Inhibition Of Proprotein Convertase Research Articles

Optimal use of lipid-lowering therapy after acute coronary syndromes: A Position Paper endorsed by the International Lipid Expert Panel (ILEP)

Atherosclerotic cardiovascular disease (ASCVD) and consequent acute coronary syndromes (ACS) are substantial contributors to morbidity and mortality across Europe. Much of these diseases burden is modifiable, in particular by lipid-lowering therapy (LLT). Current guidelines are based on the sound premise that with respect to low density lipoprotein cholesterol (LDL-C), “lower is better for longer”, and the recent data have strongly emphasized the need of also “the earlier the better”. In addition to statins, which have been available for several decades, the availability of ezetimibe and inhibitors of proprotein convertase subtilisin/kexin type 9 (PCSK9) are additional very effective approach to LLT, especially for those at very high and extremely high cardiovascular risk. LLT is initiated as a response to an individual’s calculated risk of future ASCVD and is intensified over time in order to meet treatment goals. However, in real-life clinical practice goals are not met in a substantial proportion of patients. This Position Paper complements existing guidelines on the management of lipids in patients following ACS. Bearing in mind the very high risk of further events in ACS, we propose practical solutions focusing on immediate combination therapy in strict clinical scenarios, to improve access and adherence to LLT in these patients. We also define an ‘Extremely High Risk’ group of individuals following ACS, completing the attempt made in the recent European guidelines, and suggest mechanisms to urgently address lipid-medicated cardiovascular risk in these patients.

Neutrophil-to-hepatocyte communication via LDLR-dependent miR-223-enriched extracellular vesicle transfer ameliorates nonalcoholic steatohepatitis.

Neutrophil infiltration around lipotoxic hepatocytes is a hallmark of nonalcoholic steatohepatitis (NASH); however, how these 2 types of cells communicate remains obscure. We have previously demonstrated that neutrophil-specific microRNA-223 (miR-223) is elevated in hepatocytes to limit NASH progression in obese mice. Here, we demonstrated that this elevation of miR-223 in hepatocytes was due to preferential uptake of miR-223-enriched extracellular vesicles (EVs) derived from neutrophils as well other types of cells, albeit to a lesser extent. This selective uptake was dependent on the expression of low-density lipoprotein receptor (LDLR) on hepatocytes and apolipoprotein E (APOE) on neutrophil-derived EVs, which was enhanced by free fatty acids. Once internalized by hepatocytes, the EV-derived miR-223 acted to inhibit hepatic inflammatory and fibrogenic gene expression. In the absence of this LDLR- and APOE-dependent uptake of miR-223-enriched EVs, the progression of steatosis to NASH was accelerated. In contrast, augmentation of this transfer by treatment with an inhibitor of proprotein convertase subtilisin/kexin type 9, a drug used to lower blood cholesterol by upregulating LDLR, ameliorated NASH in mice. This specific role of LDLR and APOE in the selective control of miR-223-enriched EV transfer from neutrophils to hepatocytes may serve as a potential therapeutic target for NASH.

Bempedoic Acid in the Treatment of Patients with Dyslipidemias and Statin Intolerance.

An elevated plasma low-density lipoprotein cholesterol (LDL-C) level is a well-established atherosclerotic cardiovascular disease (ACSVD) risk factor. Randomized studies with statins (alone or in combination with other lipid-lowering drugs) have demonstrated their clinical efficacy in lowering LDL-C. Several classes of new, non-statin agents have been successfully studied and used (e.g., ezetimibe and inhibitors of proprotein convertase subtilisin/kexin type 9 [i-PSCK9]). However, many high ACSVD risk patients remain at a high residual cardiovascular risk, with at least 10% being statin intolerant. Bempedoic acid (ETC-1002) is a new inhibitor of cholesterol synthesis that targets ATP citrate lyase (ACL). Importantly, ETC-1002 is only converted into an active form in the liver and is free of muscle side effects.Area Covered: Mechanism of action of ETC-1002, clinical pharmacology, completed clinical studies with bempedoic acid, lipid-lowering efficacy/safety issues, and recent meta-analyses of trials with ETC-1002.Expert Opinion: ETC-1002 has been extensively studied in phase I-III clinical studies in over 4000 individuals from different patient populations (statin intolerance, familial hypercholesterolemia, and high ACSVD risk patients), ETC-1002 has been demonstrated to have moderate cholesterol-lowering efficacy and a good safety profile at a dose of 180mg/day as a monotherapy and in combination with statins and ezetimibe. The ongoing study CLEAR Outcomes, with composite cardiovascular endpoints, will elucidate the role of bempedoic acid in the management of high ACSVD risk and statin-intolerant patients with hypercholesterolemia. Long-term safety data on bempedoic acid are needed to fully establish this agent in evidence-informed guidelines for managing of patients with dyslipidemias.

Berberine on the Prevention and Management of Cardiometabolic Disease: Clinical Applications and Mechanisms of Action.

Berberine is an alkaloid from several medicinal plants originally used to treat diarrhea and dysentery as a traditional Chinese herbal medicine. In recent years, berberine has been discovered to exhibit a wide spectrum of biological activities in the treatment of diverse diseases ranging from cancer and neurological dysfunctions to metabolic disorders and heart diseases. This review article summarizes the clinical practice and laboratory exploration of berberine for the treatment of cardiometabolic and heart diseases, with a focus on the novel insights and recent advances of the underlying mechanisms recognized in the past decade. Berberine was found to display pleiotropic therapeutic effects against dyslipidemia, hyperglycemia, hypertension, arrhythmia, and heart failure. The mechanisms of berberine for the treatment of cardiometabolic disease involve combating inflammation and oxidative stress such as inhibiting proprotein convertase subtilisin/kexin 9 (PCSK9) activation, regulating electrical signals and ionic channels such as targeting human ether-a-go-go related gene (hERG) currents, promoting energy metabolism such as activating adenosine monophosphate-activated protein kinase (AMPK) signaling pathway, modifying gut microbiota to promote transforming of berberine into its intestine-absorbable form, and interacting with non-coding RNAs via targeting multiple signaling pathways such as AMPK, mechanistic target of rapamycin (mTOR), etc. Collectively, berberine appears to be safe and well-tolerated in clinical practice, especially for those who are intolerant to statins. Knowledge from this field may pave the way for future development of more effective pharmaceutical approaches for managing cardiometabolic risk factors and preventing heart diseases.

Proprotein convertases blockage up-regulates specifically metallothioneins coding genes in human colon cancer stem cells

Despite continuous exertion made, colon cancer still represents a major health problem and its incidence continues being high worldwide. There is growing evidence in support of the cancer stem cells (CSCs) being central in the initiation of this cancer, and CSCs have been the focus of various studies for the identification of new ways of treatment. Lately, the proprotein convertases (PCs) were reported to regulate the maturation and expression of various molecules involved in the malignant phenotype of colon cancer cells, however, the identity of the molecules regulated by these serine proteases in CSCs is unknown. In this study, we used the general PCs inhibitor, the Decanoyl-RVKR-chloromethylketone (Decanoyl-RVKR-CMK) that inhibits all the PCs found in the secretory pathway, and analyzed its effect on CSCs using RNA-seq analysis. Remarkably, from the only 9 up-regulated genes in the human SW620-derived sphere-forming cells, we identified 7 of the 11 human metallothioneins, all of them localized on chromosome 16, and zinc related proteins as downstream effectors of the PCs. The importance of these molecules in the regulation of cell proliferation, differentiation and chemoresistance, and their reported potential tumor suppressor role and loss in colon cancer patients associated with worse prognosis, suggests that targeting PCs in the control of the malignant phenotype of CSCs is a new potential therapeutic strategy in colon cancer.

Analysis of steatosis biomarkers and inflammatory profile after adding on PCSK9 inhibitor treatment in familial hypercholesterolemia subjects with nonalcoholic fatty liver disease: A single lipid center real-world experience

Background and aimsNonalcoholic fatty liver disease (NAFLD) may be crucial in subjects with familial hypercholesterolemia (FH). We aimed to evaluate the effect of the inhibitors of proprotein convertase subtilisin/kexin type 9 (PCSK9-i) on steatosis biomarkers such as triglyceride-glucose index (TyG) and hepatic steatosis index (HSI) and analyse the role of TG/HDL in this population before and after adding-on PCSK9-i. Methods and resultsIn this observational study, we evaluated 26 genetically confirmed FH patients with NAFLD and an LDL-C off-target despite high-intensity statins plus ezetimibe. All patients added PCSK9-i treatment and obtained biochemical analysis and TyG and HSI evaluation at baseline and after six months of PCSK9-i. No difference of steatosis biomarkers was found after adding-on PCSK9-i therapy. In a secondary analysis, we divided the study population in two groups according to TG/HDL median value: high TG/HDL group (H-TG/HDL) and low TG/HDL group (L-TG/HDL). TyG and HSI were significantly lower in the L-TG/HDL than H-TG/HDL group (for TyG 9.05 ± 0.34 vs 9.51 ± 0.32; for HSI 38.43 ± 1.35 vs 41.35 ± 1.83, p value for both < 0.05). After six months of PCSK9-i therapy, TyG and HSI were significantly reduced in the L-TG/HDL group after PCSK9-i therapy (−7.5% and −8.4% respectively, p value for both < 0.05) and these biomarkers were lower compared to H-TG/HDL group (for TyG 8.37 ± 0.14 vs 9.19 ± 0.12; for HSI 35.19 ± 1.32 vs 39.48 ± 1.33, p value for both < 0.05). ConclusionIn conclusion, PCSK9-i therapy significantly ameliorate steatosis biomarkers in FH patients with low TG/HDL; our results appear to be consistent with a beneficial role of PCSK9-i on steatosis biomarkers in FH subjects with NAFLD.

Effect of alirocumab on incidence of atrial fibrillation after acute coronary syndromes: insights from ODYSSEY OUTCOMES

Abstract Background Atrial fibrillation (AF) is a marker of risk in patients presenting with acute coronary syndromes (ACS). The potential effect of inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9) on the incidence of AF is unknown. Methods The ODYSSEY OUTCOMES trial compared randomized treatment with the PCSK9 inhibitor alirocumab or placebo in patients with recent ACS and residual dyslipidaemia despite optimal statin therapy. The current analysis determined: 1) whether alirocumab treatment influenced incident AF; 2) whether a history of AF influenced the risk of major adverse cardiovascular events (MACE); and 3) whether there was interaction between AF at baseline and randomized treatment on MACE. AF was determined from the medical history and investigator reports of adverse events. Results Of 18,924 participants, 662 (3.5%) had a history of AF at randomization and 18,262 (96.5%) had no history of AF. Of the latter category, 499 (2.7%) had incident AF. Older age, randomization in South America or Eastern Europe, history of heart failure or myocardial infarction, and higher body mass index were factors associated with incident AF. Treatment with alirocumab or placebo did not influence incident AF (2.2% vs 2.6%, respectively; hazard ratio 0.90, 95% confidence interval 0.75–1.08; Figure). Patients with a history of AF had a greater burden of comorbidities, including cerebrovascular disease, peripheral artery disease, hypertension and heart failure; they also had higher rates of MACE (Table). There was no significant interaction between AF and randomized treatment on risk of MACE (P interaction=0.78) Conclusions Although treatment with alirocumab did not significantly modify the risk of incident AF after ACS in this analysis, future studies with more sensitive and systematic methods of ascertainment may be warranted. History of AF is a strong predictor of risk of recurrent MACE after ACS. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Sanofi, Regeneron Pharmaceuticals, Inc

Proprotein convertase subtilisin/kexin type 9 inhibition as the next statin?

Despite the wide use of statins and other LDL-cholesterol (LDL-C)-lowering therapies, atherosclerotic cardiovascular disease remains an important cause of mortality and morbidity. Here, we discuss efficacy, side effects and convenience of current and future therapies inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9). Clinical trials with mAbs administered every 2-4 weeks and small interfering RNAs given two to four times per year have consistently demonstrated substantial LDL-C-lowering (40-60%) and improved outcome when added to existing lipid-lowering therapies. Pleiotropic effects of PCSK9 inhibition are somewhat different from those observed with statin treatment as evidenced by reduced levels of triglycerides and lipoprotein(a) with no apparent effect on inflammatory markers in patients treated with PCSK9 inhibitors. Treatment with mAb and small interfering RNA are associated with a high-cost, however, small molecules and vaccines may improve cost and convenience if development of these are successful. PCSK9 inhibitors are currently considered to be an add-on therapy and whether these drugs will be used as stand-alone and/or as a first choice is dependent on clinical readouts from ongoing and future trials, real-world evidence, convenience and treatment costs.

Cleavage of the soluble (pro)renin receptor (sATP6AP2) in the placenta

IntroductionThe (pro)renin receptor (ATP6AP2) is cleaved and released as soluble ATP6AP2 (sATP6AP2). The sATP6AP2 is detected in plasma and urine and is elevated in women with gestational diabetes and preeclampsia. The source and cleavage pathway of sATP6AP2 in pregnancy is unknown. The syncytiotrophoblast is the major placental secretory layer and is in direct contact with maternal blood. Both FURIN and Site 1 protease (MBTPS1) cleave sATP6AP2 in non-placental cells. We postulated that ATP6AP2 was cleaved by FURIN and/or MBTPS1 and that sATP6AP2 is secreted by the placental syncytiotrophoblast. MethodsTerm primary trophoblast cells were transfected with FURIN siRNA, negative control siRNA or vehicle. In a separate experiment, primary trophoblasts were treated with a pro-protein convertase inhibitor (DEC-RVKR-CMK), an MBTPS1 inhibitor (PF 429242) or vehicle. Trophoblasts were left to spontaneously syncytialise before cells and supernatants were collected and intracellular and extracellular sATP6AP2 levels analysed by immunoblot.Results: sATP6AP2 is secreted by placental trophoblasts. Levels of intra and extra-cellular sATP6AP2 decrease with syncytialisation (P = 0.01 and P = 0.02, respectively), as do FURIN mRNA (P = 0.0003) and protein (P = 0.0007). FURIN siRNA decreased FURIN mRNA and protein levels (both P < 0.0001). Neither FURIN siRNA or PF 429242 affected sATP6AP2 levels. DEC-RVKR-CMK significantly decreased extracellular sATP6AP2 protein levels (P = 0.02). DiscussionSoluble ATP6AP2 is secreted by placental trophoblasts and levels decrease with syncytialisation. DEC-RVKR-CMK, a broad inhibitor of pro-protein convertases reduced extracellular sATP6AP2 levels, but FURIN siRNA and MBTPS1 inhibition had no effect. Hence, a convertase other than FURIN or MBTPS1 is most likely responsible for placental sATP6AP2 secretion.

Dyslipidaemias and Cardiovascular Disease: Focus on the Role of PCSK9 Inhibitors

Genetic, experimental and clinical studies have consistently confirmed that inhibition of Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) can result in significant lowering of LDL-C and two fully human PCSK9 monoclonal antibodies have received regulatory approval for use in highrisk patients. Co-administration of PCSK9 with statins has resulted in extremely low LDL-C levels with excellent short-term safety profiles. While results from Phase III clinical trials provided significant evidence about the role of PCSK9 inhibitors in reducing cardiovascular event rates, their impact on mortality remains less clear. PCSK9 inhibitor therapy can be considered for high-risk patients who are likely to experience significant cardiovascular risk reduction.

Perceptions and Barriers on the Use of PCSK9 Inhibitors in Heterozygous Familial Hypercholesterolemia

To evaluate the effectiveness, adverse reactions, and adherence to treatment of hypolipidemic inhibitors of proprotein convertase subtilisin/kexin type 9 (PCSK9is) in a context of real clinical practice.We present an observational, retrospective, descriptive, multicenter study of patients with hypercholesterolemia who began treatment with PCSK9is between January 2017 and December 2019, with a minimum treatment period of 3 months. The main variable we recorded was the frequency of cardiovascular events (cardiovascular death, myocardial infarction, stroke, coronary revascularization, and hospitalization for unstable angina) in patients treated with PCSK9is. We recorded patient demographic characteristics and cardiovascular risk factors at onset of treatment as well as LDL-C levels and their reductions at 3, 6, 12, and 24 months. We calculated adherence to treatment and recorded the adverse reactions during treatment.A total of 154 patients were studied, 64 (41.6%) of whom were treated with alirocumab and 90 (58.4%) with evolocumab. The initial dose of alirocumab was 75 mg every 14 days in 48 patients (75%) and 150 mg eery 14 days in 16 (25%). All patients who in the evolocumab group received a dose of 140 mg every 14 days. The mean (SD) basal LDL-C level was 159.6 (50.1) mg/dL, the level at 3 months was 87.9 (49.9) mg/dL (mean [SD] decrease, 44.5% [28.2%]), the level at 6 months was 86.7 (49.2) mg/dL (mean [SD] decrease, 46.3% [25.6%]), and the level at 12 months was 80.5 (41.4) (mean [SD] decrease, 48.9% [23.0%]). These values were maintained at 24 months (mean [SD], 80.3 [41.8] mg/dL; mean [SD] decrease, 47.9% [27.8%]). The percentage decrease of LDL-C for both drugs was approximately 50%, which was maintained until 24 months after treatment. Six patients (3.9%) presented with some cardiovascular event: acute myocardial infarction (2 [1.3%]), stroke (1 [0.65%]), coronary revascularization (1 [0.65%]), and hospitalization for unstable angina (2 [1.3%]). We did not see any adverse reactions related to PCSK9i treatment in 76.5% of patients. In the first 6 months, adherence to treatment with PCSK9is, measured as the possession ratio, was a mean (SD) of 99.4% (3.9%). In the rest of the study period (6–24 months), the mean (SD) adherence to treatment was 99.2% (4.7%).The frequency of cardiovascular events in patients treated with PCSK9is was low and occurred despite adequate adherence to treatment (100% possession ratio) with PCSK9is and concomitant treatment with other hypolipidemics. The effectiveness of PCSK9is is similar to that referred to in other published studies with PCSK9is, and this was maintained in the long term (24 months) with few adverse events, all of which were mild.

P0260CLINICAL PROFILE OF PATIENTS INITIATING EVOLOCUMAB IN SPANISH NEPHROLOGY UNITS: A RESTROSPECTIVE, OBSERVATIONAL STUDY IN CLINICAL PRACTICE (RETOSS-NEPHRO)

Abstract Background and Aims Cardiovascular disease is the primary cause of morbidity and mortality in patients with chronic kidney disease (CKD). Evolocumab is a monoclonal antibody that inhibits proprotein convertase subtilisin-kexin type 9 (PCSK9) and lowers serum low density lipoprotein cholesterol (LDL-C) levels. Evolocumab is indicated for adult patients with hypercholesterolaemia or mixed dyslipidaemia who are unable to reach LDL-C goals with the maximum tolerated dose of statin or are statin intolerant. This study was conducted to describe clinical characteristics, reasons for therapy initiation and treatment effects in patients treated with evolocumab in Spanish Nephrology units. Method Retrospective, observational, chart review of consecutive patients initiating evolocumab (Feb-2016 to Aug-2018) in 15 Spanish Nephrology Units. Patient characteristics, lipid modifying therapies and lipid profiles over time were retrospectively collected at 24 weeks pre- and 12±4 weeks post-evolocumab initiation. Results 60 patients were enrolled: 53.3% women; mean (SD) age, 56.9 (12.8) years; mean (SD) body mass index, 28.0 (4.7) kg/m2; 45.0% had familial hypercholesterolemia (FH) (5.0% homozygous, 23.3% heterozygous, 16.7% undetermined FH); from the total population, 35% were in primary prevention and 65.0% started evolocumab after previous Atherosclerotic Cardiovascular Disease [ASCVD]. Regarding renal function, mean (SD) eGFR was 62.6 (30.0) ml/min/1.73m2; 51.7% of patients had eGFR &amp;lt;60 ml/min/1.73m2 (CKD stage&amp;gt;2), 50.0% had proteinuria (&amp;gt;300 mg/g) and 10.0% had nephrotic syndrome. Other CV risk factors were hypertension (75.0%), diabetes (25.0%), and smoking (21.7%); 40.0% of patients were statin intolerant. At evolocumab initiation, 41.7% of patients were on a high intensity statin, 18.3% on moderate intensity statin and 50.0% were receiving ezetimibe. Mean (SD) LDL-C at evolocumab initiation was 179.7 (62.9) mg/dL (53.4% of patients with LDL-C≥160; 29.3% ≥190). Mean (SD) baseline HDL-C and total cholesterol were 48.5 (15.0) mg/dL and 273.1 (82.7) mg/dL, respectively. After 12 weeks, evolocumab resulted in LDL-C reductions of 60.1%, to a mean (SD) of 72.7 (80.3) mg/dL, with similar results observed in patients in primary/secondary prevention, with CKD stage &amp;gt;2/≤2 or with/without proteinuria. Conversely, patients with/without FH showed significant differences between their reductions (46.6% vs 76.6%, respectively, p=0.0276). At week 12, 90.0% of patients reached LDL-C levels &amp;lt;100 mg/dL, 70.0% &amp;lt;70 mg/dL, and 55.0% &amp;lt;55mg/dL, while eGFR levels and statin use remained stable. Conclusion In Spanish Nephrology Units, evolocumab was predominantly prescribed in patients with FH, ASCVD and/or CKD stage &amp;gt;2. Initial evolocumab use was aligned with ESC/EAS dyslipidaemia guidelines, but with higher baseline LDL-C levels than the recommended thresholds. After 12 weeks of evolocumab treatment, LDL–C levels were more than halved and the majority of patients achieved both the 2016 and 2019 EAS/ESC targets of LDL-C control.

Naturally Occurring PCSK9 Inhibitors.

Genetic, epidemiological and pharmacological data have led to the conclusion that antagonizing or inhibiting Proprotein convertase subtilisin/kexin type 9 (PCSK9) reduces cardiovascular events. This clinical outcome is mainly related to the pivotal role of PCSK9 in controlling low-density lipoprotein (LDL) cholesterol levels. The absence of oral and affordable anti-PCSK9 medications has limited the beneficial effects of this new therapeutic option. A possible breakthrough in this field may come from the discovery of new naturally occurring PCSK9 inhibitors as a starting point for the development of oral, small molecules, to be used in combination with statins in order to increase the percentage of patients reaching their LDL-cholesterol target levels. In the present review, we have summarized the current knowledge on natural compounds or extracts that have shown an inhibitory effect on PCSK9, either in experimental or clinical settings. When available, the pharmacodynamic and pharmacokinetic profiles of the listed compounds are described.

Metabolic effects of PCSK9 inhibition with Evolocumab in subjects with elevated Lp(a)

BackgroundEpidemiological studies substantiated that subjects with elevated lipoprotein(a) [Lp(a)] have a markedly increased cardiovascular risk. Inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) lowers both LDL cholesterol (LDL-C) as well as Lp(a), albeit modestly. Effects of PCSK9 inhibition on circulating metabolites such as lipoprotein subclasses, amino acids and fatty acids remain to be characterized.MethodsWe performed nuclear magnetic resonance (NMR) metabolomics on plasma samples derived from 30 individuals with elevated Lp(a) (> 150 mg/dL). The 30 participants were randomly assigned into two groups, placebo (N = 14) and evolocumab (N = 16). We assessed the effect of 16 weeks of evolocumab 420 mg Q4W treatment on circulating metabolites by running lognormal regression analyses, and compared this to placebo. Subsequently, we assessed the interrelationship between Lp(a) and 14 lipoprotein subclasses in response to treatment with evolocumab, by running multilevel multivariate regression analyses.ResultsOn average, evolocumab treatment for 16 weeks resulted in a 17% (95% credible interval: 8 to 26%, P < 0.001) reduction of circulating Lp(a), coupled with substantial reduction of VLDL, IDL and LDL particles as well as their lipid contents. Interestingly, increasing concentrations of baseline Lp(a) were associated with larger reduction in triglyceride-rich VLDL particles after evolocumab treatment.ConclusionsInhibition of PCSK9 with evolocumab markedly reduced VLDL particle concentrations in addition to lowering LDL-C. The extent of reduction in VLDL particles depended on the baseline level of Lp(a). Our findings suggest a marked effect of evolocumab on VLDL metabolism in subjects with elevated Lp(a).Trial registrationClinical trial registration information is registered at ClinicalTrials.gov on April 14, 2016 with the registration number NCT02729025.

SUN-580 PCSK9 and Lp(a): Association Between PCSK9 Level and Larger Apo(a) Isoform Size in African-Americans and Caucasians

Introduction: An elevated level of lipoprotein(a) [Lp(a)] is an independent causal risk factor for cardiovascular disease. Non-genetic factors do not appreciably influence Lp(a) levels due to a strong genetic control. However, inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) has been shown to reduce Lp(a) levels. The association of PCSK9 with Lp(a) level and its major genetic determinant—apolipoprotein(a) [apo(a)] size—is not fully understood. In this study, we assessed the relationship between PCSK9, Lp(a) level, apo(a) size, age, and race/ethnicity. Methods: Healthy Caucasian and African-American families were recruited from the general population (age range: 6–74 years, N=267). PCSK9 and Lp(a) levels were assayed enzymatically; apo(a) isoform and LPA allele sizes and isoform-specific Lp(a) levels were determined. Results: In all participants, PCSK9 levels differed significantly by race/ethnicity, age, and sex. Thus, the mean PCSK9 levels were significantly higher in African-Americans vs. Caucasians (104 ± 29 vs. 95 ± 30 ng/mL, respectively, p=0.020), in adults vs. children (102 ± 29 vs. 92 ± 31 ng/mL, respectively, p=0.001) and in females vs. males (103 ± 30 vs. 94 ± 29 ng/mL, respectively, p=0.007). PCSK9 levels were not associated with total plasma Lp(a) levels neither in all participants nor in ethnicity-specific analyses. However, PCSK9 levels were significantly and positively associated with isoform-specific Lp(a) levels carried by the larger apo(a) size in all subjects (r=0.139, p=0.0361). In race/ethnicity analyses, a significant association was seen for African-Americans (r=0.268, p=0.0199), but not for Caucasians. In contrast, there were no significant associations of PCSK9 with isoform-specific Lp(a) levels for the smaller apo(a) sizes in all participants nor in ethnic-specific analyses. Of note, PCSK9 levels were significantly negatively associated with the larger apo(a) isoform sizes in all participants (r=-0.139, p=0.0366). Although significant in both groups, heritability of PCSK9 level was higher in Caucasians than in African-Americans (47% vs. 22%, respectively). Conclusions: Among African-Americans, but not Caucasians, PCSK9 levels were associated with isoform-specific Lp(a) levels carried on larger, but not smaller, apo(a) sizes. The findings illustrate a diverging relationship of PCSK9 with isoform-specific Lp(a) levels.

Proteolytic activation of the epithelial sodium channel: role of pro‐protein convertases and prostasin

The epithelial sodium channel (ENaC) is essential for regulating renal sodium excretion. Cleavage of the γENaC subunit increases ENaC activity both in vitro and in vivo; however, the involved endogenous proteases remain ambiguous. This study investigates the mechanistic roles of the pro‐protein convertase (PCSK) family and the serine protease prostasin in proteolytic activation of ENaC.We used the M‐1 mouse collecting duct cell line that natively expresses functional ENaC channels for pharmacological inhibition studies with pro‐protein convertase inhibitor decanoyl‐RVKR‐chloromethyl ketone (dec‐RVKR‐cmk) and serine protease inhibitor camostat mesilate (CM). Knockout cell lines of prostasin and three PCSKs were generated with the CRISPR/Cas9 system in M‐1 cells. As an index of ENaC activity, amiloride‐sensitive short‐circuit current (ISC) and transepithelial voltage (VTE) was measured on polarized cells on transwell filter supports in Ussing chambers. γENaC membrane levels and cleavage were tested by western blotting of surface biotinylated M‐1 cells with an antibody against the C‐terminal of γENaC. All values are means SE, compared with students t‐test or ANOVA as appropriate.Pro‐protein convertase inhibition decreased the amiloride‐sensitive ISC in M‐1 cells compared with controls (25.9 1.9 μA, n=5, vs. 45.7 7.0 μA, n=6, p&lt;0.05). Similarly, serine protease inhibition decreased VTE (−34.5 7.8 mV, n=3, vs. −74.2 0.9 mV, n=3, p&lt;0.05) but ISC was not significantly lower (68.0 8.5, n=3, vs. 74.0 2.3, n=3, n.s.). Preliminary evidence suggests that although both inhibitors decreased membrane expression of γENaC, only serine protease inhibitor treatment reduced γENaC cleavage (n=1). Knockout of the Psck3 (furin) gene by CRISPR completely abolished ENaC activity, while knockout of Pcsk4, Pcsk7, and prostasin all showed decreased ENaC activity compared to wild‐type M‐1 cells. Knockout of PCSKs reduced γENaC surface expression, but only knockout of prostasin reduced γENaC cleavage.We propose that PCSKs are not directly involved in proteolytic ENaC activation. Both pharmacological inhibition and knockout of prostasin decreased ENaC activity and γENaC cleavage, thus suggesting a potential role in proteolytic ENaC activation.Support or Funding Information The Danish Medical Research Council

The Role of a Proprotein Convertase Inhibitor in Reactivation of Tumor-Associated Macrophages and Inhibition of Glioma Growth

Tumors are characterized by the presence of malignant and non-malignant cells, such as immune cells including macrophages, which are preponderant. Macrophages impact the efficacy of chemotherapy and may lead to drug resistance. In this context and based on our previous work, we investigated the ability to reactivate macrophages by using a proprotein convertases inhibitor. Proprotein convertases process immature proteins into functional proteins, with several of them having a role in immune cell activation and tumorigenesis. Macrophages were treated with a peptidomimetic inhibitor targeting furin, PC1/3, PC4, PACE4, and PC5/6. Their anti-glioma activity was analyzed by mass spectrometry-based proteomics and viability assays in 2D and 3D in vitro cultures. Comparison with temozolomide, the drug used for glioma therapy, established that the inhibitor was more efficient for the reduction of cancer cell density. The inhibitor was also able to reactivate macrophages through the secretion of several immune factors with antitumor properties. Moreover, two proteins considered as good glioma patient survival indicators were also identified in 3D cultures treated with the inhibitor. Finally, we established that the proprotein convertases inhibitor has a dual role as an anti-glioma drug and anti-tumoral macrophage reactivation drug. This strategy could be used together with chemotherapy to increase therapy efficacy in glioma.

Aloe-emodin exerts cholesterol-lowering effects by inhibiting proprotein convertase subtilisin/kexin type 9 in hyperlipidemic rats

Hyperlipidemia (HPL) characterized by metabolic disorder of lipids and cholesterol is one of the important risk factors for cardiovascular diseases. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a potent circulating regulator of LDL through its ability to induce degradation of the low-density lipoprotein cholesterol receptor (LDLR) in the lysosome of hepatocytes. Aloe-emodin (AE) is one of potentially bioactive components of Chinese traditional medicine Daming capsule. In this study we evaluated the HPL-lowering efficacy of AE in both in vivo and in vitro HPL models. High-fat diet-induced rats were treated with AE (100 mg/kg per day, ig) for 6 weeks. We found that AE administration significantly decreased the levels of total cholesterol (TC) and LDL in the serum and liver tissues. Moreover, AE administration ameliorated HPL-induced hepatic lipid aggregation. But AE administration did not significantly inhibit HMG-CoA reductase activity in the liver of HPL rats. A cellular model of HPL was established in human hepatoma (HepG2) cells treated with cholesterol (20 μg/mL) and 25-hydroxycholesterol (2 μg/mL), which exhibited markedly elevated cholesterol levels. The increased cholesterol levels could be reversed by subsequent treatment with AE (30 μM). In both the in vivo and in vitro HPL models, we revealed that AE selectively suppressed the sterol-regulatory element-binding protein-2 (SREBP-2) and hepatocyte nuclear factor (HNF)1α-mediated PCSK9 signaling, which in turn upregulated LDL receptor (LDLR) and promoted LDL uptake. This study demonstrates that AE reduces cholesterol content in HPL rats by inhibiting the hepatic PCSK9/LDLR pathway.

Research digest: next-generation lipoprotein therapeutics

Lowering plasma LDL cholesterol with statins, ezetimibe, and inhibitors of proprotein convertase subtilisin/kexin type 9 reduces the risk of atherosclerotic cardiovascular disease by up to 40%. A lingering question is whether the residual 60% can be further reduced by other lipid-modulating treatments. To this end, attention has turned to other lipoproteins with atherogenic potential, such triglyceride-rich lipoproteins and the insidious lipoprotein(a).

Intensification of lipid-lowering therapy in patients with acute coronary syndrome

Lipid metabolism disorders play a key role in determining cardiovascular risk. The level of low-density lipoprotein cholesterol is a significant factor in the pathophysiology of atherosclerosis and an indicator, the assessment of which reduces the risk of cardiovascular events. The prevalence of acute coronary syndrome in Russia remains at a high level. To date, the successful implementation and implementation of standards for the management of acute coronary syndrome has significantly reduced hospital mortality rates, however, secondary prevention issues remain relevant. Despite a wide range of lipid-lowering drugs, the use of which at maximum doses in acute coronary syndrome does not allow reaching the target levels of the lipid spectrum, the risk of developing repeated cardiovascular events remains high. Recently, a promising direction is the use of type 9 subtilisin/ kexin proprotein convertase inhibitors for the intensification of lipid-lowering therapy in patients with acute coronary syndrome. This article presents the clinical case of the successful use of one of the inhibitors of the proprotein convertase of subtilisin/kexin type 9, alirocoumab, in lowering low-density lipoprotein cholesterol and thereby reducing the risk of repeated cardiovascular events in a patient with acute coronary syndrome.