The interrelations between PCSK9 metabolism and cholesterol synthesis and absorption

Area of Science:

• Biochemistry
• Cardiovascular Medicine
• Pharmacology

Background:

• Limited research exists on the interplay between proprotein convertase subtilisin/kexin type 9 (PCSK9) metabolism, cholesterol synthesis, and absorption.
• Understanding these relationships is crucial for managing hypercholesterolemia.

Purpose of the Study:

• To investigate the interrelations between PCSK9 metabolism, cholesterol synthesis, and cholesterol absorption in hypercholesterolemic patients.
• To evaluate the impact of PCSK9-antibody treatment on these parameters, with or without prior lipid-lowering therapy.

Main Methods:

• A clinical trial involving 245 hypercholesterolemic patients.
• Measurement of serum lipids, PCSK9, lathosterol (synthesis marker), campesterol, and sitosterol (absorption markers) before and after PCSK9-antibody treatment.
• Analysis of patient subgroups based on lipid-lowering pretreatment (none, ezetimibe, statins, or combination).

Main Results:

• Circulating PCSK9 levels increased with more potent lipid-lowering pretreatment, highest in the ezetimibe + statin group.
• PCSK9-antibody treatment significantly reduced LDL-cholesterol, lathosterol, campesterol, and sitosterol.
• No significant changes were observed in noncholesterol sterol to cholesterol ratios, and pretreatment did not affect PCSK9-antibody efficacy on these sterols.

Conclusions:

• Inhibitors of cholesterol synthesis and absorption lead to increased circulating PCSK9.
• Elevated PCSK9 may contribute to the potent LDL-cholesterol reduction observed with PCSK9-antibodies following such pretreatment.
• PCSK9-antibody therapy does not alter the fundamental balance between cholesterol synthesis and absorption.