RATIONALE:Patients with elevated levels of lipoprotein(a) Lp(a) are hallmarked by increased metabolic activity in the arterial wall on positron emission tomography/computed tomography, indicative of ...a proinflammatory state.
OBJECTIVE:We hypothesized that Lp(a) induces endothelial cell inflammation by rewiring endothelial metabolism.
METHODS AND RESULTS:We evaluated the impact of Lp(a) on the endothelium and describe that Lp(a), through its oxidized phospholipid content, activates arterial endothelial cells, facilitating increased transendothelial migration of monocytes. Transcriptome analysis of Lp(a)-stimulated human arterial endothelial cells revealed upregulation of inflammatory pathways comprising monocyte adhesion and migration, coinciding with increased 6-phophofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB)-3–mediated glycolysis. ICAM (intercellular adhesion molecule)-1 and PFKFB3 were also found to be upregulated in carotid plaques of patients with elevated levels of Lp(a). Inhibition of PFKFB3 abolished the inflammatory signature with concomitant attenuation of transendothelial migration.
CONCLUSIONS:Collectively, our findings show that Lp(a) activates the endothelium by enhancing PFKFB3-mediated glycolysis, leading to a proadhesive state, which can be reversed by inhibition of glycolysis. These findings pave the way for therapeutic agents targeting metabolism aimed at reducing inflammation in patients with cardiovascular disease.
Macrophage apoptosis in advanced atheromata, a key process in plaque necrosis, involves the combination of ER stress with other proapoptotic stimuli. We show here that oxidized phospholipids, ...oxidized LDL, saturated fatty acids (SFAs), and lipoprotein(a) trigger apoptosis in ER-stressed macrophages through a mechanism requiring both CD36 and Toll-like receptor 2 (TLR2). In vivo, macrophage apoptosis was induced in SFA-fed, ER-stressed wild-type but not
Cd36
−/− or
Tlr2
−/− mice. For atherosclerosis, we combined TLR2 deficiency with that of TLR4, which can also promote apoptosis in ER-stressed macrophages. Advanced lesions of fat-fed
Ldlr
−/− mice transplanted with
Tlr4
−/−
Tlr2
−/− bone marrow were markedly protected from macrophage apoptosis and plaque necrosis compared with WT →
Ldlr
−/− lesions. These findings provide insight into how atherogenic lipoproteins trigger macrophage apoptosis in the setting of ER stress and how TLR activation might promote macrophage apoptosis and plaque necrosis in advanced atherosclerosis.
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► Atherogenic lipids trigger CD36/TLR2-dependent apoptosis in ER-stressed macrophages ► Lipoprotein(a), a potent risk factor for CAD in humans, activates this apoptosis pathway ► CD36 and TLR2 deficiency suppressed macrophage apoptosis in SFA-fed, ER-stressed mice ► TLR deficiency protected atheromata of
Ldlr
−/− mice from apoptosis and plaque necrosis
Background Oxidized phospholipids (OxPL) on apolipoprotein B-100 (OxPL–apoB) reflect the biological activity of lipoprotein(a) (Lpa) and predict cardiovascular disease events. However, studies with ...statins and low-fat diets show increases in OxPL–apoB and Lp(a). Objective This study evaluated changes in OxPL–apoB and Lp(a) with extended-release niacin (N), ezetimibe/simvastatin (E/S) and combination E/S/N. A systematic literature review of previously published trials, measuring both OxPL–apoB and Lp(a) after therapeutic interventions, was also performed. Methods OxPL–apoB and Lp(a) were measured in 591 patients at baseline and 24 weeks after therapy with N, E/S, or E/S/N in a previously completed randomized trial of hypercholesterolemic patients. The literature review included 12 trials and 3896 patients evaluating statins, low-fat diets, antisense to apolipoprotein(a) and lipid apheresis. Results Niacin decreased OxPL–apoB levels (median interquartile range; 3.5 2.2–9.2 nM to 3.1 1.8–7.2 nM, P < .01) and Lp(a) (10.9 4.6–38.4 to 9.3 3.1–32.9 mg/dL, P < .01). In contrast, E/S and E/S/N significantly increased OxPL–apoB (3.5 2.1–7.8 to 4.9 3.0–11.1 nM, P < .01) and (3.3 1.9–9.3 to 4.3 2.6–11.2 nM, P < .01), respectively and Lp(a) (11.5 6.1–36.4 to 14.9 6.6–54.6 mg/dL, P < .01) and (11.3 5.4–43.8 to 11.6 5.9–52.8 mg/dL, P < .01), respectively. The systematic review of statins and diet demonstrated 23.8% and 21.3% mean increases in OxPL–apoB and 10.6% and 19.4% increases in Lp(a), respectively. However 44.1% and 52.0% decreases in OxPL–apoB and Lp(a), respectively, were present with Lp(a)–lowering therapies. Conclusions This study demonstrates differential changes in OxPL–apoB and Lp(a) with various lipid-lowering approaches. These changes in OxPL–apoB and Lp(a) may provide insights into the results and interpretation of recent cardiovascular disease outcomes trials.
...complete data on high-sensitivity C-reactive protein, Lp(a), and other inflammatory biomarkers were not available; thus any mechanisms of TBR reduction beyond lowering of apoB-containing ...lipoproteins cannot be inferred. (8) should be congratulated on performing this unique translational study that takes advantage of a therapeutic technique coupled to an imaging technique to provide insights into acute plaque biology. Because apheresis has been shown to reduce cardiovascular events in patients who have both high LDL-C and high Lp(a), one could hypothesize that the FDG signal reduction noted here should reflect the clinical benefit in patients with appropriate responses.
Abstract Aims Whether adverse effect of statins on glycaemic indices is common to all statins remains controversial and as yet data for pitavastatin are limited. We sought to assess the effects of ...pitavastatin on glycaemia and new-onset diabetes (NOD) in non-diabetic individuals using data from RCT pooled together by means of a meta-analysis. Materials and methods We searched Medline, Cochrane, Embase and clinical trials registries websites until November-2014 for ≥12-week follow-up placebo or statin-controlled RCT of pitavastatin that included participants without diabetes and reported on fasting blood glucose (FBG), HbA1c or NOD. We additionally sought studies by consulting with Kowa Ph. Ltd. The association of pitavastatin with the outcomes were estimated by random-effects meta-analyses. Heterogeneity was assessed by the I2 statistic and sensitivity and subgroup analyses, and publication bias with funnel plots and Egger and Harbord Tests. Results 15 studies (approx. 1600 person-years) were included. No significant differences associated with pitavastatin (vs. control) were observed for FBG (MD −0.01 mg/dL 95%CI −0.77, 0.74, I2 = 0%), HbA1c (MD −0.03% 95%CI −0.11, 0.05, I2 = 43%) or NOD (RR 0.70 95%CI 0.30, 1.61; RD 0.0 95%CI −0.004, 0.003; I2 = 0%). Sensitivity and subgroup analyses (including type of control placebo or other statin, pitavastatin dose or follow-up did not yield significant results. Potential publication bias may occur for NOD. Conclusions In the present meta-analysis pitavastatin did not adversely affect glucose metabolism or diabetes development compared with placebo or other statins.
Elevated apoC-III levels predict increased cardiovascular risk when present on LDL and HDL particles. We developed novel high-throughput chemiluminescent ELISAs that capture apoB, lipoprotein (a) ...Lp(a), and apoA-I in plasma and then detect apoC-III on these individual lipoproteins as apoCIII-apoB, apoCIII-Lp(a), and apoCIII-apoAI complexes, respectively. We assessed the effects on these complexes of placebo or 100-300 mg volanesorsen, a generation 2.0+ antisense drug that targets apoC3 mRNA in patients with hypertriglyceridemia, including familial chylomicronemia syndrome (n = 3), volanesorsen monotherapy (n = 51), and as add-on to fibrate (n = 26), treated for 85 days and followed for 176 days. Compared with placebo, volanesorsen was associated with an 82.3 ± 11.7%, 81.3 ± 15.7%, and 80.8 ± 13.6% reduction in apoCIII-apoB, apoCIII-Lp(a), and apoCIII-apoA-I, respectively (300 mg dose;P< 0.001 for all), at day 92. Strong correlations in all assay measures were noted with total plasma apoC-III, chylomicron-apoC-III, and VLDL-apoC-III. In conclusion, novel high-throughput ELISAs were developed to detect lipoprotein-associated apoC-III, including for the first time on Lp(a). Volanesorsen uniformly lowers apoC-III on apoB-100, Lp(a), and apoA-I lipoproteins, and may be a potent agent to reduce triglycerides and cardiovascular risk mediated by apoC-III.
It is postulated that lipoprotein (a) Lp(a) inhibits fibrinolysis, but this hypothesis has not been tested in humans due to the lack of specific Lp(a) lowering agents. Patients with elevated Lp(a) ...were randomized to antisense oligonucleotide IONIS-APO(a)Rx directed to apo(a) (n = 7) or placebo (n = 10). Ex vivo plasma lysis times and antigen concentrations of plasminogen, factor XI, plasminogen activator inhibitor 1, thrombin activatable fibrinolysis inhibitor, and fibrinogen at baseline, day 85/92/99 (peak drug effect), and day 190 (3 months off drug) were measured. The mean ± SD baseline Lp(a) levels were 477.3 ± 55.9 nmol/l in IONIS-APO(a)Rx and 362.1 ± 89.9 nmol/l in placebo. The mean± SD percentage change in Lp(a) for IONIS-APO(a)Rx was −69.3 ± 12.2% versus −5.4 ± 6.9% placebo (P < 0.0010) at day 85/92/99 and −15.6 ± 8.9% versus 3.2 ± 12.2% (P = 0.003) at day 190. Clot lysis times and coagulation/fibrinolysis-related biomarkers showed no significant differences between IONIS-APO(a)Rx and placebo at all time points. Clot lysis times were not affected by exogenously added Lp(a) at concentrations up to 200 nmol/l to plasma with very low (12.5 nmol/l) Lp(a) levels, whereas recombinant apo(a) had a potent antifibrinolytic effect. In conclusion, potent reductions of Lp(a) in patients with highly elevated Lp(a) levels do not affect ex vivo measures of fibrinolysis; the relevance of any putative antifibrinolytic effects of Lp(a) in vivo needs further study.
Lipoprotein(a) Lp(a) is reported as Lp(a) particle mass (mg/dL) or molar concentration of apolipoprotein(a) apo(a) (nmol/L), which is considered the gold standard. Values are often converted from one ...measurement to the other but the validity of this is unknown.
To quantify the relationship between Lp(a) molar concentration and Lp(a) mass in the context of various Lp(a) level thresholds and apo(a) isoform size.
In all samples, Lp(a) levels in molar concentration and apo(a) isoform size were determined at the Northwest Lipid Metabolism and Diabetes Research Laboratories (NLMDRL). Lp(a) mass levels were determined at the University of California, San Diego (UCSD) (1635 samples), by 5 commercially available assays: Denka 1 and Denka 2 (each 80 samples), 2 turbidimetric assays (2545 and 2673 samples, respectively), and an enzyme-linked immunosorbent assay (2605 samples). The ratios between Lp(a) molar concentration and mass (eg, nmol/L/mg/dL) were calculated and related to apo(a) isoform size.
The mean (SD) ratios for NLMDRL/UCSD, NLMDRL/Denka1, and NLMDRL/Denka2 were 2.42 (1.25), 1.64 (0.18), and 2.02 (0.22), respectively. The ratios for NLMDRL/UCSD, NLMDRL/Denka1, and NLMDRL/Denka2 increased by Lp(a) cutoffs, with ratios of 1.82, 1.52, and 1.87, respectively, for Lp(a) < 75 nmol/L and 2.80, 1.89, and 2.24, respectively, for Lp(a) > 125 nmol/L. For the commercial turbidimetric assays and enzyme-linked immunosorbent assay, the ratios ranged from <1 to >5.
Lp(a) molar/mass ratios are threshold, method, and isoform dependent. A single conversion factor between assays is not appropriate. These data support the transition of Lp(a) mass assays to molar concentration to improve diagnostic and clinical interpretation of Lp(a)-mediated risk.
•Lipoprotein(a) Lp(a) in molar concentration, mass, and isoforms was determined in 6 studies•Lp(a) molar/mass ratios were calculated with 1 academic and 5 commercial assays•Lp(a) molar/mass ratios are threshold, method, and isoform dependent.•A single conversion factor between assays is not appropriate.•Molar concentration assays should be used clinically to assess Lp(a)-mediated risk.
Elevated lipoprotein (a) Lp(a) levels are a causal risk factor for coronary heart disease. Accumulating evidence suggests that Lp(a) can stimulate cellular inflammatory responses through the ...kringle-containing apolipoprotein (a) apo(a) component. Here, we report that recombinant apo(a) containing 17 kringle (17K) IV domains elicits a dose-dependent increase in interleukin (IL)-8 mRNA and protein expression in THP-1 and U937 macrophages. This effect was blunted by mutation of the lysine binding site in apo(a) kringle IV type 10, which resulted in the loss of oxidized phospholipid (oxPL) on apo(a). Trypsin-digested 17K had the same stimulatory effect on IL-8 expression as intact apo(a), while enzymatic removal of oxPL from apo(a) significantly blunted this effect. Using siRNA to assess candidate receptors, we found that CD36 and TLR2 may play roles in apo(a)-mediated IL-8 stimulation. Downstream of these receptors, inhibitors of MAPKs, Jun N-terminal kinase and ERK1/2, abolished the effect of apo(a) on IL-8 gene expression. To assess the roles of downstream transcription factors, luciferase reporter gene experiments were conducted using an IL-8 promoter fragment. The apo(a)-induced expression of this reporter construct was eliminated by mutation of IL-8 promoter binding sites for either NF-κB or AP-1. Our results provide a mechanistic link between oxPL modification of apo(a) and stimulation of proinflammatory intracellular signaling pathways.
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