Increased plasma apoM levels impair triglyceride turnover in mice

Area of Science:

• Lipid metabolism
• Biochemistry
• Endocrinology

Background:

• Apolipoprotein M (apoM) transports Sphingosine-1-Phosphate (S1P) in plasma, primarily bound to high-density lipoproteins (HDL).
• ApoM deficiency is linked to increased brown adipose tissue activity and rapid triglyceride turnover.
• The precise role of apoM/S1P in triglyceride metabolism remains unclear.

Purpose of the Study:

• To investigate the impact of the apoM/S1P axis on triglyceride metabolism.
• To explore potential molecular mechanisms underlying apoM's influence on lipid turnover.
• To assess the therapeutic potential of targeting the apoM/S1P axis for hypertriglyceridemia.

Main Methods:

• Utilized a female human apoM transgenic mouse model (apoM-Tg) with elevated plasma apoM and S1P.
• Compared triglyceride turnover and metabolic pathways in apoM-Tg mice versus wild-type (WT) mice.
• Analyzed plasma lipase activity and fibroblast growth factor 21 (FGF21) levels.

Main Results:

• ApoM-Tg mice exhibited reduced plasma triglyceride turnover rates.
• Subcutaneous adipocytes in apoM-Tg mice showed lower free fatty acid uptake.
• Plasma lipase activity and FGF21 levels were decreased in apoM-Tg animals.

Conclusions:

• The apoM/S1P axis plays a significant role in maintaining balanced triglyceride metabolism.
• Targeting the apoM/S1P axis presents a potential therapeutic strategy for hypertriglyceridemia.
• Caution is advised regarding S1P-analogue therapies due to potential dyslipidemia risks.