Clinical trial NCT01603758: Physiological Study of Human Cholesterol Metabolism and Excretion
Official title: Reverse Cholesterol Transport in Humans
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: PHASE1
Conditions: Coronary Heart Disease
Cardiovascular Disease
Dyslipidemia
Disorder of Cholesterol Metabolism
Keywords: Cholesterol
Spectrometry, mass
Deuterium
Kinetics
Cholesterol absorption
Coronary Heart Disease
Lead sponsor: Washington University School of Medicine
Sponsor class: OTHER
Collaborators: name: National Heart, Lung, and Blood Institute (NHLBI)
First posted: 2012-05-23
Enrollment: 132
Sex: ALL
Minimum age (years): 18
Maximum age (years): 80
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: BASIC_SCIENCE

Brief summary: The underlying hypothesis is that whole body cholesterol - including cholesterol present in tissues that cannot be measured by standard blood tests - is related to heart disease risk. Endogenous cholesterol will be labeled with an intravenous infusion of one type of cholesterol tracer and dietary cholesterol will be labeled with another. These tracers will be used to measure how fast cholesterol is synthesized and excreted using mass spectrometry to distinguish the tracers. Data will be related to circulating biomarkers (blood tests) and to the thickness of the lining of the carotid artery. The effect of the drug ezetimibe on these processes will also be determined. Successful completion of this study will give us more knowledge about cholesterol metabolism that may be useful in designing new drugs and treatments for patients with heart disease, especially those that are already receiving maximum amounts of current medications.

Detailed description: The central hypothesis of this proposal is that reverse cholesterol transport is related to coronary heart disease (CHD) risk. It is complementary to the concept that reduction of cholesterol biosynthesis with statin drugs prevents CHD, but it focuses on whole body cholesterol metabolism and kinetic cholesterol transport rather than on static levels of circulating lipoproteins. Although this is an old idea, it has not been adequately tested in humans because of lack of suitable methods. In this proposal we will apply innovative stable isotope and mass spectroscopic technology to study reverse cholesterol transport in human subjects. The first specific aim is to improve the preparation of intravenous deuterated cholesterol tracer, a critical limiting element in the study of whole body cholesterol metabolism. The second aim is to use that intravenous tracer, along with a different oral tracer, to partition fecal cholesterol into excreted endogenous cholesterol, unabsorbed dietary cholesterol and newly-synthesized cholesterol derived from the liver and intestine. Measurements will be made during consumption of a controlled diet provided by the metabolic kitchen. The pool size of the rapidly-mixing body cholesterol pool will be measured along with the fractional rate of cholesterol catabolism. These direct measures of reverse cholesterol transport will be correlated with plasma biomarkers and with metabolic covariates. The relation of reverse cholesterol transport to carotid intima-media thickness will be determined. The third specific aim will use similar methods to study the mechanism of action for the widely-used drug ezetimibe. The fractional rate of endogenous cholesterol excretion and the rate of plasma cholesterol turnover will be determined in two periods, one with drug and one with placebo treatment. This work represents a new direction for cholesterol research with the potential to develop new and complementary methods of reducing CHD risk that can be added to diet and statin drug treatment.

Eligibility criteria: Inclusion Criteria:

* Aim II. 100 subjects aged 30-80 with stable medical and/or surgical illnesses.
* Aim III. 30 subjects age 18-80 with LDL cholesterol \<190, fasting triglycerides\<250 and stable medical or surgical illnesses.

Exclusion Criteria:

* Aim II. Subjects taking ezetimibe, bile acid sequestrants or with gastrointestinal or liver disease will be excluded since these may affect whole body cholesterol metabolism.
* Subjects with coronary heart disease or other medical illnesses will not be excluded if medically stable.
* Adults under age 30 and children will be excluded because in our current database there is no relation between carotid intima-media thickness and cardiovascular risk factors in this younger group.
* Aim III. Individuals have risk factors for coronary heart disease that mandate drug treatment according to the National Cholesterol Education Program guidelines will be excluded.

Primary outcomes:
measure: Fractional Excretion of Endogenous Cholesterol
timeFrame: 4 years
Secondary outcomes:
Other outcomes:
Locations:
city: St. Louis
country: United States
facility: Washington University School of Medicine
state: Missouri
Study officials:
affiliation: Washington University School of Medicine
name: Richard E Ostlund, MD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Lin X, Racette SB, Ma L, Wallendorf M, Davila-Roman VG, Ostlund RE Jr. Endogenous Cholesterol Excretion Is Negatively Associated With Carotid Intima-Media Thickness in Humans. Arterioscler Thromb Vasc Biol. 2017 Dec;37(12):2364-2369. doi: 10.1161/ATVBAHA.117.310081. Epub 2017 Oct 5.
citation: Lin X, Racette SB, Ma L, Wallendorf M, Ostlund RE Jr. Ezetimibe Increases Endogenous Cholesterol Excretion in Humans. Arterioscler Thromb Vasc Biol. 2017 May;37(5):990-996. doi: 10.1161/ATVBAHA.117.309119. Epub 2017 Mar 9.