Osteoblast Demineralization Induced by Oxidized High-Density Lipoprotein via the Inflammatory Pathway Is Suppressed by Adiponectin.

Low mineralization activity by human osteoblast cells (HOBs) indicates abnormal bone remodeling that potentially leads to osteoporosis. Oxidation, the most prominent form of high-density lipoprotein (HDL) modification, is suggested to affect bone mineralization through the inflammatory pathway. Adiponectin, which possesses anti-inflammatory activity, is postulated to have the ability to suppress the detrimental effects of oxidized HDL (oxHDL). This study aimed to investigate the effects of HDL before and after oxidation on markers of mineralization and inflammation. The protective effects of adiponectin on demineralization and inflammation induced by oxHDL were also investigated. OxHDL at 100 µg/mL protein had the highest inhibitory effect on mineralization, followed by lower calcium incorporation. OxHDL also had significantly lower expression of a mineralization marker (COL1A2) and higher expression of inflammatory markers (IL-6, TNF-α, and RELA proto-oncogene, NF-κß (p65)) compared to the unstimulated control group. These findings suggest that oxHDL reduces the mineralization activity of HOBs by increasing the expression of inflammatory markers. Interestingly, co-incubation of adiponectin and oxHDL in HOBs resulted in higher expression of mineralization markers (ALPL, COL1A2, BGLAP, and RUNX2) and significantly reduced all targeted inflammatory markers compared to the oxHDL groups. On the contrary, HDL increased the expression of mineralization markers (COL1A2 and STAT-3) and exhibited lower expression of inflammatory cytokines (IL-6 and TNF-α), proving the protective effect of HDL beyond the reverse cholesterol transport activity.

Observational study of the status of coronary risk biomarkers among Negritos with metabolic syndrome in the east coast of Malaysia.

OBJECTIVES: To determine the prevalence of metabolic syndrome (MS), ascertain the status of coronary risk biomarkers and establish the independent predictors of these biomarkers among the Negritos. SETTINGS: Health screening programme conducted in three inland settlements in the east coast of Malaysia and Peninsular Malaysia. SUBJECTS: 150 Negritos who were still living in three inland settlements in the east coast of Malaysia and 1227 Malays in Peninsular Malaysia. These subjects were then categorised into MS and non-MS groups based on the International Diabetes Federation (IDF) consensus worldwide definition of MS and were recruited between 2010 and 2015. The subjects were randomly selected and on a voluntary basis. PRIMARY AND SECONDARY OUTCOME MEASURES: This study was a cross-sectional study. Serum samples were collected for analysis of inflammatory (hsCRP), endothelial activation (sICAM-1) and prothrombogenesis [lp(a)] biomarkers. RESULTS: MS was significantly higher among the Malays compared with Negritos (27.7%vs12.0%). Among the Malays, MS subjects had higher hsCRP (p=0.01) and sICAM-1 (p<0.05) than their non-MS counterpart. There were no significant differences in all the biomarkers between MS and the non-MS Negritos. However, when compared between ethnicity, all biomarkers were higher in Negritos compared with Malays (p<0.001). Binary logistic regression analysis affirmed that Negritos were an independent predictor for Lp(a) concentration (p<0.001). CONCLUSIONS: This study suggests that there may possibly be a genetic influence other than lifestyle, which could explain the lack of difference in biomarkers concentration between MS and non-MS Negritos and for Negritos predicting Lp(a).

Low serum high density lipoprotein cholesterol concentration is an independent predictor for enhanced inflammation and endothelial activation.

BACKGROUND: Inflammation, endothelial activation and oxidative stress have been established as key events in the initiation and progression of atherosclerosis. High-density lipoprotein cholesterol (HDL-c) is protective against atherosclerosis and coronary heart disease, but its association with inflammation, endothelial activation and oxidative stress is not well established. OBJECTIVES: (1) To compare the concentrations of biomarkers of inflammation, endothelial activation and oxidative stress in subjects with low HDL-c compared to normal HDL-c; (2) To examine the association and correlation between HDL-c and these biomarkers and (3) To determine whether HDL-c is an independent predictor of these biomarkers. METHODS: 422 subjects (mean age±SD = 43.2±11.9 years) of whom 207 had low HDL-c concentrations (HDL-c <1.0 mmol/L and <1.3 mmol/L for males and females respectively) and 215 normal controls (HDL-c ≥1.0 and ≥1.3 mmol/L for males and females respectively) were recruited in this study. The groups were matched for age, gender, ethnicity, smoking status, diabetes mellitus and hypertension. Fasting blood samples were collected for analysis of biomarkers of inflammation [high-sensitivity C-reactive protein (hsCRP) and Interleukin-6 (IL-6)], endothelial activation [soluble Vascular Cell Adhesion Molecule-1 (sVCAM-1), soluble Intercellular Adhesion Molecule-1 (sICAM-1) and E-selectin)] and oxidative stress [F2-Isoprostanes, oxidized Low Density Lipoprotein (ox-LDL) and Malondialdehyde (MDA)]. RESULTS: Subjects with low HDL-c had greater concentrations of inflammation, endothelial activation and oxidative stress biomarkers compared to controls. There were negative correlations between HDL-c concentration and biomarkers of inflammation (IL-6, p = 0.02), endothelial activation (sVCAM-1 and E-selectin, p = 0.029 and 0.002, respectively), and oxidative stress (MDA and F2-isoprostane, p = 0.036 and <0.0001, respectively). Multiple linear regression analysis showed HDL-c as an independent predictor of IL-6 (p = 0.02) and sVCAM-1 (p<0.03) after correcting for various confounding factors. CONCLUSION: Low serum HDL-c concentration is strongly correlated with enhanced status of inflammation, endothelial activation and oxidative stress. It is also an independent predictor for enhanced inflammation and endothelial activation, which are pivotal in the pathogenesis of atherosclerosis and atherosclerosis-related complications.