subset differentiation. All differentially regulated genes among the lineages together with an implementation of LIGAP are provided as an open-source resource.

Conclusions

The LIGAP method is widely applicable to quantify differential time-course dynamics of many types of datasets and generalizes to any number of conditions. It summarizes all the time-course measurements together with the associated uncertainty for visualization and manual assessment purposes. Here we identified novel human Th subset specific transcripts as well as regulatory mechanisms important for the initiation of the Th cell subset differentiation.

T cell homing to epithelial barriers in allergic disease

Allergic inflammation develops in tissues that have large epithelial surface areas that are exposed to the environment, such as the lung, skin and gut. In the steady state, antigen-experienced memory T cells patrol these peripheral tissues to facilitate swift immune responses against invading pathogens. In at least two allergy-prone organs, the skin and the gut, memory T cells are programmed during the initial antigen priming to express trafficking receptors that enable them to preferentially home to these organs. In this review we propose that tissue-specific memory and inflammation-specific T cell trafficking facilitates the development of allergic disease in these organs. We thus review recent advances in our understanding of tissue-specific T cell trafficking and how regulation of T cell trafficking by the chemokine system contributes to allergic inflammation in mouse models and in human allergic diseases of the skin, lung and gut. Inflammation- and tissue-specific T lymphocyte trafficking pathways are currently being targeted as new treatments for non-allergic inflammatory diseases and may yield effective new therapeutics for allergic diseases.

Phenotype, effector function, and tissue localization of PD-1-expressing human follicular helper T cell subsets

Background

It is well established that PD-1 is expressed by follicular T cells but its function in regulation of human T helper cells has been unclear. We investigated the expression modality and function of PD-1 expressed by human T cells specialized in helping B cells.

Results

We found that PD-1-expressing T cells are heterogeneous in PD-1 expression. We identified three different PD-1-expressing memory T cell subsets (i.e. PD-1^{low (+)}, PD-1^{medium (++)}, and PD-1^{high (+++)} cells). PD-1⁺⁺⁺ T cells expressed CXCR5 and CXCR4 and were localized in the rim of germinal centers. PD-1⁺ or PD-1⁺⁺ cells expressed CCR7 and were present mainly in the T cell area or other parts of the B cell follicles. Utilizing a novel antigen density-dependent magnetic sorting (ADD-MS) method, we isolated the three T cell subsets for functional characterization. The germinal center-located PD-1⁺⁺⁺ T cells were most efficient in helping B cells and in producing IL-21 and CXCL13. Other PD-1-expressing T cells, enriched with Th1 and Th17 cells, were less efficient than PD-1⁺⁺⁺ T cells in these capacities. PD-1⁺⁺⁺ T cells highly expressed Ki-67 and therefore appear active in cell activation and proliferation in vivo. IL-2 is a cytokine important for proliferation and survival of the PD-1⁺⁺⁺ T cells. In contrast, IL-21, while a major effector cytokine produced by the PD-1-expressing T helper cells, had no function in generation, survival, or proliferation of the PD-1-expressing helper T cells at least in vitro. PD-1 triggering has a suppressive effect on the proliferation and B cell-helping function of PD-1⁺⁺⁺ germinal center T cells.

Conclusion

Our results revealed the phenotype and effector function of PD-1-expressing T helper cell subsets and indicate that PD-1 restrains the B cell-helping function of germinal center-localized T cells to prevent excessive antibody response.

CXCR3 in T cell function

CXCR3 is a chemokine receptor that is highly expressed on effector T cells and plays an important role in T cell trafficking and function. CXCR3 is rapidly induced on naïve cells following activation and preferentially remains highly expressed on Th1-type CD4(+) T cells and effector CD8(+) T cells. CXCR3 is activated by three interferon-inducible ligands CXCL9 (MIG), CXCL10 (IP-10) and CXCL11 (I-TAC). Early studies demonstrated a role for CXCR3 in the trafficking of Th1 and CD8 T cells to peripheral sites of Th1-type inflammation and the establishment of a Th1 amplification loop mediated by IFNγ and the IFNγ-inducible CXCR3 ligands. More recent studies have also suggested that CXCR3 plays a role in the migration of T cells in the microenvironment of the peripheral tissue and lymphoid compartment, facilitating the interaction of T cells with antigen presenting cells leading to the generation of effector and memory cells.

CXCR3 ligands: redundant, collaborative and antagonistic functions

CXCR3 is a chemokine receptor that is rapidly induced on naïve T cells following activation, and preferentially remains highly expressed on type-1 helper (Th1)-type CD4(+) T cells, effector CD8(+) T cells and innate-type lymphocytes, such as natural killer (NK) and NKT cells. CXCR3 is activated by three interferon (IFN)-γ-inducible ligands CXCL9 (monokine induced by gamma-interferon), CXCL10 (interferon-induced protein-10) and CXCL11 (interferon-inducible T-cell alpha chemoattractant). Although some studies have revealed that these ligands have redundant functions in vivo, other studies have demonstrated that the three CXCR3 ligands can also collaborate and even compete with each other. Differential regulation of the three ligands at specific times in defined anatomically restricted locations in vivo likely participates in the fine control of T-cell trafficking over the course of an immune response. Among the differences in regulation, CXCL10 is induced by a variety of innate stimuli that induce IFN-α/β as well as the adaptive immune cell cytokine IFN-γ, whereas CXCL9 induction is restricted to IFN-γ. In this review, we will discuss how the balance, timing and pattern of CXCR3 ligand expression appears to regulate the generation of effector T cells in the lymphoid compartment and subsequent migration into peripheral sites of Th1-type inflammation in which the CXCR3 ligands also then regulate the interactions and migratory behavior of effector T cells in an inflamed peripheral tissue.

Polarized dendritic cells as cancer vaccines: directing effector-type T cells to tumors

Ex vivo generation and antigen loading of dendritic cells (DCs) from cancer patients helps to bypass the dysfunction of endogenous DCs. It also allows to control the process of DC maturation and to imprint in maturing DCs several functions essential for induction of effective forms of cancer immunity. Recent reports from several groups including ours demonstrate that distinct conditions of DC generation and maturation can prime DCs for preferential interaction with different (effector versus regulatory) subsets of immune cells. Moreover, differentially-generated DCs have been shown to imprint different effector mechanisms in CD4(+) and CD8(+) T cells (delivery of "signal three") and to induce their different homing properties (delivery of "signal four"). These developments allow for selective induction of tumor-specific T cells with desirable effector functions and tumor-relevant homing properties and to direct the desirable types of immune cells to tumors.

An alternatively spliced CXCL16 isoform expressed by dendritic cells is a secreted chemoattractant for CXCR6+ cells

DC are professional APCs that initiate and regulate adaptive immune responses by interacting with naïve and memory T cells. Chemokines released by DC play an essential role in T cell recruitment and in the maintenance of antigen-specific T cell-DC conjugates. Here, we characterized the expression of the T cell-attracting chemokine CXCL16 by murine DC. We demonstrate that through alternative RNA splicing, DC not only express the previously characterized transmembrane CXCL16 isoform, which can be cleaved from the cell surface, but also a novel isoform lacking the transmembrane and cytoplasmic domains. Transfection of HEK293 cells shows that this novel isoform, termed CXCL16v, is not expressed on the cell membrane but is secreted as a protein of approximately 10 kDa. Quantitative PCR demonstrates that CXCL16v is broadly expressed in lymphoid and nonlymphoid tissues resembling the tissue distribution of DC. Indeed, CXCL16v mRNA is expressed significantly by spleen DC and BM-DC. Moreover, we show that mature DC have increased CXCL16v mRNA levels and express transmembrane and soluble CXCL16 proteins. Finally, we show that CXCL16v specifically attracts cells expressing the chemokine receptor CXCR6. Our data demonstrate that mature DC express secreted, transmembrane, and cleaved CXCL16 isoforms to recruit and communicate efficiently with CXCR6(+) lymphoid cells.

Independent regulation of chemokine responsiveness and cytolytic function versus CD8+ T cell expansion by dendritic cells

The ability of cancer vaccines to induce tumor-specific CD8+ T cells in the circulation of cancer patients has been shown to poorly correlate with their clinical effectiveness. In this study, we report that although Ags presented by different types of mature dendritic cells (DCs) are similarly effective in inducing CD8+ T cell expansion, the acquisition of CTL function and peripheral-type chemokine receptors, CCR5 and CXCR3, requires Ag presentation by a select type of DCs. Both "standard" DCs (matured in the presence of PGE2) and type 1-polarized DCs (DC1s) (matured in the presence of IFNs and TLR ligands, which prevent DCs "exhaustion") are similarly effective in inducing CD8+ T cell expansion and acquisition of CD45RO+IL-7R+IL-15R+ phenotype. However, granzyme B expression, acquisition of CTL activity, and peripheral tissue-type chemokine responsiveness are features exclusively exhibited by CD8+ T cells activated by DC1s. This advantage of DC1s was observed in polyclonally activated naive and memory CD8(+) T cells and in blood-isolated melanoma-specific CTL precursors. Our data help to explain the dissociation between the ability of cancer vaccines to induce high numbers of tumor-specific CD8+ T cells in the blood of cancer patients and their ability to promote clinical responses, providing for new strategies of cancer immunotherapy.

Selective addition of CXCR3(+) CCR4(-) CD4(+) Th1 cells enhances generation of cytotoxic T cells by dendritic cells in vitro

Increasing importance is being given to the stimulation of Th1 response in cancer immunotherapy because its presence can shift the direction of adaptive immune responses toward protective immunity. Based on chemokine receptor expression, CXCR3(+) CCR4(-) CD4(+) T cells as Th1-type cells were investigated its capacity in monocyte-derived dendritic cell (DC) maturation and polarization, and induction of antigen specific cytotoxic T lymphocytes (CTL) in vitro. The levels of IL-4, IL-5 and IL-10 were decreased to the basal level compared with high production of IFN-gamma, TNF-alpha, and IL-2 in CXCR3+CCR4-CD4+ T cells stimulated with anti-CD3 and anti-CD28 antibodies. Co-incubation of activated CD4(+) or CXCR3(+) CCR4-CD4(+) T cells with DC (CD4(+/) DC or CXCR3(+) CD4(+/) DC, respectively) particularly up-regulated IL-12 and CD80 expression compared with DC matured with TNF-a and LPS (mDC). Although there was no significant difference between the effects of the CXCR3(+) CCR4(-) CD4(+) and CD4(+) T cells on DC phenotype expression, CXCR3(+) CD4(+/) DC in CTL culture were able to expand number of CD8(+) T cells and increased frequencies of IFN-gamma secreting cells and overall cytolytic activity against tumor antigen WT-1. These results demonstrated that the selective addition of CXCR3(+) CCR4(-) CD4(+) T cells to CTL cultures could enhance the induction of CTLs by DC in vitro, and implicated on a novel strategy for adoptive T cell therapy.

Environmental cues, dendritic cells and the programming of tissue-selective lymphocyte trafficking

Lymphocytes are imprinted during activation with trafficking programs (combinations of adhesion and chemoattractant receptors) that target their migration to specific tissues and microenvironments. Cytokines contribute, but, for gut and skin, evolution has cleverly adapted external cues from food (vitamin A) and sunlight (ultraviolet-induced vitamin D3) to imprint lymphocyte homing to the small intestines and T cell migration into the epidermis. Dendritic cells are essential: they process the vitamins to their active metabolites (retinoic acid and 1,25(OH)(2)D3) for presentation with antigen to lymphocytes, and they help export environmental cues through lymphatics to draining lymph nodes, to program the trafficking and effector functions of naive T and B cells.

CXCR6-CXCL16 interaction in the pathogenesis of Juvenile Idiopathic Arthritis

In order to evaluate the role of CXCR6/CXCL16 in driving lymphocyte migration into inflamed joints of children with oligoarticular Juvenile Idiopathic Arthritis (JIA) we analysed CXCR6 expression and functional capability in lymphocytes from synovial fluid (SF) by flow cytometry, by real-time polymerase chain reaction (RT-PCR) and migration assays. Furthermore, CXCR6 and CXCL16 expression in synovial tissue (ST) was analysed by immunohistochemistry. T cells isolated from SF of patients with JIA expressed CXCR6 which was functionally active as shown by chemotactic assays. The same cells expressed CXCR3 and it exerted a migratory activity in response to CXCL10. CXCL16 and CXCR6 were intensively expressed on the synovium cells, respectively on macrophages, synoviocytes and endothelial cells and on lymphocytes, synoviocytes and endothelial cells. Taken together, these data suggest that CXCR6 and CXCR3 act coordinately with respective ligands and are involved in the pathophysiology of JIA-associated inflammatory processes.

Calcium signaling in dendritic cells by human or mycobacterial Hsp70 is caused by contamination and is not required for Hsp70-mediated enhancement of cross-presentation

Extracellular heat shock proteins (HSPs) can stimulate antigen-specific immune responses. Using recombinant human (rhu)Hsp70, we previously demonstrated that through complex formation with exogenous antigenic peptides, rhuHsp70 can enhance cross-presentation by antigen-presenting cells (APCs) resulting in stronger T cell stimulation. T cell stimulatory activity has also been described for mycobacterial (myc)Hsp70. MycHsp70-assisted T cell activation has been reported to act through the binding of mycHsp70 to chemokine receptor 5 (CCR5), calcium signaling, phenotypic maturation, and cytokine secretion by dendritic cells (DCs). We report that highly purified rhuHsp70 and mycHsp70 proteins both strongly enhance cross-presentation of exogenous antigens. Augmentation of cross-presentation was seen for different APCs, irrespective of CCR5 expression. Moreover, neither of the purified Hsp70 proteins induced calcium signals in APCs. Instead, calcium signaling activity was found to be caused by contaminating nucleotides present in Hsp70 protein preparations. These results refute the hypothesis that mycHsp70 proteins require CCR5 expression and calcium signaling by APCs for enhanced antigen cross-presentation for T cell stimulation.

The p110gamma isoform of phosphatidylinositol 3-kinase regulates migration of effector CD4 T lymphocytes into peripheral inflammatory sites

The role of PI-3K in leukocyte function has been studied extensively. However, the specific role of the p110gamma isoform of PI- 3K in CD4 T lymphocyte function has yet to be defined explicitly. In this study, we report that although p110gamma does not regulate antigen-dependent CD4 T cell activation and proliferation, it plays a crucial role in regulating CD4 effector T cell migration. Naïve p110gamma(-/-) CD4 lymphocytes are phenotypically identical to their wild-type (WT) counterparts and do not exhibit any defects in TCR-mediated calcium mobilization or Erk activation. In addition, p110gamma-deficient CD4 OT.II T cells become activated and proliferate comparably with WT cells in response to antigen in vivo. Interestingly, however, antigen-experienced, p110gamma-deficient CD4 OT.II lymphocytes exhibit dramatic defects in their ability to traffic to peripheral inflammatory sites in vivo. Although antigen-activated, p110gamma-deficient CD4 T cells express P-selectin ligand, beta2 integrin, beta1 integrin, CCR4, CXCR5, and CCR7 comparably with WT cells, they exhibit impaired F-actin polarization and migration in response to stimulation ex vivo with the CCR4 ligand CCL22. These findings suggest that p110gamma regulates the migration of antigen-experienced effector CD4 T lymphocytes into inflammatory sites during adaptive immune responses in vivo.

Engineered CCR5 superagonist chemokine as adjuvant in anti-tumor DNA vaccination

Chemokine receptors are promising targets for enhancing T-cell immunity and anti-cancer therapy. CCL5 is a potential adjuvant for DNA vaccination. We postulated that CCR5 superagonists could be even more effective. A CCR5 superagonist derived from natural CCL5 by directed in vitro evolution, namely 1P7, is used as a DNA vaccine adjuvant and expressed as fused chemokine-Ig (1P7-Ig). We show that OVA+1P7-Ig DNA co-inoculation induced higher frequencies of OVA-specific CD8 lymphocytes than OVA+CCL5-Ig or controls and gave an even better protection against tumor growth in a CCR5-dependant manner. Our results indicate that CCR5-superagonists may provide potent adjuvants for vaccines.

Tumor suppressive efficacy through augmentation of tumor-infiltrating immune cells by intratumoral injection of chemokine-expressing adenoviral vector

Our goal in the present study was to evaluate antitumor effects and frequency of tumor-infiltrating immune cells upon intratumoral injection of RGD fiber-mutant adenoviral vector (AdRGD) encoding the chemokines CCL17, CCL19, CCL20, CCL21, CCL22, CCL27, XCL1, and CX3CL1. Among eight kinds of chemokine-expressing AdRGDs, AdRGD-CCL19 injection most efficiently induced infiltration of T cells into established B16BL6 tumor parenchyma, whereas most of these T cells were perforin-negative in immunohistochemical analysis. Additionally, the growth of AdRGD-CCL19-injected tumors decreased only slightly as well as that of other tumors treated with each chemokine-expressing AdRGD, which indicated that accumulation of naive T cells in tumor tissue does not effectively damage the tumor cells. Tumor-bearing mice, in which B16BL6-specific T cells were elicited by dendritic cell-based immunization, demonstrated that intratumoral injection of AdRGD-CCL17, -CCL22, or -CCL27 could considerably suppress tumor growth and attract activated T cells. On the other hand, AdRGD-CCL19-injection in the immunized mice showed slight increase of tumor-infiltrating T cells compared to treatment using control vector. Collectively, although AdRGD-mediated chemokine gene transduction into established tumors would be very useful for augmentation of tumor-infiltrating immune cells, a combinational treatment that can systemically induce tumor-specific effector T cells is necessary for satisfactory antitumor efficacy.

CXCR6 is expressed on T cells in both T helper type 1 (Th1) inflammation and allergen-induced Th2 lung inflammation but is only a weak mediator of chemotaxis

Numerous chemokine receptors are increased in number on T cells in inflamed tissues. Our objective was to examine CXCR6 expression on lymphocytes during immune and inflammatory reactions and its potential for mediating T-cell recruitment. The cDNA for rat CXCR6 was cloned and monoclonal antibodies (mAbs) to CXCR6 were developed. CXCR6 was present on 4-6% of CD4 and CD8 T cells in blood, normal lymph nodes (LNs) and the spleen, primarily on memory T cells. In vitro antigen re-stimulation of LN T cells from animals with autoimmune arthritis and experimental autoimmune encephalomyelitis (EAE) increased the proportion of CXCR6(+) T cells to 35-50% and anti-T-cell receptor (TCR) activation to 60-80%. In vivo, after antigen challenge of LNs there was only a small increase in CXCR6(+) T cells on the lymphoblasts in the LNs, and a much higher percentage of T cells were CXCR6(+) in virus-induced peritoneal exudates (approximately 47%) and in allergen-induced lung inflammation (33%). Chemotaxis of CXCR6-expressing inflammatory T cells to CXCL16 was poor, but that to CXCL10 was robust. We conclude that few T cells in normal and antigen-challenged LNs are CXCR6(+), whereas a high proportion of in vitro activated T cells and T cells from inflammatory sites are CXCR6(+), but these cells migrate poorly to CXCL16. This suggests that CXCR6 may contribute to T-cell positioning and activation, rather than recruitment. CXCR6 is also expressed on T cells not only in T helper type 1 (Th1) inflammation (arthritis and EAE) but also, as shown here, in Th2 inflammation, where it is increased after allergen challenge.

FoxP3+ T cells undergo conventional first switch to lymphoid tissue homing receptors in thymus but accelerated second switch to nonlymphoid tissue homing receptors in secondary lymphoid tissues

Forkhead box P3 (FoxP3)-positive T cells are a specialized T cell subset for immune regulation and tolerance. We investigated the trafficking receptor switches of FoxP3(+) T cells in thymus and secondary lymphoid tissues and the functional consequences of these switches in migration. We found that FoxP3(+) T cells undergo two discrete developmental switches in trafficking receptors to migrate from primary to secondary and then to nonlymphoid tissues in a manner similar to conventional CD4(+) T cells as well as unique to the FoxP3(+) cell lineage. In the thymus, precursors of FoxP3(+) cells undergo the first trafficking receptor switch (CCR8/CCR9-->CXCR4-->CCR7), generating mostly homogeneous CD62L(+)CCR7(+)CXCR4(low)FoxP3(+) T cells. CXCR4 expression is regained in FoxP3(+) thymic emigrants in the periphery. Consistent with this switch, recent FoxP3(+) thymic emigrants migrate exclusively to secondary lymphoid tissues but poorly to nonlymphoid tissues. The FoxP3(+) thymic emigrants undergo the second switch in trafficking receptors for migration to nonlymphoid tissues upon Ag priming. This second switch involves down-regulation of CCR7 and CXCR4 but up-regulation of a number of memory/effector type homing receptors, resulting in generation of heterogeneous FoxP3(+) T cell subsets expressing various combinations of trafficking receptors including CCR2, CCR4, CCR6, CCR8, and CCR9. A notable difference between the FoxP3(+) and FoxP3(-) T cell populations is that FoxP3(+) T cells undergo the second homing receptor switch at a highly accelerated rate compared with FoxP3(-) T cells, generating FoxP3(+) T cells with unconventionally efficient migratory capacity to major nonlymphoid tissues.

Addition of GM-CSF to a peptide/KLH vaccine results in increased frequencies of CXCR3-expressing KLH-specific T cells

T-cell trafficking is determined by expression patterns of chemokine receptors. The chemokine receptor CXCR3 is expressed on a subpopulation of type 1 T cells and plays an important role for migration of T cells into inflamed and tumor tissues. Here, we studied the chemokine receptor expression on specific T cells generated against the neoantigen keyhole limpet hemocyanin (KLH) in patients who had been immunized in the context of a tumor peptide vaccination trial with or without the adjuvant granulocyte-macrophage colony-stimulating factor (GM-CSF). In patients immunized in the presence of GM-CSF the fraction of CXCR3(+) KLH-specific T cells was significantly higher than in patients immunized in the absence of GM-CSF (median 45 vs. 20%, P = 0.001). In contrast, the chemokine receptor CCR4, associated with migration to the skin was found in both cohorts on less than 10% of KLH-specific T cells. These results show that CXCR3 expression on vaccine-induced T cells can be modulated by modifying the local vaccine milieu.

Interaction between allelic variation in IL12B and CCR5 affects the development of AIDS: IL12B/CCR5 interaction and HIV/AIDS

OBJECTIVE

IL-12 is involved in immune surveillance and response that links the innate and adaptive arms of the immune system. Among its many effects, IL-12 increases the cell surface expression of the CCR5 co-receptor for R5 strains of HIV-1, which are predominantly involved in HIV-1 transmission and spread. In the present study we investigated the effect of epistasis between allelic variants of CCR5 and IL12B on the susceptibility to HIV-1 infection and HIV-1 disease progression.

METHODS

HIV-1-positive patients were genotyped for IL12Bpro from two groups of HIV-1 seroincident patients from Western Australia (n = 101 and 200), longitudinal clinical data were available for one of the Western Australian cohorts for a period of over 12 years and a group of seroprevalent individuals from Sydney (n = 112). A group of ethnically matched healthy volunteers (n = 200) was also genotyped as controls. Comparison of allele frequencies between HIV-1 patients and controls was performed to determine the influence on susceptibility to HIV-1 infection, and regression analysis was used to determine the influence on disease progression.

RESULTS

Individuals positive for CCR5Delta32 and who carry the IL12Bpro1.1 genotype were underrepresented across all three independent HIV-1-positive cohorts [odds ratio 0.5; 95% confidence interval (CI) 0.28-0.97; P = 0.038]. CCR5wt/wt and IL12Bpro2.2 individuals progressed to AIDS at a significantly faster rate than other CCR5 and IL12Bpro groups (hazards ratio 3.24; 95% CI 1.9-15.1; P = 0.002).

CONCLUSION

Epistatic interaction between allelic variants of CCR5 and IL12Bpro exert a significant influence on the clinical outcome of HIV-1 infection.

Expression of chemokine receptors on peripheral blood mononuclear cells of patients with immune-mediated neuropathies treated with intravenous immunoglobulins

Intravenous immunoglobulin (IVIg) is an efficacious treatment for immune-mediated neuropathies like Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating neuropathy (CIDP), and multifocal motor neuropathy (MMN). In the pathogenesis of immune-mediated neuropathies chemokines and their receptors play a crucial role. Using flow cytometry we examined whether IVIg modulates chemokine expression repertoires of T cells and monocytes. The expression of inflammatory chemokine receptors CCR1, CCR2, CCR4, CCR5, CCR6 and CXCR3 was investigated on circulating T-cell subsets, and CCR1, CCR2 and CCR5 on circulating monocytes before and after IVIg treatment in patients with immune-mediated neuropathies (MMN, n = 7; GBS, n = 1; CIDP, n = 2). Furthermore, the homing potential of T cells was analyzed by the expression of CCR7, a chemokine receptor known to be utilized by mature T cells to recirculate into secondary lymphoid organs. In contrast to studies in chronic heart failure, no differences in expression patterns before and after IVIg treatment of any of the investigated chemokine receptors were found. Furthermore, the proportion of CD45RO-positive CD4+ or CD8+ T-cell subsets was not changed by IVIg treatment. Thus, we concluded that modulation of the expression of chemokine receptors on circulating leukocytes by IVIg is not a mode of action in immune-mediated neuropathies.

Listeriolysin O derived from Listeria monocytogenes inhibits the effector phase of an experimental allergic rhinitis induced by ovalbumin in mice

Listeriolysin O (LLO) derived from Listeria monocytogenes is highly capable of inducing interleukin (IL)-12, IL-18 and interferon (IFN)-gamma, and facilitates the generation of Th1 cells. We have recently shown that recombinant LLO (rLLO) inhibits generation of ovalbumin (OVA)-specific Th2 immune response by skewing maturation of antigen-specific T cells into Th1 cells. In the present study, we investigated the effect of rLLO on the effector phase of Th2-dependent allergic rhinitis in BALB/c mice sensitized with OVA. In mice sensitized intraperitoneally and challenged intranasally with OVA, nasal allergic symptoms such as sneezing and nose-scratching were observed at a high frequency. A high titre of anti-OVA IgE antibody was detected in sera and a large number of eosinophils migrated into the nasal tissue. However, rLLO treatment during the intranasal challenge inhibited the allergic symptoms, production of anti-OVA IgE antibody and eosinophil infiltration. Though rLLO did not affect antigen-specific cytokine production from splenic CD4(+) T cells, rLLO significantly suppressed OVA-specific IL-4 and IL-5 production from nasal mononuclear cells. We further found that rLLO inhibited the recruitment of CD4(+) T cells in nasal mucosa, and diminished the transcription and cell surface expression of CCR4 on splenic CD4(+) T cells. Moreover, rLLO was able to inhibit the passive cutaneous anaphylaxis reaction mediated by anaphylactic antibodies (IgE and IgG(1)) and mast cells. Taken together, these data showed that rLLO suppresses the effector phase of allergic rhinitis by inhibition of Th2 cell recruitment to nasal mucosa and type I allergic reaction.

Interleukin 12 induces T-cell recruitment into the atherosclerotic plaque

CD4 T cells, through the release of cytokines as well as direct effector functions, have been implicated in promoting inflammation of the atherosclerotic plaque. Plaque-infiltrating CD4 T cells include a specialized subset of (CD4+)CD28- T cells that express a unique profile of regulatory receptors and are responsive to novel microenvironmental cues. Here we report that (CD4+)CD28- T cells, either isolated from the plaque tissue or from the blood of patients with acute coronary syndrome (ACS), spontaneously express interleukin (IL)-12 receptors, even in the absence of antigenic stimulation. (CD4+)CD28- IL-12R+ cells responded to IL-12 stimulation with the upregulation of the chemokine receptor CCR5 and the C-type lectin receptor CD161, both implicated in regulating tissue homing of effector T cells. IL-12 treatment of (CD4+)CD28- T cells enhanced their chemotaxis and transendothelial migration toward the chemokine CCL5. In vivo relevance for the role of IL-12 in regulating the recruitment of (CD4+)CD28- T cells into the atheroma was examined in human atheroma-SCID mouse chimeras. Exposure of nonstimulated (CD4+)CD28- T cells to IL-12 was sufficient to amplify T-cell accumulation within the inflamed plaque, and coadministration of anti-CCR5 antibodies blocked T-cell recruitment into the plaque. Thus, (CD4+)CD28- T cells functionally resemble NK cells, which have proinflammatory activity even in the unprimed state and respond to any IL-12-inducing host infection with a shift in tissue trafficking and accrual in inflammatory lesions.

Gut-associated lymphoid tissue-primed CD4+ T cells display CCR9-dependent and -independent homing to the small intestine

CD4(+) T-cell entry to the intestinal mucosa is central to the generation of mucosal immunity as well as chronic intestinal inflammation, yet the mechanisms regulating this process remain poorly defined. Here we show that murine small intestinal CD4(+) lamina propria lymphocytes express a heterogeneous but restricted array of chemokine receptors including CCR5, CCR6, CCR9, CXCR3, and CXCR6. CD4(+) T-cell receptor transgenic OT-II cells activated in mesenteric lymph nodes acquired a distinct chemokine receptor profile, including expression of CCR6, CCR9, and CXCR3 that was only partially reproduced in vitro after priming with mesenteric lymph node dendritic cells. A subset of these effector CD4(+) T cells, expressing CD69 and alpha(4)beta(7), entered the intestinal lamina propria and the majority of these cells expressed CCR9. CCR9(-/-) OT-II cells were disadvantaged in their ability to localize to the intestinal lamina propria; however, they were readily detected at this site and expressed alpha(4)beta(7), but little CCR2, CCR5, CCR6, CCR8, CCR10, CXCR3, or CXCR6. Thus, whereas CD4(+) T cells activated in gut-associated lymphoid tissue express a restricted chemokine receptor profile, including CCR9, targeting both CCR9-dependent and CCR9-independent entry mechanisms is likely to be important to maximally inhibit accumulation of these cells within the small intestinal mucosa.

The leukotriene B4 lipid chemoattractant receptor BLT1 defines antigen-primed T cells in humans

We have recently shown that the leukotriene B(4) (LTB(4))-BLT1 pathway is important in early effector T-cell recruitment in mouse models of inflammation. Here we characterize the phenotype and function of human peripheral blood BLT1(+) T cells in health and illustrate their involvement in asthma and acute infection. In healthy individuals, BLT1(+) T cells are a rare peripheral blood T-cell population enriched for the activation markers CD38 and HLA-DR. Compared with BLT1(-) T cells, a larger proportion of peripheral blood BLT1(+) T cells express the effector cytokines IFNgamma and IL-4 and inflammatory chemokine receptors, CCR1, CCR2, CCR6, and CXCR1. Consequently, in healthy individuals peripheral blood BLT1(+) T cells are a rare antigen-primed T-cell subset with unique phenotypic, migratory, and functional properties. BLT1 expression on T cells is tightly regulated by inflammation and only transiently expressed after naive T-cell activation by dendritic cells. Although rare in the peripheral blood of healthy individuals, BLT1(+) T cells are markedly increased in frequency in the peripheral blood in response to acute Epstein-Barr virus (EBV) infection and moderately increased in the airways of asymptomatic allergic asthmatics. Our studies provide novel insights into the LTB(4)-BLT1 lipid chemoattractant pathway in human T-cell responses, and how it may link innate and adaptive immunity.

Role for CXCR6 and its ligand CXCL16 in the pathogenesis of T-cell alveolitis in sarcoidosis

RATIONALE

Receptor expression dictates the spectrum of chemokine actions on immunocompetent cells. We have previously shown that the chemokine receptor CXCR3 is highly expressed by T-helper type 1 (Th1) cells infiltrating the lungs of patients with sarcoidosis.

OBJECTIVES

The evaluation of the role of Bonzo/CXCR6 and its ligand CXCL16 in the pathogenesis of sarcoidosis.

METHODS

Immunocompetent cells infiltrating sarcoid lung have been evaluated by flow cytometry, confocal microscopy, immunohistochemical and molecular analysis, and functional assays.

MAIN RESULTS

Th1 cells isolated from the bronchoalveolar lavage of patients with sarcoidosis and T-cell alveolitis coexpressed CXCR3 and CXCR6. Immunohistochemical analysis of lung specimens has shown that CXCR6+ T cells infiltrated lung interstitium surrounding the central core of the granuloma. The CXCR6 ligand CXCL16 was abundantly expressed by macrophages infiltrating sarcoid tissue and/or forming the granuloma core. From a functional point of view, sarcoid Th1 cells were able to respond to CXCL10 and CXCL16 in migratory assay. In vitro kinetic studies demonstrated that, although CXCR3 was rapidly induced by interleukin (IL)-15 and IL-18, CXCR6 induction was slow (8 d) and mainly regulated by IL-15.

CONCLUSIONS

T cells coexpressing CXCR3 and CXCR6 act coordinately with respective ligands and Th1 inflammatory cytokines in the alveolitic/granuloma phases of the disease.

Opposing Effects of CXCR3 and CCR5 Deficiency on CD8+ T Cell-Mediated Inflammation in the Central Nervous System of Virus-Infected Mice

T cells play a key role in the control of viral infection in the CNS but may also contribute to immune-mediated cell damage. To study the redundancy of the chemokine receptors CXCR3 and CCR5 in regulating virus-induced CD8+ T cell-mediated inflammation in the brain, CXCR3/CCR5 double-deficient mice were generated and infected intracerebrally with noncytolytic lymphocytic choriomeningitis virus. Because these chemokine receptors are mostly expressed by overlapping subsets of activated CD8+ T cells, it was expected that absence of both receptors would synergistically impair effector T cell invasion and therefore protect mice against the otherwise fatal CD8+ T cell-mediated immune attack. Contrary to expectations, the accumulation of mononuclear cells in cerebrospinal fluid was only slightly delayed compared with mice with normal expression of both receptors. Even more surprising, CXCR3/CCR5 double-deficient mice were more susceptible to intracerebral infection than CXCR3-deficient mice. Analysis of effector T cell generation revealed an accelerated antiviral CD8+ T cell response in CXCR3/CCR5 double-deficient mice. Furthermore, while the accumulation of CD8+ T cells in the neural parenchyma was significantly delayed in both CXCR3- and CXCR3/CCR5-deficient mice, more CD8+ T cells were found in the parenchyma of double-deficient mice when these were analyzed around the time when the difference in clinical outcome becomes manifest. Taken together, these results indicate that while CXCR3 plays an important role in controlling CNS inflammation, other receptors but not CCR5 also contribute significantly. Additionally, our results suggest that CCR5 primarily functions as a negative regulator of the antiviral CD8+ T cell response.

Gene therapy to manipulate effector T cell trafficking to tumors for immunotherapy

Strategies that generate tumor Ag-specific effector cells do not necessarily cure established tumors. We hypothesized that the relative efficiency with which tumor-specific effector cells reach the tumor is critical for therapy. We demonstrate in this study that activated T cells respond to the chemokine CCL3, both in vitro and in vivo, and we further demonstrate that expression of CCL3 within tumors increases the effector T cell infiltrate in those tumors. Importantly, we show that adenoviral gene transfer to cause expression of CCL3 within B16ova tumors in vivo increases the efficacy of adoptive transfer of tumor-specific effector OT1 T cells. We additionally demonstrate that such therapies result in endogenous immune responses to tumor Ags that are capable of protecting animals against subsequent tumor challenge. Strategies that modify the "visibility" of tumors have the potential to significantly enhance the efficacy of both vaccine and adoptive transfer therapies currently in development.

An innately interesting decade of research in immunology

"Nature has provided, in the white corpuscles as you call them-in the phagocytes as we call them-a natural means of devouring and destroying all disease germs. There is at bottom only one genuinely scientific treatment for all diseases, and that is to stimulate the phagocytes." So opined B.B. in G.B. Shaw's The Doctor's Dilemma in a dramatic restatement of a key portion of Ilya Metchnikoff's Nobel Prize address: "Whenever the organism enjoys immunity, the introduction of infectious microbes is followed by the accumulation of mobile cells, of white corpuscles of the blood in particular which absorb the microbes and destroy them. The white corpuscles and the other cells capable of doing this have been designated 'phagocytes,' (i.e., devouring cells) and the whole function that ensures immunity has been given the name of 'phagocytosis'". Based on these insights into the foundation of resistance to infectious disease, Metchnikoff was awarded the 1908 Nobel Prize in Physiology or Medicine together with Paul Ehrlich (Fig. 1). Although both were cited for discoveries in immunity, the contributions of the two men seem worlds apart. Ehrlich's studies did not deal with generic responses to infection, but rather with the highly specific nature of antibodies and their relationship to the cells producing them: "As the cell receptor is obviously preformed, and the artificially produced antitoxin only the consequence, i.e. secondary, one can hardly fail to assume that the antitoxin is nothing else but discharged components of the cell, namely receptors discharged in excess". But biological systems are just that-systems-and the parts need to work together. And so we arrive, a century later, at an appreciation for just how intimately related these two seemingly disparate aspects of host defense really are.

Chemoattractants and their receptors in homeostasis and inflammation

The study of leukocyte migration continues to provide new insights into the regulation of lymphocyte priming in secondary lymphoid organs and effector responses in inflamed tissues. Chemoattractant receptors have always been viewed as facilitators of cell movement into a tissue. This whole concept must now be revised with the discovery of sphingosine 1 phosphate receptors, which control cell exit from lymphoid tissues. The chemoattractants that regulate lymphoid tissue homing are usually different to those that regulate leukocyte recruitment to inflamed tissues. There is evidence, however, of inflammatory pathways of leukocyte recruitment in lymph nodes and, conversely of constitutive pathways in peripheral tissues. Finally, antagonists (or agonists) of chemoattractant receptors and their signalling pathways represent the most attractive strategy for the treatment of a wide range of inflammatory diseases, including allergy.

Impaired interleukin (IL)-4-associated generation of CCR4-expressing T cells in neonates with hereditary allergy risk

Reduced microbial exposure in early life may contribute to the increase of atopic diseases in 'westernized' societies but the underlying mechanisms remain elusive. The objective of this study was to examine how exposure to bacterial lipopolysaccharide (LPS) during early antigen encounter might influence the maturation of neonatal lymphoid cells, and to define possible differences in this respect between neonates with high risk of allergy due to a family history (FH(+)) and controls with no apparent hereditary risk (FH(-)). Cord blood mononuclear cells from the FH(+) or FH(-) group were stimulated with pure LPS or beta-lactoglobulin (beta-LG) in the presence of LPS. T cell expression of chemokine receptors CCR4 and CXCR3 was determined by flow cytometry and reverse transcription-polymerase chain reaction (RT-PCR). Cellular expression of interleukin (IL)-4 was analysed by quantitative RT-PCR, whereas interferon (IFN)-gamma was analysed by both quantitative RT-PCR and immunoassay. Stimulation with LPS, or beta-LG together with LPS, induced up-regulation of CCR4 (P < 0.05) and CXCR3 (P < 0.05). For CCR4, such up-regulation was related to the level of IL-4 produced by the same T cells (r(S) = 0.49, P = 0.03), while CXCR3 expression was negatively correlated with the IL-4 levels (r(S) = -0.56, P = 0.02). Compared with the FH(-) group, the FH(+) group showed a significantly lower capacity for generation of CCR4(+) T cells (mean percentage of total T cells: FH(+), 2.42%versus FH(-), 5.74%; P < 0.01), whereas induction of CXCR3 and IFN-gamma did not differ significantly between the two groups. When the immune system in early life encounters antigen together with LPS, the T cell potential for compartmentalized interaction with other immune cells might be increased by elevated CCR4- and CXCR3-expression levels. In neonates at hereditary allergy risk, this putative homeostatic mechanism could theoretically be jeopardized due to decreased up-regulation of CCR4. Conversely, Th1 responses to antigen in the presence of LPS did not appear to be reduced compared with controls.