Expression Of Homeostatic Chemokines Research Articles

CXCL14 Preferentially Synergizes With Homeostatic Chemokine Receptor Systems.

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.

Characterization of Dual and Homeostatic Chemokine Expression and Response to Bacterial Infection in Large Yellow Croaker, Larimichthys crocea

Characterization of Dual and Homeostatic Chemokine Expression and Response to Bacterial Infection in Large Yellow Croaker, Larimichthys crocea

134: Interleukin-27 as a novel antagonist of ectopic lymphoid-like structure development in early inflammatory arthritis

Evaluation of joint tissue from early inflammatory arthritis patients through ultrasound-guided synovial biopsy has enabled disease classification based on local pathology. For example, the disease can be classed as fibroblast-, myeloid- or lymphoid-driven. Lymphoid histopathology can be further divided into patients displaying either diffuse infiltrates, or ectopic lymphoid-like structures (ELS) reminiscent of the follicular compartments in secondary lymphoid organs. Approximately 25% of rheumatoid arthritis (RA) patients develop ELS and display severe symptoms associated with local immune cell priming and autoantibody production. However, cytokine control of ELS development in inflammatory arthritis is poorly defined. Interleukin (IL)-27 is a negative regulator of adaptive immune responses. To investigate the role of IL-27 in inflammatory arthritis, wild type (WT) and IL-27 receptor (IL-27R)-deficient mice were exposed to antigen-induced arthritis. IL-27R-deficient mice developed exacerbated inflammatory arthritis, displaying increased synovial infiltrate, hypertrophy and bone erosions. Heightened peripheral T H 17- and B-cell responses in IL-27R-deficiency were reflected in increased serum IL-17 levels and antigen-specific IgG titers. Strikingly, IL-27R-deficient mice developed synovial histopathology reminiscent of RA patients with ELS, comprising synovial lymphoid aggregates with distinct T-cell (CD3 + ), B-cell (B220 + ) and DC (F/480 + , CD21 + ) areas that were absent in WT mice. Development of lymphoid aggregates was associated with elevated synovial expression of homeostatic chemokines that promote ectopic lymphoneogenesis (e.g. Cxcl13, Ccl21 ) and the transcriptional regulator Bcl-6 , which is involved in germinal center organization and functional regulation. Ectopic lymphoneogenesis in IL-27R-deficient mice was not associated with an increase in synovial IL-6 or IL-21 expression. Studies in clinical RA patients reflect our experimental outcomes and reveal reduced synovial IL-27 expression in patients with joint histopathology comprising ELS compared to patients with diffuse lymphocytic infiltrates. Thus, IL-27 may negatively regulate the formation of ELS in human pathologies such as RA and represents a potential biomarker of synovial histopathology in early RA.

SP0114 Innate lymphoid cells and their interaction with stroma in tertiary lymphoid tissue formation

Ectopic or tertiary lymphoid tissues (TLTs) are frequently associated with sites of chronic inflammation and are thought to contribute to pathological responses. They typically contain various hematopoietic cell types including...

CXCL13 Production in B Cells via Toll-like Receptor/Lymphotoxin Receptor Signaling Is Involved in Lymphoid Neogenesis in Chronic Obstructive Pulmonary Disease

Little is known about what drives the appearance of lymphoid follicles (LFs), which may function as lymphoid organs in chronic obstructive pulmonary disease (COPD). In animal infection models, pulmonary LF formation requires expression of homeostatic chemokines by stromal cells and dendritic cells, partly via lymphotoxin. To study the role of homeostatic chemokines in LF formation in COPD and to identify mechanism(s) responsible for their production. Peripheral lung homeostatic chemokine and lymphotoxin expression were visualized by immunostainings and quantified by ELISA/quantitative reverse transcriptase-polymerase chain reaction in patients with COPD with and without LFs. Expression of lymphotoxin and homeostatic chemokine receptors was investigated by flow cytometry. Primary lung cell cultures, followed by ELISA/quantitative reverse transcriptase-polymerase chain reaction/flow cytometry, were performed to identify mechanisms of chemokine expression. Polycarbonate membrane filters were used to assess primary lung cell migration toward lung homogenates. LFs expressed the homeostatic chemokine CXCL13. Total CXCL13 levels correlated with LF density. Lung B cells of patients with COPD were important sources of CXCL13 and lymphotoxin and also expressed their receptors. Cigarette smoke extract, H2O2, and LPS exposure up-regulated B cell-derived CXCL13. The LPS-induced increase in CXCL13 was partly mediated via lymphotoxin. Notably, CXCL13 was required for efficient lung B-cell migration toward COPD lung homogenates and induced lung B cells to up-regulate lymphotoxin, which further promoted CXCL13 production, establishing a positive feedback loop. LF formation in COPD may be driven by lung B cells via a CXCL13-dependent mechanism that involves toll-like receptor and lymphotoxin receptor signaling.

Lymphotoxin-beta receptor blockade reduces CXCL13 in lacrimal glands and improves corneal integrity in the NOD model of Sjögren's syndrome

IntroductionIn Sjögren's syndrome, keratoconjunctivitis sicca (dry eye) is associated with infiltration of lacrimal glands by leukocytes and consequent losses of tear-fluid production and the integrity of the ocular surface. We investigated the effect of blockade of the lymphotoxin-beta receptor (LTBR) pathway on lacrimal-gland pathology in the NOD mouse model of Sjögren's syndrome.MethodsMale NOD mice were treated for up to ten weeks with an antagonist, LTBR-Ig, or control mouse antibody MOPC-21. Extra-orbital lacrimal glands were analyzed by immunohistochemistry for high endothelial venules (HEV), by Affymetrix gene-array analysis and real-time PCR for differential gene expression, and by ELISA for CXCL13 protein. Leukocytes from lacrimal glands were analyzed by flow-cytometry. Tear-fluid secretion-rates were measured and the integrity of the ocular surface was scored using slit-lamp microscopy and fluorescein isothiocyanate (FITC) staining. The chemokine CXCL13 was measured by ELISA in sera from Sjögren's syndrome patients (n = 27) and healthy controls (n = 30). Statistical analysis was by the two-tailed, unpaired T-test, or the Mann-Whitney-test for ocular integrity scores.ResultsLTBR blockade for eight weeks reduced B-cell accumulation (approximately 5-fold), eliminated HEV in lacrimal glands, and reduced the entry rate of lymphocytes into lacrimal glands. Affymetrix-chip analysis revealed numerous changes in mRNA expression due to LTBR blockade, including reduction of homeostatic chemokine expression. The reduction of CXCL13, CCL21, CCL19 mRNA and the HEV-associated gene GLYCAM-1 was confirmed by PCR analysis. CXCL13 protein increased with disease progression in lacrimal-gland homogenates, but after LTBR blockade for 8 weeks, CXCL13 was reduced approximately 6-fold to 8.4 pg/mg (+/- 2.7) from 51 pg/mg (+/-5.3) in lacrimal glands of 16 week old control mice. Mice given LTBR blockade exhibited an approximately two-fold greater tear-fluid secretion than control mice (P = 0.001), and had a significantly improved ocular surface integrity score (P = 0.005). The mean CXCL13 concentration in sera from Sjögren's patients (n = 27) was 170 pg/ml, compared to 92.0 pg/ml for sera from (n = 30) healthy controls (P = 0.01).ConclusionsBlockade of LTBR pathways may have therapeutic potential for treatment of Sjögren's syndrome.

Potential Role of CC Chemokines and their Receptors in the Development of Respiratory Diseases

Increasing evidence suggests that the chemokine system coordinates leukocyte migration in immunity and in- flammation, involving in the pathogenesis of many pulmonary diseases. Chemokines are small proteins which interact with specific receptors to exert their chemotactic functions for inflammatory cells and constitutive cells. Among the com- plex system, CC chemokine receptors (CCRs) represent a subfamily of chemokine receptor, which is considered to play an important role in the pathogenesis of diseases characterized by disordered inflammation and immunity, among which some respiratory diseases, such as asthma, chronic obstructive pulmonary disease, acute lung injury, comprise one impor- tant part. The present paper reviewed the research of possible relationship and progress between this system and human lung diseases. Chemokines and their receptors are essential components of Th1- and Th2-mediated responses via the re- cruitment of lymphocytes and macrophages. The local expression of homeostatic chemokines in pulmonary also plays an important role in protective immune responses. Thus, it is important to understand the potential role of CCRs in respira- tory diseases and it may provide exciting new targets for therapeutic intervention.

Tumor immune escape by the loss of homeostatic chemokine expression

The novel keratinocyte-specific chemokine CCL27 plays a critical role in the organization of skin-associated immune responses by regulating T cell homing under homeostatic and inflammatory conditions. Here we demonstrate that human keratinocyte-derived skin tumors may evade T cell-mediated antitumor immune responses by down-regulating the expression of CCL27 through the activation of epidermal growth factor receptor (EGFR)-Ras-MAPK-signaling pathways. Compared with healthy skin, CCL27 mRNA and protein expression was progressively lost in transformed keratinocytes of actinic keratoses and basal and squamous cell carcinomas. In vivo, precancerous skin lesions as well as cutaneous carcinomas showed significantly elevated levels of phosphorylated ERK compared with normal skin, suggesting the activation of EGFR-Ras signaling pathways in keratinocyte-derived malignancies. In vitro, exogenous stimulation of the EGFR-Ras signaling pathway through EGF or transfection of the dominant-active form of the Ras oncogene (H-RasV12) suppressed whereas an EGFR tyrosine kinase inhibitor increased CCL27 mRNA and protein production in keratinocytes. In mice, neutralization of CCL27 led to decreased leukocyte recruitment to cutaneous tumor sites and significantly enhanced primary tumor growth. Collectively, our data identify a mechanism of skin tumors to evade host antitumor immune responses.

Role of CD30 in B/T Segregation in the Spleen

In this report, we identify an important function for CD30 signals in the effective segregation of B and T lymphocytes in the murine spleen, additional to the recognized requirement for lymphotoxin signals. We show that CD30 signals are not required for transcription or protein expression of homeostatic chemokines, but CD30-deficient mice display impaired B/T segregation. This defect correlates with defective expression as detected by Abs of the transmembrane mucin-type protein podoplanin on T zone stroma, although expression at other sites is normal. Defective segregation is not intrinsic to CD30-deficient lymphocytes which segregate normally following transfer into RAG-deficient mice and significantly up-regulate the expression of both CCL21 and podoplanin on T zone stroma of RAG-deficient mice. During development, induction of expression of the CD30 ligand by lymphoid tissue inducer cells and podoplanin by T zone stroma are temporally linked, and the spatial association of these cells suggests that lymphoid tissue inducer cells are capable of providing the CD30 signals. Finally, we show that the appearance of podoplanin on T zone stroma in development is associated with B/T segregation of splenic white pulp areas. Our studies indicate that homeostatic chemokine expression by itself is not sufficient for B/T segregation and our data point to a significant role for podoplanin or molecules associated with podoplanin expressing stroma in the effective segregation of lymphocytes.

Regulation of Homeostatic Chemokine Expression and Cell Trafficking During Immune Responses

The chemokines CCL21 and CXCL13 are immune factors that dictate homing and motility of lymphocytes and dendritic cells in lymphoid tissues. However, the means by which these chemokines are regulated and how they influence cell trafficking during immune responses remain unclear. We show that CCL21 and CXCL13 are transiently down-regulated within lymphoid tissues during immune responses by a mechanism controlled by the cytokine interferon-gamma. This modulation was found to alter the localization of lymphocytes and dendritic cells within responding lymphoid tissues. As a consequence, priming of T cell responses to a second distinct pathogen after chemokine modulation became impaired. We propose that this transient chemokine modulation may help orchestrate local cellularity, thus minimizing competition for space and resources in activated lymphoid tissues.

Leukocytes on Border Patrol

Immune cells move between the circulation system and tissues in response to infection. Upon detection of inflammation, leukocytes initiate a highly orchestrated sequence of events, whereby they attach and roll along on the surface of the endothelium before squeezing through to the underlying tissue. Auffray et al . reveal a quite distinct type of behavior displayed by a population of monocytes that remain attached to the endothelium in the absence of inflammation. The resident cells appeared to survey the surface of postcapillary venules, veins, and arteries, depending on specific chemokine and integrin signals. Upon detection of inflammatory cues, the cells move into infected sites, where they undergo differentiation into macrophages. Mueller et al . reveal how the down-regulation of chemokines in the lymph node prevents T lymphocytes from entering during an ongoing immune response. This delay may help to optimize the lymph node environment to produce the most effective immune response. C. Auffray, D. Fogg, M. Garfa, G. Elain, O. Join-Lambert, S. Kayal, S. Sarnacki, A. Cumano, G. Lauvau, F. Geissmann, Monitoring of blood vessels and tissues by a population of monocytes with patrolling behavior. Science 317 , 666-670 (2007). [Abstract] [Full Text] S. N. Mueller, K. A. Hosiawa-Meagher, B. T. Konieczny, B. M. Sullivan, M. F. Bachmann, R. M. Locksley, R. Ahmed, M. Matloubian, Regulation of homeostatic chemokine expression and cell trafficking during immune responses. Science 317 , 670-674 (2007). [Abstract] [Full Text]

Pulmonary expression of CXC chemokine ligand 13, CC chemokine ligand 19, and CC chemokine ligand 21 is essential for local immunity to influenza

CXC chemokine ligand 13 (CXCL13), CC chemokine ligand 21 (CCL21), and CCL19 are constitutively expressed in secondary lymphoid organs, where they control the placement of lymphocytes and dendritic cells. However, these chemokines are also inducibly expressed in the lung after influenza infection. Here we show that, in the absence of spleen and lymph nodes, the expression of homeostatic chemokines in the lung is essential for local B and T cell responses to influenza and for the development and organization of inducible bronchus-associated lymphoid tissue (iBALT). Surprisingly, despite the association between local CXCL13 expression and the formation of ectopic lymphoid tissues, the loss of CXCL13 in the lung had minimal impact on either the development or function of iBALT. In contrast, the loss of CCL19 and CCL21 impaired iBALT formation as well as B and T cell responses. These results demonstrate that the local expression of homeostatic chemokines in nonlymphoid organs, such as the lung, plays an important role in protective immune responses.

Identification of a Chemokine Network That Recruits FoxP3+ Regulatory T Cells Into Chronically Inflamed Intestine

It has been unclear which chemokine network is involved in migration of T-cell subsets to chronically inflamed lesions of the intestine. SAMP1/YP mice develop a spontaneous chronic transmural intestinal lesion specifically in the ileum. Using these mice, we investigated the gut chemokine network involved in specific migration of T-cell subsets to the inflamed lesion of the intestine. We performed expression analyses of chemokines and their receptors, chemokine receptor blocking studies, and migration studies in vitro and in vivo to identify the gut chemokine network induced in intestinal inflammation and to determine its role in migration of conventional and FoxP3(+) suppressor T cells to the inflamed intestine. The expression of homeostatic chemokines was largely unchanged in the inflamed lesion of SAMP1/YP mice compared with control mice. However, an additional chemokine axis (CCL5-CCR5) was up-regulated in the inflamed intestine of SAMP1/YP mice compared with control mice. Activated T cells of SAMP1/YP mice compared with control mice were hyperresponsive to CCL5 in chemotaxis. CCR5(+) T cells preferentially migrated to the inflamed lesion, which can be blocked by a CCR5 antagonist. Importantly, the FoxP3(+) regulatory T cells of the inflamed lesion of SAMP1/YP mice highly expressed CCR5. CCR5 blockade suppressed the migration of FoxP3(+) T cells into the inflamed intestine and significantly exacerbated the intestinal inflammation. The CCL5-CCR5 chemokine axis is involved in preferential recruitment of FoxP3(+) regulatory T cells, which prevents further exacerbation of chronic inflammation in the intestine.

Simian immunodeficiency virus dramatically alters expression of homeostatic chemokines and dendritic cell markers during infection in vivo

Dendritic cells (DCs) are potent antigen-presenting cells that likely play multiple roles in human immunodeficiency virus type 1 (HIV-1) pathogenesis. We used the simian immunodeficiency virus (SIV)/macaque model to study the effects of infection on homeostatic chemokine expression and DC localization directly in secondary lymphoid tissues. SIV infection altered the expression of chemokines (CCL19/MIP-3beta, CCL21/ 6Ckine, and CCL20/MIP-3alpha) and of chemokine receptors (CCR7 and CCR6) that drive DC trafficking. CCL19/MIP-3beta, CCL20/MIP-3alpha, CCR6, and CCR7 expression increased in lymph nodes during the early systemic burst of viral replication (acute infection), whereas CCL21/6Ckine expression progressively decreased throughout disease to AIDS. Parallel with the SIV-induced perturbations in chemokine expression were changes in the expression of the DC-associated markers, DC-SIGN, DC-LAMP, and DECTIN-1. During AIDS, DC-LAMP mRNA expression levels were significantly reduced in lymph nodes and spleen, and DC-SIGN levels were significantly reduced in spleen. These findings suggest that the disruption of homeostatic chemokine expression is responsible, in part, for alterations in the networks of antigen-presenting cells in lymphoid tissues, ultimately contributing to systemic immunodeficiency.