Marija Grdić Rajković

Effect of non-genetic factors on paraoxonase 1 activity in patients undergoing hemodialysis

OBJECTIVES Hemodialyzed patients have lower paraoxonase 1 (PON1) activity. Higher mortality risk from cardiovascular disease observed in these patients could be due to the low antiathetrogenic activity of PON1. Understanding the mechanism that causes lower PON1 activity could provide the possibility for modulation of enzyme activity in purpose of preventing and/or decreasing development of atherosclerosis. DESIGN AND METHODS 87 healthy individuals and 71 hemodialyzed patients were enrolled in this study. RESULTS Hemodialyzed patients had reduced PON1 paraoxonase and arylesterase activity, concentrations of HDL, HDL(3) and HDL(2) and concentrations of free thiol groups. Distribution of HDL subfractions and distribution of PON1 phenotypes as well as concentrations of MDA were not different between two study groups. In the in vitro experiment high concentrations of urea, creatinine, uric acid and addition of patients sera ultrafiltrate did not significantly affect PON1 paraoxonase activity. CONCLUSION Decreased HDL concentration as well as lower PON1 concentration (shown indirectly by the enzyme arylesterase activity) might contribute, at least partly, to the reduced PON1 activity observed in hemodialyzed patients. Decreased concentration of free thiol groups in sera suggest that free thiol group (Cys284) in PON1 might also be oxidized, which can affect PON1 activity.

Paraoxonase 1 Activity in Patients with Chronic Obstructive Pulmonary Disease

Abstract Introduction: Paraoxonase 1 (PON1) is an antioxidative enzyme manly associated with high density lipoproteins (HDL) in the peripheral blood. The aim of this study was to determine the PON1 paraoxonase and arylesterase activities in patients with chronic obstructive pulmonary disease (COPD). We also aimed to determine the concentration of reduced thiol groups as a marker of protein oxidation. Materials and methods: The study included 105 patients with stable COPD and 44 healthy controls. PON1 activities and thiols concentration were assayed in sera by spectrophotometry. Results: PON1 basal (POX) and salt-stimulated paraoxonase activity (POX1) as well as arylesterase activity (ARE) were significantly reduced in COPD patients. In addition, concentration of reduced thiol groups was significantly decreased in COPD group. PON1 activities were similar in patients with different disease severity (GOLD stages). However, a significant reduction in POX, POX1 and ARE was observed already in GOLD II stage when compared to controls. POX and POX1 showed modest while ARE yielded very good power for discrimination between healthy subjects and COPD patients. Univariate and multivariate logistic regression analysis indicated that ARE is a good COPD predictor. Conclusion: Reduction of PON1 activity observed in COPD patients could be partly caused by oxidative environment. Lower concentrations of reduced thiol groups in COPD patients suggest that a decrease in PON1 activity could reflect oxidative changes of enzyme free cysteine residues. Furthermore, decreased PON1 arylesterase activity might indicate a down-regulation of PON1 concentration. Our results suggest that ARE could be considered as potential biomarker for COPD diagnosis.

Polymorphisms of pon1 and pon2 genes in hemodialyzed patients

OBJECTIVES Q192R, L55M and -108C>T polymorphisms of pon1 gene affect PON1 paraoxonase activity while S311C polymorphism of pon2 gene might be associated with coronary heart disease. The aims of this study were to determine the frequencies of Q192R, L55M, -108C>T and S311C polymorphisms in hemodialyzed patients and to examine the relationship between pon1 gene polymorphisms and PON1 paraoxonase activity in those patients. DESIGN AND METHODS The study included 238 control subjects and 263 hemodialyzed patients. RESULTS PON1 paraoxonase activity was lower in patients. Genotype frequencies were different between two compared groups only for L55M polymorphism, with control group having higher frequency of MM genotype. Polymorphisms of pon1 gene were associated with significant variation in PON1 paraoxonase activity in both study groups. CONCLUSION Our results suggest that Q192R, L55M and -108C>T polymorphisms are not by itself the causal factors leading to the lower PON1 paraoxonase activity in hemodialyzed patients.

Paraoxonase 1 activity and phenotype distribution in premenopausal and postmenopausal women

Introduction Postmenopausal women have higher risk of cardiovascular disease. One of the contributing factors could be reduced activity of anti-atherogenic enzyme paraoxonase 1 (PON1). The aim of this study was to examine differences in the lipid status, paraoxonase and arylesterase PON1 activities and PON1 phenotype in women with regular menstrual cycle and in postmenopausal women. Materials and methods: The study included 51 women in reproductive age (25 in follicular and 26 in luteal phase of the menstrual cycle) and 23 women in postmenopause. Lipid parameters in sera were determined using original reagents and according to manufacturer protocol. PON1 activity in serum was assessed by spectrophotometric method with substrates: paraoxon and phenylacetate. PON1 phenotype was determined by double substrate method. Results: Compared to the women in follicular and luteal phase, postmenopausal women have significantly higher concentration of triglyceride [0.9 (0.7–1.3), 0.7 (0.6–1.0) vs. 1.5 (0.9–1.7) mmol/L; P = 0.002], cholesterol [5.10 (4.78–6.10), 5.05 (4.70–5.40) vs. 6.30 (5.73–7.23) mmol/L; P < 0.001], LDL [3.00 (2.56–3.63), 3.00 (2.70–3.70) vs. 3.90 (3.23–4.50) mmol/L; P < 0.001], and apolipoprotein B [0.88 (0.75–1.00), 0.79 (0.68–1.00) vs. 1.07 (0.90–1.24) mmol/L; P = 0.002]. PON1 basal [104 (66–260), 106 (63–250) vs. 93 (71–165) U/L; P = 0.847] and salt-stimulated paraoxonase activity [210 (131–462), 211 (120–442) vs. 180 (139–296) U/L; P = 0.857] as well as arylesterase activity [74 (63–82), 70 (54–91) vs. 70 (60–81) kU/L; P = 0.906] and PON1 phenotype (P = 0.810) were not different in the study groups. Conclusion: There are no differences in PON1 activity and PON1 phenotype between women with regular menstrual cycle and postmenopausal women.

Paraoxonase Polymorphisms and Platelet Activating Factor Acetylhydrolase Activity as a Genetic Risk Factors in Cerebral Atherosclerosis

The results of the present study show that basal and stimulated PON1 activities were significantly decreased in patient’s group with cerebrovascular stenosis ( group of patients with symptoms of cerebrovascular insufficiency and stenosis of carotid artery more than 50% of the lumen) versus control no-stenosis group (p 0.05. According to the obtained results the decreased PON1 activities in patients with cerebrovascular stenosis may cause decreased HDL antioxidant capacity and therefore contribute to the increase risk of the development of cerebrovascular atherosclerosis.However, there were no significant differences in genotype or allele frequencies of pon1 and pon2 genes between patients with stenosis of cerebral arteries and no-stenosis control group indicating that changes in paraoxonase activity are determined by both genetic and environmental factors. Our results show the most significant linear relationship between PAF-AH activity and total cholesterol and LDL-cholesterol ( p 0, 05) while LDL standardized PAF-AH activity showed significant difference between both examined groups (p<0.0001). According to our results the LDL-standardized PAF-AH activity could be used as an additional discriminating biochemical indicator of cerebrovascular stenosis.

Pro-inflammatory effects of extracellular Hsp70 and cigarette smoke in primary airway epithelial cells from COPD patients

Extracellular Hsp70 (eHsp70) can activate immune cells via Toll-like receptors (TLR) 2 and 4, and induce cytokine synthesis. The aim of this study was to explore inflammation-associated effects of eHsp70 alone and in combination with cigarette smoke extract (CSE) in primary bronchial epithelial cells. We assessed IL-6 and IL-8 concentrations, TLR2, TLR4 and Hsp70 mRNA expressions, and mitogen-activated protein kinases (MAPKs) activation induced by recombinant human (rh) Hsp70, CSE or their combinations in normal human bronchial epithelial cells (NHBE) obtained commercially, and primary bronchial epithelial cells isolated from non-COPD lung donors (PBEC) or COPD patients (PBEC COPD). Baseline levels of IL-6 and IL-8 were significantly higher in PBEC COPD than in non-COPD PBECs. Upon rhHsp70 stimulation, IL-6 and IL-8 were significantly increased, with the strongest response in COPD-derived PBECs. CSE alone elevated cytokine secretion in all examined cells. rhHsp70 and CSE had antagonistic interactions on IL-8 release in PBECs from COPD patients, while the addition of rhHsp70 further increased CSE-induced IL-6 secretion in NHBE cells. rhHsp70 and CSE alone decreased TLR2 and TLR4 mRNA expression in COPD-derived PBECs. In non-COPD PBECs, combined treatments decreased only TLR2 mRNA expression. Hsp70 mRNA expression, as indicator of intracellular Hsp70, which may have anti-inflammatory effects, was reduced in COPD-derived cells upon exposure to CSE and rhHsp70 alone, but not with their combinations. Contrary to this, in PBECs from lung donors only combined treatments supressed Hsp70 gene expression. CSE activated JNK and p38 MAPKs, while rhHsp70 increased activation of c-Jun kinase in NHBE cells. Collectively, both eHsp70 and CSE induce pro-inflammatory responses in PBECs from non-COPD as well as COPD donors, but in combination antagonistic effects were observed in COPD-derived cells. These effects may be related to the regulation of TLR2/4 and might lead to modulation of inflammation with possible deleterious consequences for COPD patients.

PON1 gene polymorphisms in patients with chronic obstructive pulmonary disease

Aims Chronic obstructive pulmonary disease (COPD) is characterised with oxidative stress. Paraoxonase 1 (PON1) is an enzyme, coded by PON1 gene, with distinctive antiatherogenic and antioxidative roles. We aimed to investigate the frequencies of Q192R, L55M and −108C>T polymorphisms and association of those polymorphisms with paraoxonase and arylesterase activities in patients with COPD. Methods PON1 genotype was determined by PCR–restriction fragment length polymorphism method. PON1 activity was measured by paraoxon and phenylacetate. Results Only −108C>T polymorphism resulted in significantly different distribution of genotypes and alleles, with higher frequency of TT genotype and T allele in patients compared with control subjects. Moreover, T allele (OR 2.29 (95% CI 1.54 to 3.41); p<0.001) as well as TT genotype (OR 5.00 (95% CI 2.19 to 11.43); p<0.001) showed an association with the disease. −108C>T polymorphism was suggested as a significant diagnostic predictor for the disease (OR (95% CI) 2.65 (1.53 to 4.59), p=0.001), with an area under the receiver operating characteristic curve of 0.90 (95% CI 0.84 to 0.93) and with 83.90% of correctly classified cases. Conclusions Higher frequency of TT genotype and T allele could contribute to the observed reduction of PON1 activity in patients with COPD. T allele and TT genotype are associated with COPD, and the PON1−108C>T polymorphism could be a potential predictor of the disease.

Authors' Reply: Evaluation of Paraoxonase 1 Activity in Chronic Obstructive Pulmonary Disease.

Authors’ Reply: Evaluation of Paraoxonase 1 Activity in Chronic Obstructive Pulmonary Disease Lada Rumora, Tihana Žanić Grubišić & Marija Grdić Rajković To cite this article: Lada Rumora, Tihana Žanić Grubišić & Marija Grdić Rajković (2015) Authors’ Reply: Evaluation of Paraoxonase 1 Activity in Chronic Obstructive Pulmonary Disease, COPD: Journal of Chronic Obstructive Pulmonary Disease, 12:4, 470-471, DOI: 10.3109/15412555.2014.995757 To link to this article: http://dx.doi.org/10.3109/15412555.2014.995757