Analysis of paraoxonase 1 (PON1) genetic polymorphisms and activities as risk factors for ischemic stroke in Turkish population

Paraoxonase 1 status is a major Janus-faced component of mild and moderate acute ischemic stroke and consequent disabilities

AIMS

This study aims to examine the associations between paraoxonase 1 (PON)1 status and acute ischemic stroke (AIS) and consequent disabilities.

METHODS

This study recruited 122 patients with AIS and 40 healthy controls and assessed the Q192R gene variants, arylesterase (AREase) and chloromethyl phenylacetate (CMPAase) activities, and high-density lipoprotein cholesterol (HDLc) in baseline conditions. AREase and CMPAase were measured 3 months later. The National Institutes of Health Stroke Scale (NIHSS) and the modified Rankin score (mRS) were assessed at baseline and 3 and 6 months later.

RESULTS

Reduced CMPAase and increased AREase activities are significantly associated with AIS and mRS and NIHSS scores (baseline and 3 and 6 months later). The best predictor of AIS/disabilities was a decrease in the z-unit-based composite zCMPAase-zAREase score. Serum high density lipoprotein cholsterol (HDLc) was significantly correlated with CMPAase, but not AREase, activity and a lowered zCMPAase + zHDLc score was the second best predictor of AIS/disabilities. Regression analysis showed that 34.7% of the variance in baseline NIHSS was explained by zCMPAase-zAREase and zCMPAase + zHDLc composites, HDLc, and hypertension. Neural network analysis showed that stroke was differentiated from controls with an area under the ROC curve of 0.975 using both new composite scores, PON1 status, hypertension, dyslipidemia, previous stroke as body mass index. The PON1 Q192R genotype has many significant direct and mediated effects on AIS/disabilities, however, its overall effect was not significant.

DISCUSSION

PON1 status and the CMPAase-HDLc complex play key roles in AIS and its disabilities at baseline and 3 and 6 months later.

Proteomics-Based Approach to Identify Novel Blood Biomarker Candidates for Differentiating Intracerebral Hemorrhage From Ischemic Stroke-A Pilot Study

Background: A reliable distinction between ischemic stroke (IS) and intracerebral hemorrhage (ICH) is required for diagnosis-specific treatment and effective secondary prevention in patients with stroke. However, in resource-limited settings brain imaging, which is the current diagnostic gold standard for this purpose, is not always available in time. Hence, an easily accessible and broadly applicable blood biomarker-based diagnostic test differing stroke subtypes would be desirable. Using an explorative proteomics approach, this pilot study aimed to identify novel blood biomarker candidates for distinguishing IS from ICH.

Material and Methods: Plasma samples from patients with IS and ICH were drawn during hospitalization and were analyzed by using liquid chromatography/mass spectrometry. Proteins were identified using the human reference proteome database UniProtKB, and label-free quantification (LFQ) data were further analyzed using bioinformatic tools.

Results: Plasma specimens of three patients with IS and four patients with ICH with a median National Institute of Health Stroke Scale (NIHSS) of 12 [interquartile range (IQR) 10.5–18.5] as well as serum samples from two healthy volunteers were analyzed. Among 495 identified protein groups, a total of 368 protein groups exhibited enough data points to be entered into quantitative analysis. Of the remaining 22 top-listed proteins, a significant difference between IS and ICH was found for Carboxypeptidase N subunit 2 (CPN2), Coagulation factor XII (FXII), Plasminogen, Mannan-binding lectin serine protease 1, Serum amyloid P-component, Paraoxonase 1, Carbonic anhydrase 1, Fibulin-1, and Granulins.

Discussion: In this exploratory proteomics-based pilot study, nine candidate biomarkers for differentiation of IS and ICH were identified. The proteins belong to the immune system, the coagulation cascade, and the apoptosis system, respectively. Further investigations in larger cohorts of patients with stroke using additional biochemical analysis methods, such as ELISA or Western Blotting are now necessary to validate these markers, and to characterize diagnostic accuracy with regard to the development of a point-of-care-system for use in resource-limited areas.

PON1 (Paraoxonase 1) Q192R gene polymorphism in ischemic stroke among North Indian population

Background:

PON1 is an High Density Lipoprotein (HDL)-associated esterase. Two common polymorphisms in the PON1 gene, Q192R and L55M substitutions, determine the inter-individual variation in PON1 activity. The association of these polymorphisms with the risk of ischemic stroke remains controversial. In the present study, the role of PON1 Q192R gene polymorphism in ischemic stroke was studied in the Indian population.

Design and Methods:

In the present case-control study, the PON1 Q192R gene polymorphism was screened in ischemic stroke patients (n: 63) and age, sex-matched controls (n: 63) using thePolymerase Chain Reaction-Restriction Segment Length Polymorphism (PCR-RFLP) method.

Results:

The mean age of stroke presentation was 58.11 ± 15.4 years. A total of 17.4% cases presented with young stroke (<45 years age) and 9.52% cases were seen to have a recurrent stroke. The distribution of -192Q/R PON1 gene polymorphism was not seen to differ between cases and controls. The traditional stroke risk factors did not have any effect on the PON1 genotype expression. A multivariate logistic regression analysis was done in order to assess an independent association of age, gender, traditional stroke risk factors, and PON1 polymorphism with acute ischemic stroke. However, neither the RR genotype nor the presence of the R allele was associated with an increase in the risk of acute ischemic stroke (OR [RR genotype]-4.76, P value: 0.24, 95% CI: 0.3497–64.8531; OR [R allele]-0.94, P value: 0.90, 95% CI: 0.3516–2.4989).

Conclusion:

PON1 Q192R gene polymorphism is not associated with an increased risk of acute ischemic stroke in the North Indian population. Further studies with a larger sample size are needed before PON1 Q192R gene polymorphism can be considered as a genetic risk factor for ischemic stroke.

The Relevance of Noncoding DNA Variations of Paraoxonase Gene Cluster in Atherosclerosis-Related Diseases

The human paraoxonase (PON) gene cluster is comprised of three contiguous genes (PON1, PON2 and PON3) of presumably common origin coding three lactonases of highly similar structure and substrate specificity. The catalytic activity of PON proteins is directed toward artificial organophosphates and in physiological conditions toward thiolactones and oxidized phospholipids. Consequently, PON enzymes are regarded as an effective defense against oxidative stress and, as a result, against atherosclerosis development. Additionally, both PON's serum activity and its concentration are influenced by several polymorphic variations in coding and noncoding DNA regions of the PON gene cluster remaining in linkage disequilibrium. Hence, the genetic polymorphism of the PON gene cluster may contribute to atherosclerotic process progression or deceleration. In this review the authors analyzed the relevance of noncoding DNA polymorphic variations of PON genes in atherosclerosis-related diseases involving coronary and peripheral artery disease, stroke, diabetes mellitus, dementia and renal disease and concluded that the effect of PON gene cluster' polymorphism has a considerable impact on the course and outcome in these conditions. The following PON genetic variations may serve as additional predictors of the risk of atherosclerosis in selected populations and individuals.

The Antioxidant Enzyme PON1: A Potential Prognostic Predictor of Acute Ischemic Stroke

Objective

Paraoxonase 1 (PON1) is an antioxidant enzyme, which has been proved to be involved in the pathophysiological process of oxidative stress and various neurological diseases in recent years. Although reduced PON1 activity has been reported in patients with acute ischemic stroke (AIS), the prognostic value of PON1 in AIS has not been clearly established. The purpose of this study was to determine whether the baseline serum PON1 activity level is related to the functional outcome of AIS patients.

Methods

From July 2017 to June 2020, AIS patients within 3 days of symptom onset were continuously prospectively included in the study. On admission, clinical and laboratory data were recorded, and serum PON1 activity was tested. The National Institute of Health Stroke Scale (NIHSS) score was used to evaluate the initial neurologic deficit at admission, and the modified Rankin scale (mRS) was used to evaluate the functional outcome at 3 months. A multiple logistic regression model was used to analyze the relationship between the baseline PON1 activity level and the prognosis of AIS.

Results

A total of 336 AIS patients were finally included in this study. The serum PON1 activity of AIS patients with good outcomes was significantly higher than that of patients with poor outcomes (193.4 ± 16.3 U/mL vs. 127.2 ± 14.9 U/mL, p < 0.001). However, the comparison of other clinical and laboratory data between AIS patients with good and poor outcomes was not significant (p > 0.05). There was a significant decrease in the mRS score in patients with AIS across serum PON1 quartiles (3.0 ± 1.6, 2.6 ± 1.5, 2.4 ± 1.4, and 2.4 ± 1.3, p = 0.007). Multivariate logistic regression analysis showed that the 3-month functional outcome of AIS patients was significantly correlated with the quartile of serum PON1 activity.

Conclusions

This study suggests that the serum PON1 activity may be an independent predictor of the functional outcome of AIS patients.

Shared genetic risk factors for depression and stroke

BACKGROUND

The comorbidity of major depressive disorder (MDD) and stroke are common in clinic. There is a growing body of evidence suggesting a bi-directional relationship between stroke and depression. However, the mechanisms underlying the relationship between MDD and stroke are poorly investigated. Considering that both MDD and stroke can be heritable and are influenced by multiple risk genes, shared genetic risk factors between MDD and stroke may exist.

OBJECTIVE

The objective is to review the existing evidence for common genetic risk factors for both MDD and stroke and to outline the possible pathophysiological mechanisms mediating this association.

METHODS

A systematic review and meta-analysis was performed. Gene association studies regarding stroke and depression were searched in the database PubMed, CNKI, and Chinese Biomedical Literature Database before December 2018. Statistical analysis was performed using the software Revman 5.3.

RESULTS

Genetic polymorphisms of 4 genes, methylenetetrahydrofolate reductase (MTHFR) and apolipoprotein E (ApoE) have been demonstrated to associate with the increased risk for both MDD and stroke, while the association between identified polymorphisms in angiotensin converting enzyme (ACE) and serum paraoxonase (PON1) with depression is still under debate, for the existing studies are insufficient in sample size. These results suggest the possible pathophysiological mechanisms that are common to these two disorders, including immune-inflammatory imbalance, increased oxidative and nitrative stress, dysregulation of lipoprotein and lipid metabolism, and changes of cerebrovascular morphology and function. Other associated genes with few or conflicting results have also been included, and a few studies have investigated the effects of the described polymorphisms on MDD and stroke comorbidity, such as post stroke depression.

CONCLUSION

These findings suggest that shared genetic pathways may contribute to the comorbidity of MDD and stroke. Studies to evaluate the shared genetic variations between MDD and stroke may provide insights into the molecular mechanisms that trigger disease progression.

Association of paraoxonase 1 (PON1) gene polymorphisms and concentration with essential hypertension

Human serum paraoxonase 1 (PON1) is carried by high-density lipoprotein in blood circulation and is shown to be effective in preventing oxidized phospholipids carried by low-density lipoprotein particles, thus it acts as an antioxidant. Polymorphism in this gene has been investigated for many metabolic diseases, but it is not thought to be a genetic risk factor for essential hypertension. The aim of this study was to determine whether there was an association between PON1 gene polymorphisms and concentration with essential hypertension. The study population was comprised of 100 patients with essential hypertension and 100 healthy controls. One promoter region [C(-108)T] and two coding region (Q192R and L55M) polymorphisms in the PON1 gene were genotyped in individuals by using the TaqMan assay. Plasma PON1 concentration in all volunteers was also measured spectrophotometrically by the enzyme-linked immunosorbent assay method. The genotype and allele frequencies of the PON1 C(-108)T polymorphism showed significant differences between the essential hypertensive and control groups (CT vs. CC: p<0.001; T allele vs. C allele: p<0.001). There was no significant difference for the PON1 L55M polymorphism between the groups, while the heterozygote genotype of the PON1 Q192R polymorphism showed significant difference (p = 0.03). The PON1 concentration was also found to be significantly lower in hypertensive patients (p < 0.001). Decline in the level of PON1 gene may be one of the main factors in the development of essential hypertension, and the PON1 C(-108)T polymorphism may have a prognostic value in the patients with essential hypertension.

PON1 polymorphisms are associated with polycystic ovary syndrome susceptibility, related traits, and PON1 activity in Indian women with the syndrome

OBJECTIVE

To investigate the association of paraoxonase 1 (PON1) polymorphisms (L55M and Q192R) with polycystic ovary syndrome (PCOS) susceptibility and its related traits in Indian women.

DESIGN

Case-control study.

SETTING

Academic research institute, infertility, and endocrinology clinics.

PATIENT(S)

Controls (n = 326), women with PCOS (n = 482).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Genotypic and allelic frequency distribution, genotype-phenotype association, different PON1 activities (lactonase, arylesterase, and paraoxonase).

RESULT(S)

The genotypic and allelic frequency distributions of the L55M polymorphism were significantly different between lean controls and lean women with PCOS, and this polymorphism reduced the risk of PCOS development in lean but not in obese Indian women. Furthermore, this polymorphism was significantly associated with decreased 2-hour glucose, apolipoprotein B, free and bioavailable T, and free androgen index concurrent with increased sex hormone-binding globulin (SHBG) and FSH levels only in lean women with PCOS. However, Q192R polymorphism showed comparable genotypic frequency distribution between controls and women with PCOS. PON1 lactonase and arylesterase activities were significantly decreased in women with PCOS compared with controls. PON1 polymorphisms were shown to influence its activities.

CONCLUSION(S)

Our study showed that L55M, but not Q192R, polymorphism is significantly associated with reduced PCOS susceptibility only in lean women and also impacts glucose metabolism, lipid parameters, and hyperandrogenemia in them. Our study therefore suggests the possibility of differential genetic pathophysiology of PCOS between lean and obese women.

Serum prolidase enzyme activity and oxidative stress levels in patients with acute hemorrhagic stroke

BACKGROUND

It has been indicated that oxidative damage contributes to secondary brain injury in both ischemic and hemorrhagic stroke patients. Collagen is a major component of the extracellular matrix, and prolidase plays a role in collagen synthesis. The aim of this study was to evaluate the serum prolidase activity, nitric oxide (NO) levels, total antioxidant capacity (TAC) and total oxidant status (TOS) in patients with acute hemorrhagic stroke.

METHODS

Twenty-five patients with acute hemorrhagic stroke and 25 controls were enrolled. Serum prolidase activity, catalase activity, NO levels, TAC and TOS were measured spectrophotometrically. Oxidative stress index (OSI) was calculated.

RESULTS

Serum TAC levels and catalase activity were significantly lower in acute hemorrhagic stroke patients than controls (both, p < 0.001), while NO levels, TOS levels, OSI values and prolidase activity were significantly higher (all, p < 0.01). When patients with acute hemorrhagic stroke were divided according to gender, no differences were observed between females and males in respect to serum prolidase enzyme activity, NO levels, TAC levels, TOS levels and OSI values (all, p > 0.05).

CONCLUSIONS

Findings from the study suggest an association between increased oxidative stress levels, decreased antioxidant levels and increased prolidase enzyme activity in patients with acute hemorrhagic stroke compared with controls. More studies are needed to elucidate mechanistic pathways on oxidative stress in patients with acute hemorrhagic stroke.

Serum levels of trace elements and heavy metals in patients with acute hemorrhagic stroke

Trace elements are essential components of biological structures, but alternatively, they can be toxic at concentrations beyond those necessary for their biological functions. Changes in the concentration of essential trace elements and heavy metals may affect acute hemorrhagic stroke. The aim of this study was to measure serum levels of essential trace elements [iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), and magnesium (Mg)] and heavy metals [cobalt (Co), cadmium (Cd), and lead (Pb)] in patients with acute hemorrhagic stroke. Twenty-six patients with acute hemorrhagic stroke and 29 healthy controls were enrolled. Atomic absorption spectrophotometry (UNICAM-929) was used to measure serum Fe, Cu, Pb, Cd, Zn, Co, Mn and Mg concentrations. Serum Cd, Pb and Fe levels were significantly higher in patients with acute hemorrhagic stroke than controls (p < 0.001), while serum Cu, Zn, Mg and Mn levels were significantly lower (all p < 0.001). However, there was no significant difference between the groups with respect to serum Co levels (p > 0.05). We first demonstrate increased Cd, Pb, and Fe levels; and decreased Cu, Zn, Mg, and Mn levels in patients with acute hemorrhagic stroke. These findings may have diagnostic and prognostic value for acute hemorrhagic stroke. Further studies are required to elucidate the roles of trace elements and heavy metals in patients with acute hemorrhagic stroke.

Association between paraoxonase gene and stroke in the Han Chinese population

BACKGROUND

The human paraoxonase (PON) gene family has three isoforms: PON1, PON2 and PON3. These genes are implicated as potential risk factors of cerebrovascular disease and can prevent oxidative modification of low-density lipoproteins and atherosclerosis. This study evaluated the association between the genetic variants of all three PON genes and the risks of total stroke, ischemic stroke and hemorrhagic stroke in the Han Chinese population.

METHODS

A total of 1016 subjects were recruited, including 508 healthy controls and 498 patients (328 with ischemic stroke and 170 with hemorrhagic stroke). A total of 11 single nucleotide polymorphisms (SNPs) covering the PON genes were genotyped for statistical analysis. Two of the 11 SNPs (rs662 and rs854560) were contextualized in a meta-analysis of ischemic stroke.

RESULTS

The presence of rs705381 (-162) in the promoter region of PON1 was significantly associated with total stroke (P(adjusted) = 0.0007, OR = 0.57 [95% CI = 0.41-0.79]) and ischemic stroke (P(adjusted) = 0.0017, OR = 0.54 [95% CI = 0.37-0.79]) when analyzed using a dominant model, but was not associated with hemorrhagic stroke. There was also a nominal association between rs854571 (-824) and total stroke. Meta-analysis demonstrated a significant nominal association between rs662 and ischemic stroke, but there was no evidence of an association between rs662 and ischemic stroke risk in a single site association study.

CONCLUSIONS

These findings indicate that polymorphisms of PON1 gene may be a risk factor of stroke.

R-carrying genotypes of serum paraoxonase (PON1) 192 polymorphism and higher activity ratio are related to susceptibility against ischemic stroke

The polymorphic gene of serum paraoxonase (PON1) and its activity involved in atherosclerosis. The purpose of the study was to analyze PON1 192 Q/R polymorphism and the enzyme activities in ischemic stroke. The polymorphism as the most common polymorphism in PON1 gene coding sequence is associated with variation in the enzyme activity and vascular disease. The study included 85 stroke patients and 71 control subjects. PON1 192 polymorphism was genotyped using PCR protocol. Paraoxonase activity (Para) and arylesterase activity (Aryl) were determined spectrophotometrically using paraoxon and phenylacetate as the substrates. The QR and RR genotypes were more frequent in stroke population compared to controls, resulting in a higher frequency of the R allele in patients (0.24 vs 0.18, OR = 1.41). Patients had significantly higher Para/Aryl ratio than that of controls (P = 0.016). In stroke patients, Para/Aryl and Para/HDL ratios increased with this order: QQ < QR < RR. Hypertension significantly increased the risk of ischemic stroke by 15-fold among R-containing people, while this was significantly increased 4-fold for QQ homozygotes. Smoking increased the risk of having ischemic stroke in both QQ homozygote and QR + RR group (OR = 2.84 and OR = 2.33, respectively). In conclusion, these data highlight the importance of PON1 192 R allele and high Para/Aryl ratio in susceptibility to ischemic stroke in the population. The presence of the 192 R allele potentiates the risk of stroke especially in hypertensive people. Decreased Aryl and increased Para/Aryl, Para/HDL and Aryl/HDL ratios may be markers indicated the increased susceptibility to ischemic stroke in the population.

Paraoxonase 1 and homocysteine metabolism

Paraoxonase 1 (PON1), a component of high-density lipoprotein (HDL), is a calcium-dependent multifunctional enzyme that connects metabolisms of lipoproteins and homocysteine (Hcy). Both PON1 and Hcy have been implicated in human diseases, including atherosclerosis and neurodegeneration. The involvement of Hcy in disease could be mediated through its interactions with PON1. Due to its ability to reduce oxidative stress, PON1 contributes to atheroprotective functions of HDL in mice and humans. Although PON1 has the ability to hydrolyze a variety of substrates, only one of them-Hcy-thiolactone-is known to occur naturally. In humans and mice, Hcy-thiolactonase activity of PON1 protects against N-homocysteinylation, which is detrimental to protein structure and function. PON1 also protects against neurotoxicity associated with hyperhomocysteinemia in mouse models. The links between PON1 and Hcy in relation to pathological states such as coronary artery disease, stroke, diabetic mellitus, kidney failure and Alzheimer's disease that emerge from recent studies are the topics of this review.

PON gene polymorphisms and ischaemic stroke: a systematic review and meta analysis

BACKGROUND

Paraoxonase is known to play an important role in the pathophysiology of atherosclerosis. Genetic variants of the paraoxonase gene have been implicated as risk factors for atherosclerotic diseases such as coronary artery disease, but individual genetic association studies examining the relationship between the paraoxonase gene polymorphisms and ischaemic stroke have yielded inconsistent results.

AIM

This study aimed to evaluate the association between the paraoxonase gene variants and ischaemic stroke using systematic review with meta-analysis.

METHODS

Relevant studies were identified by searching English and Chinese databases extensively. Allele and genotype frequencies for each included study were extracted. The odds ratio was calculated using a random-effects or fixed-effects model. A Q statistic was used to evaluate homogeneity, and Egger's test and funnel plot were used to assess publication bias.

RESULTS

A total of 28 studies were included and identified for the current meta-analysis. It was found that the R allele or RR genotype of paraoxonase 1 Q192R polymorphism had an increased risk for ischaemic stroke in the general population (192R allele: odds ratio: 1·21, 95% confidence interval: 1·08-1·35, P = 0·0009 and 192RR genotype: odds ratio: 1·25, 95% confidence interval: 1·06-1·49, P = 0·009 in general population, respectively), but there was no significant association between other genetic variants of paraoxonase gene and ischaemic stroke.

CONCLUSIONS

Existing evidence indicates that the Q192R polymorphism (the R allele and RR genotype) is associated with an increased risk of ischaemic stroke in the general population. Future studies with larger sample sizes will be necessary to confirm the present results.

Two common nonsynonymous paraoxonase 1 (PON1) gene polymorphisms and brain astrocytoma and meningioma

BACKGROUND

Human serum paraoxonase 1 (PON1) plays a major role in the metabolism of several organophosphorus compounds. The enzyme is encoded by the polymorphic gene PON1, located on chromosome 7q21.3. Aiming to identify genetic variations related to the risk of developing brain tumors, we investigated the putative association between common nonsynonymous PON1 polymorphisms and the risk of developing astrocytoma and meningioma.

METHODS

Seventy one consecutive patients with brain tumors (43 with astrocytoma grade II/III and 28 with meningioma) with ages ranging 21 to 76 years, and 220 healthy controls subjects were analyzed for the frequency of the nonsynonymous PON1 genotypes L55M rs854560 and Q192R rs662. All participants were adult Caucasian individuals recruited in the central area of Spain.

RESULTS

The frequencies of the PON1 genotypes and allelic variants of the polymorphisms PON1 L55M and PON1 Q192R did not differ significantly between patients with astrocytoma and meningioma and controls. The minor allele frequencies were as follows: PON1 55L, 0.398, 0.328 and 0.286 for patients with astrocytoma, meningioma and control individuals, respectively; PON1 192R, 0.341, 0.362 and 0.302 for patients with astrocytoma, meningioma and control individuals, respectively. Correction for age, gender, or education, made no difference in odds ratios and the p values remained non-significant. Haplotype association analyses did not identify any significant association with the risk of developing astrocytoma or meningioma.

CONCLUSIONS

Common nonsynonymous PON1 polymorphisms are not related with the risk of developing astrocytoma and meningioma.