LDL apheresis lowers apoE4, HDL cholesterol levels
MedWire News: Low-density lipoprotein (LDL) apheresis reduces plasma levels of apolipoprotein (apo)E4, possibly via a selective reduction in high-density lipoprotein (HDL) cholesterol, US researchers believe.
They say that more work is needed to clarify the impact of LDL apheresis – a treatment used for severe hyperlipidemia – on the cardiovascular and cerebrovascular system.
A team led by Patrick Moriarty (University of Kansas Medical School, Kansas City) tested the hypothesis that LDL apheresis would reduce levels of apoE4. This was based on the knowledge that LDL apheresis acts by attracting positively charged plasma proteins, and that apoE4 is a positively charged.
They studied 10 patients with familial hypercholesterolemia who were undergoing chronic biweekly LDL apheresis and had detectable levels of the apoE4 isoform. Eight of the participants were women and all were taking lipid-lowering therapies.
Analysis of plasma revealed that mean plasma apoE4 levels fell by 39% after a single LDL apheresis session. Other treatment-induced changes included a 38% reduction in triglycerides, a 75% fall in LDL cholesterol, and an 18% drop in HDL cholesterol.
The reduction in HDL cholesterol is surprising, says the team, since HDL has a negative surface membrane charge. Of further interest, the change in HDL cholesterol significantly negatively correlated with baseline apoE4 and significantly positively correlated with the treatment-induced change in apoE4.
Moriarty et al propose a number of mechanisms for the removal of HDL cholesterol during LDL apheresis but admit that the precise pathway is unclear.
“The change to inflammatory HDL and the significant reduction in apoE4 and serum amyloid A after LDL apheresis raises the question of what association exists between inflammatory HDL and these HDL-bound apolipoproteins,” they conclude in the American Journal of Cardiology.
“Additional research is needed to examine the effect on cardiovascular and cerebrovascular system from the reduction of apoE4 and HDL cholesterol by LDL apheresis.”
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By Joanna Lyford