Non-HDL Cholesterol and Apo B:To B or Not to B?

非高密度脂蛋白胆固醇与载脂蛋白 B：选用载脂蛋白 B吗？

Dr Richard Pang

3 November (Thursday) 2005

Symposium on Laboratory Medicine

To (measure apo) BTo (measure apo) B

Or NOTOr NOT

To (measure apo) BTo (measure apo) B

Financial ConstraintsFinancial Constraints

LFT – ALTLFT – ALT RFT – CreatinineRFT – Creatinine TFT – TSHTFT – TSH Lipids (ASCVD) - ?Lipids (ASCVD) - ?

Heart Disease & StrokeHeart Disease & Stroke

Atherosclerosis

Artery Wall Lipid Metabolism Risk Factors Genetics

Pathology LDL/VLDL Hypertension Population

Cytokines HDL Coagulation Epidemiology

Oxidation Bile Diabetes Genetic Markers

Hemodynamics Cholesterol Obesity Candidate Genes

Virus Triglycerides Immune Factors Animal Models

Lp(a) Homocystinuria Environment

A.J. Lusis, J.I. Rotter, R.S. Sparkes Karger, 1992, ISBN 3-8055-5558-XMonography in Human Genetics: Vol. 14, Molecular Genetics of Coronary Artery Disease.

Heart Attack!Heart Attack!

The commonest form of heart disease, CHD killed 3719 people in 2003 and

accounted for 10.2% of the registered deaths…

Source: Mortality statistics, 2003 (provisional data). Department of Health, Census and Statistics Department. The Government of Hong Kong Special Administrative Region.

DyslipoproteinaemiaDyslipoproteinaemia

Assessment of lipidrelated ASCVD risk in practice originally focused

on total cholesterol. In fact, it is thelipoprotein and apolipoprotein particles that exert

the beneficial or adverse effects.Measurement of the cholesterol carried within the

particles particularly LDL and HDLserves as the commonly used default estimate of

their concentrations

Courtesy of National Library of Medicine

The LipoproteinsThe Lipoproteins

VLDLVLDL == Very-low-density lipoproteinVery-low-density lipoproteinIDLIDL == Intermediate-density lipoproteinIntermediate-density lipoproteinLDLLDL == Low-density lipoproteinLow-density lipoproteinHDLHDL == High-density lipoproteinHigh-density lipoprotein

DensityDensity Particle DiameterParticle Diameter Flotation RateFlotation Rate ElectrophoretiElectrophoreticcLipoproteinLipoprotein (kg/L)(kg/L) (nm)(nm) (Sf)(Sf) MobilityMobility

ChylomicronsChylomicrons < 0.95< 0.95 80 - 120080 - 1200 > 400> 400 OriginOrigin

VLDLVLDL 0.95 – 1.0060.95 – 1.006 30 – 8030 – 80 60 – 40060 – 400 Pre-betaPre-beta

IDLIDL 1.006 – 1.0191.006 – 1.019 23 – 3523 – 35 20 – 6020 – 60 Broad betaBroad beta

LDLLDL 1.019 – 1.0631.019 – 1.063 18 – 2518 – 25 0 – 200 – 20 BetaBeta

HDLHDL 1.063 – 1.211.063 – 1.21 5 – 125 – 12 0 – 90 – 9 AlphaAlpha

Chylomicrons

LDL

VLDL

HDL

Free Fatty Acids

The ApolipoproteinsThe Apolipoproteins

HDLHDL == High-density lipoproteinHigh-density lipoprotein LCATLCAT == Lecithin:cholesterol acyltransferaseLecithin:cholesterol acyltransferaseLPLLPL == Lipoprotein lipaseLipoprotein lipase HTGLHTGL == Hepatic triglyceride lipaseHepatic triglyceride lipaseVLDLVLDL == Very-low-density lipoproteinVery-low-density lipoprotein LDLLDL == Low-density lipoproteinLow-density lipoproteinIDLIDL == Intermediate-density lipoproteinIntermediate-density lipoprotein LRPLRP == LDL receptor-related proteinLDL receptor-related protein

Association withAssociation withApolipoprotein Apolipoprotein Main Functions Main Functions CHD RiskCHD Risk

Apo A-IApo A-I Structural for HDL. Ligand for HDL binding. LCAT cofactor.Structural for HDL. Ligand for HDL binding. LCAT cofactor. YesYes

Apo A-IIApo A-II Structural for HDL. Ligand for HDL binding. LCAT cofactor.Structural for HDL. Ligand for HDL binding. LCAT cofactor. NoNo

Modulator of LPL and HTGL activity (?)Modulator of LPL and HTGL activity (?)

Apo A-IVApo A-IV Ligand for HDL binding. LCAT activator.Ligand for HDL binding. LCAT activator. NoNo

Apo A-VApo A-V Intracellular VLDL assembly. Down regulation of LPL (?)Intracellular VLDL assembly. Down regulation of LPL (?) ??

Apo (a)Apo (a) Structural for Lp(a). Structural analogy with plasminogen.Structural for Lp(a). Structural analogy with plasminogen. YesYes

Apo B-48Apo B-48 Structural for chylomicrons.Structural for chylomicrons. NoNo

Apo B-100Apo B-100 Structural for VLDL, IDL and LDL. LDL receptor ligand.Structural for VLDL, IDL and LDL. LDL receptor ligand. YesYes

Apo C-IApo C-I LCAT and LPL activator.LCAT and LPL activator. NoNo

Apo C-IIApo C-II LCAT and LPL activator.LCAT and LPL activator. NoNo

Apo C-IIIApo C-III LPL inhibitor. Modulator of uptake of triglyceride-richLPL inhibitor. Modulator of uptake of triglyceride-rich NoNo

lipoproteins by LRP.lipoproteins by LRP.

Apo DApo D Unknown.Unknown. NoNo

Apo EApo E Ligand for B/E receptors, LRP and apo E2 receptor.Ligand for B/E receptors, LRP and apo E2 receptor. Phenotype, yesPhenotype, yes

Apo FApo F Unknown.Unknown. NoNo

Apo HApo H Unknown.Unknown. NoNo

Apo JApo J Membrane protection(?)Membrane protection(?) NoNo

Apo MApo M Structural for HDL. Transfer of cholesterol.Structural for HDL. Transfer of cholesterol. ??

Apolipoproteins Phospholipid Cholesterol

Triglycerides Cholesterol Esters

Lipoprotein Structure

Apo B-containing Lipoproteins

Segrest et al. Structure of apoB and LDL. J Lipid Res 2001 42:1346–1367.

Apo B, which has a Mr of 550 kD, is the major protein found in LDL and is responsible for the cellular uptake of LDL particles from the plasma (Goldstein & Brown 1982).

Apo B-containing Apo B-containing LipoproteinsLipoproteins

LDLLDL Triglyceride-rich lipoproteinsTriglyceride-rich lipoproteins

VLDLVLDL IDLIDL

Lp(a)Lp(a)

N C E P

G U I D E L I N E S

LIPID

HYPOTHESIS

ANIMAL DATADATA

DEC

REA

SED

OVE

RA

LL

MO

RTA

LITY

1 O

PREVENTION

STUDIES

2O

PREV

ENTI

ON

STUD

IES

REGRESSION

STUDIES

The Full Report of NCEPThe Full Report of NCEP ATP-III ATP-III

http://www.nhlbi.nih.govhttp://www.nhlbi.nih.gov

Executive Summary of The Third Report of The Executive Summary of The Third Report of The National Cholesterol Education Program (NCEP) National Cholesterol Education Program (NCEP)

Expert Panel on Detection, Evaluation, And Expert Panel on Detection, Evaluation, And Treatment of High Blood Cholesterol In Adults Treatment of High Blood Cholesterol In Adults

(Adult Treatment Panel III)(Adult Treatment Panel III)JAMA May 16 2001, 285(19) p2486-97JAMA May 16 2001, 285(19) p2486-97

Should the goal of lipid Should the goal of lipid therapy be based on LDL-C, therapy be based on LDL-C, apo B-100 or non-HDL-C?apo B-100 or non-HDL-C?

Sueta et al. Am J Cardiol 1999; 83: 1303-1307

Source: http://www.lipidsonline.org/

LDL-C as primary target of therapy

Limitations of LDL-C in general LDL particles can be heterogeneous in size, the LDL particle number may be a better indicator of t

he atherogenic potential of the LDL fraction than is LDL–C concentration.

Limitations of LDL –C in patients with hypertriglyceridaemia

Friedewald FormulaFriedewald Formula(Calculated LDL-C)(Calculated LDL-C)

LDL-C = TC –(TG/2.2 + HDL-C)LDL-C = TC –(TG/2.2 + HDL-C)

Estimated value of VLDL-C from TG

BUT does not apply to

chylomicrons (non-fasting)

Friedewald FormulaFriedewald Formula(Calculated LDL-C)(Calculated LDL-C)

Based on two assumptionsBased on two assumptionsFastingFastingTriglyceride <4.5 mmol/LTriglyceride <4.5 mmol/L

IMPORTANT

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0

Triglycerides level (mmol/L)

diffe

renc

e of

LDL

betw

een

calc

ulat

ion

and

mea

sure

men

t(m

mol

/L)

Chylomicrons LDL VLDL

HDL

TC = 31.5

TG = 4.3

HDL-C = 0.52

LDL-C = 29.0 (by calculation)

LDL-C = 5.0 (by direct method)

Apo A1 = <0.25

Apo B = 2.77

99CA074094

Cholestasis & Jaundice

Lp-X?

Free fatty acids

In many cases of fasting In many cases of fasting hypertriglyceridaemia common in hypertriglyceridaemia common in

diabetesdiabetes The clinician has no reliable estimate (usuThe clinician has no reliable estimate (usu

ally an ally an underestimateunderestimate) of the LDL choleste) of the LDL cholesterol by calculationrol by calculation

No objective index of lipid-associated CHD No objective index of lipid-associated CHD risk unless the LDL cholesterol is available risk unless the LDL cholesterol is available (by labour intensive ultracentrifugation)(by labour intensive ultracentrifugation)

Significant bias (usually an Significant bias (usually an overestimateoverestimate) i) in the direct methodn the direct method

Chylomicrons

LDL

VLDL

HDL

Free Fatty Acids

TC = 5.9

TG = 14.3

LDL-C = 2.2 (by direct method)

HDL-C = 0.71

Apo A1 = 0.93 HbA1 = 11.2

Apo B = 1.10 Glucose = 14.2

01C9214160

Poor glycaemic control

To (measure apo) BTo (measure apo) B

Or NOTOr NOT

To (measure apo) B?To (measure apo) B?

All that remains is for its All that remains is for its reliabilityreliability as a predictor as a predictor of CHD risk that may be of CHD risk that may be

superior to LDL-C?superior to LDL-C?

Relative riskRelative risk Much emphasis was placed on estimates of reMuch emphasis was placed on estimates of re

lative risk for CHD accompanying different lipolative risk for CHD accompanying different lipoprotein fractionsprotein fractions

Lipidologists have championed one fraction or Lipidologists have championed one fraction or another as the best predictor of CHDanother as the best predictor of CHD LDL cholesterolLDL cholesterol HDL cholesterolHDL cholesterol Total cholesterol/HDL cholesterolTotal cholesterol/HDL cholesterol Small LDL particlesSmall LDL particles Remnant lipoproteinsRemnant lipoproteins Total apolipoprotein BTotal apolipoprotein B Lipoprotein(a)Lipoprotein(a) Non-HDL cholesterolNon-HDL cholesterol

Predictive Power of Predictive Power of LipoproteinsLipoproteins

Total Cholesterol: Strong independent Total Cholesterol: Strong independent relationrelation

LDL Cholesterol: widely accepted as LDL Cholesterol: widely accepted as independent risk factorindependent risk factor

Reduced levels of HDL cholesterol: Reduced levels of HDL cholesterol: independently predict CHD incidenceindependently predict CHD incidence

High triglyceride levels carry independent High triglyceride levels carry independent predictive power has been less robustpredictive power has been less robust

Total apo BTotal apo B

Signifies atherogenic potential and a Signifies atherogenic potential and a strong predictor of CHD riskstrong predictor of CHD risk

Sniderman AD. Counterpoint: To (measure apo) B or not to (measure apo) B: a critique of modern medical decision-making. Clin Chem 1997; 43: 1310-1314

Apo B as a better treatment index than LDL-C

?In general, statins produce closely similar percent

reductions in concentrations of LDL-C andapo B, and therefore the reasons whyapo B is a better index than LDL-C to

assess adequacy of statin therapy may not be immediatelyobvious. However, in patients with small dense LDL, by

definition, LDL particle number will be higher than LDL-C. Thus, on-treatment LDL-C

concentration will give an inaccurate impression of theextent to which atherogenic particle number has been

reduced, and treatment guided by this value could result inundertreatment.

Sniderman et al. Apolipoproteins versus lipids as indices of coronary risk and as targets for statin treatment. Lancet 2003; 361: 777–80

Practical IssuePractical Issue

What if the laboratory does not What if the laboratory does not measure apo B?measure apo B?

Current MethodologiesCurrent Methodologies

Rate immunonephlometric assays (INA)Rate immunonephlometric assays (INA) Immunoturbidometric assays (ITA)Immunoturbidometric assays (ITA) Enzyme-linked immunosorbent assays (ELISA)Enzyme-linked immunosorbent assays (ELISA)

International Reference Material SP3-07

Relatively expensive

Non-HDL cholesterol and apolipoprotein B in the dysliNon-HDL cholesterol and apolipoprotein B in the dyslipidemic classification of type 2 diabetic patients - Epipidemic classification of type 2 diabetic patients - Epidemiology/Health Services/Psychosocial Research - hdemiology/Health Services/Psychosocial Research - h

igh density lipoproteinigh density lipoprotein

CONCLUSIONS: Non-HDL cholesterol and apoB CONCLUSIONS: Non-HDL cholesterol and apoB are equivalent risk markers in hypertriglyceridemiare equivalent risk markers in hypertriglyceridemic patients, but apoB identifies additional patients c patients, but apoB identifies additional patients with high-risk dyslipidemic phenotypes in normotwith high-risk dyslipidemic phenotypes in normot

riglyceridemic type 2 diabetic patients…riglyceridemic type 2 diabetic patients…

Wagner et al. Diabetes Care 2003; 26: 2048-51.

To (measure apo) BTo (measure apo) B

Or NOTOr NOT

To (measure apo) B?To (measure apo) B?

Apo B vs Non-HDL cholesterolApo B vs Non-HDL cholesterol

Apo B vs Non-HDL Apo B vs Non-HDL cholesterolcholesterol

Because there is one apo B molecule per Because there is one apo B molecule per lipoprotein particlelipoprotein particle

Total apo B concentrations are a measure of Total apo B concentrations are a measure of total particle number of the “atherogenic” total particle number of the “atherogenic” lipoproteinslipoproteins

HDL is a “good” cholesterol. Non-HDL HDL is a “good” cholesterol. Non-HDL cholesterol provides the cholesterol content of cholesterol provides the cholesterol content of all the atherogenic lipoproteinsall the atherogenic lipoproteins

Total apo B was acknowledged (NCEP ATP III) Total apo B was acknowledged (NCEP ATP III) as an alternative to non-HDL cholesterol but as an alternative to non-HDL cholesterol but non-HDL cholesterol was highlighted because of non-HDL cholesterol was highlighted because of wide availability and reliability of estimationwide availability and reliability of estimation

Non-HDL Cholesterol: A Logical Extension Non-HDL Cholesterol: A Logical Extension of the Priority Given to LDL Cholesterol?of the Priority Given to LDL Cholesterol?

Pang et al. Plasma lipid, lipoprotein and apolipoprotein levels in a random population sample of 2875 Hong Kong Chinese adults and their implications (NCEP ATP-III, 2001 guidelines) on cardiovascular risk assessment. Atherosclerosis 2005 (in press).

Overall 39% Men

29% Women

Non-HDL Cholesterol into the Non-HDL Cholesterol into the SpotlightSpotlight

Just a simple calculationJust a simple calculation Easily available with every lipid profileEasily available with every lipid profile Eliminating any additional costsEliminating any additional costs Circumvents the measurement of triglyceriCircumvents the measurement of triglyceri

desdes Patient does not require in the fasting statPatient does not require in the fasting stat

e e (?(?!!)) Avoids the potential inaccuracy of calculatAvoids the potential inaccuracy of calculat

ed LDL cholesteroled LDL cholesterol

Medline SearchMedline SearchYearYear Non-HDLNon-HDL TitleTitle

19971997 88 00

19981998 88 22

19991999 66 11

20002000 1010 11

2001 2001 NCEP ATP-IIINCEP ATP-III 1414 33

20022002 1818 55

20032003 2929 1212

20042004

2005 2005 (~October(~October))

3939

3030

1515

1111

The advantages of using The advantages of using Non-HDL cholesterol in Non-HDL cholesterol in

the diagnosis and the diagnosis and treatment of treatment of

dyslipidaemia?dyslipidaemia?

??Type 2 Diabetes????Type 2 Diabetes??(Metabolic Syndrome)(Metabolic Syndrome)

Jiang et al. Non-HDL cholesterol and apolipoprotein B predict cardiovascular disease events among men with type 2 diabetes.Diabetes Care. 2004 Aug;27(8):1991-7.

Non-high-density lipoprotein Non-high-density lipoprotein cholesterol: why lower is better?cholesterol: why lower is better?

Recent comparative trials of 3-hydroxy-3-methylglutaryl coenzyme A Recent comparative trials of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) suggest that lower is better and that redreductase inhibitors (statins) suggest that lower is better and that reducing low-density lipoprotein cholesterol (LDL-C) levels to below 100 ucing low-density lipoprotein cholesterol (LDL-C) levels to below 100 mg/dL can provide additional clinical benefit. Non-high-density lipoprmg/dL can provide additional clinical benefit. Non-high-density lipoprotein cholesterol (non-HDL-C) contains more atherogenic cholesterol otein cholesterol (non-HDL-C) contains more atherogenic cholesterol than LDL-C and is considered a more accurate measurement of the than LDL-C and is considered a more accurate measurement of the total amount of atherogenic particles in the circulation. Therefore, the total amount of atherogenic particles in the circulation. Therefore, the principle that "lower is better" may also apply to lowering levels of noprinciple that "lower is better" may also apply to lowering levels of non-HDL-C. In persons with high triglycerides (200-499 mg/dL), LDL-C n-HDL-C. In persons with high triglycerides (200-499 mg/dL), LDL-C remains the primary target of therapy, but non-HDL-C is an important remains the primary target of therapy, but non-HDL-C is an important secondary therapeutic target. Non-HDL-C is strongly correlated with secondary therapeutic target. Non-HDL-C is strongly correlated with small dense LDL as well as apolipoprotein B, an established predictosmall dense LDL as well as apolipoprotein B, an established predictor of cardiovascular disease risk. Current evidence indicates that statir of cardiovascular disease risk. Current evidence indicates that statins not only rapidly and dramatically reduce LDL-C, but also have a sins not only rapidly and dramatically reduce LDL-C, but also have a similar effect on non-HDL-C, and that the greater the reduction in LDL-milar effect on non-HDL-C, and that the greater the reduction in LDL-

C, the greater will be the reduction in non-HDL-C.C, the greater will be the reduction in non-HDL-C.

Garg R; Vasamreddy CR; Blumenthal RS. Prev Cardiol 2005 8(3):173-7.

ArgumentsArguments (in favour) (in favour) Both non-HDL cholesterol and apo B are markerBoth non-HDL cholesterol and apo B are marker

s for all of the potentially atherogenic lipoproteins for all of the potentially atherogenic lipoproteins ie, LDL, IDL, Lp(a) and atherogenic VLDL (incls ie, LDL, IDL, Lp(a) and atherogenic VLDL (including remnant-like particles)uding remnant-like particles)

Among these, LDL, IDL and Lp(a) are widely accAmong these, LDL, IDL and Lp(a) are widely accepted as being atherogenicepted as being atherogenic

Evidence is growing that most of the apo B-contEvidence is growing that most of the apo B-containing lipoproteins in VLDL contribute to atherosaining lipoproteins in VLDL contribute to atherosclerosisclerosis

Use of non-HDL cholesterol adds an element of Use of non-HDL cholesterol adds an element of simplicity to guidelines by combining all atherogsimplicity to guidelines by combining all atherogenic lipoproteins into a single “fraction”enic lipoproteins into a single “fraction”

JAMA, July 20, 2005 Vol 294, No. 3 (Reprinted) ©2005 American Medical Association. All rights reserved.

Non–HDL Cholesterol, Apolipoproteins A-Iand B100, Standard Lipid Measures,Lipid Ratios, and CRP as Risk Factorsfor Cardiovascular Disease in Women

ArgumentsArguments (Not in favour) (Not in favour) Earlier ATP reports, making use of both Earlier ATP reports, making use of both

epidemiological data and clinical trial results, epidemiological data and clinical trial results, designated LDL cholesterol as the primary targetdesignated LDL cholesterol as the primary target

This designation has been widely accepted by This designation has been widely accepted by medical communitymedical community

Such that LDL is recognized by most physicians Such that LDL is recognized by most physicians as first target of treatmentas first target of treatment

Modification(s) without stronger evidence would Modification(s) without stronger evidence would introduce considerable “confusion” into the introduce considerable “confusion” into the general practice i.e., the pharmaceutical general practice i.e., the pharmaceutical company company “Market”“Market” interventions interventions

Take Home MessageTake Home Message

The LDL-C test is still The LDL-C test is still valuable, But the Apo B test valuable, But the Apo B test adds valuable information. adds valuable information.

One should also bear in One should also bear in mind that…mind that…

The use of apo B or non-HDL cholesterol will not The use of apo B or non-HDL cholesterol will not completely eliminate the need for a fasting triglycompletely eliminate the need for a fasting triglyceride levelceride level

When an elevated apo B-containing lipoproteins When an elevated apo B-containing lipoproteins or non-HDL cholesterol warrants drug treatment, or non-HDL cholesterol warrants drug treatment, the clinician must determine whether to use as fithe clinician must determine whether to use as first-line therapy an agent that targets LDL cholesrst-line therapy an agent that targets LDL cholesterol (e.g., Statins) or one that targets VLDL cholterol (e.g., Statins) or one that targets VLDL cholesterol (e.g., Fibrates)esterol (e.g., Fibrates)

In such cases, a measure of fasting triglycerides In such cases, a measure of fasting triglycerides and calculation (or a direct measurement) of LDand calculation (or a direct measurement) of LDL cholesterol will still be neededL cholesterol will still be needed

Allan D. Sniderman. Applying apoB to the diagnosis and therapy of the atherogenic dyslipoprot

einemias: a clinical diagnostic algorithm. Curr Opin Lipidol 15:433–438; 2004.

I’m good

ProgressionProgression

RegressioRegressionn

?

?

??

?

?HDL

LDL

VLDL

IDL

RLP

Lp(a)

If treatable, we’re not that bad!

To (measure apo) BTo (measure apo) B

Or NOTOr NOT

To (measure apo) B?To (measure apo) B?

Thank you for your attention