Chemokine Decoy Receptor D6 Research Articles

Abnormal uterine inflammation in obstetric syndromes: molecular insights into the role of chemokine decoy receptor D6 and inflammasome NLRP3.

The adaptation of the uterine environment into a favorable immunological and inflammatory milieu is a physiological process needed in normal pregnancy. A uterine hyperinflammatory state, whether idiopathic or secondary to hormonal or organic uterine disorders (polycystic ovary syndromes, endometriosis/adenomyosis and fibroids), negatively influences the interactions between decidua and trophoblast, early in gestation, and between chorion and decidua later in pregnancy. Abnormal activation of uterine inflammatory pathways not only contributes to the pathogenesis of the obstetric syndromes, i.e. recurrent pregnancy loss (RPL), pre-term delivery (PTD) and pre-eclampsia (PE), but also to correlates with severity. In this review, we summarize recent advances in the knowledge of uterine molecular mechanisms of inflammatory modulation in normal pregnancy and obstetric syndromes (RPL, PTD and PE). In particular, we focus on two regulators of uterine/placental inflammation: the NLRP3 inflammasome and the chemokines decoy receptor D6. We performed comprehensive review of the literature in PubMed and Google Scholar databases from 1994 to 2018. The available evidence suggests that: (i) the expression of inflammasome NLRP3 is increased in the endometrium of women with unexplained RPL, in the chorioamniotic membranes of women with PTL and in the placenta of women with PE; (ii) there is a role for abnormal expression and function of D6 decoy receptor at the feto-maternal interface in cases of RPL and PTD and (iii) the function of placental D6 decoy receptor is impaired in PE. A wider comprehension of the inflammatory molecular mechanisms involved in the pathogenesis of the obstetric syndromes might lead to the identification of new potential therapeutic targets.

Proinflammatory CX3CR1+CD59+Tumor Necrosis Factor-Like Molecule 1A+Interleukin-23+ Monocytes Are Expanded in Patients With Ankylosing Spondylitis and Modulate Innate Lymphoid Cell 3 Immune Functions.

Gut-derived innate lymphoid cell 3 (ILC3) has been shown to participate in the pathogenesis of ankylosing spondylitis (AS). CX3 CR1+ mononuclear phagocytes (MNPs) have been demonstrated to modulate ILC3 function in the gut. This study was undertaken to investigate the role of proinflammatory CX3 CR1+CD59+ MNPs in modulating ILC3 function in AS patients. MNP subsets in the blood of AS patients and controls were analyzed by flow cytometry. The presence of CX3 CR1+CD59+ cells in tissue was confirmed by confocal microscopy. Expression of the proinflammatory chemokines CX3 CL1 and CCL2 and decoy receptor 6 (DcR-6) was analyzed. Peripheral CX3 CR1+CD59+ cells were cocultured with ILC3, and changes in their frequency were evaluated by flow cytometry. Transcriptome analysis of circulating CX3 CR1+ monocytes was also performed. DcR-6 deficiency and CCL2 overexpression were observed in inflamed tissues from AS patients. In the gut, the proinflammatory CX3 CR1+CD59+ MNP population was expanded, correlated with the presence of bacteria, and produced high levels of tumor necrosis factor-like molecule 1A (TL1A) and interleukin-23 (IL-23). MNPs positive for CD11b, CD11c, and major histocompatibility complex class II, predominantly expressing CX3 CR1, were also expanded in the small intestines of treatment-naive SKG relative to BALB/c mice. The frequency of gut-derived CX3 CR1+CD59+CCR9+TL1A+IL-23+ MNPs was significantly higher in the peripheral blood and synovial fluid of AS patients than controls. CCR9+CX3 CR1+CD59+ monocytes were also expanded in AS synovial and bone marrow samples. Transcriptome analysis of isolated CX3 CR1+CD59+ monocytes demonstrated a specific proinflammatory profile in AS. Isolated proinflammatory CX3 CR1+CD59+ MNPs from AS patients induced the expansion and activation of ILC3. Proinflammatory CX3 CR1+CD59+TL1A+IL-23+ MNPs are expanded in AS patients and display a specific proinflammatory transcriptome profile. Given the ability of these cells to support ILC3 expansion, they may promote a sustained proinflammatory status in AS.

Intermediate monocytes lead to enhanced myocardial remodelling in STEMI patients with diabetes.

This study aimed to evaluate the potential associations of intermediate monocytes (CD14(++)CD16(+)) with myocardial remodelling in ST segment elevation myocardial infarction (STEMI) patients with diabetes.A total of 67 STEMI patients with diabetes were enrolled. The control group consisted of 65 STEMI patients without diabetes. All patients received emergency medical services for reperfusion therapy in less than 12 hours after onset of AMI. Blinded to patient clinical characteristics, monocyte subset analysis was performed using flow cytometry immediately after admission. mRNA of Chemokine Decoy Receptor D6 in each subset of monocytes was validated by Q-PCR. Expression of CCL2 in patient plasma was determined with an Elisa kit. Infarct size and left ventricular ejection fraction (LVEF) were measured using 3-dimensional echocardiography 3 days and 6 months after AMI. The incidences of recurrent cardiovascular events and death in each group were measured using the Kaplan-Meier estimator in follow-up during the next 24 months. Cox proportional-hazard models were further used to analyze the relationship of monocyte cell counts and event-free survival after adjusting for confounding factors.The number of circulating intermediate monocytes was significantly correlated with LVEF% and infarct size (r = -0.32; P = 0.008; r = 0.57, P < 0.001) in STEMI patients with diabetes compared with those without diabetes 6 months after AMI. Chemokine Decoy Receptor D6 transcript levels were lower in intermediate monocytes of STEMI patients with diabetes compared to the subsets in STEMI patients without diabetes (P < 0.001). Higher levels of CCL2 (pg/mL) were observed in STEMI patients with diabetes compared to STEMI patients without diabetes (P < 0.001). During a mean follow-up period of 24 ± 1 month, recurrent cardiovascular events or death occurred in 23 patients belonging to the STEMI with diabetes group and 10 belonging to the control group. Univariate Kaplan-Meier analysis revealed that counts of the intermediate monocytes according to median showed statistical significance in STEMI patients with diabetes (P = 0.010). After full adjustment for confounding factors, the cells were found to remain independently related to recurrent cardiovascular events or death in this group (P = 0.004, 95% CI: 1.62-12.49).Intermediate monocytes were associated with LV remodelling in STEMI patients with diabetes. The cells were predictive for recurrent cardiovascular events or death in these patients. A low level of D6 mRNA in the intermediate monocytes of STEMI patients with diabetes and high level of CCL2 in these patients may partially explain the causality.

Macrophages.

Macrophages.

Expression of the chemokine decoy receptor D6 is decreased in colon adenocarcinomas.

Recruitment of immune cells to tumors is a complex process crucial for both inflammation-driven tumor progression and specific anti-tumor cytotoxicity. Chemokines control the directed migration of immune cells, and their actions are partly controlled by nonsignaling chemokine decoy receptors. The role of the receptors such as D6, Duffy antigen receptor for chemokines and ChemoCentryx chemokine receptor in immunity to tumors is still unclear. Using real-time PCR, we detected significantly decreased expression of D6 mRNA in colon tumors compared to unaffected mucosa. D6 protein was expressed by lymphatic endothelium and mononuclear cells in the colon lamina propria and detected by immunohistochemistry in two out of six tissue samples containing high D6 mRNA levels, whereas no staining was observed in any tissue samples expressing low mRNA levels. When examining the density of lymphatic vessels in colon tumors, we detected a marked increase in vessels identified by the lymphatic endothelial marker Lyve-1, excluding passive regulation of D6 due to decreased lymphatic vessel density. In parallel, the Treg-recruiting chemokine CCL22, which is sequestered by D6, was threefold increased in tumor tissue. Furthermore, we could show that low D6 expression correlated to more invasive tumors and that tumor location influences D6 expression, which is lower in the more distal parts of the colon. The data support that regulation of D6 by colon tumors results in altered levels of proinflammatory CC chemokines, thereby shaping the local chemokine network to favor tumor survival. This may have implications for the design of future immunotherapy for colon cancer.

The Chemokine Decoy Receptor D6 Prevents Excessive Inflammation and Adverse Ventricular Remodeling After Myocardial Infarction

Leukocyte infiltration in ischemic areas is a hallmark of myocardial infarction, and overwhelming infiltration of innate immune cells has been shown to promote adverse remodeling and cardiac rupture. Recruitment of inflammatory cells in the ischemic heart depends highly on the family of CC-chemokines and their receptors. Here, we hypothesized that the chemokine decoy receptor D6, which specifically binds and scavenges inflammatory CC-chemokines, might limit inflammation and adverse cardiac remodeling after infarction. D6 was expressed in human and murine infarcted myocardium. In a murine model of myocardial infarction, D6 deficiency led to increased chemokine (C-C motif) ligand 2 and chemokine (C-C motif) ligand 3 levels in the ischemic heart. D6-deficient (D6(-/-)) infarcts displayed increased infiltration of pathogenic neutrophils and Ly6Chi monocytes, associated with strong matrix metalloproteinase-9 and matrix metalloproteinase-2 activities in the ischemic heart. D6(-/-) mice were cardiac rupture prone after myocardial infarction, and functional analysis revealed that D6(-/-) hearts had features of adverse remodeling with left ventricle dilation and reduced ejection fraction. Bone marrow chimera experiments showed that leukocyte-borne D6 had no role in this setting, and that leukocyte-specific chemokine (C-C motif) receptor 2 deficiency rescued the adverse phenotype observed in D6(-/-) mice. We show for the first time that the chemokine decoy receptor D6 limits CC-chemokine-dependent pathogenic inflammation and is required for adequate cardiac remodeling after myocardial infarction.

Transgenic expression of murine chemokine decoy receptor D6 by islets reveals the role of inflammatory CC chemokines in the development of autoimmune diabetes in NOD mice

Autoimmune diabetes results from a progressive destruction of insulin-producing beta cells in the pancreatic islets by chemokine-attracted lymphocytes. Because islet cells in NOD mice produce chemokines during the development of autoimmune diabetes, we investigated the role of inflammatory CC chemokines in disease progression in these mice. We generated a transgenic NOD mouse model that overproduces the inflammatory CC chemokine decoy receptor D6 in pancreatic islets. The frequency of diabetes and insulitis scores of transgenic mice were decreased significantly, compared with non-transgenic control littermates. Transgenic expression of D6 (also known as Ccbp2) did not affect systemic lymphocyte development or alter: (1) the T cell subsets such as T helper (Th)1, Th2 and T regulatory cells; or (2) antigen-presenting cells such as dendritic cells or macrophages. The percentages and numbers of T and B lymphocytes were decreased significantly in the pancreas. Activation status, autoantigen-specific proliferation and diabetogenicity of lymphocytes were also markedly reduced. Inflammatory CC chemokines play a critical role in the development of autoimmune diabetes. Transgenic expression of D6 in pancreatic islets of NOD mice reduced this pathogenic process by suppressing activation of autoreactive lymphocytes and by reducing migration of lymphocytes to the pancreas.

Novel Players in Female Fertility: The Long Pentraxin PTX3 and the Chemokine Decoy Receptor D6

The foetal-maternal interaction results in the induction of a local inflammatory response and a state of systemic inflammation. Several factors are involved in successful embryonic implantation, including hormones, growth factors, cytokines, chemokines, adhesion molecules, extracellular matrix components, and matrix-degrading enzymes. The enriched cytokine milieu associated to implantation is likely to control trophoblast migration and differentiation, leukocyte influx and activation, complement activation, as well as angiogenic and angiostatic processes in the implantation site. Finally, these mediators play a key role in tuning the immune responses to protect the foetus from infections as well as from maternal rejection. Here, the role of two new players involved in regulating inflammation at the maternal-foetal interface will be discussed: the long pentraxin PTX3 and the decoy receptor for inflammatory chemokines D6.

Inflammatory bowel disease and intestinal cancer: a paradigm of the Yin–Yang interplay between inflammation and cancer

Colon cancer represents a paradigm for the connection between inflammation and cancer in terms of epidemiology and mechanistic studies in preclinical models. Key components of cancer promoting inflammation include master transcription factors (for example, nuclear factor kappaB, STAT3), proinflammatory cytokines (for example, tumor necrosis factor, interleukin-6 (IL-6)), cyclooxygenase-2 and selected chemokines (for example, CCL2). Of no less importance are mediators that keep inflammation in check, including IL-10, transforming growth factorbeta, toll-like receptor and the IL-1 receptor inhibitor TIR8/SIGIRR, and the chemokine decoy and scavenger receptor D6. Dissection of molecular pathways involved in colitis-associated cancer may offer opportunities for innovative therapeutic strategies.

The lymphatic system controls intestinal inflammation and inflammation-associated colon cancer through the chemokine decoy receptor D6

Background and aimsInflammatory CC chemokines have long been associated with cancer, but unequivocal evidence of a role in clinically relevant models of carcinogenesis is lacking. D6, a promiscuous decoy receptor...

Recognition Versus Adaptive Up-regulation and Degradation of CC Chemokines by the Chemokine Decoy Receptor D6 Are Determined by Their N-terminal Sequence

The chemokine decoy receptor D6 controls inflammatory responses by selective recognition and degradation of most CCR1 to CCR5 agonistic ligands. CCL14 is a homeostatic chemokine present at high concentrations in the serum with a weak agonist activity on CCR1. Under inflammatory conditions, plasmin and UPA-mediated truncation of 8 amino acids generates the potent CCR1/CCR3/CCR5 isoform CCL14(9-74), which is further processed and inactivated by dipeptidyl peptidase IV/CD26 that generates CCL14(11-74). Here we report that D6 efficiently binds both CCL14 and its truncated isoforms. Like other D6 ligands, the biologically active CCL14(9-74) induces adaptive up-regulation of D6 expression on the cell membrane and is rapidly and efficiently degraded. In contrast, the D6-mediated degradation of the biologically inactive isoforms CCL14(1-74) and CCL14(11-74) is very inefficient. Thus, D6 cooperates with CD26 in the negative regulation of CCL14 by the selective degradation of its biologically active isoform. Analysis of a panel of CC chemokines and their truncated isoforms revealed that D6-mediated chemokine degradation does not correlate with binding affinity. Conversely, degradation efficiency is positively correlated with D6 adaptive up-regulation. Sequence analysis indicated that a proline residue in position 2 of D6 ligands is dispensable for binding but crucial for D6 adaptive up-regulation and efficient degradation.

The chemokine scavenging receptor D6 limits acute toxic liver injury in vivo

The chemokine decoy receptor D6 is a promiscuous chemokine receptor lacking classical signaling functions. It negatively regulates inflammation by targeting CC chemokines to cellular internalization and degradation. Here we analyze the function of D6 in acute CCl(4)-induced liver damage in constitutive D6(-/-) and wild-type mice. The degree of liver injury was assessed by liver histology, serum transaminases, IL-6, and TNFalpha mRNA expression. Protein levels of D6 ligands (CCL2, CCL3, CCL5) and the non-D6-ligand CXCL9 within the livers were determined by ELISAs. The intrahepatic infiltration of immune cells was characterized by FACS. Genetic deletion of D6 led to prolonged liver damage after acute CCl(4) administration. The augmented liver damage in D6(-/-) mice was associated with increased protein levels of intrahepatic inflammatory chemokines CCL2, CCL3, and CCL5 after 48 h, whereas CXCL9 was not different between knockout and wild-type mice. Functionally, increased intra-hepatic CC chemokine concentrations led to increased infiltration of CD45(+) leukocytes, which were mainly identified as T and NK cells. In conclusion, the chemokine scavenger receptor D6 has a non-redundant role in acute toxic liver injury in vivo. These results support the importance of post-translational chemokine regulation and describe a new mechanism of immune modulation within the liver.

4 - The lymphatic system controls intestinal inflammation and inflammation-associated colon cancer through the chemokine decoy receptor D6

4 - The lymphatic system controls intestinal inflammation and inflammation-associated colon cancer through the chemokine decoy receptor D6

Hemopoietic cell expression of the chemokine decoy receptor D6 is dynamic and regulated by GATA1

D6 scavenges inflammatory chemokines and is essential for the regulation of inflammatory and immune responses. Mechanisms explaining the cellular basis for D6 function have been based on D6 expression by lymphatic endothelial cells. In this study, we demonstrate that functional D6 is also expressed by murine and human hemopoietic cells and that this expression can be regulated by pro- and anti-inflammatory agents. D6 expression was highest in B cells and dendritic cells (DCs). In myeloid cells, LPS down-regulated expression, while TGF-beta up-regulated expression. Activation of T cells with anti-CD3 and soluble CD28 up-regulated mRNA expression 20-fold, while maturation of human macrophage and megakaryocyte precursors also up-regulated D6 expression. Competition assays demonstrated that chemokine uptake was D6 dependent in human leukocytes, whereas mouse D6-null cells failed to uptake and clear inflammatory chemokines. Furthermore, we present evidence indicating that D6 expression is GATA1 dependent, thus explaining D6 expression in myeloid progenitor cells, mast cells, megakaryocytes, and DCs. We propose a model for D6 function in which leukocytes, within inflamed sites, activate D6 expression and thus trigger resolution of inflammatory responses. Our data on D6 expression by circulating DCs and B cells also suggest alternative roles for D6, perhaps in the coordination of innate and adaptive immune responses. These data therefore alter our models of in vivo D6 function and suggest possible discrete, and novel, roles for D6 on lymphatic endothelial cells and leukocytes.

Hemopoietic Cell Expression of the Chemokine Decoy Receptor D6 Is Dynamic and Regulated by GATA1

D6 scavenges inflammatory chemokines and is essential for the regulation of inflammatory and immune responses. Mechanisms explaining the cellular basis for D6 function have been based on D6 expression by lymphatic endothelial cells. In this study, we demonstrate that functional D6 is also expressed by murine and human hemopoietic cells and that this expression can be regulated by pro- and anti-inflammatory agents. D6 expression was highest in B cells and dendritic cells (DCs). In myeloid cells, LPS down-regulated expression, while TGF-beta up-regulated expression. Activation of T cells with anti-CD3 and soluble CD28 up-regulated mRNA expression 20-fold, while maturation of human macrophage and megakaryocyte precursors also up-regulated D6 expression. Competition assays demonstrated that chemokine uptake was D6 dependent in human leukocytes, whereas mouse D6-null cells failed to uptake and clear inflammatory chemokines. Furthermore, we present evidence indicating that D6 expression is GATA1 dependent, thus explaining D6 expression in myeloid progenitor cells, mast cells, megakaryocytes, and DCs. We propose a model for D6 function in which leukocytes, within inflamed sites, activate D6 expression and thus trigger resolution of inflammatory responses. Our data on D6 expression by circulating DCs and B cells also suggest alternative roles for D6, perhaps in the coordination of innate and adaptive immune responses. These data therefore alter our models of in vivo D6 function and suggest possible discrete, and novel, roles for D6 on lymphatic endothelial cells and leukocytes.

Role of the chemokine decoy receptor D6 in balancing inflammation, immune activation, and antimicrobial resistance in Mycobacterium tuberculosis infection

D6 is a decoy and scavenger receptor for inflammatory CC chemokines. D6-deficient mice were rapidly killed by intranasal administration of low doses of Mycobacterium tuberculosis. The death of D6−/− mice was associated with a dramatic local and systemic inflammatory response with levels of M. tuberculosis colony-forming units similar to control D6-proficient mice. D6-deficient mice showed an increased numbers of mononuclear cells (macrophages, dendritic cells, and CD4 and CD8 T lymphocytes) infiltrating inflamed tissues and lymph nodes, as well as abnormal increased concentrations of CC chemokines (CCL2, CCL3, CCL4, and CCL5) and proinflammatory cytokines (tumor necrosis factor α, interleukin 1β, and interferon γ) in bronchoalveolar lavage and serum. High levels of inflammatory cytokines in D6−/− infected mice were associated with liver and kidney damage, resulting in both liver and renal failure. Blocking inflammatory CC chemokines with a cocktail of antibodies reversed the inflammatory phenotype of D6−/− mice but led to less controlled growth of M. tuberculosis. Thus, the D6 decoy receptor plays a key role in setting the balance between antimicrobial resistance, immune activation, and inflammation in M. tuberculosis infection.

Chemokine Decoy Receptor D6 Plays a Negative Role in Human Breast Cancer

Chemokine binding protein D6 is a promiscuous decoy receptor that can inhibit inflammation in vivo; however, the role it plays in cancer is not well known yet. In this study, we showed for the first time that human breast cancer differentially expressed D6 and the expression could be regulated by some cytokines. More importantly, overexpression of D6 in human breast cancer cells inhibits proliferation and invasion in vitro and tumorigenesis and lung metastasis in vivo. This inhibition is associated with decreased chemokines (e.g., CCL2 and CCL5), vessel density, and tumor-associated macrophage infiltration. Furthermore, D6 expression is inversely correlated to lymph node metastasis as well as clinical stages, but positively correlated to disease-free survival rate in cancer patients. Therefore, D6 plays a negative role in the growth and metastasis of breast cancer.

A Review of Molecular Contrasts Between Arresting and Viable Porcine Attachment Sites

Significant spontaneous fetal loss of unknown cause occurs in North American commercial swine. About 30% of conceptuses, thought to be genetically normal, are lost during the peri-attachment period. An additional 20% are lost at mid-pregnancy. Littermate endometrial and trophoblast biopsies were studied by quantitative real-time PCR for gene expression, and immunohistochemistry for protein expression at gestation day (gd)15-23 and 50. RNA analyses were also conducted on endometrial lymphocytes and arterial endothelial cells removed from biopsies by laser capture microdissection. Genes were selected for study from human literature and cloned as required. As in humans, angiogenic, cytokine, chemokine and chemokine decoy receptor gene expression occurs at the porcine maternal-fetal interface. In each tissue studied, distinct patterns of expression are found between early and mid-pregnancy, as well as between viable and arresting conceptus attachment sites. These changes involve both endometrial lymphocytes and dendritic cells. Restriction in endometrial angiogenesis, reduction in expression of the chemokine decoy receptor D6, and reduction in dendritic cell numbers contribute to fetal arrest. In peri-attachment loss, interferon-gamma is more abundantly transcribed than tumor necrosis factor-alpha, but this ratio is reversed during midgestation failure. Further characterization of spontaneous fetal loss in pigs will identify targets for modification by hog producers and may provide a model for identification of antecedents to fetal loss in humans.

Role of the Maternal or Fetal Chemokine Decoy Receptor D6 in Protection against Inflammation‐included Fetal Loss

Role of the Maternal or Fetal Chemokine Decoy Receptor D6 in Protection against Inflammation‐included Fetal Loss

Rab11-dependent ligand-induced upregulation of the chemokine decoy receptor D6

Rab11-dependent ligand-induced upregulation of the chemokine decoy receptor D6