Search

Lung cancer remains the most common cause of cancer death worldwide with approximately 85% of patients having non-small cell lung cancer (NSCLC). Checkpoint blockade immunotherapy has evolved the current treatment landscape with robust and durable responses in approximately 20% of patients with progressive, locally advanced, or metastatic NSCLC, as well as in treatment-na�ve advanced disease. Inefficient tumor antigen presentation, diminished T cell infiltration into tumor and LKB1-inactivating mutations contribute to the mechanisms of resistance to programmed death-ligand 1 (PD-L1) or programmed cell death protein 1 (PD-1) blockade in NSCLC. One approach to overcome this immunosuppressive tumor microenvironment (TME) is to utilize in situ vaccination with gene-modified functional antigen presenting cells (APCs) to enhance tumor antigen presentation and promote tumor-specific T cell activation. Here I address two potential therapies: 1) CCL21-genetically engineered dendritic cells (CCL21-DC) and 2) CXCL9/10-genetically engineered dendritic cells (CXCL9/10-DC), which are shown to remodel the tumor immune microenvironment and promote an anti-tumor immune response. In addition, the pre-clinical studies detailed here investigate the mechanisms of how these potential therapies can potentiate checkpoint blockade immunotherapy. These preclinical models serve as a platform to enhance our understanding of the molecular mechanisms of response and resistance to immunotherapy. In addition, these studies provide insights to anti-tumor immunity mediated by in situ DC vaccination and may in turn facilitate the improvement of novel vaccine therapies. The final chapter addresses the pressing need for the development of innovative approaches to detect and intercept lung cancer at its earliest stages of development. Using spatial multiplex immunofluorescence, this chapter highlights the efforts to understand the immune landscape in the tumor microenvironment associated with early-stage lung carcinogenesis and provides further understanding of the mechanism of lung cancer evolution. Research focusing on the development of novel strategies for cancer interception prior to the progression to advanced stages will potentially lead to a paradigm shift in the treatment of lung cancer and have a major impact on clinical outcomes.

Chemokines form a large family composed primarily of small secreted cytokine proteins that coordinate leukocyte trafficking by binding to seven-transmembrane (7TM) domain receptors. Chemokines mediate normal host defense and tissue repair; however, they may also support pathological immune responses, including chronic inflammation, autoimmunity, and cancer. The chemokine system is also a major target for immune system evasion or exploitation by pathogens (e.g., human immunodeficiency virus [HIV] and Plasmodium vivax). Increasingly, additional immunological and nonimmunological chemokine functions are being recognized. The nonimmunological functions can be beneficial, as in embryogenesis, or harmful, as in cancer. WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome is the only known mendelian condition caused by mutations in a chemokine or chemokine receptor (the receptor CXCR4). Two chemokine receptor antagonists have been approved by the U.S. Food and Drug Administration (FDA) so far: maraviroc, a CCR5 antagonist, used in the treatment of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), and plerixafor, a CXCR4 antagonist, approved for hematopoietic stem cell mobilization for transplantation in cancer. This chapter will expand on these and other basic principles and clinical correlates of chemokine regulation of the immune system.

Leukotriene B4 (LTB4) receptor 1 (BLT1) is a chemotactic G protein-coupled receptor expressed by leukocytes, such as granulocytes, macrophages, and activated T cells. Although there is growing evidence that BLT1 plays crucial roles in immune responses, its role in dendritic cells remains largely unknown. Here, we identified novel DC subsets defined by the expression of BLT1, namely, BLT1hi and BLT1lo DCs. We also found that BLT1hi and BLT1lo DCs differentially migrated toward LTB4 and CCL21, a lymph node-homing chemoattractant, respectively. By generating LTB4-producing enzyme LTA4H knockout mice and CD11c promoter-driven Cre recombinase-expressing BLT1 conditional knockout (BLT1 cKO) mice, we showed that the migration of BLT1hi DCs exacerbated allergic contact dermatitis. Comprehensive transcriptome analysis revealed that BLT1hi DCs preferentially induced Th1 differentiation by upregulating IL-12p35 expression, whereas BLT1lo DCs accelerated T cell proliferation by producing IL-2. Collectively, the data reveal an unexpected role for BLT1 as a novel DC subset marker and provide novel insights into the role of the LTB4-BLT1 axis in the spatiotemporal regulation of distinct DC subsets.

Innate and adaptive immunity regulate the inflammatory and erosive phenotypes observed in rheumatoid arthritis (RA) patients. Hence, identifying novel pathways that participate in different stages of RA pathology will provide valuable insights concerning the mechanistic behavior of different joint leukocytes and the strategy to restrain their activity. Recent findings have revealed that CCL21 poses as a risk factor for RA and expression of its receptor, CCR7, on circulating monocytes is representative of the patient’s disease activity score. Expression of CCR7 was found to be the hallmark of RA synovial fluid (SF) M1 macrophages (MΦs) and its levels were potentiated in response to M1 mediating factors and curtailed by M2 mediators in naïve MΦs. Intriguingly, although both CCR7 ligands, CCL19 and CCL21, are elevated in RA specimens, only CCL21 was predominately responsible for CCR7’s pathological manifestation of RA. Unique subset of MΦs differentiated in response to CCL21 stimulation, exhibited upregulation in Th17-polarizing monokines. Moreover, CCL21-activated monokines were capable of differentiating naïve T cells into joint Th17 cells, which also partook in RA osteoclastogenesis. Finally, to conserve chronic inflammation, SF CCL21 amplified RA neovascularization directly and indirectly by promoting RA FLS and MΦs to secrete proangiogenic factors, VEGF and IL-17. This review aims to shed light on the broad pathogenic impact of CCL21, linking immunostimulatory MΦs with Th17 cells, while concurrently advancing RA bone destruction and neovascularization.

Establishment of immune tolerance is crucial to protect humans against asthma. Promyelocytic leukemia zinc finger (PLZF) is an emerging suppressor of inflammatory responses. CCL21-CCR7 signaling mediates tolerance development. However, whether PLZF and CCL21-CCR7 are required for the development of asthma tolerance is unknown. Here, we found that Zbtb16 (coding PLZF) and Ccl21 were upregulated in OVA-induced asthma tolerance (OT) lungs by RNA-seq. PLZF physically interacted with GATA3 and its expression was higher in GATA3+ Th2 cells and ILC2s in OT lungs. Zbtb16-knockdown in lymphocytes promoted the differentiation of CD3e+ CD4+ T cells, particularly those producing IL-4 and IL-5. Moreover, iNKT cells with high expression of PLZF were recruited into the lungs via draining lymph nodes during tolerance. Blockade of CCL21-CCR7 signaling in OT mice decreased the PLZF+ cell population, abolished CCR7-induced PLZF+ iNKT recruitment to the lungs, enhanced Th2responses and exacerbated lung pathology. In OT mice, respiratory syncytial virus (RSV) infection impeded PLZF+ cell and CCR7+ PLZF+ iNKT cellrecruitment to the lungs and increased airway resistance. Collectively, these results indicate that PLZF could interact with GATA3 and restrain differentiation of IL-4- and IL-5-producing T cells, iNKT cells with high PLZF expression are recruited to the lungs via CCL21-CCR7 signaling to facilitate the development of asthma tolerance.

Multiple sclerosis (MS) is an immune-mediated and neurodegenerative disorder that results in inflammation and demyelination of the central nervous system (CNS). MS symptoms include walking difficulties, visual weakening, as well as learning and memory impairment, thus affecting the quality of the patient's life. Chemokines and chemokine receptors are expressed on the immune cells as well as the CNS resident cells. Several sets of chemokine receptors and their ligands tend to be pathogenic players in MS, including CCL2, CCL3, CCL4, CCL5, CCL7, CCL8, CCL11, CCL17, CCL19, CCL21, CCL22, CXCL1, CXCL8, CXCL9, CXCL10, CXCL11, and CXCL16. Furthermore, current modulatory drugs that are used in the treatment of MS and its animal model, the experimental autoimmune encephalomyelitis (EAE), affect the expression of several chemokine and chemokine receptors. In this review, we highlight the pathogenic roles of chemokines and their receptors as well as utilizing them as potential therapeutic targets through selective agents, such as specific antibodies and receptor blockers, or indirectly through MS or EAE immunomodulatory drugs.

Introduction: Chronic rhinosinusitis (CRS) is a local inflammation of the nasal mucosa and sinus that persists for >12 weeks. As CC chemokine ligand (CCL) 19 expression is known to be elevated in CRS, and CCL 19, CCL21, and CCL25 share the same atypical chemokine receptor 4, so we focused on CCL21 and CCL25. Objectives: To investigate the expression of CCL21 and CCL25 in different types of CRS and their significance in CRS development. Methods: A total of 116 patients participated in the study, and uncinate process mucosa or nasal polyp (NP) specimens were collected during surgery. Western blotting and immunohistochemistry were performed to detect the expression of CCL21 and CCL25, respectively, in the nasal mucosa. Immunofluorescence was used to determine their cellular localization in NPs, whereas macrophage culture was used to determine their relationships with macrophages. Results: Immunohistochemistry revealed that the expressions of CCL21 and CCL25 were increased in NPs only. Western blotting revealed that these expressions were gradually increased in control, CRS without NP and CRS with NP groups and were positively correlated with disease severity. Furthermore, increased expressions of CCL21 and CCL25 in NPs were not related to eosinophil infiltration. Immunofluorescence results demonstrated colocalization of CCL25+ cells and CD68+ macrophages. CCL25 expression was increased in macrophage culture, especially in M1 macrophages, while CCL21 expression was not significantly associated with macrophages. Conclusions: CCL21 and CCL25 were significantly upregulated in NPs and positively correlated with disease severity. CCL25 upregulation was related to M1 macrophages.

Chemokines are small proteins that promote leukocyte migration during development, infection, and inflammation. We and others isolated the unique chemokine CCL21, a potent chemo-attractant for naïve T-cells, naïve B-cells, and immature dendritic cells. CCL21 has a 37 amino acid carboxy terminal extension that is distinct from the rest of the chemokine family, which is thought to anchor it to venule endothelium where the amino terminus can interact with its cognate receptor, CCR7. We and others have reported that venule endothelium expressing CCL21 plays a crucial role in attracting naïve immune cells to sites of antigen presentation. In this study we generated a series of monoclonal antibodies to the amino terminus of CCL21 in an attempt to generate an antibody that blocked the interaction of CCL21 with its receptor CCR7. We found one humanized clone that blocked naïve T-cell migration towards CCL21, while memory effector T-cells were less affected. Using this monoclonal antibody, we also demonstrated that CCL21 is expressed in the mucosal venule endothelium of the large majority of inflammatory bowel diseases (IBD), including Crohn’s disease, ulcerative colitis, and also in celiac disease. This expression correlated with active IBD in 5 of 6 cases, whereas none of 6 normal bowel biopsies had CCL21 expression. This study raises the possibility that this monoclonal antibody could be used to diagnose initial or recurrent of IBD. Significantly, this antibody could also be used for therapeutic intervention in IBD by selectively interfering with recruitment of naïve immune effector cells to sites of antigen presentation, without harming overall memory immunity.

Chemotactic cytokines—chemokines—control immune cell migration in the process of initiation and resolution of inflammatory conditions as part of the body’s defense system. Many chemokines also participate in pathological processes leading up to and exacerbating the inflammatory state characterizing chronic inflammatory diseases. In this review, we discuss the role of dendritic cells (DCs) and the central chemokine receptor CCR7 in the initiation and sustainment of selected chronic inflammatory diseases: multiple sclerosis (MS), rheumatoid arthritis (RA), and psoriasis. We revisit the binary role that CCR7 plays in combatting and progressing cancer, and we discuss how CCR7 and DCs can be harnessed for the treatment of cancer. To provide the necessary background, we review the differential roles of the natural ligands of CCR7, CCL19, and CCL21 and how they direct the mobilization of activated DCs to lymphoid organs and control the formation of associated lymphoid tissues (ALTs). We provide an overview of DC subsets and, briefly, elaborate on the different T-cell effector types generated upon DC–T cell priming. In the conclusion, we promote CCR7 as a possible target of future drugs with an antagonistic effect to reduce inflammation in chronic inflammatory diseases and an agonistic effect for boosting the reactivation of the immune system against cancer in cell-based and/or immune checkpoint inhibitor (ICI)-based anti-cancer therapy.

Regulation of dendritic cell functions is a complex process in which several mediators play diverse roles as a network in a context-dependent manner. The precise mechanisms underlying dendritic cell functions have remained to be addressed. Semaphorins play crucial roles in regulation of various cell functions. We previously revealed that Semaphorin 3E (Sema3E) contributes to regulation of allergen-induced airway pathology partly mediated by controlling recruitment of conventional dendritic cell subsets in vivo, though the underlying mechanism remained elusive. In this study, we investigate the potential regulatory role of Sema3E in dendritic cells. We demonstrated that bone marrow-derived dendritic cells differentiated from Sema3e-/- progenitors have an enhanced migration capacity both at the baseline and in response to CCL21. The enhanced migration ability of Sema3E dendritic cells was associated with an overexpression of the chemokine receptor (CCR7), elevated Rac1 GTPase activity and F-actin polymerization. Using a mouse model of allergic airway sensitization, we observed that genetic deletion of Sema3E leads to a time dependent upregulation of CCR7 on CD11b+ conventional dendritic cells in the lungs and mediastinal lymph nodes. Furthermore, aeroallergen sensitization of Sema3e-/- mice lead to an enhanced expression of PD-L2 and IRF-4 as well as enhanced allergen uptake in pulmonary CD11b+ DC, compared to wild type littermates. Collectively, these data suggest that Sema3E implicates in regulation of dendritic cell functions which could be considered a basis for novel immunotherapeutic strategies for the diseases associated with defective dendritic cells in the future.

Purpose: To explore whether CCR7–CCL19 and CCR7-CCL21 affect the pathophysiology of the dry eye disease (DED) immuno-inflammatory response using a murine model.Methods: The mRNA expression levels o...

The immune system plays an important role in pregnancy. Chemokines recruit leukocytes at the maternal-fetal interface during early pregnancy. However, the role of the chemokine, C-C motif chemokine ligand 21 (CCL21), is less known. The aim of this study was to identify the expression of CCL21 and its receptor, CCR7, in the endometrium during estrous cycle and early pregnancy, and to investigate the functional effects of CCL21 on porcine trophectoderm (pTr) and porcine uterine luminal epithelial (pLE) cells. Our results indicated that CCL21 and CCR7 are increased in the glandular (GE) and luminal epithelium (LE) of the endometrium during early pregnancy, compared to estrous pigs. Recombinant CCL21 improved pTr and pLE cell proliferation through activation of the PI3K and MAPK pathways and suppression of tunicamycin-induced endoplasmic reticulum (ER) stress or LPS-induced inflammation. Collectively, these results provide novel insights into CCL21-mediated signaling mechanisms at the maternal-fetal interface during early pregnancy.

The expression of some chemokines and chemokine receptors is induced during the development of post-traumatic osteoarthritis (PTOA), but their involvement in the pathogenesis of the disease is unclear. The goal of this study was to test whether CCL21 and CXCL13 play a role in PTOA development. For this purpose, we evaluated the expression profiles of the chemokines Ccl21 and Cxcl13, matrix metalloproteinase enzymes Mmp3 and Mmp13, and inflammatory cell markers in response to partial medial meniscectomy and destabilization (MMD). We then assessed the effect of local administration of CCL21 neutralizing antibody on PTOA development and post-knee injury inflammation. The mRNA expression of both Ccl21 and Cxcl13 was induced early post-surgery, but only Ccl21 mRNA levels remained elevated 4 weeks post-surgery in rat MMD-operated knees compared to controls. This suggests that while both CXCL13 and CCL21 are involved in post-surgery inflammation, CCL21 is necessary for development of PTOA. A significant increase in the mRNA levels of Cd4, Cd8 and Cd20 was observed during the first 3 days post-surgery. Significantly, treatment with CCL21 antibody reduced post-surgical inflammation that was accompanied by a reduction in the expression of Mmp3 and Mmp13 and post-MMD cartilage degradation. Our findings are consistent with a role for CCL21 in mediating changes in early inflammation and subsequent cartilage degeneration in response to knee injury. Our results suggest that targeting CCL21 signaling pathways may yield new therapeutic approaches effective in delaying or preventing PTOA development following injury.

Migration of leukocytes from the skin to lymph nodes (LNs) via afferent lymphatic vessels (LVs) is pivotal for adaptive immune responses1,2. Circadian rhythms have emerged as important regulators of leukocyte trafficking to LNs via the blood3,4. Here, we demonstrate that dendritic cells (DCs) have a circadian migration pattern into LVs, which peaks during the rest phase in mice. This migration pattern is determined by rhythmic gradients in the expression of the chemokine CCL21 and of adhesion molecules in both mice and humans. Chronopharmacological targeting of the involved factors abrogates circadian migration of DCs. We identify cell-intrinsic circadian oscillations in skin lymphatic endothelial cells (LECs) and DCs that cogovern these rhythms, as their genetic disruption in either cell type ablates circadian trafficking. These observations indicate that circadian clocks control the infiltration of DCs into skin lymphatics, a process that is essential for many adaptive immune responses and relevant for vaccination and immunotherapies., Scheiermann and colleagues show that circadian clocks control the infiltration of dendritic cells into skin lymphatics in mice and humans, with a peak migration to the lymph nodes during the rest phase.

Gradients of chemokines and growth factors guide migrating cells and morphogenetic processes. Migration of antigen-presenting dendritic cells from the interstitium into the lymphatic system is dependent on chemokine CCL21, which is secreted by endothelial cells of the lymphatic capillary, binds heparan sulfates and forms gradients decaying into the interstitium. Despite the importance of CCL21 gradients, and chemokine gradients in general, the mechanisms of gradient formation are unclear. Studies on fibroblast growth factors have shown that limited diffusion is crucial for gradient formation. Here, we used the mouse dermis as a model tissue to address the necessity of CCL21 anchoring to lymphatic capillary heparan sulfates in the formation of interstitial CCL21 gradients. Surprisingly, the absence of lymphatic endothelial heparan sulfates resulted only in a modest decrease of CCL21 levels at the lymphatic capillaries and did neither affect interstitial CCL21 gradient shape nor dendritic cell migration toward lymphatic capillaries. Thus, heparan sulfates at the level of the lymphatic endothelium are dispensable for the formation of a functional CCL21 gradient.

Objectives The Cat Eye Syndrome Critical Region, Candidate 1 (CECR1) gene encoding adenosine deaminase 2 (ADA2) is mainly expressed by macrophages. Given the immunomodulatory functions of butyrate, we examined the effect of butyrate on CECR1 expression of macrophages and the relationship between ADA2 and M1/M2 macrophages-associated chemokines in pleural fluid of patients with tuberculous pleural effusion (TPE). Methods Expression of CECR1 was evaluated in lipopolysaccharide (LPS)-stimulated and/or butyrate treated THP-1 cells. The role of CECR1 on butyrate-induced immune response was evaluated using siRNA transfected THP-1 cells. M1/M2 chemokines and ADA2 were measured in pleural fluid of patients with TPE. Results Butyrate promoted the expression of CECR1 and M2-macrophage markers in THP-1 cells. CECR1 was found to be involved in regulating M2 polarization in THP-1 cells treated with LPS and butyrate. Among chemokines measured in pleural fluid of patients with TPE, there was a significant negative correlation between CCL21 and ADA2 levels and between CCL25 and ADA2 levels, and a significant positive correlation between TGF-β and ADA2 levels and between IL-22 and ADA2 levels. Conclusions CECR1 played an important role in the butyrate-modulated inflammatory responses in LPS-stimulated THP-1 cells. ADA2 may exert anti-inflammatory effects during the process of pleural inflammation in patients with TPE.

Background: Breast cancer (BC) is the most common malignancy among females worldwide. The tumor microenvironment usually prevents effective lymphocyte activation and infiltration, and suppresses infiltrating effector cells, leading to a failure of the host to reject the tumor. CC chemokines play a significant role in inflammation and infection. Methods: In our study, we analyzed the expression and survival data of CC chemokines in patients with BC using several bioinformatics analyses tools. Results: The mRNA expression of CCL2/3/4/5/7/8/11/17/19/20/22 was remarkably increased while CCL14/21/23/28 was significantly down-regulated in BC tissues compared with normal tissues. Methylation could down-regulate expression of CCL2/5/15/17/19/20/22/23/24/25/26/27 in BC. Low expression of CCL3/4/23 was found to be associated with drug resistance in BC. Results from Kaplan–Meier plotter and BC Gene-Expression Miner v4.2 (bcGenExMiner) v4.2 demonstrated that BC patients with high CCL8 and low CCL19/21/22 expression were more likely to have a worse prognosis. CCL8 expression was significantly up-regulated in BC tissues compared with normal tissues. High CCL8 expression was significantly correlated with negative PR, negative ER, positive nodal status, triple-negative BC subtype, basal-like BC subtype, triple-negative and basal-like BC subtype and high grades. CCL21 was down-regulated in BC, while high levels of CCL21 was associated with negative PR, triple-negative subtype, basal-like subtype and low tumor grade. Functional analysis demonstrated that CCL8 and CCL21 were involved in carcinogenesis, tumor immune escape and chemoresistance in BC. Conclusion: Integrative bioinformatics analysis demonstrated CCL8/21 as potential prognostic biomarkers in BC microenvironment.

Background: Immune checkpoint blockade that downregulates T cell evasion for effective immunity has provided a renewed interest in therapeutic cancer vaccines. Methods: Utilizing murine lung cancer models, we determined: tumor burden, TIL cytolysis, immunohistochemistry, flow cytometry, RNA Sequencing, CD4 T cells, CD8 T cells, CXCL9 chemokine, and CXCL10 chemokine neutralization to evaluate the efficacy of Programmed cell death protein 1 (PD-1) blockade combined with chemokine (C-C motif) ligand 21-dendritic cell tumor antigen (CCL21-DC tumor Ag) vaccine. Results: Anti-PD1 combined with CCL21-DC tumor Ag vaccine eradicated 75% of 12-day established tumors (150 mm3) that was enhanced to 90% by administering CCL21-DC tumor Ag vaccine prior to combined therapy. The effect of combined therapy was blocked by CD4, CD8, CXCL9, and CXCL10 neutralizing antibodies. Conclusion: PD-1 blockade therapy plus CCL21-DC tumor Ag vaccine could be beneficial to lung cancer patients.

Reflecting their importance in immunity, the activity of chemokines is regulated on several levels, including tissue and context-specific expression and availability of their cognate receptor on target cells. Chemokine synergism, affecting both chemokine and chemokine receptor function, has emerged as an additional control mechanism. We previously demonstrated that CXCL14 is a positive allosteric modulator of CXCR4 in its ability to synergize with CXCL12 in diverse cellular responses. Here, we have extended our study to additional homeostatic, as well as a selection of inflammatory chemokine systems. We report that CXCL14 strongly synergizes with low (sub-active) concentrations of CXCL13 and CCL19/CCL21 in in vitro chemotaxis with immune cells expressing the corresponding receptors CXCR5 and CCR7, respectively. CXCL14 by itself was inactive, not only on cells expressing CXCR5 or CCR7 but also on cells expressing any other known conventional or atypical chemokine receptor, as assessed by chemotaxis and/or β-arrestin recruitment assays. Furthermore, synergistic migration responses between CXCL14 and inflammatory chemokines CXCL10/CXCL11 and CCL5, targeting CXCR3 and CCR5, respectively, were marginal and occasional synergistic Ca2+ flux responses were observed. CXCL14 bound to 300-19 cells and interfered with CCL19 binding to CCR7-expressing cells, suggesting that these cellular interactions contributed to the reported CXCL14-mediated synergistic activities. We propose a model whereby tissue-expressed CXCL14 contributes to cell localization under steady-state conditions at sites with prominent expression of homeostatic chemokines. ispartof: FRONTIERS IN IMMUNOLOGY vol:11 ispartof: location:Switzerland status: published

Background: Targeting inhibitory immune checkpoint molecules has highlighted the need to find approaches enabling the activation of immune responses against cancer. Therapeutic vaccination, which induces specific immune responses against tumor antigens (Ags), is an attractive option. Methods: Utilizing a K-RasG12Dp53null murine lung cancer model we determined tumor burden, tumor-infiltrating T cell (TIL) cytolysis, immunohistochemistry, flow cytometry, and CD4 and CD8 depletion to evaluate the efficacy of PD-1 blockade combined with CCL21-DC tumor lysate vaccine. Results: Anti-PD-1 plus CCL21-DC tumor lysate vaccine administered to mice bearing established tumors (150 mm3) increased expression of perforin and granzyme B in the tumor microenvironment (TME), increased tumor-infiltrating T cell (TIL) activity, and caused 80% tumor eradication. Mice with treatment-induced tumor eradication developed immunological memory, enabling tumor rejection upon challenge and cancer-recurrence-free survival. The depletion of CD4 or CD8 abrogated the antitumor activity of combined therapy. PD-1 blockade or CCL21-DC tumor lysate vaccine monotherapy reduced tumor burden without tumor eradication. Conclusion: Immune checkpoint blockade promotes the activity of the therapeutic cancer vaccine. PD-1 blockade plus CCL21-DC tumor lysate vaccine therapy could benefit lung cancer patients.

Atypical chemokine receptors (ACKRs) have emerged as important regulators or scavengers of homeostatic and inflammatory chemokines. Among these atypical receptors, ACKR4 is reported to bind the homeostatic chemokines CCL19, CCL21, CCL25 and CXCL13. In a recent study by Matti et al., the authors show that ACKR4 is also a receptor for CCL20, previously established to bind to CCR6 only. They provide convincing evidence that, just as for its other chemokine ligands, ACKR4 rapidly internalizes CCL20 both in vitro and in vivo. Independently of this discovery, we undertook a screening program aiming at reassessing the activity of the 43 human chemokines toward ACKR4 using a highly sensitive β-arrestin recruitment assay. This systematic analysis confirmed CCL20 as a new agonist ligand for ACKR4 in addition to CCL19, CCL21, and CCL25. Furthermore, CCL22, which plays an important role in both homeostasis and inflammatory responses, and is known as a ligand for CCR4 and ACKR2 was found to also act as a potent partial agonist of ACKR4. In contrast, agonist activity of CXCL13 toward ACKR4 was disproved. This independent wide-range systematic study confirms the pairing of CCL20 with ACKR4 newly discovered by Matti and co-authors, and further refines the spectrum of chemokines activating ACKR4.

Chemokines are essential for guiding cell migration. Atypical chemokine receptors (ACKRs) contribute to the cell migration process by binding, internalizing and degrading local chemokines, which enables the formation of confined gradients. ACKRs are heptahelical membrane spanning molecules structurally related to G-protein coupled receptors (GPCRs), but seem to be unable to signal through G-proteins upon ligand binding. ACKR4 internalizes the chemokines CCL19, CCL21, and CCL25 and is best known for shaping functional CCL21 gradients. Ligand binding to ACKR4 has been shown to recruit β-arrestins that has led to the assumption that chemokine scavenging relies on β-arrestin-mediated ACKR4 trafficking, a common internalization route taken by class A GPCRs. Here, we show that CCL19, CCL21, and CCL25 readily recruited β-arrestin1 and β-arrestin2 to human ACKR4, but found no evidence for β-arrestin-dependent or independent ACKR4-mediated activation of the kinases Erk1/2, Akt, or Src. However, we demonstrate that β-arrestins interacted with ACKR4 in the steady-state and contributed to the spontaneous trafficking of the receptor in the absence of chemokines. Deleting the C-terminus of ACKR4 not only interfered with the interaction of β-arrestins, but also with the uptake of fluorescently labeled cognate chemokines. We identify the GPCR kinase GRK3, and to a lesser extent GRK2, but not GRK4, GRK5, and GRK6, to be recruited to chemokine-stimulated ACKR4. We show that GRK3 recruitment proceded the recruitment of β-arrestins upon ACKR4 engagement and that GRK2/3 inhibition partially interfered with steady-state interaction and chemokine-driven recruitment of β-arrestins to ACKR4. Overexpressing β-arrestin2 accelerated the uptake of fluorescently labeled CCL19, indicating that β-arrestins contribute to the chemokine scavenging activity of ACKR4. By contrast, cells lacking β-arrestins were still capable to take up fluorescently labeled CCL19 demonstrating that β-arrestins are dispensable for chemokine scavenging by ACKR4. published

Whyte et al. demonstrate that regulation of intratumor CCL21 and DC trafficking from tumors by the atypical chemokine receptor 4 curtails intratumor CD8+ T cell accumulation and immunotherapy efficacy., Current immunotherapies involving CD8+ T cell responses show remarkable promise, but their efficacy in many solid tumors is limited, in part due to the low frequency of tumor-specific T cells in the tumor microenvironment (TME). Here, we identified a role for host atypical chemokine receptor 4 (ACKR4) in controlling intratumor T cell accumulation and activation. In the absence of ACKR4, an increase in intratumor CD8+ T cells inhibited tumor growth, and nonhematopoietic ACKR4 expression was critical. We show that ACKR4 inhibited CD103+ dendritic cell retention in tumors through regulation of the intratumor abundance of CCL21. In addition, preclinical studies indicate that ACKR4 and CCL21 are potential therapeutic targets to enhance responsiveness to immune checkpoint blockade or T cell costimulation.

Dendritic cells (DCs) are well known to be essential immunocytes involved in innate and adaptive immunity. DCs are classified as conventional dendritic cells (cDCs) and plasmacytoid dendritic cells (pDCs). Recently, the accumulation of pDCs in inflamed tissues and lymphoid tissues has been considered to be a possible contributing factor in the development of immunological diseases, but little is known about the pathophysiological roles of pDCs in immunological diseases. To date, many studies have demonstrated that many kinds of Kampo formulas can regulate immunological reactions in human immune diseases. Thus, we screened Kampo formulas to identify an agent that inhibits pDC migration. Furthermore, we investigated the therapeutic effects of these formulas on a murine DNFB-induced allergic contact dermatitis model. Bone marrow-derived pDCs (BMpDCs) were derived from the bone marrow cells of BALB/c mice in a culture medium with Flt3 ligand. The effects of Kampo formulas on BMpDC migration were evaluated by assessing the number, velocity, and directionality of BMpDCs chemotaxing toward the more concentrated side of a chemokine (C-C motif) ligand 21 (CCL21) gradient. The Kampo formulas that exerted inhibitory effects on pDC migration were orally administered to DNFB-induced allergic contact dermatitis model mice. Byakkokaninjinto reduced the number of migrated BMpDCs and suppressed the velocity and directionality of BMpDC migration in a chemotaxis assay. Gypsum Fibrosum and Ginseng Radix, which are components of byakkokaninjinto, obviously suppressed the velocity of BMpDC migration. Furthermore, Gypsum Fibrosum significantly suppressed the directionality of BMpDC migration. In DNFB-induced allergic contact dermatitis model mice, byakkokaninjinto markedly abrogated ear swelling in late-phase allergic reactions. In conclusions, byakkokaninjinto, which has an inhibitory effect on pDC migration, was able to prevent the occurrence of allergic contact dermatitis, suggesting that pDCs were involved in the onset of allergic contact dermatitis in the mouse model. Therefore, byakkokaninjinto is anticipated to be a therapeutic agent for disorders related to pDC migration.

This study mainly investigated the effects of matrine on cell apoptosis and the effects of anticancer drugs in non-small cell lung cancer (NSCLC) cell lines (A549 and LK2 cells). The results showed that matrine (≥10 μM) caused a significant inhibition on cell viability and 10 and 100 μM matrine induced cell apoptosis via influencing p53, bax, casp3, and bcl-2 expressions in A549 cells. In addition, matrine significantly down-regulated C-C chemokine receptor type 7 (CCR7) expression, and blocking the down-regulation of CCR7 by exogenous chemokine ligand 21 (CCL21) treatment alleviated matrine-caused effects of apoptosis genes in A549 cells. The results were further validated in LK2 cells that matrine regulated apoptosis gene expressions, which were reversed by CCL21 treatment. Furthermore, matrine enhances the effects of cisplatin, 5-fluorouracil, and paclitaxel in A549 cells, and the anticancer effects exhibit a dosage-dependent manner. In summary, matrine induced cell apoptosis and enhanced the effects of anticancer drugs in NSCLC cells; the mechanism might be associated with the CCR7 signal.

Cigarette smoking aggravates the symptoms of asthma, leading to the rapid decline of lung function. Dendritic cells (DCs) and lymphocytes are considered initiating and promoting factors for the airway inflammation reactions of asthma. In addition, activation of CC chemokine receptor 7 (CCR7) by chemokine (C-C motif) ligand (CCL) 19 and 21 promotes DCs and T cells migration to lymphoid tissues during inflammation. We aimed to examine how cigarette smoke affects the expression of CCR7 in the lungs of asthmatic rats and explore the signaling mechanism linking CCR7 expression to exacerbation of symptoms.Forty Wistar rats were randomized to four groups: control, asthma, smoke exposure, and asthma with smoke exposure groups. A rat asthma model was established by intraperitoneal ovalbumin injection. CCR7 expression was examined with immunohistochemistry and western blotting. The number of airway DCs was determined by OX62 immunohistochemistry. Interferon (INF)-γ, interleukin (IL)-4, CCL19, and CCL21 expression levels in blood and bronchioalveolar lavage fluid (BALF) were determined by enzyme-linked immunosorbent assays (ELISAs).Tissue CCR7 expression, peripheral blood and BALF CCL19 and CCL21 concentrations, and the number of airway DCs were significantly higher in the asthma with smoke exposure group than the asthma group (P0.01). In addition, INF-γ expression was decreased and IL-4 increased in the asthma and asthma with smoke exposure groups compared with the control group (P0.01), and in the asthma with smoke exposure group compared with the asthma group (P0.01). Expression of CCR7 correlated negatively with INF-γ expression in peripheral blood and BALF (P0.01), and positively with the airway DCs and IL-4 expression in the peripheral blood and BALF (P0.01).Cigarette smoking may aggravate asthma symptoms by attenuating immunity, possibly through CCR7-mediated DCs aggregation in lung tissue.

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

Autism spectrum disorders (ASD) are characterized by disturbances in social interactions and communication, restricted repetitive interests, and stereotyped behavior. Cumulative evidence recommends that there are immune alterations in ASD. Chemokine receptors are known to play an important role in the central nervous system (CNS) and in many neuro inflammatory disorders. The main objective of this study was to explore the role of CXC and CC chemokine receptors signaling in children with autism. We examined chemokine receptor production of CXCR2, CXCR3, CXCR5, and CXCR7 in all peripheral blood mononuclear cells (PBMCs) and in CD4+ T cells of typically developing control children (TD) and autistic children (AU). We also examined chemokine receptor production of CCR3, CCR5, CCR7, and CCR9 in all PBMCs and in CD4+ T cells of AU and TD samples using flow cytometric analysis. In addition, we measured mRNA expression levels of CXC and CC chemokine receptors using quantitative RT-PCR analysis. Our results showed the increased production of CXCR2+, CXCR3+, CXCR5+, and CXCR7+ and CCR3+, CCR5+, CCR7+, and CCR9+ in all PBMCs and in CD4+ T cells of children with AU as compared to TD controls. Our results show that chemokine receptor signaling components might provide unique therapeutic targets for children with AU and other neurological disorders.

Kara et al. show that ACKR4 regulates early activated B cell differentiation fate. ACKR4 limits the early proliferation of activated B cells by restricting their initial access to the splenic interfollicular zone., Activated B cells can initially differentiate into three functionally distinct fates—early plasmablasts (PBs), germinal center (GC) B cells, or early memory B cells—by mechanisms that remain poorly understood. Here, we identify atypical chemokine receptor 4 (ACKR4), a decoy receptor that binds and degrades CCR7 ligands CCL19/CCL21, as a regulator of early activated B cell differentiation. By restricting initial access to splenic interfollicular zones (IFZs), ACKR4 limits the early proliferation of activated B cells, reducing the numbers available for subsequent differentiation. Consequently, ACKR4 deficiency enhanced early PB and GC B cell responses in a CCL19/CCL21-dependent and B cell–intrinsic manner. Conversely, aberrant localization of ACKR4-deficient activated B cells to the IFZ was associated with their preferential commitment to the early PB linage. Our results reveal a regulatory mechanism of B cell trafficking via an atypical chemokine receptor that shapes activated B cell fate.

Objective The chemokine receptor CXCR4 is highly expressed in tumor cells and plays an important role in tumor metastasis. In the present study, we report on the evaluation of a new radiopharmaceutical peptide for its potential to visualization for CXCR4-expressing tumors in vivo. Methods A CXCR4 antagonist analogue was synthesized using a standard Fmoc solid phase strategy and labeled with 99mTc via HYNIC and EDDA/tricine as coligands. In addition, stability in human serum, receptor binding internalization, in vivo tumor uptake, and tissue biodistribution were evaluated. Labeling procedure has been accomplished at 100 °C. RTLC and HPLC analysis methods have been used to confirm the procedure. The receptor binding internalization rate studied using B16-F10 melanoma tumor cells. C57BL/6 mice bearing B16-F10 tumor were used for radiopeptide biodistribution studies. Results Labeling yield of > 95% (n = 3) was obtained corresponding to a specific activity of 123 ± 60 GBq/μmol. Efficient stability in the presence of human serum was observed. The radioligand showed specific internalization (of total add) into B16-F10 cells (1.57 ± 0.27% at 2 h). In animal biodistribution study, the uptake in mouse tumor was 2.74 ± 0.47% ID/g after 15 min (percentage of injected dose per gram of tissue). Conclusion Results of this study show that labeled peptide conjugate could be a potential candidate for diagnosis of malignant tumors.

T-cell infiltration into tumors represents a critical bottleneck for immune-mediated control of cancer. We previously showed that this bottleneck can be overcome by depleting immunosuppressive Foxp3+ regulatory T cells (Tregs), a process that can increase frequencies of tumor-infiltrating lymphocytes through promoting the development of specialized portals for lymphocyte entry, namely high endothelial venules (HEVs). In this paper, we used a carcinogen-induced tumor model that allows for coevolution of the tumor microenvironment and the immune response to demonstrate that Treg depletion not only results in widespread disruption to HEV networks in lymph nodes (LNs) but also activates CD8+ T cells, which then drive intratumoral HEV development. Formation of these vessels contrasts with ontogenic HEV development in LNs in that the process is dependent on the TNF receptor and independent of lymphotoxin β receptor–mediated signaling. These intratumoral HEVs do not express the chemokine CCL21, revealing a previously undescribed intratumoral blood vessel phenotype. We propose a model where Treg depletion enables a self-amplifying loop of T-cell activation, which promotes HEV development, T-cell infiltration, and ultimately, tumor destruction. The findings point to a need to test for HEV development as part of ongoing clinical studies in patients with cancer. Cancer Immunol Res; 5(11); 1005–15. ©2017 AACR.

The chemokine receptor CCR7 drives leukocyte migration into and within lymph nodes (LNs). It is activated by chemokines CCL19 and CCL21, which are scavenged by the atypical chemokine receptor ACKR4. CCR7-dependent navigation is determined by the distribution of extracellular CCL19 and CCL21, which form concentration gradients at specific microanatomical locations. The mechanisms underpinning the establishment and regulation of these gradients are poorly understood. In this article, we have incorporated multiple biochemical processes describing the CCL19–CCL21–CCR7–ACKR4 network into our model of LN fluid flow to establish a computational model to investigate intranodal chemokine gradients. Importantly, the model recapitulates CCL21 gradients observed experimentally in B cell follicles and interfollicular regions, building confidence in its ability to accurately predict intranodal chemokine distribution. Parameter variation analysis indicates that the directionality of these gradients is robust, but their magnitude is sensitive to these key parameters: chemokine production, diffusivity, matrix binding site availability, and CCR7 abundance. The model indicates that lymph flow shapes intranodal CCL21 gradients, and that CCL19 is functionally important at the boundary between B cell follicles and the T cell area. It also predicts that ACKR4 in LNs prevents CCL19/CCL21 accumulation in efferent lymph, but does not control intranodal gradients. Instead, it attributes the disrupted interfollicular CCL21 gradients observed in Ackr4-deficient LNs to ACKR4 loss upstream. Our novel approach has therefore generated new testable hypotheses and alternative interpretations of experimental data. Moreover, it acts as a framework to investigate gradients at other locations, including those that cannot be visualized experimentally or involve other chemokines.

Cytokine-like protein 1 (CYTL1) is a small widely expressed secreted protein lacking significant primary sequence homology to any other known protein. CYTL1 expression appears to be highest in the hematopoietic system and in chondrocytes; however, maintenance of cartilage in mouse models of arthritis is its only reported function in vivo. Despite lacking sequence homology to chemokines, CYTL1 is predicted by computational methods to fold like a chemokine, and has been reported to function as a chemotactic agonist at the chemokine receptor CCR2 in mouse monocyte/macrophages. Nevertheless, since chemokines are defined by structure and chemokine receptors are able to bind many non-chemokine ligands, direct determination of the CYTL1 tertiary structure will ultimately be required to know whether it actually folds as a chemokine and therefore is a chemokine. Towards this goal, we have developed a method for producing functional recombinant human CYTL1 in bacteria, and we provide new evidence about the biophysical and biochemical properties of recombinant CYTL1. Circular dichroism analysis showed that, like chemokines, CYTL1 has a higher content of beta-sheet than alpha-helix secondary structure. Furthermore, recombinant CYTL1 promoted calcium flux in chondrocytes. Nevertheless, unlike chemokines, CYTL1 had limited affinity to proteoglycans. Together, these properties further support cytokine-like properties for CYTL1 with some overlap with the chemokines.

Transendothelial migration (TEM) of Th1 and Th17 cells across the blood-brain barrier (BBB) has a critical role in the development of experimental autoimmune encephalomyelitis (EAE). How cytokines produced by inflammatory Th1 and Th17 cells damage the endothelial BBB and promote transendothelial migration of immune cells into the central nervous system (CNS) during autoimmunity is not understood. We therefore investigated the effect of various cytokines on brain endothelial cells. Among the various cytokines tested, such as Th1 (IFN-γ, IL-1α, IL-1β, TNF-α, IL-12), Th2 (IL-3, IL-4, IL-6 and IL-13), Th17 (IL-17A, IL-17F, IL-21, IL-22, IL-23, GM-CSF) and Treg-specific cytokines (IL-10 and TGF-β), IFN-γ predominantly showed increased expression of ICAM-1, VCAM-1, MAdCAM-1, H2-Kb and I-Ab molecules on brain endothelial cells. Furthermore, IFN-γ induced transendothelial migration of CD4+ T cells from the apical (luminal side) to the basal side (abluminal side) of the endothelial monolayer to chemokine CCL21 in a STAT-1-dependent manner. IFN-γ also favored the transcellular route of TEM of CD4+ T cells. Multicolor immunofluorescence and confocal microscopic analysis showed that IFN-γ induced relocalization of ICAM-1, PECAM-1, ZO-1 and VE-cadherin in the endothelial cells, which affected the migration of CD4+ T cells. These findings reveal that the IFN-γ produced during inflammation could contribute towards disrupting the BBB and promoting TEM of CD4+ T cells. Our findings also indicate that strategies that interfere with the activation of CNS endothelial cells may help in controlling neuroinflammation and autoimmunity.

We previously demonstrated that mesenchymal stem cells (MSCs) ameliorated experimental autoimmune uveoretinitis (EAU) in rats. Recently, MSC-derived exosomes (MSC-Exo) were thought to carry functions of MSCs. In this study, we tested the effect of local administration of human MSC-Exo on established EAU in the same species. Rats with EAU induced by immunization with interphotoreceptor retinol-binding protein 1177–1191 peptide were treated by periocular injections of increasing doses of MSC-Exo starting at the disease onset for 7 consecutive days. The in vitro effects of MSC-Exo on immune cell migration and responder T cell proliferation were examined by chemotactic assays and lymphocyte proliferation assays, respectively. We found that MSC-Exo greatly reduced the intensity of ongoing EAU as their parent cells by reducing the infiltration of T cell subsets, and other inflammatory cells, in the eyes. Furthermore, the chemoattractive effects of CCL2 and CCL21 on inflammatory cells were inhibited by MSC-Exo. However, no inhibitory effect of MSC-Exo on IRBP-specific T cell proliferation was observed. These results suggest that MSC-Exo effectively ameliorate EAU by inhibiting the migration of inflammatory cells, indicating a potential novel therapy of MSC-Exo for uveitis.

Chemokine (C-C) motif ligand 21 (CCL21) is involved in immunosurveillance and has recently garnered the attention of neuro-oncologists and neuroscientists. CCL21 contains an extended C-terminus, which increases binding to lymphatic glycosaminoglycans and provides a mechanism for cell trafficking by forming a stationary chemokine concentration gradient that allows cell migration via haptotaxis. CCL21 is expressed by endothelial cells of the blood-brain barrier in physiologic and pathologic conditions. CCL21 has also been implicated in leukocyte extravasation into the central nervous system. In this review, we summarize the role of CCL21 in immunosurveillance and explore its potential as an immunotherapeutic agent for the treatment of gliomas.

Background Epidermolysis bullosa (EB) is a congenital, refractory skin disease and there are no fundamental treatments. Recently, allogenic cell therapies are beginning to be applied as potential treatments, that are based on the concept that the allogenic cells can migrate into the skin and reconstitute the skin components. Although the mechanisms of cell migration into skin are not fully understood, chemokines are regarded as key factors in recruiting bone marrow-derived cells. Objectives Our study aims to elucidate the expression of chemokines in the EB patients. Methods We determined the expression of wound-healing related chemokines in the sera, keratinocytes, and skin tissues of EB patients and compared them to those of healthy volunteers by enzyme-linked immunosorbent assays, quantitative reverse transcription PCR, and immunofluorescence staining. Results The serum levels of CXCL12 and HMGB1 were found to be significantly elevated in the EB patients. Conversely, the serum levels of CCL21 were found to be lower in the EB patients than in healthy controls. In addition, the serum levels of CXCL12 tended to increase and the serum levels of CCL27 tended to decrease with an increase in the affected body surface areas. To detect the origin of the circulating chemokines, we performed immunofluorescence staining. CCL21, CCL27, HMGB1 and CXCL12 were stained more broadly in the EB patient tissues than those in the control tissues. Conclusions These results suggest that fluctuations in chemokine levels may contribute in a coordinated way to the wound-healing process and lend clues toward efficient cell therapies for EB.

Mammalian cells produce inflammatory cytokines and chemokines in response to innate immune signals and their expression is tightly regulated. Chemokine (C-X-C motif) ligand 2 (CXCL2), also known as macrophage inflammatory protein 2-alpha (MIP2-alpha), is an inflammatory chemokine belonging to the CXC chemokine family. CXCL2 is chemotactic for neutrophils and elevated expression of CXCL2 is associated with many inflammatory and autoimmune diseases. The Fli-1 gene belongs to the large Ets transcription factor family, whose members regulate a wide variety of cellular functions including the immune response. In this study, we demonstrate that endothelial cells transfected with Fli-1 specific siRNA produce significantly less CXCL2 compared to cells transfected with control siRNA after stimulation by the Toll-like receptor (TLR) 4 ligands, lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF-α). The production of CXCL2 in endothelial cells stimulated with LPS stimulation is dose-dependent. We found that Fli-1 binds to the CXCL2 promoter as established by Chromatin immunoprecipitation‎ (ChIP) assay. Transient transfection assays show that Fli-1 drives transcription from the CXCL2 promoter in a dose-dependent manner and Fli-1 regulates the expression of CXCL2 largely by directly binding to the promoter. Targeted knockdown and transient transfection experiments suggest that both Fli-1 and the p65 subunit of NF-κB affect the activation of CXCL2 in an additive manner. These results indicate that Fli-1 is a novel, critical transcription factor that regulates the expression of the inflammatory chemokine CXCL2.

CCL21Ser is one of the ligands for chemokine receptor CCR7. Kozai et al. report that CCL21Ser is essential for the accumulation of developing thymocytes in the thymic medulla and the establishment of self-tolerance in T cells, indicating a functional inequality among CCR7 ligands in vivo., The chemokine receptor CCR7 directs T cell relocation into and within lymphoid organs, including the migration of developing thymocytes into the thymic medulla. However, how three functional CCR7 ligands in mouse, CCL19, CCL21Ser, and CCL21Leu, divide their roles in immune organs is unclear. By producing mice specifically deficient in CCL21Ser, we show that CCL21Ser is essential for the accumulation of positively selected thymocytes in the thymic medulla. CCL21Ser-deficient mice were impaired in the medullary deletion of self-reactive thymocytes and developed autoimmune dacryoadenitis. T cell accumulation in the lymph nodes was also defective. These results indicate a nonredundant role of CCL21Ser in the establishment of self-tolerance in T cells in the thymic medulla, and reveal a functional inequality among CCR7 ligands in vivo.

In allergic airway inflammation, VEGFR-3-mediated lymphangiogenesis occurs in humans and mouse models, yet its immunological roles, particularly in adaptive immunity, are poorly understood. Here, we explored how pro-lymphangiogenic signaling affects the allergic response to house dust mite (HDM). In the acute inflammatory phase, the lungs of mice treated with blocking antibodies against VEGFR-3 (mF4-31C1) displayed less inflammation overall, with dramatically reduced innate and T cell numbers and reduced inflammatory chemokine levels. However, when inflammation was allowed to resolve and memory recall was induced 2 months later, mice treated with mF4-31C1 as well as VEGF-C/-D knockout models showed exacerbated type 2 memory response to HDM, with increased Th2 cells, eosinophils, type 2 chemokines, and pathological inflammation scores. This was associated with lower CCL21 and decreased TRegs in the lymph nodes. Together, our data imply that VEGFR-3 activation in allergic airways both help initiate the acute inflammatory response as well as regulate the adaptive (memory) response, possibly in part by shifting the TReg/Th2 balance. This introduces new immunomodulatory roles for pro-lymphangiogenic VEGFR-3 signaling in allergic airway inflammation and suggests that airway lymphatics may be a novel target for treating allergic responses.

The spleen is an important secondary lymph organ. Splenomegaly induced by anemia could affect the function of spleen in immune responses. We observe that anemia induced in mice with reduced peripheral T cell trafficking to the spleen T cell zones as well as CCL21 and CCL19 expression. In accordance with previous research, we found that the production of EPO in the mice kidney was sharply increased post anemia. In addition, mice were injected with different doses of EPO. Our results show that with the increased dosage of EPO, the chemokine expression in the spleen is lowered with a decrease in peripheral T cell homing to the spleen T cell zones. At last, our results show that the anemia mice model administrated with anti-EPO antibody had a higher expression of spleen CCL19 and CCL21 and an increased count of periphery T cells trafficking to spleen T cell zones at day 3 post induction. These data indicate that anemia could disturb T cell movement in the spleen, which might further affect T cell immune response, with partial involvement of EPO.

Dendritic cells (DCs) are the most effective professional antigen-presenting cell. They ferry antigen from the extremities to T cells and are essential for the initiation of an adaptive immune response. Despite interest in how DCs respond to chemical stimuli, there have been few attempts to model DC migration. In this paper, we simulate the motility of DCs by modeling the generation of forces by filopodia and a force balance on the cell. The direction of fliopodial extension is coupled to differential occupancy of cognate chemokine receptors across the cell. Our model simulates chemokinesis and chemotaxis in a variety of chemical and mechanical environments. Simulated DCs undergoing chemokinesis were measured to have a speed of 5.1 ± 0.07 μm·min-1 and a persistence time of 3.2 ± 0.46 min, consistent with experiment. Cells undergoing chemotaxis exhibited a stronger chemotactic response when exposed to lower average chemokine concentrations, also consistent with experiment. We predicted that when placed in two opposing gradients, cells will cluster in a line, which we call the “line of equistimulation;” this clustering has also been observed. We calculated the effect of varying gradient steepness on the line of equistimulation, with steeper gradients resulting in tighter clustering. Moreover, gradients are found to be most potent when cells are in a gradient of chemokine whose mean concentration is close to the binding of the Kd to the receptor, and least potent when the mean concentration is 0.1Kd. Comparing our simulations to experiment, we can give a quantitative measure of the strength of certain chemokines relative to others. Assigning the signal of CCL19 binding CCR7 a baseline strength of 1, we found CCL21 binding CCR7 had a strength of 0.28, and CXCL12 binding CXCR4 had a strength of 0.30. These differences emerge despite both chemokines having virtually the same Kd, suggesting a mechanism of signal amplification in DCs requiring further study., Author summary Dendritic cells harvest and display antigen to other immune cells, and motility is essential to their function. Dendritic cells use filopodia to pull themselves forward, and orient their filopodia based on signals received from chemokines. We developed a model of dendritic cell motion based on a force balance, in which pulling from filopodia (calculated from a well-established model of filopodial adhesion-clutch dynamics) is counterbalanced by adhesive friction, and where the angular orientation of filopodia is based on the strength of chemotactic signal. The model can explain directional motion in chemotactic gradients, as well as the effect of superposition of coincident gradients of chemokine on chemotaxis. The model also identifies conditions in which dendritic cells can be focused at a single location when confronted with countergradients of chemokine. The model makes specific prediction regarding dendritic cell motion and defines conditions for the design of extracorporeal devices for focusing the position of dendritic cells.

Objective: We examined the effect of β-adrenoceptor (AR) blockade in the preclinical phase of experimental autoimmune encephalomyelitis (EAE), the most commonly used model of multiple sclerosis, on the development of primary CD4+ T-cell responses in draining lymph nodes (dLNs). Methods: CD11b+ cell migration to dLNs, CD4+ T-cell activation/proliferation, and IL-17+ CD4+ (Th17) cell numbers in dLN and spinal cord (SC) were examined in male and female Dark Agouti rats using flow cytometry analysis. Results: Irrespective of sex, in propranolol-treated (PT) rats, migration of CD11b+ antigen-presenting cells from the site of immunization to dLNs was impaired compared with saline-treated controls and consequently the frequency of all CD11b+ cells in dLNs and activated cells among them, too. This correlated with decreased expression of CCL19/21 transcripts in dLNs. Consistently, the frequency of activated/proliferating cells among dLN CD4+ T cells was reduced in PT rats. Additionally, propranolol reduced the number of Th17 cells in dLNs and SC. Consistently, male and female PT rats exhibited a decreased incidence of EAE and prolonged duration of the asymptomatic disease phase. Conclusion: This study suggests that sympathetic dysregulation is involved in the outbreak of clinical EAE.

To contain autoimmunity, pathogenic T cells must be eliminated or diverted from reaching the target organ. Recently, we defined a novel form of T cell tolerance whereby treatment with Ag downregulates expression of the chemokine receptor CXCR3 and prevents diabetogenic Th1 cells from reaching the pancreas, leading to suppression of type 1 diabetes (T1D). This report defines the signaling events underlying Ag-induced chemokine receptor-mediated tolerance. Specifically, we show that the mammalian target of rapamycin complex 1 (mTORC1) is a major target for induction of CXCR3 downregulation and crippling of Th1 cells. Indeed, Ag administration induces upregulation of programmed death-ligand 1 on dendritic cells in a T cell–dependent manner. In return, programmed death-ligand 1 interacts with the constitutively expressed programmed death-1 on the target T cells and stimulates docking of Src homology 2 domain-containing tyrosine phosphatase 2 phosphatase to the cytoplasmic tail of programmed death-1. Active Src homology 2 domain-containing tyrosine phosphatase 2 impairs the signaling function of the PI3K/protein kinase B (AKT) pathway, leading to functional defect of mTORC1, downregulation of CXCR3 expression, and suppression of T1D. Thus, mTORC1 component of the metabolic pathway serves as a target for chemokine receptor-mediated T cell tolerance and suppression of T1D.

Biomarkers for pulmonary manifestations in systemic lupus erythematosus (SLE) are missing. Plasma samples of nine SLE patients with known pulmonary involvement (SLEpulm) and nine SLE patients without pulmonary involvement (SLE) were tested by multiplex microarray analysis for various cyto- and chemokines. Significantly decreased lung function paramters for forced vital capacity (FVC), total lung capacity (TLC), diffusion capacity for carbon monoxide (DLCO) and diffusion of CO corrected on lung volume (KLCO) were observed in SLEpulm as compared to SLE patients. CC chemokine ligand 21 (CCL21) and interferon gamma-induced protein 10 (IP-10) levels were significantly higher in SLEpulm, than in patients without pulmonary manifestations. CCL21 correlated negatively with DLCO ( r = −0.73; p CO ( r = −0.62; p CO/KLCO changes and were associated with significant increase in CCL21 and IP-10. These chemokines might serve as potential biomarkers of lung involvement in SLE patients.

The atypical chemokine receptor CXCR7/ACKR3 binds two endogenous chemokines, CXCL12 and CXCL11, and is upregulated in many cancers or following infection by several cancer-inducing viruses, including HHV-8. ACKR3 is a ligand-scavenging receptor and does not activate the canonical G protein pathways but was proposed to trigger β-arrestin-dependent signaling. Here, we identified the human herpesvirus 8-encoded CC chemokine vCCL2/vMIP-II as a third high-affinity ligand for ACKR3. vCCL2 acted as partial ACKR3 agonist, inducing β-arrestin recruitment to the receptor, subsequent reduction of its surface levels and its delivery to endosomes. In addition, ACKR3 reduced vCCL2-triggered MAP kinase and PI3K/Akt signaling through other chemokine receptors. Our data suggest that ACKR3 acts as a scavenger receptor for vCCL2, regulating its availability and activity toward human receptors, thereby likely controlling its function in HHV-8 infection. Our study provides new insights into the complex crosstalk between viral chemokines and host receptors as well as into the biology of ACKR3, this atypical and still enigmatic receptor.