RESUMO
Spontaneous organ hemorrhage is the major complication in thrombocytopenia with a potential fatal outcome. However, the exact mechanisms regulating vascular integrity are still unknown. Here, we demonstrate that neutrophils recruited to inflammatory sites are the cellular culprits inducing thrombocytopenic tissue hemorrhage. Exposure of thrombocytopenic mice to UVB light provokes cutaneous petechial bleeding. This phenomenon is also observed in immune-thrombocytopenic patients when tested for UVB tolerance. Mechanistically, we show, analyzing several inflammatory models, that it is neutrophil diapedesis through the endothelial barrier that is responsible for the bleeding defect. First, bleeding is triggered by neutrophil-mediated mechanisms, which act downstream of capturing, adhesion, and crawling on the blood vessel wall and require Gαi signaling in neutrophils. Second, mutating Y731 in the cytoplasmic tail of VE-cadherin, known to selectively affect leukocyte diapedesis, but not the induction of vascular permeability, attenuates bleeding. Third, and in line with this, simply destabilizing endothelial junctions by histamine did not trigger bleeding. We conclude that specifically targeting neutrophil diapedesis through the endothelial barrier may represent a new therapeutic avenue to prevent fatal bleeding in immune-thrombocytopenic patients.
Assuntos
Antígenos CD/genética , Caderinas/genética , Dermatite de Contato/patologia , Hemorragia/fisiopatologia , Neutrófilos/fisiologia , Trombocitopenia/fisiopatologia , Migração Transendotelial e Transepitelial/fisiologia , Vasculite/patologia , Análise de Variância , Animais , Dermatite de Contato/etiologia , Dermatite de Contato/imunologia , Citometria de Fluxo , Hemorragia/etiologia , Hemorragia/prevenção & controle , Técnicas Histológicas , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Mutação de Sentido Incorreto/genética , Migração Transendotelial e Transepitelial/efeitos dos fármacos , Raios Ultravioleta , Vasculite/etiologia , Vasculite/imunologiaRESUMO
Tissue loss after myocardial ischemia with reperfusion (MI/R) is in part conveyed by neutrophil recruitment to post-ischemic myocardium. Strategies to prevent reperfusion injury would help to limit myocardial damage. The receptor for activated complement factor 5 (C5aR) plays a prominent role in inflammation. We examine the effects of C5aR-deficiency on reperfusion injury after MI/R. C5aR(-/-)-mice and their C57BL/6- (WT) littermates underwent transient myocardial ischemia followed by different time points of reperfusion. Infarct size and leukocyte infiltration were determined. Expression of C5aR, inflammatory cytokines and adhesion molecules were analyzed by real-time RT-PCR. Leukocyte-endothelial interactions were assessed by low-shear adhesion- and transmigration-assays in vitro. Myocardial C5aR mRNA expression was 2.8-fold increased by ischemia. Infarct size per area-at-risk and leukocyte recruitment into infarctions were reduced in C5aR(-/-)-compared to WT-mice as well as in WT mice treated with the C5aR-antagonist JPE1375. IL-6, IL-1ß, ICAM-1 and VCAM-1 expression were not different, while TNFα expression was reduced in C5aR(-/-)-mice after MI/R. In vitro, C5aR on leukocytes is required for effective transendothelial migration but not adhesion. Expression of MMP9 and JAM-A, molecules that are involved in leukocyte transmigration, were reduced in C5aR(-/-) mice in vivo. Genetic C5aR deficiency blunts the inflammatory response in murine MI/R resulting in reduced inflammatory cell recruitment, which is due to a C5aR-dependent effect on leukocyte transmigration across inflamed endothelium into the ischemic myocardium. This effect could be related to MMP9- and JAM-A expression in response to ischemia and reperfusion.
Assuntos
Infarto do Miocárdio/imunologia , Traumatismo por Reperfusão Miocárdica/complicações , Miocárdio/metabolismo , Neutrófilos/imunologia , Receptor da Anafilatoxina C5a/metabolismo , Animais , Moléculas de Adesão Celular/genética , Moléculas de Adesão Celular/metabolismo , Movimento Celular/genética , Células Cultivadas , Regulação da Expressão Gênica/genética , Humanos , Metaloproteinase 9 da Matriz/genética , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Infarto do Miocárdio/complicações , Traumatismo por Reperfusão Miocárdica/etiologia , Miocárdio/imunologia , Miocárdio/patologia , Receptor da Anafilatoxina C5a/genética , Receptor da Anafilatoxina C5a/imunologia , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Migração Transendotelial e Transepitelial/genética , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Various heterotrimeric G(i) proteins are considered to be involved in cell migration and effector function of immune cells. The underlying mechanisms, how they control the activation of myeloid effector cells, are not well understood. To elucidate isoform-redundant and -specific roles for Gα(i) proteins in these processes, we analyzed mice genetically deficient in Gα(i2) or Gα(i3). First, we show an altered distribution of tissue macrophages and blood monocytes in the absence of Gα(i2) but not Gα(i3). Gα(i2)-deficient but not wild-type or Gα(i3)-deficient mice exhibited reduced recruitment of macrophages in experimental models of thioglycollate-induced peritonitis and LPS-triggered lung injury. In contrast, genetic ablation of Gα(i2) had no effect on Gα(i)-dependent peritoneal cytokine production in vitro and the phagocytosis-promoting function of the Gα(i)-coupled C5a anaphylatoxin receptor by liver macrophages in vivo. Interestingly, actin rearrangement and CCL2- and C5a anaphylatoxin receptor-induced chemotaxis but not macrophage CCR2 and C5a anaphylatoxin receptor expression were reduced in the specific absence of Gα(i2). Furthermore, knockdown of Gα(i2) caused decreased cell migration and motility of RAW 264.7 cells, which was rescued by transfection of Gα(i2) but not Gα(i3). These results indicate that Gα(i2), albeit redundant to Gα(i3) in some macrophage activation processes, clearly exhibits a Gα(i) isoform-specific role in the regulation of macrophage migration.
Assuntos
Inibição de Migração Celular/imunologia , Subunidade alfa Gi2 de Proteína de Ligação ao GTP/deficiência , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/deficiência , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/fisiologia , Macrófagos/imunologia , Macrófagos/patologia , Lesão Pulmonar Aguda/imunologia , Lesão Pulmonar Aguda/patologia , Animais , Inibição de Migração Celular/genética , Subunidade alfa Gi2 de Proteína de Ligação ao GTP/genética , Lipopolissacarídeos/toxicidade , Macrófagos/metabolismo , Camundongos , Camundongos da Linhagem 129 , Camundongos Knockout , Monócitos/imunologia , Monócitos/patologia , Peritonite/induzido quimicamente , Peritonite/imunologia , Peritonite/patologia , Tioglicolatos/toxicidadeRESUMO
BACKGROUND: Receptor binding of complement C5a leads to proinflammatory activation of many cell types, but the role of receptor-mediated action during arterial remodeling after injury has not been studied. In the present study, we examined the contribution of the C5a receptor (C5aR) to neointima formation in apolipoprotein E-deficient mice employing a C5aR antagonist (C5aRA) and a C5aR-blocking monoclonal antibody. METHODS AND RESULTS: Mice fed an atherogenic diet were subjected to wire-induced endothelial denudation of the carotid artery and treated with C5aRA and anti-C5aR-blocking monoclonal antibody or vehicle control. Compared with controls, neointima formation was significantly reduced in mice receiving C5aRA or anti-C5aR-blocking monoclonal antibody for 1 week but not for 3 weeks, attributable to an increased content of vascular smooth muscle cells, whereas a marked decrease in monocyte and neutrophil content was associated with reduced vascular cell adhesion molecule-1. As assessed by immunohistochemistry, reverse transcription polymerase chain reaction, and flow cytometry, C5aR was expressed in lesional and cultured vascular smooth muscle cells, upregulated by injury or tumor necrosis factor-alpha, and reduced by C5aRA. Plasma levels and neointimal plasminogen activator inhibitor-1 peaked 1 week after injury and were downregulated in C5aRA-treated mice. In vitro, C5a induced plasminogen activator inhibitor-1 expression in endothelial cells and vascular smooth muscle cells in a C5aRA-dependent manner, possibly accounting for higher vascular smooth muscle cell immigration. CONCLUSIONS: One-week treatment with C5aRA or anti-C5aR-blocking monoclonal antibody limited neointimal hyperplasia and inflammatory cell content and was associated with reduced vascular cell adhesion molecule-1 expression. However, treatment for 3 weeks failed to reduce but rather stabilized plaques, likely by reducing vascular plasminogen activator inhibitor-1 and increasing vascular smooth muscle cell migration.
Assuntos
Anticorpos Monoclonais/farmacologia , Aterosclerose/tratamento farmacológico , Aterosclerose/metabolismo , Músculo Liso Vascular/efeitos dos fármacos , Oligopeptídeos/farmacologia , Receptor da Anafilatoxina C5a/antagonistas & inibidores , Animais , Apolipoproteínas E/genética , Aterosclerose/patologia , Lesões das Artérias Carótidas/tratamento farmacológico , Lesões das Artérias Carótidas/metabolismo , Lesões das Artérias Carótidas/patologia , Movimento Celular/efeitos dos fármacos , Movimento Celular/imunologia , Complemento C5a/metabolismo , Modelos Animais de Doenças , Citometria de Fluxo , Leucócitos/citologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Mutantes , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patologia , Receptor da Anafilatoxina C5a/genética , Receptor da Anafilatoxina C5a/imunologia , Serpina E2 , Serpinas/metabolismo , Túnica Íntima/efeitos dos fármacos , Túnica Íntima/imunologia , Túnica Íntima/patologia , Molécula 1 de Adesão de Célula Vascular/metabolismoRESUMO
Vaccination against Pseudomonas aeruginosa is a desirable, yet challenging strategy for prevention of airway infection in patients with cystic fibrosis. We compared the formation of antibodies in lower airways induced by systemic and mucosal vaccination strategies. We immunised 48 volunteers in six vaccination groups with either a systemic, a nasal, or four newly constructed oral live vaccines based on attenuated live Salmonella (strains CVD908 and Ty21a), followed by a systemic booster vaccination. All vaccines were based on a recombinant fusion protein of the highly conserved P. aeruginosa outer membrane proteins OprF and OprI as antigen. While systemic and mucosal vaccines induced a comparable rise of serum antibody titers, a significant rise of IgA and IgG antibodies in the lower airways was noted only after nasal and oral vaccinations. We conclude that nasal and oral OprF-OprI vaccines are promising candidates for development of antipseudomonal immunisation through inducing a specific antibody response in the lung.
Assuntos
Infecções por Pseudomonas/prevenção & controle , Vacinas contra Pseudomonas/imunologia , Pseudomonas aeruginosa/imunologia , Administração Intranasal , Administração Oral , Adulto , Anticorpos Antibacterianos/análise , Anticorpos Antibacterianos/sangue , Proteínas da Membrana Bacteriana Externa/genética , Proteínas da Membrana Bacteriana Externa/imunologia , Líquido da Lavagem Broncoalveolar/imunologia , Feminino , Vetores Genéticos , Experimentação Humana , Humanos , Imunização Secundária/métodos , Imunoglobulina A/análise , Imunoglobulina G/análise , Masculino , Pessoa de Meia-Idade , Vacinas contra Pseudomonas/administração & dosagem , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/imunologia , Sistema Respiratório/imunologia , Salmonella/genética , Vacinação/métodos , Vacinas Atenuadas/administração & dosagem , Vacinas Atenuadas/imunologia , Adulto JovemRESUMO
Fcgamma receptors (FcgammaRs) on mononuclear phagocytes trigger autoantibody and immune complex-induced diseases through coupling the self-reactive immunoglobulin G (IgG) response to innate effector pathways, such as phagocytosis, and the recruitment of inflammatory cells. FcRgamma-based activation is critical in the pathogenesis of these diseases, although the contribution of FcgammaR-mediated calcium signaling in autoimmune injury is unclear. Here we show that macrophages lacking the endoplasmic reticulum-resident calcium sensor, STIM1, cannot activate FcgammaR-induced Ca(2+) entry and phagocytosis. As a direct consequence, STIM1 deficiency results in resistance to experimental immune thrombocytopenia and anaphylaxis, autoimmune hemolytic anemia, and acute pneumonitis. These results establish STIM1 as a novel and essential component of FcgammaR activation and also indicate that inhibition of STIM1-dependent signaling might become a new strategy to prevent or treat IgG-dependent immunologic diseases.
Assuntos
Complexo Antígeno-Anticorpo/imunologia , Doenças Autoimunes/imunologia , Macrófagos/imunologia , Glicoproteínas de Membrana/imunologia , Fagocitose/imunologia , Receptores de IgG/imunologia , Animais , Complexo Antígeno-Anticorpo/genética , Autoanticorpos/genética , Autoanticorpos/imunologia , Doenças Autoimunes/genética , Doenças Autoimunes/patologia , Cálcio/imunologia , Canais de Cálcio , Feminino , Humanos , Imunoglobulina G/genética , Imunoglobulina G/imunologia , Inflamação/genética , Inflamação/imunologia , Inflamação/patologia , Macrófagos/patologia , Masculino , Glicoproteínas de Membrana/genética , Camundongos , Camundongos Knockout , Fagocitose/genética , Receptores de IgG/genética , Transdução de Sinais/genética , Transdução de Sinais/imunologia , Molécula 1 de Interação EstromalRESUMO
Fcgamma receptors (FcgammaR) and the C5a receptor (C5aR) are key effectors of the acute inflammatory response to IgG immune complexes (IC). Their coordinated activation is critical in IC-induced diseases, although the significance of combined signaling by these two different receptor classes in tissue injury is unclear. Here we used the mouse model of the passive reverse lung Arthus reaction to define their requirements for distinct phosphoinositide 3-kinase (PI3K) activities in vivo. We show that genetic deletion of class IB PI3Kgamma abrogates C5aR signaling that is crucial for FcgammaR-mediated activation of lung macrophages. Thus, in PI3Kgamma(-/-) mice, IgG IC-induced FcgammaR regulation, cytokine release, and neutrophil recruitment were blunted. Notably, however, C5a production occurred normally in PI3Kgamma(-/-) mice but was impaired in PI3Kdelta(-/-) mice. Consequently, class IA PI3Kdelta deficiency caused resistance to acute IC lung injury. These results demonstrate that PI3Kgamma and PI3Kdelta coordinate the inflammatory effects of C5aR and FcgammaR and define PI3Kdelta as a novel and essential element of FcgammaR signaling in the generation of C5a in IC disease.
Assuntos
Complexo Antígeno-Anticorpo/metabolismo , Reação de Arthus/enzimologia , Fosfatidilinositol 3-Quinases/metabolismo , Receptor da Anafilatoxina C5a/metabolismo , Receptores de IgG/metabolismo , Animais , Complexo Antígeno-Anticorpo/genética , Complexo Antígeno-Anticorpo/imunologia , Reação de Arthus/genética , Reação de Arthus/imunologia , Classe I de Fosfatidilinositol 3-Quinases , Classe Ib de Fosfatidilinositol 3-Quinase , Modelos Animais de Doenças , Imunoglobulina G/genética , Imunoglobulina G/imunologia , Imunoglobulina G/metabolismo , Inflamação/enzimologia , Inflamação/genética , Inflamação/imunologia , Isoenzimas/genética , Isoenzimas/imunologia , Isoenzimas/metabolismo , Camundongos , Camundongos Knockout , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositol 3-Quinases/imunologia , Receptor da Anafilatoxina C5a/genética , Receptor da Anafilatoxina C5a/imunologia , Receptores de IgG/genética , Receptores de IgG/imunologia , Transdução de Sinais/genética , Transdução de Sinais/imunologiaRESUMO
Complement and FcgammaR effector pathways are central triggers of immune inflammation; however, the exact mechanisms for their cooperation with effector cells and their nature remain elusive. In this study we show that in the lung Arthus reaction, the initial contact between immune complexes and alveolar macrophages (AM) results in plasma complement-independent C5a production that causes decreased levels of inhibitory FcgammaRIIB, increased levels of activating FcgammaRIII, and highly induced FcgammaR-mediated TNF-alpha and CXCR2 ligand production. Blockade of C5aR completely reversed such changes. Strikingly, studies of pertussis toxin inhibition show the essential role of G(i)-type G protein signaling in C5aR-mediated control of the regulatory FcgammaR system in vitro, and analysis of the various C5aR-, FcgammaR-, and G(i)-deficient mice verifies the importance of Galpha(i2)-associated C5aR and the FcgammaRIII-FcgammaRIIB receptor pair in lung inflammation in vivo. Moreover, adoptive transfer experiments of C5aR- and FcgammaRIII-positive cells into C5aR- and FcgammaRIII-deficient mice establish AM as responsible effector cells. AM lacking either C5aR or FcgammaRIII do not possess any such inducibility of immune complex disease, whereas reconstitution with FcgammaRIIB-negative AM results in an enhanced pathology. These data suggest that AM function as a cellular link of C5a production and C5aR activation that uses a Galpha(i2)-dependent signal for modulating the two opposing FcgammaR, FcgammaRIIB and FcgammaRIII, in the initiation of the inflammatory cascade in the lung Arthus reaction.
Assuntos
Reação de Arthus/imunologia , Reação de Arthus/patologia , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/metabolismo , Mediadores da Inflamação/metabolismo , Pulmão/patologia , Macrófagos Alveolares/imunologia , Proteínas de Membrana/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Receptores de Complemento/metabolismo , Receptores Fc/metabolismo , Animais , Reação de Arthus/metabolismo , Linhagem Celular , Complemento C5a/fisiologia , Subunidade alfa Gi2 de Proteína de Ligação ao GTP , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/fisiologia , Temperatura Alta , Imunoglobulina G/farmacologia , Mediadores da Inflamação/fisiologia , Pulmão/imunologia , Ativação de Macrófagos/imunologia , Macrófagos Alveolares/metabolismo , Proteínas de Membrana/biossíntese , Proteínas de Membrana/deficiência , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Proto-Oncogênicas/fisiologia , Receptor Cross-Talk/imunologia , Receptor da Anafilatoxina C5a , Receptores de Complemento/biossíntese , Receptores de Complemento/deficiência , Receptores de Complemento/genética , Receptores de IgG/deficiência , Receptores de IgG/genética , Receptores de IgG/metabolismo , Receptores de IgG/fisiologiaRESUMO
We constructed an oral live vaccine based on the attenuated aroA mutant Salmonella enterica serovar Typhimurium strain SL3261 expressing outer membrane proteins F and I (OprF-OprI) from Pseudomonas aeruginosa and investigated it in a mouse model. Strains with in vivo inducible protein expression with the PpacC promoter showed good infection rates and immunogenicity but failed to engender detectable antibodies in the lung. However, a systemic booster vaccination following an oral primary immunization yielded high immunoglobulin A (IgA) and IgG antibody levels in both upper and lower airways superior to conventional systemic or mucosal booster vaccination alone. In addition, the proportion of IgG1 and IgG2a antibodies suggested that the systemic booster does not alter the more TH1-like type of response induced by the oral Salmonella primary vaccination. We conclude that an oral primary systemic booster vaccination strategy with an appropriate mucosal vector may be advantageous in diseases with the risk of P. aeruginosa airway infection, such as cystic fibrosis.
Assuntos
Proteínas de Bactérias/imunologia , Vacinas Bacterianas/imunologia , Lipoproteínas/imunologia , Porinas/imunologia , Pseudomonas aeruginosa/imunologia , Mucosa Respiratória/imunologia , Salmonella typhimurium/genética , Administração Oral , Animais , Anticorpos Antibacterianos/análise , Anticorpos Antibacterianos/sangue , Proteínas de Bactérias/administração & dosagem , Proteínas de Bactérias/genética , Vacinas Bacterianas/genética , Humanos , Imunidade nas Mucosas , Lipoproteínas/administração & dosagem , Lipoproteínas/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Porinas/administração & dosagem , Porinas/genética , Infecções por Pseudomonas/prevenção & controle , Proteínas Recombinantes de Fusão/imunologia , Proteínas Recombinantes de Fusão/metabolismo , Salmonella typhimurium/imunologia , Vacinação , Vacinas Atenuadas/genética , Vacinas Atenuadas/imunologia , Vacinas Sintéticas/imunologiaRESUMO
Immune complex (IC)-induced inflammation is integral to the pathogenesis of several autoimmune diseases. ICs activate the complement system and interact with IgG FcgammaR. In this study, we demonstrate that activation of the complement system, specifically generation of C5a, initiates the neutrophilic inflammation in IC peritonitis. We show that ablation of C5a receptor signaling abrogates neutrophil recruitment in wild-type mice and prevents the enhancement of neutrophil migration seen in FcgammaRIIB(-/-) mice, suggesting that C5aR signaling is the crucial initial event upstream of FcgammaR signaling. We also provide evidence that C5a initiates the inflammatory cascade both directly, through C5aR-mediated effector functions on infiltrating and resident peritoneal cells, and indirectly, through shifting the balance between activating and inhibitory FcgammaRs on resident cells toward an inflammatory phenotype. We conclude that complement activation and C5a generation are prerequisites for IC-induced inflammation through activating FcgammaR, which amplifies complement-induced inflammation in autoimmunity.
Assuntos
Complemento C5a/metabolismo , Doenças do Complexo Imune/metabolismo , Inflamação/metabolismo , Peritonite/metabolismo , Animais , Movimento Celular/imunologia , Quimiocinas CXC/imunologia , Quimiocinas CXC/metabolismo , Feminino , Doenças do Complexo Imune/imunologia , Inflamação/imunologia , Macrófagos/imunologia , Macrófagos/metabolismo , Camundongos , Neutrófilos/imunologia , Peritonite/imunologia , Receptor da Anafilatoxina C5a/imunologia , Receptor da Anafilatoxina C5a/metabolismo , Receptores de IgG/imunologia , Receptores de IgG/metabolismo , Transdução de Sinais/imunologia , Transdução de Sinais/fisiologiaRESUMO
IgG Fc receptors (FcgammaRs, especially FcgammaRIII) and complement (in particular, C5a anaphylatoxin) are critical effectors of the acute inflammatory response to immune complexes (ICs). However, it is unknown whether and how these two key components can interact with each other in vivo. We use here a mouse model of the acute pulmonary IC hypersensitivity reaction to analyze their potential interaction. FcgammaRIII and C5aR are coexpressed on alveolar macrophages (AMs), and both FcgammaRIII and C5aR mutant mice display impaired immune responses. We find that recombinant human C5a (rhC5a) can control inverse expression of various FcgammaRs, and costimulation of ICs with rhC5a results in strong enhancement of FcgammaRIII-triggered cellular activation in vitro and in vivo. Moreover, we show here that early IC-induced bioactive C5a, and its interaction with C5aR, causes induction of activating FcgammaRIII and suppression of inhibitory FcgammaRII on AMs that appears crucial for efficient cytokine production and neutrophil recruitment in lung pathology. Therefore, C5a, which is a potent chemoattractant, has a broader critical function in regulating the inhibitory/activating FcgammaRII/III receptor pair to connect complement and FcgammaR effector pathways in immune inflammation.
Assuntos
Complexo Antígeno-Anticorpo/imunologia , Complemento C5a/imunologia , Doenças do Complexo Imune/imunologia , Pneumopatias/imunologia , Receptores de IgG/imunologia , Animais , Complexo Antígeno-Anticorpo/metabolismo , Antígenos CD/metabolismo , Células da Medula Óssea/citologia , Células da Medula Óssea/metabolismo , Líquido da Lavagem Broncoalveolar/química , Líquido da Lavagem Broncoalveolar/citologia , Separação Celular , Células Cultivadas , Quimiotaxia/fisiologia , Complemento C5a/metabolismo , Modelos Animais de Doenças , Citometria de Fluxo , Humanos , Doenças do Complexo Imune/metabolismo , Pneumopatias/metabolismo , Macrófagos Alveolares/citologia , Macrófagos Alveolares/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ovalbumina/metabolismo , Receptor da Anafilatoxina C5a , Receptores de Complemento/metabolismo , Receptores de IgG/metabolismo , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/metabolismoRESUMO
We examined the capacity of mouse glomerular mesangial cells (MC) to express and function through two different low affinity FcgammaRs, the activating FcgammaRIII and the inhibitory FcgammaRII. Immunohistochemistry identified FcgammaRII as the prominent FcgammaR in the kidney, and low levels of FcgammaRIIb2-specific mRNA were also detected in primary cultures of growth-arrested MC. Activation by tumor necrosis factor-alpha/interleukin-1beta induced substantial FcgammaRII expression in proliferating MC. Importantly, however, stimulation with interferon-gamma (IFN-gamma)/lipopolysaccharide or IFN-gamma alone resulted in a complete down-regulation of FcgammaRII, which was accompanied by a strong increase in FcRgamma chain mRNA and a surface appearance of FcgammaRIII. Activating FcgammaRIII triggered mRNA synthesis for monocyte chemoattractant protein-1 (MCP-1), MCP-5, cytokine-induced neutrophil chemoattractant, and RANTES, whereas FcgammaRIII-deficient MC failed to respond to immune complex (IC) activation as shown by impaired production of MCP-1 mRNA/protein. In a passive model of acute anti-glomerular basement membrane (GBM) nephritis, induction of FcgammaRIII and suppression of FcgammaRII occurred in kidney tissues. Blockade of FcgammaRII, when induced selectively in the kidney, resulted in enhanced inflammation. Taken together, our results define a novel regulatory pathway with opposite regulation of FcgammaRII (suppressed) and FcgammaRIII (induced) by IFN-gamma on MCs in vitro and anti-GBM IgG in vivo. Herein is provided the first evidence that glomerular FcgammaRII plays an important immunoregulatory role in the initiation of IC glomerulonephritis.