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Proprotein convertase subtilisin kexin type 9 (PCSK9) is a circulating protein that impairs LDL clearance by promoting the LDL receptor (LDLR) degradation. PCSK9 has emerged as a new pharmacological target for hypercholesterolemia, and different PCSK9 inhibitors are now evaluated in clinical trials. Here, we propose an overview of the clinical perspectives of PCSK9. First, we describe the clinical features of patients with PCSK9 mutations, and how these variations impact the cardiovascular risk. Then, we extensively discuss the potential role of circulating PCSK9 as a new biomarker of lipid metabolism. Indeed, many studies conducted in healthy and type 2 diabetic patients have tested the association of circulating PCSK9 with LDL-cholesterol as well as with multiple metabolic parameters. The overall picture of the clinical relevance of circulating PCSK9 is complicated by the effect of nutritional status and hypolipidemic drugs such as statins, fibrates, ezetimibe on plasma PCSK9 concentrations. Finally, we present a brief overview of the available therapeutic strategies to inhibit PCSK9.

Proprotein convertase subtilisin kexin/type 9 (PCSK9) is an inhibitor of the low density (LDL) lipoprotein receptor. Plasma PCSK9 is increased by fenofibrate and statins. Here, we determined how standard dose of statin and combined therapy with fenofibrate modulate PCSK9.Randomized, open-label cross-over study investigating the effect of fenofibrate (160 mg), atorvastatin (10 mg), and combination of both in patients with type 2 diabetes mellitus and atherogenic dyslipidemia. After the single administration of atorvastatin and fenofibrate for 6 weeks, patients received both for another 6 weeks. PCSK9, lipids and lipoproteins levels were determined at day 1, weeks 6, 9 and 12.Upon 6 weeks of treatment, atorvastatin decreased LDL-cholesterol by 30% (p0.001) and fenofibrate decreased triglyceride level by 31% (p0.01) and increased HDL-cholesterol by 13% (p0.05). Combination did not show further benefit. Atorvastatin increased PCSK9 by 24% at day 1 and by 14% at week 6 (por = 0.01). Fenofibrate increased PCSK9 by 26% at week 6 (por = 0.01), but had no effect at day 1. Three weeks of combination therapy increased PCSK9 by 42%, 6 weeks by 19% (por = 0.01). PCSK9 changes were not different between treatments over 6-week periods.Fenofibrate and atorvastatin increased circulating PCSK9 in diabetic patients, with no additive effect after 6 weeks of combined therapy.

International audience; OBJECTIVE: Proprotein convertase subtilisin/kexin type 9 (PCSK9) is highly expressed in the kidney, where its function remains unclear. In vitro data suggested that PCSK9 could impair the trafficking of the epithelial Na channel (ENaC). Here, we aimed at determining the consequences of PCSK9-deficiency on blood pressure, sodium balance and ENaC function in vivo in mice. METHODS: Blood pressure was measured using non-invasive tail-cuff system or radiotelemetry under basal conditions in male and female PCSK9(+/+) and PCSK9(-/-) mice, as well as in models of hypertension: l-NAME (2 mg/kg/day), angiotensin II (1 mg/kg/day) and deoxycorticosterone acetate (DOCA)-salt in male mice only. Plasma and urine electrolytes (Na(+), K(+), Cl(-)) were collected under basal conditions, after DOCA-salt and amiloride treatment. Renal expression of ENaC subunits was assessed by western blotting. RESULTS: PCSK9-deficiency did not alter both basal blood pressure and its increase in salt-insensitive (l-NAME) and salt-sensitive (Ang-II and DOCA-salt) hypertension models. Plasma PCSK9 concentrations were increased by 2.8 fold in DOCA-salt-induced hypertension. The relative expression of the cleaved, active, 30-kDa αENaC subunit was significantly increased by 32% in kidneys of PCSK9(-/-) mice under basal, but not under high-Na(+) diet or DOCA-salt conditions. Amiloride increased urinary Na(+) excretion to similar level in both genotypes, indicating that ENaC activity was not affected by PCSK9-deficiency. CONCLUSIONS: Despite an increase of cleaved αENaC under basal condition, PCSK9(-/-) mice display normal sodium balance and blood pressure regulation. Altogether, these data are reassuring regarding the development of PCSK9 inhibitors in hypercholesterolemia.

Objective Pro-protein convertase subtilisin/kexin type 9 (PCSK9) is a post-transcriptional inhibitor of LDL-receptor. In non-diabetic men, plasma PCSK9 levels were found to be inversely correlated with low-density lipoprotein (LDL) apolipoprotein B100 (apoB) fractional catabolic rate (FCR). Here, we aimed to determine the effect of type 2 diabetes on the association between plasma PCSK9 and FCR of LDL. Methods A kinetic study of LDL-apoB100, using stable isotopes, was performed in 38 individuals (20 men, 18 women) including 23 non-diabetic normolipidemic subjects and 15 patients with type 2 diabetes. Results In the non-diabetic group, plasma PCSK9 was positively correlated with LDL-C ( r =0.64, p =0.001), apoB ( r =0.67, p r =−0.61, p =0.002). In contrast, in type 2 diabetic patients, plasma PCSK9 was not associated with LDL-C, apoB and LDL-apoB FCR. However, the lack of association between PCSK9 and LDL-apoB FCR seemed to be limited to the patients with "uncontrolled" diabetes (HbA1c>7%) since a borderline significant negative correlation between PCSK9 and LDL FCR ( r =−0.70, p =0.08) was retrieved in patients with HbA1c≤7%. In multivariate analysis, LDL-apoB FCR was independently associated with PCSK9 ( p =0.001) and fasting glycaemia (log) ( p =0.030) in the non-diabetic population and with PCSK9 ( p =0.040) and HbA1c ( p =0.029) in diabetic patients. Conclusion Our data indicate that both PCSK9 and glycaemia are independent factors influencing LDL catabolism. Plasma PCSK9 influences significantly the catabolism of LDL-apoB100 in individuals without diabetes, but not in patients with uncontrolled type 2 diabetes. Thus, the influence of diabetes on LDL-apoB FCR catabolism may overwhelm the influence of PCSK9.