Protection against inflammation- and autoantibody-caused fetal loss by the chemokine decoy receptor D6.
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ABSTRACT:
SUBMITTER: Martinez de la Torre Y
PROVIDER: S-EPMC1892950 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description: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 alpha, interleukin 1beta, and interferon gamma) 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.
| S-EPMC2526202 | biostudies-other
Project description:The production of pore-forming toxins that disrupt the plasma membrane of host cells is a common virulence strategy for bacterial pathogens such as methicillin-resistant Staphylococcus aureus (MRSA)1-3. It is unclear, however, whether host species possess innate immune mechanisms that can neutralize pore-forming toxins during infection. We previously showed that the autophagy protein ATG16L1 is necessary for protection against MRSA strains encoding α-toxin4-a pore-forming toxin that binds the metalloprotease ADAM10 on the surface of a broad range of target cells and tissues2,5,6. Autophagy typically involves the targeting of cytosolic material to the lysosome for degradation. Here we demonstrate that ATG16L1 and other ATG proteins mediate protection against α-toxin through the release of ADAM10 on exosomes-extracellular vesicles of endosomal origin. Bacterial DNA and CpG DNA induce the secretion of ADAM10-bearing exosomes from human cells as well as in mice. Transferred exosomes protect host cells in vitro by serving as scavengers that can bind multiple toxins, and improve the survival of mice infected with MRSA in vivo. These findings indicate that ATG proteins mediate a previously unknown form of defence in response to infection, facilitating the release of exosomes that serve as decoys for bacterially produced toxins.
| S-EPMC7519780 | biostudies-literature
Project description:RationaleThe D6 chemokine receptor can bind and scavenge several chemokines, including the T-helper 2 (Th2)-associated chemokines CCL17 and CCL22. Although D6 is constitutively expressed in the lung, its pulmonary function is unknown.ObjectivesThis study tested whether D6 regulates pulmonary chemokine levels, inflammation, or airway responsiveness during allergen-induced airway disease.MethodsD6-deficient and genetically matched C57BL/6 mice were sensitized and challenged with ovalbumin. ELISA and flow cytometry were used to measure levels of cytokines and leukocytes, respectively. Mechanical ventilation was used to measure airway reactivity.ResultsThe ability of D6 to diminish chemokine levels in the lung was chemokine concentration dependent. CCL17 and CCL22 were abundant in the airway, and their levels were attenuated by D6 when they were within a defined concentration range. By contrast, airway concentrations of CCL3, CCL5, and CCL11 were low and unaffected by D6. Allergen-challenged D6-deficient mice had more dendritic cells, T cells, and eosinophils in the lung parenchyma and more eosinophils in the airway than similarly challenged C57BL/6 mice. By contrast, D6-deficient mice had reduced airway responses to methacholine compared with C57BL/6 mice. Thus, D6 has opposing effects on inflammation and airway reactivity.ConclusionsThe ability of D6 to scavenge chemokines in the lung is dependent on chemokine concentration. The absence of D6 increases inflammation, but reduces airway reactivity. These findings suggest that inhibiting D6 function might be a novel means to attenuate airway responses in individuals with allergic asthma.
| S-EPMC1899265 | biostudies-literature
Project description:There is much interest in chemokine receptors as therapeutic targets in diseases such as AIDS, autoimmune and inflammatory disorders, and cancer. Hampering such studies is the lack of accurate three-dimensional structural models of these molecules. The CC-chemokine receptor D6 is expressed at exceptionally high levels in heterologous transfectants. Here we report the purification and biochemical characterization of milligram quantities of D6 protein from relatively small cultures of transfected mammalian cells. Importantly, purified D6 retains full functional activity, shown by displaceable binding of 125I-labelled MIP-1beta (macrophage inflammatory protein-1beta) and by complete binding of the receptor to a MIP-1alpha affinity column. In addition, we show that D6 is decorated on the N-terminus by N-linked glycosylation. Mutational analysis reveals that this glycosylation is dispensable for ligand binding and high expression in transfected cells. Metabolic labelling has revealed the receptor to also be sulphated and phosphorylated. Phosphorylation is ligand independent and is not enhanced by ligand binding and internalization, suggesting similarities with the viral chemokine receptor homologue US28. Like US28, an analysis of the full cellular complement of D6 in transfected cells indicates that >80% is found associated with intracellular vesicular structures. This may account for the high quantities of D6 that can be synthesized in these cells. These unusual properties of D6, and the biochemical characterization described here, leads the way towards work aimed at generating the three-dimensional structure of this seven-transmembrane-spanning receptor.
| S-EPMC1224083 | biostudies-other
Project description:BackgroundPre-eclampsia (PE) is a major cause of maternal and perinatal morbidity and mortality worldwide. It is defined by new onset of hypertension and proteinuria after the 20th week of gestation and characterized by systemic exaggerated inflammatory response. D6 is a chemokines scavenger receptor that binds with high affinity CC chemokines, internalizes and targets the ligands for degradation. It is expressed in trophoblast-derived tissues and prevents excessive placenta leukocyte infiltration.The aim of this study was to investigate the expression and function of D6 in human placentae from pre-eclamptic and healthy pregnant women.Methods and resultsPlasma levels of D6-binding CC chemokines (CCL-2, CCL-3, CCL-4, CCL-7, CCL-11) and pro-inflammatory cytokines (IL-6, TNF-?, CRP) were analyzed in 37 healthy pregnant women and 38 patients with PE by multiplex bead assay. Higher circulating levels of CCL7, CCL11, IL-6, (p<0.0001) and CRP (p<0.05) were observed in PE women compared to controls. Levels of circulating CCL4 were decreased in PE (p<0.001), while no significant differences of CCL2, CCL3 or TNF-? levels were detected. Immunofluorescent staining of placental sections showed higher expression of D6 receptor in the PE syncytiotrophoblast. Confocal and Western blot (WB) analyses revealed a prevalent distribution of D6 in trophoblast cells membranes in PE. Increased activation of D6 intracellular pathway was observed by Western blot analyses of p-LIMK and p-cofilin in trophoblast cell lysates. D6 functional assays showed reduced scavenging of CCL2 in PE cells compared to controls. Since actin filaments spatial assembling is essential for D6 intracellular trafficking and scavenging activity, we investigated by confocal microscopy trophoblast cytoskeleton organization and we observed a dramatic disarrangement in PE compared to controls.Conclusionsour results suggest membrane distribution of D6 receptor on trophoblast cell membranes in PE, together with reduced functionality, probably due to cytoskeleton impairment.
| S-EPMC5079655 | biostudies-literature
Project description:ObjectivesRheumatoid arthritis (RA)-specific anti-citrullinated protein/peptide antibodies (ACPAs) appear before disease onset and are associated with bone destruction. We aimed to dissect the role of ACPAs in osteoclast (OC) activation and to identify key cellular mediators in this process.MethodsPolyclonal ACPA were isolated from the synovial fluid (SF) and peripheral blood of patients with RA. Monoclonal ACPAs were isolated from single SF B-cells of patients with RA. OCs were developed from blood cell precursors with or without ACPAs. We analysed expression of citrullinated targets and peptidylarginine deiminases (PAD) enzymes by immunohistochemistry and cell supernatants by cytometric bead array. The effect of an anti-interleukin (IL)-8 neutralising antibody and a pan-PAD inhibitor was tested in the OC cultures. Monoclonal ACPAs were injected into mice and bone structure was analysed by micro-CT before and after CXCR1/2 blocking with reparixin.ResultsProtein citrullination by PADs is essential for OC differentiation. Polyclonal ACPAs enhance OC differentiation through a PAD-dependent IL-8-mediated autocrine loop that is completely abolished by IL-8 neutralisation. Some, but not all, human monoclonal ACPAs derived from single SF B-cells of patients with RA and exhibiting distinct epitope specificities promote OC differentiation in cell cultures. Transfer of the monoclonal ACPAs into mice induced bone loss that was completely reversed by the IL-8 antagonist reparixin.ConclusionsWe provide novel insights into the key role of citrullination and PAD enzymes during OC differentiation and ACPA-induced OC activation. Our findings suggest that IL8-dependent OC activation may constitute an early event in the initiation of the joint specific inflammation in ACPA-positive RA.
| S-EPMC4819614 | biostudies-literature
Project description:Proinflammatory CC chemokines control leukocyte recruitment and function during inflammation by engaging chemokine receptors expressed on circulating leukocytes. The D6 chemokine receptor can bind several of these chemokines, but appears unable to couple to signal transduction pathways or direct cell migration. Instead, D6 has been proposed to act as a chemokine scavenger, removing proinflammatory chemokines to dampen leukocyte responses. In this study, we have examined the role of D6 in the colon using the dextran sodium sulfate-induced model of colitis. We show that D6 is expressed in the resting colon, predominantly by stromal cells and B cells, and is up-regulated during colitis. Unexpectedly, D6-deficient mice showed reduced susceptibility to colitis and had less pronounced clinical symptoms associated with this model. D6 deletion had no impact on the level of proinflammatory CC chemokines released from cultured colon explants, or on the balance of leukocyte subsets recruited to the inflamed colon. However, late in colitis, inflamed D6-deficient colons showed enhanced production of several proinflammatory cytokines, including IFN-gamma and IL-17A, and there was a marked increase in IL-17A-secreting gammadelta T cells in the lamina propria. Moreover, Ab-mediated neutralization of IL-17A worsened the clinical symptoms of colitis at these later stages of the response in D6-deficient, but not wild-type, mice. Thus, D6 can contribute to the development of colitis by regulating IL-17A secretion by gammadelta T cells in the inflamed colon.
| S-EPMC2786198 | biostudies-literature
Project description:The encapsulated bacteria Streptococcus pneumoniae, Neisseria meningitis, Haemophilus influenzae, and Streptococcus agalactiae (Group B Streptococcus) have been responsible for the majority of severe infections in children for decades, specifically bacteremia and meningitis. Isolates which cause invasive disease are usually surrounded by a polysaccharide capsule, which is a major virulence factor and the key antigen in protective protein-polysaccharide conjugate vaccines. Protection against these bacteria is largely mediated via polysaccharide-specific antibody and complement, although the contribution of these and other components, and the precise mechanisms, vary between species and include opsonophagocytosis and complement-dependent bacteriolysis. Further studies are required to more precisely elucidate mechanisms of protection against non-type b H. influenzae and Group B Streptococcus.
| S-EPMC6255856 | biostudies-other
Project description:The exposure of skin to ultraviolet (UV) radiation results in sunburn cell (SBC) and cyclobutane pyrimidine dimer (CPD) formation and local immune suppression. However, the pathways that regulate these events are poorly understood. Here, we exposed mice to UVB to study the early cytotoxic effects in absence of E3 ubiquitin protein ligase Cbl-b. We observed that Cbl-b-/- mice developed significantly less SBCs and CPDs compared to WT mice. In addition, microarray analysis revealed that loss of Cbl-b-induced cell tolerance genes rather than DNA repair genes. Taken together, our results suggest a novel role of Cbl-b in regulating UV cytotoxicity.
2018-08-15 | GSE79073 | GEO
Project description:Red cell transfusions are associated with the development of acute lung injury in the critically ill. Recent evidence suggests that storage induced alterations of the red blood cell (RBC) collectively termed the "storage lesion" may be linked with adverse biologic consequences. Using a 2-event model of systemic endotoxemia followed by a secondary challenge of RBC transfusion, we investigated whether purified RBC concentrates from syngeneic C57BL/6 mice altered inflammatory responses in murine lungs. Transfusion of RBCs stored for 10 days increased neutrophil counts, macrophage inflammatory protein-2 (MIP-2) and chemokine (KC) concentrations in the airspaces, and lung microvascular permeability compared with transfusion of less than 1-day-old RBCs. Because RBCs have been shown to scavenge inflammatory chemokines through the blood group Duffy antigen, we investigated the expression and function of Duffy during storage. In banked human RBCs, both Duffy expression and chemokine scavenging function were reduced with increasing duration of storage. Transfusion of Duffy knockout RBCs into Duffy wild-type endotoxemic mice increased airspace neutrophils, inflammatory cytokine concentrations, and lung microvascular permeability compared with transfusion of Duffy wild-type RBCs. Thus, reduction in erythrocyte chemokine scavenging is one functional consequence of the storage lesion by which RBC transfusion can augment existing lung inflammation.
| S-EPMC2635081 | biostudies-other