Fetuin is the key for nanon self-propagation

Calciprotein Particle Synthesis Strategy Determines In Vitro Calcification Potential

Circulating calciprotein particles (CPP), colloids of calcium, phosphate and proteins, were identified as potential drivers of the calcification process in chronic kidney disease. The present study compared CPP produced using different protocols with respect to particle morphology, composition, particle number and in vitro calcification potency. CPP were synthesized with 4.4 mM (CPP-A and B) or 6 mM (CPP-C and D) phosphate and 2.8 mM (CPP-A and B) or 10 mM (CPP-C and D) calcium, with either bovine fetuin-A (CPP-C) or fetal bovine serum (CPP-A, B and D) as a source of protein, and incubated for 7 (CPP-A2) or 14 days (CPP-B2), 12 h (CPP-C2, D2 and B1) or 30 min (CPP-D1). Particle number was determined with nanoparticle tracking and calcium content was measured in CPP preparations and to determine human vascular smooth muscle cell (hVSMC) calcification. Morphologically, CPP-C2 were the largest. Particle number did not correspond to the calcium content of CPP. Both methods of quantification resulted in variable potencies of CPP2 to calcify VSMC, with CPP-B2 as most stable inducer of hVSMC calcification. In contrast, CPP-B1 and D1 were unable to induce calcification of hVSMC, and endogenous CPP derived from pooled serum of dialysis patients were only able to calcify hVSMC to a small extent compared to CPP2.CPP synthesized using different protocols appear morphologically similar, but in vitro calcification potency is dependent on composition and how the CPP are quantified. Synthetic CPP are not comparable to endogenous CPP in terms of the calcification propensity.

Clinical implications of fetuin-A

Fetuin-A, also termed alpha2-Heremans-Schmid glycoprotein, is a 46kDa hepatocyte derived protein (hepatokine) and serves multifaceted functions.

Calcifying nanoparticles induce cytotoxicity mediated by ROS-JNK signaling pathways

Calcifying nanoparticles (CNPs) play an important role in kidney stone formation, but the mechanism(s) are unclear. CNPs were isolated and cultured from midstream urine of patients with kidney stones. CNP morphology and characteristics were examined by electron microscopy and electrophoresis analysis. Chemical composition was analyzed using energy-dispersive X-ray microanalysis and Western blotting. Human renal proximal convoluted tubule cell (HK-2) cultures were exposed to CNPs for 0, 12 and 72 h, and production of reactive oxygen species (ROS), mitochondrial membrane potential and apoptosis levels were evaluated. CNPs isolated from patients showed classical morphology, the size range of CNPs were 15-500 nm and negative charge; they were found to contain fetuin-A. Exposure of HK-2 cells to CNPs induced ROS production, decreased mitochondrial membrane potential and decreased cell viability. Transmission electron microscopy showed that CNPs can enter the cell by phagocytosis, and micrographs revealed signs of apoptosis and autophagy. CNPs increased the proportion of apoptotic cells, down-regulated Bcl-2 expression and up-regulated Bax expression. CNPs also up-regulated expression of LC3-B, Beclin-1and p-JNK.CNPs are phagocytosed by HK-2 cells, leading to autophagy, apoptosis and ROS production, in part through activation of JNK signaling pathways. ROS and JNK pathways may contribute to CNP-induced cell injury and kidney stone formation.

Cholesterol gallstones and bile host diverse bacterial communities with potential to promote the formation of gallstones

The prevalence of cholesterol gallstones has increased in recent years. Bacterial infection correlates with the formation of gallstones. We studied the composition and function of bacterial communities in cholesterol gallstones and bile from 22 cholesterol gallstone patients using culture-dependent and culture-independent methods. Altogether fourteen and eight bacterial genera were detected in cholesterol gallstones and bile, respectively. Pseudomonas spp. were the dominant bacteria in both cholesterol gallstones and bile. As judged by diversity indices, hierarchical clustering and principal component analysis, the bacterial communities in gallstones were different from those in bile. The gallstone microbiome was considered more stable than that of bile. The different microbial communities may be partially explained by differences in their habitats. We found that 30% of the culturable strains from cholesterol gallstones secreted β-glucuronidase and phospholipase A2. Pseudomonas aeruginosa strains showed the highest β-glucuronidase activity and produced the highest concentration of phospholipase A2, indicating that Ps. aeruginosa may be a major agent in the formation of cholesterol gallstones.