RESUMO
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.
Assuntos
Aterosclerose , Interleucina-18 , Humanos , Camundongos , Animais , Imunoglobulina M , Linfócitos B , Aterosclerose/genética , Aterosclerose/prevenção & controle , Colesterol , Linfócitos T Auxiliares-IndutoresRESUMO
AIMS: In pre-clinical models of acute myocardial infarction (MI), mature B cells mobilize inflammatory monocytes into the heart, leading to increased infarct size and deterioration of cardiac function, whilst anti-CD20 antibody-mediated depletion of B cells limits myocardial injury and improves cardiac function. Rituximab is a monoclonal anti-CD20 antibody targeted against human B cells. However, its use in cardiovascular disease is untested and is currently contraindicated. Therefore, we assessed the safety, feasibility, and pharmacodynamic effect of rituximab given to patients with acute ST-elevation MI (STEMI). METHODS AND RESULTS: Rituximab in patients with acute ST-elevation myocardial infarction (RITA-MI) was a prospective, open-label, dose-escalation, single-arm, phase 1/2a clinical trial, which tested rituximab administered as a single intravenous dose in patients with STEMI within 48 h of symptom onset. Four escalating doses (200, 500, 700, and 1000 mg) were used. The primary endpoint was safety, whilst secondary endpoints were changes in circulating immune cell subsets including B cells, and cardiac and inflammatory biomarkers. A total of 24 patients were dosed. Rituximab appeared well tolerated. Seven serious adverse events were reported, none of which were assessed as being related to the rituximab infusion. Rituximab caused a mean 96.3% (95% confidence interval 93.8-98.8%) depletion of circulating B cells within 30 min of starting the infusion. Maximal B-cell depletion was seen at Day 6, which was significantly lower than baseline for all doses (P < 0.001). B-cell repopulation at 6 months was dose-dependent, with modulation of returning B-cell subsets. Immunoglobulin (IgG, IgM, and IgA) levels were not affected during the 6 months of follow-up. CONCLUSIONS: A single infusion of rituximab appears safe when given in the acute STEMI setting and substantially alters circulating B-cell subsets. We provide important new insight into the feasibility and pharmacodynamics of rituximab in acute STEMI, which will inform further clinical translation of this potential therapy. CLINICAL TRIAL REGISTRATION: NCT03072199 at https://www.clinicaltrials.gov/.
Assuntos
Pesquisa Biomédica , Infarto do Miocárdio , Infarto do Miocárdio com Supradesnível do Segmento ST , Humanos , Estudos Prospectivos , Rituximab/efeitos adversos , Infarto do Miocárdio com Supradesnível do Segmento ST/diagnóstico , Infarto do Miocárdio com Supradesnível do Segmento ST/tratamento farmacológico , Resultado do TratamentoRESUMO
BACKGROUND: Atherosclerosis is a chronic inflammatory disease of the artery wall. Regulatory T cells (Tregs) limit inflammation and promote tissue healing. Low doses of interleukin (IL)-2 have the potential to increase Tregs, but its use is contraindicated for patients with ischemic heart disease. METHODS: In this randomized, double-blind, placebo-controlled, dose-escalation trial, we tested low-dose subcutaneous aldesleukin (recombinant IL-2), given once daily for 5 consecutive days. In study part A, the primary end point was safety, and patients with stable ischemic heart disease were randomly assigned to receive placebo or to one of five dose groups (range, 0.3 to 3.0 × 106 IU daily). In study part B, patients with acute non-ST elevation myocardial infarction or unstable angina were randomly assigned to receive placebo or to one of two dose groups (1.5 and 2.5 × 106 IU daily). The coprimary end points were safety and the dose required to increase circulating Tregs by 75%. Single-cell RNA-sequencing of circulating immune cells was used to provide a mechanistic assessment of the effects of aldesleukin. RESULTS: Forty-four patients were randomly assigned to either study part A (n=26) or part B (n=18). In total, 3 patients withdrew before dosing, 27 received active treatment, and 14 received placebo. The majority of adverse events were mild. Two serious adverse events occurred, with one occurring after drug administration. In parts A and B, there was a dose-dependent increase in Tregs. In part B, the estimated dose to achieve a 75% increase in Tregs was 1.46 × 106 IU (95% confidence interval, 1.06 to 1.87). Single-cell RNA-sequencing demonstrated the engagement of distinct pathways and cellcell interactions. CONCLUSIONS: In this phase 1b/2a study, low-dose IL-2 expanded Tregs without adverse events of major concern. Larger trials are needed to confirm the safety and to further evaluate the efficacy of low-dose IL-2 as an anti-inflammatory therapy for patients with ischemic heart disease. (Funded by the Medical Research Council, the British Heart Foundation, and others; ClinicalTrials.gov number, NCT03113773)
Assuntos
Interleucina-2 , Interleucina-2/análogos & derivados , Isquemia Miocárdica , Linfócitos T Reguladores , Humanos , Interleucina-2/administração & dosagem , Interleucina-2/uso terapêutico , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/efeitos dos fármacos , Isquemia Miocárdica/imunologia , Isquemia Miocárdica/tratamento farmacológico , Método Duplo-Cego , Masculino , Pessoa de Meia-Idade , Feminino , Proteínas RecombinantesRESUMO
OBJECTIVE: NR4A orphan receptors have been well studied in vascular and myeloid cells where they play important roles in the regulation of inflammation in atherosclerosis. NR4A1 (nerve growth factor IB) is among the most highly induced transcription factors in B cells following BCR (B-cell receptor) stimulation. Given that B cells substantially contribute to the development of atherosclerosis, we examined whether NR4A1 regulates B-cell function during atherogenesis. Approach and Results: We found that feeding Ldlr-/- mice a Western diet substantially increased Nr4a1 expression in marginal zone B (MZB) cells compared with follicular B cells. We then generated Ldlr-/- mice with complete B- or specific MZB-cell deletion of Nr4a1. Complete B-cell deletion of Nr4a1 led to increased atherosclerosis, which was accompanied by increased T follicular helper cell-germinal center axis response, as well as increased serum total cholesterol and triglycerides levels. Interestingly, specific MZB-cell deletion of Nr4a1 increased atherosclerosis in association with an increased T follicular helper-germinal center response but without any impact on serum cholesterol or triglyceride levels. Nr4a1-/- MZB cells showed decreased PDL1 (programmed death ligand-1) expression, which may have contributed to the enhanced T follicular helper response. CONCLUSIONS: Our findings reveal a previously unsuspected role for NR4A1 in the atheroprotective role of MZB cells.
Assuntos
Aorta/metabolismo , Doenças da Aorta/metabolismo , Aterosclerose/metabolismo , Linfócitos B/metabolismo , Deleção de Genes , Tecido Linfoide/metabolismo , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/deficiência , Animais , Aorta/patologia , Doenças da Aorta/genética , Doenças da Aorta/patologia , Aterosclerose/genética , Aterosclerose/patologia , Linfócitos B/patologia , Modelos Animais de Doenças , Progressão da Doença , Tecido Linfoide/patologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Membro 1 do Grupo A da Subfamília 4 de Receptores Nucleares/genética , Placa Aterosclerótica , Receptores de LDL/deficiência , Receptores de LDL/genética , Transdução de SinaisRESUMO
Objective- Investigate the impact of modulating B cell FcγRIIb (Fcγ receptor IIb) expression on atherosclerosis. Approach and Results- Western diet-induced atherosclerosis was assessed in Ldlr-/- or Apoe-/- mice with B cell-specific overexpression of FcγRIIb or with an FcγRIIb promoter mutation that alters FcγRIIb expression in germinal center (GC) B cells. In males, overexpression of FcγRIIb on B cells severely reduced activated, class switched B cell responses, as indicated by reductions in GC B cells, plasma cells, and serum IgG but not IgM antibodies. Male mice overexpressing FcγRIIb developed less atherosclerosis, suggesting a pathogenic role for GC B cell IgG responses. In support of this hypothesis, male mice with a promoter polymorphism-driven reduction in FcγRIIb on GC B cells but not plasma cells have a converse phenotype of enhanced GC responses and IgG2c antibodies and enhanced atherosclerosis. IgG2c significantly enhanced TNF (tumor necrosis factor) secretion by CD11b+ CD11c+ cells expressing the high-affinity receptor FcγRIV. In females, overexpression of FcγRIIb on B cells not only reduced GC B cell responses but also substantially reduced B-1 cells and IgM antibodies, which translated into acceleration of atherosclerosis. Promoter-driven reduction in FcγRIIb did not alter GC B cell responses in females and, therefore, had no impact on atherosclerosis. Conclusions- B cell FcγRIIb differentially alters proatherogenic adaptive GC B cell and atheroprotective innate B-1 responses in male and female mice fed a western diet. Our results highlight the importance of a better understanding and ability to selectively target B cell responses in future immunotherapeutic approaches against human cardiovascular disease. Visual Overview- An online visual overview is available for this article.
Assuntos
Aterosclerose/imunologia , Linfócitos B/imunologia , Centro Germinativo/imunologia , Receptores de IgG/fisiologia , Animais , Apolipoproteínas E/fisiologia , Feminino , Imunidade Inata , Imunoglobulina M/biossíntese , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fator de Necrose Tumoral alfa/biossínteseRESUMO
The cardiovascular system is subject to hyperlipidaemic, inflammatory, and pro-oxidant stressors. Over time, these factors drive prevalent chronic diseases, of which atherosclerosis is most prominent and accounts for the majority of deaths globally. Antibody-producing B cells perform a unique role in responses to stress, injury, and infection. The power, inducibility, and adaptability of the antibody repertoire require an equally complex range of control measures. Defects and chronic perturbations in these checkpoints lead to inappropriate antibody responses, which might have important roles in shaping the development and outcome of atherosclerotic disease. A unique aspect related to atherosclerosis is the prominent role of natural antibodies, specifically those binding to the oxidized epitopes that are abundant on modified lipoproteins and cellular debris. B cells control cellular immune responses through cell-cell contact, antigen presentation, and cytokine production, and thereby participate in systemic and local immune responses in atherosclerotic arteries. To date, both proatherogenic and antiatherogenic properties have been assigned to B cells, depending on subsets and how they are functionally targeted. For these reasons, a deeper understanding of how B cells influence atherosclerotic plaque development is being pursued with the hope of providing novel B cell-targeted interventions to prevent inflammation-driven cardiovascular events.
Assuntos
Aterosclerose/metabolismo , Subpopulações de Linfócitos B/metabolismo , Dislipidemias/metabolismo , Placa Aterosclerótica , Animais , Aterosclerose/imunologia , Aterosclerose/patologia , Aterosclerose/terapia , Autoimunidade , Subpopulações de Linfócitos B/imunologia , Subpopulações de Linfócitos B/patologia , Dislipidemias/imunologia , Dislipidemias/terapia , Humanos , Imunoterapia , Fenótipo , Receptores de Antígenos de Linfócitos B/imunologia , Receptores de Antígenos de Linfócitos B/metabolismo , Transdução de SinaisRESUMO
BACKGROUND: Atherosclerotic cardiovascular disease (heart attacks and strokes) is the major cause of death globally and is caused by the buildup of a plaque in the arterial wall. Genomic data showed that the B cell-activating factor (BAFF) receptor pathway, which is specifically essential for the survival of conventional B lymphocytes (B-2 cells), is a key driver of coronary heart disease. Deletion or antibody-mediated blockade of BAFF receptor ablates B-2 cells and decreases experimental atherosclerosis. Anti-BAFF immunotherapy is approved for treatment of autoimmune systemic lupus erythematosus, and can therefore be expected to limit their associated cardiovascular risk. However, direct effects of anti-BAFF immunotherapy on atherosclerosis remain unknown. METHODS: To investigate the effect of BAFF neutralization in atherosclerosis, the authors treated Apoe-/- and Ldlr-/- mice with a well-characterized blocking anti-BAFF antibody. Moreover, to investigate the mechanism by which BAFF impacts atherosclerosis, the authors studied atherosclerosis-prone mice that lack the alternative receptor for BAFF: transmembrane activator and calcium modulator and cyclophilin ligand interactor. RESULTS: The authors demonstrate here that anti-BAFF antibody treatment increased atherosclerosis in mice, despite efficient depletion of mature B-2 cells, suggesting a unique mechanism of action. Indeed, myeloid cell-specific deletion of transmembrane activator and calcium modulator and cyclophilin ligand interactor also results in increased atherosclerosis, while B cell-specific transmembrane activator and calcium modulator and cyclophilin ligand interactor deletion had no effect. Mechanistically, BAFF-transmembrane activator and calcium modulator and cyclophilin ligand interactor signaling represses macrophage IRF7-dependent (but not NF-κB-dependent) Toll-like receptor 9 responses including proatherogenic CXCL10 production. CONCLUSIONS: These data identify a novel B cell-independent anti-inflammatory role for BAFF in atherosclerosis and may have important clinical implications.
Assuntos
Anticorpos/uso terapêutico , Aterosclerose/terapia , Fator Ativador de Células B/imunologia , Animais , Anticorpos/imunologia , Aorta/patologia , Células da Medula Óssea/citologia , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Quimiocina CXCL10/genética , Quimiocina CXCL10/metabolismo , Colesterol/sangue , Imunoterapia , Fator Regulador 7 de Interferon/metabolismo , Macrófagos/citologia , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptor Toll-Like 9/metabolismo , Proteína Transmembrana Ativadora e Interagente do CAML/genética , Proteína Transmembrana Ativadora e Interagente do CAML/metabolismoRESUMO
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.
Assuntos
Aterosclerose/metabolismo , Linfócitos B/metabolismo , Linfócitos T/metabolismo , Proteína 1 de Ligação a X-Box/deficiência , Animais , Aterosclerose/imunologia , Aterosclerose/patologia , Linfócitos B/imunologia , Imunidade Humoral/fisiologia , Masculino , Camundongos , Camundongos Knockout , Plasmócitos/imunologia , Plasmócitos/metabolismo , Linfócitos T/imunologia , Proteína 1 de Ligação a X-Box/imunologiaRESUMO
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.
Assuntos
Aterosclerose/patologia , Linfócitos/patologia , Tecido Adiposo Branco/patologia , Animais , Aorta/metabolismo , Aorta/patologia , Aterosclerose/etiologia , Transplante de Medula Óssea , Citocinas/metabolismo , Dieta Hiperlipídica/efeitos adversos , Feminino , Interleucina-13/metabolismo , Interleucina-5/metabolismo , Linfócitos/metabolismo , Camundongos Knockout para ApoE , Camundongos Mutantes , Placa Aterosclerótica/patologiaRESUMO
Splenic marginal zone B (MZB) cells, positioned at the interface between circulating blood and lymphoid tissue, detect and respond to blood-borne antigens. Here we show that MZB cells in mice activate a homeostatic program in response to a high-cholesterol diet (HCD) and regulate both the differentiation and accumulation of T follicular helper (TFH) cells. Feeding mice an HCD resulted in upregulated MZB cell surface expression of the immunoregulatory ligand PDL1 in an ATF3-dependent manner and increased the interaction between MZB cells and pre-TFH cells, leading to PDL1-mediated suppression of TFH cell motility, alteration of TFH cell differentiation, reduced TFH abundance and suppression of the proatherogenic TFH response. Our findings reveal a previously unsuspected role for MZB cells in controlling the TFH-germinal center response to a cholesterol-rich diet and uncover a PDL1-dependent mechanism through which MZB cells use their innate immune properties to limit an exaggerated adaptive immune response.
Assuntos
Linfócitos B/imunologia , Antígeno B7-H1/imunologia , Colesterol na Dieta/imunologia , Dieta , Centro Germinativo/imunologia , Tecido Linfoide/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Fator 3 Ativador da Transcrição/genética , Fator 3 Ativador da Transcrição/imunologia , Animais , Aterosclerose/imunologia , Diferenciação Celular/imunologia , Movimento Celular/imunologia , Colesterol/sangue , HDL-Colesterol/sangue , Citometria de Fluxo , Homeostase , Humanos , Contagem de Linfócitos , Tecido Linfoide/citologia , Camundongos , Placa Aterosclerótica/sangue , Placa Aterosclerótica/imunologia , Placa Aterosclerótica/patologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Baço/citologia , Baço/imunologiaRESUMO
Cardiovascular diseases remain a major global health issue, with the development of atherosclerosis as a major underlying cause. Our treatment of cardiovascular disease has improved greatly over the past three decades, but much remains to be done reduce disease burden. Current priorities include reducing atherosclerosis advancement to clinically significant stages and preventing plaque rupture or erosion. Inflammation and involvement of the adaptive immune system influences all these aspects and therefore is one focus for future therapeutic development. The atherosclerotic vascular wall is now recognized to be invaded from both sides (arterial lumen and adventitia), for better or worse, by the adaptive immune system. Atherosclerosis is also affected at several stages by adaptive immune responses, overall providing many opportunities to target these responses and to reduce disease progression. Protective influences that may be defective in diseased individuals include humoral responses to modified LDL and regulatory T cell responses. There are many strategies in development to boost these pathways in humans, including vaccine-based therapies. The effects of various existing adaptive immune targeting therapies, such as blocking critical co-stimulatory pathways or B cell depletion, on cardiovascular disease are beginning to emerge with important consequences for both autoimmune disease patients and the potential for wider use of such therapies. Entering the translation phase for adaptive immune targeting therapies is an exciting and promising prospect. LINKED ARTICLES: This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.
Assuntos
Imunidade Adaptativa , Aterosclerose/tratamento farmacológico , Animais , Aterosclerose/imunologia , HumanosRESUMO
OBJECTIVE: To determine the role of regulatory B cell-derived interleukin (IL)-10 in atherosclerosis. APPROACH AND RESULTS: We created chimeric Ldlr(-/-) mice with a B cell-specific deficiency in IL-10, and confirmed that purified B cells stimulated with lipopolysaccharide failed to produce IL-10 compared with control Ldlr(-/-) chimeras. Mice lacking B-cell IL-10 demonstrated enhanced splenic B-cell numbers but no major differences in B-cell subsets, T cell or monocyte distribution, and unchanged body weights or serum cholesterol levels compared with control mice. After 8 weeks on high-fat diet, there were no differences in aortic root or aortic arch atherosclerosis. In addition to plaque size, plaque composition (macrophages, T cells, smooth muscle cells, and collagen) was similar between groups. CONCLUSIONS: In contrast to its prominent regulatory role in many immune-mediated diseases and its proposed modulatory role in atherosclerosis, B cell-derived IL-10 does not alter atherosclerosis in mice.
Assuntos
Aorta/metabolismo , Doenças da Aorta/metabolismo , Aterosclerose/metabolismo , Linfócitos B Reguladores/metabolismo , Interleucina-10/metabolismo , Animais , Aorta/imunologia , Aorta/patologia , Doenças da Aorta/sangue , Doenças da Aorta/genética , Doenças da Aorta/imunologia , Doenças da Aorta/patologia , Aterosclerose/sangue , Aterosclerose/genética , Aterosclerose/imunologia , Aterosclerose/patologia , Linfócitos B Reguladores/imunologia , Biomarcadores/sangue , Células Cultivadas , Dieta Hiperlipídica , Modelos Animais de Doenças , Interleucina-10/deficiência , Interleucina-10/genética , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Placa Aterosclerótica , Receptores de LDL/deficiência , Receptores de LDL/genética , Fatores de TempoRESUMO
OBJECTIVE: Atherosclerosis, the cause of 50% of deaths in westernized societies, is widely regarded as a chronic vascular inflammatory disease. Vascular smooth muscle cell (VSMC) inflammatory activation in response to local proinflammatory stimuli contributes to disease progression and is a pervasive feature in developing atherosclerotic plaques. Therefore, it is of considerable therapeutic importance to identify mechanisms that regulate the VSMC inflammatory response. APPROACH AND RESULTS: We report that myocardin, a powerful myogenic transcriptional coactivator, negatively regulates VSMC inflammatory activation and vascular disease. Myocardin levels are reduced during atherosclerosis, in association with phenotypic switching of smooth muscle cells. Myocardin deficiency accelerates atherogenesis in hypercholesterolemic apolipoprotein E(-/-) mice. Conversely, increased myocardin expression potently abrogates the induction of an array of inflammatory cytokines, chemokines, and adhesion molecules in VSMCs. Expression of myocardin in VSMCs reduces lipid uptake, macrophage interaction, chemotaxis, and macrophage-endothelial tethering in vitro, and attenuates monocyte accumulation within developing lesions in vivo. These results demonstrate that endogenous levels of myocardin are a critical regulator of vessel inflammation. CONCLUSIONS: We propose myocardin as a guardian of the contractile, noninflammatory VSMC phenotype, with loss of myocardin representing a critical permissive step in the process of phenotypic transition and inflammatory activation, at the onset of vascular disease.
Assuntos
Aterosclerose/metabolismo , Lesões das Artérias Carótidas/metabolismo , Inflamação/metabolismo , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/metabolismo , Proteínas Nucleares/metabolismo , Transativadores/metabolismo , Animais , Apolipoproteínas E/deficiência , Apolipoproteínas E/genética , Aterosclerose/genética , Aterosclerose/imunologia , Aterosclerose/patologia , Lesões das Artérias Carótidas/genética , Lesões das Artérias Carótidas/imunologia , Lesões das Artérias Carótidas/patologia , Adesão Celular , Moléculas de Adesão Celular/metabolismo , Células Cultivadas , Quimiocinas/metabolismo , Quimiotaxia , Citocinas/metabolismo , Modelos Animais de Doenças , Genótipo , Células Endoteliais da Veia Umbilical Humana/imunologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Inflamação/genética , Inflamação/imunologia , Inflamação/patologia , Metabolismo dos Lipídeos , Macrófagos/imunologia , Macrófagos/metabolismo , Masculino , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Monócitos/imunologia , Monócitos/metabolismo , Músculo Liso Vascular/imunologia , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/imunologia , Miócitos de Músculo Liso/patologia , Neointima , Proteínas Nucleares/deficiência , Proteínas Nucleares/genética , Fenótipo , Interferência de RNA , Ratos Wistar , Fatores de Tempo , Transativadores/deficiência , Transativadores/genética , TransfecçãoRESUMO
Atherosclerotic plaque formation is strongly influenced by different arms of the immune system, including B lymphocytes. B cells are divided into 2 main families: the B1 and the B2 cells. B1 cells are atheroprotective mainly via the production of natural IgM antibodies that bind oxidized low-density lipoprotein and apoptotic cells. B2 cells, which include follicular and marginal zone B cells, are suggested to be proatherogenic. Antibody-mediated depletion of B cells has become a valuable treatment option for certain autoimmune diseases, such as systemic lupus erythematosus and rheumatoid arthritis that are also characterized by the development of premature atherosclerosis. Thus, B cells represent a novel interesting target for therapeutic modulation of the atherosclerotic disease process. Here, we discuss the effect of different of B-cell subsets in experimental atherosclerosis, their mechanism of action as well as potential ways to exploit these findings for the treatment of human disease.
Assuntos
Aterosclerose/tratamento farmacológico , Subpopulações de Linfócitos B/efeitos dos fármacos , Fatores Imunológicos/uso terapêutico , Animais , Aterosclerose/imunologia , Aterosclerose/metabolismo , Aterosclerose/patologia , Subpopulações de Linfócitos B/imunologia , Subpopulações de Linfócitos B/metabolismo , Modelos Animais de Doenças , Humanos , Mediadores da Inflamação/imunologia , Mediadores da Inflamação/metabolismo , Terapia de Alvo Molecular , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/imunologia , Infarto do Miocárdio/metabolismo , Fenótipo , Transdução de Sinais/efeitos dos fármacos , Pesquisa Translacional BiomédicaRESUMO
BACKGROUND: Plasmacytoid dendritic cells (pDCs) bridge innate and adaptive immune responses and are important regulators of immuno-inflammatory diseases. However, their role in atherosclerosis remains elusive. METHODS AND RESULTS: Here, we used genetic approaches to investigate the role of pDCs in atherosclerosis. Selective pDC deficiency in vivo was achieved using CD11c-Cre × Tcf4(-/flox) bone marrow transplanted into Ldlr(-/-) mice. Compared with control Ldlr(-/-) chimeric mice, CD11c-Cre × Tcf4(-/flox) mice had reduced atherosclerosis levels. To begin to understand the mechanisms by which pDCs regulate atherosclerosis, we studied chimeric Ldlr(-/-) mice with selective MHCII deficiency on pDCs. Significantly, these mice also developed reduced atherosclerosis compared with controls without reductions in pDC numbers or changes in conventional DCs. MHCII-deficient pDCs showed defective stimulation of apolipoprotein B100-specific CD4(+) T cells in response to native low-density lipoprotein, whereas production of interferon-α was not affected. Finally, the atheroprotective effect of selective MHCII deficiency in pDCs was associated with significant reductions of proatherogenic T cell-derived interferon-γ and lesional T cell infiltration, and was abrogated in CD4(+) T cell-depleted animals. CONCLUSIONS: This study supports a proatherogenic role for pDCs in murine atherosclerosis and identifies a critical role for MHCII-restricted antigen presentation by pDCs in driving proatherogenic T cell immunity.
Assuntos
Células Apresentadoras de Antígenos/imunologia , Aterosclerose/imunologia , Aterosclerose/patologia , Linfócitos T CD4-Positivos/imunologia , Células Dendríticas/imunologia , Antígenos de Histocompatibilidade Classe II/imunologia , Imunidade Adaptativa/imunologia , Animais , Aorta/citologia , Linfócitos B/citologia , Linfócitos B/imunologia , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/genética , Fatores de Transcrição de Zíper de Leucina e Hélice-Alça-Hélix Básicos/imunologia , Linfócitos T CD4-Positivos/citologia , Comunicação Celular/imunologia , Células Cultivadas , Células Dendríticas/citologia , Citometria de Fluxo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores de LDL/genética , Receptores de LDL/imunologia , Fator de Transcrição 4RESUMO
BACKGROUND: Vascular aneurysm is an abnormal local dilatation of an artery that can lead to vessel rupture and sudden death. The only treatment involves surgical or endovascular repair or exclusion. There is currently no approved medical therapy for this condition. Recent data established a strong association between genetic variants in the 9p21 chromosomal region in humans and the presence of cardiovascular diseases, including aneurysms. However, the mechanisms linking this 9p21 DNA variant to cardiovascular risk are still unknown. METHODS AND RESULTS: Here, we show that deletion of the orthologous 70-kb noncoding interval on mouse chromosome 4 (chr4(Δ70kb/Δ70kb) mice) is associated with reduced aortic expression of cyclin-dependent kinase inhibitor genes p19Arf and p15Inkb. Vascular smooth muscle cells from chr4(Δ70kb/Δ70kb) mice show reduced transforming growth factor-ß-dependent canonical Smad2 signaling but increased cyclin-dependent kinase-dependent Smad2 phosphorylation at linker sites, a phenotype previously associated with tumor growth and consistent with the mechanistic link between reduced canonical transforming growth factor-ß signaling and susceptibility to vascular diseases. We also show that targeted deletion of the 9p21 risk interval promotes susceptibility to aneurysm development and rupture when mice are subjected to a validated model of aneurysm formation. The vascular disease of chr4(Δ70kb/Δ70kb) mice is prevented by treatment with a cyclin-dependent kinase inhibitor. CONCLUSIONS: The results establish a direct mechanistic link between 9p21 noncoding risk interval and susceptibility to aneurysm and may have important implications for the understanding and treatment of vascular diseases.
Assuntos
Aneurisma/patologia , Cromossomos/genética , Proteína Smad2/metabolismo , Aneurisma/tratamento farmacológico , Aneurisma/mortalidade , Animais , Células Cultivadas , Cromossomos/metabolismo , Inibidor de Quinase Dependente de Ciclina p15/deficiência , Inibidor de Quinase Dependente de Ciclina p15/genética , Inibidor de Quinase Dependente de Ciclina p19/deficiência , Inibidor de Quinase Dependente de Ciclina p19/genética , Modelos Animais de Doenças , Suscetibilidade a Doenças , Flavonoides/farmacologia , Flavonoides/uso terapêutico , Expressão Gênica/efeitos dos fármacos , Estimativa de Kaplan-Meier , Metaloproteinase 12 da Matriz/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Músculo Liso Vascular/citologia , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Fenótipo , Fosforilação/efeitos dos fármacos , Piperidinas/farmacologia , Piperidinas/uso terapêutico , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Fatores de Risco , Transdução de Sinais/efeitos dos fármacos , Fator de Crescimento Transformador beta/farmacologiaRESUMO
Chronic inflammation in response to lipoprotein accumulation in the arterial wall is central in the development of atherosclerosis. Both innate and adaptive immunity are involved in this process. Adaptive immune responses develop against an array of potential antigens presented to effector T lymphocytes by antigen-presenting cells, especially dendritic cells. Functional analysis of the role of different T-cell subsets identified the Th1 responses as proatherogenic, whereas regulatory T-cell responses exert antiatherogenic activities. The effect of Th2 and Th17 responses is still debated. Atherosclerosis is also associated with B-cell activation. Recent evidence established that conventional B-2 cells promote atherosclerosis. In contrast, innate B-1 B cells offer protection through secretion of natural IgM antibodies. This review discusses the recent development in our understanding of the role of T- and B-cell subsets in atherosclerosis and addresses the role of dendritic cell subpopulations in the control of adaptive immunity.