Phospholipid transfer protein-deficient mice absorb less cholesterol

Area of Science:

• Lipid metabolism
• Atherosclerosis research
• Gastrointestinal physiology

Background:

• Phospholipid transfer protein (PLTP) is crucial for lipoprotein metabolism and has implications in atherosclerosis.
• PLTP gene knockout (KO) mice exhibit reduced plasma cholesterol levels.
• The small intestine is a significant site of PLTP expression, suggesting a role in cholesterol absorption.

Purpose of the Study:

• To investigate the role of PLTP in intestinal cholesterol absorption and secretion.
• To determine if PLTP deficiency in the small intestine contributes to lower plasma cholesterol levels.

Main Methods:

• Utilized a dual-labeled cholesterol/sitostanol feeding approach in PLTP KO and wild-type (WT) mice.
• Isolated primary enterocytes from PLTP KO mice for cholesterol uptake studies.
• Quantified cholesterol transport to plasma and liver, and secretion via chylomicrons and intestinal HDL.
• Assessed mRNA levels of Niemann-Pick C1-like 1 (NPC1L1) and ATP-binding cassette transporter A1 (ABCA1), and microsomal triglyceride transfer protein (MTP) activity.

Main Results:

• PLTP KO mice demonstrated significantly reduced cholesterol absorption compared to WT mice.
• Primary enterocytes from PLTP KO mice showed decreased cholesterol uptake.
• NPC1L1 mRNA levels were significantly lower in the small intestine of PLTP KO mice.
• Cholesterol transport to plasma and liver was reduced in PLTP KO mice, with diminished secretion via chylomicrons and intestinal HDL.
• ABCA1 mRNA and MTP activity were significantly decreased in the small intestine of PLTP KO mice.

Conclusions:

• PLTP deficiency impairs both cholesterol uptake and secretion in the small intestine.
• These findings highlight PLTP as a potential therapeutic target for managing plasma cholesterol levels and mitigating atherosclerosis.