NOTCH1 Mutations in Aortic Stenosis: Association with Osteoprotegerin/RANK/RANKL

Background. The NOTCH pathway is known to be important in the pathogenesis of calcific aortic valve disease, possibly through regulators of osteoprotegerin (OPG), receptor activator of nuclear factor κB (RANK), and its ligand (RANKL) system. The purpose of the present study was to search for possible associations between NOTCH1 gene mutations and circulating levels of OPG and soluble RANKL (sRANKL) in patients with aortic stenosis (AS). Methods. The study was performed on 61 patients with AS including 31 with bicuspid and 30 with tricuspid aortic valves. We applied a strategy of targeted mutation screening for 10 out of 34 exons of the NOTCH1 gene by direct sequencing. Serum OPG and sRANKL levels were assessed. Results. In total, 6 genetic variants of the NOTCH1 gene including two new mutations were identified in the study group. In an age- and arterial hypertension-adjusted multivariable regression analysis, the serum OPG levels and the OPG/sRANKL ratio were correlated with NOTCH1 missense variants. All studied missense variants in NOTCH1 gene were found in Ca(2+)-binding EGF motif of the NOTCH extracellular domain bound to Delta-like 4. Conclusion. Our results suggest that the OPG/RANKL/RANK system might be directly influenced by genetic variants of NOTCH1 in aortic valve calcification

¹⁸F-sodium fluoride and ¹⁸F-fluorodeoxyglucose positron emission tomography for assessment of aortic valve inflammation and calcification in patients with aortic stenosis

Aim. To determine the inflammation and calcification activity in aortic stenosis (AS) by assessing the accumulation of 18F-FDG and 18F-NaF in the aortic valve; to study the relationship of the AS severity, aortic calcification and the accumulation of 18F-FDG and 18F-NaF. Material and methods. The study included 62 patients with asymptomatic AS (29 patients with tricuspid (TAV) and 33 with bicuspid (BAV) aortic valve), aged 40 to 70 years. The maximum flow rate at the aortic valve (Vmax) differs from 2,4 m/s to 4,5 m/s. The mean age of patients was 59,44±7,33 years, M:W 1:1. Patients with infective endocarditis and chronic rheumatic heart disease were excluded. The AS severity was assessed according to the standard protocol of transthoracic echocardiography with the use of Vivid 7 ultrasound system (GE,USA). All patients underwent combined positron emission tomography/computed tomography (PET/CT) of the aortic valve using the Discovery 710 system. Evaluation of calcification and inflammation activity of the aortic valve was performed using 8F-NaF and 18F-FDG PET/CT. A quantitative assessment of radiopharmaceuticals accumulation was carried out using uptake ratio indices. The calcium score was calculated using SmartScore 4.0 software.Results. Patients with TAV and BAV were comparable in severity of AS, the median Vmax was 2,9 [2,6; 3,4] m/s and 2,9 [2,3; 3,3] m/s, respectively. Also, TAV and BAV patients did not differ in calcification values (Agatston score 1088 [465; 2192] and 1128 [442; 2391] HU, respectively). The association of 18F-FDG accumulation and AS severity has not been established. At the same time, the association was found between the aortic valve peak velocity and the calcium score (r=0,57, p< 0,0001), as well as the 18F-NaF accumulation values — maximum, mean and maximum to mean (r=0,37, p=0,002; r=0,46, p=0,0001 and r=0,41, p=0,0008, respectively). No association between the accumulation of 18F-FDG and 18F-NaF (r=0,098, p=0,49) was found.Conclusion. It was found that the inflammation according to 18F-FDG PET/CT does not play a significant role in AS pathogenesis. At this time, 18F-NaF PET/CT is a reliable method for the AS diagnosis and valve calcification assessment. It can be used to evaluate the prognosis and effectiveness of therapy in TAV and BAV patients

THE ROLE OF OSTEOPROTEGERIN SYSTEM /RANKL/RANK IN PATHOGENESIS OF AORTIC STENOSIS

Aim. To assess the concentrations of osteoprotegerin (OPG) and soluble ligand of the receptor of transcription activator factor kappa-B (sRANKL) in the blood serum of patients with various grade of aortic stenosis (AS) severity.Material and methods. Totally, 247 AS patients studied of various grade: 46 — mild, 53 — moderate and 149 — severe. Of those 132 (53%) with bicuspid aortic valve (BAV) and 115 (47%) with tricuspid (TAV). Controls were 58 patients with no valvular pathology or coronary heart disease. All patients underwent lipid profile measurement, serum C-reactive protein (CRP) and OPG, sRANKL.Results. In all studied groups of AS patients there was increased level of sRANKL in blood serum, comparing to controls (BAV =0,37 [0,32;0,53] pM/L, TAV =0,38 [0,33;0,50] pM/L, controls 0,30 [0,21;0,39] pM/L; р<0,0001). Concentration of OPG was increased only in TAV: 6,99 [5,19;9,90] pM/L; comparing to 5,23 [4,30;7,09] pM/L in BAV (р=0,0008). A hypothesis proposed that OPG concentration increase is compensatory and takes place as a response to the increase of the concentration or due to loss of sensitivity to sRANKL.Conclusion. Development of AS is related to disorders in OPG/RANKL system, and these revealed changes might have significant diagnostic and predictive value, especially in TAV

Detection rate and clinical significance of latent infective endocarditis in patients with aortic stenosis

Aim.  To assess the  detection  rate  of infective endocarditis  (IE) in postoperative period in patients with aortic stenosis  (AS) and analyze the impact of late diagnosis on disease outcomes.Material and methods. A retrospective analysis of the register of 1764 patients with AS, formed on the basis  of transthoracic echocardiographic (echo)  tests  in2009-2011, was performed. During the 8-year follow-up period, 679 patients were operated  on;  IE  was  diagnosed  in  131  people.  Patients  were  divided  into subgroups depending  on the  valve morphology  and  the  time of IE verification before   or  after  surgery.   IE, first  detected  in  the  postoperative  period,  was considered as latent IE.Results. Among patients  with AS, the proportion of people  with IE was only 3,7%, however, pathomorphological examination revealed  IE signs in 19,3%. In 58,8% ofcases, IE was detected for the first time in the postoperative period. In 66,2% of cases,latent IE was diagnosed in patients with congenital heart disease (CHD) — bicuspidaortic valve (BAV). In the group of patients with known IE before surgery, there were lower levels of hemoglobin, erythrocytes and a higher level of creatinine. According to the results of a histological examination, inactive IE was diagnosed in 28% of cases. In 26,5% of patients  stage  3 activity IE was defined,  among  which latent course  was recorded in 16%. Single-agent antibiotic therapy (ABT) was carried out in 40,5% of patients, dual-agent ABT — in 50,0%, triple-agent — in 9,5%. The median duration of ABT was 14 days (7 to 42). The eight-year survival rate for patients with IE was 91,2%. Of the 9 deaths, only 5 (56%) had a diagnosis of IE before surgery.Conclusion. More than half of the patients operated on for AV defects  had a latent course  of IE and,  as  a  result,  late  diagnosis,  which could  affect  medium-term survival. Most of the people  with latent IE included in the analysis had CHD-BAV, which requires the development of IE preventive measures in this patient population. Various  approaches to  the  ABT of latent  IE in clinical practice   determine  the relevance  of additional  studies  aimed  at unification the  ABT approaches in this clinical setting

Different Notch signaling in cells from calcified bicuspid and tricuspid aortic valves

Aims: Calcific aortic valve disease is the most common heart valve disease in the Western world. Bicuspid and tricuspid aortic valve calcifications are traditionally considered together although the dynamics of the disease progression is different between the two groups of patients. Notch signaling is critical for bicuspid valve development and NOTCH] mutations are associated with bicuspid valve and calcification. We hypothesized that Notch-dependent mechanisms of valve mineralization might be different in the two groups.Methods and results: We used aortic valve interstitial cells and valve endothelial cells from patients with calcific aortic stenosis with bicuspid or tricuspid aortic valve. Expression of Notch-related genes in valve interstitial cells by qPCR was different between bicuspid and tricuspid groups. Discriminant analysis of gene expression pattern in the interstitial cells revealed that the cells from calcified bicuspid valves formed a separate group from calcified tricuspid and control cells. Interstitial cells from bicuspid calcified valves demonstrated significantly higher sensitivity to stimuli at early stages of induced proosteogenic differentiation and were significantly more sensitive to the activation of proosteogenic OPN, ALP and POSTIN expression by Notch activation. Notch-activated endothelial-to-mesenchymal transition and the corresponding expression of HEY1 and SLUG were also more prominent in bicuspid valve derived endothelial cells compared to the cells from calcified tricuspid and healthy valves.Conclusion: Early signaling events including Notch-dependent mechanisms that are responsible for the initiation of aortic valve calcification are different between the patients with bicuspid and tricuspid aortic valves

БЕЛКОВЫЕ МАРКЕРЫ ОБНОВЛЕНИЯ И ГИБЕЛИ МИТОХОНДРИЙ У ПАЦИЕНТОВ С НАРУШЕНИЕМ КРОВООБРАЩЕНИЯ

Patients with abnormal left ventricular outflow tract had middle lactic acidemia with detected cytochrome C release into the bloodstream and liberation of protein PGC1a (peroxisome proliferator-activated receptor gamma coactivator-1alpha) with elevation its blood concentration reflecting mitochondrial biogenesis in tissues.У пациентов с патологией выходного тракта левого желудочка в условиях развивающейся лактоацидемии обнаружен выход в кровоток цитохрома С и повышение в крови концентрации белка PGC1a (1альфа-коактиватор гамма-рецептора, активирующего пролиферацию пе-роксисом), регулирующего биогенез митохондрий