Relations of lysophosphatidylcholine in low-density lipoprotein with serum lipoprotein-associated phospholipase A2, paraoxonase and homocysteine thiolactonase activities in patients with type 2 diabetes mellitus

AimsWe studied the relations of lysophosphatidylcholine (lyso-PC) in LDL with serum lipoprotein-associated phospholipase A2 (Lp-PLA2), paraoxonase and homocysteine thiolactonase (HTLase) activities in patients with type 2 diabetes mellitus.MethodsLyso-PC was measured by electrospray ionization-liquid chromatography/mass spectrometry. Paraoxonase and HTLase activities were measured with paraoxon and γ-thiobutyrolactone as substrates, respectively.ResultsSerum HTLase and paraoxonase activities were significantly suppressed in diabetic patients (n = 96) compared with control (n = 25), whereas serum Lp-PLA2 did not differ in control and diabetic patients. Lyso-PC contents in LDL correlated with serum Lp-PLA2 activity positively and with serum HTLase activity negatively. Stepwise regression analysis revealed that serum Lp-PLA2 and HTLase activities independently contributed to lyso-PC contents in LDL. In patients with diabetic nephropathy, lyso-PC contents in LDL were increased with reduced serum HTLase and paraoxonase activities compared with control, while serum Lp-PLA2 activity did not differ. On the other hand, 3-month treatment with simvastatin reduced both lyso-PC contents in LDL and serum Lp-PLA2 activity in hypercholesterolemic diabetic patients, while serum HTLase or paraoxonase activities did not change.ConclusionsIncreased lyso-PC contents in LDL were associated with the suppressed HTLase activity, and serum Lp-PLA2 and HTLase activities may be related to lyso-PC in type 2 diabetic patients.