Which enzyme hydrolyzes triglycerides and phospholipids from HDL, and lipids in VLDL and IDL?

• A. Endothelial lipase
• B. Hepatic lipase
• C. Lipoprotein lipase
• D. CETP

Answer: (B)

Understanding how lipases remodel lipoproteins is being tested here. Hepatic lipase, anchored to the liver endothelium, hydrolyzes triglycerides and phospholipids on HDL particles and also acts on triglycerides in VLDL and IDL remnants. This dual action helps reduce HDL’s triglyceride and phospholipid content while processing VLDL/IDL remnants, fitting the description in the question. In contrast, lipoprotein lipase mainly targets triglycerides in chylomicrons and VLDL within capillaries; endothelial lipase mainly hydrolyzes phospholipids on HDL; CETP transfers cholesteryl esters and triglycerides between lipoproteins rather than hydrolyzing them. So hepatic lipase best explains the hydrolysis across HDL and the remnant lipoproteins described.