Paraoxonase 1 Paraoxonase Activities Research Articles

Effect of Exercise Repetitions on Arylesterase Activity of PON1 in Plasma of Average-Trained Men-The Dissociation between Activity and Concentration.

Exercise may increase the antioxidant capacity of plasma by stimulating antioxidant enzymes. The study aimed to measure the effect of three repetitions of acute exercise on arylesterase (ARE) activity of the paraoxonase 1 (PON1) enzyme. Eleven average-trained men (age 34.0 ± 5.2 years) completed three treadmill runs. ARE activity in plasma was evaluated spectrophotometrically and compared with PON1 concentration (PON1c), paraoxonase (PON) activity, and high-density lipoprotein cholesterol (HDL-C) at rest and after exercise. In all repetitions of the exercise, ARE activity remained stable, and ARE activity standardized for PON1c (ARE/PON1c) was lower post- than pre-exercise. The ARE/PON1c ratio changes returned to baseline levels during rest after each exercise session. Pre-exercise ARE activity correlated negatively with post-exercise C-reactive protein (CRP) (ρ = -0.35, p = 0.049), white blood cell count (WBC) (ρ = -0.35, p = 0.048), polymorphonuclear leukocytes (PMN) (ρ = -0.37, p = 0.037), and creatine kinase (CK) (ρ = -0.37, p = 0.036). ARE activity may be depleted under conditions of oxidative stress, as increases in PON1c during acute exercise did not result in parallel increases in ARE activity. No adaptation of the response of ARE activity to exercise was detected in subsequent exercise sessions. Individuals with lower pre-exercise ARE activity may develop a higher inflammatory response to strenuous exercise.

Antioxidant Defense Enzymes in Multiple Sclerosis: A 5-Year Follow-up Study.

Oxidative stress biomarkers are increased in multiple sclerosis (MS) lesions. Antioxidant defense enzymes regulate reactive oxygen species that can cause tissue injury in MS. The study of 91 subjects included 64 relapsing-remitting MS (RR-MS, 72% female, baseline age 44.6±SD 11 years; disease duration: 13.3±8.8 years; median EDSS 2.0, IQR: 1.8) and 27 healthy controls (HC) subjects at baseline and 5-year follow-up (5YFU). Serum glutathione peroxidase (GPX), glutathione S-transferase (GST), glutathione reductase (GSHR), superoxide dismutase (SOD), and paraoxonase-1 (PON1) arylesterase and paraoxonase activities were measured using kinetic enzyme assays. Total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) and an apolipoprotein (Apo) panel with ApoA-I, ApoA-II, ApoB, ApoC-II and ApoE were obtained. Serum neurofilament (sNfL) was used to assess axonal injury. Disability was measured on the Expanded Disability Status Scale (EDSS). GSHR activity was lower in HC compared to RR-MS at baseline and 5YFU. GPX (p=0.008) and PON-1 arylesterase and paraoxonase activities (both p=0.05) increased between baseline and 5YFU in HC but did not increase in RR-MS. At baseline and 5YFU, GPX and GST were associated with TC, LDL-C, and ApoA-II; GSHR was associated with ApoA-II and ApoC-II. Antioxidant enzymes were not associated with sNfL or EDSS in RR-MS. RR-MS patients did not exhibit the changes in antioxidant enzyme activities over 5YFU found in HC; however, the differences were modest. Antioxidant enzyme activities are not associated with disability.

Lower paraoxonase 1 paraoxonase activity is associated with a worse prognosis in patients with non-ST-segment elevation myocardial infarction in long-term follow-up.

Acute coronary syndrome (ACS) is one of the main manifestations of coronary artery disease, with a higher prevalence and worst prognosis. Oxidative stress is important in atherosclerosis and ACS, and paraoxonase 1 (PON1) is directly related to reducing the effects of oxidative stress on lipoproteins. The present study evaluated the prognostic value of PON1 activity in patients with non-ST-segment elevation ACS [non-ST-segment elevation myocardial infarction (NSTEMI) and unstable angina (UA)], included in the ERICO study. PON1 paraoxonase activity was determined in serum samples from 485 patients collected on admission. The prognostic value in the follow-up of up to 5 years was evaluated according to cutoff points established by tertiles. Kaplan-Meier curves and Cox regression were used for the analysis of all-cause mortality and cardiovascular mortality. The sample consisted mainly of elderly patients with a high frequency of cardiovascular risk factors. At follow-up of up to 5 years, there were 126 deaths from all causes (80 deaths from CVD). The lowest tertile of PON1 paraoxonase activity was associated with a higher risk of death in patients with NSTEMI, but not in patients with UA. PON1 paraoxonase activity has potential prognostic value in patients with NSTEMI.

Abnormal paraoxonase-1 (PON1) enzyme activity in idiopathic inflammatory myopathies.

Patients with idiopathic inflammatory myopathies (IIM) have severe vascular involvement, which contributes to disease morbidity and mortality. Paraoxonase-1 (PON1) is a high-density lipoprotein (HDL) associated protein that protects the vascular endothelium from oxidative injury and damage. The current work assessed the functional and genetic determinants of PON1 activity in IIM patients. A total of 184 IIM patients and 112 healthy controls (HC) were included. PON1 enzyme activity was assessed by paraoxonase, arylesterase and lactonase assays, and the Q192R PON1 single nucleotide polymorphism (SNP) was analysed. Multivariate regression models examined associations of PON1 activity with IIM diagnosis and myositis disease outcomes. The arylesterase and lactonase activities of PON1 were significantly lower in IIM patients compared with HC. Higher myositis disease activity, the presence of severe IIM-associated interstitial lung disease (ILD), and the presence of MDA5 or anti-synthetase antibodies were significantly associated with lower PON1 activity. The PON1 Q192R polymorphism was strongly linked to the paraoxonase activity of PON1 in IIM, and patients with the PON1 QQ genotype had better IIM disease outcomes compared with patients with the QR or RR genotypes. The arylesterase and lactonase activities of PON1 are significantly impaired in IIM patients compared with HC, and inversely associate with IIM disease activity and the presence of severe ILD. The PON1 QQ genotype associates with more favourable disease outcomes in IIM patients. Large prospective studies are needed to further evaluate the role of PON1 and PON1 genetic polymorphisms in the development and propagation of IIM and IIM-ILD.

Paraoxonase 1 concerning dyslipidaemia, cardiovascular diseases, and mortality in haemodialysis patients

Paraoxonase 1 (PON1) is known for preventing atherosclerosis through lipid-modifying features, antioxidant activity, anti-inflammatory, anti-apoptosis, anti-thrombosis, and anti-adhesion properties. Uremic patients requiring haemodialysis (HD) are especially prone to atherosclerosis and its complications. We analysed the PON1 gene (PON1) polymorphisms and serum PON1 (paraoxonase) activity concerning dyslipidaemia and related cardiovascular diseases and mortality to show how they associate under uremic conditions modified by maintenance HD treatment. The rs662 AA + AG (OR 1.76, 95%CI 1.10–2.80, P = 0.018), rs854560 TT (OR 1.48, 95%CI 1.04–2.11, P = 0.031), and rs854560 AT + TT (OR 1.28, 95%CI 1.01–1.63, P = 0.040) contributed to the prevalence of atherogenic dyslipidaemia diagnosed by the triglyceride (TG)/HDL-cholesterol ratio ≥ 3.8. The normalized serum PON1 activity positively correlated with atherogenic dyslipidaemia (ẞ 0.67 ± 0.25, P = 0.008). The PON1 rs854560 allele T was involved in the higher prevalence of ischemic cerebral stroke (OR 1.38, 1.02–1.85, P = 0.034). The PON1 rs705379 TT genotype contributed to cardiovascular (HR 1.27, 95% CI 1.03–1.57, P = 0.025) and cardiac (HR 1.34, 95% CI 1.05–1.71, P = 0.018) mortality. All P-values were obtained in multiple regression analyses, including clinical variables. Multifaceted associations of PON1 with dyslipidaemia, ischemic cerebral stroke, and cardiovascular mortality in HD patients provide arguments for the consideration of PON1 and its protein product as therapeutic targets in the prevention of atherosclerosis and its complications in uremic patients.

A Multi-Omics Analysis of PON1 Lactonase Activity in Relation to Human Health and Disease.

Paraoxonase 1 (PON1) enzyme has antioxidative properties and is present in mammalian blood and several other body fluids. In blood, PON1 is usually integrated into the high-density lipoprotein (HDL) cholesterol. PON1 is a highly versatile enzyme displaying diverse functions such as arylesterase, lactonase, and paraoxonase, among others. PON1 activities are usually investigated with artificial substrates, for example, dihydrocoumarin and thiobutyl butyrolactone for lactonase activity. The PON1 enzyme activities measured with different substrates tend to be falsely assumed as being equivalent in the literature, although there are poor or weak correlations among the PON1 enzyme activities with different substrates. In addition, and despite our knowledge of the factors influencing PON1 paraoxonase and arylesterase activities, there is little knowledge of PON1 lactonase activity variations and attendant mechanisms. This is important considering further that the lactonase activity is the native activity of PON1. We report here a multi-omics analysis of PON1 lactonase activity. The influence of genetic variations, particularly of single nucleotide polymorphisms and epigenetic, proteomic, and lipidomic variations on PON1 lactonase activity are reviewed. In addition, the influence of various environmental, clinical, and demographic variables on PON1 lactonase activity is discussed. Finally, we examine the associations between PON1 lactonase activity and health states and common complex diseases such as atherosclerosis, dementias, obesity, and diabetes. To the best of our knowledge, this is the first multi-omics analysis of PON1 lactonase activity with an eye to future applications in basic life sciences and translational medicine and the nuances of critically interpreting PON1 function with lactones as substrates.

Kiwifruit Supplementation Increases the Activity of the Paraoxonase Enzyme and decreases Oxidized Low-Density Lipoprotein in High-Fat Diet Fed Hamsters

Background: It is shown that kiwifruit elevates serum high-density lipoprotein cholesterol (HDL-C) levels and exhibits beneficial effects on human health due to its antioxidant potential. Objectives: This study aimed to investigate the impact of kiwifruit on the activity of the paraoxonase 1 (PON1) enzyme, as a main antioxidant enzyme in HDL functionality, in a high-fat diet (HFD). Methods: To this end, 42 male Syrian hamsters were divided into 6 groups including hamsters receiving a normal diet (the control normal group), a regular diet supplemented with kiwifruit at two concentrations (i.e., 1.86 g/kg and 3.73 g/kg), a HFD comprised of 15% butterfat + 0.05% cholesterol (the control high-fat group), and a HFD supplemented with kiwifruit at two concentrations (i.e., 1.86 and 3.73 g/kg) for 8 weeks. Results: The results showed that supplementation of kiwifruit to the HFD increased the levels of HDL-C and remarkably reduced the concentrations of oxidized low-density lipoprotein (ox-LDL) and malondialdehyde (MDA) compared with the control-HF group. In addition, the paraoxonase activity of PON1 significantly increased in HFD supplemented with kiwifruit (1.86 g/kg), and finally, arylesterase (ARE) activity increased in all treated groups when compared with untreated groups. Conclusion: Our findings suggested that kiwifruit can improve the lipid profile and prevent oxidative stress-induced by lipid peroxidation in hamsters receiving HFD, thus increasing the ARE and paraoxonase activities of PON1.

Paraoxonase 1 Activity, Polymorphism and Atherosclerosis Risk Factors in Patients Undergoing Coronary Artery Surgery.

Background: Paraoxonase1 (PON1), an enzyme connected to high density lipoproteins (HDL) particles, plays an important role in protecting arteries against atherosclerosis. The serum activity and concentration of PON1 depends on several genetic polymorphisms as well as environmental factors. Materials and methods: Investigated population consisted of 71 patients aged 43–76 years with confirmed coronary heart disease (CHD). Established risk factors of CHD such as hypertension, elevated total cholesterol and LDL cholesterol (LDL-C), low HDL cholesterol (HDL-C), diabetes mellitus, obesity, smoking and premature CHD in family history were assessed. PON1 genotype for −108C/T promotor region was determined by polymerase chain reaction-restriction fragments length polymorphism (PCR–RFLP) method. Paraoxonase activity towards paraoxon and arylesterase activity towards phenyl acetate were measured spectrophotometrically. Results: Significant correlations between diabetes mellitus and paraoxonase activity (R = −0.264, p = 0.026) and between the premature coronary heart disease in family history and PON1 activity (R = −0.293, p = 0.013) were found. In multivariate analysis, PON1 paraoxonase activity was independently of confounding factors associated with diabetes (OR = 0.985; p = 0.024) and premature CHD in family history (OR = 0.983; p = 0.027). PON1 activity towards aryl acetate positively correlated with HDL-C level (R = 0.255, p = 0.032). In patients treated with statins, PON1 paraoxonase activity was significantly (p = 0.033) higher than in patients without treatment. Conclusions: In diabetic patients with CHD, paraoxonase activity is lower than in normoglycemic patients despite similar lipid profiles. Diabetes and positive family history in patients with overt CHD are associated with the serum PON1 activity, which might be an additional factor helpful in evaluating cardiovascular risk in this group of patients.

Changes in lecithin: cholesterol acyltransferase, cholesteryl ester transfer protein and paraoxonase-1 activities in patients with colorectal cancer

BackgroundPrevious studies revealed decreased level of high-density lipoprotein cholesterol (HDLC) as important factor for development of colorectal cancer (CRC). Quantity and structure of HDL particles depend on activities of lipid transfer proteins lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP), but this topic is largely unexplored in CRC. The main objective of this study was to investigate activities of LCAT and CETP in patients with CRC. Additionally, we analyzed activity of paraoxonase-1 (PON-1), as a main carrier of HDL-antioxidant function. Materials and methodsNinety-nine CRC patients and 101 healthy individuals were included. LCAT and CETP activities were assessed by measuring rates of formation and transfer of cholesteryl esters. PON-1 paraoxonase and arylesterase activities were measured. ResultsLower levels of HDL-C (p < .001) were observed in cohort of patients, alongside with decreased LCAT (p < .050) and increased CETP activity (p < .050). Both PON-1 activities were diminished in CRC (p < .050 and p < .001 respectively). Univariate logistic regression singled out HDL-C level (OR = 0.218, p < .001), CETP activity (OR = 1.010, p < .01) and mass (OR = 0.994, p < .001) as possible markers of elevated CRC risk. CETP mass maintained its predictive significance when adjusted for traditional risk factors and level of oxidative stress (OR = 0.993, p < .001; OR = 0.982, p < .050, respectively). ConclusionOur results demonstrated increased CETP and decreased LCAT and PON-1 activities in CRC patients. In preliminary analysis CETP mass was identified as potential significant predictor of CRC development, suggesting that alterations in HDL-C levels, alongside with changes in HDL structure might have a role in carcinogenesis.

Paraoxonase-1 polymorphisms and cerebral ischemic stroke: a pilot study in mexican patients

Background: The serum paraoxonase-1 (PON1) associated to HDL presents two common polymorphisms in the positions 192 and 55. These polymorphisms are considered determinant of the capacity of HDL to protect LDL from their oxidative modification. In this context, the PON1 genotype has been associated with cardiovascular diseases, including stroke. Objective: To determine the allelic and genotypic frequencies of PON1 L55M and Q192R as well as the enzymatic activities of PON1 in subjects with and without atherothrombotic stroke. Methods: There were included 28 people with atherothrombotic stroke and 29 without stroke. The genotyping was carried out by PCR-RFLP and the phenotyping by measurement of the activities of paraoxonase and arylesterase in serum. Results: For the polymorphism Q192R, the allelic frequencies (Q/R) were 0.46/0.54 and 0.48/0.52 (p= 0.843) for the control group and the group with stroke, respectively. While for the polymorphism L55M, the allelic frequencies (L/M) were 0.81/0.19 for the control group, and 0.78/0.22 for the group with stroke (p= 0.610). The activity levels of paraoxonase were not significantly different between the control and stroke groups (450 vs. 348 UI/mL, p= 0.093) While the activity levels of arylesterase were significantly different between the studied groups (90 vs. 70 UI/mL, p= 0.001); however, upon adjustment by multiple linear regression, it was not longer significant. Conclusion: The polymorphisms Q192R and L55M, and the paraoxonase activity of PON1 are not risk factors for atherothrombotic stroke according to the results of this study.

Paraoxonase-1 polymorphisms and cerebral ischemic stroke: a pilot study in mexican patients.

Background: The serum paraoxonase-1 (PON1) associated to HDL presents two common polymorphisms in the positions 192 and 55. These polymorphisms are considered determinant of the capacity of HDL to protect LDL from their oxidative modification. In this context, the PON1 genotype has been associated with cardiovascular diseases, including stroke.Objective: To determine the allelic and genotypic frequencies of PON1 L55M and Q192R as well as the enzymatic activities of PON1 in subjects with and without atherothrombotic stroke.Methods: There were included 28 people with atherothrombotic stroke and 29 without stroke. The genotyping was carried out by PCR-RFLP and the phenotyping by measurement of the activities of paraoxonase and arylesterase in serum.Results: For the polymorphism Q192R, the allelic frequencies (Q/R) were 0.46/0.54 and 0.48/0.52 (p= 0.843) for the control group and the group with stroke, respectively. While for the polymorphism L55M, the allelic frequencies (L/M) were 0.81/0.19 for the control group, and 0.78/0.22 for the group with stroke (p= 0.610). The activity levels of paraoxonase were not significantly different between the control and stroke groups (450 vs. 348 UI/mL, p= 0.093) While the activity levels of arylesterase were significantly different between the studied groups (90 vs. 70 UI/mL, p= 0.001); however, upon adjustment by multiple linear regression, it was not longer significant.Conclusion: The polymorphisms Q192R and L55M, and the paraoxonase activity of PON1 are not risk factors for atherothrombotic stroke according to the results of this study.

Activity of paraoxonase 1 (PON1) on HDL2 and HDL3 subclasses in renal disease

IntroductionCardiovascular complications, as the main cause of mortality in renal patients, are followed with altered lipoproteins composition. Considering that paraoxonase-1 (PON1) is an anti-oxidative enzyme located mainly on HDL particles, the current study has aim to investigate whether failure of kidney function leads to changes in the distribution of PON1 activity between different HDL subclasses. Materials and methodsIn 77 renal patients (21 chronic kidney disease (CKD) and 56 end stage renal disease (ESRD) patients on dialysis) and 20 healthy subjects PON1 activity on HDL2 and HDL3 subclasses was determined by zymogram method that combines gradient gel electrophoresis separation of HDL subclasses and measurement of PON1 activity in the same gel. ResultsSerum paraoxonase (p<0.01) and arylesterase activity (p<0.001) of PON1 as well as its concentration (p<0.01) were significantly lower in CKD and ESRD patients compared to controls. Relative proportion of HDL3 subclasses was higher in ESRD patients than in healthy participants, while HDL2 subclasses was significantly decreased in CKD (p<0.05) and ESRD (p<0.001) patients, as compared to controls. Furthermore, control subjects had higher PON1 activity on HDL2 (CKD and ESRD patients p<0.001) and HDL3 (CKD p<0.05; ESRD patients p<0.001) subclasses in comparison with the both patients groups. Also, significant negative correlation was found between paraoxonase activity of PON1 in serum and creatinine concentration (ρ=‐0.373, p<0.01). ConclusionsThis study showed that altered HDL subclasses distribution, changed PON1 activities on different HDL subclasses as well as diminished anti-oxidative protection could be important factors in atherosclerosis development in CKD and ESRD patients.

Plasminogen Activator Inhibitor-1 Level Correlates with Lipoprotein Subfractions in Obese Nondiabetic Subjects.

Background The elevated level of plasminogen activator inhibitor-1 (PAI-1) in obese subjects with metabolic syndrome and in patients with type 2 diabetes is well established. The association of plasma PAI-1 and lipid metabolism is still unclear. The aim of the present study was to determine the relationship between plasma PAI-1 levels and the distribution of lipoprotein subfractions in obese and lean nondiabetic individuals. Subjects and Methods We enrolled fifty nondiabetic obese patients and thirty-two healthy volunteers. Lipoprotein subfractions were detected with Lipoprint System. Plasma PAI-1, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and myeloperoxidase (MPO) concentrations were determined with enzyme-linked immunosorbent assay (ELISA), while serum paraoxonase-1 (PON1) activities were measured by spectrophotometry. Results The TNF-α, IL-6, oxidized low-density lipoprotein (oxLDL), and MPO levels were found to be significantly higher, while PON1 paraoxonase and arylesterase activities were nonsignificantly lower in the obese patients. Strong significant negative correlations were found between plasma PAI-1 concentration and mean LDL size, as well as between PAI-1 concentrations and the levels of the large and intermediate high-density lipoprotein (HDL) subfractions. In multiple regression analysis, PAI-1 was predicted by waist circumference and intermediate HDL subfraction. Conclusion The significant correlations between PAI-1 levels and lipoprotein subfractions indicate the link between PAI-1 and lipid metabolism in obesity.

Paraoxonase 1 Q192R genotype and activity affect homocysteine thiolactone levels in humans.

Genetic or nutritional deficiencies in 1 carbon and homocysteine (Hcy) metabolism elevate Hcy-thiolactone levels and are associated with cardiovascular and neurologic diseases. Hcy-thiolactone causes protein damage, cellular toxicity, and proatherogenic changes in gene expression in human cells and tissues. A polymorphic cardio-protective enzyme, paraoxonase 1 (PON1), hydrolyzes Hcy-thiolactone in vitro. However, whether Hcy-thiolactone hydrolysis is a physiologic function of the PON1 protein and whether polymorphisms in the PON1 gene affect Hcy-thiolactone levels in humans was unknown. Here we show that the PON1-192 genotype, which affects the enzymatic activity of the PON1 protein, also affected urinary Hcy-thiolactone levels, normalized to creatinine. Carriers of the PON1-192R allele had significantly lower Hcy-thiolactone/creatinine levels than individuals carrying the PON1-192Q allele. Individuals with low serum PON1 paraoxonase activity had significantly higher Hcy-thiolactone/creatinine levels compared with individuals with high paraoxonase activity. In contrast, Hcy-thiolactone/creatinine levels were unaffected by serum PON1 arylesterase activity or by PON1 protein levels. Taken together, these findings suggest that PON1 hydrolyzes Hcy-thiolactone in humans and that the interindividual variations in PON1 genotype/activity can modulate the pathology of hyperhomocysteinemia.-Perła-Kaján, J., Borowczyk, K., Głowacki, R., Nygård, O., Jakubowski, H. Paraoxonase 1 Q192r genotype and activity affect homocysteine thiolactone levels in humans.

Abstract 176: Preoperative Small HDL Particle Concentration is Associated with Paraoxonase-1 activity and the Risk of Acute Kidney Injury After Cardiac Surgery

Acute kidney injury (AKI) after cardiac surgery occurs in up to 30% of patients and predicts death. We have reported that a higher preoperative HDL particle concentration is independently associated with a decreased risk of AKI after cardiac surgery. HDL has known anti-oxidant properties that may attenuate AKI. We hypothesized that HDL particle size is associated with paraoxonase-1 (PON-1) activity and with the risk of AKI after cardiac surgery. We selected 90 patients who developed mild, moderate, severe, or no AKI from a prospective trial of perioperative atorvastatin to prevent post-cardiac surgery AKI. PON-1 paraoxonase activity was measured in apoB-depleted serum with fluorescent substrate 7-diethylphospho-6,8-dixuor-4-methylumbelliferyl. HDL particle size was assessed using the NMR Lipoprofile test. Linear regression was used to assess the association between preoperative small, medium, and large HDL particle concentrations and PON-1 activity. We assessed the association between HDL particle levels and the maximum serum creatinine change from baseline in the first 48 postoperative hours using two-component latent variable mixture models adjusted for AKI risk factors. A higher preoperative small HDL particle concentration was associated with a higher preoperative PON-1 activity (p=0.003, Figure 1A). Medium and large HDL particle concentrations were not associated with PON-1 activity. Small HDL particle concentration was found to be independently associated with postoperative serum creatinine change (p=0.02, Figure 1B), while medium and large HDL particle concentrations were not. Conclusions: A higher preoperative small HDL particle concentration was associated with a higher PON-1 activity and a decreased risk of AKI after cardiac surgery. Future work will characterize HDL throughout the surgical course to identify the mechanism underlying the protective association between HDL and AKI.

Serum concentrations of trace elements and their relationships with paraoxonase-1 in morbidly obese women

The metabolic alterations associated with obesity include mineral dysregulation. Essential trace elements are nutrients with a relevant function in a large number of cellular processes and multiple roles in the correct functioning of metabolic enzymes. Paraoxonase-1 (PON1) is an antioxidant and anti-inflammatory enzyme that is compromised in obesity. In the present study, the potential alterations in trace elements in morbidly obese women were assessed in relation to serum PON1 activity and concentration, as well as to other obesity-related comorbidities such as diabetes mellitus and fatty liver. We recruited 41 morbidly obese women and 51 control individuals. The serum concentrations of 30 elements, PON1 paraoxonase and lactonase activities, and PON1 concentration were measured. We observed significant alterations in the levels of As, Ba, Cu, Ca, Fe, Mg, Na, Se, Sr, and Zn in obese women; some of them (As, Ca, Cr, Cu, Mg, and Se) being significantly correlated with serum PON1 values. The most relevant changes were observed in the concentrations of As, Sr and Mg, the last of which was also significantly associated with diabetes mellitus. The current results raise the possibility that increased ingestion and/or storage of a number of trace elements may be factors predisposing to obesity-related comorbidities and metabolic alterations.

Serum paraoxonase 1 activity and lipid metabolism parameter changes in Dachshunds with chronic mitral valve disease. Assessment of its diagnostic usefulness.

Chronic mitral valve disease, which is frequently diagnosed in Dachshunds, leads to structural, hemodynamic and redox state changes in dogs. The aim of this study was to investigate serum paraoxonase 1 (PON1) activity and lipid metabolism in different disease stages. Standardized PON1 activity (PON1/HDL ratio) was lower in asymptomatic dogs, B1 and B2 Stages when compared to healthy ones and symptomatic Dachshunds in Stage C (ACVIM classfication). PON1 paraoxonase activity was elevated in Stage C dogs, with no changes found in PON1 activity towards phenyl acetate. Dachshunds in Stage B2 and C showed increased triglyceride levels, with no changes in cholesterol and lipoprotein concentration in comparison to healthy ones. Our data suggest that standardized PON1 activity changes could be used in laboratory diagnostics to differentiate the CMVD of affected asymptomatic (Stage B1 and B2) dogs from healthy (Stage A) and clinically affected (Stage C) dogs. Also, a standardized PON1 activity increase might be a prognostic progression signal of the disease to Stage C.

Similar Active Sites and Mechanisms Do Not Lead to Cross-Promiscuity in Organophosphate Hydrolysis: Implications for Biotherapeutic Engineering.

Organophosphate hydrolases are proficient catalysts of the breakdown of neurotoxic organophosphates and have great potential as both biotherapeutics for treating acute organophosphate toxicity and as bioremediation agents. However, proficient organophosphatases such as serum paraoxonase 1 (PON1) and the organophosphate-hydrolyzing lactonase SsoPox are unable to hydrolyze bulkyorganophosphates with challenging leaving groups such as diisopropyl fluorophosphate (DFP) or venomous agent X, creating a major challenge for enzyme design. Curiously, despite their mutually exclusive substrate specificities, PON1 and diisopropyl fluorophosphatase (DFPase) have essentially identical active sites and tertiary structures. In the present work, we use empirical valence bond simulations to probe the catalytic mechanism of DFPase as well as temperature, pH, and mutational effects, demonstrating that DFPase and PON1 also likely utilize identical catalytic mechanisms to hydrolyze their respective substrates. However, detailed examination of both static structures and dynamical simulations demonstrates subtle but significant differences in the electrostatic properties and solvent penetration of the two active sites and, most critically, the role of residues that make no direct contact with either substrate in acting as “specificity switches” between the two enzymes. Specifically, we demonstrate that key residues that are structurally and functionally critical for the paraoxonase activity of PON1 prevent it from being able to hydrolyze DFP with its fluoride leaving group. These insights expand our understanding of the drivers of the evolution of divergent substrate specificity in enzymes with identical active sites and guide the future design of organophosphate hydrolases that hydrolyze compounds with challenging leaving groups.

Plasma Metabolome, PON1 Status, Environmental Exposures and Childhood Autism

BackgroundFew studies have examined Autism Spectrum Disorder (ASD) and the interplay between genetics and environmental factors. The paraoxonase 1 (PON1) gene regulates the breakdown of organophosphate (OP) pesticides in the body and serves as an important antioxidant. PON1 levels may be affected by single nucleotide polymorphisms (SNPs), therefore individuals with certain PON1 SNPs plus environmental exposure during pregnancy may be at an increased risk for having a child with autism.ObjectiveThe objective of this study was to examine a possible gene‐environment interaction that focuses on prenatal environmental exposures and child metabolic vulnerability as a consequence of polymorphisms in the PON1 gene.MethodsAll children (n=400) in the present study including children with Autism Spectrum Disorder (ASD; n=200), and typically developed control children (TD; n=200) are part of a large ongoing population based case‐control CHARGE (CHildhood Autism Risk from Genetics and Environment) Study. Blood plasma metabolome profiles were obtained by Nuclear Magnetic Resonance (NMR) spectroscopy. Untargeted metabolomics analysis using Chemomx NMR Suite 8.1 was used to identify and quantify 69 metabolites in each sample including amino acids, organic acids, sugars and other compounds. The concentration of PON1 was determined by ELISA kits (Cloud‐Clone Corp), and paraoxonase activity was measured using commercially available assay kits (Molecular Probes Inc.). SNP data and environmental exposure data were previously collected in the CHARGE Study.ResultsChildren with ASD had higher levels of lactate, a metabolic waste product, and higher levels of the amino acids: alanine, serine, glycine, and tryptophan, consistent with mitochondrial dysfunction, and altered energy metabolism. In addition, ASD was associated with higher levels of uridine, a component of RNA previously reported to be inversely correlated with methylation capacity. Although we did not find a significant difference in the PON1 concentration and paraoxonase activity of children with ASD compared to controls, we did find that PON1 SNPs in coding and non‐coding regions significantly affected its plasma concentrations. Moreover, there were a disproportionate number of children with ASD and specific PON1 SNPs that correlated with maternal organophosphate exposures.ConclusionOur results add to the growing body of literature indicating autism is associated with an altered metabolic state compared to typically developed controls. These results suggest that maternal environmental exposures during pregnancy in combination with genetics may impact a child's metabolic outcome. Further studies are needed to understand how the metabolome affects neurodevelopmental outcome, or conversely if neurodevelopmental outcome affects the metabolome.Support or Funding InformationThis study was funded by the NIH 1P30 ESO23513‐01A1 pilot grant, the Administrative Supplement to the CHARGE Study R01 ES015359, and the USDA National Institute of Food and Agriculture Hatch Project 1005945.

A preliminary study of paraoxonase-1 in infected patients with an indwelling central venous catheter

ObjectivesIdentification of biochemical markers to diagnose bloodstream infections in patients with a central venous catheter (CVC) inserted is an active research pursuit. Paraoxonase-1 (PON1) is an enzyme participating in the innate immune system protecting against toxic substances and infectious agents. We investigated the relationships between serum PON1 alterations and the characteristics of infection in a group of patients with a CVC implant. MethodsPatients (n=114) who had had an inserted CVC removed because of infection or because the usefulness was at an end, and 407 healthy volunteers were recruited. In all participants we measured serum PON1 lactonase and paraoxonase activities, PON1 concentration and genetic polymorphisms, together with levels of the chemokine (C–C motif) ligand 2 (CCL2), procalcitonin and C-reactive protein (CRP). ResultsPatients with an acute concomitant infection (ACI) had higher CCL2, CRP and procalcitonin concentrations than the control group, together with lower paraoxonase and lactonase activities and specific activities. The areas under the curve of the receiver operating characteristic plots for paraoxonase and lactonase specific activities in the discrimination between patients with or without and ACI were 0.81 (0.73–0.89) and 0.81 (0.71–0.89), respectively, indicating the high diagnostic accuracy of these parameters. ConclusionThis preliminary study suggests that the measurement of PON1 may be useful as a tool for the diagnosis of ACI in patients with an indwelling CVC.