Poster No. 118 TheIL6rs1800795polymorphism is associated with ascending thoracic aortic dilatation in bicuspid aortic valve patients

Antecedentes

Los pacientes con válvula aórtica bicúspide (BAV), en comparación con las personas con válvula aórtica tricúspide normal, tienen un mayor riesgo de desarrollar dilatación de la aorta ascendente (DAA). La disfunción valvular significativa no explica una complicación aórtica desafortunada y, por lo tanto, los mecanismos moleculares involucrados se encuentran bajo investigación. Uno de los procesos involucrados es la inflamación y las citocinas como la interleucina-6 están asociados con las dimensiones aórticas y con la degeneración de la matriz extracelular aórtica en modelos animales. . Por este motivo, nos propusimos analizar un polimorfismo del gen de la interleucina-6 (IL6), que regula positivamente la transcripción y traducción del gen, en pacientes con VAB.

Material y métodos

Presentamos una serie de 119 pacientes con VAB genotipados para el polimorfismo rs1800795 en la región promotora del gen IL6 . Se realizaron modelos de regresión logística multivariable.

Resultados y conclusiones

Nuestros pacientes, todos con VAB, tenían una mediana de edad de 55 años, 76,5% hombres, 29,4% fumadores, 30% dislipidémicos, 35,3% hipertensos, 12,6% diabéticos y 44% con DAA de 39 a 49 mm. Homocigotos El genotipo para el alelo C del polimorfismo IL6 fue significativamente menos frecuente en pacientes con dilatación (OR = 0,32, IC del 95% = 0,11–0,96, P = 0,035). Tras ajustar por variables de confusión como sexo, edad, hipertensión arterial y valvulopatía, los pacientes portadores del genotipo CC seguían teniendo menor probabilidad de padecer DAA (OR = 0,25; IC95% = 0,07–0,76; P = 0,02).

La identificación de individuos con predisposición genética para el desarrollo de DAA es fundamental en beneficio de un seguimiento médico más estrecho. Son necesarios más estudios para evaluar su uso en la aortopatía bicúspide.

Investigación financiada por la Sociedad Española de Cardiología; ISCIII-PI1800694; Fundación-Asturcor;Programa Severo-Ochoa.

IL6 gene polymorphism association with calcific aortic valve stenosis and influence on serum levels of interleukin-6

Aortic valve stenosis is the most frequent valve disease in developed countries and its prevalence will increase with population aging. There is still no pharmaceutical treatment nor biomarker to determine the susceptibility to develop aortic stenosis. Therefore, we analyzed the association of polymorphisms in risk loci with calcific aortic stenosis. Patients with aortic valve disease were genotyped for PALMD rs6702619, LPA rs10455872, and IL6 rs1800795 polymorphisms and circulating levels of interleukin-6 (IL-6) were measured. Calcium content of leaflets obtained in valve replacement surgeries was determined by micro-computed tomography. In the genotyping of 578 individuals, we found significant association between PALMD and IL6 polymorphisms and aortic stenosis in patients with tricuspid aortic valve, independently of other potentially confounding variables such as age and dyslipidemia. There was no association of these polymorphisms with valve calcium content, but this value correlated with the mean aortic pressure gradient (r = 0.44; P < 0.001). The CC genotype of IL6 polymorphism was associated with higher levels of serum IL-6 compared to other genotypes (23.5 vs. 10.5 pg/ml, respectively; P = 0.029). Therefore, patients carrying the CC genotype of IL6 rs1800795 polymorphism present higher levels of circulating IL-6 and this could contribute to the severity of the aortic valve stenosis. Our results agree with the identification of IL6 as a locus risk for stenosis and also with the intervention of this cytokine in aortic valve calcification. A more exhaustive follow-up of those patients carrying risk genotypes is therefore recommended.

Bicuspid aortic valve: what should I know? Updated review of its clinical and pathophysiological aspects

La válvula aórtica bicúspide es la cardiopatía congénita más frecuente en la población general. Lejos de ser solo una malformación valvular inocua, supone una enfermedad compleja y heterogénea. A menudo es identificada como un hallazgo incidental en personas sanas, cursando de manera asintomática. Sin embargo, en un alto porcentaje de pacientes conduce a lo largo de su vida a complicaciones valvulares (estenosis, insuficiencia, endocarditis) o aórticas (dilatación o disección). Con frecuencia estas manifestaciones suceden a una edad temprana y causan una elevada morbimortalidad. A pesar de que en los últimos años se ha producido una intensa investigación en este campo, la fisiopatogenia de la enfermedad no es del todo conocida y muchas preguntas siguen abiertas. En este artículo se revisan de forma actualizada los aspectos clínicos y fisiopatológicos más novedosos y relevantes sobre esta cardiopatía congénita.

The most common congenital heart disease in the general population is the bicuspid aortic valve. Far from being just a harmless valve malformation, it is a complex and heterogeneous disease. It is often identified as an incidental finding in healthy people. However, in a high percentage of patients it leads throughout their life towards valvular (stenosis, insufficiency, endocarditis) or aortic (dilatation or dissection) complications. Frequently, manifestations occur at an early age, being responsible for high morbidity and mortality. Even though in recent years intense research has been carried out in this field, the pathophysiogenesis of the disease is not fully known and many questions remain open. In this article, we review the most innovative and relevant clinical and pathophysiological aspects of this congenital heart disease.

CYP24A1 and KL polymorphisms are associated with the extent of vascular calcification but do not improve prediction of cardiovascular events

Background

Novel ways of determining cardiovascular risk are needed as a consequence of population ageing and the increased prevalence of chronic kidney disease (CKD), both of which favour vascular calcification. Since the formation of arterial calcium deposits has a genetic component, single nucleotide polymorphisms (SNPs) could predict cardiovascular events.

Methods

A selection of 1927 CKD patients and controls recruited by the NEFRONA study were genotyped for 60 SNPs from 22 candidate genes. A calcium score was calculated from the echogenicity of arterial atherosclerotic plaques and the presence of cardiovascular events during a 4-year period was recorded. Association of SNPs with the calcium score was identified by multiple linear regression models and their capacity to predict events was assessed by means of Cox proportional hazards regression and receiver operating characteristics curves.

Results

Two variants, rs2296241 of CYP24A1 and rs495392 of KL, were associated with the calcium score. Despite this, only heterozygotes for rs495392 had a lower risk of suffering an event compared with homozygotes for the major allele {hazard ratio (HR) 0.67 [95% confidence interval (CI) 0.48−0.93]}. Of note, the calcium score was associated with an increased risk of cardiovascular events [HR 1.71 (95% CI 1.35−2.17)]. The addition of the rs495392 genotype to classical cardiovascular risk factors did not increase the predictive power [area under the curve (AUC) 71.3 (95% CI 61.1−85.5) versus 71.4 (61.5−81.4)].

Conclusions

Polymorphisms of CYP24A1 and KL are associated with the extent of calcification but do not predict cardiovascular events. However, the echogenic determination of the extent of calcium deposits seems a promising non-irradiating method for the scoring of calcification in high-risk populations.

MO036SINGLE NUCLEOTIDE POLYMORPHISMS OF THE CYP24A1 AND KL GENES ARE ASSOCIATED WITH THE EXTENT OF ARTERIAL CALCIFICATION IN PATIENTS WITH CHRONIC KIDNEY DISEASE

Background and Aims

Individuals with chronic kidney disease (CKD) constitute a population with an exceptionally high cardiovascular risk. Vascular calcification, a common finding in these patients, is a known contributor to cardiovascular disease and several studies suggest it has a certain genetic component. Single nucleotide polymorphisms (SNPs) associated with the extent of calcification in CKD patients could therefore be used to predict individual susceptibility to calcification and subsequent increased cardiovascular risk. We consequently searched for associations of SNPs from candidate genes of known implication in the pathogenesis of vascular calcification (encoding cytokines, extracellular matrix proteins, members of the RANK/RANKL/OPG axis and vitamin D metabolism proteins) with the extent of arterial calcium deposits in order to improve the risk prediction of cardiovascular events in CKD patients.

Method

The study was performed in 1439 individuals from the NEFRONA population, which include CKD patients (stages 2-3, 4-5, and dialysis) as well as healthy controls recruited from 81 Spanish hospitals. Individuals were genotyped with the iPLEXGOLD MassARRAY technology and Assay Design v4 software for 61 SNPs from 22 genes. A continuous vascular calcification score was calculated from the echogenicity of atherosclerotic plaques detected by ultrasonography in the carotid and femoral arteries. Among several other clinical variables, the presence of cardiovascular events during a 4-year follow up was collected. Association of SNPs with calcification extent was identified by univariate linear regression models. Multiple linear regression with backward elimination was used for the selection of an appropriate SNP-based model adjusted by age, sex and CKD stages. Finally, a Cox proportional hazard regression model was applied for the prediction of cardiovascular risk.

Results

Arterial calcification scores were higher with increasing age, male sex, and advanced CKD stages (all p&lt;0.001), as expected. Univariate linear regression analyses of all SNPs with the arterial calcification score as dependent variable retrieved p-values &lt;0.05 for 6 six of them (rs11568820, rs2248359, rs2296241, rs3102735, rs385564 and rs495392), which were selected for subsequent analyses. These polymorphisms were next included in a multivariate linear regression model with CKD stage, age and sex as additional independent variables. Only rs2296241 of CYP24A1 (estimate 0.36, 95% CI 0.14 to 0.58, p=0.001 for homocygous GG) and rs495392 of KL (estimate -0.39, 95% CI -0.69 to -0.09, p=0.011 for homocygous TT) remained independently associated with the extent of calcium deposits. Finally, using Cox regression models, it was determined that both the CKD stage (HR [for dialysis stage]=8.34, 95% CI 4.59 to 15.15, p&lt;0.001) and the calcification score (HR=2.05, 95% CI 1.67 to 2.54, p&lt;0.001) predicted the development of cardiovascular events. Considering all possible risk factors, no differences were found in the rate of development of cardiovascular events according to the genotype for the two associated polymorphisms: rs2296241 HR=1.13, 95% CI 0.87 to 1.48, p=0.36; rs495392 HR=0.80 95% CI 0.63 to 1.03, p=0.08.

Conclusions

Polymorphisms of KL and CYP24A1 genes are associated with the extent of calcification in CKD individuals although they lack the capacity to predict cardiovascular events. However, the echogenic determination of the extent of arterial calcium deposits in CKD patients seems a promising non-invasive, non-irradiating method for the scoring of calcification and even the prediction of cardiovascular events. Further genetic association studies using this technique could therefore yield valuable results.

Correlation of Micro-Computed Tomography Assessment of Valvular Mineralisation with Histopathological and Immunohistochemical Features of Calcific Aortic Valve Disease

Aortic valve stenosis is a serious disease with increasing prevalence in developed countries. Research aimed at uncovering the molecular mechanisms behind its main cause, aortic valve calcification, is thus crucial for the development of future therapies. It is frequently difficult to measure the extent of mineralisation in soft tissues and some methods require the destruction of the sample. Micro-computed tomography (µCT), a non-destructive technique, was used to quantify the density and volume of calcium deposits on cusps from 57 explanted aortic valves. Conventional and immunostaining techniques were used to characterise valve tissue degeneration and the inflammatory and osteogenic stage with several markers. Although most of the analysed cusps came from severe stenosis patients, the µCT parameter bone volume/tissue volume ratio distinguished several degrees of mineralisation that correlated with the degree of structural change in the tissue and the amount of macrophage infiltration as determined by CD68 immunohistochemistry. Interestingly, exosomal markers CD63 and Alix co-localised with macrophage infiltration surrounding calcium deposits, suggesting that those vesicles could be produced at least in part by these immune cells. In conclusion, we have shown that the ex vivo assessment of aortic valve mineralisation with µCT reflects the molecular and cellular changes in pathological valves during progression towards stenosis. Thus, our results give additional validity to quantitative μCT as a convenient laboratory tool for basic research on this type of cardiovascular calcification.

Regulation of miR-29b and miR-30c by vitamin D receptor activators contributes to attenuate uraemia-induced cardiac fibrosis

Background

Uraemic cardiomyopathy, a process mainly associated with increased myocardial fibrosis, is the leading cause of death in chronic kidney disease patients and can be prevented by vitamin D receptor activators (VDRAs). Since some microRNAs (miRNAs) have emerged as regulators of the fibrotic process, we aimed to analyse the role of specific miRNAs in VDRA prevention of myocardial fibrosis as well as their potential use as biomarkers.

Methods

Wistar rats were nephrectomized and treated intraperitoneally with equivalent doses of two VDRAs: calcitriol and paricalcitol. Biochemical parameters, cardiac fibrosis, miRNA (miR-29b, miR-30c and miR-133b) levels in the heart and serum and expression of their target genes collagen I (COL1A1), matrix metalloproteinase 2 (MMP-2) and connective tissue growth factor (CTGF) in the heart were evaluated.

Results

Both VDRAs attenuated cardiac fibrosis, achieving a statistically significant difference in the paricalcitol-treated group. Increases in RNA and protein levels of COL1A1, MMP-2 and CTGF and reduced expression of miR-29b and miR-30c, known regulators of these pro-fibrotic genes, were observed in the heart of chronic renal failure (CRF) rats and were attenuated by both VDRAs. In serum, significant increases in miR-29b, miR-30c and miR-133b levels were observed in CRF rats, which were prevented by VDRA use. Moreover, vitamin D response elements were identified in the three miRNA promoters.

Conclusions

VDRAs, particularly paricalcitol, attenuated cardiac fibrosis acting on COL1A1, MMP-2 and CTGF expression, partly through regulation of miR-29b and miR-30c. These miRNAs and miR-133b could be useful serum biomarkers for cardiac fibrosis and also potential new therapeutic targets.