Lipoproteins

1. Lipoproteins • Clusters of lipids associated with proteins that serve as transport vehicles for lipids in the lymph and blood

2. Lipoproteins • Distinguished by size and density • Each contains different kinds and amounts of lipids and proteins • The more lipid, the lower the density • The more protein, the higher the density

3. Lipoproteins • Chylomicrons • VLDL – Very low density lipoprotein • IDL – Intermediate density lipoprotein • LDL – Low density lipoprotein • HDL – High density lipoprotein

4. Lipoproteins • Distinguished by size and density • Each contains different kinds and amounts of lipids and proteins • The more lipid, the lower the density • The more protein, the higher the density

5. The Origins & Major Functions of Lipoproteins

6. Functions of Chylomicrons • Made by intestinal cells • Most of lipid is triglyceride • Little protein • ApoA-I, ApoA-II, ApoB-48, ApoC • Deliver fatty acids via lipoprotein lipase

7. Chylomicron remnants • Lipoprotein particle that remains after a chylomicron has lost most of its fatty acids • Taken up by liver • Contents reused or recycled

8. Further Delivery of Lipids in Body • Liver • Synthesizes & metabolizes lipids • “Central command center” for relation of lipid metabolism • Makes additional lipoproteins

9. Very-Low-Density Lipoproteins (VLDL) • Made by liver • Contains large amounts of triglyceride • Delivers fatty acids to cells • More dense than chylomicrons • A bit more protein (8%) • ApoB-100, ApoC, ApoE

10. Intermediate-Density Lipoproteins (IDL) • Lipoprotein that results from loss of fatty acids from VLDL • Major lipid is cholesterol esters • Proteins similar to VLDL but greater percentage (15%) • ApoB-100, ApoC, ApoE • Taken up by liver or remain in circulation • Converted to low-density lipoproteins (LDL)

11. Low-Density Lipoproteins (LDL) • “Bad” cholesterol; major lipid in LDL • Delivers cholesterol from liver to cells • Cell membranes • Hormone production • Protein (21%) • ApoB-100 • Binds to specific LDL receptor • LDL receptors • Membrane-bound proteins that bind LDL, causing them to be taken up & dismantled

12. Increase LDL SFAs Trans fatty acids High cholesterol intake Lifestyle factors Genetics Decrease LDL High PUFA diet Ω-3 fatty acids Dietary fiber Lifestyle factors Genetics Effect of Diet on LDL Concentrations

13. High-Density Lipoproteins (HDL) • “Good” cholesterol; major lipid is phospholipid • Lipoprotein made by liver that circulates in the blood to collect excess cholesterol from cells • Lowest lipid-to-protein ratio • Protein (50%) • ApoA, ApoC, ApoE • Reverse cholesterol transport • Salvage excess cholesterol from cells • Transported back to liver

14. Effects of Diet on HDL Concentration • What raises HDL? • Uncertain if low carbohydrate diets offer protection • High MUFA intake • Moderate alcohol consumption • Lifestyle factors • Genetic factors influence HDL

15. Tangier Disease • Genetic disorder resulting in production of faulty HDL particles that cannot take up cholesterol from cells • High risk for developing cardiovascular disease

16. Properties of Plasma Lipoproteins

17. Lipids (%) in Plasma Lipoproteins

18. Cardiovascular disease (CVD) • General term for all diseases of the heart and blood vessels • Atherosclerosis is the main cause of CVD • Atherosclerosis leads to blockage of blood supply to the heart, damage occurs (coronary heart disease, CHD) • Cardio = heart • Vascular = blood vessels

19. Lipoproteins and cardiovascular disease (CVD) risk • LDL is positively associated with CVD • HDL is negatively associated with CVD

20. LDL and atherosclerosis

21. Recommended blood lipids • Total cholesterol: <200 mg/dL • LDL cholesterol: <130 mg/dL • HDL cholesterol: >35 mg/dL • Triglycerides: <200 mg/dL