Article

Postprandial triglyceride-rich lipoprotein metabolism and insulin sensitivity in nonalcoholic steatohepatitis patients

Lipids (impact factor: 2.13). 04/2012; 36(10):1117-1124. DOI:10.1007/s11745-001-0822-5 pp.1117-1124

ABSTRACT Nonalcoholic steatohepatitis (NASH) is a syndrome frequently associated with obesity, diabetes mellitus, and dyslipidemia.
Increased fasting insulinemia and blood glucose levels may trigger a reduced catabolism of lipoproteins rich in triglycerides
by lipoprotein lipase (LPL) and an increase in their fasting and postprandial levels. An association between postprandial
lipemia and coronary heart disease has been observed, and many studies now support this concept. The most important result
of our study is the increase in triglyceride-rich lipoproteins response after a fat load in NASH patients, the increase of
incremental area under the postprandial curve, and the duration of the hypertriglyceridemic peaks. The persisting postprandial
plasma triglyceride elevation in NASH patients was mostly due to the elevated plasma level of large triglyceride-rich particles.
These data are coupled with lower plasma HDL2-cholesterol levels. As for lipoprotein analyses, the number of apolipoprotein
B100 (ApoB100) particles is not significantly different between the two groups, and the higher content of triglycerides in
NASH very low density lipoproteins (VLDL) increases the triglyceride-to-ApoB ratio and the particle size. A decreased enzymatic
activity of LPL or a defective assembly and secretion of VLDL from hepatocytes due to a moderate reduction in microsomal triglyceride
transfer protein could be involved in the overloading of VLDL. Moreover, the undetectable levels of ApoB48 in triglyceride-rich
lipoproteins fraction A could be related to the synthesis of smaller and denser chylomicrons. NASH patients not only are insulin
resistant but also tend to present alterations in fatty meal delivery, suggesting that an increase in fasting plasma insulin
and glucose, with insulin resistance, joins with depressed metabolism of triglyceride-rich lipoproteins. An increase in postprandial
triglyceride levels with production of large VLDL suggests an atherogenic behavior of lipid metabolism, in accordance with
the high prevalence of the metabolic syndrome in NASH patients. This paper suggests that a fat load may be useful in early
detection of atherogenic risk in the presence of otherwise normal fasting plasma lipids.

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Keywords

atherogenic risk
 
defective assembly
 
denser chylomicrons
 
depressed metabolism
 
elevated plasma level
 
fasting plasma insulin
 
fat load
 
hypertriglyceridemic peaks
 
Increased fasting insulinemia
 
large VLDL
 
lipid metabolism
 
lipoprotein analyses
 
lipoprotein lipase
 
NASH patients
 
normal fasting plasma lipids
 
postprandial curve
 
reduced catabolism
 
triglyceride-rich lipoproteins
 
triglyceride-rich lipoproteins response
 
two groups