The role of calcium and nicotinic acid adenine dinucleotide phosphate (NAADP) in human osteoclast formation and resorption

Osteoclasts are specialised bone resorbing cells which form by fusion of circulating mononuclear phagocyte precursors. Bone resorption results in the release of large amounts of calcium into the extracellular fluid (ECF), but it is not certain whether changes in extracellular calcium concentration [Ca(2+)]e influence osteoclast formation and resorption. In this study, we sought to determine the effect of [Ca(2+)]e and NAADP, a potent calcium mobilising messenger that induces calcium uptake, on human osteoclast formation and resorption. CD14+ human monocytes were cultured with M-CSF and RANKL in the presence of different concentrations of calcium and NAADP and the effect on osteoclast formation and resorption evaluated. We found that the number of TRAP+ multinucleated cells and the extent of lacunar resorption were reduced when there was an increase in extracellular calcium and NAADP. This was associated with a decrease in RANK mRNA expression by CD14+ cells. At high concentrations (20 mM) of [Ca(2+)]e mature osteoclast resorption activity remained unaltered relative to control cultures. Our findings indicate that osteoclast formation is inhibited by a rise in [Ca(2+)]e and that RANK expression by mononuclear phagocyte osteoclast precursors is also [Ca(2+)]e dependent. Changes in NAADP also influence osteoclast formation, suggesting a role for this molecule in calcium handling. Osteoclasts remained capable of lacunar resorption, even at high ECF [Ca(2+)]e, in keeping with their role in physiological and pathological bone resorption.

Degesting the remodeled cardiovascular wall: role of cysteinyl cathepsins in cardiovascular disease

Cardiovascular disease (CVD) is characterized by extensive remodeling of the extracellular matrix (ECM) architecture of the cardiovascular system. Among the many extracellular proteolytic enzymes present in cardiovascular cells and inflammatory cells and involved in ECM remodeling, members of the matrix metalloproteinase family and serine protease family have received the most attention. However, recent findings from laboratory and clinical studies have indicated that lysosomal cysteinyl cathepsins also participate in pathogenesis of CVD. This review summarizes recent knowledge on discoveries regarding the relationship between cysteinly cathepsins and CVD.

Combinatorial effects of arginine and fluoride on oral bacteria

Dental caries is closely associated with the microbial disequilibrium between acidogenic/aciduric pathogens and alkali-generating commensal residents within the dental plaque. Fluoride is a widely used anticaries agent, which promotes tooth hard-tissue remineralization and suppresses bacterial activities. Recent clinical trials have shown that oral hygiene products containing both fluoride and arginine possess a greater anticaries effect compared with those containing fluoride alone, indicating synergy between fluoride and arginine in caries management. Here, we hypothesize that arginine may augment the ecological benefit of fluoride by enriching alkali-generating bacteria in the plaque biofilm and thus synergizes with fluoride in controlling dental caries. Specifically, we assessed the combinatory effects of NaF/arginine on planktonic and biofilm cultures of Streptococcus mutans, Streptococcus sanguinis, and Porphyromonas gingivalis with checkerboard microdilution assays. The optimal NaF/arginine combinations were selected, and their combinatory effects on microbial composition were further examined in single-, dual-, and 3-species biofilm using bacterial species-specific fluorescence in situ hybridization and quantitative polymerase chain reaction. We found that arginine synergized with fluoride in suppressing acidogenic S. mutans in both planktonic and biofilm cultures. In addition, the NaF/arginine combination synergistically reduced S. mutans but enriched S. sanguinis within the multispecies biofilms. More importantly, the optimal combination of NaF/arginine maintained a "streptococcal pressure" against the potential growth of oral anaerobe P. gingivalis within the alkalized biofilm. Taken together, we conclude that the combinatory application of fluoride and arginine has a potential synergistic effect in maintaining a healthy oral microbial equilibrium and thus represents a promising ecological approach to caries management.

The role of fQRS in coronary artery disease. A meta-analysis of observational studies

BACKGROUND

Experimental and clinical studies have suggested that the presence of fragmented QRS complex (fQRS) is associated with various cardiovascular diseases. fQRS may predict major adverse cardiovascular events (MACE). The current meta-analysis was performed using clinical outcome studies to evaluate the role of fQRS in coronary artery disease (CAD).

METHODS

A systematic search of electronic databases (Cochrane, Medline, Embase and Pubmed) from their inception to April 2014 was performed. Data were extracted from applicable articles to evaluate the prognostic value of fQRS in CAD.

RESULTS

A total of 16 observational studies about fQRS and CAD (n = 3,997 patients) were identified. Compared with the non-fQRS group, MACE and mortality were significantly higher in the fQRS group -odds ratios (OR) 3.19, 95 % confidence interval (95 % CI) [2.3, 4.42], p < 0.00001; OR 2.24, 95 % CI [1.71, 2.94], p < 0.0001. Patients developed Q waves, anterior-wall myocardial infarction (MI), and low left ventricular ejection fraction (LVEF) more frequently in the fQRS group than in the non-fQRS group-OR 2.59, 95 % CI [1.76, 3.81], p < 0.00001; OR 2.43, 95 % CI [1.07, 5.52], p = 0.03; OR - 6.43, 95 % CI [- 9.11, - 3.74], p < 0.00001.

CONCLUSION

Based on current evidence, fQRS was associated with increased MACE, mortality, Q waves, anterior-wall MI, and decreased LVEF in CAD. These findings show that fQRS is a reliable marker in CAD.

BRD4 regulates Nanog expression in mouse embryonic stem cells and preimplantation embryos

Bromodomain-containing protein 4 (BRD4) is an important epigenetic reader implicated in the pathogenesis of a number of different cancers and other diseases. Brd4-null mouse embryos die shortly after implantation and are compromised in their ability to maintain the inner cell mass, which gives rise to embryonic stem cells (ESCs). Here we report that BRD4 regulates expression of the pluripotency factor Nanog in mouse ESCs and preimplantation embryos, as well as in human ESCs and embryonic cancer stem cells. Inhibition of BRD4 function using a chemical inhibitor, small interfering RNAs, or a dominant-negative approach suppresses Nanog expression, and abolishes the self-renewal ability of ESCs. We also find that BRD4 associates with BRG1 (brahma-related gene 1, aka Smarca4 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a, member 4)), a key regulator of ESC self-renewal and pluripotency, in the Nanog regulatory regions to regulate Nanog expression. Our study identifies Nanog as a novel BRD4 target gene, providing new insights for the biological function of BRD4 in stem cells and mouse embryos. Knowledge gained from these non-cancerous systems will facilitate future investigations of how Brd4 dysfunction leads to cancers.

Increased serum cathepsin K in patients with coronary artery disease

PURPOSE

Cathepsin K is a potent collagenase implicated in human and animal atherosclerosis-based vascular remodeling. This study examined the hypothesis that serum CatK is associated with the prevalence of coronary artery disease (CAD).

MATERIALS AND METHODS

Between January 2011 and December 2012, 256 consecutive subjects were enrolled from among patients who underwent coronary angiography and percutaneous coronary intervention treatment. A total of 129 age-matched subjects served as controls.

RESULTS

The subjects' serum cathepsin K and high sensitive C-reactive protein (hs-CRP) and high-density lipoprotein cholesterol were measured. The patients with CAD had significantly higher serum cathepsin K levels compared to the controls (130.8±25.5 ng/mL vs. 86.9±25.5 ng/mL, p<0.001), and the patients with acute coronary syndrome had significantly higher serum cathepsin K levels compared to those with stable angina pectoris (137.1±26.9 ng/mL vs. 102.6±12.9 ng/mL, p<0.001). A linear regression analysis showed that overall, the cathepsin K levels were inversely correlated with the high-density lipoprotein levels (r=-0.29, p<0.01) and positively with hs-CRP levels (r=0.32, p<0.01). Multiple logistic regression analyses shows that cathepsin K levels were independent predictors of CAD (odds ratio, 1.76; 95% confidence interval, 1.12 to 1.56; p<0.01).

CONCLUSION

These data indicated that elevated levels of cathepsin K are closely associated with the presence of CAD and that circulating cathepsin K serves a useful biomarker for CAD.

Expression of human CD46 modulates inflammation associated with GalTKO lung xenograft injury

Evaluation of lungs from GalTKO.hCD46 pigs, genetically modified to lack the galactose-α(1,3)-galactose epitope (GalTKO) and to express human CD46, a complement regulatory protein, has not previously been described. Physiologic, hematologic and biochemical parameters during perfusion with heparinized fresh human blood were measured for 33 GalTKO.hCD46, GalTKO (n = 16), and WT pig lungs (n = 16), and 12 pig lungs perfused with autologous pig blood. Median GalTKO.hCD46 lung survival was 171 min compared to 120 for GalTKO (p = 0.27) and 10 for WT lungs (p < 0.001). Complement activation, platelet activation and histamine elaboration were significantly reduced during the first 2 h of perfusion in GalTKO.hCD46 lungs compared to GalTKO (ΔC3a at 120' 812 ± 230 vs. 1412 ± 1047, p = 0.02; ΔCD62P at 120' 9.8 ± 7.2 vs. 25.4 ± 18.2, p < 0.01; Δhistamine at 60' 97 ± 62 vs. 189 ± 194, p = 0.03). We conclude that, in addition to significant down-modulation of complement activation, hCD46 expression in GalTKO lungs diminished platelet and coagulation cascade activation, neutrophil sequestration and histamine release. Because GalTKO.hCD46 lung failure kinetics correlated directly with platelet and neutrophil sequestration, coagulation cascade activation and a rise in histamine levels within the first hour of perfusion, further progress will likely depend upon improved control of these pathways, by rationally targeted additional modifications to pigs and pharmacologic interventions.

Impact of lysophosphatidylcholine on survival and function of UEA-1(+)acLDL (+) endothelial progenitor cells in patients with coronary artery disease

Lysophosphatidylcholine (LPC) generated from oxidized low-density lipoprotein by lipoprotein-associated phospholipase A2 plays a key role in plaque inflammation and vulnerability. Endothelial progenitor cells (EPCs) can repair injured endothelium and exert anti-inflammatory effects of vulnerable plaque. We study the impact and mechanisms of LPC on UEA-1 and acLDL binding EPCs (UEA-1(+)acLDL(+) EPCs). UEA-1(+)acLDL(+) EPCs from coronary artery disease (CAD) patients were cultured and exposed to LPC at different concentrations and different timepoints. We determined the significant concentration (40 μM). UEA-1(+)acLDL(+) EPCs were preincubated for 30 min with pravastatin (20 μM) with LY249002, a specific inhibitor of the Akt signaling pathway, and exposed for 24 h to LPC 40 μM. The survival, migration, adhesion, and proliferation of UEA-1(+)acLDL(+) EPCs were assessed. To examine the mechanisms of LPC toxicity and pravastatin effects, phosphorylated Akt and endothelial nitric oxide synthase (eNOS) levels and the ratio of Bcl-2/Bax protein expression were assessed. LPC induced apoptosis and impaired migration and adhesion of UEA-1(+)acLDL(+) EPCs significantly. The detrimental effects of LPC were attenuated by pravastatin. However, when UEA-1(+)acLDL(+) EPCs were pretreated with pravastatin and LY249002, a specific inhibitor of the Akt signaling pathway, simultaneously, the beneficial effects of pravastatin were abolished. Furthermore, LPC suppressed Akt and eNOS phosphorylation and increased Bcl-2/Bax expression. The effects of LPC on Akt/eNOS and Bcl-2/Bax activity were reversed by pravastatin. In conclusion, LPC inhibited UEA-1(+)acLDL(+) EPCs survival and impaired its functions, and these were attributable to inhibition of the Akt/eNOS and Bcl-2/Bax pathway. Pravastatin reversed the detrimental action of LPC. These findings suggest that LPC inhibition can be a possible strategy for CAD through EPC revitalization.

Biochemical and clinical correlation of intraplaque neovascularization using contrast-enhanced ultrasound of the carotid artery

OBJECTIVE

Several biomarkers reflecting inflammatory or proteolytic activity have been known to represent plaque vulnerability. Moreover, a recent study confirmed that contrast-enhanced ultrasound (CEUS) can visualize intraplaque neovascularization (IPN) and demonstrate plaque vulnerability. In this study, we tried to demonstrate that IPN detected by CEUS was correlated with several well-known biomarkers and clinical outcome in patients with coronary artery disease (CAD).

METHODS

Patients with stable CAD were screened by conventional carotid ultrasound and patients with carotid plaque thickness more than 2 mm were performed by CEUS for the presence of IPN. Plasma levels of biomarkers and clinical outcomes were evaluated.

RESULTS

Among consecutive 89 patients fulfilled the inclusion criteria, 30 patients without IPN (group 1) and 59 patients with IPN (group 2) were analyzed. There were no significant difference in baseline characteristics except for mean age (62.9±10.1 yrs versus 68.4±9.6 yrs, p=0.015). On multivariate analysis, only MMP-9 (p=0.021, 95% CI 1.002-1.027) showed a significant association with IPN. But patients with IPN showed only trend for a history of cardiovascular disease (CVD) (44% versus 30%, p=0.19) and one-year cardiovascular events (CVE) (6.8% versus 3.3%, p=0.50) compared to group 1. Maximum plaque thickness (p=0.04, 95% CI 1.230-6.322) showed a significant correlation with the clinical outcome including CVD or CVE.

CONCLUSION

MMP-9 correlated with IPN on CEUS. For clinical implication, however, large prospective studies are needed.