Fenofibrate treatment increases human serum proprotein convertase subtilisin kexin type 9 levels

Over the past several years, proprotein convertase subtilisin kexin type 9 (PCSK9) has gained significant attention as a key regulator of serum LDL-cholesterol (LDL-C) levels. In humans, gain-of-function mutations in PCSK9 cause a form of familial hypercholesterolemia, whereas loss-of-function mutations result in significantly decreased LDL-C and cardiovascular risk. Our laboratory was the first to demonstrate that atorvastatin increases PCSK9 serum levels, an observation that has since been confirmed by at least two other groups. In light of these observations, we studied the effect of another common lipid-lowering medication, fenofibrate, on circulating PCSK9 protein levels in patients treated with fenofibrate or placebo for 12 weeks. We observed that fenofibrate (200 mg per day) significantly increased circulating PCSK9 levels by 25% compared with baseline. Placebo treatment, in comparison, had no effect on PCSK9 levels. Interestingly, fenofibrate-induced increases in serum PCSK9 levels were highly correlated with fenofibrate-induced changes in HDL-C and triglyceride levels, as well as with fenofibrate-induced changes in LDL-C levels. These results suggest an explanation for why fibrates do not achieve as much LDL-C lowering as might otherwise be expected and indicate that the addition of a PCSK9 inhibitor to fibrate therapy may result in additional beneficial LDL-C lowering.