Imbalance in superoxide dismutase/thioredoxin reductase activities in hypercholesterolemic subjects: relationship with low density lipoprotein oxidation

Serum lipids, highly sensitive C-reactive protein (hs-CRP), lipid and protein oxidation, oxidized LDL (LDLox) and LDLox autoantibodies (LDLoxAB) levels and enzymes activities were measured in a total of 116 subjects that were divided into the following groups according to their LDL levels: low-LDL group (LDL？<？100？mg/dL, n？=？23), intermediate-LDL group (LDL 100–160？mg/dL, n？=？50) and high-LDL group (LDL？>？160？mg/dL, n？=？43).The LDLox and hs-CRP levels increased in the high-LDL group (2.7- and 3.7- fold, respectively), whereas the intermediate and high-LDL groups had higher LDLoxAB (2.2- and 3.1-fold) when compared to low-LDL group (p？<？0.05). Similarly, SOD activity, the atherogenic index (AI) and protein oxidation were also higher in the intermediate (1.3-, 1.3- and 1.2-fold) and high-LDL (1.6-, 2.3- and 1.6-fold) groups when compared to the low-LDL group (p？<？0.05). Lipid oxidation and SOD/TrxR-1 ratio increased only in the high-LDL group (1.3- and 1.6-fold) when compared to the low-LDL group (p？<？0.05). The SOD/TrxR-1 ratio was positively correlated to TBARS (r？=？0.23, p？<？0.05), LDLox (r？=？0.18, p？<？0.05), LDLoxAB (r？=？0.21, p？<？0.05), LDL (r？=？0.19, p？<？0.05) and AI (r？=？0.22, p？<？0.05). PON1 and TrxR-1 activities were similar among groups.Some oxidative events initiate when LDL levels are clinically acceptable. Moreover, hypercholesterolemic patients have an imbalance in SOD and TrxR-1 activities that is positively associated to LDL oxidation.