Asociación del polimorfismo 1G>2G de la MMP1 con calcificación de la válvula aórtica

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.

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.

Impact of several proinflammatory and cell degradation factors in patients with aortic valve stenosis

Aortic valve (AoV) stenosis is the third most common cardiovascular disease. The pathogenesis of AoV stenosis is associated with an inflammatory process where MMPs serve important roles. The aim of the present study was to determine the association between matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs) and inflammatory factors, and AoV stenosis at various degrees of severity compared with the control. A total of 18 patients with mild, 19 with moderate and 15 with severe AoV stenosis were included in the present stud, and 50 individuals were enrolled in the control group. The severity of stenosis was determined by echocardiography. The expression levels of chemerin, fibroblast growth factor 21, MMP-1, −3, and −9, and TIMP-1 and −3 were analyzed by ELISA. Data were analyzed using GraphPad Prism7 software. The expression levels of MMP-1 was increased in patients with stenosis compared with the control group (P=0.0043). Distribution of the trimodal MMP-1 values was obtained in the stenosis group and monomodal in the control group. A total of 80% of patients in the stenosis group presented significantly increased expression levels of MMP-1 compared with the control group (P=0.0002). Expression of MMP-1 was significantly higher in all stenosis groups compared with the control. The highest expression level of MMP-1 appeared in patients with moderate stenosis (P<0.0001). There was no significant difference in the expression of MMP-3, MMP-9 and TIMP-1 in the aortic stenosis group, compared with the control group. A positive correlation between MMP-1 and MMP-9 expression levels was identified (r=0.37; P=0.017). The increase of MMP-1 was correlated with the increase of MMP-9, but not with the level of MMP-3. The expression levels of chemerin was significantly elevated in patients with stenosis compared with healthy patients. The highest expression levels of chemerin were determined in patients with mild (P=0.0001) and moderate (P=0.0007) stenosis and decreased with the grade of severity compared with the control group. The expression of FGF-21 was significantly different between the control and mild (P=0.013), moderate (P=0.015) and severe stenosis (P=0.003) groups. The expression levels of FGF-21 increased with the increase in severity grade, reaching the maximum for severe stenosis. The results of the present study indicated that the inflammatory process is predominantly occurring at the early, mild stage of stenosis and the most prominent extracellular matrix remodeling occurs in moderate stenosis (demonstrated by MMP-1 levels). In patients with severe stenosis, the levels of MMP-1 and chemerin (which are lower than in a case of mild or moderate stenosis) could indicate the development of calcinosis and the reduction in activity or inactivation of the inflammatory process.