RESUMO
BACKGROUND: Mixed connective tissue disease (MCTD) is a rare and complex autoimmune disease that presents mixed features with other connective tissue diseases, such as systemic lupus erythematosus, systemic sclerosis, and myositis. It is characterized by high levels of anti-U1 small nuclear ribonucleoprotein 70k autoantibodies and a high incidence of life-threatening pulmonary involvement. The pathophysiology of MCTD is not well understood, and no specific treatment is yet available for the patients. Basophils and IgE play a role in the development of systemic lupus erythematosus and thus represent new therapeutic targets for systemic lupus erythematosus and other diseases involving basophils and IgE in their pathogenesis. OBJECTIVE: We sought to investigate the role of basophils and IgE in the pathophysiology of MCTD. METHODS: Basophil activation status and the presence of autoreactive IgE were assessed in peripheral blood of a cohort of patients with MCTD and in an MCTD-like mouse model. Basophil depletion and IgE-deficient animals were used to investigate the contribution of basophils and IgE in the lung pathology development of this mouse model. RESULTS: Patients with MCTD have a peripheral basopenia and activated blood basophils overexpressing C-C chemokine receptor 3. Autoreactive IgE raised against the main MCTD autoantigen U1 small nuclear ribonucleoprotein 70k were found in nearly 80% of the patients from the cohort. Basophil activation and IgE anti-U1 small nuclear ribonucleoprotein 70k were also observed in the MCTD-like mouse model along with basophil accumulation in lymph nodes and lungs. Basophil depletion dampened lung pathology, and IgE deficiency prevented its development. CONCLUSIONS: Basophils and IgE contribute to MCTD pathophysiology and represent new candidate therapeutic targets for patients with MCTD.
Assuntos
Autoanticorpos/imunologia , Basófilos/imunologia , Imunoglobulina E/imunologia , Doença Mista do Tecido Conjuntivo/imunologia , Ribonucleoproteína Nuclear Pequena U1/imunologia , Adulto , Animais , Feminino , Humanos , Pulmão/imunologia , Pulmão/patologia , Linfonodos/imunologia , Masculino , Camundongos Transgênicos , Pessoa de Meia-Idade , Doença Mista do Tecido Conjuntivo/patologiaRESUMO
Here we investigated the role of murine mast cell protease 4 (MCPT4), the functional counterpart of human mast cell chymase, in an experimental model of renal ischemia reperfusion injury, a major cause of acute kidney injury. MCPT4-deficient mice had worsened kidney function compared to wildtype mice. MCPT4 absence exacerbated pathologic neutrophil infiltration in the kidney and increased kidney myeloperoxidase expression, cell death and necrosis. In kidneys with ischemia reperfusion injury, when compared to wildtype mice, MCPT4-deficient mice showed increased surface expression of adhesion molecules necessary for leukocyte extravasation including neutrophil CD162 and endothelial cell CD54. In vitro, human chymase mediated the cleavage of neutrophil expressed CD162 and also CD54, P- and E-Selectin expressed on human glomerular endothelial cells. MCPT4 also dampened systemic neutrophil activation after renal ischemia reperfusion injury as neutrophils expressed more CD11b integrin and produced more reactive oxygen species in MCPT4-deficient mice. Accordingly, after renal injury, neutrophil migration to an inflammatory site distal from the kidney was increased in MCPT4-deficient versus wildtype mice. Thus, contrary to the described overall aggravating role of mast cells, one granule-released mediator, the MCPT4 chymase, exhibits a potent anti-inflammatory function in renal ischemia reperfusion injury by controlling neutrophil extravasation and activation thereby limiting associated damage.
Assuntos
Injúria Renal Aguda , Quimases , Mastócitos/enzimologia , Traumatismo por Reperfusão , Injúria Renal Aguda/prevenção & controle , Animais , Células Endoteliais , Rim , Camundongos , Camundongos Endogâmicos C57BL , Neutrófilos , Traumatismo por Reperfusão/prevenção & controleRESUMO
A sizable part (~2%) of the human genome encodes for proteases. They are involved in many physiological processes, such as development, reproduction and inflammation, but also play a role in pathology. Mast cells (MC) contain a variety of MC specific proteases, the expression of which may differ between various MC subtypes. Amongst these proteases, chymase represents up to 25% of the total proteins in the MC and is released from cytoplasmic granules upon activation. Once secreted, it cleaves the targets in the local tissue environment, but may also act in lymph nodes infiltrated by MC, or systemically, when reaching the circulation during an inflammatory response. MC have been recognized as important components in the development of kidney disease. Based on this observation, MC chymase has gained interest following the discovery that it contributes to the angiotensin-converting enzyme's independent generation of angiotensin II, an important inflammatory mediator in the development of kidney disease. Hence, progress regarding its role has been made based on studies using inhibitors but also on mice deficient in MC protease 4 (mMCP-4), the functional murine counterpart of human chymase. In this review, we discuss the role and actions of chymase in kidney disease. While initially believed to contribute to pathogenesis, the accumulated data favor a more subtle view, indicating that chymase may also have beneficial actions.
Assuntos
Quimases/metabolismo , Suscetibilidade a Doenças , Nefropatias/etiologia , Nefropatias/metabolismo , Mastócitos/enzimologia , Mastócitos/imunologia , Angiotensina II/metabolismo , Animais , Biomarcadores , Quimases/antagonistas & inibidores , Gerenciamento Clínico , Humanos , Nefropatias/tratamento farmacológico , Nefropatias/patologia , Mastócitos/efeitos dos fármacos , Terapia de Alvo Molecular , Nefrite/etiologia , Nefrite/metabolismo , Nefrite/patologia , Inibidores de Serina Proteinase/farmacologiaRESUMO
Renal transplants remain a medical challenge, because the parameters governing allograft outcome are incompletely identified. Here, we investigated the role of serum iron in the sterile inflammation that follows kidney ischemia-reperfusion injury. In a retrospective cohort study of renal allograft recipients (n=169), increased baseline levels of serum ferritin reliably predicted a positive outcome for allografts, particularly in elderly patients. In mice, systemic iron overload protected against renal ischemia-reperfusion injury-associated sterile inflammation. Furthermore, chronic iron injection in mice prevented macrophage recruitment after inflammatory stimuli. Macrophages cultured in high-iron conditions had reduced responses to Toll-like receptor-2, -3, and -4 agonists, which associated with decreased reactive oxygen species production, increased nuclear localization of the NRF2 transcription factor, increased expression of the NRF2-related antioxidant response genes, and limited NF-κB and proinflammatory signaling. In macrophage-depleted animals, the infusion of macrophages cultured in high-iron conditions did not reconstitute AKI after ischemia-reperfusion, whereas macrophages cultured in physiologic iron conditions did. These findings identify serum iron as a critical protective factor in renal allograft outcome. Increasing serum iron levels in patients may thus improve prognosis of renal transplants.
Assuntos
Ferro/sangue , Rim/patologia , Traumatismo por Reperfusão/prevenção & controle , Adulto , Aloenxertos , Animais , Antioxidantes/metabolismo , Feminino , Ferritinas/sangue , Taxa de Filtração Glomerular , Humanos , Inflamação , Ferro/química , Rim/metabolismo , Transplante de Rim , Macrófagos/citologia , Macrófagos/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Monócitos/citologia , Fator 2 Relacionado a NF-E2/metabolismo , Peritonite/metabolismo , Prognóstico , Espécies Reativas de Oxigênio/metabolismo , Traumatismo por Reperfusão/metabolismo , Transdução de SinaisRESUMO
Proteinase 3 (PR3), the autoantigen in granulomatosis with polyangiitis, is expressed at the plasma membrane of resting neutrophils, and this membrane expression increases during both activation and apoptosis. Using surface plasmon resonance and protein-lipid overlay assays, this study demonstrates that PR3 is a phosphatidylserine-binding protein and this interaction is dependent on the hydrophobic patch responsible for membrane anchorage. Molecular simulations suggest that PR3 interacts with phosphatidylserine via a small number of amino acids, which engage in long lasting interactions with the lipid heads. As phosphatidylserine is a major component of microvesicles (MVs), this study also examined the consequences of this interaction on MV production and function. PR3-expressing cells produced significantly fewer MVs during both activation and apoptosis, and this reduction was dependent on the ability of PR3 to associate with the membrane as mutating the hydrophobic patch restored MV production. Functionally, activation-evoked MVs from PR3-expressing cells induced a significantly larger respiratory burst in human neutrophils compared with control MVs. Conversely, MVs generated during apoptosis inhibited the basal respiratory burst in human neutrophils, and those generated from PR3-expressing cells hampered this inhibition. Given that membrane expression of PR3 is increased in patients with granulomatosis with polyangiitis, MVs generated from neutrophils expressing membrane PR3 may potentiate oxidative damage of endothelial cells and promote the systemic inflammation observed in this disease.
Assuntos
Micropartículas Derivadas de Células/metabolismo , Mieloblastina/metabolismo , Fosfatidilserinas/metabolismo , Animais , Apoptose , Linhagem Celular , Granulomatose com Poliangiite/enzimologia , Granulomatose com Poliangiite/etiologia , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Simulação de Acoplamento Molecular , Mieloblastina/química , Neutrófilos/metabolismo , Proteínas de Transferência de Fosfolipídeos/metabolismo , Ratos , Explosão RespiratóriaRESUMO
The mechanism for anti-inflammatory action of intravenous immunoglobulin (IVIg) in the treatment of autoimmune and inflammatory diseases involves IgG Fc receptors (FcγR). Although the inhibitory FcγRIIB plays an important role in IVIg action, FcγRIIIA has recently been identified as another major anti-inflammatory actor. Interaction of FcγRIIIA with uncomplexed IgG1 or IVIg, or with bivalent anti-FcγRIII F(ab')2 dampened calcium responses, ROS production, endocytosis and phagocytosis, induced by heterologous activating receptors. This inhibitory action required the inhibitory configuration of the ITAM motif (ITAMi) present within the FcγRIII-associated FcRγ subunit. This allowed SHP-1 recruitment and formation of intracellular inhibisome clusters containing FcγRIII and the targeted activating receptor. Therefore, IVIg functionally interact with FcγRIIIA inducing ITAMi signaling which can prevent development of autoimmune and inflammatory disorders independently of FcγRIIB. This new mechanism of action for IVIg reveals a therapeutic potential for FcγRIIIA targeting in inflammatory diseases.
Assuntos
Doenças Autoimunes/terapia , Imunoglobulinas Intravenosas/imunologia , Imunoterapia/métodos , Inflamação/terapia , Receptores de IgG/metabolismo , Motivos de Aminoácidos/genética , Animais , Doenças Autoimunes/imunologia , Sinalização do Cálcio , Humanos , Imunoglobulinas Intravenosas/uso terapêutico , Inflamação/imunologia , Complexos Multiproteicos/metabolismo , Estresse Oxidativo , Fagocitose , Ligação Proteica , Proteína Tirosina Fosfatase não Receptora Tipo 6/metabolismo , Receptores de IgG/imunologia , Transdução de SinaisRESUMO
Intravenous immunoglobulin (IVIg) has been used in the treatment of several autoimmune and inflammatory diseases. However, its mechanism of action remains incompletely understood. Here, we investigated the possibility that IVIg induces its anti-inflammatory effects through activating Fcγ receptors bearing an immunoreceptor tyrosine-based activation motif (ITAM) in the FcRγ signaling adaptor. Recently, the concept of inhibitory ITAM (ITAMi) has emerged as a new means to negatively control the immune response. We found that interaction of FcRγ-associated mouse or human FcγRIII with uncomplexed IgG1 or IVIg, or with bivalent anti-FcγRIII F(ab')(2) reduced calcium responses, reactive oxygen species production, endocytosis, and phagocytosis, induced by heterologous activating receptors on monocyte/macrophages and FcγRIII(+) transfectants. Inhibition required the ITAMi configuration of the FcγRIII-associated FcRγ subunit and SHP-1 recruitment involving formation of intracellular "inhibisome" clusters containing FcγRIII, and the targeted heterologous activating receptor. IVIg as well as anti-FcγRIII treatments controlled the development of nonimmune mediated inflammation in vivo independently of FcγRIIB. These results demonstrate that circulating immunoglobulins (Ig)Gs are not functionally inert but act through continuous interaction with FcγRIII-inducing ITAMi signaling to maintain immune homeostasis. These data support a new mechanism of action for IVIg and demonstrate the therapeutic potential of FcγRIIIA targeting in inflammation.
Assuntos
Antígenos de Superfície/imunologia , Imunoglobulina G/farmacologia , Imunoglobulinas Intravenosas/farmacologia , Inflamação/imunologia , Receptores de IgG/fisiologia , Motivos de Aminoácidos/efeitos dos fármacos , Motivos de Aminoácidos/imunologia , Animais , Antígenos de Superfície/química , Antígenos de Superfície/efeitos dos fármacos , Células Cultivadas , Regulação para Baixo/efeitos dos fármacos , Regulação para Baixo/imunologia , Humanos , Inflamação/metabolismo , Inflamação/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/imunologia , Tirosina/imunologiaRESUMO
A favorable outcome following acute bacterial infection depends on the ability of phagocytic cells to be recruited and properly activated within injured tissues. Calcium (Ca(2+)) is a ubiquitous second messenger implicated in the functions of many cells, but the mechanisms involved in the regulation of Ca(2+) mobilization in hematopoietic cells are largely unknown. The monovalent cation channel transient receptor potential melastatin (TRPM) 4 is involved in the control of Ca(2+) signaling in some hematopoietic cell types, but the role of this channel in phagocytes and its relevance in the control of inflammation remain unexplored. In this study, we report that the ablation of the Trpm4 gene dramatically increased mouse mortality in a model of sepsis induced by cecal ligation and puncture. The lack of the TRPM4 channel affected macrophage population within bacteria-infected peritoneal cavities and increased the systemic level of Ly6C(+) monocytes and proinflammatory cytokine production. Impaired Ca(2+) mobilization in Trpm4(-/-) macrophages downregulated the AKT signaling pathway and the subsequent phagocytic activity, resulting in bacterial overgrowth and translocation to the bloodstream. In contrast, no alteration in the distribution, function, or Ca(2+) mobilization of Trpm4(-/-) neutrophils was observed, indicating that the mechanism controlling Ca(2+) signaling differs among phagocytes. Our results thus show that the tight control of Ca(2+) influx by the TRPM4 channel is critical for the proper functioning of monocytes/macrophages and the efficiency of the subsequent response to infection.
Assuntos
Macrófagos/imunologia , Macrófagos/patologia , Monócitos/imunologia , Monócitos/patologia , Neutrófilos , Sepse/imunologia , Canais de Cátion TRPM/fisiologia , Animais , Células da Medula Óssea/imunologia , Células da Medula Óssea/metabolismo , Células da Medula Óssea/patologia , Sobrevivência Celular/genética , Sobrevivência Celular/imunologia , Células Cultivadas , Humanos , Macrófagos/metabolismo , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Monócitos/metabolismo , Neutrófilos/imunologia , Neutrófilos/metabolismo , Neutrófilos/patologia , Peritonite/imunologia , Peritonite/metabolismo , Peritonite/patologia , Sepse/metabolismo , Sepse/patologia , Canais de Cátion TRPM/biossíntese , Canais de Cátion TRPM/deficiênciaRESUMO
Sepsis, a leading cause of death worldwide, involves proinflammatory responses and inefficient bacterial clearance. Phagocytic cells play a crucial part in the prevention of sepsis by clearing bacteria through host innate receptors. Here we show that the FcRgamma adaptor, an immunoreceptor tyrosine-based activation motif (ITAM)-bearing signal transduction subunit of the Fc receptor family, has a deleterious effect on sepsis. FcRgamma(-/-) mice show increased survival during peritonitis, owing to markedly increased E. coli phagocytosis and killing and to lower production of the proinflammatory cytokine tumor necrosis factor (TNF)-alpha. The FcRgamma-associated receptor that inhibits E. coli phagocytosis is FcgammaRIII (also called CD16), and its absence protects mice from sepsis. FcgammaRIII binds E. coli, and this interaction induces FcRgamma phosphorylation, recruitment of the tyrosine phosphatase SHP-1 and phosphatidylinositide-3 kinase (PI3K) dephosphorylation. Decreased PI3K activity inhibits E. coli phagocytosis and increases TNF-alpha production through Toll-like receptor 4. We identified the phagocytic receptor negatively regulated by FcRgamma on macrophages as the class A scavenger receptor MARCO. E. coli-FcgammaRIII interaction induces the recruitment of SHP-1 to MARCO, thereby inhibiting E. coli phagocytosis. Thus, by binding FcgammaRIII, E. coli triggers an inhibitory FcRgamma pathway that both impairs MARCO-mediated bacterial clearance and activates TNF-alpha secretion.
Assuntos
Infecções por Escherichia coli/imunologia , Mediadores da Inflamação/fisiologia , Fagocitose/imunologia , Receptores de IgG/fisiologia , Sepse/imunologia , Transdução de Sinais/imunologia , Animais , Células da Medula Óssea/imunologia , Células da Medula Óssea/metabolismo , Células da Medula Óssea/patologia , Linhagem Celular , Células Cultivadas , Infecções por Escherichia coli/metabolismo , Infecções por Escherichia coli/microbiologia , Escherichia coli K12/imunologia , Mediadores da Inflamação/metabolismo , Macrófagos/imunologia , Macrófagos/metabolismo , Macrófagos/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Proteína Tirosina Fosfatase não Receptora Tipo 6/fisiologia , Receptores de IgG/deficiência , Receptores de IgG/genética , Receptores Imunológicos/antagonistas & inibidores , Receptores Imunológicos/fisiologia , Sepse/metabolismo , Sepse/microbiologia , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by anti-nuclear autoantibodies whose production is promoted by autoreactive T follicular helper (TFH) cells. During SLE pathogenesis, basophils accumulate in secondary lymphoid organs (SLO), amplify autoantibody production and disease progression through mechanisms that remain to be defined. Here, we provide evidence for a direct functional relationship between TFH cells and basophils during lupus pathogenesis, both in humans and mice. PD-L1 upregulation on basophils and IL-4 production are associated with TFH and TFH2 cell expansions and with disease activity. Pathogenic TFH cell accumulation, maintenance, and function in SLO were dependent on PD-L1 and IL-4 in basophils, which induced a transcriptional program allowing TFH2 cell differentiation and function. Our study establishes a direct mechanistic link between basophils and TFH cells in SLE that promotes autoantibody production and lupus nephritis.
Assuntos
Antígeno B7-H1 , Basófilos , Interleucina-4 , Lúpus Eritematoso Sistêmico , Células T Auxiliares Foliculares , Adulto , Animais , Feminino , Humanos , Masculino , Camundongos , Pessoa de Meia-Idade , Autoanticorpos/imunologia , Antígeno B7-H1/metabolismo , Antígeno B7-H1/genética , Basófilos/imunologia , Basófilos/metabolismo , Diferenciação Celular/imunologia , Interleucina-4/metabolismo , Interleucina-4/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Lúpus Eritematoso Sistêmico/metabolismo , Lúpus Eritematoso Sistêmico/patologia , Nefrite Lúpica/imunologia , Nefrite Lúpica/patologia , Nefrite Lúpica/metabolismo , Camundongos Endogâmicos C57BL , Células T Auxiliares Foliculares/imunologia , Células T Auxiliares Foliculares/metabolismo , Linfócitos T Auxiliares-Indutores/imunologia , Linfócitos T Auxiliares-Indutores/metabolismoRESUMO
Immune homeostasis is regulated by a finely tuned network of positive-negative regulatory mechanisms that guarantees proper surveillance avoiding hyperactivity that would lead to autoimmunity and inflammatory diseases. Immune responses involve the activation of immunoreceptors that contain tyrosine-based activation motifs (ITAMs). One arm of control involves immunoreceptor tyrosine-based inhibitory motif (ITIM)-bearing receptors, which upon co-aggregation initiate an inhibitory signal through recruitment of signal-aborting phosphatases. Recently, a new immunoregulatory function has been ascribed to ITAMs, which represent in fact dual function modules that, under specific configurations termed inhibitory ITAM (ITAMi), can propagate inhibitory signals. One paradigm is the immunoglobulin A (IgA) Fc receptor (FcalphaRI), which, upon interaction with IgA monomers in the absence of antigen, initiates a powerful inhibitory signal involving Src homology 2 domain-containing phosphatase 1 (SHP-1) recruitment that suppresses cell activation launched by a whole variety of heterologous receptors without co-aggregation. This explains the long known function of IgA as an anti-inflammatory isotype. The importance of this control mechanism in immune homeostasis is underlined by the high incidence of autoimmune and allergic diseases in IgA-deficient patients. ITAMi is now described for an increasing number of immunoreceptors with multiple roles in immunity. ITAMi signaling is also exploited by Escherichia coli to achieve immune evasion during sepsis. Here, we review our current understanding of ITAMi regulatory mechanisms in immune responses and discuss its role in immune homeostasis.
Assuntos
Antígenos CD/metabolismo , Doenças Autoimunes/imunologia , Hipersensibilidade/imunologia , Imunidade , Imunoglobulina A/metabolismo , Domínios e Motivos de Interação entre Proteínas/imunologia , Receptores Fc/metabolismo , Animais , Antígenos CD/imunologia , Doenças Autoimunes/terapia , Retroalimentação Fisiológica , Humanos , Hipersensibilidade/terapia , Evasão da Resposta Imune/fisiologia , Imunoglobulina A/imunologia , Imunoglobulinas Intravenosas/uso terapêutico , Receptores Fc/imunologia , Transdução de Sinais/imunologia , Tirosina/imunologia , Tirosina/metabolismoRESUMO
IgA nephropathy (IgAN), the most common primary glomerulonephritis worldwide, has significant morbidity and mortality as 20-40% of patients progress to end-stage renal disease within 20 years of onset. In order to gain insight into the molecular mechanisms involved in the progression of IgAN, we systematically evaluated renal biopsies from such patients. This showed that the MAPK/ERK signaling pathway was activated in the mesangium of patients presenting with over 1 g/day proteinuria and elevated blood pressure, but absent in biopsy specimens of patients with IgAN and modest proteinuria (<1 g/day). ERK activation was not associated with elevated galactose-deficient IgA1 or IgG specific for galactose-deficient IgA1 in the serum. In human mesangial cells in vitro, ERK activation through mesangial IgA1 receptor (CD71) controlled pro-inflammatory cytokine secretion and was induced by large-molecular-mass IgA1-containing circulating immune complexes purified from patient sera. Moreover, IgA1-dependent ERK activation required renin-angiotensin system as its blockade was efficient in reducing proteinuria in those patients exhibiting substantial mesangial activation of ERK. Thus, ERK activation alters mesangial cell-podocyte crosstalk, leading to renal dysfunction in IgAN. Assessment of MAPK/ERK activation in diagnostic renal biopsies may predict the therapeutic efficacy of renin-angiotensin system blockers in IgAN.
Assuntos
Comunicação Celular , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Glomerulonefrite por IGA/imunologia , Imunoglobulina A/metabolismo , Sistema de Sinalização das MAP Quinases , Células Mesangiais/imunologia , Podócitos/imunologia , Adulto , Idoso , Angiotensina II/metabolismo , Bloqueadores do Receptor Tipo 1 de Angiotensina II/farmacologia , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Complexo Antígeno-Anticorpo , Antígenos CD/metabolismo , Biópsia , Pressão Sanguínea , Cálcio/metabolismo , Comunicação Celular/efeitos dos fármacos , Proliferação de Células , Células Cultivadas , Ativação Enzimática , Feminino , Glomerulonefrite por IGA/enzimologia , Glomerulonefrite por IGA/patologia , Glomerulonefrite por IGA/fisiopatologia , Humanos , Mediadores da Inflamação/metabolismo , Interleucina-6/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Masculino , Células Mesangiais/efeitos dos fármacos , Células Mesangiais/enzimologia , Células Mesangiais/patologia , Pessoa de Meia-Idade , Fosfatidilinositol 3-Quinase/metabolismo , Fosforilação , Podócitos/efeitos dos fármacos , Podócitos/enzimologia , Podócitos/patologia , Proteinúria/enzimologia , Proteinúria/imunologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores da Transferrina/metabolismo , Sistema Renina-Angiotensina , Serina-Treonina Quinases TOR/metabolismo , Fatores de Tempo , Adulto JovemRESUMO
Tissue-specific mouse models are essential tools to decipher the role of each cell compartment and/or their expressed genes in the pathophysiology of diseases. Here, we describe a new knock-in mouse model allowing expression of both the fluorescent protein tdTomato and the CRE recombinase selectively in the basophil compartment under the control of the Mcpt8 gene. These "CT-M8" mice did not show any abnormalities in their peripheral distribution of major immune cell populations nor their basophil function. CT-M8 mice allowed the identification of basophils by immunofluorescence and flow cytometry and basophil-specific Cre-mediated floxed gene deletion. Breeding of our CT-M8 mice with the ROSA26flox-stop-DTA mice led to the generation of basophil-deficient mice with no detectable abnormalities in other cell compartments. These mice were then used to document basophil involvement in systemic lupus erythematosus (SLE) pathophysiology since we previously reported by transient depletion of these cells during the course of an ongoing disease that they support and amplify autoantibody production in two distinct lupus-like mouse models (Lyn-/- and pristane-induced). Here, constitutive basophil deficiency prevented pristane-induced lupus-like disease development by limiting autoantibody titers and renal damages. Therefore, basophils have a nonredundant role in pristane-induced lupus-like disease and are involved in both its induction and amplification. This CT-M8 new mouse model will allow us to finely decipher the role of basophils and their expressed genes in health and disease.
Assuntos
Basófilos , Lúpus Eritematoso Sistêmico , Animais , Modelos Animais de Doenças , Contagem de Leucócitos , Lúpus Eritematoso Sistêmico/genética , Camundongos , Tomografia Computadorizada por Raios XRESUMO
The function of intracellular trafficking in immune-complex triggered inflammation remains poorly understood. Here, we investigated the role of Insulin-Regulated Amino Peptidase (IRAP)-positive endosomal compartments in Fc receptor (FcR)-induced inflammation. Less severe FcγR-triggered arthritis, active systemic anaphylaxis and FcεRI-triggered passive systemic anaphylaxis were observed in IRAP-deficient versus wild-type mice. In mast cells FcεRI stimulation induced rapid plasma membrane recruitment of IRAP-positive endosomes. IRAP-deficient cells exhibited reduced secretory responses, calcium signaling and activating SykY519/520 phosphorylation albeit receptor tyrosine phosphorylation on ß and γ subunits was not different. By contrast, in the absence of IRAP, SHP1-inactivating phosphorylation on Ser591 that controls Syk activity was decreased. Ex-vivo cell profiling after FcγR-triggered anaphylaxis confirmed decreased phosphorylation of both SykY519/520 and SHP-1S591 in IRAP-deficient neutrophils and monocytes. Thus, IRAP-positive endosomal compartments, in promoting inhibition of SHP-1 during FcR signaling, control the extent of phosphorylation events at the plasma membrane and contribute to setting the intensity of immune-complex triggered inflammatory diseases.
Assuntos
Anafilaxia , Insulina , Animais , Camundongos , Insulina/farmacologia , Aminopeptidases/metabolismo , Cistinil Aminopeptidase , Receptores Fc , Receptores de IgG/genética , Receptores de IgE , Complexo Antígeno-Anticorpo , InflamaçãoRESUMO
BACKGROUND: Erythrocytosis is a hematological disorder usually related to hematopoietic stem cell somatic mutations. However, unexplained erythrocytosis remains frequent. In this study, we evaluated the involvement of IgA1, a regulator of erythropoiesis also implicated in IgA nephropathy (IgAN) pathophysiology, in unexplained polycythemia/erythrocytosis (PE) of IgAN patients. METHODS: IgAN-PE patients' serum was collected, analyzed and used to study IgA1 effect on proliferation and differentiation of erythroid progenitors. Hematological parameters of transgenic mice for human alpha1 heavy chain were studied. Multicentric observational cohorts of chronic kidney disease (CKD) patients, including both native kidney diseases and renal transplants, were studied to analyze patient hemoglobin levels. FINDINGS: We retrospectively identified 6 patients with IgAN and unexplained PE. In large CKD cohorts, IgAN was associated with PE in 3.5% of patients (p<0.001 compared to other nephropathies). IgAN was an independent factor associated with higher hemoglobin levels (13.1g/dL vs 12.2 g/dL, p=0.01). During post-transplant anemia, anemia recovery was faster in IgAN patients. Elevated polymeric/monomeric IgA1 ratio as well as high Gd-IgA1 rate were observed in circulating IgA1 of the 6 IgAN-PE patients as compared with control or IgAN patients without PE. IgA1 from these patients increased the sensitivity of erythroid progenitors to Epo. In mice, we also observed an elevation of hematocrit in alpha1 knock-in mice compared to wild type controls. INTERPRETATION: These data identify a new etiology of erythrocytosis and demonstrate the role of pIgA1 in human erythropoiesis. This syndrome of IgA-related erythrocytosis should be investigated in case of unexplained erythrocytosis and renal disease. FUNDING: This work was supported by INSERM (French national institute for health and medical research), Labex GRex and Imagine Institute (Paris, France).
Assuntos
Glomerulonefrite por IGA , Policitemia , Animais , Biomarcadores , Galactose , Glomerulonefrite por IGA/complicações , Glomerulonefrite por IGA/genética , Humanos , Imunoglobulina A , Camundongos , Policitemia/complicações , Policitemia/genética , Estudos RetrospectivosRESUMO
Vitamin D (VD) is a known differentiating agent, but the role of VD receptor (VDR) is still incompletely described in acute myeloid leukemia (AML), whose treatment is based mostly on antimitotic chemotherapy. Here, we present an unexpected role of VDR in normal hematopoiesis and in leukemogenesis. Limited VDR expression is associated with impaired myeloid progenitor differentiation and is a new prognostic factor in AML. In mice, the lack of Vdr results in increased numbers of hematopoietic and leukemia stem cells and quiescent hematopoietic stem cells. In addition, malignant transformation of Vdr-/- cells results in myeloid differentiation block and increases self-renewal. Vdr promoter is methylated in AML as in CD34+ cells, and demethylating agents induce VDR expression. Association of VDR agonists with hypomethylating agents promotes leukemia stem cell exhaustion and decreases tumor burden in AML mouse models. Thus, Vdr functions as a regulator of stem cell homeostasis and leukemic propagation.
Assuntos
Medula Óssea/patologia , Leucemia Mieloide Aguda/metabolismo , Leucemia Mieloide Aguda/patologia , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Receptores de Calcitriol/metabolismo , Animais , Apoptose/efeitos dos fármacos , Azacitidina/farmacologia , Medula Óssea/efeitos dos fármacos , Contagem de Células , Ciclo Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular Tumoral , DNA (Citosina-5-)-Metiltransferases/antagonistas & inibidores , DNA (Citosina-5-)-Metiltransferases/metabolismo , Metilação de DNA/genética , Progressão da Doença , Feminino , Transplante de Células-Tronco Hematopoéticas , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/efeitos dos fármacos , Humanos , Camundongos Endogâmicos C57BL , Monócitos/efeitos dos fármacos , Monócitos/patologia , Células Mieloides/efeitos dos fármacos , Células Mieloides/metabolismo , Células Mieloides/patologia , Células-Tronco Neoplásicas/efeitos dos fármacos , Oncogenes , Regiões Promotoras Genéticas/genética , Transdução de Sinais/efeitos dos fármacos , Análise de Sobrevida , Ensaio Tumoral de Célula-TroncoRESUMO
Mantle cell lymphoma (MCL) is one of the most frequent of the newly recognized non-Hodgkin's lymphomas. The major problem of MCL therapy is the occurrence of relapse and subsequent resistance to chemotherapy and immunotherapy in virtually all cases. Here, we show that one injection of anti-human transferrin receptor (TfR) monoclonal antibody A24 totally prevented xenografted MCL tumor establishment in nude mice. It also delayed and inhibited tumor progression of established tumors, prolonging mice survival. In vitro, A24 induced up to 85% reduction of MCL cell proliferation (IC(50) = 3.75 nmol/L) independently of antibody aggregation, complement-dependent or antibody-dependent cell-mediated cytotoxicity. A24 induced MCL cell apoptosis through caspase-3 and caspase-9 activation, either alone or synergistically with chemotherapeutic agents. A24 induced TfR endocytosis via the clathrin adaptor protein-2 complex pathway followed by transport to lysosomal compartments. Therefore, A24-based therapies alone or in association with classic chemotherapies could provide a new alternative strategy against MCL, particularly in relapsing cases.
Assuntos
Anticorpos Monoclonais/farmacologia , Imunização Passiva/métodos , Linfoma de Célula do Manto/prevenção & controle , Lisossomos/metabolismo , Receptores da Transferrina/metabolismo , Animais , Apoptose/efeitos dos fármacos , Ciclo Celular/efeitos dos fármacos , Processos de Crescimento Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Endocitose/efeitos dos fármacos , Feminino , Humanos , Linfonodos/metabolismo , Linfonodos/patologia , Linfoma de Célula do Manto/metabolismo , Linfoma de Célula do Manto/patologia , Camundongos , Camundongos Nus , Receptores da Transferrina/imunologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Fc receptors (FcRs) belong to the ITAM-associated receptor family. FcRs control the humoral and innate immunity which are essential for appropriate responses to infections and prevention of chronic inflammation or auto-immune diseases. Following their crosslinking by immune complexes, FcRs play various roles such as modulation of the immune response by released cytokines or of phagocytosis. Here, we review FcR involvement in pathologies leading notably to altered intracellular signaling with functionally relevant consequences to the host, and targeting of Fc receptors as therapeutic approaches. Special emphasis will be given to some FcRs, such as the FcαRI, the FcγRIIA and the FcγRIIIA, which behave like the ancient god Janus depending on the ITAM motif to inhibit or activate immune responses depending on their targeting by monomeric/dimeric immunoglobulins or by immune complexes. This ITAM duality has been recently defined as inhibitory or activating ITAM (ITAMi or ITAMa) which are controlled by Src family kinases. Involvement of various ITAM-bearing FcRs observed during infectious or autoimmune diseases is associated with allelic variants, changes in ligand binding ability responsible for host defense perturbation. During auto-immune diseases such as rheumatoid arthritis, lupus or immune thrombocytopenia, the autoantibodies and immune complexes lead to inflammation through FcR aggregation. We will discuss the role of FcRs in autoimmune diseases, and focus on novel approaches to target FcRs for resolution of antibody-mediated autoimmunity. We will finally also discuss the down-regulation of FcR functionality as a therapeutic approach for autoimmune diseases.
Assuntos
Inflamação/imunologia , Receptores Fc/imunologia , Animais , Complexo Antígeno-Anticorpo/imunologia , Doenças Autoimunes/imunologia , Humanos , Imunidade Inata/imunologia , Transdução de Sinais/imunologiaRESUMO
Direct bacterial recognition by innate receptors is crucial for bacterial clearance. Here, we show that the IgA receptor CD89 is a major innate receptor that directly binds bacteria independently of its cognate ligands IgA and c-reactive protein (CRP). This binding is only partially inhibited by serum IgA and induces bacterial phagocytosis by CD11c+ dendritic cells and monocytes and/or macrophages, suggesting a physiological role in innate host defense. Blood phagocytes from common variable immunodeficiency patients bind, internalize, and kill bacteria in a CD89-dependent manner, confirming the IgA independence of this mechanism. In vivo, CD89 transgenic mice are protected in two different models of sepsis: a model of pneumonia and the cecal ligation and puncture (CLP) polymicrobial model of infection. These data identify CD89 as a first-line innate receptor for bacterial clearance before adaptive responses can be mounted. Fc receptors may emerge as a class of innate receptors for various bacteria with pleiotropic roles.
Assuntos
Antígenos CD/metabolismo , Escherichia coli/fisiologia , Receptores Fc/metabolismo , Sepse/prevenção & controle , Streptococcus pneumoniae/fisiologia , Animais , Antígenos CD/genética , Proteína C-Reativa/metabolismo , Citocinas/metabolismo , Células Dendríticas/citologia , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Modelos Animais de Doenças , Feminino , Humanos , Hospedeiro Imunocomprometido , Imunoglobulina A/sangue , Imunoglobulina A/imunologia , Imunoglobulina A/metabolismo , Estimativa de Kaplan-Meier , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Monócitos/citologia , Monócitos/imunologia , Monócitos/metabolismo , Fagocitose , Pneumonia/mortalidade , Pneumonia/patologia , Receptores Fc/genética , Sepse/imunologiaRESUMO
Compelling evidence points to a role for IgA receptors in the pathogenesis of IgA nephropathy. The soluble form of the type I IgA receptor (FcalphaRI or CD89) forms complexes with IgA that can be found in patients' serum and that initiate the disease in CD89 transgenic mice. A nonclassic IgA receptor, identified as the transferrin receptor (TfR), is highly expressed in patients' mesangium and colocalizes with IgA deposits. TfR preferentially binds polymeric IgA1 complexes, but not monomeric IgA1 or IgA2. The TfR-IgA1 interaction is dependent on carbohydrate moieties because hypoglycosylated IgA1 has superior binding to TfR than normally glycosylated IgA1. Polymeric IgA1 binding enhances mesangial cell TfR expression and results in cell proliferation and inflammatory and profibrogenic cytokine and chemokine production, suggesting a pivotal role in mesangial cell proliferation, matrix expansion, and recruitment of inflammatory cells. We propose that, as a second event, activation of the classic, FcRgamma-associated transmembrane FcalphaRI expressed on circulating myeloid leukocytes takes place. FcalphaRI/gamma2 cross-linking in human FcalphaRI transgenic animals promotes disease progression by enhancing leukocyte chemotaxis and cytokine production, and IgA immune complexes from IgA nephropathy patients induce FcalphaRI-dependent cell activation. This review therefore details the functional consequences of IgA/receptor interactions and discusses proposed mechanisms to explain the development and chronicity of the disease.