RESUMEN
AIMS: The adaptive immune response plays an important role in atherosclerosis. In response to a high-fat/high-cholesterol (HF/HC) diet, marginal zone B (MZB) cells activate an atheroprotective programme by regulating the differentiation and accumulation of 'poorly differentiated' T follicular helper (Tfh) cells. On the other hand, Tfh cells activate the germinal centre response, which promotes atherosclerosis through the production of class-switched high-affinity antibodies. We therefore investigated the direct role of Tfh cells and the role of IL18 in Tfh differentiation in atherosclerosis. METHODS AND RESULTS: We generated atherosclerotic mouse models with selective genetic deletion of Tfh cells, MZB cells, or IL18 signalling in Tfh cells. Surprisingly, mice lacking Tfh cells had increased atherosclerosis. Lack of Tfh not only reduced class-switched IgG antibodies against oxidation-specific epitopes (OSEs) but also reduced atheroprotective natural IgM-type anti-phosphorylcholine (PC) antibodies, despite no alteration of natural B1 cells. Moreover, the absence of Tfh cells was associated with an accumulation of MZB cells with substantially reduced ability to secrete antibodies. In the same manner, MZB cell deficiency in Ldlr-/- mice was associated with a significant decrease in atheroprotective IgM antibodies, including natural anti-PC IgM antibodies. In humans, we found a positive correlation between circulating MZB-like cells and anti-OSE IgM antibodies. Finally, we identified an important role for IL18 signalling in HF/HC diet-induced Tfh. CONCLUSION: Our findings reveal a previously unsuspected role of MZB cells in regulating atheroprotective 'natural' IgM antibody production in a Tfh-dependent manner, which could have important pathophysiological and therapeutic implications.
Asunto(s)
Aterosclerosis , Interleucina-18 , Humanos , Ratones , Animales , Inmunoglobulina M , Linfocitos B , Aterosclerosis/genética , Aterosclerosis/prevención & control , Colesterol , Linfocitos T Colaboradores-InductoresRESUMEN
BACKGROUND: Innate lymphoid cells type 2 (ILC2s) play critical homeostatic functions in peripheral tissues. ILC2s reside in perivascular niches and limit atherosclerosis development. OBJECTIVES: ILC2s also reside in the pericardium but their role in postischemic injury is unknown. METHODS: We examined the role of ILC2 in a mouse model of myocardial infarction (MI), and compared mice with or without genetic deletion of ILC2. We determined infarct size using histology and heart function using echocardiography. We assessed cardiac ILC2 using flow cytometry and RNA sequencing. Based on these data, we devised a therapeutic strategy to activate ILC2 in mice with acute MI, using exogenous interleukin (IL)-2. We also assessed the ability of low-dose IL-2 to activate ILC2 in a double-blind randomized clinical trial of patients with acute coronary syndromes (ACS). RESULTS: We found that ILC2 levels were increased in pericardial adipose tissue after experimental MI, and genetic ablation of ILC2 impeded the recovery of heart function. RNA sequencing revealed distinct transcript signatures in ILC2, and pointed to IL-2 axis as a major upstream regulator. Treatment of T-cell-deficient mice with IL-2 (to activate ILC2) significantly improved the recovery of heart function post-MI. Administration of low-dose IL-2 to patients with ACS led to activation of circulating ILC2, with significant increase in circulating IL-5, a prototypic ILC2-derived cytokine. CONCLUSIONS: ILC2s promote cardiac healing and improve the recovery of heart function after MI in mice. Activation of ILC2 using low-dose IL-2 could be a novel therapeutic strategy to promote a reparative response after MI.
Asunto(s)
Síndrome Coronario Agudo , Interleucina-2 , Linfocitos , Infarto del Miocardio , Recuperación de la Función , Animales , Femenino , Síndrome Coronario Agudo/tratamiento farmacológico , Tejido Adiposo/inmunología , Interleucina-2/metabolismo , Interleucina-2/uso terapéutico , Linfocitos/fisiología , Ratones Endogámicos C57BL , Infarto del Miocardio/inmunología , Infarto del Miocardio/metabolismo , Recuperación de la Función/inmunología , Función VentricularRESUMEN
OBJECTIVE: Neuroimmune interactions between the sympathetic nervous system (SNS) and macrophages are required for the homeostasis of multiple tissues, including the adipose tissue. It has been proposed that the SNS maintains adipose tissue macrophages (ATMs) in an anti-inflammatory state via direct norepinephrine (NE) signaling to macrophages. This study aimed to investigate the physiological importance of this paradigm by utilizing a mouse model in which the adrenergic signaling from the SNS to macrophages, but not to other adipose tissue cells, was disrupted. METHODS: We generated a macrophage-specific B2AR knockout mouse (Adrb2ΔLyz2) by crossing Adrb2fl/fl and Lyz2Cre/+ mice. We have previously shown that macrophages isolated from Adrb2ΔLyz2 animals do not respond to NE stimulation in vitro. Herein we performed a metabolic phenotyping of Adrb2ΔLyz2 mice on either chow or high-fat diet (HFD). We also assessed the adipose tissue function of Adrb2ΔLyz2 animals during fasting and cold exposure. Finally, we transplanted Adrb2ΔLyz2 bone marrow to low-density lipoprotein receptor (LDLR) knockout mice and investigated the development of atherosclerosis during Western diet feeding. RESULTS: We demonstrated that SNS-associated ATMs have a transcriptional profile indicative of activated beta-2 adrenergic receptor (B2AR), the main adrenergic receptor isoform in myeloid cells. However, Adrb2ΔLyz2 mice have unaltered energy balance on a chow or HFD. Furthermore, Adrb2ΔLyz2 mice show similar levels of adipose tissue inflammation and function during feeding, fasting, or cold exposure, and develop insulin resistance during HFD at the same rate as controls. Finally, macrophage-specific B2AR deletion does not affect the development of atherosclerosis on an LDL receptor-null genetic background. CONCLUSIONS: Overall, our data suggest that the SNS does not directly modulate the phenotype of adipose tissue macrophages in either lean mice or mouse models of cardiometabolic disease. Instead, sympathetic nerve activity exerts an indirect effect on adipose tissue macrophages through the modulation of adipocyte function.
Asunto(s)
Aterosclerosis/complicaciones , Aterosclerosis/metabolismo , Resistencia a la Insulina/genética , Macrófagos/metabolismo , Obesidad/complicaciones , Obesidad/metabolismo , Paniculitis/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Transducción de Señal/genética , Adipocitos/metabolismo , Tejido Adiposo Blanco/metabolismo , Animales , Aterosclerosis/genética , Trasplante de Médula Ósea/métodos , Células Cultivadas , Dieta Alta en Grasa/efectos adversos , Dieta Occidental/efectos adversos , Modelos Animales de Enfermedad , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Obesidad/genética , Paniculitis/genética , Fenotipo , Receptores Adrenérgicos beta 2/genética , Sistema Nervioso Simpático/metabolismoRESUMEN
Splenic red pulp macrophages (RPMs) contribute to erythrocyte homeostasis and are required for iron recycling. Heme induces the expression of SPIC transcription factor in monocyte-derived macrophages and promotes their differentiation into RPM precursors, pre-RPMs. However, the requirements for differentiation into mature RPMs remain unknown. Here, we have demonstrated that interleukin (IL)-33 associated with erythrocytes and co-cooperated with heme to promote the generation of mature RPMs through activation of the MyD88 adaptor protein and ERK1/2 kinases downstream of the IL-33 receptor, IL1RL1. IL-33- and IL1RL1-deficient mice showed defective iron recycling and increased splenic iron deposition. Gene expression and chromatin accessibility studies revealed a role for GATA transcription factors downstream of IL-33 signaling during the development of pre-RPMs that retained full potential to differentiate into RPMs. Thus, IL-33 instructs the development of RPMs as a response to physiological erythrocyte damage with important implications to iron recycling and iron homeostasis.
Asunto(s)
Proteína 1 Similar al Receptor de Interleucina-1/inmunología , Interleucina-33/inmunología , Hierro/metabolismo , Macrófagos/inmunología , Transducción de Señal/inmunología , Bazo/metabolismo , Animales , Eritrocitos/inmunología , Eritrocitos/metabolismo , Hemo/inmunología , Hemo/metabolismo , Homeostasis/inmunología , Proteína 1 Similar al Receptor de Interleucina-1/genética , Proteína 1 Similar al Receptor de Interleucina-1/metabolismo , Interleucina-33/genética , Interleucina-33/metabolismo , Macrófagos/metabolismo , Ratones Noqueados , Proteína Quinasa 1 Activada por Mitógenos/inmunología , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/inmunología , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Factor 88 de Diferenciación Mieloide/inmunología , Factor 88 de Diferenciación Mieloide/metabolismo , Bazo/citologíaRESUMEN
Regulatory T cells and type-2 innate lymphoid cells represent 2 subsets of immune cells, which have been shown in preclinical models to be important in atherosclerosis and myocardial repair. Regulatory T cells play a crucial role in immune homeostasis and tolerance via their interactions with effector T cells, dendritic cells, and monocytes/macrophages. They also utilize and secrete inhibitory cytokines, including interleukin 10 and transforming growth factor ß, to regulate or suppress pathogenic immune responses. Type-2 innate lymphoid cells have an important role in type-2 immune responses and tissue repair through secreting interleukins 5 and 13, as well as a variety of biological mediators and growth factors. Intriguingly, interleukin-2 has emerged as a common cytokine, which can be harnessed to upregulate both cell types, and also has important translational consequences as clinical trials are ongoing for its use in cardiovascular disease. Here, we briefly review the biology of these regulatory immune cell types, discuss the preclinical and clinical evidence for their functions in cardiovascular disease, examine the prospects for clinical translation and current ongoing trials, and finally, postulate how overlap in the mechanisms of upregulation may be leveraged in future treatments for patients.
Asunto(s)
Inmunidad Adaptativa , Enfermedades Cardiovasculares/tratamiento farmacológico , Enfermedades Cardiovasculares/inmunología , Inmunidad Innata , Interleucina-2/uso terapéutico , Animales , Humanos , Interleucina-13/inmunología , Interleucina-5/inmunología , Linfocitos T Reguladores/inmunologíaRESUMEN
OBJECTIVE: MARK4 (microtubule affinity-regulating kinase 4) regulates NLRP3 (nucleotide-binding oligomerization domain, leucine-rich repeat, and pyrin domain containing 3) inflammasome activation. The aim of the study is to examine the role of MARK4 in hematopoietic cells during atherosclerosis. METHODS AND RESULTS: We show increased MARK4 expression in human atherosclerotic lesions compared with adjacent areas. MARK4 is coexpressed with NLRP3, and they colocalize in areas enriched in CD68-positive but α-SMA (α-smooth muscle actin)-negative cells. Expression of MARK4 and NLRP3 in the atherosclerotic lesions is associated with the production of active IL (interleukin)-1ß and IL-18. To directly assess the role of hematopoietic MARK4 in NLRP3 inflammasome activation and atherosclerotic plaque formation, Ldlr (low-density lipoprotein receptor)-deficient mice were lethally irradiated and reconstituted with either wild-type or Mark4-deficient bone marrow cells, and were subsequently fed a high-fat diet and cholesterol diet for 9 weeks. Mark4 deficiency in bone marrow cells led to a significant reduction of lesion size, together with decreased circulating levels of IL-18 and IFN-γ (interferon-γ). Furthermore, Mark4 deficiency in primary murine bone marrow-derived macrophages prevented cholesterol crystal-induced NLRP3 inflammasome activation, as revealed by reduced caspase-1 activity together with reduced production of IL-1ß and IL-18. CONCLUSIONS: MARK4-dependent NLRP3 inflammasome activation in the hematopoietic cells regulates the development of atherosclerosis.
Asunto(s)
Aterosclerosis/etiología , Inflamasomas/fisiología , Proteína con Dominio Pirina 3 de la Familia NLR/fisiología , Proteínas Serina-Treonina Quinasas/fisiología , Anciano , Anciano de 80 o más Años , Animales , Células Cultivadas , Humanos , Interleucina-18/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , Receptores de LDL/fisiologíaRESUMEN
RATIONALE: Despite an established role for adaptive immune responses in atherosclerosis, the contribution of dendritic cells (DCs) and their various subsets is still poorly understood. OBJECTIVE: Here, we address the role of IRF8 (interferon regulatory factor 8)-dependent DCs (lymphoid CD8α+ and their developmentally related nonlymphoid CD103+ DCs) in the induction of proatherogenic immune responses during high fat feeding. METHODS AND RESULTS: Using a fate-mapping technique to track DCs originating from a DNGR1+ (dendritic cell natural killer lectin group receptor 1) precursor (Clec9a+/creRosa+/EYFP mice), we first show that YFPhiCD11chiMHCIIhi (major histocompatibility complex class II) DCs are present in the atherosclerotic aorta of low-density lipoprotein receptor-deficient (Ldlr-/-) mice and are CD11b-CD103+IRF8hi. Restricted deletion of IRF8 in DCs (Irf8flox/floxCd11cCre ) reduces the accumulation of CD11chiMHCIIhi DCs in the aorta without affecting CD11b+CD103- DCs or macrophages but completely abolishes the accumulation of aortic CD11b-CD103+ DCs. Lymphoid CD8α+ DCs are also deleted. This is associated with a significant reduction of aortic T-cell accumulation and a marked reduction of high-fat diet-induced systemic T-cell priming, activation, and differentiation toward T helper type 1 cells, T follicular helper cells, and regulatory T cells. As a consequence, B-cell activation and germinal center responses to high-fat diet are also markedly reduced. IRF8 deletion in DCs significantly reduces the development of atherosclerosis, predominantly in the aortic sinus, despite a modest increase in total plasma cholesterol levels. CONCLUSIONS: IRF8 expression in DCs plays a nonredundant role in the development of proatherogenic adaptive immunity.
Asunto(s)
Inmunidad Adaptativa , Aterosclerosis/inmunología , Células Dendríticas/inmunología , Factores Reguladores del Interferón/metabolismo , Animales , Aorta/citología , Aterosclerosis/etiología , Antígenos CD11/genética , Antígenos CD11/metabolismo , Células Cultivadas , Dieta Alta en Grasa/efectos adversos , Femenino , Antígenos de Histocompatibilidad Clase II/genética , Antígenos de Histocompatibilidad Clase II/metabolismo , Factores Reguladores del Interferón/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Linfocitos T/inmunologíaRESUMEN
RATIONALE: Diverse B cell responses and functions may be involved in atherosclerosis. Protective antibody responses, such as those against oxidized lipid epitopes, are thought to mainly derive from T cell-independent innate B cell subsets. In contrast, both pathogenic and protective roles have been associated with T cell-dependent antibodies, and their importance in both humans and mouse models is still unclear. OBJECTIVE: To specifically target antibody production by plasma cells and determine the impact on atherosclerotic plaque development in mice with and without CD4+ T cells. METHODS AND RESULTS: We combined a model of specific antibody deficiency, B cell-specific CD79a-Cre x XBP1 (X-box binding protein-1) floxed mice (XBP1-conditional knockout), with antibody-mediated depletion of CD4+ T cells. Ldlr knockout mice transplanted with XBP1-conditional knockout (or wild-type control littermate) bone marrow were fed western diet for 8 weeks with or without anti-CD4 depletion. All groups had similar levels of serum cholesterol. In Ldlr/XBP1-conditional knockout mice, serum levels of IgG, IgE, and IgM were significantly attenuated, and local antibody deposition in atherosclerotic plaque was absent. Antibody deficiency significantly accelerated atherosclerosis at both the aortic root and aortic arch. T cell and monocyte responses were not modulated, but necrotic core size was greater, even when adjusting for plaque size, and collagen deposition significantly lower. Anti-CD4 depletion in Ldlr/wild-type mice led to a decrease of serum IgG1 and IgG2c but not IgG3, as well as decreased IgM, associated with increased atherosclerosis and necrotic cores, and a decrease in plaque collagen. The combination of antibody deficiency and anti-CD4 depletion has no additive effects on aortic root atherosclerosis. CONCLUSIONS: The endogenous T cell-dependent humoral response can be protective. This has important implications for novel vaccine strategies for atherosclerosis and in understanding the impacts of immunotherapies used in patients at high risk for cardiovascular disease.
Asunto(s)
Aterosclerosis/metabolismo , Linfocitos B/metabolismo , Linfocitos T/metabolismo , Proteína 1 de Unión a la X-Box/deficiencia , Animales , Aterosclerosis/inmunología , Aterosclerosis/patología , Linfocitos B/inmunología , Inmunidad Humoral/fisiología , Masculino , Ratones , Ratones Noqueados , Células Plasmáticas/inmunología , Células Plasmáticas/metabolismo , Linfocitos T/inmunología , Proteína 1 de Unión a la X-Box/inmunologíaRESUMEN
Type-2 innate lymphoid cells (ILC2) are a prominent source of type II cytokines and are found constitutively at mucosal surfaces and in visceral adipose tissue. Despite their role in limiting obesity, how ILC2s respond to high fat feeding is poorly understood, and their direct influence on the development of atherosclerosis has not been explored. Here, we show that ILC2 are present in para-aortic adipose tissue and lymph nodes and display an inflammatory-like phenotype atypical of adipose resident ILC2. High fat feeding alters both the number of ILC2 and their type II cytokine production. Selective genetic ablation of ILC2 in Ldlr-/- mice accelerates the development of atherosclerosis, which is prevented by reconstitution with wild type but not Il5-/- or Il13-/- ILC2. We conclude that ILC2 represent a major innate cell source of IL-5 and IL-13 required for mounting atheroprotective immunity, which can be altered by high fat diet.
Asunto(s)
Aterosclerosis/patología , Linfocitos/patología , Tejido Adiposo Blanco/patología , Animales , Aorta/metabolismo , Aorta/patología , Aterosclerosis/etiología , Trasplante de Médula Ósea , Citocinas/metabolismo , Dieta Alta en Grasa/efectos adversos , Femenino , Interleucina-13/metabolismo , Interleucina-5/metabolismo , Linfocitos/metabolismo , Ratones Noqueados para ApoE , Ratones Mutantes , Placa Aterosclerótica/patologíaRESUMEN
The T2 ribonuclease omega-1 is a powerful Th2-inducing factor secreted by the eggs of the blood fluke Schistosoma mansoni. Omega-1 can modulate pattern recognition receptor-induced inflammatory signatures and alter antigen presentation by dendritic cells. Recent findings have suggested that component(s) contained in or secreted by S. mansoni eggs (soluble egg antigen) can also enhance IL-1ß secretion by dendritic cells stimulated with pattern recognition receptor ligands. Here we show that omega-1 enhances IL-1ß secretion in macrophages stimulated with Toll-like receptor 2 ligand, and propose omega-1 as the factor in soluble egg antigen capable of regulating inflammasome activity. This effect is dependent on the C-type lectin receptor Dectin-1, caspase-8 and the ASC inflammasome adaptor protein, highlighting the ability of omega-1 to regulate multiple pattern recognition receptor signalling pathways. These mechanistic insights into manipulation of host immunity by a parasite product have implications for the design of anti-inflammatory therapeutic drugs.
Asunto(s)
Antígenos Helmínticos/metabolismo , Proteínas del Huevo/metabolismo , Endorribonucleasas/inmunología , Inflamasomas/inmunología , Interleucina-1beta/inmunología , Macrófagos Peritoneales/inmunología , Schistosoma mansoni/inmunología , Animales , Caspasa 8/metabolismo , Células Dendríticas/inmunología , Células Dendríticas/metabolismo , Endorribonucleasas/metabolismo , Humanos , Inflamasomas/metabolismo , Interleucina-1beta/metabolismo , Lectinas Tipo C/inmunología , Lectinas Tipo C/metabolismo , Macrófagos Peritoneales/metabolismo , Ratones , Schistosoma mansoni/enzimología , Células Th2/inmunologíaRESUMEN
The spontaneous destruction of insulin producing pancreatic beta cells in non-obese diabetic (NOD) mice provides a valuable model of type 1 diabetes. As in humans, disease susceptibility is controlled by the classical MHC class II genes that guide CD4(+) T cell responses to self and foreign antigens. It has long been suspected that the dedicated class II chaperone designated HLA-DM in humans or H-2M in mice also makes an important contribution, but due to tight linkage within the MHC, a possible role played by DM peptide editing has not been previously tested by conventional genetic approaches. Here we exploited newly established germ-line competent NOD ES cells to engineer a loss of function allele. DM deficient NOD mice display defective class II peptide occupancy and surface expression, and are completely protected against type 1 diabetes. Interestingly the mutation results in increased proportional representation of CD4(+)Foxp3(+) regulatory T cells and the absence of pathogenic CD4(+) T effectors. Overall, this striking phenotype establishes that DM-mediated peptide selection plays an essential role in the development of autoimmune diabetes in NOD mice.
Asunto(s)
Diabetes Mellitus Tipo 1/inmunología , Células Madre Embrionarias/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Linfocitos T Reguladores/inmunología , Animales , Antígenos de Diferenciación de Linfocitos B/genética , Antígenos de Diferenciación de Linfocitos B/inmunología , Antígenos de Diferenciación de Linfocitos B/metabolismo , Western Blotting , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/metabolismo , Células Madre Embrionarias/metabolismo , Femenino , Factores de Transcripción Forkhead/inmunología , Factores de Transcripción Forkhead/metabolismo , Predisposición Genética a la Enfermedad/genética , Antígenos de Histocompatibilidad Clase II/genética , Antígenos de Histocompatibilidad Clase II/metabolismo , Humanos , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Endogámicos NOD , Ratones Noqueados , Ratones SCID , Microscopía Confocal , Linfocitos T Reguladores/metabolismo , Timo/inmunología , Timo/metabolismoRESUMEN
Increasingly, evidence suggests that there is a strong environmental component to the development of the autoimmune disease type 1 diabetes. Our previous data showed that NOD mice are protected from developing diabetes after infection with Salmonella typhimurium and there is some evidence that changes within the DC compartment play a crucial role in this protective effect. This paper further characterises this Salmonella-modulated protective phenotype. We find that, contrary to other infection-mediated models of type 1 diabetes protection, there was no expansion of Foxp3(+) Tregs. Furthermore, transcriptome analysis of DCs identified a distinct Salmonella-induced signature in which the inhibitory receptor PD-L1 was up-regulated. This was confirmed by flow cytometry. In vivo blockade of the PD1/PD-L1 interaction was found to ablate the protective function of Salmonella infection. These data provide evidence for a novel regulatory DC phenotype proficient at controlling autoreactive T cells for an extended duration in the NOD mouse model of diabetes.
Asunto(s)
Antígeno B7-H1/metabolismo , Diabetes Mellitus Tipo 1/inmunología , Diabetes Mellitus Tipo 1/prevención & control , Salmonelosis Animal/inmunología , Salmonella typhimurium/inmunología , Linfocitos T Reguladores/metabolismo , Animales , Antígeno B7-H1/genética , Linfocitos T CD4-Positivos/inmunología , Proliferación Celular , Ciclofosfamida/farmacología , Células Dendríticas , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/microbiología , Citometría de Flujo , Factores de Transcripción Forkhead/biosíntesis , Perfilación de la Expresión Génica , Subunidad alfa del Receptor de Interleucina-2 , Activación de Linfocitos/inmunología , Ratones , Ratones Endogámicos NOD , Ratones Transgénicos , Linfocitos T Reguladores/inmunología , Regulación hacia ArribaRESUMEN
Nonobese diabetic (NOD) mice provide an excellent model of type 1 diabetes. The genetic contribution to this disease is complex, with more than 20 loci implicated in diabetes onset. One of the challenges for researchers using the NOD mouse model (and, indeed, other models of spontaneous autoimmune disease) has been the high density of sequence variation within candidate chromosomal segments. Furthermore, the scope for analyzing many putative disease loci via gene targeting has been hampered by the lack of NOD embryonic stem (ES) cells. We describe here the derivation of NOD ES cell lines capable of generating chimeric mice after stable genetic modification. These NOD ES cell lines also show efficient germline transmission, with offspring developing diabetes. The availability of these cells will not only enable the dissection of closely linked loci and the role they have in the onset of type 1 diabetes but also facilitate the generation of new transgenics.
Asunto(s)
Diabetes Mellitus Tipo 1/etiología , Células Madre Embrionarias/citología , Animales , Línea Celular , Quimera , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos NODRESUMEN
Copy number (CN) variation (CNV) has been shown to be common in regions of the genome coding for immune-related genes, and thus impacts upon polygenic autoimmunity. Low CN of FCGR3B has recently been associated with systemic lupus erythematosus (SLE). FcgammaRIIIb is a glycosylphosphatidylinositol-linked, low affinity receptor for IgG found predominantly on human neutrophils. We present novel data demonstrating that both in a family with FcgammaRIIIb-deficiency and in the normal population, FCGR3B CNV correlates with protein expression, with neutrophil uptake of and adherence to immune complexes, and with soluble serum FcgammaRIIIb. Reduced FcgammaRIIIb expression is thus likely to contribute to the impaired clearance of immune complexes, which is a feature of SLE, explaining the association between low FCGR3B CNV and SLE that we have confirmed in a Caucasian population. In contrast, antineutrophil cytoplasmic antibody-associated systemic vasculitis (AASV), a disease not associated with immune complex deposition, is associated with high FCGR3B CN. Thus, we define a role for FCGR3B CNV in immune complex clearance, a function that may explain why low FCGR3B CNV is associated with SLE, but not AASV. This is the first report of an association between disease-related gene CNV and variation in protein expression and function that may contribute to autoimmune disease susceptibility.
Asunto(s)
Complejo Antígeno-Anticuerpo/genética , Dosificación de Gen/genética , Regulación de la Expresión Génica/genética , Predisposición Genética a la Enfermedad , Variación Genética , Lupus Eritematoso Sistémico/inmunología , Receptores de IgG/genética , Anticuerpos Anticitoplasma de Neutrófilos/inmunología , Complejo Antígeno-Anticuerpo/inmunología , Autoinmunidad/genética , Femenino , Proteínas Ligadas a GPI , Dosificación de Gen/inmunología , Regulación de la Expresión Génica/inmunología , Variación Genética/inmunología , Humanos , Lupus Eritematoso Sistémico/genética , Masculino , Neutrófilos/inmunología , Receptores de IgG/inmunología , Vasculitis/genética , Vasculitis/inmunología , Población BlancaRESUMEN
The G6B cell-surface receptor, which contains a single Ig-like domain, has been shown to bind to SHP-1 and SHP-2 after phosphorylation of 2 immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in its cytoplasmic tail, classifying this protein as a new member of the family of inhibitory receptors. In this study, we demonstrate by real-time polymerase chain reaction (PCR) and Western-blot analysis that G6B is expressed on platelets. Cross-linking of G6B with polyclonal antisera has a significant inhibitory effect on platelet aggregation and activation by agonists such as ADP and collagen-related peptide (CRP). This inhibitory function of G6B appears to operate in a calcium-independent manner. Our results suggest that G6B represents a novel inhibitory receptor found on the surface of platelets and that it could be an antithrombotic drug target.
Asunto(s)
Plaquetas/metabolismo , Membrana Celular/metabolismo , Regulación de la Expresión Génica , Proteínas de la Membrana/metabolismo , Receptores Inmunológicos/biosíntesis , Receptores Inmunológicos/fisiología , Adenosina Difosfato/química , Western Blotting , Proteínas Portadoras/química , Reactivos de Enlaces Cruzados/farmacología , Citoplasma/metabolismo , Humanos , Péptidos/química , Fosforilación , Isoformas de Proteínas , Estructura Terciaria de Proteína , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
The G6b gene, located in the human Major Histocompatibility Complex, encodes a receptor of the immunoglobulin (Ig) superfamily. In this study, we show using a variety of techniques that the extracellular domain of the G6b protein, containing a single Ig-like domain, binds to heparin with high affinity. In an ELISA assay, this binding was displaceable with soluble heparin with an IC50 value of approximately 0.5 microg/ml. Other sulfated glycans showed weaker or no competition. The observed interaction between G6b and heparin is strongly salt dependent suggesting a mainly electrostatic interaction. Heparin might modulate the interaction of G6b with its as yet unidentified protein ligand.