A lipidomic analysis approach in patients undergoing lipoprotein apheresis

Lipoprotein apheresis such as heparin-induced extracorporal LowDensityLipoprotein (LDL) Cholesterol precipitation (HELP) reduces apolipoprotein B-containing lipoproteins, most importantly low-density-lipoprotein (LDL), and lipoprotein (a) [Lp(a)]. It is used in patients with atherosclerotic disease and therapy-refractory hypercholesterolemia or progressive atherosclerotic disease in patients with elevated Lp(a). While lipid-lowering effects of lipoprotein apheresis are well-established, there are only sparse data regarding the effect of apheresis on individual omega-6 and omega-3 polyunsaturated fatty acids (n-6 PUFA and n-3 PUFA), such as arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which could increase (AA) or decrease (EPA and DHA) cardiovascular risk. Here we analyzed different omega-6 and omega-3 fatty acids in the blood of patients undergoing a single HELP apheresis procedure using gas chromatography (GC). Furthermore, we assessed the effect of HELP treatment on formation of lipid metabolites and mediators arising from these polyunsaturated fatty acids in the plasma by LC/ESI-MS/MS. Lipoprotein apheresis reduced the concentrations of fatty acids analyzed in the plasma by 40-50%. This was similar for AA, EPA and DHA. The reduction in fatty acid plasma levels was similar to the reduction of total triglycerides. However there was a trend towards an increase of PUFA metabolites associated with platelet activation, such as 12-hydroxyeicosatetraenoic acid (12-HETE) and 14-hydroxydocosahexaenoic acid (14-HDHA). These data indicate that HELP apheresis could interfere with achieving higher levels of n-3 PUFA in the plasma. Lipid apheresis treatment might also increase the formation of potentially pro- as well as anti-inflammatory lipid mediators derived from AA or EPA and DHA.