Proprotein convertase subtilisin/kexin-type 9 (PCSK9) and soluble low-density lipoprotein receptor (sLDLR) are circulating proteins that down regulate LDLR-mediated uptake of plasma LDL-cholesterol into cells. In healthy individuals, plasma PCSK9 and sLDLR levels correlate with total cholesterol and triglycerides, respectively. Because cancer reprograms lipid metabolism, it may alter both the circulating levels of these proteins and their correlations with total cholesterol and triglycerides. To test this possibility, we measured PCSK9, sLDLR, total cholesterol, and triglycerides in plasma from healthy subjects and patients with colorectal cancer liver metastases (CRLM), classified as early recurrent or non-recurrent after liver resection. Plasma PCSK9 and sLDLR were measured using specific ELISA kits. Total cholesterol and triglycerides were measured by enzymatic colorimetry. Compared with healthy subjects, CRLM patients had 4- to 6-fold higher sLDLR levels, regardless of recurrence category or gender (P < 0.0001). sLDLR strongly correlated with triglyceride levels (P < 0.0001). Correlations between PCSK9 and sLDLR, total cholesterol, and triglycerides varied by gender and CRLM category. Low PCSK9 levels were associated with larger tumors in early recurrent CRLM, particularly in women (P < 0.01). In women, total cholesterol above the median predicted poorer 5-year overall survival [HR (95

Background. Proprotein convertase subtilisin/kexin-type 9 (PCSK9) and soluble low-density lipoprotein receptor (sLDLR) are blood proteins that down regulate LDLR-mediated uptake of plasma LDL-cholesterol into cells. In healthy subjects, the plasma level of PCSK9 and sLDLR strongly correlates with that of total cholesterol (TC) and triglycerides (TG), respectively. Since cancer is known to reprogram lipid metabolism, it may also alter the plasma levels of PCSK9 and sLDLR as well as their correlations with TC and TG. To verify this hypothesis, we measured the levels of PCSK9, sLDLR, TC, and TG in the plasma of healthy subjects and patients with colorectal cancer liver metastases (CRLM), categorized as early recurrent (ER) or non-recurrent (NR) after liver resection. Methods. The plasma levels of PCSK9 and sLDLR were determined using specific ELISA kits, those of TC and TG by enzymatic colorimetry. Results. Relative to healthy subjects, CRLM patients carried 4 to 6 higher levels of sLDLR, irrespective of category or gender ( p < 0.0001). These levels strongly correlated with those of TG ( p < 0.0001). PCSK9 correlations with sLDLR, TC, or TG varied with gender or CRLM category. Low PCSK9 levels were associated with large tumor size in CRLM_ER, particularly in women ( p < 0.01). Also in women, a TC level above the median is predictive of a poor 5-year overall survival [HR (95% CI) 1.70 (1.07 – 2.71; p = 0.0152]. Conclusions. High plasma sLDLR is a potential diagnostic biomarker of CRLM. In CRLM_ER women, low plasma PCSK9 indicates the presence of large tumors and, in CRLM women in general, high plasma TC is an unfavorable prognostic biomarker. Thus, early recurrence and gender ought to be considered when examining the clinical significance of lipid dysregulation in CRLM patients.

The remarkable reported in vitro and in vivo antiviral activity of a commercial, naturally derived, isoquercitrin sample (IQC90) against Ebola (EBOV), Zika virus (ZIKV), and SARS-CoV-2 could not be confirmed with a greater purity isoquercitrin (IQC). To resolve this discrepancy, IQC90 was subjected to a two-step, quantitative bioassay-guided fractionation employing countercurrent separation and gel filtration monitored by inhibition of syncytium formation in HEK293 cells transfected with SARS-CoV-2 spike protein and ACE2. This process revealed the IQC90 antiviral activity to be due to a new family of 21-hydroxyoleanane-3-O-oligosaccharides, named dicitriosides, present at <1 mol %, rather than IQC. The two dominant dicitriosides, the hexoside, dicitrioside A1 (1), and the pentoside, dicitrioside B1 (2), inhibited syncytia formation with an IC50 = 0.530 μM; 25-fold more active than IQC90 (IC50 = 12.8 μM). Beyond anti-SARS-CoV-2 activity, dicitrioside B1 (2) also prevented EBOV infection of Vero E6 cells, supporting the conclusion that the dicitriosides inherit the promising potential of IQC90 as antiviral leads for clinical translation. Ultrahigh field 1.1 GHz NMR spectroscopy, particularly 1D selective TOCSY experiments and nuclear genotyping via quantum-mechanical spin analysis, enabled structure elucidation and provided definitive reference points for the dicitriosides as complex oligoglycoside esters.

Background Several in silico studies have determined that quercetin, a plant flavonol, could bind with strong affinity and low free energy to SARS-CoV-2 proteins involved in viral entry and replication, suggesting it could block infection of human cells by the virus. In the present study, we examined the ex vivo ability of quercetin to inhibit of SARS-CoV-2 replication and explored the mechanisms of this inhibition. Methods Green monkey kidney Vero E6 cells and in human colon carcinoma Caco-2 cells were infected with SARS-CoV-2 and incubated in presence of quercetin; the amount of replicated viral RNA was measured in spent media by RT-qPCR. Since the formation of syncytia is a mechanism of SARS-CoV-2 propagation, a syncytialization model was set up using human embryonic kidney HEK293 co-expressing SARS-CoV-2 Spike (S) protein and human angiotensin converting enzyme 2 (ACE2), [HEK293(S + ACE2) cells], to assess the effect of quercetin on this cytopathic event by microscopic imaging and protein immunoblotting. Results Quercetin inhibited SARS-CoV-2 replication in Vero E6 cells and Caco-2 cells in a concentration-dependent manner with a half inhibitory concentration (IC 50 ) of 166.6 and 145.2 µM, respectively. It also inhibited syncytialization of HEK293(S + ACE2) cells with an IC 50 of 156.7 µM. Spike and ACE2 co-expression was associated with decreased expression, increased proteolytic processing of the S protein, and diminished production of the fusogenic S2’ fragment of S. Furin, a proposed protease for this processing, was inhibited by quercetin in vitro with an IC 50 of 116 µM. Conclusion These findings suggest that at low 3-digit micromolar concentrations of quercetin could impair SARS-CoV-2 infection of human cells partly by blocking the fusion process that promotes its propagation.

Proprotein Convertase Subtilisin/Kexin-type 9 (PCSK9) is a circulating negative regulator of hepatic low-density lipoprotein receptor (LDLR), which clears cholesterol from blood. Gain-of-function genetic mutations that amplify PCSK9 activity have been found to cause potentially lethal familial hypercholesterolemia. Inversely, reduction of its activity through loss-of-function genetics or with pharmaceuticals was shown to increase hepatic LDLR, to lower blood cholesterol, and to protect against cardiovascular diseases. New epidemiological and experimental evidence suggests that this reduction could also attenuate inflammation, reinforce cancer immunity, provide resistance to infections, and protect against liver pathologies. In this review, we question the relevance of this protein under normal physiology. We propose that PCSK9 is an important, but nonessential, modulator of cholesterol metabolism and immunity, and that its pathogenicity results from its chronic overexpression.

Proprotein convertase subtilisin/kexin-type 9 (PCSK9) is a member of the proprotein convertase endoproteinase family. Following its ribosomal synthesis, it undergoes autoproteolytic maturation and produces an enzymatically inactive complex between the mature protein with the cleaved propeptide which traffics to the extracellular space, where it binds to the EGF-A domain of the LDL receptor (LDLR), undergoes endocytosis with it and prevents the LDLR from being recycled by directing it towards lysosomes where it is degraded. By preventing LDLR recycling, PCSK9 decreases LDLR cell surface density which leads to an increase in LDL blood levels. Thus, PCSK9 became a prominent and novel target for the development of new treatments of hypercholesterolemia. Following the FDA approval (2015) of monoclonal antibodies that block PCSK9 from interacting with LDLR, it was suggested to selectively inhibit PCSK9 translation by directly binding small molecules to the ribosome RNA in the ribosome exit channel, inducing conformational change which inhibits the elongation of PCSK9 and stalling it in the exit channel. That mechanism was recently demonstrated by several structural studies and deposited in the Protein Data Bank (PDB).We picked from literature 59 molecules that act by the ribosomal stalling mechanism and diluted them by 59,000 molecules picked randomly on the basis of major similarities to these actives ('applicability domain'). We docked that set to six PDB structures in order to identify the one that distinguishes best between the actives and the expected inactives. That structure, 6OLE, was used to dock (on two docking levels) 3 million molecules from which only 17 could best fit strict geometry requirement together with good binding energy. We could get 9 out of these 17 candidates, and those were sent for in vitro testing. Five compounds were rejected due to their negative effects by 100mM in a 24-hour incubation with Huh7 cells. Of the remaining four, one compound (Z-023) reduced PCSK9 level in 24-h spent medium by nearly 60% (p < 0.01) and significantly reduced secreted PCSK9 by 42% and 64% at 100 μM and 128 μM, respectively. However, over a 2-h period of time. Z-023 affected 50% inhibition (IC50 = 33.7 μM) and 90% inhibition (IC90 = 116.4 μM). A half maximum viability (CC50) of 160.2 μM was derived from an MTS assay, with a calculated Selectivity Index CC50/IC50 = 4.8. Two other non-toxic compounds, Z-665 and Z-855, could be efficacious anti-PCSK9 anti-secretagogues as measured by cell confluence and mortality with low concentrations of 25μM, and the efficacy of these two compounds at 10 μM was evaluated using the '24 h incubation-2 h secretion' protocol. The PCSK9 level in spent media was reduced by 66.1% with -665 (p = 0.0022) and 50.6% with Z-855 (p = 0.011).

Isoquercetin and quercetin are secondary metabolites found in a variety of plants, including edible ones. Isoquercetin is a monoglycosylated derivative of quercetin. When ingested, isoquercetin accumulates more than quercetin in the intestinal mucosa where it is converted to quercetin; the latter is absorbed into enterocytes, transported to the liver, released in circulation, and distributed to tissues, mostly as metabolic conjugates. Physiologically, isoquercetin and quercetin exhibit antioxidant, anti-inflammatory, immuno-modulatory, and anticoagulant activities. Generally isoquercetin is less active than quercetin in vitro and ex vivo, whereas it is equally or more active in vivo, suggesting that it is primarily a more absorbable precursor to quercetin, providing more favorable pharmacokinetics to the latter. Isoquercetin, like quercetin, has shown broad-spectrum antiviral activities, significantly reducing cell infection by influenza, Zika, Ebola, dengue viruses among others. This ability, together with their other physiological properties and their safety profile, has led to the proposition that administration of these flavonols could prevent infection by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), or arrest the progression to severity and lethality of resulting coronavirus disease of 2019 (Covid-19). In silico screening of small molecules for binding affinity to proteins involved SARS-CoV-2 life cycle has repeatedly situated quercetin and isoquercetin near to top of the list of likely effectors. If experiments in cells and animals confirm these predictions, this will provide additional justifications for the conduct of clinical trials to evaluate the prophylactic and therapeutic efficacy of these flavonols in Covid-19.

Abstract Objective Circulating Proprotein convertase subtilisin/kexin type 9 (PCSK9) captured the scientific community's attention as powerful target to fight against high serum cholesterol and its associated adverse consequences. Despite the well-described role of PCSK9 in impairing the recycling of low-density lipoprotein receptor (LDLR) on hepatocytes, its intracellular importance in metabolism modulations remain largely unexplored. Here, we describe a novel intracellular function of PCSK9 in hepatocyte metabolism and in liver regeneration. Methods A surgical model of partial hepatectomy (PH) was used to induce liver cell proliferation and serological and histological lipo- and glyco-metabolic perturbations were investigated in PCSK9 knockout and wild-type mice before and after PH. Mitochondrial bioenergetic level, compartmental architecture as well as intracellular localization and function of PCSK9 were further analyzed in vitro on murine primary isolated hepatocytes and PCSK9 lentiviral knockdown human liver cancer cell lines. Results Loss of PCSK9 expression led to a basal higher mitochondrial bioenergetic status in hepatocytes, characterized by a profound remodeling of mitochondrial architecture. Livers from PCSK9 knockout mice displayed a diffuse oxidative stress and a significant upregulation of cellular detoxification and superoxide radicals removal genes induced by the activation of c-Jun N-terminal kinase (JNK) pathway before PH. PCSK9 deficient mice showed a primed compensatory hepatic hyperplasia after PH, accompanied by an earlier transient regeneration-associated steatosis due to a higher LDLR expression and cholesterol uptake, with an increased β-oxidation, gluconeogenesis and glycolysis rate. Tetramethylrhodamine ethyl ester staining of isolated hepatocytes and liver cancer PCSK9 knockdown clones revealed a significantly reduced mitochondrial membrane potential when compared to controls. Confocal live-cell imaging and proteins immunoprecipitation showed respectively a mitochondrial recruitment of PCSK9 in proliferating cells and its interaction with mitochondrial membrane carriers and chaperons. Conclusion Despite the role played by circulating PCSK9 in regulating systemic cholesterol levels, our data shed light on its intracellular impact on mitochondrial architecture, membrane polarization and related metabolic perturbations in compartmental bioenergetics.

Individuals harboring the loss-of-function (LOF) proprotein convertase subtilisin/kexin type 9 Gln152His variation (PCSK9Q152H) have low circulating low-density lipoprotein cholesterol levels and are therefore protected against cardiovascular disease (CVD). This uncleavable form of proPCSK9, however, is retained in the endoplasmic reticulum (ER) of liver hepatocytes, where it would be expected to contribute to ER storage disease (ERSD), a heritable condition known to cause systemic ER stress and liver injury. Here, we examined liver function in members of several French-Canadian families known to carry the PCSK9Q152H variation. We report that PCSK9Q152H carriers exhibited marked hypocholesterolemia and normal liver function despite their lifelong state of ER PCSK9 retention. Mechanistically, hepatic overexpression of PCSK9Q152H using adeno-associated viruses in male mice greatly increased the stability of key ER stress-response chaperones in liver hepatocytes and unexpectedly protected against ER stress and liver injury rather than inducing them. Our findings show that ER retention of PCSK9 not only reduced CVD risk in patients but may also protect against ERSD and other ER stress-driven conditions of the liver. In summary, we have uncovered a cochaperone function for PCSK9Q152H that explains its hepatoprotective effects and generated a translational mouse model for further mechanistic insights into this clinically relevant LOF PCSK9 variant.

Soluble low-density lipoprotein receptor (sLDLR) is the circulating ectodomain of transmembrane LDLR. Its blood level strongly correlates with that of triglycerides (TG). This correlation has eluded satisfactory explanation. Hypertriglyceridemia and shedding of the ectodomain of many transmembrane receptors often accompany inflammatory states. The shedding mostly occurs through cleavage by a disintegrin-and-metalloproteinase-17 (ADAM-17), an enzyme activated by inflammation. It reduces the cellular uptake of TG-loaded lipoproteins, causing their accumulation in circulation; hence the correlation between plasma sLDLR and TG. Soluble LDLR could become a new surrogate marker of inflammation.

Recent evidence suggests that proprotein convertase subtilisin/kexin type 9 (PCSK9), a downmodulator of cellular uptake of blood cholesterol, also negatively impacts host immune response to microbial infection. In this study, we investigated whether carrying the loss-of-function (LOF) rs562556 (c.1420 A > G; p.I474 V) PCSK9 single nucleotide polymorphism (SNP) affected the outcome of severe malaria in children. Archival DNA of a cohort of 207 Malian children suffering from severe malaria was genotyped for the rs562556 SNP. Sixty-four children were either heterozygous or homozygous for the minor G allele (carriers); 143 children were homozygous for the common A allele (noncarriers). Among carriers, there was one mortality case (1.6%), compared to 15 cases (10.5%) among noncarriers (p=0.0251), suggesting that the G allele is associated with better survival in severe malaria. Intriguingly, this allele did not negatively segregate with any of the clinical symptoms linked to mortality in this cohort. Studies are needed to determine whether PCSK9 inactivation promotes a protective immune response to malaria infection.

Help-seeking for mental disorders is a complex process, which includes different temporary stages, and in which the motivational variables play an especially relevant role. However, there is a lack of instruments to evaluate in depth both the temporary and motivational variables involved in the help-seeking process. This study aims to analyse in detail these two sets of variables, using a specific instrument designed for the purpose, to gain a better understanding of the process of treatment seeking.A total of 152 patients seeking treatment in mental health outpatient clinics of the NHS were individually interviewed: 71 had Obsessive-Compulsive Disorder, 21 had Agoraphobia, 18 had Major Depressive Disorder), 20 had Anorexia Nervosa, and 22 had Cocaine Dependence. The patients completed a structured interview assessing the help-seeking process. Disorder severity and quality of life was also assessed.The patients with agoraphobia and with major depression took significantly less time in recognising their mental health symptoms. Similarly, patients with major depression were faster in seeking professional help. Motivational variables were grouped in 3 sets: motivators for seeking treatment, related to the negative impact of symptoms on mood and to loss of control over symptoms; motivators for delaying treatment, related to minimisation of the disorder; and stigma-associated variables.The results support the importance of considering the different motivational variables involved in the several stages of the help-seeking process. The interview designed to that end has shown its usefulness in this endeavour.La búsqueda de ayuda profesional por enfermedad mental es un proceso complejo, con etapas y momentos temporales diferentes, en el que desempeñan un papel especialmente relevante los aspectos motivacionales. Sin embargo, no hay instrumentos de evaluación que permitan valorar tanto las variables temporales como las motivacionales. El objetivo de este estudio es ofrecer información detallada sobre ambos conjuntos de variables, mediante un instrumento específicamente diseñado para ello, de tal manera que se pueda comprender mejor el proceso de búsqueda de tratamiento.Participaron 152 pacientes ambulatorios que habían solicitado ayuda profesional en una unidad de salud mental del SNS. Los diagnósticos principales fueron: trastorno obsesivo-compulsivo (n = 71), agorafobia (n = 21), trastorno depresivo mayor (n = 18), anorexia nerviosa (n = 20) y dependencia a cocaína (n = 22). Los pacientes fueron evaluados mediante una entrevista estructurada, específicamente diseñada para el estudio. Asimismo, se obtuvieron datos sobre gravedad y calidad de vida.Los pacientes con agorafobia y depresión mayor tardaron menos en reconocer los síntomas que los pacientes de los otros grupos. Asimismo, los pacientes con depresión mayor demoraron menos en solicitar ayuda profesional. Las variables motivacionales se agruparon en 3 conjuntos: motivos de consulta, relacionados con el malestar y la falta de control; motivos de demora de la consulta, relacionados con la minimización del problema; y motivos asociados al estigma.Los resultados indican la necesidad de valorar las distintas variables motivacionales implicadas en las diferentes etapas del proceso de búsqueda de ayuda profesional. La entrevista que presentamos ha mostrado ser útil para ello.

Aim Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) is a hepatic secretory protein which promotes the degradation of low-density lipoprotein receptors leading to reduced hepatic uptake of plasma cholesterol. Non-synonymous single-nucleotide polymorphisms in its gene have been linked to hypo-or hyper-cholesterolemia, depending on whether they decrease or increase PCSK9 activity, respectively. Since the proliferation and the infectivity of Plasmodium spp. partially depend on cholesterol from the host, we hypothesize that these PCSK9 genetic polymorphisms could influence the course of malaria infection in individuals who carry them. Here we examined the frequency distribution of one dominant (C679X) and two recessive (A443T, I474V) hypocholesterolemic polymorphisms as well as that of one recessive hypercholesterolemic polymorphism (E670G) among healthy and malaria-infected Malian children. Methods Dried blood spots were collected in Bandiagara, Mali, from 752 age, residence and ethnicity-matched children: 253 healthy controls, 246 uncomplicated malaria patients and 253 severe malaria patients. Their genomic DNA was extracted and genotyped for the above PCSK9 polymorphisms using Taqman assays. Associations of genotype distributions and allele frequencies with malaria were evaluated. Results The minor allele frequency of the A443T, I474V, E670G, and C679X polymorphisms in the study population sample was 0.12, 0.20, 0.26, and 0.02, respectively. For each polymorphism, the genotype distribution among the three health conditions was statistically insignificant, but for the hypercholesterolemic E670G polymorphism, a trend towards association of the minor allele with malaria severity was observed (P = 0.035). The association proved to be stronger when allele frequencies between healthy controls and severe malaria cases were compared (Odd Ratio: 1.34; 95% Confidence Intervals: 1.04-1.83); P = 0.031). Conclusions Carriers of the minor allele of the E670G PCSK9 polymorphism might be more susceptible to severe malaria. Further investigation of the cholesterol regulating function of PCSK9 in the pathophysiology of malaria is needed.

SCOPE:Hepatic LDL receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9) regulate the clearance of plasma LDL-cholesterol (LDL-C): LDLR promotes it, and PCSK9 opposes it. These proteins also express in pancreatic β cells. Using cultured hepatocytes, we previously showed that the plant flavonoid quercetin-3-glucoside (Q3G) inhibits PCSK9 secretion, stimulated LDLR expression, and enhanced LDL-C uptake. Here, we examine whether Q3G supplementation could reverse the hyperlipidemia and hyperinsulinemia of mice fed a high-cholesterol diet, and how it affects hepatic and pancreatic LDLR and PCSK9 expression.METHODS AND RESULTS:For 12 weeks, mice are fed a low- (0%) or high- (1%) cholesterol diet (LCD or HCD), supplemented or not with Q3G at 0.05 or 0.1% (w/w). Tissue LDLR and PCSK9 is analyzed by immunoblotting, plasma PCSK9 and insulin by ELISA, and plasma cholesterol and glucose by colorimetry. In LCD-fed mice, Q3G has no effect. In HCD-fed mice, it attenuates the increase in plasma cholesterol and insulin, accentuates the decrease in plasma PCSK9, and increases hepatic and pancreatic LDLR and PCSK9. In cultured pancreatic β cells, however, it stimulates PCSK9 secretion.CONCLUSION:In mice, dietary Q3G could counter HCD-induced hyperlipidemia and hyperinsulinemia, in part by oppositely modulating hepatic and pancreatic PCSK9 secretion.

Purpose of review The nine members of the proprotein convertase family play major physiological roles during development and in the adult, and their dysregulation leads to various diseases. The primary objective of this article is to review recent findings on the clinical importance of some of these convertases concentrating mostly on PCSK9, the ninth member of the convertase family. This includes the transcriptional and translational regulation of PCSK9, its ability to enhance the degradation of LDL receptor (LDLR), and the implication of PCSK9 in inflammation and sepsis. Recent findings PCSK9 levels are upregulated by E2F1 and reduced by specific miRNAs and by Annexin A2 that bind the 3’ end of its mRNA. The implication of the LDLR in the clearance of pathogenic bacterial debris in mice and human puts in perspective a new role for PCSK9 in the regulation of sepsis. The specific implication of the LDLR in the clearance of Lp(a) is now confirmed by multiple studies of PCSK9 inhibition in human cohorts. Summary Emerging data suggest that PCSK9 can be regulated at the transcriptional and translational levels by specific factors and miRNAs. The identification of a novel pocket in the catalytic domain of PCSK9 represents a harbinger for a new class of small inhibitor drugs. The implication of the LDLR in reducing the effects of bacterially induced sepsis has been supported by both human and mouse data. Outcome studies confirmed the clinical importance of reducing PCSK9 levels. The present review puts in perspective new developments in the PCSK9 biology and its regulation of the LDLR. Video abstract http://links.lww.com/COL/A17

Context: Elevated circulating cholesterol-rich low-density lipoprotein (LDL) particles increase coronary artery disease risk. Cell-surface hepatic LDL receptors (LDLRs) clear 70% of these particles from circulation. The ectodomain of LDLR is shed into circulation, preventing it from removing LDL particles. The role that LDLR ectodomain shedding plays as a regulatory mechanism is unknown. Objective: We describe LDLR shedding via the relationships between circulating soluble LDLRs (sLDLRs) and serum lipoproteins, serum proprotein convertase subtilin/kexin type 9 (PCSK9; a negative regulator of LDLR), and clinical parameters in a white Canadian population. Design: Population-based, cross-sectional study. Settings: Clinical Research Center, The Ottawa Hospital, and Faculty of Medicine, University of Ottawa. Participants: Two hundred seventy-three white Canadians. Intervention: None. Main Outcome Measures: sLDLR measured by ELISA; serum lipids and PCSK9, PCSK9 genotypes, and clinical parameters from previous analyses. Results: sLDLRs correlated strongly with triglycerides (TG; r = 0.624, P < 0.0001) and moderately with LDL cholesterol (r = 0.384, P < 0.0001), and high-density lipoprotein cholesterol (r = -0.307, P = 0.0003). Only TG correlations were unaffected by PCSK9 variations. sLDLR levels were significantly elevated in those with TG >50th or LDL cholesterol >75th percentiles. Conclusions: Serum sLDLR levels correlate with several lipoprotein parameters, especially TG, and the presence of PCSK9 loss-of-function variants alters sLDLR levels and correlations, except for TG. Ectodomain LDLR shedding has a role in LDL metabolism, distinct from PCSK9, with interplay between these two pathways that regulate cell-surface LDLRs. Findings suggest alteration of LDLR shedding could emerge as a target to treat dyslipidemia.

Q3G is a natural derivative of quercetin and is already widely used in various foods and drinks. Our results clearly demonstrated that Q3G exerts antiviral activity against ZIKV in both tissue culture and knockout mice, and that post-exposure in vivo treatment with Q3G could have a beneficial effect. In the future, Q3G should be tested in human cell lines (such as Huh-7, HeLa, or K048, a fetal brain neural stem cell line) to provide further data supporting its potential efficacy in humans; in addition, live viral loads or viremia should be tested in treated animals to supplement the survival results observed in this study. Although the treatment regimens will need to be further optimized (i.e., dosage, frequency of treatment, and administration routes), our results support the results of Q3G efficacy studies in nonhuman primates against ZIKV infection. Further studies will also be needed to investigate the mechanism of Q3G antiviral action, in order to obtain valuable insights into the design of novel targets for antiviral therapeutics in the future.

Context:Proprotein convertase subtilisin kexin 9 (PCSK9) mediates degradation of the low-density lipoprotein receptor (LDLR), thereby increasing plasma low-density lipoprotein cholesterol (LDL-C). Variations in the PCSK9 gene associated with loss of function (LOF) of PCSK9 result in greater expression of hepatic LDLR, lower concentrations of LDL-C, and protection from cardiovascular disease (CVD). Apolipoprotein-B (apoB) remnants also contribute to CVD risk and are similarly cleared by the LDLR. We hypothesized that PCSK9-LOF carriers would have lower fasting and postprandial remnant lipoproteins on top of lower LDL-C.Objective:To compare fasting and postprandial concentrations of triglycerides (TGs), total apoB, and apoB48 as indicators of remnant lipoprotein metabolism in PCSK9-LOF carriers with those with no PCSK9 variants.Design:Case-control, metabolic study.Setting:Clinical Research Center of The Ottawa Hospital.Participants:Persons with one or more copies of the L10ins/A53V and/or I474V and/or R46L PCSK9 variant and persons with no PCSK9 variants.Intervention:Oral fat tolerance test.Main Outcomes Measures:Fasting and postprandial plasma TG, apoB48, total apoB, total cholesterol, and PCSK9 were measured at 0, 2, 4, and 6 hours after an oral fat load.Results:Participants with PCSK9-LOF variants (n = 22) had reduced fasting LDL-C (-14%) as well as lower fasting TG (-21%) compared with noncarrier controls (n = 23). LOF variants also had reduced postprandial total apoB (-17%), apoB48 (-23%), and TG (-18%). Postprandial PCSK9 declined in both groups (-24% vs -16%, respectively).Conclusions:Participants carrying PCSK9-LOF variants had attenuated levels of fasting and postprandial TG, apoB48, and total apoB. This may confer protection from CVD and further validate the use of PCSK9 inhibitors to lower CVD risk.

Objective: Low-density lipoprotein receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9) are opposing regulators of plasma LDL-cholesterol levels. The PCSK9 gene exhibits many single or compound polymorphisms within or among mammalian species. This is case between the SPRET/EiJ (SPRET) and C57BL/6J (B6) mouse strains. We examined whether these polymorphisms could be associated with differential expression and activity of their respective PCSK9 molecules.Methods: Liver expression of LDLR and PCSK9 transcripts were assessed by RT-PCR, and that of their corresponding proteins by immunoblotting. Purified recombinant PCSK9 proteins were assayed for their ability to degrade LDLR. Pcsk9 gene proximal promoters were tested for activation of a luciferase reporter gene.Results: SPRET and B6 mice carried comparable levels of plasma cholesterol in spite of the fact that SPRET mice expressed less PCSK9 and more LDLR in liver. There were indels and single-base differences between their Pcsk9 cDNA and promoter sequences. Ex vivo, SPRET PCSK9 protein was less secreted but was more active at degrading LDLR. Its gene promoter was more active at driving expression of the luciferase reporter.Conclusions: Collectively, these results suggest that, compared to the B6 mouse, the SPRET mouse may represent an example of absence of direct correlation between PCSK9 and cholesterol levels in plasma, due to genetic variations leading to reduced secretion of PCSK9 associated with greater LDLR-degrading activity. (C) 2016 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).