the etiology of psoriasis is unknown , but genetic , metabolic , and 
 immunologic mechanisms have been proposed .
it is known that psoriasis can occur due to abnormalities in essential fatty acid metabolism , lymphokine release , free radical generation , and lipid peroxidation . 

alterations in plasma lipid and lipoprotein composition including 
 a tendency toward an increase in total cholesterol ( tc ) and 
 triglyceride ( tg ) and decrease in high - density lipoprotein 
 cholesterol ( hdl - c ) levels suggest that psoriasis may associate 
 with the disorders of lipid metabolism [ 2 , 3 ] .
healthy skin 
 secretes 85 mg of cholesterol within 24 hours whereas a 
 psoriatic patient loses 12 grams of cholesterol with scales 
 during that time .
the morphology of psoriatic skin is characterized by epidermal 
 thickness and parakeratosis , a pronounced dermal vascular plexus , 
 and the presence inflammatory cells in the superficial dermis and 
 epidermis
. increased polymorph nuclear leukocyte levels damage 
 surrounding tissue by releasing reactive oxygen species produced 
 via nadph oxidase / myeloperoxidase and proteolytic enzymes . 

increased production of oxygen metabolites is a common feature of 
 most human diseases including psoriasis and it usually triggers an 
 upregulation of the antioxidant capacity , which is overwhelmed . 

when the oxidative stress develops , it leads to the oxidative 
 damage of lipids and proteins [ 2 , 4 , 5 ] .
oxidation of the 
 low - density lipoproteins ( ldl ) results in the production of 
 modified ldl .
one of the major and early lipid peroxidation 
 products is oxidized low - density lipoprotein ( ox - ldl ) .
high titers of autoantibodies against ox - ldl have been reported in 
 patients with psoriasis .
the level of autoantibodies against 
 ox - ldl has been suggested to reflect the in vivo oxidation of ldl 
 [ 7 , 8 ] .
the presence of ox - ldl accumulation in psoriatic skin sample has not been shown before .
the current study has been designed to evaluate the presence of ox - ldl accumulation in skin 
 biopsy materials of psoriatic patients .
this prospective study was performed in the psoriatic patients 
 attending the dermatology outpatient clinic of zonguldak karaelmas 
 university hospital .
eighty four psoriatic patients who were 
 diagnosed clinically and histopathologically by the department of 
 dermatology and a total of 40 age - and sex - matched healthy 
 controls recruited from the general population as a control group 
 were enrolled in the study .
the patients with 
 secondary hyperlipidemia such as chronic renal insufficiency , 
 nephrotic syndrome , hypothyroidism , diabetes mellitus , obstructive 
 liver disease , and the connective tissue disease were excluded . 

all patients and controls were included in the study after giving 
 an informed consent .
the height and weight of all subjects were recorded and their body 
 mass indexes were calculated as weight ( kg)/height ( m ) .
blood samples were taken after a 12-hour overnight fast and sera 
 were separated by low - speed centrifugation for 15 min .
the 
 levels of serum tc , hdl - c , ldl cholesterol ( ldl - c ) , and tg were 
 determined by enzymatic methods using a roche cobas integra 800 
 autoanalyzer .
the skin punch biopsy specimens were collected from both lesional 
 and nonlesional skin of 84 psoriatic patients .
the presence 
 of ox - ldl in biopsy materials of psoriatic individuals was 
 evaluated using an immune - fluorescent staining method .
the slides 
 were prepared from biopsy sections , which were cut at 7-micron 
 thickness .
slides were further divided into two pieces ; one was 
 used for the test and the other was used for negative control . 

thirty l anti - oxidized ldl igg solution ( mouse igg2 
 antibodies , antibodyshop , copenhagen , denmark ) as primary antibody 
 was added only on test slides , and the control slides were 
 manipulated only with the same amount of phosphate buffered saline 
 solution ( pbs ) .
after 30 minutes of incubation in a humid chamber 
 at room temperature , both the control and test slides were washed 
 with ( pbs ) , and 30 l fitc ( fluorescent 
 isothiocyanate)-labeled goat anti - mouse igg ( chemicon 
 international , california , usa ) was administered as a 
 conjugate substance . for a further 30 minutes ,
the slides were kept and 
 incubated at room temperature , and then washed with the standard 
 pbs solution .
after open - air drying , slides were examined under 
 fluorescent microscopy at 100x magnification ( leica dmrx , wetzlar , 
 germany ) .
differences in continuous variables between the patient and the 
 control groups were analyzed using the student t - test . 

mann - whitney u test was used to compare nonparametric variables 
 between two groups .
all 
 values were expressed as mean  standard deviation ( sd ) 
 unless otherwise stated .
table 1 illustrates the clinical and demographic 
 characteristics of the study population . there was no 
 statistically significant difference between psoriatic patients 
 and the controls considering age , sex , weight , height , or bmi 
 ( p > .05 ) .
tc , tg , and ldl - c levels were significantly 
 higher , but hdl - c levels were lower in the psoriatic patients than 
 in the control subjects .
hdl - c levels were significantly lower in the 
 female psoriatic patients than in the female control subjects 
 ( p < .05 ) .
there was no statistically difference for tc , tg , and 
 ldl - c levels between the psoriatic and the control subjects in the 
 female group ( table 3 ) .
tc , tg , and ldl - c levels were 
 significantly higher in the male psoriatic patients than in the 
 male control subjects ( p < .05 ) .
there   was no 
 statistically difference in hdl - c levels between the 
 psoriatic and the control subjects in male group 
 ( table 4 ) .
we did not observe any positive immune - fluorescent staining in the 
 nonlesional skin biopsy materials of the psoriatic patients . 

significant positive immune - fluorescent staining was observed in 
 the psoriatic skin biopsy materials . the dense cellular staining 

among the many studies on serum lipid values in psoriasis , 
 conflicting results have been reported . in studies on serum tc 
 levels in psoriatic patients ,
high [ 2 , 9 , 10 ] , low [ 1 , 11 ] , 
 and normal [ 12 , 13 ] values have all been reported . in our 
 study
, we found significantly higher levels of tc values in the 
 psoriatic patients ( p < .05 ) .
as for serum ldl - c levels , high 
  or normal [ 1 , 10 , 12 ] values have also been reported in psoriasis .
we found that ldl - c values in the patients with psoriasis were significantly higher than the control group 
 ( p < .05 ) .
normal [ 9 , 10 , 13 ] and low [ 1 , 2 ] serum levels of hdl - c have been detected . in our study
hdl - c levels in 
 psoriatic patients were significantly lower than the control group 
 ( p < .01 ) .
the same controversy exists regarding serum tg levels , high 
 [ 1 , 2 ] , low , and normal [ 9 , 10 , 12 ] values have also been reported in psoriasis .
we found that tg values in the 
 psoriatic patients were significantly higher than the control 
 group ( p < .001 ) .
the variety of data presented may be due to the fact that the 
 patients included in statistical analyses suffer from different 
 forms of psoriasis such as erythroderma and they undergo various 
 treatments .
tc , tg , and ldl - c levels were significantly higher in the male 
 psoriatic patients than in the male control subjects .
there was no 
 statistically difference in the female groups . only for the 
 females , hdl - c levels were lower in the psoriatic patients than in 
 the control subjects .
considering the results of our research we would 
 suggest analyzing the lipid profiles separately in males and 
 females .
native ldl is only taken up modestly by macrophages , whereas 
 modified ldl is rapidly taken up via scavenger receptors 
 .
the major modification of ldl particles in vivo is believed to be the oxidation of both its lipid and protein 
 components . oxidized or modified
the oxidized ldl hypothesis is discovered by goldstein et al .   and modified by steinberg et al . .
the current oxidative modification or stress hypothesis 
 of atherosclerosis predicts that ldl oxidation is an early , 
 essential event in atherosclerosis and that ox - ldl does contribute 
 to both initiation and progression of atherosclerosis .
the oxidative modification hypothesis focuses on the concept that 
 ldl in its native form is not atherogenic .
the presence of ox - ldl 
 in atherosclerotic lesions has been studied using antibodies that 
 recognize specific epitopes on ox - ldl , which are not present in 
 its native , nonoxidized , form .
these antibodies avidly stain 
 atherosclerotic lesions in humans with no demonstrable staining in 
 normal arteries .
a typical feature of atherosclerosis is the accumulation of 
 oxidatively modified ldls within plaques .
also these lipoproteins 
 are considered to contribute to the inflammatory state of 
 atherosclerosis and to play a key role in its pathogenesis 
 .
the cellular uptake of ox - ldl leads to the generation of reactive oxygen species ( ros ) .
ros are potentially very harmful substances , because they can react with proteins , 
 dna , or lipids . in other words ,
the importance of this manuscript is to show the existence of 
 ox - ldl in psoriatic skin .
this study shows for the first 
 time the accumulation of oxidized low - density lipoprotein in 
 psoriatic skin lesions by direct immune - fluorescent method .
ox - ldl 
 or anti - ox - ldl antibody levels can be measured in blood samples or 
 body fluids by conventional biochemical and immunological methods . 

especially , the level of anti - ox - ldl has been suggested to reflect 
 the in vivo oxidation of ldl .
the studies of vanizor kural   and rem 
 have demonstrate the existence of these antibodies in psoriasis .
the 
 level of anti - ox - ldl antibody was positively correlated with tc 
 and negatively correlated with hdl - c in their studies . in our 
 study , we detected accumulation of ox - ldl in psoriatic skin .
this 
 accumulation is markedly increased especially in upper epidermis . 
 the upper - epidermal cells had dens cellular staining with 
 anti - ox - ldl antibodies .
we did not observe any positive immune - fluorescent staining in the 
 nonlesional skin biopsy materials of the psoriatic patients .
have observed that tissue - cultered skin fibroblasts from 
 psoriatic patients have reduced ldl receptor activity .
their study has no difference in ldl receptor activity between 
 involved and uninvolved skin from our psoriasis patients . in our 
 study , we only focused on the epidermal layer of involved and 
 uninvolved skin from psoriatic patients .
we detected accumulation 
 of ox - ldl in the upper epidermis of the involved skin from the 
 psoriatic patients .
ox - ldl can use native ldl receptor . however , 
 it has a high - affinity advantage than its native form . in conclusion ,
ox - ldl is an important marker of oxidative stress 
 and lipid peroxidation process .
this capability may directly affect psoriatic epidermis and we believe that the accumulation of 
 ox - ldl in the psoriatic skin may have an important role in 
 pathogenesis of psoriasis .
 background . 
 psoriasis is a chronic inflammatory skin disease characterized by an accelerated turnover of epidermal cells and an incomplete differentiation in epidermis with lesion . 
 however , the exact etiology of psoriasis is unknown . 
 abnormalities in essential fatty acid metabolism , free radical generation , lipid peroxidation , and   release of lymphokines have been proposed . objective .   
 our purpose was to evaluate the plasma lipids and oxidized low - density lipoprotein accumulation in psoriatic skin lesion in order to ascertain the possible participation of oxidative stress and oxidative modification of lipids in pathogenesis of psoriasis . 
 methods . the study group included 84 patients with psoriasis , and 40 sex- and age - matched healthy volunteers . 
 blood lipid profile was determined . 
 psoriatic and nonlesional skin samples of psoriatic patients were evaluated for the presence of oxidized low - density lipoprotein by using an immune - fluorescent staining method . 
 results . 
 the mean levels of lipids ( total cholesterol , triglyceride , and ldl cholesterol ) in patients with psoriasis were found to be significantly higher than those of healthy subjects .   
 psoriatic skins were shown positive oxidized low - density lipoprotein staining . 
 there was no staining in nonlesional skin samples of the same individuals . 
 conclusion . 
 lipid peroxidation mediated by free radicals is believed to be one of the important causes of cell membrane destruction and cell damage . 
 this study shows for the first time the accumulation of oxidized low - density lipoprotein in psoriatic skin lesion . 
 we believe that accumulation of ox - ldl in psoriatic skin may have an important role in the immune - inflammatory events that result in progressive skin damage . 