CD36 is important for chylomicron formation and secretion and may mediate cholesterol uptake in the proximal intestine.
OBJECTIVE
Studies are aimed to determine the role of CD36 in intestinal lipid absorption.


METHODS
Knock-out (KO) and wild-type (WT) lymph fistula mice were used to study fatty acids (FA) and cholesterol uptake, and chylomicron formation and secretion. Uptake of FA and cholesterol was studied by using sucrose polybehenate and fecal dual isotope methods, respectively.


RESULTS
The CD36 KO exhibited significant accumulation of dietary cholesterol in the intestinal lumen at the end of 6-hour lipid infusion and significant reduction of dietary cholesterol transport into the lymph. Fecal dual isotope studies, however, did not show any significant difference in cholesterol uptake, suggesting that given sufficient time, the KO intestine could compensate for the reduced cholesterol uptake observed in the acute lymph fistula studies. Recovery of dietary FA in the intestinal lumen was comparable between WT and KO, consistent with the sucrose polybehenate study. However, the KO mice accumulated more, albeit not significantly, dietary triacylglycerols in the intestine, followed by a significant reduction in lymphatic transport. The ratio of intestinal dietary triacylglycerols to FA was not higher in WT than KO, arguing against impaired lipid esterification. It is rather a deficiency in the formation and secretion of chylomicrons, as supported by the significantly less apolipoprotein B-48 and the smaller, albeit not significantly, lipoprotein particles secreted into the lymph of the KO.


CONCLUSIONS
CD36 may play an important role in chylomicron formation and secretion and may also facilitate cholesterol uptake in the proximal intestine.
Nauli
Andromeda M
AM
Department of Pathology and Laboratory Medicine, Genome Research Institute, University of Cincinnati College of Medicine, 2120 Galbraith Road, Cincinnati, OH 45237, USA.
Nassir
Fatiha
F
Zheng
Shuqin
S
Yang
Qing
Q
Lo
Chun-Min
CM
Vonlehmden
Sarah B
SB
Lee
Dana
D
Jandacek
Ronald J
RJ
Abumrad
Nada A
NA
Tso
Patrick
P
D000818:Animals; D001053:Apolipoproteins / Q000378:metabolism; D018955:CD36 Antigens / Q000235:genetics / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002784:Cholesterol / Q000493:pharmacokinetics*; D002855:Chromatography, Thin Layer; D002914:Chylomicrons / Q000378:metabolism*; D004041:Dietary Fats / Q000493:pharmacokinetics; D004386:Duodenum / Q000378:metabolism*; D008074:Lipoproteins / Q000737:chemistry / Q000378:metabolism; D008208:Lymphatic System / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D010316:Particle Size; D013395:Sucrose / Q000494:pharmacology; D014304:Triolein / Q000493:pharmacokinetics; D014316:Tritium
D001053:Apolipoproteins; D018955:CD36 Antigens; D002250:Carbon Radioisotopes; D002914:Chylomicrons; D004041:Dietary Fats; D008074:Lipoproteins; D014316:Tritium; D014304:Triolein; D013395:Sucrose; D002784:Cholesterol