Cell-free, high-density lipoprotein-specific phospholipid efflux assay predicts incident cardiovascular disease.

BACKGROUNDCellular cholesterol efflux capacity (CEC) is a better predictor of cardiovascular disease (CVD) events than HDL-cholesterol (HDL-C) but is not suitable as a routine clinical assay.METHODSWe developed an HDL-specific phospholipid efflux (HDL-SPE) assay to assess HDL functionality based on whole plasma HDL apolipoprotein-mediated solubilization of fluorescent phosphatidylethanolamine from artificial lipid donor particles. We first assessed the association of HDL-SPE with prevalent coronary artery disease (CAD): study I included NIH severe-CAD (n = 50) and non-CAD (n = 50) participants, who were frequency matched for sex, BMI, type 2 diabetes mellitus, and smoking; study II included Japanese CAD (n = 70) and non-CAD (n = 154) participants. We also examined the association of HDL-SPE with incident CVD events in the Prevention of Renal and Vascular End-stage Disease (PREVEND) study comparing 340 patients with 340 controls individually matched for age, sex, smoking, and HDL-C levels.RESULTSReceiver operating characteristic curves revealed stronger associations of HDL-SPE with prevalent CAD. The AUCs in study I were as follows: HDL-SPE, 0.68; apolipoprotein A-I (apoA-I), 0.62; HDL-C, 0.63; and CEC, 0.52. The AUCs in study II were as follows: HDL-SPE, 0.83; apoA-I, 0.64; and HDL-C, 0.53. Also longitudinally, HDL-SPE was significantly associated with incident CVD events independent of traditional risk factors with ORs below 0.2 per SD increment in the PREVEND study (P < 0.001).CONCLUSIONHDL-SPE could serve as a routine clinical assay for improving CVD risk assessment and drug discovery.TRIAL REGISTRATIONClinicalTrials.gov NCT01621594.FUNDINGNHLBI Intramural Research Program, NIH (HL006095-06).

γGT and PCSK9 variants in subjects with hyper-LDL-cholesterolemia.

BACKGROUND AND AIM: Gain-of-function (GOF) variants of proprotein convertase subtilisin/kexin type 9 (PCSK9) gene cause high blood low-density lipoprotein (LDL) cholesterol and PCSK9 levels, which are respectively the markers of cardiovascular disease (CVD). High blood activity of gamma-glutamyl transpeptidase (γGT), a pro-oxidant induced by oxidative conditions, is also a marker of CVD. There may be an association between γGT and PCSK9 variants. We aimed to examine the γGT activity by a GOF variant, p.E32K, of PCSK9 in subjects with hyper-LDL-cholesterolemia, an at-risk state for CVD. METHODS: This study enrolled 114 subjects (mean age, 59 years; 38 males) with hyper-LDL-cholesterolemia who underwent a genotype assay for identification of p.E32K variant and enzymatic measurement of γGT activity. The relationship between the γGT activity and p.E32K was analyzed. RESULTS: γGT activity was significantly lower (median, 21 IU/L) in subjects with p.E32K (n = 12) than in those without the variant (30 IU/L, P < 0.05). The results remained confirmed by multivariate-adjusted analysis. CONCLUSIONS: An inverse association was found between γGT and p.E32K, a GOF variant. Elucidation of the mechanism for their association may help understand the development of CVD by PCSK9 variants.

A novel loop-mediated isothermal amplification-based genotyping method and its application for identifying proprotein convertase subtilisin/kexin type 9 variants in familial hypercholesterolemia.

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a key role in regulating low-density lipoprotein levels in plasma. While PCSK9 variants are causatively associated with familial hypercholesterolemia (FH), additional genotyping methods for FH targeting PCSK9 variants are required in a clinical setting. Loop-mediated isothermal amplification (LAMP) is a unique amplification method that amplifies a target gene under isothermal conditions (60-65 °C). However, a robust standardized method has not yet been established for LAMP-based genetic screening tests for genetic diseases, including FH. The present study aimed to develop a novel modification of the LAMP method designed to genotype single nucleotide variants (SNVs) and to apply it for the detection of PCSK9 variants. METHODS: Using short quenching probes (≤ 10 nucleotides) for the loop structures of LAMP amplicons, accurate detection of SNVs was verified separately for each allele, without any additional procedures, within 3 h. The diagnostic performance of this method in detecting PCSK9 variants was validated in FH patients. RESULTS: All PCSK9 variants tested via conventional sequencing in FH patients were successfully detected using this novel LAMP method. CONCLUSIONS: We developed a LAMP-based genotyping method to detect PCSK9 variants in FH. Compared to conventional sequencing, our genotyping method is relatively convenient and time-efficient and is suitable for the screening of FH in clinical settings. Future studies on various genes are also warranted.

LDL-cholesterol and PCSK9 in patients with familial hypercholesterolemia: influence of PCSK9 variants under lipid-lowering therapy.

BACKGROUND: Familial hypercholesterolemia (FH), an autosomal dominant genetic disease with the elevated levels of low-density lipoprotein (LDL) cholesterol (LDL-C), increases the risk of coronary artery disease (CAD). The proprotein convertase subtilisin/kexin type 9 (PCSK9) gene is associated with FH. There is a positive relationship between circulating LDL-C and PCSK9 levels, a potential CAD condition, without lipid-lowering therapy (LLT); however, we do not know whether their correlation exists in FH patients under LLT. METHODS: This study compared the correlation of PCSK9 variants among patients with FH under LLT (n = 70; mean age, 53 years; male, 63%). LDLR, PCSK9 and APOB variants were analyzed using next-generation sequencing. RESULTS: The LDL-C and PCSK9 levels in patients with gain-of-function (GOF) variants of PCSK9 (n = 7) were mostly similar to those in patients with LDLR variants (n = 17) or variant-negative patients (n = 46). A significant positive correlation was observed between LDL-C and PCSK9 levels in patients with GOF variants of PCSK9 (r = 0.79, p = 0.04), but not in patients with LDLR variants or variant-negative patients. CONCLUSION: The LDL-C-PCSK9 correlation is suggested to be retained in FH patients with GOF variants of PCSK9 even under LLT, and these variants can be used as molecular markers for additional treatment with statins in FH patients.

The Effect of Helicobacter pylori Eradication on Lipid Levels: A Meta-Analysis.

Introduction: Helicobacter pylori (H. pylori) infection is positively associated with cardiovascular diseases, but the involvement of lipids in this association remains unclear. The present study reviewed the changes in circulating lipid levels following H. pylori eradication. Methods: A PubMed database was searched until December 2020 to identify randomized control trials (RCTs) and non-RCTs investigating the effect of H. pylori eradication on the lipid levels in inverse variance-weighted, random-effects meta-analyses. Results: A total of 24 studies (four RCTs and 20 non-RCTs) with 5270 participants were identified. The post-eradication levels were increased for high-density lipoprotein cholesterol (HDL-C; mean difference (MD) 2.28 mg/dL, 95% confidence interval (CI) 1.90 to 2.66) and triglyceride (TG; MD 3.22 mg/dL, 95% CI 1.13 to 5.31) compared with the pre-eradication levels. H. pylori eradication resulted in little to no difference in the low-density lipoprotein-cholesterol levels (MD -2.33 mg/dL, 95% CI -4.92 to 0.26). In the analyses of RCTs only, the findings for elevated HDL-C levels, but not TG, were robust. Conclusions: H. pylori eradication increases the HDL-C levels. Further studies are needed to elucidate the effects of lipid changes following H. pylori eradication on cardiovascular diseases.

Lipoprotein(a) and Familial Hypercholesterolemia: A Short Review Including the Laboratory Viewpoint.

Lipoprotein(a) (Lp(a)) and low-density lipoprotein cholesterol (LDL-C) are risk factors for cardiovascular disease (CVD). Individuals with familial hypercholesterolemia (FH) have a risk for CVD due to a high LDL-C value. Lp(a) also increases the CVD risk in FH individuals; thus, the Lp(a) value should be carefully managed. The LDL-C value may partly include Lp(a)-cholesterol (Lp(a)-C) in the measurement. Based on the LDL-C value, some individuals are likely misclassified as having FH and/or the status of treatment of FH can be monitored. The present review describes about Lp(a) in FH individuals in terms of the measurement issue of Lp(a) and the related management of FH.

Risk of cardiovascular disease with lipoprotein(a) in familial hypercholesterolemia: a review.

INTRODUCTION: Lipoprotein(a) (Lp[a]) is a risk factor of cardiovascular disease (CVD). Familial hypercholesterolemia (FH), which exhibits high low-density lipoprotein cholesterol (LDL-C) levels, is a risk factor of CVD. The relationship of Lp(a) with CVD has been characterized in populations specific to FH. MATERIAL AND METHODS: Studies reporting on the relationship of Lp(a) with CVD among FH subjects via PubMed up to 2020 were reviewed. RESULTS: Eight studies were identified as eligible. In the meta-analyses, a high Lp(a) level was significantly and predictively associated with CVD compared to a low Lp(a) level in 2 cross-sectional studies (odds ratio = 2.57; 95% confidence interval (CI): 1.16-5.73) and 6 cohort studies (risk/hazard ratio = 1.91; 95% CI: 1.50-2.43). The totally integrated relative risk of these studies was 1.97 (95% CI: 1.57-2.46). CONCLUSIONS: FH subjects with high Lp(a) levels can have a high CVD risk, and besides LDL-C, attention should be paid to Lp(a) levels in FH subjects.

Fully Automated Molecular Diagnostic System "Simprova" for Simultaneous Testing of Multiple Items.

Nucleic acid amplification-based diagnostics is known as one of the molecular diagnostic systems that allows higher sensitive detection of pathogens than test methods such as immunoassay. However, it has not been widely used because it is complicated to use and takes a long time to generate results. On the other hand, development of fully automated molecular diagnostic systems has been growing around the world as demand for such systems from physicians and laboratory technicians has increased. To meet this demand, we have developed the "Simprova" fully automated molecular diagnostic system, which takes advantage of LAMP (Loop-mediated Isothermal Amplification), a method Eiken Chemical Co., Ltd. invented. Simprova comprises a master unit that controls the entire system and a test unit that extracts and purifies nucleic acid from samples (pretreatment), and uses the LAMP method to detect and amplify nucleic acid. Users can obtain test results automatically by simply installing a pretreatment cartridge, a multi-well testing chip and the sample in the test unit. The multi-well testing chip has 25 reaction wells connected by channels and enables simultaneous testing of multiple targets with one sample. Turnaround time for one test is approximately 30 minutes. Since a conventional extraction and purification method using magnetic-bead separation is used for the pretreatment, nucleic acid can be extracted from serum, plasma, whole blood, urine, and sputum, for example. In addition, the system can perform random-access testing by connecting four test units to the master unit to realize near-the-patient testing. Simprova is therefore a robust and useful system for a wide variety of applications.

Functional implication of archaeal homologues of human RNase P protein pair Pop5 and Rpp30.

PhoPop5 and PhoRpp30 in the hyperthermophilic archaeon Pyrococcus horikoshii, homologues of human ribonuclease P (RNase P) proteins hPop5 and Rpp30, respectively, fold into a heterotetramer [PhoRpp30-(PhoPop5)2-PhoRpp30], which plays a crucial role in the activation of RNase P RNA (PhopRNA). Here, we examined the functional implication of PhoPop5 and PhoRpp30 in the tetramer. Surface plasmon resonance (SPR) analysis revealed that the tetramer strongly interacts with an oligonucleotide including the nucleotide sequence of a stem-loop SL3 in PhopRNA. In contrast, PhoPop5 had markedly reduced affinity to SL3, whereas PhoRpp30 had little affinity to SL3. SPR studies of PhoPop5 mutants further revealed that the C-terminal helix (α4) in PhoPop5 functions as a molecular recognition element for SL3. Moreover, gel filtration indicated that PhoRpp30 exists as a monomer, whereas PhoPop5 is an oligomer in solution, suggesting that PhoRpp30 assists PhoPop5 in attaining a functionally active conformation by shielding hydrophobic surfaces of PhoPop5. These results, together with available data, allow us to generate a structural and mechanistic model for the PhopRNA activation by PhoPop5 and PhoRpp30, in which the two C-terminal helices (α4) of PhoPop5 in the tetramer whose formation is assisted by PhoRpp30 act as binding elements and bridge SL3 and SL16 in PhopRNA.