Mitochondrial Triglyceride Transfer Protein Inhibition: New Achievements in the Treatment of Dyslipidemias
Michael S. Kostapanos, Evangelos C. Rizos, Nikolaos Papanas, Efstratios Maltezos and Moses S. Elisaf
Affiliation: Department of Internal Medicine, School of Medicine, University of Ioannina, 451 10 Ioannina, Greece.
Keywords: Mitochondrial transfer protein, cholesterol, cardiovascular disease, fatty liver.
Current lipid-lowering drugs are often unable to achieve low density lipoprotein cholesterol (LDL-C) goals. Moreover, despite
LDL-C lowering mostly by statins, a considerable residual vascular risk remains. This is partly associated with atherogenic dyslipidemia
where apolipoprotein (apo) B-containing lipoproteins predominate. Mitochondrial Triglyceride (TG) transfer protein (MTP) is a key enzyme
for apoB-containing lipoprotein assembly and secretion. This is mostly attributed to its capacity to transfer lipid components (TGs,
cholesterol esters and phospholipids) to the endoplasmic reticulum lumen, where these lipoproteins are assembled. Several agents were
developed to inhibit MTP wherever it is expressed, namely the liver and/or the intestine. Liver-specific MTP inhibitors reduce secretion
of very low density lipoproteins (VLDL) mostly containing apoB100, while the intestine-specific ones reduce secretion of chylomicrons
containing apoB48. These drugs can significantly reduce total cholesterol, LDL-C, TGs, VLDL cholesterol, as well as apoB levels in
vivo. They may also exert anti-atherosclerotic and insulin-sensitizing effects. Limited clinical data suggest that these compounds can also
improve the serum lipid profile in patients with homozygous familial hypercholesterolemia (HoFH). The accumulation of unsecreted fat
in the liver and intestinal lumen is associated with elevation of aminotransferases and steatorrhea. Liver steatosis can be avoided by the
use of intestine-specific MTP inhibitors, while steatorrhea by low-fat diet. Future indications for these developing drugs may include
dyslipidemia associated with insulin resistant states, familial combined hyperlipidemia and HoFH. Future clinical trials are warranted to
assess the efficacy and safety of MTP inhibitors in various clinical states.
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