Bisphosphonate FYB-931 Prevents High Phosphate-Induced Vascular Calcification in Rat Aortic Rings by Altering the Dynamics of the Transformation of Calciprotein Particles

Patients with chronic kidney disease develop vascular calcification, owing to impaired calcium and phosphate metabolism. The prevention of vascular calcification is important to improve the prognosis of such patients. In this study, we investigated whether treatment with FYB-931, a novel bisphosphonate compound, prevents vascular calcification in rat aortic rings cultured in high-phosphate medium for 9 days, assessed by measurement of the calcium content and the degree of calcium deposition, visualized using von Kossa staining. The effect on the transformation of calciprotein particles (CPPs) from primary to secondary CPPs was assessed using a fluorescent probe-based flow cytometric assay. FYB-931 dose-dependently prevented high phosphate-induced aortic calcification, but failed to rapidly cause the regression of high phosphate-induced vascular calcification once it had developed. Furthermore, the treatment dose-dependently inhibited the high phosphate-induced transformation from primary to secondary CPPs. In addition, the treatment with FYB-931 prevented the transformation from primary to secondary CPPs in vitamin D₃-treated rats as a model of ectopic calcification, consistent with the results from rat aortic rings. In conclusion, treatment with FYB-931 prevents high phosphate-induced rat aortic vascular calcification by altering the dynamics of CPP transformation. This finding suggests that inhibition of the transformation from primary to secondary CPPs is an important target for the prevention of vascular calcification in patients with chronic kidney disease.

Citric acid-based bicarbonate dialysate attenuates aortic arch calcification in maintenance hemodialysis patients: a retrospective observational study

BACKGROUND

Progression of aortic calcification is associated with all-cause and cardiovascular mortality in hemodialysis patients. Blood calciprotein particle (CPP) levels are associated with coronary artery calcification and were reported to be inhibited when using citric acid-based bicarbonate dialysate (CD). Therefore, this study aimed to examine the effect of CD on the progression of the aortic arch calcification score (AoACS) and blood CPP levels in hemodialysis patients.

METHODS

A 12-month retrospective observational study of 262 hemodialysis patients was conducted. AoACS was evaluated by calculating the number of calcifications in 16 segments of the aortic arch on chest X-ray (minimum score is 0; maximum score is 16 points). The patients were divided into the following groups according to their baseline AoACS: grade 0, AoACS = 0 points; grade 1, AoACS 1-4 points; grade 2, AoACS 5-8 points; grade 3, AoACS 9 points or higher. Patients on bisphosphonates or warfarin or with AoACS grade 3 were excluded. Progression, defined as ΔAoACS (12-month score - baseline score) > 0 points, was compared between the CD and acetic acid-based bicarbonate dialysate (AD) groups before and after adjusting the background using propensity score matching.

RESULTS

The AoACS progression rate was significantly lower in the CD group than in the AD group (before matching: P = 0.020, after matching: P = 0.002). Multivariate logistic regression analysis showed that CD was significantly associated with AoACS progression (odds ratio 0.52, 95% confidence interval 0.29‒0.92, P = 0.025).

CONCLUSION

CD may slow the progression of vascular calcification in hemodialysis patients.

Association of circulating calciprotein particle levels with skeletal muscle mass and strength in middle-aged and older adults

Calciprotein particles (CPPs) are tiny mineral-protein aggregates consisting of calcium-phosphate and fetuin-A. Recent studies have suggested that CPPs may contribute to the pathogenesis of chronic inflammation and arteriosclerosis. Reduced skeletal muscle mass and strength reportedly contribute independently to increased serum phosphate levels. This finding suggests that reduced skeletal muscle mass and strength can endogenously induce an increase in circulating CPP levels. Therefore, we investigated the potential association between circulating CPP levels and skeletal muscle mass and strength in middle-aged and older adults. One hundred eighty-two middle-aged and older adults (age, 46-83 years) were included in this cross-sectional study (UMIN000034741). Circulating CPP levels were measured using the gel filtration method. Appendicular skeletal muscle mass was assessed using multifrequency bioelectrical impedance analysis with a tetrapolar eight-point tactile electrode system. The skeletal muscle mass index was calculated from appendicular skeletal muscle mass and height. Handgrip and knee extension strengths were used as measures of skeletal muscle strength. The skeletal muscle mass index was negatively correlated with circulating CPP levels (r = -0.31; P < 0.05). This association remained significant after adjustment for potential covariates (β = -0.34; P < 0.05). In contrast, skeletal muscle strength, represented by handgrip strength and knee extension strength, was not significantly associated with circulating CPP levels. In middle-aged and older adults, a lower skeletal muscle mass index was independently associated with higher circulating CPP levels. The present results suggest that maintaining skeletal muscle mass may prevent an increase in circulating CPP levels.