The Susceptibility of low density lipoprotein (LDL) to oxidation and its relation with oxidant-antioxidant balance in psotiatic patients

Psoriasis is a common chronic and recurrent inflammatory skin disease that has been associated with abnormal plasma lipid metabolism, increased oxidative stress, and increased frequency of cardiovascular events. The current study was designed to evaluate the susceptibility of low density lipoprotein (LDL) to oxidation by using lag time, the levels of autontibodies against oxidized LDL (auAb-oxLDL) as an indicator of in vivo LDL oxidation and its associations with oxidant-antioxidant status in psoriasis. The lag time (t-lag) followed in the formation of conjugated dienes during in vitro copper catalyzed-LDL oxidation was determined spectrophotometrically to investigate the susceptibility of LDL to oxidation. The study group included 35 patients with psoriasis (18 females and 17 males) and 35 sex- and age-matched healthy volunteers (16 females and 19 males). The levels of plasma lipids, lipoproteins, lipid peroxidation products, antioxidant enzymes, acute phase reactants and auAb-oxLDL, the kinetics of copper catalyzed-LDL oxidation and antioxidant enzyme activities and lipid peroxide level in erythrocytes were determined. The mean levels of atherogenic lipids (TC, TG and LDL-C), lipid peroxidation indicators [LDL-TBARS, oxLDL-TBARS, erythrocyte TBARS, plasma lipid hydroperoxide (LHP), serum auAb-oxLDL and maximum dien concentration (MDC) in LDL)] and acut phase reactants (CRP, ESR, PMN-leukocytes, ceruloplasmin and fibrinogen) in patients with psoriasis were found significantly higher those of healthy subjects, but antioxidant enzyme activities [catalase (Cat), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activities in erythrocyte and SOD activitiy in117 plasma], t-lag and HDL-C levels were found significantly lower. TG levels were foun to be significantly increased in isolated LDL and HDL. If correlatios are to be explained in general terms, auAb-oxLDL, MDC and oxLDL- TBARS showed positive correlations either with themselves or with atherogenic lipid parameters and lipid peroxidation products but negative correlation with antioxidant enzyme (particularly plasma SOD). On the other hand, negative correlations were observed between t-lag and VLDL- and LDL-TG. There were positive correlations either between serum LDL cholesterol and isolated LDL cholesterol or between serum HDL cholesterol and isolated HDL cholesterol. It was concluded that psoriatic patients must be considered as a group with an increased atheroclerotic risk bacuse of increased oxidant stress, decreased antioxidant capacity and changes in lipid and lipoprotein structure, and so increased the formation autoantibodies Key words : Psoriasis, LDL oxidation, antioxidants, atherosclerosis.