RESUMEN
Endogenous agonists of the transcription factor aryl hydrocarbon receptor (AHR) such as the indolic uremic toxin, indoxyl sulfate (IS), accumulate in patients with chronic kidney disease. AHR activation by indolic toxins has prothrombotic effects on the endothelium, especially via tissue factor (TF) induction. In contrast, physiological AHR activation by laminar shear stress (SS) is atheroprotective. We studied the activation of AHR and the regulation of TF by IS in cultured human umbilical vein endothelial cells subjected to laminar fluid SS (5 dynes/cm2). SS and IS markedly increased the expression of AHR target genes PTGS2 (encoding for COX2), AHRR, CYP1A1, and CYP1B1, as well as F3 (encoding for TF), in an AHR-dependent way. IS amplified SS-induced TF mRNA and protein expression and upregulation of AHR target genes. Interestingly, tyrosine kinase inhibition by genistein decreased SS- but not IS-induced TF expression. Finally, the increase in TF expression induced by laminar SS was not associated with increased TF activity. In contrast, IS increased TF activity, even under antithrombotic SS conditions. In conclusion, IS and SS induce AHR activation and AHR-dependent TF upregulation by different mechanisms. Impairment of the antithrombotic properties of shear stressed endothelium by toxic AHR agonists could favor cardiovascular diseases in CKD.
Asunto(s)
Células Endoteliales de la Vena Umbilical Humana/metabolismo , Indicán/agonistas , Indicán/toxicidad , Receptores de Hidrocarburo de Aril/efectos de los fármacos , Receptores de Hidrocarburo de Aril/metabolismo , Tromboplastina/efectos de los fármacos , Tromboplastina/metabolismo , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico , Ciclooxigenasa 2/genética , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP1B1/genética , Regulación de la Expresión Génica , Técnicas de Silenciamiento del Gen , Humanos , ARN Mensajero/metabolismo , Insuficiencia Renal Crónica/metabolismo , Estrés MecánicoRESUMEN
Chronic kidney disease (CKD) is associated with high risk of thrombosis. Indole-3 acetic acid (IAA), an indolic uremic toxin, induces the expression of tissue factor (TF) in human umbilical vein endothelial cells (HUVEC) via the transcription factor aryl hydrocarbon receptor (AhR). This study aimed to understand the signaling pathways involved in AhR-mediated TF induction by IAA. We incubated human endothelial cells with IAA at 50 µM, the maximal concentration found in patients with CKD. IAA induced TF expression in different types of human endothelial cells: umbilical vein (HUVEC), aortic (HAoEC), and cardiac-derived microvascular (HMVEC-C). Using AhR inhibition and chromatin immunoprecipitation experiments, we showed that TF induction by IAA in HUVEC was controlled by AhR and that AhR did not bind to the TF promoter. The analysis of TF promoter activity using luciferase reporter plasmids showed that the NF-κB site was essential in TF induction by IAA. In addition, TF induction by IAA was drastically decreased by an inhibitor of the NF-κB pathway. IAA induced the nuclear translocation of NF-κB p50 subunit, which was decreased by AhR and p38MAPK inhibition. Finally, in a cohort of 92 CKD patients on hemodialysis, circulating TF was independently related to serum IAA in multivariate analysis. In conclusion, TF up-regulation by IAA in human endothelial cells involves a non-genomic AhR/p38 MAPK/NF-κB pathway. The understanding of signal transduction pathways related to AhR thrombotic/inflammatory pathway is of interest to find therapeutic targets to reduce TF expression and thrombotic risk in patients with CKD.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Células Endoteliales de la Vena Umbilical Humana/efectos de los fármacos , Ácidos Indolacéticos/toxicidad , FN-kappa B/metabolismo , Receptores de Hidrocarburo de Aril/metabolismo , Transducción de Señal , Tromboplastina/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Células Cultivadas , Femenino , Técnicas de Silenciamiento del Gen , Humanos , Masculino , Persona de Mediana Edad , Regiones Promotoras Genéticas , Estudios Prospectivos , ARN Interferente Pequeño , Receptores de Hidrocarburo de Aril/genética , Insuficiencia Renal Crónica , Adulto JovenRESUMEN
Patients with chronic kidney disease (CKD) are exposed to uremic toxins and have an increased risk of cardiovascular disease. Some uremic toxins, like indoxyl sulfate, are agonists of the transcription factor aryl hydrocarbon receptor (AHR). These toxins induce a vascular procoagulant phenotype. Here we investigated AHR activation in patients with CKD and in a murine model of CKD. We performed a prospective study in 116 patients with CKD stage 3 to 5D and measured the AHR-Activating Potential of serum by bioassay. Compared to sera from healthy controls, sera from CKD patients displayed a strong AHR-Activating Potential; strongly correlated with eGFR and with the indoxyl sulfate concentration. The expression of the AHR target genes Cyp1A1 and AHRR was up-regulated in whole blood from patients with CKD. Survival analyses revealed that cardiovascular events were more frequent in CKD patients with an AHR-Activating Potential above the median. In mice with 5/6 nephrectomy, there was an increased serum AHR-Activating Potential, and an induction of Cyp1a1 mRNA in the aorta and heart, absent in AhR-/- CKD mice. After serial indoxyl sulfate injections, we observed an increase in serum AHR-AP and in expression of Cyp1a1 mRNA in aorta and heart in WT mice, but not in AhR-/- mice. Thus, the AHR pathway is activated both in patients and mice with CKD. Hence, AHR activation could be a key mechanism involved in the deleterious cardiovascular effects observed in CKD.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/sangre , Receptores de Hidrocarburo de Aril/sangre , Insuficiencia Renal Crónica/sangre , Adulto , Anciano , Anciano de 80 o más Años , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/agonistas , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/deficiencia , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Enfermedades Cardiovasculares/sangre , Enfermedades Cardiovasculares/mortalidad , Estudios de Casos y Controles , Causas de Muerte , Línea Celular Tumoral , Citocromo P-450 CYP1A1/genética , Citocromo P-450 CYP1A1/metabolismo , Modelos Animales de Enfermedad , Femenino , Humanos , Indicán/administración & dosificación , Indicán/sangre , Masculino , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Noqueados , Persona de Mediana Edad , Estudios Prospectivos , Receptores de Hidrocarburo de Aril/agonistas , Receptores de Hidrocarburo de Aril/deficiencia , Receptores de Hidrocarburo de Aril/genética , Diálisis Renal , Insuficiencia Renal Crónica/diagnóstico , Insuficiencia Renal Crónica/mortalidad , Insuficiencia Renal Crónica/terapia , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Factores de Riesgo , Resultado del TratamientoRESUMEN
Patients with chronic kidney disease (CKD) display an elevated risk of thrombosis. Thrombosis occurs in cardiovascular events, such as venous thromboembolism, stroke, and acute coronary syndrome, and is a cause of hemodialysis vascular access dysfunction. CKD leads to the accumulation of uremic toxins, which exerts toxic effects on blood and the vessel wall. Some uremic toxins result from tryptophan metabolization in the gut through the indolic and the kynurenine pathways. An increasing number of studies are highlighting the link between such uremic toxins and thrombosis in CKD. In this review, we describe the thrombotic mechanisms induced by tryptophan-derived uremic toxins (TDUT). These mechanisms include an increase in plasma levels of procoagulant factors, induction of platelet hyperactivity, induction of endothelial dysfunction/ impairment of endothelial healing, decrease in nitric oxide (NO) bioavailability, and production of procoagulant microparticles. We focus on one important prothrombotic mechanism: The induction of tissue factor (TF), the initiator of the extrinsic pathway of the blood coagulation. This induction occurs via a new pathway, dependent on the transcription factor Aryl hydrocarbon receptor (AhR), the receptor of TDUT in cells. A better understanding of the prothrombotic mechanisms of uremic toxins could help to find novel therapeutic targets to prevent thrombosis in CKD.