Chronic hepatitis C virus infection and lipoprotein metabolism

Table 1 Classification of circulating lipoproteins

Class name	Density (g/mL)	Diameter (nm)	% Protein	% Cholesterol (free cholesterol + cholesteryl ester)	% Phospholipids	% Triglycerides	% Free fatty acids
CM	< 0.95	100-1000	< 2	4-8	7-8	84-88	0
VLDL	0.950-1.006	30-80	7-10	20-25	18-20	50-55	1
IDL	1.006-1.019	25-50	10-18	29-45	22-27	25-31	1
LDL	1.019-1.063	18-28	20-25	45-58	20-28	10-15	1
HDL	1.063-1.210	5-15	33-57	17-40	26-46	3-15	0-6

HDL: High-density lipoprotein; CM: Chylomicron; IDL: Intermediate-density lipoprotein; VLDL: Very-low-density lipoprotein; LDL: Low-density lipoprotein.

Table 2 Properties and functions of major apolipoproteins

Name	Molecular weight (Da)	Origin	Lipoprotein association	Principal function
apo A-I	28016	Hepatocyte	HDL>>CM	Cofactor of LCAT
		Intestinal epithelial cell		Prostacyclin stabilizer
				Ligand of SR-B1
apo A-II	17414	Hepatocyte	HDL	Inhibits LCAT
		Intestinal epithelial cell		Inhibits HL
apo A-IV	31570	Intestinal epithelial cell	CM	(Activates LCAT?)
		(hepatocyte?)		(Activates CETP?)
apo B-48	241000	Intestinal epithelial cell (splicing variant of apo B-100)	CM and CM remnant	Formation of CM particle
apo B-100	545000	Hepatocyte	VLDL, IDL, and LDL	Formation of VLDL/LDL particle
				Ligand of LDL receptor
apo C-I	6600	Hepatocyte	CM, VLDL, IDL, and HDL	Inhibits CETP by altering the electric charge of HDL
apo C-II	8800	Hepatocyte	CM, VLDL, IDL, and HDL	Cofactor of LPL
apo C-III	8750	Hepatocyte	CM, VLDL, IDL, and HDL	Inhibits LPL and HL
				Promotes assembly and secretion of VLDL
apo C-IV		Hepatocyte	CM, VLDL, IDL, and HDL	Not specified
apo E	34100	Hepatocyte	CM, CM remnant, VLDL, IDL and HDL	Ligand of LDL receptor/LDL receptor-related protein
		Macrophage		Binds to HSPGs

HDLs: High-density lipoproteins; CMs: Chylomicrons; IDLs: Intermediate-density lipoproteins; VLDL: Very-low-density lipoprotein; LDLs: Low-density lipoproteins; HSPGs: Heparan sulfate proteoglycans.