A lymphocyte-specific CC chemokine, secondary lymphoid tissue chemokine (SLC), is a highly efficient chemoattractant for B cells and activated T cells

Cellular crosstalk of mesangial cells and tubular epithelial cells in diabetic kidney disease

Diabetic kidney disease (DKD) is a major cause of end-stage renal disease and imposes a heavy global economic burden; however, little is known about its complicated pathophysiology. Investigating the cellular crosstalk involved in DKD is a promising avenue for gaining a better understanding of its pathogenesis. Nonetheless, the cellular crosstalk of podocytes and endothelial cells in DKD is better understood than that of mesangial cells (MCs) and renal tubular epithelial cells (TECs). As the significance of MCs and TECs in DKD pathophysiology has recently become more apparent, we reviewed the existing literature on the cellular crosstalk of MCs and TECs in the context of DKD to acquire a comprehensive understanding of their cellular communication. Insights into the complicated mechanisms underlying the pathophysiology of DKD would improve its early detection, care, and prognosis. Video Abstract.

Nonclassical monocytes potentiate anti-tumoral CD8+ T cell responses in the lungs

CD8⁺ T cells drive anti-cancer immunity in response to antigen-presenting cells such as dendritic cells and subpopulations of monocytes and macrophages. While CD14⁺ classical monocytes modulate CD8⁺ T cell responses, the contributions of CD16⁺ nonclassical monocytes to this process remain unclear. Herein we explored the role of nonclassical monocytes in CD8⁺ T cell activation by utilizing E2-deficient (E2^-/-) mice that lack nonclassical monocytes. During early metastatic seeding, modeled by B16F10-OVA cancer cells injected into E2^-/- mice, we noted lower CD8⁺ effector memory and effector T cell frequencies within the lungs as well as in lung-draining mediastinal lymph nodes in the E2^-/- mice. Analysis of the myeloid compartment revealed that these changes were associated with depletion of MHC-II^loLy6C^lo nonclassical monocytes within these tissues, with little change in other monocyte or macrophage populations. Additionally, nonclassical monocytes preferentially trafficked to primary tumor sites in the lungs, rather than to the lung-draining lymph nodes, and did not cross-present antigen to CD8⁺ T cells. Examination of the lung microenvironment in E2^-/- mice revealed reduced CCL21 expression in endothelial cells, which is chemokine involved in T cell trafficking. Our results highlight the previously unappreciated importance of nonclassical monocytes in shaping the tumor microenvironment via CCL21 production and CD8⁺ T cell recruitment.

Nurse-like cells sequester B cells in chronic lymphocytic leukemia disorganized lymph nodes via an alternative production of CCL21

Stromal cell architecture is deeply altered in CLL lymph nodes.

CCL21, produced by leukemia-induced macrophages, improves retention and niching of malignant CCR7⁺ B cells in CLL lymph nodes.

Tumor microenvironment exerts a critical role in sustaining homing, retention, and survival of chronic lymphocytic leukemia (CLL) cells in secondary lymphoid organs. Such conditions foster immune surveillance escape and resistance to therapies. The physiological microenvironment is rendered tumor permissive by an interplay of chemokines, chemokine receptors, and adhesion molecules as well as by direct interactions between malignant lymphocytes and stromal cells, T cells, and specialized macrophages referred to as nurselike cells (NLCs). To characterize this complex interplay, we investigated the altered architecture on CLL lymph nodes biopsies and observed a dramatic loss of tissue subcompartments and stromal cell networks as compared with nonmalignant lymph nodes. A supplemental high density of CD68⁺ cells expressing the homeostatic chemokine CCL21 was randomly distributed. Using an imaging flow cytometry approach, CCL21 mRNA and the corresponding protein were observed in single CD68⁺ NLCs differentiated in vitro from CLL peripheral blood mononuclear cells. The chemokine was sequestered at the NLC membrane, helping capture of CCR7-high-expressing CLL B cells. Inhibiting the CCL21/CCR7 interaction by blocking antibodies or using therapeutic ibrutinib altered the adhesion of leukemic cells. Our results indicate NLCs as providers of an alternative source of CCL21, taking over the physiological task of follicular reticular cells, whose network is deeply altered in CLL lymph nodes. By retaining malignant B cells, CCL21 provides a protective environment for their niching and survival, thus allowing tumor evasion and resistance to treatment. These findings argue for a specific targeting or reeducation of NLCs as a new immunotherapy strategy for this disease.

C-C Chemokine Receptor 7 in Cancer

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

Chronic Pancreatitis and the Development of Pancreatic Cancer

Pancreatitis is a fibro-inflammatory disorder of the pancreas that can occur acutely or chronically as a result of the activation of digestive enzymes that damage pancreatic cells, which promotes inflammation. Chronic pancreatitis with persistent fibro-inflammation of the pancreas progresses to pancreatic cancer, which is the fourth leading cause of cancer deaths across the globe. Pancreatic cancer involves cross-talk of inflammatory, proliferative, migratory, and fibrotic mechanisms. In this review, we discuss the role of cytokines in the inflammatory cell storm in pancreatitis and pancreatic cancer and their role in the activation of SDF1α/CXCR4, SOCS3, inflammasome, and NF-κB signaling. The aberrant immune reactions contribute to pathological damage of acinar and ductal cells, and the activation of pancreatic stellate cells to a myofibroblast-like phenotype. We summarize several aspects involved in the promotion of pancreatic cancer by inflammation and include a number of regulatory molecules that inhibit that process.

Fractalkine enhances endometrial receptivity and activates iron transport towards trophoblast cells in an in vitro co-culture system of HEC-1A and JEG-3 cells

Endometrium receptivity and successful implantation require a complex network of regulatory factors whom production is strictly controlled especially at the implantation window. Many regulators like steroid hormones, prostaglandins, cytokines, extracellular matrix proteins and downstream cell signalling pathways are involved in the process of embryo-endometrium interaction. Our work reveals the effect of fractalkine (FKN), a unique chemokine on progesterone receptor, SOX-17 and NRF2 expressions in HEC-1A endometrial cell line. FKN activates fractalkine receptor signalling and the expression of SOX-17 through progesterone receptor in HEC-1A endometrial cells, and as a consequence it increases endometrial receptivity. Fractalkine also activates the NRF2-Keap-1 signal transduction pathway regulating the IL-6 and IL-1β cytokine productions, which increase endometrial receptivity, as well. The NRF2 transcription factor increases the expression of the iron exporter ferroportin in HEC-1A cells activating iron release towards JEG-3 trophoblast cells. The iron measurements show that iron content of endometrial cells decreases while heme concentration increases at FKN treatment. At the same time, the trophoblast cells show increased iron uptake and total iron content. Based on our results it seems that FKN enhances the establishment of endometrial receptivity and meanwhile it regulates the iron homeostasis of endometrium contributing to the iron availability of the trophoblast cells and the embryo.

Heparanase: Cloning, Function and Regulation

In 2019, we mark the 20th anniversary of the cloning of the human heparanase gene. Heparanase remains the only known enzyme to cleave heparan sulfate, which is an abundant component of the extracellular matrix. Thus, elucidating the mechanisms underlying heparanase expression and activity is critical to understanding its role in healthy and pathological settings. This chapter provides a historical account of the race to clone the human heparanase gene, describes the intracellular and extracellular function of the enzyme, and explores the various mechanisms regulating heparanase expression and activity at the gene, transcript, and protein level.

Fractalkine Regulates HEC-1A/JEG-3 Interaction by Influencing the Expression of Implantation-Related Genes in an In Vitro Co-Culture Model

Embryo implantation is a complex process regulated by a network of biological molecules. Recently, it has been described that fractalkine (CX3CL1, FKN) might have an important role in the feto-maternal interaction during gestation since the trophoblast cells express fractalkine receptor (CX3CR1) and the endometrium cells secrete fractalkine. CX3CR1 controls three major signalling pathways, PLC-PKC pathway, PI3K/AKT/NFκB pathway and Ras-mitogen-activated protein kinases (MAPK) pathways regulating proliferation, growth, migration and apoptosis. In this study, we focused on the molecular mechanisms of FKN treatment influencing the expression of implantation-related genes in trophoblast cells (JEG-3) both in mono-and in co-culture models. Our results reveal that FKN acted in a concentration and time dependent manner on JEG-3 cells. FKN seemed to operate as a positive regulator of implantation via changing the action of progesterone receptor (PR), activin receptor and bone morphogenetic protein receptor (BMPR). FKN modified also the expression of matrix metalloproteinase 2 and 9 controlling invasion. The presence of HEC-1A endometrial cells in the co-culture contributed to the effect of fractalkine on JEG-3 cells regulating implantation. The results suggest that FKN may contribute to the successful attachment and implantation of embryo.

T follicular helper cell heterogeneity: Time, space, and function

T follicular helper (Tfh) cells play a crucial role in orchestrating the humoral arm of adaptive immune responses. Mature Tfh cells localize to follicles in secondary lymphoid organs (SLOs) where they provide help to B cells in germinal centers (GCs) to facilitate immunoglobulin affinity maturation, class-switch recombination, and generation of long-lived plasma cells and memory B cells. Beyond the canonical GC Tfh cells, it has been increasingly appreciated that the Tfh phenotype is highly diverse and dynamic. As naive CD4⁺ T cells progressively differentiate into Tfh cells, they migrate through a variety of microanatomical locations to obtain signals from other cell types, which in turn alters their phenotypic and functional profiles. We herein review the heterogeneity of Tfh cells marked by the dynamic phenotypic changes accompanying their developmental program. Focusing on the various locations where Tfh and Tfh-like cells are found, we highlight their diverse states of differentiation. Recognition of Tfh cell heterogeneity has important implications for understanding the nature of T helper cell identity specification, especially the plasticity of the Tfh cells and their ontogeny as related to conventional T helper subsets.

Women who had appendectomy have increased risk of systemic lupus erythematosus: a nationwide cohort study

The appendix is involved in immune function, and an appendectomy may alter the immune system. Studies evaluating the relationship between previous appendectomy and the risk of systemic lupus erythematosus (SLE) are lacking. This nationwide cohort study investigated the incidence and risk of SLE in patients who underwent appendectomy. Patients aged > 20 years who received appendectomy from 2000 to 2011 were identified from the National Health Insurance Research Database and assigned to the appendectomy cohort. Patients without appendectomy were randomly selected from the NHIRD and assigned to the control cohort; they were frequency matched to each study patient at a 4:1 ratio by sex, age, and index year. All patients were followed until SLE diagnosis, withdrawal from the National Health Insurance program, or the end of 2011. We used Cox models to estimate the hazard ratio (HR) and 95% confidence interval (CI) to compare the risk of SLE between the appendectomy and control cohorts. From 23.74 million people in the cohort, 80,582 patients undergoing appendectomy and 323,850 patients without appendectomy were followed for 723,438 and 2,931,737 person-years, respectively. The appendectomy cohort had a 2.04-fold higher risk of SLE than the control cohort (adjusted HR = 2.04, 95% CI = 1.52-2.76). Women aged ≤ 49 years who underwent appendectomy had a 2.27-fold higher risk of SLE than the corresponding controls (adjusted HR = 2.27, 95% CI = 1.62-3.19). Women aged ≤ 49 years who underwent appendectomy have a significantly higher risk of SLE.

CCR7 Is Important for Mesangial Cell Physiology and Repair

The homeostatic chemokine receptor CCR7 serves as key molecule in lymphocyte homing into secondary lymphoid tissues. Previous experiments from our group identified CCR7 also to be expressed by human mesangial cells. Exposing cultured human mesangial cells to the receptor ligand CCL21 revealed a positive effect on these cells regarding proliferation, migration, and survival. In the present study, we localized CCR7 and CCL21 during murine nephrogenesis. Analyzing wild-type and CCR7 deficient (CCR7^-/-) mice, we observed a retarded glomerulogenesis during renal development and a significantly decreased mesangial cellularity in adult CCR7^-/- mice, as a consequence of less mesangial cell proliferation between embryonic day E17.5 and week 5 postpartum. Cell proliferation assays and cell-wounding experiments confirmed reduced proliferative and migratory properties of mesangial cells cultured from CCR7^-/- kidneys. To further emphasize the role of CCR7 as important factor for mesangial biology, we examined the chemokine receptor expression in rats after induction of a mesangioproliferative glomerulonephritis. Here, we demonstrated for the first time that extra- and intraglomerular mesangial cells that were CCR7-negative in control rats exhibited a strong CCR7 expression during the phase of mesangial repopulation and proliferation.

The immunology of the vermiform appendix: a review of the literature

This literature review assesses the current knowledge about the immunological aspects of the vermiform appendix in health and disease. An essential part of its immunological function is the interaction with the intestinal bacteria, a trait shown to be preserved during its evolution. The existence of the appendiceal biofilm in particular has proved to have a beneficial effect for the entire gut. In assessing the influence of acute appendicitis and the importance of a normally functioning gut flora, however, multiple immunological aspects point towards the appendix as a priming site for ulcerative colitis. Describing the immunological and microbiotical changes in the appendix during acute and chronic inflammation of the appendix, this review suggests that this association becomes increasingly plausible. Sustained by the distinct composition of cells, molecules and microbiota, as well as by the ever more likely negative correlation between the appendix and ulcerative colitis, the idea of the appendix being a vestigial organ should therefore be discarded.

The chemotactic interaction between CCL21 and its receptor, CCR7, facilitates the progression of pancreatic cancer via induction of angiogenesis and lymphangiogenesis

BACKGROUND

In this study, we report the influence of CCL21 and its receptor, CCR7, on the progression of pancreatic cancer and illuminates the correlation between the CCL21/CCR7 axis and the angiogenesis and lymphangiogenesis of pancreatic adenocarcinoma (PAC).

METHODS

A total of 30 patients with pancreatic cancer was involved in the current study. The expression of CCL21 and CCR7 in cancerous tissues, paracancerous tissues and normal pancreas were investigated using real-time PCR, Western blot and immunohistochemistry, respectively. In addition, we assessed microvessel density (MVD) and microlymphatic vessel density (MLVD) in tumor tissues using immunohistochemistry.

RESULTS

Compared to paracancerous tissues and normal pancreas, CCL21 expression in cancerous tissues was detected at a significantly low level. In contrast, the CCR7 expression was considerably higher in cancerous tissues than in normal pancreas and paracancerous tissues. Additionally, a significant correlation between the expression pattern of the CCL21/CCR7 axis and clinicopathological features, such as lymph node metastasis, was identified. Furthermore, we found that CCL21 expression was significantly associated with MVD but not significantly associated with MLVD, while CCR7 expression was significantly associated with MLVD but not significantly associated with MVD.

CONCLUSIONS

The chemotactic interaction between CCR7 and its ligand, CCL21, may be a critical event during progression in pancreatic cancer, and its underlying mechanism may be induction of angiogenesis and lymphangiogenesis regulated by this chemotactic interaction.

Comparative Transcriptomic Analysis of Rectal Tissue from Beef Steers Revealed Reduced Host Immunity in Escherichia coli O157:H7 Super-Shedders

Super-shedder cattle are a major disseminator of E. coli O157:H7 into the environment, and the terminal rectum has been proposed as the primary E. coli O157:H7 colonization site. This study aimed to identify host factors that are associated with the super-shedding process by comparing transcriptomic profiles in rectal tissue collected from 5 super-shedder cattle and 4 non-shedder cattle using RNA-Seq. In total, 17,859 ± 354 genes and 399 ± 16 miRNAs were detected, and 11,773 genes were expressed in all animals. Fifty-eight differentially expressed (DE) genes (false discovery rate < 0.05) including 11 up-regulated and 47 down-regulated (log 2 (fold change) ranged from -5.5 to 4.2), and 2 up-regulated DE miRNAs (log 2 (fold change) = 2.1 and 2.5, respectively) were identified in super-shedders compared to non-shedders. Functional analysis of DE genes revealed that 31 down-regulated genes were potentially associated with reduced innate and adaptive immune functions in super-shedders, including 13 lymphocytes membrane receptors, 3 transcription factors and 5 cytokines, suggesting the decreased key host immune functions in the rectal tissue of super-shedders, including decreased quantity and migration of immune cells such as lymphocytes, neutrophils and dendritic cells. The up-regulation of bta-miR-29d-3p and the down regulation of its predicted target gene, regulator of G-protein signaling 13, suggested a potential regulatory role of this miRNA in decreased migration of lymphocytes in super-shedders. Based on these findings, the rectal tissue of super-shedders may inherently exhibit less effective innate and adaptive immune protection. Further study is required to confirm if such effect on host immunity is due to the nature of the host itself or due to actions mediated by E. coli O157:H7.

CCR7 regulates cell migration and invasion through MAPKs in metastatic squamous cell carcinoma of head and neck

Migration and invasion of tumor cells are essential prerequisites for the formation of metastasis in malignant diseases. Previously, we have reported that CC chemokine receptor 7 (CCR7) regulates the mobility of squamous cell carcinoma of head and neck (SCCHN) cells through several pathways, such as integrin and cdc42. In this study, we investigated the connection between CCR7 and mitogen-activated protein kinase (MAPK) family members, and their influence on cell invasion and migration in metastatic SCCHN cells. Western blotting, immunostaining and fluorescence microcopy were used to detect the protein expression and distribution of MAPKs, and the Migration assay, Matrigel invasion assay and wound-healing assay to detect the role of MAPKs in CCR7 regulating cell mobility. To analyze the correlation between CCR7 and MAPK activity and clinicopathological factors immunohistochemical staining was emplyed. The results showed stimulation of CCL19 and the activation of CCR7 could induce ERK1/2 and JNK phosphorylation, while it had no efect on p38. After activation, ERK1/2 and JNK promoted E-cadherin low expression and Vimentin high expression. The MAPK pathway not only mediated CCR7 induced cell migration, but also mediated invasion speed. The immunohistochemistry results showed that CCR7 was correlated with the phosphorylation of ERK1/2 and JNK in SCCHN, and these molecules were all associated with lymph node metastasis. Therefore, our study demonstrates that MAPK members (ERK1/2 and JNK) play a key role in CCR7 regulating SCCHN metastasis.

Chemokine receptor 7 enhances cell chemotaxis and migration of metastatic squamous cell carcinoma of head and neck through activation of matrix metalloproteinase-9

The mechanisms leading to squamous cell carcinoma of head and neck (SCCHN) metastasis are not fully understood. Although evidence shows that the chemokine receptor 7 (CCR7) and its ligand CCL19 may regulate tumor dissemination, their role is not clearly defined in SCCHN. Matrix metalloproteinases break consisting of tissue barrier to the surrounding tissue invasion and metastasis by destroying the balance of matrix degradation of the basement membrane of tumor cells and extracellular matrix (ECM). We used chemotaxis and migration assays, western blotting, gelatin zymography, actin polymerization assay, immunofluorescence staining and immunohistochemical analysis to explore whether MMP-9 can be activated by CCL19 (CCR7's ligand) and its role in SCCHN. The experiments were performed in the metastatic SCCHN cell line PCI-37B after pre-incubation of the cells with CCL19 and SB-3CT (inhibitor of MMP-9). Our results demonstrated that CCR7 favors PCI-37B cell chemotaxis and migration, upregulation of MMP-9 protein and motivates the activity of MMP-9 protein, induces reorganization of the actin cytoskeleton and upregulation of MMP-9 protein. SB-3CT can block all these effects. Collectively, our data indicated that CCR7 regulates cell chemotaxis and migration via MMP-9 in metastatic SCCHN, and these results provide a basis for new strategies in preventing metastases of SCCHN.

Elevated concentrations of CCR7 ligands in patients with eosinophilic pneumonia

BACKGROUND

Previous studies suggest that dendritic cells and macrophages play an important role in inflammation of eosinophilic pneumonia. The mechanism of dendritic cell and macrophage accumulation into the lung, however, is unknown. Here, we hypothesized that CCR7 ligands, CCL19 and CCL21, contribute to the accumulation of dendritic cells and alveolar macrophages in the inflamed lung of patients with eosinophilic pneumonia.

METHODS

Concentrations of the CCR7 ligands as well as CCL16, CCL17 and CCL22 in the bronchoalveolar lavage fluid of 53 patients with eosinophilic pneumonia, 29 patients with sarcoidosis, 18 patients with idiopathic pulmonary fibrosis and 12 healthy volunteers were measured by enzyme-linked immunosorbent assay. Cell sources of CCR7 ligands and CCR7-expressing cells in the bronchoalveolar lavage fluid were evaluated by immunocytochemistry.

RESULTS

CCL19 and CCL21 levels in the bronchoalveolar lavage fluid were significantly higher in patients with eosinophilic pneumonia than in controls. Levels of CCL19, but not CCL21, were statistically correlated with the levels of CCL16, CCL17 and CCL22 in patients with eosinophilic pneumonia. Immunocytochemistry revealed CCL19 expression in dendritic cells, macrophages and T-lymphocytes harvested from patients with eosinophilic pneumonia, and CCR7 expression in dendritic cells and macrophages. Levels of CCL19, but not CCL21, were significantly decreased after remission in patients with eosinophilic pneumonia. After provocation tests, CCL19 levels were elevated in all patients with eosinophilic pneumonia.

CONCLUSIONS

These findings indicate that CCL19 rather than CCL21 may contribute to the accumulation of dendritic cells and macrophages in the inflamed lungs of patients with eosinophilic pneumonia.

The anti-tumor effect and increased tregs infiltration mediated by rAAV-SLC vector

To explore the anti-tumor effect and immune mechanism mediated by a new recombinant adeno-associated virus (rAAV) encoding secondary lymphoid tissue chemokine (SLC) mature peptide gene. AAV Helper-Free system was used for rAAV-SLC package. The anti-tumor effect of SLC was detected by bearing tumor established from Hepal-6 cells both in C57BL/6J and nude mice. Flow cytometry analysis and IHC for Tumor-infiltrating T cells and CD11c+DCs were also investigated to explore the immunological mechanism. rAAV-SLC was successfully packaged in AAV293 cells and transfected Hepal-6 tumor cells at high efficiency. The anti-tumor effect was demonstrated by less tumor weight and longer survival outcome. Coincident with the anti-tumor response, local elaboration of SLC within the tumor bed elicited a heavy infiltration of CD4+, CD8+T cells and CD11c+ dendritic cells into the tumor sites. More importantly, there was higher infiltration of Foxp3+ regulatory T cells (Tregs). Local elaboration of SLC mediated by rAAV-SLC has strong T cell mediated anti-tumor effect. The study also suggested that Tregs in the tumor microenvironment tampered the anti-tumor effect.

CC chemokine receptors and chronic inflammation--therapeutic opportunities and pharmacological challenges

Chemokines are a family of low molecular weight proteins with an essential role in leukocyte trafficking during both homeostasis and inflammation. The CC class of chemokines consists of at least 28 members (CCL1-28) that signal through 10 known chemokine receptors (CCR1-10). CC chemokine receptors are expressed predominantly by T cells and monocyte-macrophages, cell types associated predominantly with chronic inflammation occurring over weeks or years. Chronic inflammatory diseases including rheumatoid arthritis, atherosclerosis, and metabolic syndrome are characterized by continued leukocyte infiltration into the inflammatory site, driven in large part by excessive chemokine production. Over years or decades, persistent inflammation may lead to loss of tissue architecture and function, causing severe disability or, in the case of atherosclerosis, fatal outcomes such as myocardial infarction or stroke. Despite the existence of several clinical strategies for targeting chronic inflammation, these diseases remain significant causes of morbidity and mortality globally, with a concomitant economic impact. Thus, the development of novel therapeutic agents for the treatment of chronic inflammatory disease continues to be a priority. In this review we introduce CC chemokine receptors as critical mediators of chronic inflammatory responses and explore their potential role as pharmacological targets. We discuss functions of individual CC chemokine receptors based on in vitro pharmacological data as well as transgenic animal studies. Focusing on three key forms of chronic inflammation--rheumatoid arthritis, atherosclerosis, and metabolic syndrome--we describe the pathologic function of CC chemokine receptors and their possible relevance as therapeutic targets.

T cells that promote B-Cell maturation in systemic autoimmunity

Follicular helper T (Tfh) cells play an essential role in helping B cells generate antibodies upon pathogen encounters. Such T-cell help classically occurs in germinal centers (GCs) located in B-cell follicles of secondary lymphoid organs, a site of immunoglobulin affinity maturation and isotype switching. B-cell maturation also occurs extrafollicularly, in the red pulp of the spleen and medullary cords in lymph nodes, with plasma cell formation and antibody production. Development of extrafollicular foci (EF) in T-cell-dependent (TD) immune responses is reliant upon CD4(+) T cells with characteristics of Tfh cells. Pathogenic autoantibodies, arising from self-reactive B cells having undergone somatic hypermutation with affinity selection and class switching within GCs and EF, are major contributors to the end-organ injury in systemic autoimmunity. B cells maturing to produce autoantibodies in systemic autoimmune diseases, like those in normal immune responses, largely require T-helper cells. This review highlights Tfh cell development as an introduction to a more in-depth discussion of human Tfh cells and blood borne cells with similar features and the role of these cells in promotion of systemic autoimmunity.

Follicular helper T cells in immunity and systemic autoimmunity

Follicular helper T (T(FH)) cells are essential for B-cell maturation and immunoglobulin production after immunization with thymus-dependent antigens. Nevertheless, the development and function of T(FH) cells have been less clearly defined than classic CD4(+) effector T-cell subsets, including T-helper-1 (T(H)1), T(H)2 and T(H)17 cells. As such, our understanding of the genesis of T(FH) cells in humans and their role in the development of autoimmunity remains incomplete. However, evidence from animal models of systemic lupus erythematosus (SLE) and patients with systemic autoimmune diseases suggests that these cells are necessary for pathogenic autoantibody production, in a manner analogous to their role in promotion of B-cell maturation during normal immune responses. In this Review, I discuss the findings that have increased our knowledge of T(FH)-cell development and function in normal and aberrant immune responses. Such information might improve our understanding of autoimmune diseases, such as SLE, and highlights the potential of T(FH) cells as therapeutic targets in these diseases.

Regulatory effect of cannabinoid receptor agonist on chemokine-induced lymphocyte chemotaxis

Cannabinoids elicit biological responses through two types of specific receptors, CB1 and CB2. Immune cells including naïve B-lymphocytes are known to selectively express peripheral cannabinoid receptors, CB2. Although the immunosuppressive effects of cannabinoids have become widely known, the mechanisms underlying their effects are not well understood. In this study, we demonstrated that splenic lymphocytes migrated toward a synthetic cannabinoid receptor agonist, WIN55,212-2. There is an optimal concentration range for induction of lymphocyte migration and a high dose fails to induce cell migration. Furthermore, a high dose of WIN55,212-2 significantly inhibited CXCL12-induced chemotaxis of lymphocytes. The inhibitory effect was transient and reversible. The inhibition was also observed when purified B-lymphocytes were used for CXCL12-induced chemotaxis. These results provide novel information regarding the cellular mechanisms underlying the effects of cannabinoids on the immune system.

Regulatory effect of lysophosphatidic acid on lymphocyte migration

Lysophosphatidic acid (LPA) is a lipid mediator that is known to exhibit chemotactic activity toward a variety of cancer cells. However, its effect on the immune system has not been studied extensively. Another lipid mediator, sphingosine-1-phosphate (S1P), has been shown to influence lymphocyte recirculation by regulating lymphocyte egress from lymphoid organs. In this study, we found that LPA inhibits spontaneous migration of mouse splenic lymphocytes through a chemorepulsive effect. We also demonstrated that LPA inhibits chemokine CCL21-induced lymphocyte migration. This inhibitory effect on CCL21-induced migration was observed for both T and B cells. The involvement of a receptor, LPA(1), LPA(2) or LPA(3), in the inhibition of the CCL21-induced migration was confirmed with a synthetic agonist, oleyl thiophosphate. Considering that the signaling by CCL21 through cognate receptor CCR7 contributes to lymphocyte homing and dendritic cell trafficking to lymph nodes, LPA may play a role as a key regulator of these processes. The inhibitory effect of LPA is in remarkable contrast to the effect of S1P receptor signaling, which is known to potentiate lymphocyte chemotaxis involving CCR7.

FOXO1, T-cell trafficking and immune responses

Efficient T-cell adaptive immune response require a faultless coordination between migration of naive T-cells into secondary lymphoid organs and critical biological outcomes driven by antigen such as cell division and cell differentiation into effector and memory cells. Recent works have shown that the phosphoinositide 3-kinase (PI3K) pathway could govern several of these processes. In this control, transcriptional factors of the Forkhead box O (FoxO) family, in particular FOXO1, a downstream effector of PI3K, appears to play a major role by coordinating both cellular proliferation of T-cells after antigen recognition and expression of homing molecules essential for their trafficking in the body.

SLC/CCR7 stimulates the proliferation of BMDCs by the pNF-kappaB p65 pathway

The chemokine receptor CCR7 is highly expressed in dendritic cells (DCs), T cells, and other immune effector cells. One of the high-affinity ligand that can bind to CCR7 is the secondary lymphoid tissue chemokine (SLC). The SLC/CCR7 axis plays an important role in the immune system by inducing the chemotaxis and migration of immune effector cells. In this study, we examined the effect of SLC at different concentrations (0, 50, 100, 200, 300, and 400 ng/mL) on the proliferation of bone-marrow-derived dendritic cells (BMDCs). ELC (CCL19), another high-affinity ligand for CCR7, was used as the control at the same time. We found that SLC directly stimulated the proliferation of BMDCs and enhanced the antigen-presenting function and CCR7 expression. Western blot analysis showed that pNF-kappaBp65 was involved in this mechanism. We also found that the NF-kappaB inhibitor PDTC could specifically block the proliferation and CCR7 expression of BMDCs induced by SLC or ELC (200 ng/mL). The results suggested that there were cross-talk signals between the chemotaxis and proliferation of BMDCs involving the SLC/CCR7 axis.

The chemokine CXCL13 is a key regulator of B cell recruitment to the cerebrospinal fluid in acute Lyme neuroborreliosis

Background

The chemokine CXCL13 is known to dictate homing and motility of B cells in lymphoid tissue and has been implicated in the formation of ectopic lymphoid tissue in chronic inflammation. Whether it influences B cell trafficking during acute infection, is largely unclear. In previous studies, we showed that (I) CXCL13 levels are markedly increased in the B cell-rich cerebrospinal fluid (CSF) of patients with acute Lyme neuroborreliosis (LNB), and (II) CXCL13 is released by monocytes upon recognition of borrelial outer surface proteins by Toll-like receptor 2. Here, we assessed the role of CXCL13 - in comparison to other chemokines - in the recruitment of B cells to the CSF of patients with acute LNB.

Methods

Measurement of chemokines was done by ELISA. B cells were isolated from whole blood using magnetic cell separation (MACS). For migration experiments, a modified Boyden chamber assay was used and the migrated B cells were further analysed by FACS. The migration was inhibited either by preincubation of the CSF samples with neutralizing antibodies, heating to 60°C, removal of proteins >3 kDa, or by pre-treatment of the B cells with pertussis toxin. The principal statistical tests used were one-way analysis of variance and Bonferroni test (chemokine measurements) as well as paired Student's t-test (migration experiments).

Results

Measurements of chemokine levels revealed an increase in three of the four known major B cell chemoattractants CXCL13, CCL19 and CXCL12 in LNB CSF. The CXCL13 CSF:serum ratio, as a measure of the chemotactic gradient, was substantially higher than that of CCL19 and CXCL12. Moreover, the chemotactic activity of LNB CSF was reduced up to 56% after preincubation with a neutralizing CXCL13 antibody, while combined preincubation with antibodies against CXCL13, CCL19, and CXCL12 did not lead to further reduction. Since treatment with pertussis toxin, heating to 60°C, and removal of proteins >3 kDa abrogated the chemotactic activity, further not yet identified chemokines seem to be involved in B cell recruitment to LNB CSF.

Conclusion

Combined, our study suggests a key role of CXCL13 in B cell migration to sites of infection as shown here for the CSF of LNB patients.

Mammalian target of rapamycin (mTOR) is involved in the survival of cells mediated by chemokine receptor 7 through PI3K/Akt in metastatic squamous cell carcinoma of the head and neck

Metastatic squamous cell carcinoma (SCC) of the head and neck expresses chemokine receptor 7 (CCR7), which activates phosphoinositide-3 kinase (PI3K) to promote invasion and survival of SCC cells in the head and neck. We hypothesised that mammalian target of rapamycin (mTOR) may be the downstream molecule of the CCR7-PI3K pathway. Results have shown that interaction between CCR7 and its ligand CCL19 induces the phosphorylation of mTOR and its target p70s6k. This phosphorylation is abolished by inhibition of CCR7 and PI3K/Akt, indicating that mTOR is involved in the CCR7-PI3K cascade. The inhibitors of mTOR and CCR7-PI3K also lead to a significant increase in CCL19-induced death, apoptosis, and cell-cycle arrest of metastatic SCC cells in the head and neck. Taken together, our data indicate the important part played by mTOR in CCR7-induced survival of such SCC cells.

Impaired interleukin-8 chemokine secretion by staphylococcus aureus-activated epithelium and T-cell chemotaxis in cystic fibrosis

Staphylococcus aureus is frequently isolated from lungs of patients with cystic fibrosis (CF). Upon lung infection with S. aureus, airway epithelial cells (AEC) produce high levels of chemokines that enhance T-cell chemotaxis. Although the number of lymphocytes is increased in the airways and bronchoalveolar lavage fluid of patients with CF, the mechanisms responsible for their accumulation and the role of S. aureus in this process are largely unknown. This study investigated early S. aureus impact on chemokine secretion by CF epithelial cells and chemotaxis of CF T cells. CF and non-CF AEC were grown in a cell culture model and apically stimulated with S. aureus. Supernatants were quantified for chemokine secretions and assayed for T-cell chemotaxis. CF AEC secreted constitutively larger amounts of IL-8, GROalpha, MIG, MIP-3beta, and MCP-1 than non-CF epithelial cells. S. aureus interaction with epithelial cells increased chemokine production by non-CF cells but had no effect on CF cells. Chemotaxis of T cells derived from patients with CF was greater than that of T cells from subjects without CF. Moreover, there were more CF T cells expressing CXCR1 as compared with non-CF T cells. Under our experimental conditions, inhibition of IL-8 or its receptor CXCR1 resulted in a considerable decrease in T-cell chemotaxis (up to 80%). These data suggest that IL-8 and its receptor CXCR1 are key players in the chemotaxis of CF T cells and could be used as targets to develop therapies for CF.

Salmonella typhimurium engineered to produce CCL21 inhibit tumor growth

Intravenously-applied bacteria tend to accumulate in tumors and can sporadically lead to tumor regression. Systemic administration of attenuated Salmonella typhimurium is safe and has shown no significant adverse effects in humans. The purpose of this study was to test the hypothesis that engineering S. typhimurium to express a chemokine, CCL21, would increase anti-tumor activity. We engineered an attenuated strain of S. typhimurium to produce the chemokine CCL21. Attenuated S. typhimurium expressing CCL21 significantly inhibited the growth of primary tumors and pulmonary metastases in preclinical models of multi-drug-resistant murine carcinomas, while control bacteria did not. Histological analysis of tumors showed marked inflammatory cell infiltrates in mice treated with CCL21-expressing but not control bacteria. Levels of cytokines and chemokines known to be induced by CCL21 [e.g., interferon-gamma (INFgamma), CXCL9, and CXCL10] were significantly elevated in tumors of mice treated with CCL21-expressing but not control S. typhimurium. The anti-tumor activity was found to be dependent on CD4- and CD8-expressing cells, based on antibody-mediated in vivo immuno-depletion experiments. Anti-tumor activity was achieved without evidence of toxicity. In summary, chemokine-expressing, attenuated bacteria may provide a novel approach to cancer immunotherapy for effective and well-tolerated in vivo delivery of immunomodulatory proteins.

Impaired CD4 and CD8 T cell phenotype and reduced chemokine secretion in recent-onset type 1 diabetic children

Although the role of the T cell-mediated autoimmune reaction in type 1 diabetes (T1D) is conclusive, studies including data from human circulating CD4(+) and CD8(+) lymphocytes subsets during the disease onset and posterior development are scarce. Further, chemokines and chemokine receptors are key players in the migration of pathogenic T cells into the islets of non-obese diabetic mice developing T1D, but few studies have investigated these markers in human T1D patients. We studied the expression of T helper 1 (Th1)- and Th2-associated chemokine receptors, and the two isoforms of CD45 leucocyte antigen on CD4(+) and CD8(+) lymphocytes from T1D and healthy children, as well as the secretion of chemokines in cell supernatants in peripheral blood mononuclear cells. Our results showed increased expression of CCR7 and CD45RA and reduced CD45RO on CD8(+) cells among recent-onset T1D patients. The percentages of CD4(+) cells expressing CXC chemokine receptor 3 (CXCR3), CXCR6 and CCR5, and the secretion of interferon-gamma-induced protein-10, monocyte chemoattractant protein-1, macrophage inflammatory protein (MIP)-1alpha and MIP-1beta was lower among diabetics. Low expression of Th1-associated receptors and secretion of chemokines, together with an increased amount of CD8(+) cells expressing CD45RA and CCR7 in T1D patients therefore might represent suboptimal Th function in T1D, leading to impaired T cytotoxic responses or alternatively reflect a selective recruitment of Th1 cells into the pancreas.

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

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

Matrix metalloproteinase-9 is up-regulated by CCL21/CCR7 interaction via extracellular signal-regulated kinase-1/2 signaling and is involved in CCL21-driven B-cell chronic lymphocytic leukemia cell invasion and migration

B-cell chronic lymphocytic leukemia (B-CLL) progression is frequently accompanied by clinical lymphadenopathy, and the CCL21 chemokine may play an important role in this process. Indeed, CCR7 (the CCL21 receptor), as well as matrix metalloproteinase-9 (MMP-9), are overexpressed in infiltrating B-CLL cells. We have studied whether MMP-9 is regulated by CCL21 and participates in CCL21-dependent migration. CCL21 significantly increased B-CLL MMP-9 production, measured by gelatin zymography. This was inhibited by blocking extracellular signal-regulated kinase-1/2 (ERK1/2) activity or by cell transfection with CCR7-siRNA. Accordingly, CCL21/CCR7 interaction activated the ERK1/2/c-Fos pathway and increased MMP-9 mRNA. CCL21-driven B-CLL cell migration through Matrigel or human umbilical vein endothelial cells (HUVEC) was blocked by anti-CCR7 antibodies, CCR7-siRNA transfection, or the ERK1/2 inhibitor U0126, as well as by anti-MMP-9 antibodies or tissue inhibitor of metalloproteinase 1 (TIMP-1). These results strongly suggest that MMP-9 is involved in B-CLL nodal infiltration and expand the roles of MMP-9 and CCR7 in B-CLL progression. Both molecules could thus constitute therapeutic targets for this disease.

Rofecoxib has Different Effects on Chemokine Production in Colorectal Cancer Cells and Tumor Immune Splenocytes

Cyclooxygenase-2 (COX-2) is overexpressed in colon tumors. Its main product is the immunosuppressive prostaglandin PGE2 that aids tumor immune escape. In this study, we analyzed mechanisms of action of the COX-2 inhibitor rofecoxib on the immune response to colorectal cancer in an animal model. The murine colorectal cancer cell line MC26, and splenocytes from BALB/c mice immune to irradiated MC26 cells, were incubated with rofecoxib or PGE2. In MC26 cells, 100 nM rofecoxib caused a complete abrogation of PGE2 production and inhibited cell proliferation. Splenocytes from tumor immune mice showed a 300% (P<0.01) increase in proliferation in response to irradiated MC26 cells, amplified to 450% (P<0.01) by 1 microM rofecoxib (n=3). MC26 cells incubated with 1 microM rofecoxib showed increased gene expression of CCL3, CCL5, and CCL20 (P<0.01). enzyme-linked immunosorbent assay tests also showed increased production of CCL5 and CCL20 (P<0.01). PGE2 reversed this effect causing a 40% reduction in chemokine gene expression (n=3). In contrast, splenocytes from naive BALB/c mice stimulated with irradiated MC26 cells had only a marginal chemokine response to rofecoxib. PGE2 caused a 50% down-regulation of CCL5 and CCL20 at the gene level (n=2) and 30% and 40% reduction of CCL3, CCL4, CCL5, and CCL20 at the protein level (n=2). Hence rofecoxib has a 2-fold effect upon the immune response to MC26 cells, by enhancing production of chemokines chemotactic for dendritic cells and also reducing PGE2-mediated inhibition of lymphoproliferation. Together, these may be sufficient for an effective TH1-mediated antitumor response. Rofecoxib may have potential as an addition to existing immunotherapy strategies.

Synergistic antitumor effect of chemotactic-prostate tumor-associated antigen gene-modified tumor cell vaccine and anti-CTLA-4 mAb in murine tumor model

In this study, we demonstrate that an effective immune response against prostate tumors in mouse tumor model can be elicited using a strategy that combines CTLA-4 blockade and pSLC-3P-Fc-modified tumor cell vaccine (named B16F10-SLC-3P-Fc). Treatment of B16F10-3P-bearing mice resulted in a significant reduction in tumor incidence as assessed 2 months after treatment. In vivo Ab depletion confirmed that the antitumor effect was primarily CD8+ T cells and CD4+ T lymphocytes were required for the induction of CD8+ CTL response in B16F10-SLC-3P-Fc+anti-CTLA-4 mAb-immunized mice. Moreover, mice that were cured of an established tumor were protected against a rechallenge with the same tumor for at least 4 months, suggesting the generation of memory responses. Adoptive transfer experiments further indicate that antitumor reactivity can be transferred to naïve mice by splenocytes. These findings demonstrate that this combinatorial treatment can elicit a potent anti-tumor immune response and suggest potential of this approach for treatment of prostate cancer.

Attenuated Salmonella engineered to produce human cytokine LIGHT inhibit tumor growth

Intravenously administered bacteria reportedly accumulate in tumors. Furthermore, systemic administration of attenuated Salmonella typhimurium has little or no significant side-effects in humans. Consequently, we engineered such bacteria to improve their oncolytic activity by stably inserting a gene encoding LIGHT, a cytokine known to promote tumor rejection. Unlike control bacteria, attenuated S. typhimurium expressing LIGHT inhibited growth of primary tumors, as well as the dissemination of pulmonary metastases, in various mouse tumor models employing murine carcinoma cell lines in immunocompetent mice. Antitumor activity was achieved without significant toxicity and was associated with infiltration of inflammatory cells and dependent on the LIGHT receptors, herpes virus entry mediator (HVEM), and lymphotoxin-beta receptor (LTbetaR). These findings provide evidence that nonvirulent bacteria can be exploited as targeting vehicles for local generation of therapeutic proteins in tumors.

Local expression of secondary lymphoid tissue chemokine delivered by adeno-associated virus within the tumor bed stimulates strong anti-liver tumor immunity

Development of an effective antitumor immune response depends on the appropriate interaction of effector and target cells. Thus, the expression of chemokines within the tumor may induce a more potent antitumor immune response. Secondary lymphoid tissue chemokine (SLC) is known to play a critical role in establishing a functional microenvironment in secondary lymphoid tissues. Its capacity to attract dendritic cells (DCs) and colocalize them with T cells makes it a good therapeutic candidate against cancer. In this study, we used SLC as a treatment for tumors established from a murine hepatocellular carcinoma model. SLC was encoded by recombinant adeno-associated virus (rAAV), a system chosen for the low host immunity and high efficiency of transduction, enabling long-term expression of the gene of interest. As a result, rAAV-SLC induced a significant delay of tumor progression, which was paralleled by a profound infiltration of DCs and activated CD4(+) T cells and CD8(+) T cells (CD3(+) CD69(+) cells) into the tumor site. In addition, rAAV-SLC treatment was also found to reduce tumor growth in nude mice, most likely due to inhibition of neoangiogenesis. In conclusion, local expression of SLC by rAAV represents a promising approach to induce immune-mediated regression of malignant tumors.

More than chemotaxis: a new anti-tumor DC vaccine modified by rAAV2-SLC

Secondary lymphoid tissue chemokine (SLC) is strongly expressed in secondary lymphoid organs. Its ability to facilitate chemotaxis of both dendritic cells (DC) and T cells makes it a promising candidate for cancer therapy. In this study, we modified a BMDC vaccine by incorporating the SLC mature peptide gene. The efficacy of this vaccine was evaluated using a mouse hepatocellular carcinoma (HCC) model, with rAAV2 as the gene delivery vector. The rAAV2 encoding SLC (rAAV2-SLC) transfected immature BMDCs at high efficiency and the anti-tumor effects of SLC gene modified BMDCs (rAAV2-SLC/BMDC) were evaluated. In addition, rAAV2-SLC/BMDC vaccine injected directly into tumors attracted more CD4(+) and CD8(+) T lymphocytes into tumors and showed stronger anti-tumor effects than footpad delivery. Moreover, we found that the phenotypic expression of MHC II, the secretion of IL-12 and IFN-gamma, and T cell stimulation were increased in vitro following treatment with rAAV2-SLC/BMDC vaccine and these responses were inhibited by PTX. In vivo, PTX also inhibited the anti-tumor effects of the vaccine. The results suggest that the expression of SLC by rAAV2-SLC/BMDC plays more than a chemotactic role in anti-tumor responses, thus these studies further demonstrate that SLC has potential to be valuable in cancer therapy.

Crk-Associated Substrate Lymphocyte Type Is Required for Lymphocyte Trafficking and Marginal Zone B Cell Maintenance

The lymphocyte-specific Cas family protein Cas-L (Crk-associated substrate lymphocyte type) has been implicated to function in lymphocyte movement, mediated mainly by integrin signaling. However, its physiological role is poorly understood. In this study we analyzed the function of Cas-L in lymphocytes using gene-targeted mice. The mutant mice showed a deficit of marginal zone B (MZB) cells and a decrease of cell number in secondary lymphoid organs. An insufficient chemotactic response and perturbed cell adhesion were observed in Cas-L-deficient lymphocytes, suggesting that the aberrant localization was responsible for the deficit of MZB cells. Moreover, we found that lymphocyte trafficking was altered in Cas-L-deficient mice, which gave a potential reason for contraction of secondary lymphoid tissues. Thus, Cas-L affects homeostasis of MZB cells and peripheral lymphoid organs, which is considered to be relevant to impaired lymphocyte migration and adhesion.

Disparate lymphoid chemokine expression in mice and men: no evidence of CCL21 synthesis by human high endothelial venules

T-cell homing to secondary lymphoid tissues generally depends on chemokine-induced firm adhesion in high endothelial venules (HEVs) and is primarily mediated through the CC chemokine receptor 7 (CCR7) on lymphocytes. The CCR7 ligand designated CCL21 is considered the most important trigger because it appears constitutively expressed by murine HEVs. Surprisingly, when we analyzed human tissues, no CCL21 mRNA could be detected in HEVs. In fact, CCL21 mRNA was only expressed in extravascular T-zone cells and lymphatics, whereas immunostaining revealed CCL21 protein within HEVs. This suggests that T-cell recruitment to human lymphoid tissues depends on the transcytosis of lymphoid chemokines through HEV cells because there is at present no evidence of alternative chemokine production in these cells that could explain the attraction of naive T lymphocytes.

Synergistic antitumor effect by coexpression of chemokine CCL21/SLC and costimulatory molecule LIGHT

To establish a more efficient treatment for immunotherapy against solid tumors, we have evaluated the antitumor effect by coexpression of a chemokine CCL21/secondary lymphoid tissue chemokine and a costimulatory molecule LIGHT in colon carcinoma C26. C26 cells expressing either CCL21 or LIGHT exhibited a significantly reduced tumor growth in vivo, and mice inoculated with these cells showed a prolonged survival, but eventually all these mice died. In contrast, C26 cells expressing both CCL21 and LIGHT exhibited a minimal tumor growth in vivo, and all these mice survived healthily with a tumor remission and consequently acquired a strong protective immunity. A markedly increased infiltration of mature dendritic cells (DCs), and CD8(+) T cells was observed in the tumor mass, and their spleen cells showed a greatly enhanced cytotoxic T lymphocyte (CTL) activity against C26 tumor and interferon (IFN)-gamma production. Neutralization of IFN-gamma or depletion of CD8(+) or CD4(+) T cells significantly reduced the antitumor activity. These results suggest that the combined treatment with CCL21 and LIGHT is able to induce a synergistic antitumor effect to eradicate tumor completely by greatly enhancing tumor-infiltration of lymphocytes including mature DCs and CD8(+) T cells, resulting in markedly augmented CTL activity and IFN-gamma production.

A novel model for lymphocytic infiltration of the thyroid gland generated by transgenic expression of the CC chemokine CCL21

Lymphocytic infiltrates and lymphoid follicles with germinal centers are often detected in autoimmune thyroid disease (AITD), but the mechanisms underlying lymphocyte entry and organization in the thyroid remain unknown. We tested the hypothesis that CCL21, a chemokine that regulates homeostatic lymphocyte trafficking, and whose expression has been detected in AITD, is involved in the migration of lymphocytes to the thyroid. We show that transgenic mice expressing CCL21 from the thyroglobulin promoter (TGCCL21 mice) have significant lymphocytic infiltrates, which are topologically segregated into B and T cell areas. Although high endothelial venules expressing peripheral lymph node addressin were frequently observed in the thyroid tissue, lymphocyte recruitment was independent of L-selectin or lymphotoxin-alpha but required CCR7 expression. Taken together, these results indicate that CCL21 is sufficient to drive lymphocyte recruitment to the thyroid, suggest that CCL21 is involved in AITD pathogenesis, and establish TGCCL21 transgenic mice as a novel model to study the formation and function of lymphoid follicles in the thyroid.

Blocking Programmed Death-1 Ligand-PD-1 Interactions by Local Gene Therapy Results in Enhancement of Antitumor Effect of Secondary Lymphoid Tissue Chemokine

The negative signal provided by interactions of programmed death-1 (PD-1) and its ligands, costimulatory molecules PD-L1 (also B7-H1) and PD-L2 (also B7-DC), is involved in the mechanisms of tumor immune evasion. In this study, we found that this negative signal was also involved in immune evasion in tumor immunotherapy. When we used different doses of a constructed eukaryotic expression plasmid, pSLC, which expresses functional murine secondary lymphoid tissue chemokine (SLC, CCL21), to treat BALB/c mice inoculated with H22 murine hepatoma cells, the inhibitory effect was enhanced along with the increase of pSLC dosage. Unexpectedly, however, the best complete inhibition rate of tumor was reached when pSLC was used at the dosage of 50 microg but not 100 or 200 microg. RT-PCR and real-time PCR revealed that both PD-L1 and PD-L2 genes were expressed in tumor and vicinal muscle tissues of tumor-bearing mice and the expression level was significantly increased if a higher dosage of pSLC was administered. We then constructed a eukaryotic expression plasmid (pPD-1A) that expresses the extracellular domain of murine PD-1 (sPD-1). sPD-1 could bind PD-1 ligands, block PD-Ls-PD-1 interactions, and enhance the cytotoxicity of tumor-specific CTL. Local gene transfer by injection of pPD-1A mediated antitumor effect and improved SLC-mediated antitumor immunity. The combined gene therapy with SLC plus sPD-1 did not induce remarkable autoimmune manifestations. Our findings provide a potent method of improving the antitumor effects of SLC and possibly other immunotherapeutic methods by local blockade of negative costimulatory molecules.