RESUMO
RATIONALE: Macrophages face a substantial amount of cholesterol after the ingestion of apoptotic cells, and the LIPA (lysosomal acid lipase) has a major role in hydrolyzing cholesteryl esters in the endocytic compartment. OBJECTIVE: Here, we directly investigated the role of LIPA-mediated clearance of apoptotic cells both in vitro and in vivo. METHODS AND RESULTS: We show that LIPA inhibition causes a defective efferocytic response because of impaired generation of 25-hydroxycholesterol and 27-hydroxycholesterol. Reduced synthesis of 25-hydroxycholesterol after LIPA inhibition contributed to defective mitochondria-associated membrane leading to mitochondrial oxidative stress-induced NLRP3 (NOD-like receptor family, pyrin domain containing) inflammasome activation and caspase-1-dependent Rac1 (Ras-related C3 botulinum toxin substrate 1) degradation. A secondary event consisting of failure to appropriately activate liver X receptor-mediated pathways led to mitigation of cholesterol efflux and apoptotic cell clearance. In mice, LIPA inhibition caused defective clearance of apoptotic lymphocytes and stressed erythrocytes by hepatic and splenic macrophages, culminating in splenomegaly and splenic iron accumulation under hypercholesterolemia. CONCLUSIONS: Our findings position lysosomal cholesterol hydrolysis as a critical process that prevents metabolic inflammation by enabling efficient macrophage apoptotic cell clearance.
Assuntos
Colesterol/metabolismo , Inflamação/metabolismo , Lisossomos/metabolismo , Macrófagos/metabolismo , Oxisteróis/metabolismo , Esterol Esterase/metabolismo , Animais , Apoptose , Transporte Biológico , Ésteres do Colesterol/metabolismo , Eritrócitos/metabolismo , Hidrólise , Hipercolesterolemia/metabolismo , Inflamassomos/metabolismo , Receptores X do Fígado/metabolismo , Linfócitos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Neuropeptídeos/metabolismo , Receptores de LDL/metabolismo , Esplenomegalia/metabolismo , Esterol Esterase/antagonistas & inibidores , Proteínas rac1 de Ligação ao GTP/metabolismoRESUMO
BACKGROUND: Lecithin:cholesterol acyltransferase (LCAT) is the sole enzyme that esterifies cholesterol in plasma. Its role in the supposed protection from atherogenesis remains unclear because mutations in LCAT causing fish-eye disease (FED) or familial LCAT deficiency (FLD) have been reported to be associated with more or instead less carotid atherosclerosis, respectively. This discrepancy may be associated with the loss of cholesterol esterification on only apolipoprotein AI (FED) or on both apolipoprotein AI- and apolipoprotein B-containing lipoproteins (FLD), an aspect that has thus far not been investigated. METHODS: Seventy-four heterozygotes for LCAT mutations recruited from Italy and the Netherlands were assigned to FLD (n=33) or FED (n=41) groups and compared with 280 control subjects. Subclinical atherosclerosis was assessed with carotid intima-media thickness. RESULTS: Compared with control subjects, total cholesterol was lower by 16% (-32.9 mg/dL) and 7% (-14.9 mg/dL) and high-density lipoprotein cholesterol was lower by 29% (-16.7 mg/dL) and 36% (-20.7 mg/dL) in the FLD and FED groups, respectively. Subjects with FLD displayed a significant 18% lower low-density lipoprotein cholesterol compared with subjects with FED (101.9±35.0 versus 123.6±47.4 mg/dL; P=0.047) and control subjects (122.6±35.0 mg/dL; P=0.003). Remarkably, all 3 intima-media thickness parameters were lower in subjects with FLD compared with FED and control subjects (accounting for age, sex, body mass index, smoking, hypertension, family history of cardiovascular disease, and plasma lipids). After additional correction for nationality and ultrasonographic methods, average and maximum intima-media thickness remained significantly lower when subjects with FLD were compared with those with FED (0.59 versus 0.73 mm, P=0.003; and 0.87 versus 1.24 mm, P<0.001, respectively). In contrast, the common carotid intima-media thickness (corrected for age, sex, body mass index, smoking, hypertension, family history of cardiovascular disease, and plasma lipids) was higher in subjects with FED compared with control subjects (0.69 versus 0.65 mm; P=0.05), but this significance was lost after adjustment for nationality and ultrasonographic machine. CONCLUSIONS: In this head-to-head comparison, FLD and FED mutations were shown to be associated with decreased and increased atherosclerosis, respectively. We propose that this discrepancy is related to the capacity of LCAT to generate cholesterol esters on apolipoprotein B-containing lipoproteins. Although this capacity is lost in FLD, it is unaffected in FED. These results are important when considering LCAT as a target to decrease atherosclerosis.
Assuntos
Doenças das Artérias Carótidas/etiologia , Deficiência da Lecitina Colesterol Aciltransferase/genética , Mutação , Fosfatidilcolina-Esterol O-Aciltransferase/genética , Adulto , Doenças das Artérias Carótidas/diagnóstico por imagem , Espessura Intima-Media Carotídea , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Feminino , Marcadores Genéticos , Predisposição Genética para Doença , Heterozigoto , Homozigoto , Humanos , Itália , Deficiência da Lecitina Colesterol Aciltransferase/complicações , Deficiência da Lecitina Colesterol Aciltransferase/diagnóstico , Deficiência da Lecitina Colesterol Aciltransferase/enzimologia , Masculino , Pessoa de Meia-Idade , Países Baixos , Fenótipo , Fosfatidilcolina-Esterol O-Aciltransferase/metabolismo , Medição de Risco , Fatores de RiscoRESUMO
BACKGROUND: The CANTOS trial (Canakinumab Antiinflammatory Thrombosis Outcome Study) showed that antagonism of interleukin (IL)-1ß reduces coronary heart disease in patients with a previous myocardial infarction and evidence of systemic inflammation, indicating that pathways required for IL-1ß secretion increase cardiovascular risk. IL-1ß and IL-18 are produced via the NLRP3 inflammasome in myeloid cells in response to cholesterol accumulation, but mechanisms linking NLRP3 inflammasome activation to atherogenesis are unclear. The cholesterol transporters ATP binding cassette A1 and G1 (ABCA1/G1) mediate cholesterol efflux to high-density lipoprotein, and Abca1/g1 deficiency in myeloid cells leads to cholesterol accumulation. METHODS: To interrogate mechanisms connecting inflammasome activation with atherogenesis, we used mice with myeloid Abca1/g1 deficiency and concomitant deficiency of the inflammasome components Nlrp3 or Caspase-1/11. Bone marrow from these mice was transplanted into Ldlr-/- recipients, which were fed a Western-type diet. RESULTS: Myeloid Abca1/g1 deficiency increased plasma IL-18 levels in Ldlr-/- mice and induced IL-1ß and IL-18 secretion in splenocytes, which was reversed by Nlrp3 or Caspase-1/11 deficiency, indicating activation of the NLRP3 inflammasome. Nlrp3 or Caspase-1/11 deficiency decreased atherosclerotic lesion size in myeloid Abca1/g1-deficient Ldlr-/- mice. Myeloid Abca1/g1 deficiency enhanced caspase-1 cleavage not only in splenic monocytes and macrophages, but also in neutrophils, and dramatically enhanced neutrophil accumulation and neutrophil extracellular trap formation in atherosclerotic plaques, with reversal by Nlrp3 or Caspase-1/11 deficiency, suggesting that inflammasome activation promotes neutrophil recruitment and neutrophil extracellular trap formation in atherosclerotic plaques. These effects appeared to be indirectly mediated by systemic inflammation leading to activation and accumulation of neutrophils in plaques. Myeloid Abca1/g1 deficiency also activated the noncanonical inflammasome, causing increased susceptibility to lipopolysaccharide-induced mortality. Patients with Tangier disease, who carry loss-of-function mutations in ABCA1 and have increased myeloid cholesterol content, showed a marked increase in plasma IL-1ß and IL-18 levels. CONCLUSIONS: Cholesterol accumulation in myeloid cells activates the NLRP3 inflammasome, which enhances neutrophil accumulation and neutrophil extracellular trap formation in atherosclerotic plaques. Patients with Tangier disease, who have increased myeloid cholesterol content, showed markers of inflammasome activation, suggesting human relevance.
Assuntos
Transportador 1 de Cassete de Ligação de ATP/metabolismo , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Aterosclerose/prevenção & controle , Colesterol/metabolismo , Armadilhas Extracelulares/metabolismo , Inflamassomos/metabolismo , Inflamação/prevenção & controle , Células Mieloides/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Transportador 1 de Cassete de Ligação de ATP/deficiência , Transportador 1 de Cassete de Ligação de ATP/genética , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/deficiência , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Animais , Aterosclerose/genética , Aterosclerose/metabolismo , Aterosclerose/patologia , Estudos de Casos e Controles , Caspase 1/genética , Caspase 1/metabolismo , Caspases/genética , Caspases/metabolismo , Caspases Iniciadoras , Citocinas/sangue , Modelos Animais de Doenças , Humanos , Inflamassomos/deficiência , Inflamassomos/genética , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Camundongos Knockout , Células Mieloides/patologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/deficiência , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Placa Aterosclerótica , Receptores de LDL/genética , Receptores de LDL/metabolismo , Baço/metabolismo , Doença de Tangier/sangue , Doença de Tangier/genéticaRESUMO
OBJECTIVE: Plasma high-density lipoproteins have several putative antiatherogenic effects, including preservation of endothelial functions. This is thought to be mediated, in part, by the ability of high-density lipoproteins to promote cholesterol efflux from endothelial cells (ECs). The ATP-binding cassette transporters A1 and G1 (ABCA1 and ABCG1) interact with high-density lipoproteins to promote cholesterol efflux from ECs. To determine the impact of endothelial cholesterol efflux pathways on atherogenesis, we prepared mice with endothelium-specific knockout of Abca1 and Abcg1. APPROACH AND RESULTS: Generation of mice with EC-ABCA1 and ABCG1 deficiency required crossbreeding Abca1(fl/fl)Abcg1(fl/fl)Ldlr(-/-) mice with the Tie2Cre strain, followed by irradiation and transplantation of Abca1(fl/fl)Abcg1(fl/fl) bone marrow to abrogate the effects of macrophage ABCA1 and ABCG1 deficiency induced by Tie2Cre. After 20 to 22 weeks of Western-type diet, both single EC-Abca1 and Abcg1 deficiency increased atherosclerosis in the aortic root and whole aorta. Combined EC-Abca1/g1 deficiency caused a significant further increase in lesion area at both sites. EC-Abca1/g1 deficiency dramatically enhanced macrophage lipid accumulation in the branches of the aorta that are exposed to disturbed blood flow, decreased aortic endothelial NO synthase activity, and increased monocyte infiltration into the atherosclerotic plaque. Abca1/g1 deficiency enhanced lipopolysaccharide-induced inflammatory gene expression in mouse aortic ECs, which was recapitulated by ABCG1 deficiency in human aortic ECs. CONCLUSIONS: These studies provide direct evidence that endothelial cholesterol efflux pathways mediated by ABCA1 and ABCG1 are nonredundant and atheroprotective, reflecting preservation of endothelial NO synthase activity and suppression of endothelial inflammation, especially in regions of disturbed arterial blood flow.
Assuntos
Transportador 1 de Cassete de Ligação de ATP/deficiência , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/deficiência , Aorta Torácica/metabolismo , Doenças da Aorta/metabolismo , Aterosclerose/metabolismo , Colesterol/metabolismo , Células Endoteliais/metabolismo , Transportador 1 de Cassete de Ligação de ATP/genética , Membro 1 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/genética , Animais , Aorta Torácica/patologia , Aorta Torácica/fisiopatologia , Doenças da Aorta/genética , Doenças da Aorta/patologia , Aterosclerose/genética , Aterosclerose/patologia , Aterosclerose/fisiopatologia , Transplante de Medula Óssea , Dieta Hiperlipídica , Modelos Animais de Doenças , Progressão da Doença , Células Endoteliais/patologia , Predisposição Genética para Doença , Mediadores da Inflamação/metabolismo , Macrófagos/metabolismo , Masculino , Camundongos Knockout , Monócitos/metabolismo , Neovascularização Fisiológica , Óxido Nítrico Sintase Tipo III/metabolismo , Fenótipo , Placa Aterosclerótica , Receptores de LDL/deficiência , Receptores de LDL/genética , Fluxo Sanguíneo Regional , Neovascularização Retiniana/genética , Neovascularização Retiniana/metabolismo , Fatores de Tempo , Técnicas de Cultura de Tecidos , Irradiação Corporal TotalRESUMO
Although recent genome-wide association studies have called into question the causal relationship between high-density lipoprotein (HDL) cholesterol levels and cardiovascular disease, ongoing research in animals and cells has produced increasing evidence that cholesterol efflux pathways mediated by ATP-binding cassette (ABC) transporters and HDL suppress atherosclerosis. These differing perspectives may be reconciled by a modified HDL theory that emphasizes the antiatherogenic role of cholesterol flux pathways, initiated in cells by ABC transporters. ABCA1 and ABCG1 control the proliferation of hematopoietic stem and multipotential progenitor cells in the bone marrow and hematopoietic stem and multipotential progenitor cell mobilization and extramedullary hematopoiesis in the spleen. Thus, activation of cholesterol efflux pathways by HDL infusions or liver X receptor activation results in suppression of hematopoietic stem and multipotential progenitor cell mobilization and extramedullary hematopoiesis, leading to decreased production of monocytes and neutrophils and suppression of atherosclerosis. In addition, macrophage-specific knockout of transporters has confirmed their role in suppression of inflammatory responses in the arterial wall. Recent studies have also shown that ABCG4, a close relative of ABCG1, controls platelet production, atherosclerosis, and thrombosis. ABCG4 is highly expressed in megakaryocyte progenitors, where it promotes cholesterol efflux to HDL and controls the proliferative responses to thrombopoietin. Reconstituted HDL infusions act in an ABCG4-dependent fashion to limit hypercholesterolemia-driven excessive platelet production, thrombosis, and atherogenesis, as occurs in human myeloproliferative syndromes. Activation of ABC transporter-dependent cholesterol efflux pathways in macrophages, hematopoietic stem and multipotential progenitor cells, or platelet progenitors by reconstituted HDL infusion or liver X receptor activation remain promising approaches to the treatment of human atherothrombotic diseases.
Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Aterosclerose/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Humanos , Inflamação/metabolismo , Lipoproteínas LDL/metabolismo , Transdução de SinaisRESUMO
OBJECTIVE: We previously demonstrated that subjects with functional ATP-binding cassette (ABC) A1 mutations have increased atherosclerosis, which has been attributed to the role of ABCA1 in reverse cholesterol transport. More recently, a proinflammatory effect of Abca1 deficiency was shown in mice, potentially contributing to atherogenesis. In this study, we investigated whether ABCA1 deficiency was associated with proinflammatory changes in humans. APPROACH AND RESULTS: Thirty-one heterozygous, 5 homozygous ABCA1 mutation carriers, and 21 matched controls were studied. (18)Fluorodeoxyglucose positron emission tomography with computed tomographic scanning was performed in a subset of carriers and controls to assess arterial wall inflammation (target:background ratio). Heterozygous ABCA1 mutation carriers had a 20% higher target:background ratio than in controls (target:background ratio; P=0.008). In carriers using statins (n=7), target:background ratio was 21% reduced than in nonstatin users (n=7; P=0.03). We then measured plasma cytokine levels. Tumor necrosis factor α, monocyte chemoattractant protein-1, and interleukin-6 levels were increased in heterozygous and homozygous ABCA1 mutation carriers. We isolated monocytes from carriers and controls and measured inflammatory gene expression. Only TNFα mRNA was increased in monocytes from heterozygous ABCA1 mutation carriers. Additional studies in THP-1 macrophages showed that both ABCA1 deficiency and lipoprotein-deficient plasma from ABCA1 mutation carriers increased inflammatory gene expression. CONCLUSIONS: Our data suggest a proinflammatory state in ABCA1 mutation carriers as reflected by an increased positron emission tomography-MRI signal in nonstatin using subjects, and increased circulating cytokines. The increased inflammation in ABCA1 mutation carriers seems to be attenuated by statins.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Inflamação/genética , Mutação , Placa Aterosclerótica/genética , Apolipoproteínas B/sangue , Transporte Biológico , Colesterol/sangue , Citocinas/sangue , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Inflamação/metabolismo , Inflamação/prevenção & controle , Lipoproteínas/sangue , Macrófagos/metabolismo , Placa Aterosclerótica/metabolismo , Placa Aterosclerótica/prevenção & controleRESUMO
AIMS: Low HDL-C is a potent risk factor for cardiovascular disease (CVD). Yet, mutations in ABCA1, a major determinant of circulating HDL-C levels, were previously not associated with CVD risk in cohort studies. To study the consequences of low plasma levels of high-density lipoprotein cholesterol (HDL-C) due to ATP-binding cassette transporter A1 (ABCA1) dysfunction for atherosclerotic vascular disease in the carotid arteries. METHODS AND RESULTS: We performed 3.0 Tesla magnetic resonance imaging (MRI) measurements of the carotid arteries in 36 carriers of high impact functional ABCA1 mutations and 36 normolipidemic controls. Carriers presented with 42% lower HDL-C levels (P < 0.001), a larger mean wall area (18.6 ± 6.0 vs. 15.8 ± 4.3 mm(2); P = 0.02), a larger mean wall thickness (0.82 ± 0.21 vs. 0.70 ± 0.14 mm; P = 0.005), and a higher normalized wall index (0.37 ± 0.06 vs. 0.33 ± 0.04; P = 0.005) compared with controls, retaining significance after adjustment for smoking, alcohol consumption, systolic blood pressure, diabetes, body mass index, history of CVD, LDL-C, and statin use (P = 0.002). CONCLUSION: Carriers of loss of function ABCA1 mutations display a larger atherosclerotic burden compared with age and sex-matched controls, implying a higher risk for CVD. Further studies are needed to elucidate the full function of ABCA1 in the protection against atherosclerosis. These data support the development of strategies to up-regulate ABCA1 in patients with established CVD.
Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Doenças das Artérias Carótidas/genética , Artéria Carótida Primitiva , HDL-Colesterol/deficiência , Mutação/genética , Transportador 1 de Cassete de Ligação de ATP , Doenças das Artérias Carótidas/patologia , Estudos de Casos e Controles , HDL-Colesterol/genética , Feminino , Heterozigoto , Homozigoto , Humanos , Angiografia por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Placa Aterosclerótica/genética , Placa Aterosclerótica/patologiaRESUMO
Few studies have addressed the delivery of lipoprotein-derived cholesterol to the adrenals for steroid production in humans. While there is evidence against a role for low-density lipoprotein (LDL), it is unresolved whether high density lipoprotein (HDL) contributes to adrenal steroidogenesis. To study this, steroid hormone profiles in urine were assessed in male subjects suffering from functional mutations in ATP binding cassette transporter A1 (ABCA1) (n = 24), lecithin:cholesterol acyltransferase (LCAT) (n = 40), as well as in 11 subjects with low HDL cholesterol (HDL-C) without ABCA1/LCAT mutations. HDL-C levels were 39% lower in the ABCA1, LCAT, and low HDL-C groups compared with controls (all P < 0.001). In all groups with low HDL-C levels, urinary excretion of 17-ketogenic steroids was reduced by 33%, 27%, and 32% compared with controls (all P < 0.04). In seven carriers of either type of mutation, adrenocorticotropic hormone (ACTH) stimulation did not reveal differences from normolipidemic controls. In conclusion, this study shows that basal but not stimulated corticosteroid metabolism is attenuated in subjects with low HDL-C, irrespective of its molecular origin. These findings lend support to a role for HDL as a cholesterol donor for basal adrenal steroidogenesis in humans.
Assuntos
Glândulas Suprarrenais/metabolismo , HDL-Colesterol/sangue , Esteroides/biossíntese , Transportador 1 de Cassete de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Hormônio Adrenocorticotrópico/sangue , Hormônio Adrenocorticotrópico/urina , Adulto , Idoso , HDL-Colesterol/urina , Humanos , Masculino , Pessoa de Meia-Idade , Fosfatidilcolina-Esterol O-Aciltransferase/genética , Fosfatidilcolina-Esterol O-Aciltransferase/metabolismo , Esteroides/urinaRESUMO
In vitro studies have suggested that HDL and apoB-containing lipoproteins can provide cholesterol for synthesis of glucocorticoids. Here we assessed adrenal glucocorticoid function in LCAT knockout (KO) mice to determine the specific contribution of HDL-cholesteryl esters to adrenal glucocorticoid output in vivo. LCAT KO mice exhibit an 8-fold higher plasma free cholesterol-to-cholesteryl ester ratio (P < 0.001) and complete HDL-cholesteryl ester deficiency. ApoB-containing lipoprotein and associated triglyceride levels are increased in LCAT KO mice as compared with C57BL/6 control mice (44%; P < 0.05). Glucocorticoid-producing adrenocortical cells within the zona fasciculata in LCAT KO mice are devoid of neutral lipids. However, adrenal weights and basal corticosterone levels are not significantly changed in LCAT KO mice. In contrast, adrenals of LCAT KO mice show compensatory up-regulation of genes involved in cholesterol synthesis (HMG-CoA reductase; 516%; P < 0.001) and acquisition (LDL receptor; 385%; P < 0.001) and a marked 40-50% lower glucocorticoid response to adrenocorticotropic hormone exposure, endotoxemia, or fasting (P < 0.001 for all). In conclusion, our studies show that HDL-cholesteryl ester deficiency in LCAT KO mice is associated with a 40-50% lower adrenal glucocorticoid output. These findings further highlight the important novel role for HDL as cholesterol donor for the synthesis of glucocorticoids by the adrenals.
Assuntos
Glândulas Suprarrenais/metabolismo , Técnicas de Inativação de Genes , Glucocorticoides/metabolismo , Fosfatidilcolina-Esterol O-Aciltransferase/genética , Fosfatidilcolina-Esterol O-Aciltransferase/metabolismo , Animais , Ésteres do Colesterol/metabolismo , Corticosterona/metabolismo , Hepatócitos/metabolismo , Lipoproteínas HDL/metabolismo , Camundongos , Regulação para CimaRESUMO
Maintenance of the asymmetric distribution of phospholipids across the plasma membrane is a prerequisite for the survival of erythrocytes. Various stimuli have been shown to induce scrambling of phospholipids and thereby exposure of phosphatidylserine (PS). In two types of patients, both with aberrant plasma cholesterol levels, we observed an aberrant PS exposure in erythrocytes upon stimulation. We investigated the effect of high and low levels of cholesterol on the ATP-dependent flippase, which maintains phospholipid asymmetry, and the ATP-independent scrambling activity, which breaks down phospholipid asymmetry. We analyzed erythrocytes of a patient with spur cell anemia, characterized by elevated plasma cholesterol, and the erythrocytes of Tangier disease patients with very low levels of plasma cholesterol. In normal erythrocytes, loaded with cholesterol or depleted of cholesterol in vitro, the same analyses were performed. Changes in the cholesterol/phospholipid ratio of erythrocytes had marked effects on PS exposure upon cell activation. Excess cholesterol profoundly inhibited PS exposure, whereas cholesterol depletion led to increased PS exposure. The activity of the ATP-dependent flippase was not changed, suggesting a major influence of cholesterol on the outward translocation of PS. The effects of cholesterol were not accompanied by eminent changes in cytoskeletal and membrane proteins. These findings emphasize the importance of cholesterol exchange between circulating plasma and the erythrocyte membrane as determinant for phosphatidylserine exposure in erythrocytes.
Assuntos
Colesterol/metabolismo , Membrana Eritrocítica/metabolismo , Eritrócitos/metabolismo , Fosfatidilserinas/metabolismo , 4-Cloro-7-nitrobenzofurazano/análogos & derivados , 4-Cloro-7-nitrobenzofurazano/metabolismo , Anemia Hemolítica/sangue , Proteína 1 de Troca de Ânion do Eritrócito/metabolismo , Transporte Biológico/efeitos dos fármacos , Calcimicina/farmacologia , Cálcio/metabolismo , Ionóforos de Cálcio/farmacologia , Colesterol/farmacologia , Eletroforese em Gel de Poliacrilamida , Membrana Eritrocítica/química , Eritrócitos/citologia , Eritrócitos/efeitos dos fármacos , Humanos , Fosfatidilcolinas/metabolismo , Fosfolipídeos/metabolismo , Espectrina/metabolismo , Doença de Tangier/sangue , Fatores de TempoRESUMO
Prospective epidemiological studies have consistently reported an inverse association between HDL cholesterol (HDL-C) levels and the risk of cardiovascular disease (CVD). However, large intervention trials on HDL-C-increasing drugs and recent Mendelian randomization studies have questioned a causal relationship between HDL-C and atherosclerosis. HDL-C levels have been shown to be highly heritable, and the combination of HDL-C-associated SNPs in recent large-scale genome-wide association studies (GWAS) only explains a small proportion of this heritability. As a large part of our current understanding of HDL metabolism comes from genetic studies, further insights in this research field may aid us in elucidating HDL functionality in relation to CVD risk. In this review we focus on the question of whether genetically defined HDL-C levels are associated with risk of atherosclerosis. We also discuss the latest insights for HDL-C-associated genes and recent GWAS data.
Assuntos
Aterosclerose/genética , HDL-Colesterol/genética , Aterosclerose/metabolismo , HDL-Colesterol/metabolismo , Predisposição Genética para Doença , Humanos , Polimorfismo de Nucleotídeo Único , Fatores de RiscoRESUMO
Early detection of colorectal cancer (CRC) is currently based on fecal occult blood testing (FOBT) and colonoscopy, both which can significantly reduce CRC-related mortality. However, FOBT has low-sensitivity and specificity, whereas colonoscopy is labor- and cost-intensive. Therefore, the discovery of novel biomarkers that can be used for improved CRC screening, diagnosis, staging and as targets for novel therapies is of utmost importance. To identify novel CRC biomarkers we utilized representational difference analysis (RDA) and characterized a colon cancer associated transcript (CCAT1), demonstrating consistently strong expression in adenocarcinoma of the colon, while being largely undetectable in normal human tissues (p < 000.1). CCAT1 levels in CRC are on average 235-fold higher than those found in normal mucosa. Importantly, CCAT1 is strongly expressed in tissues representing the early phase of tumorigenesis: in adenomatous polyps and in tumor-proximal colonic epithelium, as well as in later stages of the disease (liver metastasis, for example). In CRC-associated lymph nodes, CCAT1 overexpression is detectable in all H&E positive, and 40.0% of H&E and immunohistochemistry negative lymph nodes, suggesting very high sensitivity. CCAT1 is also overexpressed in 40.0% of peripheral blood samples of patients with CRC but not in healthy controls. CCAT1 is therefore a highly specific and readily detectable marker for CRC and tumor-associated tissues.
Assuntos
Biomarcadores Tumorais/genética , Neoplasias do Colo/genética , Precursores de RNA/genética , RNA Neoplásico/biossíntese , Adenocarcinoma/diagnóstico , Adenocarcinoma/genética , Pólipos Adenomatosos/diagnóstico , Pólipos Adenomatosos/genética , Adolescente , Sequência de Aminoácidos , Sequência de Bases , Biomarcadores Tumorais/análise , Linhagem Celular Tumoral , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Neoplasias do Colo/diagnóstico , Neoplasias do Colo/patologia , Detecção Precoce de Câncer/métodos , Células HCT116 , Células HT29 , Humanos , Mucosa Intestinal/metabolismo , Linfonodos/metabolismo , Dados de Sequência Molecular , Mucosa/metabolismo , Metástase Neoplásica , Precursores de RNA/análise , RNA Neoplásico/genética , Sensibilidade e Especificidade , Regulação para CimaRESUMO
PURPOSE OF REVIEW: To review published data related to the potential applicability of apolipoprotein A-I mimetic peptides. RECENT FINDINGS: Despite a wealth of information on HDL-C levels and risk for cardiovascular disease (CVD), little evidence is present to suggest that raising HDL-C levels per se will result in CVD risk reduction. Rather, increasing HDL functionality might be a more successful strategy to reverse the process of atherosclerosis. In as such, apoA-I mimetic peptides, either in single or tandem formulation, hold great promise. Evidence gathered over the last years has provided insight in the extent to which mimetics influence several cardio metabolic pathways. ApoA-I mimetics have shown to have anti-inflammatory, antioxidant, and antiatherogenic effects. Direct comparisons between different mimetics have provided insight in factors influencing the differential beneficial consequences of these peptides. Data derived from recent studies suggest that mimetics might gain their position as a therapeutic intervention in the treatment of septicaemia, transplantation rejection, diabetes and auto-immune diseases. SUMMARY: This review provides a summary of the current literature on the potential application of apoA-I mimetics as therapeutic agents. There is increasing evidence that these mimetics should be considered as a promising supplement to current strategies. Results from human studies addressing the in-vivo effects of the different apoA-I mimetics are eagerly awaited.
Assuntos
Anti-Inflamatórios , Apolipoproteína A-I , Aterosclerose/tratamento farmacológico , Biomimética , Doenças Cardiovasculares/tratamento farmacológico , Peptídeos , Animais , Anti-Inflamatórios/síntese química , Anti-Inflamatórios/metabolismo , Anti-Inflamatórios/uso terapêutico , Apolipoproteína A-I/síntese química , Apolipoproteína A-I/metabolismo , Apolipoproteína A-I/uso terapêutico , Aterosclerose/metabolismo , Aterosclerose/prevenção & controle , Doenças Cardiovasculares/metabolismo , Doenças Cardiovasculares/prevenção & controle , Química Farmacêutica , HDL-Colesterol/metabolismo , Ensaios Clínicos Controlados como Assunto , Humanos , Camundongos , Peptídeos/síntese química , Peptídeos/metabolismo , Peptídeos/uso terapêutico , Ratos , Fatores de RiscoRESUMO
BACKGROUND: The contribution of apolipoprotein A-I (apoA-I) to coronary heart disease (CHD) risk stratification over and above high-density lipoprotein cholesterol (HDL-C) is unclear. We studied the associations between plasma levels of HDL-C and apoA-I, either alone or combined, with risk of CHD events and cardiovascular risk factors among apparently healthy men and women. METHODS AND RESULTS: HDL-C and apoA-I levels were measured among 17 661 participants of the EPIC (European Prospective Investigation into Cancer)-Norfolk prospective population study. Hazard ratios for CHD events and distributions of risk factors were calculated by quartiles of HDL-C and apoA-I. Results were validated using data from the ARIC (Atherosclerosis Risk in Communities) and WHS (Women's Health Study) cohorts, comprising 15 494 and 27 552 individuals, respectively. In EPIC-Norfolk, both HDL-C and apoA-I quartiles were strongly and inversely associated with CHD risk. Within HDL-C quartiles, higher apoA-I levels were not associated with lower CHD risk; in fact, CHD risk was higher within some HDL-C quartiles. ApoA-I levels were associated with higher levels of CHD risk factors: higher body mass index, HbA1c, non-HDL-C, triglycerides, apolipoprotein B, systolic blood pressure, and C-reactive protein, within fixed HDL-C quartiles. In contrast, HDL-C levels were consistently inversely associated with overall CHD risk and CHD risk factors within apoA-I quartiles (P<0.001). These findings were validated in the ARIC and WHS cohorts. CONCLUSIONS: Our findings demonstrate that apoA-I levels do not offer predictive information over and above HDL-C. In fact, within some HDL-C quartiles, higher apoA-I levels were associated with higher risk of CHD events, possibly because of the unexpected higher prevalence of cardiovascular risk factors in association with higher apoA-I levels. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00000479.
Assuntos
Apolipoproteína A-I/metabolismo , HDL-Colesterol/metabolismo , Doença das Coronárias/metabolismo , Saúde da Mulher , Idoso , Antineoplásicos/administração & dosagem , Aspirina/administração & dosagem , Doenças Cardiovasculares/prevenção & controle , Doença das Coronárias/mortalidade , Método Duplo-Cego , Inglaterra/epidemiologia , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Pessoa de Meia-Idade , Neoplasias/prevenção & controle , Inibidores da Agregação Plaquetária/administração & dosagem , Prognóstico , Estudos Prospectivos , Fatores de Risco , Vitamina E/administração & dosagemRESUMO
In this report, we present a patient who suffered from a myocardial infarction at an extremely young age. The only remarkable finding in the risk factor workup was a near undetectable high-density lipoprotein (HDL)-cholesterol plasma level (0.09 mmol/L). Genetic analysis of key genes involved in HDL metabolism resulted in the discovery of 2 very rare mutations in the ABCA1 and APOA1 genes. We discuss the effects of these mutations on HDL metabolism and reverse cholesterol transport and interpret these findings in relation to the extensive atherosclerosis at a very young age in this patient.
Assuntos
Transportador 1 de Cassete de Ligação de ATP/deficiência , Apolipoproteína A-I/deficiência , Lipoproteínas HDL/metabolismo , Mutação , Infarto do Miocárdio/genética , Infarto do Miocárdio/metabolismo , Adulto , Humanos , MasculinoRESUMO
INTRODUCTION: Adrenal steroidogenesis is essential for human survival and depends on the availability of the precursor cholesterol. Male subjects with low plasma levels of high density lipoprotein (HDL) cholesterol are characterized by decreased adrenal function. Whether this is also the case in female subjects with low plasma HDL-C levels is unresolved to date. FINDINGS: 15 female ATP binding cassette transporter AI (ABCAI) and 14 female lecithin-cholesterol acyltransferase (LCAT) were included in the study. HDL-C levels were 38% and 41% lower in ABCA1 and LCAT mutation carriers compared to controls, respectively. Urinary steroid excretion of 17-ketogenic steroids or 17-hydroxy corticosteroids did not differ between 15 female ABCA1 mutation carriers (p = 0.27 vs 0.30 respectively) and 30 matched normolipidemic controls or between 14 female LCAT mutation carriers and 28 matched normolipidemic controls (p = 0.10 and 0.14, respectively). Cosyntropin testing in an unselected subgroup of 8 ABCA1 mutation carriers and 3 LCAT mutation carriers did not reveal differences between carriers and controls. CONCLUSION: Adrenal function in females with molecularly defined low HDL-C levels is not different from controls. The discrepancy with the finding of impaired steroidogenesis in males with molecularly defined low HDL-C levels underscores the importance of gender specific analyses in cholesterol-related research.
Assuntos
Transportador 1 de Cassete de Ligação de ATP/genética , Glândulas Suprarrenais/metabolismo , HDL-Colesterol/metabolismo , Fosfatidilcolina-Esterol O-Aciltransferase/metabolismo , 17-Cetosteroides/metabolismo , Adulto , Feminino , Humanos , Pessoa de Meia-Idade , Mutação/genética , Fosfatidilcolina-Esterol O-Aciltransferase/genéticaRESUMO
BACKGROUND: Macrophages are crucial cells in the pathogenesis of atherosclerosis. Macrophages are plastic cells which can switch from a classical pro-inflammatory M1 to an alternative anti-inflammatory M2 macrophage phenotype, depending on the environmental stimuli. Because high-density lipoprotein (HDL) cholesterol levels are inversely correlated to cardiovascular disease and since HDL displays anti-inflammatory properties, we investigated whether HDL can affect alternative macrophage differentiation of primary human monocytes in the presence of interleukin (IL)-4, a M2 macrophage polarization driver, in vitro and ex vivo. METHODS AND RESULTS: M2 macrophages are highly responsive to HDL stimulation, since the expression of pentraxin 3 (PTX3), a well known HDL target gene, is induced by HDL more strongly in M2 macrophages than in control unpolarized resting macrophages (RM). As expected, the expression of M2 markers, such as Mannose Receptor (MR), CD200 Receptor (CD200R), Coagulation factor XIII A1 (F13A1), IL-1 receptor antagonist (IL-1RA) and IL10, was induced in IL-4 polarized M2 macrophages compared to RM. However, incubation with HDL added in vitro did not modulate the gene expression of M2 macrophage polarization markers. Moreover, monocytes isolated from subjects with genetically low HDL levels, carrying ABCA1 or LCAT mutations, differentiated ex vivo into M2 macrophages without any difference in the alternative macrophage marker expression profile. CONCLUSIONS: These in vitro and ex vivo results indicate that, contrary to mouse macrophages, HDL does not influence macrophage M2 polarization of human monocyte-derived macrophages. Thus, the anti-inflammatory properties of HDL in humans are probably not related to the enhancement of the M2 macrophage phenotype.
Assuntos
Aterosclerose/imunologia , Polaridade Celular/imunologia , HDL-Colesterol/imunologia , Inflamação/imunologia , Monócitos/imunologia , Transportador 1 de Cassete de Ligação de ATP/genética , Transportador 1 de Cassete de Ligação de ATP/imunologia , Adulto , Antígenos de Superfície/genética , Antígenos de Superfície/imunologia , Aterosclerose/genética , Aterosclerose/patologia , Biomarcadores , Células Cultivadas , HDL-Colesterol/farmacologia , Fator XIII/genética , Fator XIII/imunologia , Feminino , Expressão Gênica/imunologia , Humanos , Inflamação/genética , Inflamação/patologia , Lectinas Tipo C/genética , Lectinas Tipo C/imunologia , Masculino , Receptor de Manose , Lectinas de Ligação a Manose/genética , Lectinas de Ligação a Manose/imunologia , Pessoa de Meia-Idade , Monócitos/efeitos dos fármacos , Monócitos/patologia , Receptores de Orexina , Fenótipo , Fosfatidilcolina-Esterol O-Aciltransferase/genética , Fosfatidilcolina-Esterol O-Aciltransferase/imunologia , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/imunologia , Adulto JovemRESUMO
PURPOSE: Mutations in apolipoprotein A-I (apoA-I) may affect plasma high-density lipoprotein (HDL) cholesterol levels and the risk for cardiovascular disease but little is known about the presence and effects of circulating apoA-I variants. This study investigates whether the apoA-I mutations, apoA-I(L202P) and apoA-I(K131del) , are present on plasma HDL particles derived from heterozygote carriers and whether this is associated to changes in HDL protein composition. EXPERIMENTAL DESIGN: Plasma HDL of heterozygotes for either apoA-I(L202P) or apoA-I(K131del) and family controls was isolated using ultracentrifugation. HDL proteins were separated by 2DE and analyzed by MS. RESULTS: ApoA-I peptides containing apoA-I(L202P) or apoA-I(K131del) were identified in HDL from heterozygotes. The apoA-I(L202P) mutant peptide was less abundant than wild-type peptide while the apoA-I(K131del) mutant peptide was more abundant than wild-type peptide in the heterozygotes. Two-dimensional gel electrophoresis analyses indicated that, compared to controls, HDL in apoA-I(L202P) carriers contained less apoE and more zinc-α-2-glycoprotein while HDL from the apoA-I(K131del) heterozygotes contained more alpha-1-antitrypsin and transthyretin. CONCLUSIONS AND CLINICAL RELEVANCE: Both apoA-I(L202P) and apoA-I(K131del) were identified in HDL. In heterozygotes, these mutations have markedly differential effects on the concentration of wild-type apoA-I in the circulation, as well as the HDL proteome, both of which might affect the clinical phenotype encountered in the heterozygous carriers.