Serum paraoxonase activity is decreased in the active stage of Behçet's disease

Paraoxonase 1 (PON1) gene Q192R polymorphism in patients with vitiligo

Background/Aim: Vitiligo is a prevalent inflammatory illness that can affect the skin and mucosal surfaces and is characterized by patchy loss of skin pigmentation. Paraoxonase1 (PON1) is an esterase enzyme with antioxidant properties that binds to high-density lipoproteins. We examined whether the PON1 gene Q192R polymorphism is a risk factor for vitiligo among Turkish people. Methods: The study included 70 controls and 60 vitiligo cases. Polymerase chain reaction and the restriction fragment length polymorphism technique were used to genotype the PON1 gene Q192R polymorphism. Results: PON1 gene Q192R genotype distribution was 66.7% QQ, 33.3% QR, and 0% RR in the vitiligo and 81.4% QQ, 18.6% QR, and 0% RR in the control (P = 0.05). When vitiligo patients were compared with controls, the prevalence of the PON1 QR genotype was substantially higher and was linked to a 2.19-fold greater risk of developing vitiligo (odds ratio: 2.19, 95% confidence interval (CI): 0.97–4.91). Conclusion: These findings imply that Q192R polymorphisms in the PON-1 gene may be linked to vitiligo in the Turkish population. The PON1 QR genotype may be a major genetic risk factor for vitiligo susceptibility and progression. Further studies with larger populations should more thoroughly clarify the association.

Comparison of Oxidant and Antioxidant Parameters in Patients with Sjögren’s Syndrome and Healthy Subjects

Objective Oxidative stress may have an effect on the pathogenesis of diseases, including autoimmune rheumatic diseases. We aimed to investigate the serum paraoxonase activity and other oxidant/antioxidant parameters in patients with Sjögren’s syndrome (SS) and healthy controls.

Methods 85 patients with SS and 65 healthy subjects were included in the study. Groups were age and gender-matched and had no liver disease. Serum paraoxonase (PON)-1 activity, stimulated paraoxonase (SPON), PON-1 phenotypes that represent polymorphism (Q192R; QQ, QR, RR), arylesterase (ARE), total oxidant status (TOS), total antioxidant capacity (TAC), oxidative stress index (OSI), advanced oxidative protein products (AOPP), total thioles (TTL) and ischaemia-modified albumin (IMA) were measured in all study participants.

Results Statistically significant differences were found in the QQ and QR+RR phenotype of PON-1 for TAC, TOS and TTL (p<0.001) between SS and healthy groups. The other parameters were statistically insignificant.

Conclusion Antioxidant parameters were lower in SS patients compared with healthy controls. Conversely, oxidant parameters were higher. This imbalance may play a role in SS pathogenesis.

Paraoxonase and Arylesterase Levels in Behcet's Disease and Their Relations with the Disease Activity

The aim of this study was to determine the paraoxonase (PON) and arylesterase (ARE) enzyme activity levels in Behcet's disease (BD) and to investigate whether they are associated with the disease activity. Twenty-six patients (study group) with active BD and 28 healthy controls (control group) were included in this study. While the patients who had at least one of the symptoms related to genital ulcer, skin lesions, active uveitis, arthritis, thrombophlebitis, or central nervous system involvement in addition to oral ulcers were considered as the active group, the patients who did not show clinical symptoms in the last one month due to the medical treatment were considered as the inactive group in the clinical evaluation of patients with BD. The PON and ARE levels were found to be significantly lower in the study group than the control group (p < 0.05). The PON levels of the active and inactive groups were 96.23 ± 57.84 and 112.2 ± 65.14, respectively. The ARE levels of the active and inactive groups were 30.49 ± 5.81 and 30.85 ± 6.40, respectively. No significant correlations were found between clinical findings and the activity levels of PON and ARE in the active patient group (p > 0.05). The activities of the antioxidant PON and ARE enzymes are reduced in BD. Therefore, it may be useful to add antioxidant therapy to the conventional treatment of the disease.

Serum paraoxonase activity and oxidative stress levels in patients with cutaneous anthrax

INTRODUCTION

Anthrax is a bacterial disease caused by the aerobic sporeforming bacterium Bacillus anthracis. It has been suggested that oxidative stress plays an important role in the pathogenesis of B. anthracis. The aim of this study was to investigate serum paraoxonase 1 (PON1) activity, catalase activity, malondialdehyde (MDA) levels, and superoxide dismutase (SOD) levels in patients with cutaneous anthrax.

MATERIALS AND METHODS

Fifteen patients with cutaneous anthrax and 15 healthy controls were enrolled in this study. The serum MDA levels, SOD levels, paraoxonase, arylesterase, and catalase activities were measured using a spectrophotometer.

RESULTS

The serum SOD levels, paraoxonase, arylesterase, and catalase activities were significantly lower in patients with cutaneous anthrax than in controls (for all, p < 0.001), whereas MDA levels were significantly higher ( p < 0.001). No significant correlation was found between serum paraoxonase activity, arylesterase activity, SOD levels, and MDA levels (all, p > 0.05) in patients with cutaneous anthrax.

CONCLUSIONS

The current study was the first to show decreased antioxidant levels and increased oxidant levels in patients with cutaneous anthrax. Therefore, decreased PON1 activity may play a role in the pathogenesis of cutaneous anthrax.

Oxidative stress in otosclerosis

OBJECTIVES

Otosclerosis is a disease involving abnormal bone turnover in the human otic capsule that results in hearing loss. Several hypotheses have been suggested for the etiopathogenesis of otosclerosis; however, its etiology remains unclear.

METHODS

This study evaluated the correlation between otosclerosis and levels of paraoxonase-1 (PON1), arylesterase, total antioxidant status, total oxidant status (TOS), oxidative stress index (OSI), total sulfhydryl (-SH) groups, lipid hydroperoxide, and ceruloplasmin in the serum of otosclerosis patients and healthy subjects with respect to oxidative stress.

RESULTS

In our study, TOS and OSI levels were higher in the otosclerosis patients than in the controls. The PON1 levels showed that oxidative stress was severe, and as a result, antioxidants were consumed and depleted.

DISCUSSION

When an imbalance between oxygen free radical production and antioxidative defense mechanisms occurs, reactive oxygen species levels may increase, which in turn may damage cells and tissues through the peroxidation of phospholipid membrane structures. The body initially responds with increased antioxidant production, but if the oxidative stress is severe, decreased antioxidant levels may result. This study reports expression levels of oxidative stress species in otosclerosis patients.

Total oxidative stress, paraoxonase and arylesterase levels at patients with pseudoexfoliation syndrome and pseudoexfoliative glaucoma

AIM

To investigate the oxidative stress status of the aqueous humor and serum of patients with pseudoexfoliation (PEX) syndrome and pseudoexfoliative glaucoma (PEG) and to measure paraoxonase (PON) and arylesterase (ARE) levels.

METHODS

A total of 78 patients were enrolled in the study, with 26 patients in each separate group. The patients were divided into three groups: the first group entailed PEX syndrome patients, while the second group consisted of patients with PEG and the third group involved patients with no additional systemic diseases, other than the diagnosis of cataract as control. Total oxidative stress (TOS), total antioxidant capacity (TAC), PON, and ARE levels in aqueous humor and serum were measured.

RESULTS

TAC, PON and arylesterase levels in aqueous humor and serum of the PEX syndrome and PEG patients were significantly decreased compared with control group (P<0.05). TOS values were higher in patients with PEX syndrome and PEG than controls (P<0.05). TAC, PON and ARE levels of aqueous humor did not differ significantly between the PEX syndrome and PEG groups.

CONCLUSION

These findings are potentially of significance and add to the growing body of evidence for oxidative stress in PEX syndrome and PEG. Decreased antioxidant defense and increased oxidative stress system may play an important role in the pathogenesis of PEX syndrome and PEG.

Serum paraoxonase and arylesterase activities in patients with chronic otitis media

OBJECTIVES

Paraoxonase-1 (PON1) prevents oxidative stress by inhibiting the oxidation of cell membrane lipids by the reactive oxygen species that form during acute and chronic inflammation. The aim of this study was to investigate serum PON1 activity and oxidative stress in patients with chronic otitis media (COM).

METHODS

Fifty consecutive patients with COM and 55 controls were enrolled in the present study. The patients were divided into two groups according to the presence of cholesteatoma. The serum PON1 arylesterase activities and lipid hydroperoxide (LOOH) levels were determined.

RESULTS

Serum paraoxonase and arylesterase activities were significantly lower in the COM patients than in the controls (P < 0.001 for all comparisons), whereas the LOOH levels were significantly higher (P < 0.001).

DISCUSSION

These results indicated that a lower level of PON1 activity was associated with an oxidant-antioxidant imbalance. In addition, decreased PON1 activity may play an important role in the pathophysiology of COM.

Serum paraoxonase activity, total thiols levels, and oxidative status in patients with acute brucellosis

It is well known that paraoxonase-1 (PON1) activity may decrease during the course of infection and inflammation. The aim of this study was to investigate serum PON1 activity, oxidative status, and thiols levels in patients with acute brucellosis. In addition, we investigated the PON1 phenotype in patients with acute brucellosis. Thirty patients with acute brucellosis and 35 healthy controls were enrolled. Serum paraoxonase and arylesterase activities, thiols levels, lipid hydroperoxide levels, total antioxidant capacity (TAC), total oxidant status (TOS) and oxidative stress index (OSI) were determined. Serum basal and salt-stimulated paraoxonase-arylesterase activities, TAC levels and thiols levels were significantly lower in patients with acute brucellosis than controls (for all, p < 0.05), while LOOH levels, TOS levels, and OSI values were significantly higher (for all, p < 0.05). We concluded that oxidative stress is increased, while serum PON1 activity is decreased in patients with acute brucellosis. These results indicate that lower PON1 activity is associated with oxidant-antioxidant imbalance.

PEP-1-PON1 protein regulates inflammatory response in raw 264.7 macrophages and ameliorates inflammation in a TPA-induced animal model

Paraoxonase 1 (PON1) is an antioxidant enzyme which plays a central role in various diseases. However, the mechanism and function of PON1 protein in inflammation are poorly understood. Since PON1 protein alone cannot be delivered into cells, we generated a cell permeable PEP-1-PON1 protein using protein transduction domains, and examined whether it can protect against cell death in lipopolysaccharide (LPS) or hydrogen peroxide (H₂O₂)-treated Raw 264.7 cells as well as mice with 12-O-tetradecanoyl phorbol-13-acetate (TPA)-induced skin inflammation. We demonstrated that PEP-1-PON1 protein transduced into Raw 264.7 cells and markedly protected against LPS or H₂O₂-induced cell death by inhibiting cellular reactive oxygen species (ROS) levels, the inflammatory mediator’s expression, activation of mitogen-activated protein kinases (MAPKs) and cellular apoptosis. Furthermore, topically applied PEP-1-PON1 protein ameliorates TPA-treated mice skin inflammation via a reduction of inflammatory response. Our results indicate that PEP-1-PON1 protein plays a key role in inflammation and oxidative stress in vitro and in vivo. Therefore, we suggest that PEP-1-PON1 protein may provide a potential protein therapy against oxidative stress and inflammation.

Serum paraoxonase activity and oxidative status in subjects with alopecia areata

INTRODUCTION

Previous studies have suggested that oxidative stress may play an important role in the pathogenesis of alopecia areata (AA) but these reports are limited and conflicting.

OBJECTIVES

The aim of this study was to investigate serum paraoxonase-1 (PON1) activity and oxidative status in subjects with AA.

MATERIALS AND METHODS

Thirty-nine subjects with AA and 39 healthy controls were enrolled. Serum PON1 activity, total antioxidant capacity (TAC), total oxidant status (TOS) and oxidative stress index (OSI) were determined.

RESULTS

Serum TAC levels and PON1 activity were significantly lower in the subjects with AA than controls (p = 0.038, p = 0.001, respectively), whereas TOS levels and OSI were significantly higher (both, p = 0.001) in the subjects with AA.

CONCLUSIONS

Our results suggest that reduced PON1 activity may be related to increased oxidant and decreased antioxidant levels. These data indicated that oxidant/antioxidant imbalance may play a role in the etiopathogenesis of AA.

Reduced serum paraoxonase-1 levels in vitiligo: further evidence of oxidative stress

Vitiligo is a common disorder that results in depigmented areas of the skin. The pathogenesis of the disease remains unclear, but oxidative stress is one suggested cause. Oxidative stress may be induced by increasing the generation of reactive oxygen species and other free radicals. The generation of reactive oxygen species is known to be associated with a decrease in antioxidant levels. This study examined oxidative stress index in active lesions of generalized vitiligo patients. We analysed serum levels of paraoxonase 1, arylesterase, catalase, ceruloplasmin, total antioxidant capacity, and oxidative stress index in patients with active lesions of generalized vitiligo, as well as in matched, healthy controls. Serum oxidants and oxidative stress indexes were higher, and serum antioxidants were lower, in vitiligo patients compared with healthy controls. Our findings suggest that oxidative stress may play an important role in the pathogenesis of vitiligo. Paraoxonase 1 can be used as an indicator in determining oxidative stress existent in the pathogenesis of vitiligo diseases.

Oxidative stress in chronic otitis media

Chronic otitis media usually presents with a benign tumor-like lesion of the temporal bone known as a cholesteatoma. The role of oxidative stress in the pathogenesis of chronic otitis media and cholesteatoma has not yet been fully explored. Therefore, the aim of this study was to investigate the oxidative stress markers and antioxidant enzymes in patients with cholesteatomatous and noncholesteatomatous chronic otitis media and in healthy subjects. A prospective controlled trial was performed on cholesteatomatous and noncholesteatomatous chronic otitis media patients in a tertiary referral center in a university hospital. A total of 75 subjects, including 25 cholesteatomatous and 25 noncholesteatomatous chronic otitis media patients and 25 healthy subjects participated in this study. Serum total oxidant status (TOS) and oxidative stress index (OSI) levels were significantly increased in the patient groups with or without cholesteatoma compared with the control group. Serum total antioxidant status (TAS) levels and Paraoxonase and arylesterase activity were significantly lower in the patient groups with or without cholesteatoma compared with the control group. Serum TOS and OSI levels were lower in the noncholesteatomatous group, whereas serum TAS levels were higher compared with the cholesteatomatous group. Serum arylesterase activity was significantly lower in the noncholesteatomatous group compared with the control group. The results of this study reveal that in cholesteatoma cases, the oxidative stress and antioxidant enzyme imbalance were more significant than in cases of chronic otitis media without cholesteatoma.

Paraoxonase and arylesterase activity and total oxidative/anti-oxidative status in patients with chronic adenotonsillitis

OBJECTIVES

The aim of this study was to investigate serum paraoxonase, arylesterase activities along with determination of oxidative status via measurement of total oxidant status (TOS), total antioxidant status (TAS) and oxidative stress index (OSI) in children with recurrent adenotonsillitis during pre- and post-adenotonsillectomy period and to compare results with data from healthy subjects.

METHODS

We performed a prospective controlled trial on adenoidectomy and/or tonsillectomy patients. A total of 47 subjects, including 22 patients with recurrent adenotonsillitis and 25 healthy controls were enrolled in this study. Peripheral venous blood samples were taken from patients before adenotonsillectomy and a second sample was obtained in first month postoperatively. In the control group, blood samples from healthy volunteers were collected for one time only. Serum paraoxonase, arylesterase activities, TOS, TAS and OSI levels were measured.

RESULTS

Paraoxonase, arylesterase activity, TAS and TOS levels were significantly higher in preoperative group compared to control group (P<0.001, P=0.003, 0.003 and 0.005, respectively). However, OSI level was similar in preoperative group compared to control group (P=0.25). In the post-operative group, paraoxonase, arylesterase activities, TAS and OSI levels were lower as compared to preoperative group but differences were statistically insignificant (P=0.483, 0.265, 0.149 and 0.090, respectively). TOS level in post-operative group was significantly lower than the preoperative group (P<0.001). In the post-operative group, paraoxonase and arylesterase activities were significantly higher as compared to control group (P=0.004 and 0.02, respectively). TOS and OSI levels were significantly lower in post-operative group compared to control group (P=0.001 and 0.02, respectively). However, TAS was similar between post-operative and control groups (P=0.464).

CONCLUSIONS

Based on data obtained from this study, we may state that paraoxonase, arylesterase activities with TAS, TOS and OSI levels of patients with chronic adenotonsillitis shows alterations due to oxidant/antioxidant imbalance induced by frequent infections.

Assessment of serum homocysteine, endothelin-1, and nitric oxide levels in behçet's disease

BACKGROUND

Some prominent features of Behçet's disease (BD) are arterial and venous thromboses as a result of endothelial dysfunction. Hyperhomocysteinemia is responsible for vascular endothelial injury due to an increased frequency of thrombogenesis. Endothelin-1 (ET-1) is a vasoconstrictor whereas nitric oxide (NO) is an endothelial vasorelaxing peptide that is responsible for the inhibition of platelet adhesion.

AIM

To evaluate serum levels of homocysteine (Hcy) and determine whether hyperhomocysteinemia is considered as a contributing risk factor for venous and arterial thromboses of BD, and to correlate serum levels of ET-1 and NO with disease activity.

MATERIALS AND METHODS

We measured serum levels of Hcy, ET-1, and nitrite (NO(2) (-)) in 25 patients who fulfilled the criteria of the International Study Group for BD, and compared them to those of 15 healthy control subjects. Levels of Hcy and ET-1 were measured by using enzyme-linked immunosorbent assay (ELISA), whereas serum nitrite (NO(2) (-)) levels were measured by using Griess reaction as an indicator for NO production. All the patients were screened for a history of venous thrombosis and subdivided into thrombotic and nonthrombotic subgroups according to their thrombotic history. Patients with BD were divided into two subgroups, active and inactive, according to their clinical and laboratory findings.

RESULTS

There were significant increases in serum levels of Hcy, ET-1, and nitrite in BD patients compared to those in controls. There was a significant increase in serum Hcy levels in thrombotic compared to nonthrombotic subgroups. Positive correlations were detected between the serum ET-1 and nitrite levels with disease activity in BD patients.

CONCLUSION

Hyperhomocysteinemia may play some role in the development of venous and arterial thromboses in BD. Increased NO production might ave critical biological activities that are relevant to pathological events in the active period of the disease.

Evaluation of serum paraoxonase and arylesterase activities in ankylosing spondylitis patients

OBJECTIVES

The aim of this study was to investigate the activities of serum paraoxonase and arylesterase in patients with ankylosing spondylitis with respect to those of healthy controls, to assess whether these enzyme levels are related to disease activity and functional capacity.

METHODS

The study included 32 patients with ankylosing spondylitis whose diagnoses were made according to the modified New York criteria as well as 25 healthy controls matched for age and sex. The Bath Ankylosing Spondylitis Disease Activity Index and the Bath Ankylosing Spondylitis Functional Index were applied to the ankylosing spondylitis patients. As laboratory parameters, the erythrocyte sedimentation rate and serum C-reactive protein level were measured in patients and control subjects. Paraoxonase and arylesterase enzyme activities were measured using appropriate methods.

RESULTS

No statistically significant differences (p>0.05) were found between the ankylosing spondylitis patients and controls in terms of serum paraoxonase or arylesterase levels. Furthermore, there was no correlation between clinical and laboratory parameters in patients with ankylosing spondylitis.

CONCLUSION

Serum paraoxonase and arylesterase levels in ankylosing spondylitis patients may not differ from those of healthy controls, and there is no significant correlation between antioxidant parameters and the Bath Ankylosing Spondylitis Disease Activity Index or Bath Ankylosing Spondylitis Functional Index scores in ankylosing spondylitis patients. Further research is needed to provide deeper understanding of this disease.

Paraoxonase: a multifaceted biomolecule

BACKGROUND

Paraoxonase enzyme was first identified as a protective barrier against organophosphorus poisoning. After painstaking research spanning the last three decades, the knowledge about this enzyme has increased immensely. The present review attempts to elaborate the role of paraoxonase enzyme in normal physiology as well as provide an overview of the various disorders in which the enzyme may have a role in etiopathogenesis.

METHODS

The literature was searched from the websites of the National Library of Medicine (http://www.ncbi.nlm.nih.gov/) and Pub Med Central, the U.S. National Library of Medicine's digital archive of life sciences journal literature.

RESULTS

Paraoxonase acts as an important antioxidant enzyme against oxidative stress. The enzyme has been implicated in the pathogenesis of a number of disorders including cardiovascular disorders, cancers etc.

CONCLUSIONS

A better understanding of the molecular mechanism of the enzyme along with the regulatory circuits will help us to utilize agonists to potentiate the anti oxidant actions of the enzyme.

Drosophila are protected from Pseudomonas aeruginosa lethality by transgenic expression of paraoxonase-1

Pseudomonas aeruginosa uses quorum sensing, an interbacterial communication system, to regulate gene expression. The signaling molecule N-3-oxododecanoyl homoserine lactone (3OC12-HSL) is thought to play a central role in quorum sensing. Since 3OC12-HSL can be degraded by paraoxonase (PON) family members, we hypothesized that PONs regulate P. aeruginosa virulence in vivo. We chose Drosophila melanogaster as our model organism because it has been shown to be a tractable model for investigating host-pathogen interactions and lacks PONs. By using quorum-sensing-deficient P. aeruginosa, synthetic acyl-HSLs, and transgenic expression of human PON1, we investigated the role of 3OC12-HSL and PON1 on P. aeruginosa virulence. We found that P. aeruginosa virulence in flies was dependent upon 3OC12-HSL. PON1 transgenic flies expressed enzymatically active PON1 and thereby exhibited arylesterase activity and resistance to organophosphate toxicity. Moreover, PON1 flies were protected from P. aeruginosa lethality, and protection was dependent on the lactonase activity of PON1. Our findings show that PON1 can interfere with quorum sensing in vivo and provide insight into what we believe is a novel role for PON1 in the innate immune response to quorum-sensing-dependent pathogens. These results raise intriguing possibilities about human-pathogen interactions, including potential roles for PON1 as a modifier gene and for PON1 protein as a regulator of normal bacterial florae, a link between infection/inflammation and cardiovascular disease, and a potential therapeutic modality.

Relationship between thiolactonase activity and hyperhomocysteinemia according to MTHFR gene polymorphism in Tunisian Behçet's disease patients

BACKGROUND

Behçet's disease (BD) is a multisystemic immuno-inflammatory disorder. Inflammatory processes may cause lipid peroxidation, alteration of lipid profile and increase the risk of atherosclerosis. The aim of this study was to evaluate the association between thiolactonase (HTLase) activity and plasma homocysteine levels (tHcy) in a BD population and to investigate their association with methylenetetrahydrofolate reductase (MTHFR) 677C-->T genotype.

METHOD

A total of 35 BD patients were compared to 39 healthy volunteers.

RESULTS

Significantly higher tHcy levels associated with lower HTLase activities were found in BD patients as compared to healthy controls (p<0.001). These patients also exhibited lower values of triglycerides and high-density lipoprotein cholesterol (HDL-C). Homozygosity for the T allele of the MTHFR gene was more frequent in BD patients (14.3% vs. 7.7%). It was associated with significantly higher tHcy levels (16.9 micromol/L for n=17 vs. 13.1 micromol/L for n=18; p<0.05) and markedly lower HTLase activity (362.6+/-156.7 U/L vs. 414.2+/-180.2 U/L) for the (TT+CT) and CC genotypes, respectively. Moreover, HDL-C levels were inversely correlated with tHcy (r=-0.5; p=0.004) but positively associated with HTLase activity (r=0.374; p=0.038). These correlations were also present in several clinical manifestations, such as ocular, neurological involvement or thrombosis.

CONCLUSIONS

Homozygosity of the T allele of the MTHFR gene is prevalent in BD patients. High levels of tHcy associated with low HTLase activities may be one of the causes leading to thrombosis in BD patients.

Serum paraoxonase undergoes inhibition and proteolysis during experimental acute pancreatitis

Oxidative stress has a primary role in the pathogenesis of severe acute pancreatitis. Then, the antioxidant capacity is a critical factor in the progression of this disease. Serum paraoxonase-1 (PON1) is an esterase associated with high-density lipoprotein, which clinical interest resides in its ability to prevent or limit the lipid oxidation. The aim of this study was to investigate changes in PON1 activity in the early stages of acute pancreatitis and to find out if its alteration is related with the severity of the disease. To this purpose, we used an experimental model of taurocholate-induced mild and severe acute pancreatitis. Our results showed that serum activity and PON1 concentration decreased 18 h after the induction of a severe acute pancreatitis. In vitro analysis revealed that incubation with oxidized lipids obtained from pancreatitis samples results in the inactivation of the enzyme in a concentration-dependent manner. In addition to oxidative inactivation, we observed by Western blot, an immunoreactive band suggestive of proteolytic degradation of the enzyme, altogether indicating that during severe acute pancreatitis, there is a significant decrease in serum PON1 activity. This decrease is related with inactivation of the enzyme by oxidized lipids, probably followed by proteolytic degradation of the enzyme.

Serum PON1 arylesterase activity in relation to hyperhomocysteinaemia and oxidative stress in young adult central retinal venous occlusion patients

AIM

To estimate the arylesterase activity of serum paraoxonase-1 (PON1-ARE), which is reported to have an antioxidant and antiatherogenic potential and to correlate with plasma homocysteine (Hcys) and plasma TBARS in young adult central retinal venous occlusion (CRVO) patients.

METHODS

A case-control prospective study carried out in 10 CRVO patients (mean age 27+/-5 years; 7 males, 3 females) and 20 healthy controls (mean age 29+/-5 years; 15 males, 5 females).

RESULTS

The CRVO patients showed a significantly lowered serum PON1-ARE activity (P=0.009) along with a significant increase in the levels of plasma Hcys (P=0.018) when compared to the control subjects. There was a negative correlation between serum PON1-ARE and plasma Hcys levels (P=0.058) as well as between PON1-ARE and plasma TBARS levels (P=0.001) in the CRVO patients.

CONCLUSION

This is the first report of lowered serum PON1-ARE level as a risk factor for CRVO (OR= 1.108, CI=0.914, 1.314; P=0.296), which is found to correlate with oxidative stress.

Serum oxidative-antioxidative status in patients with ankylosing spondilitis

Ankylosing spondylitis (AS) is an inflammatory disorder with unknown etiology that mainly affects the axial skeleton as well as the peripheral joints and extra-articular structures. The aim of this study was to evaluate the total antioxidant status (TAS), total oxidative status (TOS) and oxidative stress index (OSI) in patients with ankylosing spondylitis (AS). Fifty AS patients with a mean Bath AS Activity Index (BASDAI) 4.6 (range 4-9.3) and 26 healthy controls were included in the study. Plasma TAS, TOS levels were determined by using novel automated methods. The OSI was calculated. Plasma TOS level and OSI values were significantly higher, and plasma TAS level was lower in patients than in healthy controls (15.8 +/- 4. 9 vs. 4.3 +/- 2.8, 12.8 +/- 3. 9 vs. 9.6 +/- 5.5, 1.2 +/- 0.03 vs. 1.8 +/- 0.2, respectively, P < 0.001 for all). There was no significant correlation between oxidant/antioxidant parameters and disease activity. The results of this study indicated that increased oxidant and decreased antioxidant capacity may be associated with the pathogenesis of AS.

Oxidative stress and antioxidant defenses in serum of patients with non-alcoholic steatohepatitis

OBJECTIVES

Oxidative stress is an important pathophysiological mechanism in non-alcoholic steatohepatitis (NASH). We aimed to evaluate serum xanthine oxidase (XO) (as a generator of reactive oxygen species), superoxide dismutase (SOD), glutathione peroxidase (GSHPx), paraoxonase (PON1) activities, nitric oxide (NO) and thiol levels in patients with NASH.

DESIGN AND METHODS

A total of 35 patients with NASH and 31 age-and-gender-matched healthy subjects were enrolled in the study as control group. Serum levels of XO, NO, SOD, GSHPx, PON1 and thiol were determined by spectrophotometric methods.

RESULTS

Serum XO activities were higher in the patients with NASH than the controls (p<0.001). Serum NO levels, SOD, GSHPx, PON1 activities and thiol levels were lower in the patients with NASH than the controls (p<0.031, p<0.019, p<0.001, p<0.001, p<0.001, respectively).

CONCLUSIONS

Increased oxidative stress in patients with NASH may result in a pro-oxidation environment, which in turn could result in decreased antioxidant enzyme activities and NO levels. Therefore effective antioxidant therapy to inhibit oxidative stress is necessary and agents to increase antioxidant enzyme may be a therapeutic option in NASH.

Decreased Total Antioxidant Response and Increased Oxidative Stress in Behcet's Disease

Behcet's disease (BD) is a chronic systemic inflammatory disease. Inflammatory reactions trigger the oxidative stress and oxidants decrease the level of antioxidants. In the present study, we aimed to determine serum oxidative/antioxidative status in patients with BD. Serum antioxidative status was evaluated by measuring total antioxidant capacity (TAC), paraoxonase 1, arylesterase, sulfhydryl groups and ceruloplasmin in patients with BD and in healthy controls. Serum oxidative status was evaluated by measuring total peroxide (TP), lipid hydroperoxides and oxidative stress index (OSI). OSI was calculated by percent ratio of TP to TAC. Serum levels of TAC, sulfhydryl groups and activities of paraoxonase 1, arylesterase, and ceruloplasmin were significantly lower in patients than in controls (p < 0.001 for all). In contrast, TP, lipid hydroperoxides and OSI values were significantly higher in patients than in controls (p < 0.001 for all). Further, the level of TAC was negatively correlated with the levels of TP, lipid hydroperoxides and OSI both in the BD (r = -0.578, p < 0.01; r = -0.559, p < 0.01 and r = -0.552, p < 0.01, respectively) and the control groups (r = -0.469, p < 0.05; r = -0.351, p < 0.05 and r = -0.391, p < 0.05, respectively). These results indicate that the oxidant parameters increased and antioxidant parameters decreased in patients with BD; therefore, these patients might have been exposed to oxidative stress. We suggest that impaired oxidant/antioxidant balance should be taken into consideration in the follow-up of patients with BD.

Serum paraoxonase-1 activity in Helicobacter pylori infected subjects

Previous studies have suggested that Helicobacter pylori (H. pylori) infection may play an important role in the process of atherosclerosis. The objective of this study was to investigate serum paraoxonase and arylesterase activities, and lipid hydroperoxide (LOOH) and total thiol (SH) levels along with lipid parameters in H. pylori infected subjects. Fifty-six H. pylori positive subjects and 43 H. pylori negative subjects were enrolled. Serum paraoxonase and arylesterase activities were measured spectrophotometrically. LOOH levels were measured by FOX-2 assay. Serum SH levels, paraoxonase and arylesterase activities were significantly lower in H. pylori positive group than H. pylori negative group (all p<0.05), while LOOH levels were significantly higher (p<0.05). In H. pylori positive subjects, serum LOOH levels were correlated with SH levels (r=-0.247, p<0.05), serum paraoxonase (r=-0.432, p<0.05) and arylesterase activities (r=-0.404, p<0.001), and triglyceride (r=0.305, p<0.05), total cholesterol (r=0.568, p<0.05), high-density lipoprotein-cholesterol (HDL-C) (r=-0.300, p<0.05) and low-density lipoprotein-cholesterol (LDL-C) (r=0.577, p<0.05) levels. Serum paraoxonase and arylesterase activities were also correlated with HDL-C levels (r=0.221, p<0.05 and r=0.291, p<0.05, respectively), while no correlation was observed with triglyceride, total cholesterol and LDL-C levels (both p>0.05). In conclusion, paraoxonase and arylesterase activities decrease significantly in H. pylori infected subjects. Lower serum paraoxonase-1 (PON1) activity seems to be related to decrease in HDL-C and, in part, to increased oxidative stress and inflammatory condition induced by H. pylori infection. Measurement of serum PON1 activity may help in the early identification of H. pylori infected subjects with increased risk of atherosclerotic disease.

Increased DNA damage and oxidative stress in patients with rheumatoid arthritis

OBJECTIVES

Oxidative stress has been described as an important mechanism that underlies chronic inflammation in rheumatoid arthritis (RA). The aim of the study was to investigate the peripheral DNA damage, total antioxidant status (TAS), and total oxidative status (TOS) in patients with RA.

DESIGN AND METHODS

The study population contained 25 patients with RA and 26 healthy controls. DNA damage was assessed by alkaline comet assay in peripheral lymphocyte, plasma levels of total antioxidant status (TAS) and total oxidative status (TOS) were determined, and OSI was calculated using a novel automated measurement method. Disease activity was evaluated by DAS-28 score.

RESULTS

In RA patients, DNA damage was significantly higher than in controls (20.0+/-9.6 AU, 7.6+/-4.3 AU; p<0.001). Plasma TOS and OSI were higher in patients than in healthy controls (9.9+/-2.6 vs. 7.3+/-1.1, p<0.001; 1.04+/-0.4 vs. 0.7+/-0.1, p<0.001, respectively). Plasma TAS level in patients was lower than in healthy controls (0.9+/-0.7 vs. 1.01+/-0.7, p<0.001). DNA damage was correlated with TOS, OSI, and DAS-28 scores (r=0.682, p<0.001; r=0.753, p<0.001; r=0.519, p=0.008, respectively).

CONCLUSIONS

The findings indicated that lymphocyte DNA damage level increases in patients with RA. Elevated DNA damage may be related with increased oxidative stress and decreased antioxidant capacity. However, the mechanism of this association, and whether it is direct or indirect, remains to be explored.

Probucol up-regulates paraoxonase 1 expression in hepatocytes of hypercholesterolemic rabbits

Paraoxonase 1 (PON1), an HDL-associated enzyme, has anti-oxidative property. Probucol, a hydrophobic antioxidant drug, inhibits progression of atherosclerosis and post-angioplasty restenosis. However, the mechanism by which probucol affects atherosclerosis is not completely understood. Sixteen rabbits fed with high cholesterol diet for 8 weeks were randomly divided into two groups: (1) starch group (n = 8): maintained high cholesterol diet plus starch (500 mg/kg/d) for 6 weeks; (2) probucol group (n = 8): the same cholesterol diet plus probucol (500 mg/kg/d) for 6 weeks. Control group (n = 8) was fed with normal diet for 14 weeks. The classic in-situ two-step perfusion of the liver with collagenase IV was used to isolate the parenchymal hepatocytes. The total activity of superoxide dismutase (SOD) and malondialdehyde (MDA) and PON1 concentrations in serum were measured after 0, 8, and 14 weeks of feeding. Reverse transcription polymerase chain reaction (RT-PCR) was used to detect the mRNA expression of PON1. Compared with control group, rabbits fed with high cholesterol diet showed higher levels of serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C), all of which were significantly reduced by probucol. Probucol significantly decreased the MDA concentration but was ineffective on SOD activity. High cholesterol diet decreased serum PON1 concentration and down-regulated PON1 mRNA expression in hepatocytes. Probucol significantly increased serum PON1 level and up-regulated the mRNA expression of PON1 as compared with starch group (0.65 +/- 0.06 versus 0.46 +/- 0.05, P = 0.001). The PON1 concentration is negatively associated with MDA concentration (r = -0.86, P = 0.003) but not with the level of HDL-C. In conclusion, probucol decreased MDA concentration, and increased PON1 serum level as well as mRNA expression in hepatocytes, which may help us to understand its antioxidant and anti-atherogenic effects.

Assessment of paraoxonase 1 activity and malondialdehyde levels in patients with rheumatoid arthritis

OBJECTIVES

We aimed to evaluate antioxidant paraoxonase 1 activity together with malondialdehyde (MDA) (an oxidative stress parameter) levels in patients with rheumatoid arthritis.

DESIGN AND METHODS

Fifty-seven rheumatoid arthritis patients were included in the study and subgrouped according to disease activity (active, n = 31; inactive, n = 26) and compared with healthy controls (n = 25). Serum paraoxonase 1 activity and MDA levels were measured according to an enzymatic spectrophotometric method.

RESULTS

Serum MDA level was higher (P = 0.001) whereas paraoxonase 1 activity was lower (P = 0.001) in the patient group than the controls. When active and inactive subgroups were compared with the control group, there was a statistically significant difference between each parameter. Serum MDA levels were significantly higher, while paraoxonase 1 activity was lower in the active and inactive rheumatoid arthritis groups than the control group. But there was not any difference between active and inactive patients with RA. There was a negative correlation between MDA levels and paraoxonase 1 activity.

CONCLUSIONS

Increased reactive oxygen species levels in rheumatoid arthritis may result in a pro-oxidation environment, which in turn could result in decreased antioxidant paraoxonase 1 activity and increased MDA levels.