RESUMO
Aging is associated with dysregulated immune functions. Here, we investigated the impact of age on neutrophil diapedesis. Using confocal intravital microscopy, we found that in aged mice, neutrophils adhered to vascular endothelium in inflamed tissues but exhibited a high frequency of reverse transendothelial migration (rTEM). This retrograde breaching of the endothelium by neutrophils was governed by enhanced production of the chemokine CXCL1 from mast cells that localized at endothelial cell (EC) junctions. Increased EC expression of the atypical chemokine receptor 1 (ACKR1) supported this pro-inflammatory milieu in aged venules. Accumulation of CXCL1 caused desensitization of the chemokine receptor CXCR2 on neutrophils and loss of neutrophil directional motility within EC junctions. Fluorescent tracking revealed that in aged mice, neutrophils undergoing rTEM re-entered the circulation and disseminated to the lungs where they caused vascular leakage. Thus, neutrophils stemming from a local inflammatory site contribute to remote organ damage, with implication to the dysregulated systemic inflammation associated with aging.
Assuntos
Envelhecimento/imunologia , Transporte Biológico/imunologia , Inflamação/imunologia , Neutrófilos/imunologia , Animais , Quimiocina CXCL1/imunologia , Células Endoteliais/imunologia , Endotélio Vascular/imunologia , Feminino , Junções Intercelulares/imunologia , Pulmão/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Receptores de Interleucina-8B/imunologia , Vênulas/imunologiaRESUMO
Healthy individuals of African ancestry have neutropenia that has been linked with the variant rs2814778(G) of the gene encoding atypical chemokine receptor 1 (ACKR1). This polymorphism selectively abolishes the expression of ACKR1 in erythroid cells, causing a Duffy-negative phenotype. Here we describe an unexpected fundamental role for ACKR1 in hematopoiesis and provide the mechanism that links its absence with neutropenia. Nucleated erythroid cells had high expression of ACKR1, which facilitated their direct contact with hematopoietic stem cells. The absence of erythroid ACKR1 altered mouse hematopoiesis including stem and progenitor cells, which ultimately gave rise to phenotypically distinct neutrophils that readily left the circulation, causing neutropenia. Individuals with a Duffy-negative phenotype developed a distinct profile of neutrophil effector molecules that closely reflected the one observed in the ACKR1-deficient mice. Thus, alternative physiological patterns of hematopoiesis and bone marrow cell outputs depend on the expression of ACKR1 in the erythroid lineage, findings with major implications for the selection advantages that have resulted in the paramount fixation of the ACKR1 rs2814778(G) polymorphism in Africa.
Assuntos
Sistema do Grupo Sanguíneo Duffy , Eritroblastos , Hematopoese , Células-Tronco Hematopoéticas , Neutropenia , Neutrófilos , Receptores de Superfície Celular , Animais , Humanos , Camundongos , População Negra/genética , Medula Óssea/patologia , Células da Medula Óssea/metabolismo , Proliferação de Células , Sistema do Grupo Sanguíneo Duffy/genética , Sistema do Grupo Sanguíneo Duffy/metabolismo , Eritroblastos/metabolismo , Citometria de Fluxo , Imunofluorescência , Hematopoese/genética , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/metabolismo , Microscopia Confocal , Neutropenia/genética , Neutrófilos/citologia , Neutrófilos/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Receptores de Quimiocinas/genética , Receptores de Quimiocinas/metabolismoRESUMO
Neutrophils require directional cues to navigate through the complex structure of venular walls and into inflamed tissues. Here we applied confocal intravital microscopy to analyze neutrophil emigration in cytokine-stimulated mouse cremaster muscles. We identified differential and non-redundant roles for the chemokines CXCL1 and CXCL2, governed by their distinct cellular sources. CXCL1 was produced mainly by TNF-stimulated endothelial cells (ECs) and pericytes and supported luminal and sub-EC neutrophil crawling. Conversely, neutrophils were the main producers of CXCL2, and this chemokine was critical for correct breaching of endothelial junctions. This pro-migratory activity of CXCL2 depended on the atypical chemokine receptor 1 (ACKR1), which is enriched within endothelial junctions. Transmigrating neutrophils promoted a self-guided migration response through EC junctions, creating a junctional chemokine "depot" in the form of ACKR1-presented CXCL2 that enabled efficient unidirectional luminal-to-abluminal migration. Thus, CXCL1 and CXCL2 act in a sequential manner to guide neutrophils through venular walls as governed by their distinct cellular sources.
Assuntos
Quimiocina CXCL1 , Quimiocina CXCL2 , Sistema do Grupo Sanguíneo Duffy , Neutrófilos , Receptores de Superfície Celular , Migração Transendotelial e Transepitelial , Animais , Músculos Abdominais/efeitos dos fármacos , Músculos Abdominais/imunologia , Músculos Abdominais/metabolismo , Quimiocina CXCL1/genética , Quimiocina CXCL1/imunologia , Quimiocina CXCL1/metabolismo , Quimiocina CXCL2/genética , Quimiocina CXCL2/imunologia , Quimiocina CXCL2/metabolismo , Sistema do Grupo Sanguíneo Duffy/genética , Sistema do Grupo Sanguíneo Duffy/imunologia , Sistema do Grupo Sanguíneo Duffy/metabolismo , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/imunologia , Células Endoteliais/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Junções Intercelulares/efeitos dos fármacos , Junções Intercelulares/imunologia , Junções Intercelulares/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Neutrófilos/citologia , Neutrófilos/imunologia , Neutrófilos/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/imunologia , Receptores de Superfície Celular/metabolismo , Migração Transendotelial e Transepitelial/efeitos dos fármacos , Migração Transendotelial e Transepitelial/genética , Migração Transendotelial e Transepitelial/imunologia , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
Afferent lymph-borne dendritic cells essentially rely on the chemokine receptor CCR7 for their transition from the subcapsular lymph node sinus into the parenchyma, a migratory step driven by putative gradients of CCR7 ligands. We found that lymph node fringes indeed contained physiological gradients of the chemokine CCL21, which depended on the expression of CCRL1, the atypical receptor for the CCR7 ligands CCL19 and CCL21. Lymphatic endothelial cells lining the ceiling of the subcapsular sinus, but not those lining the floor, expressed CCRL1, which scavenged chemokines from the sinus lumen. This created chemokine gradients across the sinus floor and enabled the emigration of dendritic cells. In vitro live imaging revealed that spatially confined expression of CCRL1 was necessary and sufficient for the creation of functional chemokine gradients.
Assuntos
Quimiocina CCL21/fisiologia , Linfonodos/imunologia , Receptores CCR/fisiologia , Animais , Movimento Celular , Células Dendríticas/fisiologia , Camundongos , Camundongos Endogâmicos C57BLRESUMO
Atypical chemokine receptors (ACKRs) scavenge chemokines and can contribute to gradient formation by binding, internalizing, and delivering chemokines for lysosomal degradation. ACKRs do not couple to G-proteins and fail to induce typical signaling induced by chemokine receptors. ACKR3, which binds and scavenges CXCL12 and CXCL11, is known to be expressed in vascular endothelium, where it has immediate access to circulating chemokines. ACKR4, which binds and scavenges CCL19, CCL20, CCL21, CCL22, and CCL25, has also been detected in lymphatic and blood vessels of secondary lymphoid organs, where it clears chemokines to facilitate cell migration. Recently, GPR182, a novel ACKR-like scavenger receptor, has been identified and partially deorphanized. Multiple studies point towards the potential coexpression of these 3 ACKRs, which all interact with homeostatic chemokines, in defined cellular microenvironments of several organs. However, an extensive map of ACKR3, ACKR4, and GPR182 expression in mice has been missing. In order to reliably detect ACKR expression and coexpression, in the absence of specific anti-ACKR antibodies, we generated fluorescent reporter mice, ACKR3GFP/+, ACKR4GFP/+, GPR182mCherry/+, and engineered fluorescently labeled ACKR-selective chimeric chemokines for in vivo uptake. Our study on young healthy mice revealed unique and common expression patterns of ACKRs in primary and secondary lymphoid organs, small intestine, colon, liver, and kidney. Furthermore, using chimeric chemokines, we were able to detect distinct zonal expression and activity of ACKR4 and GPR182 in the liver, which suggests their cooperative relationship. This study provides a broad comparative view and a solid stepping stone for future functional explorations of ACKRs based on the microanatomical localization and distinct and cooperative roles of these powerful chemokine scavengers.
Assuntos
Transdução de Sinais , Animais , Camundongos , Quimiocina CCL19/metabolismo , Movimento CelularRESUMO
Atypical chemokine receptors (ACKRs) are a group of seven-transmembrane spanning serpentine receptors that are structurally homologous to classical G-protein-coupled receptors and bind cognate chemokines with high affinities but do not signal via G-proteins or mediate cell migration. However, ACKRs efficiently modify the availability and function of chemokines in defined microanatomical environments, can signal via intracellular effectors other than G-proteins, and play complex roles in physiology and disease, including in cancer. In this review, we summarize the findings on the diverse contributions of individual ACKRs to cancer development, progression, and tumor-host interactions. We discuss how changes in ACKR expression within tumor affect cancer growth, tumor vascularization, leukocyte infiltration, and metastasis formation, ultimately resulting in differential disease outcomes. Across many studies, ACKR3 expression was shown to support tumor growth and dissemination, whereas ACKR1, ACKR2, and ACKR4 in tumors were more likely to contribute to tumor suppression. With few notable exceptions, the insights on molecular and cellular mechanisms of ACKRs activities in cancer remain sparse, and the intricacies of their involvement are not fully appreciated. This is particularly true for ACKR1, ACKR2 and ACKR4. A better understanding of how ACKR expression and functions impact cancer should pave the way for their future targeting by new and effective therapies.
Assuntos
Neoplasias , Humanos , Neoplasias/patologia , Quimiocinas/metabolismo , Transdução de Sinais , Neovascularização Patológica , Proteínas de Ligação ao GTP/metabolismoRESUMO
The Duffy antigen receptor for chemokines (DARC) belongs to a family of 'silent' heptahelical chemokine receptors that do not couple to G proteins and fail to transmit measurable intracellular signals. DARC binds most inflammatory chemokines and is prominently expressed on venular endothelial cells, where its function has remained contentious. Here we show that DARC, like other silent receptors, internalized chemokines but did not effectively scavenge them. Instead, DARC mediated chemokine transcytosis, which led to apical retention of intact chemokines and more leukocyte migration across monolayers expressing DARC. Mice overexpressing DARC on blood vessel endothelium had enhanced chemokine-induced leukocyte extravasation and contact-hypersensitivity reactions. Thus, interactions of chemokines with DARC support their activity on apposing leukocytes in vitro and in vivo.
Assuntos
Movimento Celular , Quimiocinas/metabolismo , Sistema do Grupo Sanguíneo Duffy/metabolismo , Leucócitos/imunologia , Receptores de Superfície Celular/metabolismo , Animais , Células Cultivadas , Cães , Sistema do Grupo Sanguíneo Duffy/genética , Endotélio Vascular/imunologia , Endotélio Vascular/metabolismo , Humanos , Camundongos , Transporte Proteico , Receptores de Superfície Celular/genéticaRESUMO
Succinate acts as an extracellular mediator signaling through the G protein-coupled receptor GPR91. Here we show that dendritic cells had high expression of GPR91. In these cells, succinate triggered intracellular calcium mobilization, induced migratory responses and acted in synergy with Toll-like receptor ligands for the production of proinflammatory cytokines. Succinate also enhanced antigen-specific activation of human and mouse helper T cells. GPR91-deficient mice had less migration of Langerhans cells to draining lymph nodes and impaired tetanus toxoid-specific recall T cell responses. Furthermore, GPR91-deficient allografts elicited weaker transplant rejection than did the corresponding grafts from wild-type mice. Our results suggest that the succinate receptor GPR91 is involved in sensing immunological danger, which establishes a link between immunity and a metabolite of cellular respiration.
Assuntos
Células Dendríticas/imunologia , Receptores Acoplados a Proteínas G/agonistas , Receptores Acoplados a Proteínas G/imunologia , Ácido Succínico/metabolismo , Linfócitos T/imunologia , Animais , Linhagem Celular Tumoral , Movimento Celular , Citocinas/biossíntese , Células Dendríticas/metabolismo , Rejeição de Enxerto/imunologia , Humanos , Células de Langerhans/citologia , Linfonodos/imunologia , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos SCID , Receptores de Antígenos de Linfócitos T/agonistas , Receptores de Antígenos de Linfócitos T/antagonistas & inibidores , Receptores de Antígenos de Linfócitos T/imunologia , Receptores Acoplados a Proteínas G/genética , Transdução de Sinais/imunologia , Ácido Succínico/farmacologia , Linfócitos T Auxiliares-Indutores/imunologia , Regulação para CimaRESUMO
The recruitment of lymphocytes via the hepatic sinusoidal channels and positioning within liver tissue is a critical event in the development and persistence of chronic inflammatory liver diseases. The hepatic sinusoid is a unique vascular bed lined by hepatic sinusoidal endothelial cells (HSECs), a functionally and phenotypically distinct subpopulation of endothelial cells. Using flow-based adhesion assays to study the migration of lymphocytes across primary human HSECs, we found that lymphocytes enter into HSECs, confirmed by electron microscopy demonstrating clear intracellular localization of lymphocytes in vitro and by studies in human liver tissues. Stimulation by interferon-γ increased intracellular localization of lymphocytes within HSECs. Furthermore, using confocal imaging and time-lapse recordings, we demonstrated "intracellular crawling" of lymphocytes entering into one endothelial cell from another. This required the expression of intracellular adhesion molecule-1 and stabilin-1 and was facilitated by the junctional complexes between HSECs. CONCLUSION: Lymphocyte migration is facilitated by the unique structure of HSECs. Intracellular crawling may contribute to optimal lymphocyte positioning in liver tissue during chronic hepatitis. (Hepatology 2017;65:294-309).
Assuntos
Capilares/citologia , Movimento Celular , Células Endoteliais/fisiologia , Linfócitos/fisiologia , Citoplasma , Endotélio Vascular/citologia , Humanos , Fígado/irrigação sanguíneaRESUMO
BACKGROUND: Intravascular leukocyte recruitment in most vertebrate tissues is restricted to postcapillary and collecting venules, whereas capillaries and arterioles usually support little or no leukocyte adhesion. This segmental restriction is thought to be mediated by endothelial, rather than hemodynamic, differences. The underlying mechanisms are largely unknown, in part because effective tools to distinguish, isolate, and analyze venular endothelial cells (V-ECs) and non-venular endothelial cells (NV-ECs) have been unavailable. We hypothesized that the atypical chemokine receptor DARC (Duffy Antigen Receptor for Chemokines, a.k.a. ACKR1 or CD234) may distinguish V-ECs versus NV-ECs in mice. METHODS: We generated a rat-anti-mouse monoclonal antibody (MAb) that specifically recognizes the erythroid and endothelial forms of native, surface-expressed DARC. Using this reagent, we characterized DARC expression and distribution in the microvasculature of murine tissues. RESULTS: DARC was exquisitely restricted to post-capillary and small collecting venules and completely absent from arteries, arterioles, capillaries, veins, and most lymphatics in every tissue analyzed. Accordingly, intravital microscopy showed that adhesive leukocyte-endothelial interactions were restricted to DARC+ venules. DARC was detectable over the entire circumference of V-ECs, but was more concentrated at cell-cell junctions. Analysis of single-cell suspensions suggested that the frequency of V-ECs among the total microvascular EC pool varies considerably between different tissues. CONCLUSIONS: Immunostaining of endothelial DARC allows the identification and isolation of intact V-ECs from multiple murine tissues. This strategy may be useful to dissect the mechanisms underlying segmental microvascular specialization in healthy and diseased tissues and to characterize the role of EC subsets in tissue-homeostasis, immune surveillance, infection, inflammation, and malignancies.
Assuntos
Sistema do Grupo Sanguíneo Duffy , Células Endoteliais , Endotélio Vascular , Regulação da Expressão Gênica , Camundongos , Receptores de Superfície Celular , Animais , Camundongos/genética , Camundongos/metabolismo , Sistema do Grupo Sanguíneo Duffy/genética , Sistema do Grupo Sanguíneo Duffy/metabolismo , Células Endoteliais/citologia , Células Endoteliais/metabolismo , Endotélio Vascular/citologia , Endotélio Vascular/metabolismo , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Veias/metabolismoRESUMO
Sixteen years ago, the Nomenclature Committee of the International Union of Pharmacology approved a system for naming human seven-transmembrane (7TM) G protein-coupled chemokine receptors, the large family of leukocyte chemoattractant receptors that regulates immune system development and function, in large part by mediating leukocyte trafficking. This was announced in Pharmacological Reviews in a major overview of the first decade of research in this field [Murphy PM, Baggiolini M, Charo IF, Hébert CA, Horuk R, Matsushima K, Miller LH, Oppenheim JJ, and Power CA (2000) Pharmacol Rev 52:145-176]. Since then, several new receptors have been discovered, and major advances have been made for the others in many areas, including structural biology, signal transduction mechanisms, biology, and pharmacology. New and diverse roles have been identified in infection, immunity, inflammation, development, cancer, and other areas. The first two drugs acting at chemokine receptors have been approved by the U.S. Food and Drug Administration (FDA), maraviroc targeting CCR5 in human immunodeficiency virus (HIV)/AIDS, and plerixafor targeting CXCR4 for stem cell mobilization for transplantation in cancer, and other candidates are now undergoing pivotal clinical trials for diverse disease indications. In addition, a subfamily of atypical chemokine receptors has emerged that may signal through arrestins instead of G proteins to act as chemokine scavengers, and many microbial and invertebrate G protein-coupled chemokine receptors and soluble chemokine-binding proteins have been described. Here, we review this extended family of chemokine receptors and chemokine-binding proteins at the basic, translational, and clinical levels, including an update on drug development. We also introduce a new nomenclature for atypical chemokine receptors with the stem ACKR (atypical chemokine receptor) approved by the Nomenclature Committee of the International Union of Pharmacology and the Human Genome Nomenclature Committee.
Assuntos
Receptores de Quimiocinas , Animais , Proteínas de Artrópodes/genética , Proteínas de Artrópodes/metabolismo , Humanos , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Receptores de Quimiocinas/classificação , Receptores de Quimiocinas/genética , Receptores de Quimiocinas/metabolismo , Terminologia como Assunto , Carrapatos , Proteínas Virais/genética , Proteínas Virais/metabolismoRESUMO
Thymus colonisation and thymocyte positioning are regulated by interactions between CCR7 and CCR9, and their respective ligands, CCL19/CCL21 and CCL25. The ligands of CCR7 and CCR9 also interact with the atypical receptor CCRL1 (also known as ACKR4), which is expressed in the thymus and has recently been reported to play an important role in normal αßT-cell development. Here, we show that CCRL1 is expressed within the thymic cortex, predominantly by MHC-II(low) CD40(-) cortical thymic epithelial cells and at the subcapsular zone by a population of podoplanin(+) thymic epithelial cells in mice. Interestingly, CCRL1 is also expressed by stromal cells which surround the pericytes of vessels at the corticomedullary junction, the site for progenitor cell entry and mature thymocyte egress from the thymus. We show that CCRL1 suppresses thymocyte progenitor entry into the thymus, however, the thymus size and cellularity are the same in adult WT and CCRL1(-/-) mice. Moreover, CCRL1(-/-) mice have no major perturbations in T-cell populations at different stages of thymic differentiation and development, and have a similar rate of thymocyte migration into the blood. Collectively, our findings argue against a major role for CCRL1 in normal thymus development and function.
Assuntos
Células Epiteliais/metabolismo , Linfopoese/genética , Receptores CCR/genética , Células Estromais/metabolismo , Timócitos/metabolismo , Timo/metabolismo , Animais , Antígenos CD40/deficiência , Antígenos CD40/genética , Antígenos CD40/imunologia , Diferenciação Celular , Movimento Celular , Microambiente Celular , Células Epiteliais/citologia , Células Epiteliais/imunologia , Feminino , Regulação da Expressão Gênica no Desenvolvimento/imunologia , Masculino , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/imunologia , Camundongos , Camundongos Knockout , Pericitos/citologia , Pericitos/imunologia , Receptores CCR/deficiência , Receptores CCR/imunologia , Receptores CCR7/genética , Receptores CCR7/imunologia , Transdução de Sinais , Células-Tronco/citologia , Células-Tronco/imunologia , Células Estromais/citologia , Células Estromais/imunologia , Timócitos/citologia , Timócitos/imunologia , Timo/citologia , Timo/crescimento & desenvolvimento , Timo/imunologiaRESUMO
Macrophage migration-inhibitory factor (MIF) is a pleiotropic cytokine with chemokine-like functions and is a mediator in numerous inflammatory conditions. Depending on the context, MIF signals through 1 or more of its receptors cluster of differentiation (CD)74, CXC-motif chemokine receptor (CXCR)2, and CXCR4. In addition, heteromeric receptor complexes have been identified. We characterized the atypical chemokine receptor CXCR7 as a novel receptor for MIF. MIF promoted human CXCR7 internalization up to 40%, peaking at 50-400 nM and 30 min, but CXCR7 internalization by MIF was not dependent on CXCR4. Yet, by coimmunoprecipitation, fluorescence microscopy, and a proximity ligation assay, CXCR7 was found to engage in MIF receptor complexes with CXCR4 and CD74, both after ectopic overexpression and in endogenous conditions in a human B-cell line. Receptor competition binding and coimmunoprecipitation studies combined with sulfo-SBED-biotin-transfer provided evidence for a direct interaction between MIF and CXCR7. Finally, we demonstrated MIF/CXCR7-mediated functional responses. Blockade of CXCR7 suppressed MIF-mediated ERK- and zeta-chain-associated protein kinase (ZAP)-70 activation (from 2.1- to 1.2-fold and from 2.5- to 1.6-fold, respectively) and fully abrogated primary murine B-cell chemotaxis triggered by MIF, but not by CXCL12. B cells from Cxcr7(-/-) mice exhibited an ablated transmigration response to MIF, indicating that CXCR7 is essential for MIF-promoted B-cell migration. Our findings provide biochemical and functional evidence that MIF is an alternative ligand of CXCR7 and suggest a functional role of the MIF-CXCR7 axis in B-lymphocyte migration.
Assuntos
Linfócitos B/metabolismo , Quimiotaxia/fisiologia , Oxirredutases Intramoleculares/metabolismo , Sistema de Sinalização das MAP Quinases/fisiologia , Fatores Inibidores da Migração de Macrófagos/metabolismo , Receptores CXCR/metabolismo , Proteína-Tirosina Quinase ZAP-70/metabolismo , Animais , Linfócitos B/citologia , Linhagem Celular Tumoral , Quimiocina CXCL12/genética , Quimiocina CXCL12/metabolismo , Humanos , Oxirredutases Intramoleculares/genética , Fatores Inibidores da Migração de Macrófagos/genética , Camundongos , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Receptores CXCR/genética , Receptores CXCR4/genética , Receptores CXCR4/metabolismo , Proteína-Tirosina Quinase ZAP-70/genéticaRESUMO
Endothelial surface microstructures have been described previously under inflammatory conditions; however, they remain ill-characterized. In this study, CXCL8, an inflammatory chemokine, was shown to induce the formation of filopodia-like protrusions on endothelial cells; the same effects were observed with CXCL10 and CCL5. Chemokines stimulated filopodia formation by both microvascular (from bone marrow and skin) and macrovascular (from human umbilical vein) endothelial cells. Use of blocking Abs and degradative enzymes demonstrated that CXCL8-stimulated filopodia formation was mediated by CXCR1 and CXCR2, Duffy Ag/receptor for chemokines, heparan sulfate (HS), and syndecans. HS was present on filopodial protrusions appearing as a meshwork on the cell surface, which colocalized with CXCL8, and this glycosaminoglycan was 2,6-O- and 3-O-sulfated. Transmission electron microscopy revealed that CXCL8-stimulated filopodial and microvilli-like protrusions that interacted with leukocytes before transendothelial migration and removal of HS reduced this migration. iTRAQ mass spectrometry showed that changes in the levels of cytoskeletal, signaling, and extracellular matrix proteins were associated with CXCL8-stimulated filopodia/microvilli formation; these included tropomyosin, fascin, and Rab7. This study suggests that chemokines stimulate endothelial filopodia and microvilli formation, leading to their presentation to leukocytes and leukocyte transendothelial migration.
Assuntos
Células Apresentadoras de Antígenos/imunologia , Células Apresentadoras de Antígenos/metabolismo , Endotélio Vascular/imunologia , Endotélio Vascular/metabolismo , Interleucina-8/metabolismo , Linhagem Celular Transformada , Linhagem Celular Tumoral , Células Cultivadas , Quimiocina CCL5/metabolismo , Quimiocina CXCL10/metabolismo , Endotélio Vascular/citologia , Células Endoteliais da Veia Umbilical Humana , Humanos , Leucócitos/citologia , Leucócitos/imunologia , Leucócitos/metabolismo , Microcirculação/imunologia , Propriedades de Superfície , Migração Transendotelial e Transepitelial/imunologiaRESUMO
Chemokines, acting on their cognate receptors on infiltrating leukocytes, drive the inflammatory response. We have been interested in determining roles and potential mechanisms for the atypical chemokine-scavenging receptor D6 in the regulation of inflammation. In this study, we show that a psoriasis-like pathology that arises in inflamed skins of D6-deficient mice is characterized by a massive and aberrant localization of neutrophils to the dermal/epidermal junction, which is associated with development of the pathology. Such misplacement of neutrophils is also seen with D6-deficient mice in other inflammatory models, suggesting a role for D6 in the spatial positioning of neutrophils within inflamed sites. We further show that D6 functions cell autonomously in this context and that D6, expressed by neutrophils, limits their migrational responses to CCR1 ligands such as CCL3. Our data therefore indicate that D6 is able to play a cell-autonomous role as a migratory rheostat restricting migration of D6-expressing cells such as neutrophils toward ligands for coexpressed inflammatory chemokine receptors. These data have important implications for our understanding of the roles for D6 in regulating inflammation and for our understanding of the control of spatial positioning of leukocytes at inflamed sites.
Assuntos
Doenças do Sistema Imunitário/imunologia , Transtornos Leucocíticos/imunologia , Psoríase/imunologia , Receptores de Quimiocinas/imunologia , Animais , Modelos Animais de Doenças , Inflamação/imunologia , Camundongos , Camundongos Knockout , Microscopia Confocal , Psoríase/patologia , Pele/imunologia , Pele/patologiaRESUMO
The Duffy antigen/receptor for chemokines, DARC, belongs to the family of atypical heptahelical chemokine receptors that do not couple to G proteins and therefore fail to transmit conventional intracellular signals. Here we show that during experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis, the expression of DARC is upregulated at the blood-brain barrier. These findings are corroborated by the presence of a significantly increased number of subcortical white matter microvessels staining positive for DARC in human multiple sclerosis brains as compared to control tissue. Using an in vitro blood-brain barrier model we demonstrated that endothelial DARC mediates the abluminal to luminal transport of inflammatory chemokines across the blood-brain barrier. An involvement of DARC in experimental autoimmune encephalomyelitis pathogenesis was confirmed by the observed ameliorated experimental autoimmune encephalomyelitis in Darc(-/-) C57BL/6 and SJL mice, as compared to wild-type control littermates. Experimental autoimmune encephalomyelitis studies in bone marrow chimeric Darc(-/-) and wild-type mice revealed that increased plasma levels of inflammatory chemokines in experimental autoimmune encephalomyelitis depended on the presence of erythrocyte DARC. However, fully developed experimental autoimmune encephalomyelitis required the expression of endothelial DARC. Taken together, our data show a role for erythrocyte DARC as a chemokine reservoir and that endothelial DARC contributes to the pathogenesis of experimental autoimmune encephalomyelitis by shuttling chemokines across the blood-brain barrier.
Assuntos
Barreira Hematoencefálica , Quimiocinas , Sistema do Grupo Sanguíneo Duffy , Encefalomielite Autoimune Experimental , Esclerose Múltipla , Receptores de Superfície Celular , Regulação para Cima , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Antígenos CD/metabolismo , Barreira Hematoencefálica/metabolismo , Barreira Hematoencefálica/fisiopatologia , Permeabilidade Capilar/genética , Sistema Nervoso Central/imunologia , Sistema Nervoso Central/metabolismo , Sistema Nervoso Central/patologia , Cerebelo/metabolismo , Quimiocinas/genética , Quimiocinas/metabolismo , Modelos Animais de Doenças , Sistema do Grupo Sanguíneo Duffy/metabolismo , Encefalomielite Autoimune Experimental/sangue , Encefalomielite Autoimune Experimental/induzido quimicamente , Encefalomielite Autoimune Experimental/patologia , Encefalomielite Autoimune Experimental/fisiopatologia , Endotélio Vascular/metabolismo , Endotélio Vascular/patologia , Técnicas In Vitro , Camundongos Endogâmicos C57BL , Camundongos Knockout , Esclerose Múltipla/patologia , Receptores de Superfície Celular/deficiência , Receptores de Superfície Celular/metabolismo , Regulação para Cima/genéticaRESUMO
The inflammatory response is normally limited by mechanisms regulating its resolution. In the absence of resolution, inflammatory pathologies can emerge, resulting in substantial morbidity and mortality. We have been studying the D6 chemokine scavenging receptor, which played an indispensable role in the resolution phase of inflammatory responses and does so by facilitating removal of inflammatory CC chemokines. In D6-deficient mice, otherwise innocuous cutaneous inflammatory stimuli induce a grossly exaggerated inflammatory response that bears many similarities to human psoriasis. In the present study, we have used transcriptomic approaches to define the molecular make up of this response. The data presented highlight potential roles for a number of cytokines in initiating and maintaining the psoriasis-like pathology. Most compellingly, we provide data indicating a key role for the type I interferon pathway in the emergence of this pathology. Neutralizing antibodies to type I interferons are able to ameliorate the psoriasis-like pathology, confirming a role in its development. Comparison of transcriptional data generated from this mouse model with equivalent data obtained from human psoriasis further demonstrates the strong similarities between the experimental and clinical systems. As such, the transcriptional data obtained in this preclinical model provide insights into the cytokine network active in exaggerated inflammatory responses and offer an excellent tool to evaluate the efficacy of compounds designed to therapeutically interfere with inflammatory processes.
Assuntos
Interferon Tipo I/metabolismo , Psoríase/imunologia , Receptores CCR10/genética , Animais , Feminino , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Interferon Tipo I/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Análise de Sequência com Séries de Oligonucleotídeos , Ésteres de Forbol/toxicidade , Psoríase/induzido quimicamente , Psoríase/genética , Psoríase/patologia , Transcrição Gênica , Receptor D6 de QuimiocinaRESUMO
Antibody-forming cells (AFCs) expressing the chemokine receptor CXCR3 are recruited to sites of inflammation where they help clear pathogens but may participate in autoimmune diseases. Here we identify a mechanism that induces CXCR3 expression by AFC and germinal center (GC) B cells. This happens when CD8 T cells are recruited into CD4 T cell-dependent B-cell responses. Ovalbumin-specific CD4 T cells (OTII) were transferred alone or with ovalbumin-specific CD8 T cells (OTI) and the response to subcutaneous alum-precipitated ovalbumin was followed in the draining lymph nodes. OTII cells alone induce T helper 2-associated class switching to IgG1, but few AFC or GC B cells express CXCR3. By contrast, OTI-derived IFN-γ induces most responding GC B cells and AFCs to express high levels of CXCR3, and diverse switching to IgG2a, IgG2b, with some IgG1. Up-regulation of CXCR3 by GC B cells and AFCs and their migration toward its ligand CXCL10 are shown to depend on B cells' intrinsic T-bet, a transcription factor downstream of the IFN-γR signaling. This model clarifies how precursors of long-lived AFCs and memory B cells acquire CXCR3 that causes their migration to inflammatory foci.
Assuntos
Linfócitos B/imunologia , Linfócitos T CD8-Positivos/imunologia , Movimento Celular/imunologia , Receptores CXCR3/imunologia , Proteínas com Domínio T/imunologia , Vacinas/imunologia , Transferência Adotiva , Compostos de Alúmen , Animais , Linfócitos B/metabolismo , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD4-Positivos/transplante , Linfócitos T CD8-Positivos/metabolismo , Linfócitos T CD8-Positivos/transplante , Diferenciação Celular/imunologia , Quimiocina CXCL10/imunologia , Quimiocina CXCL10/metabolismo , Citometria de Fluxo , Centro Germinativo/imunologia , Centro Germinativo/metabolismo , Imunização/métodos , Interferon gama/imunologia , Interferon gama/metabolismo , Ligantes , Camundongos , Camundongos Endogâmicos C57BL , Ovalbumina/imunologia , Receptores CXCR3/genética , Receptores CXCR3/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteínas com Domínio T/genética , Proteínas com Domínio T/metabolismo , Células Th2/imunologia , Células Th2/metabolismo , Regulação para Cima/genéticaRESUMO
CCR7-mediated migration of naive T cells into the secondary lymphoid organs is a prerequisite for their encounter with mature dendritic cells, the productive presentation of cognate antigen, and consequent T cell proliferation and effector differentiation. Therefore, CCR7 was suggested to play an important role in the initiation of adaptive immune responses. In this study, we show that primary immunity can also develop in the absence of CCR7. Moreover, CCR7-deficient knockout (KO) mice display augmented immune responses. Our data cumulatively suggest that enhanced immunity in CCR7 KO mice is caused by the defective lymph node (LN) positioning of FoxP3(+) CD4(+) CD25(+) regulatory T cells (T reg cells) and the consequent impediment of their function. The FoxP3(+) T reg cells express CCR7 and, after their adoptive transfer, migrate into the LNs of wild-type mice. Here, they proliferate in situ upon antigen stimulation and inhibit the generation of antigen-specific T cells. Conversely, transferred CCR7-deficient T reg cells fail to migrate into the LNs and suppress antigen-induced T cell responses. The transfer of combinations of naive and T reg cells from wild-type and CCR7 KO mice into syngeneic severe combined immunodeficient mice directly demonstrates that CCR7-deficient T reg cells are less effective than their wild-type counterparts in preventing the development of inflammatory bowel disease.