The Relationship between Serum Sclerostin Levels and Bone Mineral Disorders and Vascular Calcification in Hemodialysis Patients

Background and aim of the study: Sclerostin is produced by osteocytes and has been shown to down-regulate the synthesis of many markers of bone formation by osteogenic cells. The aim of this study to investigate the relationship between serum sclerostin levels and bone mineral disorders and vascular calcification in hemodialysis patients (HD). Methods:This is a cross-sectional study of 70 patients with ESRD on regular HD for at least six months, Theodor Bilharz Research Institute, Giza, Egypt.Twenty-five subjects who matched the ages, genders, and demographics of the study patients were included as a control group.All patients and control groups included in the study underwent a full through history and clinical examination. Serum calcium, phosphorus, alkaline phosphatase and intact PTH (iPTH) levels were measured. Serum sclerostin was measured by an ELISA. Bone Mineral Densitometry Measurements BMD (g/cm2) was determined by dual-energy X-ray absorptiometry (DXA). CT scan was done to detect the presence or absence of vascular calcification and transthoracic echocardiogram to detect the presence or absence of valvular calcification. Results:The mean seumscleostin levels was a statistically significant high in the HD patients when compared with the control group (156.8 ±121.4 Vs.29.38±0.84, p =0.0001 ) and statistically significant high mean ALP in the HD patients when compared with the control group (147.2 ± 94.3 Vs. 38.8 ±23.4, p = 0.0001). The mean BMD was statistically significant low in the HD patients when compared with the controls (0.839±0.086 g/ m2 Vs.1.306 ±0.153 g/ m2, p = 0.0001).The mean seumscleostin levels was statistically significant high in the HD patients with vascular and valvular calcification when compared with HD patients without calcification.Using spearman correlation coefficient analysis, there was statistically significant negative correlations between serum sclerostin levels and iPTH(r=-0.362, p =0.0021), ALP (r=-0.301, p =0.0114), and BMD (r=-0.469, p =0.0278 ), and there was a statistically significant positive correlation between serum sclerostin levels and phosphate(r=0.5829, p =0.0001 ).Independent predictors of BMD in HD patients were determined using multi-variate regression analysis. Sclerostin levels, iPTH, ALP, and age were found to be independent predictors of BMD. Conclusion: High sclerostin levels in patients with ESRD on HD were associated with high risk of vascular and valvularcalcification and were independent predictors of low BMD in such population.

Vitamin K2—a neglected player in cardiovascular health: a narrative review

Vitamin K2 serves an important role in cardiovascular health through regulation of calcium homeostasis. Its effects on the cardiovascular system are mediated through activation of the anti-calcific protein known as matrix Gla protein. In its inactive form, this protein is associated with various markers of cardiovascular disease including increased arterial stiffness, vascular and valvular calcification, insulin resistance and heart failure indices which ultimately increase cardiovascular mortality. Supplementation of vitamin K2 has been strongly associated with improved cardiovascular outcomes through its modification of systemic calcification and arterial stiffness. Although its direct effects on delaying the progression of vascular and valvular calcification is currently the subject of multiple randomised clinical trials, prior reports suggest potential improved survival among cardiac patients with vitamin K2 supplementation. Strengthened by its affordability and Food and Drug Adminstration (FDA)-proven safety, vitamin K2 supplementation is a viable and promising option to improve cardiovascular outcomes.

Non-valvular Atrial Fibrillation in CKD: Role of Vitamin K Antagonists and Direct Oral Anticoagulants. A Narrative Review

Atrial fibrillation (AF) is the most common arrhythmia in chronic kidney disease (CKD), with a close bidirectional relationship between the two entities. The presence of CKD in AF increases the risk of thromboembolic events, mortality and bleeding. Vitamin K antagonists (VKA) have been the mainstay of treatment for the prevention of thromboembolic events in AF until recently, with confirmed benefits in AF patients with stage 3 CKD. However, the risk-benefit profile of VKA in patients with AF and stages 4–5 CKD is controversial due to the lack of evidence from randomized controlled trials. Treatment with VKA in CKD patients has been associated with conditions such as poorer anticoagulation quality, increased risk of bleeding, faster progression of vascular/valvular calcification and higher risk of calciphylaxis. Direct oral anticoagulants (DOACs) have shown equal or greater efficacy in stroke/systemic embolism prevention, and a better safety profile than VKA in post-hoc analysis of the pivotal randomized controlled trials in patients with non-valvular AF and stage 3 CKD, yet evidence of its risk-benefit profile in more advanced stages of CKD is scarce. Observational studies associate DOACs with a good safety/effectiveness profile compared to VKA in non-dialysis CKD patients. Further, DOACs have been associated with a lower risk of acute kidney injury and CKD development/progression than VKA. This narrative review summarizes the evidence of the efficacy and safety of warfarin and DOACs in patients with AF at different CKD stages, as well as their effects on renal function, vascular/valvular calcification and bone health.

Regular Dietary Intake of Palmitate Causes Vascular and Valvular Calcification in a Rabbit Model

Aims: Palmitic acid (PA) and oleic acid (OA) are two main dietary fatty acids. Dietary intake of PA has been associated with cardiovascular disease risk, and the effect of OA remains uncertain. Our study aimed to assess the effect of a short-term intake of lard, as source of PA and OA, on aorta and aortic valve.Methods and Results: Rabbits were fed with two lard-enriched diets, containing either elevated levels of PA or of both PA and OA as compared to chow diet. After 16 weeks of each diet, calcification was observed in the aortic intima and in the aortic valve. The extent of calcification did not differ between the two diets. In contrast, rabbits fed chow diet did not develop any calcification. In blood, PA enrichment resulted in decreased lymphocyte and monocyte counts and increased levels of hemoglobin and haematocrit. Levels of the calcification inhibitor fetuin-A were also diminished, whereas creatinine levels were raised. Of note, none of the diets changed cholesterol levels in LDL or HDL. Comprehensive quantitative lipidomics analysis identified diet-related changes in plasma lipids. Dietary PA enrichment led to a drop of polyunsaturated fatty acids (PUFA), in particular of linoleic acid in cholesteryl esters, triglycerides and diacylglycerols (DAG). Ratios of PA to 18-carbon PUFA in DAG were positively correlated with the extent of aortic valve calcification, and inversely with monocyte counts. PA content in blood correlated with aorta calcification.Conclusions: Regular dietary PA intake induces vascular and valvular calcification independently of traditional risk factors. Our findings raise awareness about PA-rich food consumption and its potential deleterious effect on cardiovascular health.

MO761THE CONTRIBUTION OF HIGH-PHOSPHORUS IN EXTRACELLULAR MATRIX ACCUMULATION OF VALVULAR CALCIFICATION IN CHRONIC KIDNEY DISEASE

Background and Aims The characteristics of valvular calcification (VC) in early stage are extracellular matrix (ECM) accumulation and muti-cells activation. In our previous work, we found high-phosphorus (HP) diet aggravated ECM accumulation in both aortic valve and mitral valve in rats with chronic kidney disease (CKD). However, the underlying mechanism of HP contribution in ECM accumulation of CKD-induced VC is still unknown. Method canine valvular interstitial cells (VICs), valvular endothelial cells (VECs) and human umbilical vein endothelial cells (HUVECs) were used in this study. CKD mice (C57b and Tek-EGFP-PolyA) was build by 0.2% adenine-diet for 6 weeks and HP diet/NP diet for 10 weeks. Results As for VICs, HP induced qVICs transfer into aVICs, not oVICs, which was characterized with upregulated level of smoothelin and viemitin. There was no calcium accumulation was observed, suggesting that VICs do not have the ability to synthesize calcium crystals under pure HP intervention. As for VECs, aVICs activated by HP induced VECs EndMT in a transwell-assay, which was characterized with decreasing protein levels of endothelial markers (CD31, vWF, VE-cadherin) and increasing protein levels of mesenchymal makers (α-SMA, FSP1, N-cadherin). Then, IL-8 was found as the main factor releasing from VICs to induce VECs EndMT. In vitro, the concentration of IL-8 in the lower chamber could reach 2-4ng/ml. Reparixin was used to inhibit IL-8 receptor of VECs, which could relive aVICs-induced EndMT. In vivo, the expression of valve CXCL-2 (the mouse IL8 functional homolog) was increased in HP-diet compared with NP-diet, though the serum level of CXCL-2 was similar between two groups. AAV9-sm22a-CXCL-2 and Reparixin could inhibit VECs EndMT by inhibiting VICs relasing CXCL-2 and inhibiting VECs IL-8 receptor in CKD mice of Tek-EGFP-PolyA respectively. Then, IL-8 was found to induced VECs EndMT by miR-214-3p/PTEN/Akt pathway. Inhibiting EndMT by blocking IL-8/miR-214-3p could alleviate ECM accumulation. Conclusion HP could induce qVICs transfer into aVICs, and aVICs could cause VECs EndMT via IL-8/miR-214-3p/PTEN/Akt pathway. Both take part in ECM accumulation in CKD-induced VC.