1. Lipoproteins
A lipoprotein is a biochemical assembly that contains both proteins and lipids, bound to the proteins, which allow fats to move through the water inside and outside cells.
The proteins serve to emulsify the lipid molecules.
Many enzymes, transporters, structural proteins, antigens, adhesins, and toxins are lipoproteins.

2. Examples include the plasma lipoprotein particles classified under high-density (HDL) and low-density (LDL) lipoproteins.
Enable fats to be carried in the blood stream, the transmembrane proteins of the mitochondrion and the chloroplast, and bacterial lipoproteins

4. Apolipoproteins Embedded in the lipoprotein shell Three functions
1. Serve as recognition sites for cell-surface receptors; allowing cells to bind and ingest the lipoprotein.
2. Activate enzymes that will metabolize the lipoprotein
3. ↑ structural stability of the lipoprotein

5. Apolipoproteins
All lipoproteins that deliver lipids to peripheral tissues (nonhepatic tissues) contain apolipoprotein B-100 (Ex: VLDL, LDL)
All lipoproteins that transport lipids from peripheral tissues back to the liver contain apolipoprotein A-I (Ex: HDL)

6. Types of Lipoproteins lipoprotein classes
Classified according to density and electrophoresis migration
Lipoproteins differ in their sizes, density, weights, chemical composition and artherogenicity (association with heart disease )
lipoprotein classes
chylomicrons: take lipids from small intestine through lymph cells
very low density lipoproteins (VLDL)
intermediate density lipoproteins (IDL)
low density lipoproteins (LDL)
high density lipoproteins (HDL)

7. Lipoprotein Nomenclature and CompositionCM
VLDL
IDL
LDL
HDL
Major apoB apoB apoB apoB apoA-I
Protein
Major TG TG CE CE CE
Lipid
CM= chylomicron TG=triglyceride
VLDL= very low density lipoprotein CE= cholesteryl ester
IDL= intermediate density lipoprotein
LDL= low density lipoprotein
HDL= high density lipoprotein
Apo = apolipoprotein

9. Lipoprotein Profile
Cholesterol levels are measured in milligrams (mg) of cholesterol per deciliter (dL) of blood.
Desirable or optimal levels for adults with or without existing heart disease are:
Total cholesterol: Less than 200 mg/dL.
Low Density Lipoprotein (LDL) cholesterol: Less than 100 mg/dL.
High Density Lipoprotein (HDL): 40 mg/dL or higher.
Triglycerides: Less than 150 mg/dL.

10. Lipoproteins
The HDL and LDL levels in the blood can be used to assess ones risk for atherosclerosis.
High levels of HDL is considered good
This is why HDL is sometimes referred to as “good cholesterol”
> 40 mg/dL is good.
High levels of LDL is considered bad
This is why LDL is sometimes referred to as “bad cholesterol”
> 100 mg/dL is bad.

11. Hyperlipidemia can lead to disease
When there is too much cholesterol /LDL in body (because of diet and the rate at which the cholesterol is processed) it is deposited in arteries, including those of the heart, which can lead to narrowing of the arteries and heart disease.
Studies of people with heart disease have shown that lowering cholesterol/LDL reduces the risk for dying from heart disease, having a heart attack, or needing heart bypass surgery or angioplasty.

12. Low cholesterol/LDL levels in your blood help keep you healthy by preventing heart attacks and strokes. Therefore, maybe eating foods that are low in cholesterol may ultimately be able to lower your risk for these diseases.

13. Lipids Metabolism

14. Transport of Lipoproteins in the Body

15. Transport of fats: VLDL moves triglycerides from liver to tissues.
LDL transfers
cholesterol to
tissues from liver.
HDL carries
cholesterol from
tissues to liver.
Monoglycerides and fatty
acids are absorbed by
intestines - transported
as chylomicrons in lymph
system to blood.-Fat Blocker-Xenical (Alli)
Dietary fat

16. Chylomicrons Transports exogeneous ( dietary ) triglycerides
% by weight is triglycerides
Absent from fasting plasma
Removed from the plasma within 6 hours by the liver
Inadequate clearance produces a creamy layer on the plasma

17. Transport Chylomicrons – lipoproteins
Transport primarily triglycerides from the GI tract to the liver.
Travel through lymph and enter blood in chest
Travel through the heart and then body
Enzymes break off fatty acids from TG and deliver them to cells for energy or storage as TG
Chylomicron remnants are then delivered to the liver

18. Transport
In the liver
Liver breaks down remaining TG and remakes them!
Liver also makes cholesterol and other TG
These TG and cholesterol are packaged with proteins to make VLDL

19. VLDL (Very Low Density Lipoproteins)
Transports endogeneous triglycerides from liver to tissues
% by weight is triglycerides
Excess dietary carbohydrates are converted to triglycerides by the liver

20. VLDL (very low density lipoprotein)
Contain triglycerides (TGs) and some cholesterol
Account for nearly all TGs in the blood
Contain B-100
Deliver triglycerides from the liver to adipose tissues and muscles. TGs are hydrolyzed and removed by lipoprotein lipase. Results in free fatty acids for storage in adipose tissue or oxidation in cardiac tissue or skeletal muscle
Remnants of hydrolysis are IDL (intermediate density lipoproteins), which can be transported to liver or converted to LDL
High levels increases risk of pancreatitis

21. Transport VLDL enters blood
VLDL delivers cholesterol and fatty acids to needy cells
Density goes up as the fats leave the transport protein

22. LDL molecule

23. LDL (Low Density Lipoproteins )
Synthesized in the liver
Transports cholesterol from liver to the tissues
Formed from IDL, the remnants of VLDL
Makes the greatest contribution to coronary atherosclerosis
Oxidized LDL contributes to atherosclerotic plaque

24. Transport VLDL becomes LDL as it loses FA Low density lipoprotein
LDL is high in cholesterol
LDL circulates in blood delivering cholesterol to cells
LDLs (low density lipoproteins) transport cholesterol, triglycerides and phospholipids from the liver to other tissues.

25. Account for 60-70% of cholesterol in the blood Contains B-100
LDL cholesterol is sometimes called bad cholesterol.
High LDL cholesterol leads to a buildup of cholesterol in arteries. The higher the LDL level in your blood, the greater chance you have of getting heart disease.
Account for 60-70% of cholesterol in the blood
Contains B-100
Delivers cholesterol to peripheral tissues

26. Transport LDL “Bad” cholesterol
Contributes to plaques when cholesterol “falls off” the LDL and is deposited on artery walls
Plaques narrow arteries
Raises blood pressure
Increases risk of blood clots and heart attacks
Low Density Lipoproteins (LDL) – is made by the liver and is comprised of cholesterol that is delivered to the cells in the body
High levels of LDL is strongly correlated with heart disease

27. HDL (high density lipoprotein)
“Good cholesterol”
Contain cholesterol
Account for 20-30% of cholesterol in the blood
Some contain Apo I and Apo II
Apo I is cardioprotective
Transports cholesterol from the peripheral tissues back to the liver – promotes cholesterol removal
Antiatherogenic

28. Transport
HDL
HDL transports cholesterol and other lipids back to liver for disposal
Can pick up cholesterol from plaques
Good cholesterol
HDLs (high density lipoproteins) transport cholesterol and phospholipids back to the liver.
High Density Lipoproteins (HDL) - made by the liver and picks up cholesterol from the cells fro recycling or excretion
High levels of HDL is inversely correlated with heart disease
It is protective
HDL cholesterol is sometimes called good cholesterol.
HDL carries cholesterol from other parts of your body back to your liver. The liver removes the cholesterol from your body. The higher your HDL cholesterol level, the lower your chance of getting heart disease.

29. HDL ( High Density Lipoprotein )
Transports excess cholesterol from the tissues back to the liver ( reverse transport )
Synthesized in the liver and intestines
Composition
30% PHOSPHOLIPIDS
20% CHOLESTEROL
50% APOPROTEIN
The “good “ cholesterol
VLDL = Trig / 5

31. Lipid and Lipoprotein Population Distributions
Serum lipoprotein concentrations differ between adult men and women,
Primarily as a result of differences in sex hormone levels,
Women having, on average, higher HDL cholesterol levels and lower total cholesterol and triglyceride levels than men.
The difference in total cholesterol, however, disappears after menopause as estrogen decreases

32. Arteriosclerosis
Increased LDL and decreased HDL associated with increased plaque formation
1% decrease in LDL drops CHD risk 2%
Treatment to reduce LDL below 100 mg/dL is effective in the stabilization and sometimes regression of plaques

33. Peripheral vascular disease (PVD)
When plaque develops in arteries of the arms or legs
Coronary artery disease (CAD)
when it develops in the heart
Cerebrovascular disease (CVD)
when it develops in the vessels of the brain

34. Adult Reference Ranges For Lipids
ANALYTE
REFERENCE RANGE
Total cholesterol
mg/dL
HDL cholesterol
40-75 mg/dL
LDL cholesterol
mg/dL
Triglyceride
mg/dL

35. LDL = Total Cholesterol – HDL – Trig/5
LDL Methods
Friedewald calculation
Determine total cholesterol, total triglycerides and HDL as before
VLDL is estimated as triglycerides/5
400 mg/dl is the upper limit for TG
LDL = Total Cholesterol – HDL – Trig/5