Genetic polymorphism of paraoxonase and the risk of coronary heart disease

A prospective study to assess the role of paraoxonase 1 genotype and phenotype on the lipid-lowering and antioxidant activity of statins

Human paraoxonase 1 (PON1) enzyme protects against atherosclerosis by preventing low-density lipoprotein from oxidative modification. Upregulation of PON1 enzymatic activity is suggested to contribute to atheroprotective potential of statins. Glutamine (Q) to arginine (R) at site 192 and leucine (L) to methionine (M) substitution at site 55 polymorphisms influence the PON1 activity. The study assessed the role of PON1 polymorphisms on lipid-lowering and PON1-modulating activity of statins in a Western Indian cohort of patients with dyslipidemia. Lipid profile and PON1 activity were determined at baseline and 3 months after initiation of statin treatment. PON1 genotypes (QQ, QR, RR; LL, LM, and MM) were determined by PCR-RFLP. Paraoxon was used as a substrate for assessing PON1 activity by spectrophotometry. A total of 140 statin-naïve patients were enrolled; of them, 116 were available for final analysis. Fifty-seven (50%) had QQ, 39 (35%) had QR, and 17 (15%) had RR genotypes. Seventy-six (67%) patients had LL, 35 (31%) had LM, and 2 (2%) had MM genotypes. We observed no impact of PON1 polymorphisms on lipid parameters posttreatment. A significant increase was observed in the serum PON1 activity from a median (range) of 47.92 U/L (9.03-181.25) to 72.22 U/L (7.64-244.44) (P < 0.05) following statin treatment, which was independent from high-density lipoprotein (HDL) concentration. This increase was significantly greater in QQ compared to QR and RR genotypes (P = 0.01). To conclude, the important antioxidant properties of statins are exerted via the rise in serum PON1 activity, independent of HDL cholesterol concentrations. The increase was greater in individuals with QQ genotype. Future large-scale studies will validate the premise that QQ homozygotes see added benefits from statin treatment compared to R carriers. In the meantime, PON1 enzymatic activity remains an important marker to be measured while assessing pleotropic effects of statins in CAD.

Comparison of oxidative stress status and quality of life in participants with type 2 diabetes mellitus according to treatment modality

Background

Oxidative stress triggered by hyperglycemia in diabetic patients leads to macrovascular and microvascular complications, resulting in deterioration in the quality of life.

Aims

This study aimed to compare the oxidative stress status and quality of life in participants with type 2 diabetes mellitus according to treatment modality.

Patients and Methods

Ninety type 2 diabetes mellitus participants aged between 40 and 60 years were included in the study. Forty-five participants were receiving oral antidiabetic drugs and 45 participants were receiving insulin therapy. Total antioxidant status, total oxidant status, and paraoxonase-1 were measured and oxidative stress indices were calculated. The SF-36 quality of life questionnaire was applied to the participants.

Results

The total oxidant status and oxidative stress indices values were higher in the insulin-treated group than in the group treated with oral antidiabetic drugs. Paraoxonase-1 activities of the oral antidiabetic drugs-treated group were statistically significantly higher than the insulin-treated group. In the oral antidiabetic drugs-treated group, the physical function, social function, and pain subscale scores were higher than that of the insulin-treated group. In all participants, a negative correlation between total antioxidant status and fasting blood glucose and hemoglobin A1c, a positive correlation between total oxidant status and hemoglobin A1c and triglyceride, and a positive correlation was found between oxidative stress indices and fasting blood glucose and hemoglobin A1c.

Conclusions

It was found that oxidative stress parameters were higher and quality of life was worse in the insulin-treated participants than participants treated with oral antidiabetic drugs. These results may be closely related to more severe chronic complications in insulin-dependent diabetes.

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.

Association of Genes Related to Oxidative Stress with the Extent of Coronary Atherosclerosis

Oxidative stress is believed to play a critical role in atherosclerosis initiation and progression. In line with this, in a group of 1099 subjects, we determined eight single nucleotide polymorphisms (SNPs) related to oxidative stress (PON1 c.575A>G, MPO c.−463G>A, SOD2 c.47T>C, GCLM c.−590C>T, NOS3 c.894G>T, NOS3 c.−786T>C, CYBA c.214C>T, and CYBA c.−932A>G) and assessed the extent of atherosclerosis in coronary arteries based on Gensini score. An increased risk of having a Gensini score in the higher half of the distribution was observed for the PON1 c.575G allele (odds ratio (OR) = 1.27, 95% confidence interval (CI): 1.004–1.617, p = 0.046). Next, the genetic risk score (GRS) for the additive effect of the total number of pro-oxidative alleles was assessed. We noted an increase in the risk of having a Gensini score above the median with the maximum number of risk alleles (OR = 2.47, 95% CI: 1.19–5.23, p = 0.014). A univariate Spearman’s test revealed significant correlation between the total number of pro-oxidant alleles (GRS) and the Gensini score (ρ = 0.068, p = 0.03). In conclusion, the PON1 c.575A>G variant and the high number of risk alleles (GRS) were independent risk factors for a high Gensini score. We suggest, however, that GRS might occur as a more valuable component in adding a predictive value to the genetic background of atherosclerosis.

Association of PON1 gene polymorphisms and enzymatic activity with risk of coronary artery disease

Background: The present case-control study evaluated the association of PON1 gene polymorphisms and enzyme activity in the western Indian population. Materials & methods: Angiographically proven coronary artery disease (CAD) formed the cases. PON1 polymorphisms (Q192R, L55M) and enzymatic activity (paraoxonase) were assessed. Results: A total of 502 participants (251 per group) were studied. PON1 Q192R and L55M polymorphisms were not associated with the risk of CAD. Notably, a weak association was observed between Q192R polymorphisms and the risk of CAD. CAD patients had significantly lower PON1 enzymatic activity (U/L) as compared with the controls regardless of the genotype. Conclusion: Low serum PON1 activity was confirmed to be an independent predictor for the risk of CAD.

Genetic associations and serum paraoxonase levels with atherosclerosis in western Iranian patients

The oxidative modification of low-density lipoprotein (LDL) in the arterial wall plays a pivotal role in the initiation and progression of atherosclerosis which is a complex and progressive disorder. Paraoxonase1 (PON1), which is required for lipid metabolism, is believed to protect LDL from oxidation. The relationship between PON1 gene Leusin55Methionin (L55M) and Glutamine192Arginine (Q192R) polymorphisms in western Iranians with atherosclerosis and its association with enzyme activity and oxidized low-density lipoprotein (oxLDL) were examined in the present study. In this study, blood specimens were collected from 145 healthy individuals and 154 patients with atherosclerosis proven by angiography referred to Shahid Madani Hospital, Khorramabad, Iran. Genomic deoxy ribonucleic acid (DNA) was extracted from whole blood. For all the subjects, restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR) was carried out for the detection of L55M and Q192R polymorphisms. PON1 enzyme activity and the level of oxLDL were also evaluated. There was a 3.114-fold increase in the risk of developing atherosclerosis in the subjects presenting the PON1L55M, MM genotype compared to those with the LL genotype (OR 3.114; 95% CI 1.412-6.870). PON1Q192R polymorphism in the PON1 gene was not associated with atherosclerosis. Patients with atherosclerosis had significantly higher oxLDL and reduced PON1 enzyme activity (P < 0.05) compared to the controls. There was no association between the type of genotype, enzyme activity, and oxLDL level. It has been concluded that PON1L55M polymorphism and MM genotype are associated with an increased risk of coronary artery disease (CAD) in Iranian patients with atherosclerosis. We did not find any relationship between PON1Q192R polymorphism and atherosclerosis.

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.

Paraoxonase-1 Q192R polymorphism and its association with hs-CRP and fasting blood glucose levels and risk of coronary artery disease

AIMS

Paraoxonase-1 (PON1) has been shown to protect low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) against oxidative-modification and thereby might protect against coronary-artery-disease (CAD). Here we explored the relationship of a genetic variant (a substitution (R) Arg with (Q) Gln at position 192) of PON1 in 250 patients with/without CAD.

MATERIALS AND METHODS

Genotyping of PON1 Q192R was carried out using Real-Time-PCR TaqMan-based-probe. Demographic-characteristics and biochemical-analyses, including fasting blood sugar (FBS), HDL, LDL, triglycerides (TG) and C-reactive protein (CRP) were evaluated. Univariate/multivariate analyses were performed to determine the association of the genetic polymorphism and CAD as well as with clinical-characteristics of population.

RESULTS

Our findings showed that RR-genotype was more frequent in CAD-patients, compared to the wild-type genotype. Moreover, CAD patients with RR-genotype had an odd ratio of 5.0 (95% CI: 1.3-18.6; p = 0.017), versus wild-type genotype, in multivariate-analysis. Of note we also observed that CAD-patients with QQ-genotype had a significantly lower Hs-CRP level, compared to the RR-genotype.

CONCLUSION

we demonstrate that PON1-Q192R-polymorphism was associated with CRP and FBS levels; R-allele of PON1-Q192R may be an independent risk factor for CAD. Further studies are warranted to determine the value of this marker as a surrogate marker in CAD patients.

Paraoxonase-1 genetic polymorphisms in organophosphate metabolism

Organophosphates (OPs) are a class of chemicals commonly used in agriculture as pesticides, that can often lead to severe toxicity in humans. Paraoxonase-1 (PON1) belongs to a family of A-esterases and hydrolyses several OPs while also serving other biological roles. Two main genetic polymorphisms have been shown to affect enzymatic ability; an A > G transition in the 192nd position (192 Q/R, rs662), and an A > T at codon 55 (55 M/L, rs854560). In this review, we searched PubMed for relevant articles published from its inception till June 2018 and included publications from 1996 to 2018. We aimed to address the distribution of the polymorphisms in various populations, the way they affect enzymatic activity and the possible use of PON1 as a biomarker. The polymorphisms present great heterogeneity between populations, with the data being clearer over 192 Q/R, and this heterogeneity is related to the phylogenetic origins of each population. Concerning enzymatic activity, the different genotypes react better or worse to different OP substrates, with studies presenting a variety of findings. Detecting the "paraoxonase status" of an individual -referring to PON1 function- seems to be important in predicting OP toxicity, as studies have shown that some specific-genotype individuals present symptoms of toxicity in higher rates than others. We are strongly convinced that in order for the scientific community to reach a consensus over which polymorphisms confer susceptibility to toxicity and whether PON1 can eventually be used as a biomarker, more studies need to be carried out, since the data thus far does not seem to reach a universal conclusion.

Distribution of genetic variants of oxidative stress metabolism genes: Paraoxonase 1 (PON1) and Glutathione S-transferase (GSTM1/GSTT1) in a population from Southeastern Mexico

BACKGROUND

Paraoxonase 1 (PON1) and glutathione S-transferases (GSTs) are involved in the biotransformation of xenobiotics. Variation in the enzyme concentration and activity suggests individual differences for the degree of protection against oxidative stress.

AIM

This study analysed the distribution of SNPs Q192R, L55M (PON1) and variants in GSTM1 and GSTT1 genes in a population from Southeastern Mexico.

SUBJECTS AND METHODS

One hundred and fifty-one Mexican Mestizo healthy volunteers were included. PON1 polymorphisms were determined by Taqman allele discrimination real time-PCR, whereas GSTM1 and GSTT1 genes were determined with a multiplex PCR-based method.

RESULTS

All genotypes were in Hardy-Weinberg equilibrium, except for GSTM1. The genotypic distributions of Q192R and L55M were 22% QQ, 48% QR, 30% RR, 62% LL, 34% LM and 4% MM, respectively, whereas the allele frequencies were 0.46 (Q), 0.54 (R), 0.79 (L) and 0.21 (M). The most frequent haplotype was R/L (46.7%). It was found that 31% and 9% of the individuals had the GSTM1 and GSTT1 null genotype, respectively. The frequency of the combined null genotype GSTM1*0/GSTT1*0 was 4.64%.

CONCLUSION

The results showed that the frequencies of polymorphisms of PON1, GSTM1 and GSTT1 in the Yucatán population differ to those observed in other ethnic groups and provide useful data for epidemiological studies.

Effects of paraoxonase 1 gene polymorphisms on heart diseases: Systematic review and meta-analysis of 64 case-control studies

BACKGROUND

Associations between paraoxonase 1 (PON1) gene polymorphisms and heart diseases (HD) risk remain inconsistent. In order to obtain address this issue we performed a meta-analysis to assess the association between the L55M and Q192R polymorphisms of PON1 gene and heart diseases risk.

METHODS

Relevant studies were enrolled by searching databases systematically. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to calculate the strength of association. Subgroup analyses were conducted for diagnostic and ethnicity. The heterogeneity among each of the studies was calculated by using Cochran Qtest and the inconsistency index (I), and Begg's funnel plot and Egger's tests were performed to evaluate publication bias.

RESULT

Sixty four studies involving a total of 19,715 cases and 33,397 controls were included in this meta-analysis. We found that the L55M polymorphism showed a significant association with heart diseases in Europeans (OR 1.44, 95%CI 1.33-1.56) and Asians (OR 1.18, 95%CI 1.03-1.35). This meta-analysis also showed a protective association of Q192R polymorphism with HD in Asian (OR 0.49, 95%CI 0.37-0.66) and African populations (OR 0.67, 95%CI 0.53-0.84). The 192R allele significantly decreased the risk of myocardial infarction (OR 0.75, 95%CI 0.57-0.99) and coronary artery disease (OR 0.91, 95%CI 0.84-0.98); however, individuals with 192Q allele had a markedly increased risk of coronary artery disease development (OR 1.38, 95%CI 1.22-1.56).

CONCLUSION

This study demonstrated that the genetic risk for heart diseases is associated with the PON1 gene polymorphisms. L55M polymorphism is a risk factor and Q192R polymorphism is protective in certain populations. It is worth noting that the 192Q allele may be a risk factor to develop coronary artery disease.

Association between Paraoxonase 1 (PON1) Polymorphisms and the Risk of Acute Coronary Syndrome in a North African Population

The purpose of the present study was to investigate the distribution of PON1 Q192R and L55M polymorphisms and activities in a North African population and to determine their association with cardiovascular complications. The prevalence of the QQ, QR, RR, LL, LM, and MM genotypes in the study population was 55.4%, 34.09%, 9.83%, 41.97%, 48.20%, and 9.83% respectively. The Q, R, L, and M alleles had a gene frequency of 0.755, 0.245, 0.67, and 0.33, respectively. The PON1 192 RR genotype was significantly more prevalent among ACS patients than among healthy subjects. There was a 4.33-fold increase in the risk of ACS in subjects presenting the PON1 192 RR genotype compared to those with the QQ genotype (OR=4.33; 95% CI=1.27–17.7). There was a significantly different distribution of PON1 L55M in the ACS patient groups (UA, STEMI, NSTEMI). Moreover, individuals presenting the PON1 55MM genotype present a higher risk for ACS than those with LL genotype (OR=3.69; 95% CI=1.61–11.80). Paraoxonase activities were significantly lower in coronary patients than in healthy subjects. The decrease in PON1 activity was inversely correlated with the number of concomitant risk factors for CVD (r=0.57, p<0.0001). The results of the present study suggested that the PON1 R and M alleles may play a role in the pathogenesis of cardiac ischemia in our North African population and that a decrease in PON1 activity may be a valuable marker for monitoring the development of the atherosclerosis process and the associated cardiovascular complications.

Interaction effects between Paraoxonase 1 variants and cigarette smoking on risk of coronary heart disease in a Singaporean Chinese population

OBJECTIVE

Paraoxonase 1 (PON1) plays an important role in reducing the risk of coronary heart disease (CHD). Smoking is known to reduce PON1 activity. We aimed to investigate the effects of interactions between PON1 variants and smoking on CHD in the Singaporean Chinese population.

METHODS

In a case-control study nested within Singapore Chinese Health Study (N=1914), subjects with and without CHD were classified into never-smokers and ever-smokers (ever smoked at least one cigarette a day for 1 year or longer). Associations at four independent SNPs at the PON1 locus (rs3735590, rs3917550, rs662, rs3917481) with CHD were evaluated using logistic regression, before/after stratification on smoking status. Interactions between smoking and PON1 variants were analyzed with likelihood ratio tests, by including the SNP*smoking interaction term in regression analyses.

RESULTS

The T allele at the coding SNP, rs662, was associated with higher risk of CHD in ever-smokers only (OR=1.35, 95% CI 1.08-1.68; adjusted P=0.036). At the miR-SNP, rs3735590, carrying at least one copy of minor allele T was associated with increased risk of CHD in a dominant manner in never-smokers only (OR=1.53, 95% CI 1.11-2.11; adjusted P=0.036). Significant interactions between two PON1 SNPs and smoking in relation to CHD risk were identified (adjusted P=0.012 for rs662; adjusted P=0.044 for rs3735590). These associations remained significant after adjustment for known CHD risk factors and upon correction for multiple tests.

CONCLUSIONS

Two PON1 SNPs, rs662 and rs3735590, were found to significantly interact with cigarette smoking to modulate the risk of CHD in the Singaporean Chinese population.

Effects of anaerobic training on paraoxonase-1 enzyme (PON1) activities of high density lipoprotein subgroups and its relationship with PON1-Q192R phenotype

AIM

Paraoxonase-1 (PON1) is an antiatherosclerotic enzyme located on high-density lipoprotein (HDL). The effects of anaerobic exercise on PON1 activity are unknown. Here we investigated the effects of anaerobic judo training on three different activities of same PON1 enzyme (TDPON1), including basal PON1, salt-stimulated PON1 (SPON1), and arylesterase (AE) activities, of serum, HDL, and HDL subgroups (HDLs; HDL and its subgroups) and its relationship with PON1-Q192R phenotype (PON1P).

METHODS

Our study included 18 Turkish national female judoists (mean age: 17.9 ± 0.8 years). Before and after 5 months of anaerobic training, critical speed (CS), TDPON1 activities, cholesterol levels in the serum and supernatants of HDLs obtained by polyethylene glycol, and other major blood lipids and lipoproteins (BLLPs) including triglycerides were determined using blood samples taken after overnight fasting. PON1P groups (PGs) were categorized as QQ (QG; persons with low activity) and R carriers (QR + RR) (RG; persons with high activity) according to SPON1/AE activity ratios. The results were considered statistically significant at P ≤ 0.05.

RESULTS

Anaerobic training resulted in significantly increased the cholesterol levels of HDLs (except HDL2-C) in all subjects, but not HDLs-C in PGs. Anaerobic training resulted in significant increases in most TDPON1 activities of serum and HDLs in all subjects and (except AE) in PGs, whereas SPON1 and HDL2 AE activities increased only in the RG, which was related to PON1P. However, PON1P was not related to other measured markers, including basal BLLP profiles.

CONCLUSIONS

Anaerobic training improved most TDPON1 activities of serum and HDLs and HDLs -C levels (except HDL2-C) in all subjects, but not HDLs-C in PGs. The beneficial effects of anaerobic training on SPON1 and HDL2 AE activities were depend on PON1P. The lack of response of HDL2-C to anaerobic exercise will require further research.

Paraoxonase 1 and its relationship with pesticide biomarkers in indigenous Mexican farmworkers

OBJECTIVE

Biomarkers of pesticide toxicity and paraoxonase 1 (PON1) phenotype and genotypes were evaluated in indigenous Mexican farmworkers exposed mainly to organophosphate (OP) pesticides.

METHODS

Acetylcholinesterase, butyrylcholinesterase, and PON1 activities--arylesterase and CMPAase activities--were evaluated spectrophotometrically. PON1 55 and 192 polymorphisms were determined by real-time polymerase chain reaction. Hematological parameters were evaluated using a cytometer.

RESULTS

Butyrylcholinesterase and arylesterase activities were lower in farmworkers, who also showed lower levels of leukocytes but higher percentages of lymphocytes when compared with the nonexposed group. Our results showed a high frequency of OP, high hydrolysis-related PON1 alleles (LL/QR and LL/RR) in the study population. An association was observed between CMPAase activity and PON1Q192R polymorphism.

CONCLUSIONS

Our results suggest that pesticide exposure modifies biochemical and hematological biomarkers in the study population, and that the phenotype of PON1 (CMPAase) is a sensible susceptibility biomarker of OP pesticide toxicity.

Exploring the role of paraoxonases in the pathogenesis of coronary artery disease: a systematic review

Paraoxonases (PON) are three enzymes (PON1, PON2 and PON3) that play a role in the organism’s antioxidant system; alterations in which are associated with diseases involving oxidative stress. In this review, we summarize the evidence of PON related to the pathogenesis of coronary artery disease (CAD) and atherosclerosis. We searched three electronic databases (PubMed, Scopus and Cochrane Database) with no date limit. All of the articles selected investigated PON enzymatic activity and/or PON gene polymorphisms. The selection focused on PON in relation to atherosclerosis, CAD and myocardial infarction. The exclusion criteria were a sample size <100 patients, non-human studies, editorials and systematic reviews without restrictions on the country of origin. With these criteria, we identified thirty-five prospective studies published between 1986 and 2014 with a total of 28,164 participants. The relationship between PON gene polymorphisms and CAD was not conclusive, but most studies support the concept that alterations in PON1 enzymatic activity levels do influence atheroma formation. Conversely, relationships between PON2 and PON3 vs. CAD have not been extensively investigated. Our review of the current data concludes that the bases of paraoxonases involvement in atherosclerosis are poorly understood and that this issue requires future comprehensive, multi-centered studies.

Human serum paraoxonase gene polymorphisms, Q192R and L55M, are not associated with the risk of cerebral infarction in Chinese Han population

OBJECTIVES

It has been reported that human serum paraoxonase (PON1) gene is associated with coronary heart disease (CHD) and diabetes mellitus (DM). However, little is known about the role of PON1 gene polymorphism in cerebral infarction (CI). For this, we have investigated the relationship between PON1 gene polymorphisms, Q192R and L55M, and CI in Chinese Han population.

METHODS

The PON1 genotypes, Q192R and L55M, from 153 CI patients and 153 healthy individuals, were determined by polymerase chain reaction (PCR) and restriction enzyme digestion. Their allele frequencies were then determined. The association of the PON1 gene polymorphism with the risk of CI was analysed by statistical analysis software.

RESULTS

The frequencies of PON1-Q192R genotypes in CI and control group are 13.7 and 9.8% (QQ), 51.6 and 53.6% (QR), 34.6 and 36.6% (RR) respectively. There is no significant difference in PON1-Q192R genotype (p=0.566) and allele frequencies (p=0.505) between CI patients and controls. The frequencies of PON1-55 genotypes in the CI and control group are 96.7 and 93.5% (LL), 3.3 and 6.5% (LM) respectively. No MM genotype was found in both CI and control group. No significant difference in genotype (p=0.289) and allele (p=0.296) distribution between CI patients and controls was observed.

DISCUSSION

Our results suggest that the human serum paraoxonase polymorphisms, Q192R and L55M, are not associated with the risk of cerebral infarction in Chinese Han population.

The Q192R polymorphism of the paraoxonase 1 gene is a risk factor for coronary artery disease in Saudi subjects

Paraoxonase-1 (PON1) is a HDL-bound antioxidant enzyme that protects LDL from oxidative modification. Discovery of the antioxidant properties of PON1 led to extensive research on its role in the initiation and progression of atherosclerosis. The Q192R (rs662; A/G) polymorphism, which results in the glutamine to arginine substitution at position 192, of the PON1 gene has been linked to increased atherosclerosis risk in several but not all population studies. Besides genetic factors, environmental variables and ethnicity have been implicated as factors responsible for the ambiguity in relating the PON1 gene with atherosclerotic risk. Here, we tested the association of the Q192R polymorphism with coronary artery disease (CAD) in Saudi ethnic subjects taking environmental factors into consideration. The genomic DNA samples from 121 angiographically confirmed CAD cases and 108 normal healthy control subjects were genotyped by PCR-RFLP analysis. The distribution of QQ, QR, and RR genotypes was significantly different between cases and controls (p < 0.005). The RR genotype was associated with CAD risk independently of several established risk factors including age, gender, smoking, obesity, and diabetes (OR 2.2, 1.4-7.4, p < 0.01). Genotype-based stratification of demographic and biochemical data revealed that the RR genotype has proatherogenic properties. This study, thus, identifies the Q192R polymorphism as an additional risk factor for CAD in the Saudi population and suggests that it may have prognostic value. The negative effect of this genetic variant is presumably due to the diminished ability of the RR variant genotype of PON1 to blunt LDL oxidation.

CYP2C19 and PON1 polymorphisms regulating clopidogrel bioactivation in Chinese, Malay and Indian subjects

AIM, MATERIALS & METHODS: We investigated the functional significance of CYP2C19*2, *3, *17 and PON1 Q192R SNPs in 89 consecutive Asian patients on clopidogrel treatment and the prevalence of functionally significant polymorphisms among 300 Chinese, Malays and Asian Indians.

RESULTS

Both CYP2C19 loss-of-function alleles (*2 or *3) were associated with higher platelet reactivity while the CYP2C19 gain-of-function allele (*17) had lower platelet reactivity. For PON1, the median PRI was not significantly different between the QQ, QR and RR groups. The allele frequencies of CYP2C19*2, CYP2C19*3 and CYP2C19*17 were 0.280, 0.065 and 0.010 (rare) for Chinese, 0.310, 0.050 and 0.025 for Malays, and 0.375, 0.010 (rare) and 0.165 for Indians, respectively.

CONCLUSION

Our data suggest that genotyping studies to investigate clopidogrel response should include CYP2C19*2 and *3 but not *17 polymorphisms in Chinese, and CYP2C19*2 and *17 polymorphisms but not *3 in Indians. All three polymorphisms should preferably be genotyped in Malays.

Interaction of folate intake and the paraoxonase Q192R polymorphism with risk of incident coronary heart disease and ischemic stroke: the atherosclerosis risk in communities study

PURPOSE

To investigate the potential interaction between folate intake and the paraoxonase 1 (PON1) Q192R polymorphism with the risk of incident coronary heart disease (CHD) and ischemic stroke in the Atherosclerosis Risk in Communities study, a population-based prospective cohort of cardiovascular disease in 15,792 white and African-American subject.

METHODS

Race-stratified Cox proportional hazards models were performed to examine the interaction between folate intake and the PON1 Q192R polymorphism.

RESULTS

A significant inverse association between folate intake and risk of incident CHD among white subjects was found (hazard rate ratio, 1.30; 95% confidence interval, 1.09-1.56; P = .004; folate intake ≤155 μg vs ≥279 μg, reference group). An interaction effect was observed between the dominant genetic model and folate intake with regards to incident ischemic stroke in white subjects (hazard rate ratio, 0.68; 95% confidence interval, 0.91-0.99; and 1.24 from 1st-4th quartile, respectively; P-trend = .05).

CONCLUSIONS

There was an interaction between folate intake and PON1 Q192 polymorphism with regard to the risk of ischemic stroke in white subjects. Future studies should investigate the interaction between additional polymorphisms within the PON1 gene and genetic variants in other folate metabolizing genes with folate intake on the risk of incident CHD and stroke.

Distribution profile of paraoxonase phenotypes among the Gujaratis

BACKGROUND:

Paraoxonase (PON1) can hydrolyze organophosphate pesticides (OP) and has a key role in the susceptibility of human in OP toxicity. The human-enzyme shows polymorphism and variations in the distribution profile of its phenotypes among different ethnic groups have been observed.

AIMS:

To see the distribution pattern of total PON1 activity in 45 healthy attendants of poisoning cases; 121 healthy unrelated farm-labours and 59 normal subjects of trauma.

MATERIALS AND METHODS:

The PON1 activities from serum/plasma samples of these healthy normal individuals were estimated with/without addition of 1M NaCl in order to determine salt-stimulated and basal activity. The PON 1 phenotypes were determined on the basis of percent activation of enzyme activity.

RESULTS:

Tri-modal distribution of basal PON1 activity was observed among all these individuals. 52.0% of the individuals belonged to Phenotype A, 46.6% to phenotype AB while 1.4% to Phenotype B with gene frequency of allele-A and allele-B being 0.753 and 0.247 respectively in excellent agreement with Hardy-Weinberg equilibrium.

CONCLUSION:

Maximum number of individuals belonged to phenotype-A (low PON1 activity) showing potential vulnerability towards Op-poisoning.

Synergism between paraoxonase Arg 192 and the angiotensin converting enzyme D allele is associated with severity of coronary artery disease

We have previously shown that angiotensin-converting enzyme (ACE) gene D allele is an independent risk factor for early onset coronary artery disease (CAD). Little is known about the concomitant presence of the ACE gene D allele and paraoxonase (PON1) codon 192 arginine (Arg) on the severity of CAD. Regarding the high rate of CAD among Iranians the aim of present study was to examine the hypothesis of synergistic effects between ACE-D and PON1-Arg alleles on predisposition and the severity of CAD in our population. The PON1 192 and ACE insertion/deletion (I/D) genotypes were detected by PCR-RFLP and PCR, respectively in 414 individuals undergoing their first coronary angiography. Patients were placed into one of two groups: CAD and control without CAD or diabetes. We mentioned the synergistic effects of both genes and not ACE gene alone is a risk factor for CAD. We found that PON1 Arg 192 and ACE D allele act synergistically to increase the risk of CAD (OR 1.3, P = 0.044). Our results showed a significant correlation between the possession of both PON1 192 Arg and the ACE D allele and the extent of CAD in CAD patients and CAD subjects without diabetes, represented by the increased frequency of three-vessel disease with OR 2.7, P = 0.046; χ(2) = 4, P = 0.046 and OR 2.4, P = 0.051; χ(2) = 3.8, P = 0.051, respectively. We found that PON1 Arg 192 and ACE D alleles act synergistically to increase the risk of CAD in CAD patients and CAD subjects without diabetes from west of Iran, who have high frequency of three-vessel disease. Our data suggest that PON1 192 Arg and the ACE D allele in combination with each other can be important independent risk factor for severity of CAD in patients carrying both PON1 192 Arg and the ACE D allele in a west population of Iran.

Paraoxonase 1 (PON1) polymorphisms, haplotypes and activity in predicting cad risk in North-West Indian Punjabis

BACKGROUND

Human serum paraoxonase-1 (PON1) prevents oxidation of low density lipoprotein cholesterol (LDL-C) and hydrolyzes the oxidized form, therefore preventing the development of atherosclerosis. The polymorphisms of PON1 gene are known to affect the PON1 activity and thereby coronary artery disease (CAD) risk. As studies are lacking in North-West Indian Punjabi's, a distinct ethnic group with high incidence of CAD, we determined PON1 activity, genotypes and haplotypes in this population and correlated them with the risk of CAD.

METHODOLOGY/PRINCIPAL FINDINGS

350 angiographically proven (≥ 70% stenosis) CAD patients and 300 healthy controls were investigated. PON1 activity was determined towards paraoxon (Paraoxonase; PONase) and phenylacetate (Arylesterase; AREase) substrates. In addition, genotyping was carried out by using multiplex PCR, allele specific oligonucleotide -PCR and PCR-RFLP methods and haplotyping was determined by PHASE software. The serum PONase and AREase activities were significantly lower in CAD patients as compared to the controls. All studied polymorphisms except L55M had significant effect on PONase activity. However AREase activity was not affected by them. In a logistic regression model, after adjustment for the conventional risk factors for CAD, QR (OR: 2.73 (1.57-4.72)) and RR (OR, 16.24 (6.41-41.14)) genotypes of Q192R polymorphism and GG (OR: 2.07 (1.02-4.21)) genotype of -162A/G polymorphism had significantly higher CAD risk. Haplotypes L-T-G-Q-C (OR: 3.25 (1.72-6.16)) and L-T-G-R-G (OR: 2.82 (1.01-7.80)) were also significantly associated with CAD.

CONCLUSIONS

In conclusion this study shows that CAD patients had lower PONase and AREase activities as compared to the controls. The coding Q192R polymorphism, promoter -162A/G polymorphism and L-T-G-Q-C and L-T-G-R-G haplotypes are all independently associated with CAD.

Paraoxonase 1 polymorphism Q192R affects the pro-inflammatory cytokine TNF-alpha in healthy males

Background

Human paraoxonase 1 (PON1) is an HDL-associated enzyme with anti-oxidant/anti-inflammatory properties that has been suggested to play an important protective role against coronary heart diseases and underlying atherogenesis. The common PON1 Q192R polymorphism (rs662, A>G), a glutamine to arginine substitution at amino acid residue 192, has been analyzed in numerous association studies as a genetic marker for coronary heart diseases, however, with controversial results.

Findings

To get a better understanding about the pathophysiological function of PON1, we analyzed the relationships between the Q192R polymorphism, serum paraoxonase activity and serum biomarkers important for atherogenesis. Genotyping a cohort of 49 healthy German males for the Q192R polymorphism revealed an allele distribution of 0.74 and 0.26 for the Q and R allele, respectively, typical for Caucasian populations. Presence of the R192 allele was found to be associated with a significantly increased paraoxonase enzyme activity of 187.8 ± 11.4 U/l in comparison to the QQ192 genotype with 60.5 ± 4.9 U/l. No significant differences among the genotypes were found for blood pressure, asymmetric dimethylarginine, LDL, HDL, triglycerides, and cholesterol. As expected, MIP-2 alpha a cytokine rather not related to atherosclerosis is not affected by the PON1 polymorphism. In contrast to that, the pro-inflammatory cytokine TNF-alpha is enhanced in R192 carriers (163.8 ± 24.7 pg/ml vs 94.7 ± 3.2 pg/ml in QQ192 carriers).

Conclusions

Our findings support the hypothesis that the common PON1 R192 allele may be a genetic risk factor for atherogenesis by inducing chronic low-grade inflammation.

Paraoxonase Arg 192 allele is an independent risk factor for three-vessel stenosis of coronary artery disease

The role of the paraoxonase (PON1) codon 192 polymorphism [glutamine (Q)/arginine (R)] in coronary artery disease (CAD) is controversial. The aim of the present study was to evaluate whether the PON1 gene polymorphism is an independent risk factor for severity of coronary artery disease in patients from west of Iran. The PON1-Arg-192 genotypes were detected by PCR-RFLP in 414 individuals undergoing their first coronary angiography. Patients were placed into one of two groups: CAD and control without CAD or diabetes. The frequency of PON1-Arg-192 allele was significantly higher in the CAD (23.4 vs. 16%, P = 0.032) than in the control group and there was a higher risk of developing CAD (OR = 1.6, P = 0.02). In addition, this difference remained significant after adjustment for without history of diabetes (OR = 1.47, P = 0.048), presence of normolipidemia and absence of history of blood pressure (OR = 1.4, P = 0.05). This result indicated PON1-Arg-192 allele is a risk factor of CAD also when correcting for conventional risk factors. We found a significant association between the PON1-Arg-192 genotype (QR + RR) and the extent of CAD in CAD patients and CAD subjects without diabetes, represented by the increased frequency of three-vessel disease with OR = 1.49, P = 0.046; χ2 = 3.82, P = 0.048 and OR = 1.46, P = 0.05; χ2 = 3.48, P = 0.051, respectively. The CAD patients carrying PON1-Arg-192 genotype (QR + RR) had lower plasma HDL-C level (P = 0.019) and higher plasma LDL-C(P = 0.01) and TG(P = 0.05). Our results indicated that PON1-Arg-192 allele can be important independent risk factor of CAD in a west population of Iran, with carriers of PON1-Arg-192 having an increased frequency of three-vessel disease and also having a distinct plasma lipids profile. Larger collaborative studies are needed to confirm these results.

Are PON1 Q/R 192 and M/L 55 polymorphisms risk factors for diabetes complications in Turkish population?

OBJECTIVES

We investigated whether the human serum paraoxonase (PON1) Q/R 192 and M/L 55 polymorphisms are associated with the complications of the type 2 diabetes (T2D).

DESIGN AND METHODS

Study group was consisted of 50 healthy subjects and 100 type 2 diabetes mellitus (DM) patients. Following measuring of serum PON1 activity, isolation of DNA and genotyping analyses were performed.

RESULTS

PON1 activity of the patients with complications was significantly reduced by 23.5% compared to the group of diabetic patients and by 26.3% than the controls. According to multivariate analysis, we observed a three times significant effect of Q/R 192 polymorphism on the susceptibility to the occurrence of complications.

CONCLUSIONS

Protective effects of paraoxonase against peroxidation of LDL particles are important in T2D complications. Although both of the two polymorphisms are associated, 192 polymorphism seems to be stronger predictor of the risk of diabetic complications.

Smoking is associated with reduced serum paraoxonase, antioxidants and increased oxidative stress in normolipidaemic acute myocardial infarct patients

BACKGROUND

Paraoxonase is a high-density lipoprotein (HDL)-associated enzyme that protects lipoproteins from oxidative modifications and from becoming atherogenic in nature. Smoking is a well-known major cardiovascular risk factor that promotes lipid peroxidation (LP). The present study examined the hypothesis that smoking modulates the activity of paraoxonase and depletes antioxidants.

AIM

The present study evaluated paraoxonase activity, antioxidant status and LP in smoking and non-smoking normolipidaemic acute myocardial infarct (AMI) patients, and results were compared with controls.

SETTINGS AND DESIGN

The serum paraoxonase activities, antioxidants and LP were determined in 86 normolipidaemic patients diagnosed of AMI, and 86 age-sex-matched healthy volunteers served as control.

MATERIAL AND METHODS

Serum paraoxonase activities were measured by enzymatic kit. The glutathione peroxidase, superoxide dismutase and catalase activity was determined by standard methods. Malondialdehyde was measured by the thiobarbituric acid reaction, and conjugated diene levels by the Recknagel and Glende method. Serum uric acid, total bilirubin, serum albumin and lipid profiles were analysed by standard methods.

STATISTICS

The values were expressed as mean±SD, and data from the patients and control were compared using the Student t test.

RESULTS AND CONCLUSION

The total cholesterol/HDL cholesterol ratio, triglycerides, low-density lipoprotein cholesterol, low-density lipoprotein/HDL cholesterol ratio and triglyceride/HDL cholesterol ratio were significantly higher, and HDL cholesterol significantly lower in smokers compared with non-smoking AMI patients. Superoxide dismutase, glutathione peroxidase and catalase were significantly higher in non-smokers compared with smokers. Serum albumin, uric acid and bilirubin were higher in the control compared with smoking AMI patients. The malondialdehyde and conjugated dienes were significantly higher, and paraoxonase activities were significantly lower in smokers compared with non-smokers.

Relationship between Paraoxonase 1 (PON1) gene polymorphisms and susceptibility of stroke: a meta-analysis

Genetic variants of paraoxonase 1 (PON1) were implicated in stroke susceptibility in several case-control association studies. However, the studies have reported apparently conflicting results, rendering precise assessment of the disease risk associated with the variants difficult. A meta-analysis was therefore conducted by including the studies that examined the association between two common polymorphisms (L55M and Q192R) in the coding region of PON1 gene and the risk of stroke. Altogether 10 studies on L55M polymorphism and 11 studies on Q192R polymorphism were included in this meta-analysis. The results showed, although there was no significant association of the 55L allele with stroke [random effects OR = 1.09, 95% CI (0.93, 1.27), P = 0.29], the 192R allele conferred significant risk of stroke in the overall study population [random effects OR = 1.25, 95% CI (1.07, 1.46), P = 0.006]. Same pattern of results as both the allele contrasts was obtained for the homozygote contrasts and the dominant, recessive and additive models. Subgroup analyses for stroke type, age of patients and ethnicity revealed no association of the 55L allele with stroke, whereas the association of the 192R allele persisted significantly in the groups comprising ischemic stroke patients, stroke patients with mean age >60 years and Caucasian subjects. But no significant association of this allele with stroke susceptibility was detected in the East Asian population. Therefore, the results of this meta-analysis indicate, the Q192R polymorphism could be an important risk factor for stroke, especially in the Caucasian population.

The relationship between paraoxonase1-192 polymorphism and activity with coronary artery disease

OBJECTIVE

We tested the association between PON1 polymorphism, PON1 activity, oxidative susceptibility of LDL and coronary artery disease in Egyptians.

METHODS

PON1 polymorphism, serum PON1 activity, lipoprotein oxidation susceptibility and lipid profile were measured.

RESULTS

Levels of HDL and paraoxonase activity were significantly decreased in CAD patients compared to control group, and in patients with three vessels compared to those of single or two vessels disease. High-activity allele (R) has a more atherogenic lipid profile than for the low activity allele (Q). PON1 RR genotype has nine fold risks to develop CAD in Egyptians while those with PON1 QR genotype have four fold risks.

CONCLUSION

The PON1 activity is lower in subject with CAD and there is a significant relationship between activity of PON1 and the severity of coronary atherosclerosis. Also, we provide evidence of a significant association between R allele of the PON1 polymorphism and the development of coronary artery disease.

Genetic polymorphism in paraoxonase 1 (PON1): Population distribution of PON1 activity

Paraoxonase-1 (PON1) is a serum esterase that hydrolyzes the activated oxon form of several organophosphates. The central role of PON1 in detoxification of organophosphate (OP) pesticides was demonstrated in knockout mouse studies, suggesting that human variability in PON1 needs to be considered in health risk assessments involving exposure to these pesticides. The current analysis focused on two genetic loci in which polymorphisms demonstrated to affect PON1 activity. Detailed kinetic studies and population studies found that the *192Q (wild type) allele is more active toward some substrates (such as sarin, soman, and diazoxon) and less active toward others (such as paraoxon or chlorpyrifos) relative to the variant *192R allele. Another allele that affects activity is *55M; PON1 enzyme quantity, rather than specific activity or substrate preference, is altered. The *192R variant occurs commonly with a frequency of 25-64% across the populations analyzed. The *55M allele is less common, occurring in 5-40% of individuals depending upon the ethnic group studied. These activity and allele frequency data were incorporated into Monte Carlo simulations in which the frequency of both variant alleles was simultaneously modeled in Caucasian, African American, and Japanese populations. The resulting Monte Carlo activity distributions were bimodal for the substrate paraoxon with approximately fourfold differences between low- and high-activity modal medians. Differences in activity between total population median and 1st percentile were five- to sixfold. When sarin metabolic variability was simulated, the population distributions were unimodal. However, there was an even greater degree of interindividual variability (median to 1st percentile difference >20-fold). These results show that the combined effects of two PON1 allelic variants yielded a population distribution that is associated with a considerable degree of interindividual variability in enzyme activity. This indicates that assessments involving PON1 substrates need to evaluate polymorphism-related variability in enzyme activity to display the distribution of internal doses and adverse responses. This may best be achieved via physiologically based pharmacokinetic (PBPK) models that input PON1 activity distributions, such as those generated in this analysis, to simulate the range of oxon internal doses possible across the population.

Interethnic variability of plasma paraoxonase (PON1) activity towards organophosphates and PON1 polymorphisms among Asian populations--a short review

Organophosphate (OP) poisoning is a progressively worrying phenomenon as worldwide pesticide production and consumption has doubled. On average, WHO estimates that 3% of agricultural workers in developing Asian countries suffer an episode of pesticide poisoning every year. Furthermore, the threat of OP usage in terrorism is existent, as seen by the subway tragedy in Tokyo in 1995 where sarin was used. Despite these alarming facts, there is currently no global system to track poisonings related to pesticide use. Human serum paraoxonase (PON1) is the enzyme that hydrolyses OP compounds. Serum PON1 levels and activity vary widely among different ethnic populations. Two commonly studied polymorphisms of PON1 are PON1Q192R and PON1L55M. PON1R192 hydrolyses paraoxon faster than PON1Q192 but hydrolyses diazoxon, sarin and soman eight times slower, and vice versa. PON1M55 has lower plasma levels of PON1 than PON1L55. As the prevalence of the different alleles and genotypic distribution vary between the Asian populations we studied, we propose the necessity to study PON1 polymorphisms and its role in OP toxicity in Asian populations. This would help safeguard the proper care of agricultural workers who might be affected by OP poisoning, and alert relevant anti biological terrorism agencies on possible risks involved in the event of an OP attack and provide effective counter measures.

Association between PPARGC1A gene polymorphisms and coronary artery disease in a Chinese population

Peroxisome proliferrator-activated receptor gamma coactivator-1alpha (PGC-1alpha; PPARGC1A) is a coactivator of the nuclear hormone receptor family that participates in the transcriptional programme of lipid metabolism and oxidative stress implicated in atherogenesis. Therefore, in the present study, we investigated PPARGC1A polymorphisms in the prevalence of coronary artery disease (CAD). A case-control study comprising 342 patients with CAD and 334 controls was performed in a Chinese population. Two single nucleotide polymorphisms (Gly482Ser and Thr394Thr) in the PPARGC1A gene were genotyped and compared using the polymerase chain reaction-restriction fragment length polymorphism method. The XA (GA + AA) genotype of Gly482Ser displayed a higher frequency in CAD patients than that in control subjects (P = 0.019; adjusted odds ratio = 1.53; 95% confidence interval 1.06-2.20). No significant difference in Thr394Thr genotype distribution or in Gly482Ser-Thr394Thr haplotype combinations was found between CAD patients and controls. Furthermore, we found that the significantly increased risk of CAD associated with the XA genotypes of Gly482Ser was more evident among subjects who were younger than 64 years of age, female, overweight and with hypertension. The results indicate that the PPARGC1A Gly482Ser polymorphism may contribute to the risk of CAD in the Chinese population investigated.

PON1Q192R polymorphism is associated with lipid profile in Mexican men with Mayan ascendancy

Paraoxonase (PON1) enzyme is associated with high-density lipoproteins (HDL) that prevents low-density lipoprotein (LDL) oxidation. PON1Q192R polymorphism is associated with a risk of coronary heart disease and low HDL levels in case-control studies, but the issue is yet unresolved. Mexico has shown an increase in cardiovascular diseases, and some genetic factors may play a role. Our purpose was to evaluate the association between PON1Q192R and L55M polymorphisms and serum lipid profile in a healthy Mexican population. Ninety unrelated male inhabitants from southeastern Mexico with Mayan ascendancy agreed to participate. Demographic characteristics, lifestyle and medical history were obtained by questionnaire. Lipid profile was determined by enzymatic methods, PON1 activity by using paraoxon and phenylacetate and PON1 genotype by real-time PCR. HDL-cholesterol (HDL-C) levels were associated with genotype: 192RR homozygote subjects had lower HDL-C levels than 192QQ homozygotes, and individuals with 192RR and 192QR genotypes had an odds ratio (OR)=7.05 (95% confidence interval (CI)=1.29-38.34) of having HDL-C <60 mg/dL. Individuals with higher paraoxonase activity (>600.18 U/L) had a slight risk (OR=4.9, 95% CI=0.83-22.02) of having HDL-C <60 mg/dL. PON155LM polymorphism was associated with higher LDL-cholesterol. PON1Q192R polymorphism showed a role in modulating lipid profile: 192RR homozygotes showed the least favorable lipoprotein levels.

Effect of Statins on Serum Apolipoprotein J and Paraoxonase-1 Levels in Patients With Ischemic Heart Disease Undergoing Coronary Angiography

It has been proposed that apolipoprotein J (apo J) and paraoxonase-1 (PON1) correlate with the extent and severity of ischemic heart disease (IHD). This article compares apo J and PON1 serum concentrations, PON1 activity, and the apo J/PON1 ratio in 138 IHD patients (64 statins users and 74 statin nonusers) referred for angiography and possible percutaneous coronary intervention. The effect of statin treatment on apo J and PON1 concentrations, PON1 activity, and the degree of coronary artery stenosis were evaluated. In both groups, apo J levels were increased, whereas PON1 concentration and activity decreased. IHD patients on statins had significantly lower apo J concentration and higher PON1 concentration and activity. Patients on statins had less coronary artery stenosis. High apo J levels, low PON1 levels, low PON1 activity, and a high apo J/PON1 ratio were associated with IHD. Statin treatment reverses these changes, probably by multiple beneficial actions.

Association between the paraoxonase-1 192Q>R allelic variant and coronary endothelial dysfunction in patients with early coronary artery disease

OBJECTIVE

To test the hypothesis that allelic variants of the paraoxonase-1 gene are associated with endothelial dysfunction, an early stage of atherosclerosis.

PATIENTS AND METHODS

We assessed 192Q>R and 55L>M allelic variants of the paraoxonase gene and coronary endothelial function in response to intracoronary acetylcholine in 99 patients (52 with homozygous QQ, 47 with homozygous RR or heterozygous QR). The study was conducted from September 1, 2002, through November 30, 2004.

RESULTS

Of 52 homozygous QQ patients, 39 (75%) had endothelial dysfunction vs 20 (43%) of the 47 RR/QR patients (P=.001), and this association remained significant after adjustment in a multivariable linear regression model (P=.005). In homozygous QQ vs RR/QR patients, epicardial arterial diameter decreased more (% change in diameter, -22%+/-21% vs -9%+/-16%, respectively, P=.002), coronary blood flow increased less (+37%+/-77% vs +75%+/-75%, P=.02) in response to acetylcholine, and oxidized LDL levels were higher. The 55L>M allelic variant was not significantly associated with endothelial dysfunction and had no effect on the association between endothelial dysfunction and the 192Q>R allelic variant.

CONCLUSION

The 192Q>R allelic variant of the paraoxonase-1 gene is associated with coronary endothelial dysfunction. The current study provides further information regarding the potential mechanisms by which this allelic variant contributes to early atherosclerosis in humans.

Synergistic Effects between Q192R Polymorphism of Paraoxonase 1 Gene and Some Conventional Risk Factors in Premature Coronary Artery Disease

BACKGROUND

Genetic susceptibility to coronary artery disease (CAD) may be determined by polymorphic variants of genes encoding isoforms involved in the processes important in the pathogenesis of atherosclerosis, including lipoprotein oxidation. Participation of single polymorphic variants is relatively small; however, its significance may increase in the presence of specific environmental background. The aim of the study was an evaluation of a possible association between R192Q polymorphism of PON1 gene and CAD as well as interactions between polymorphic variants and conventional risk factors of CAD in determining the risk of the disease.

METHODS

We studied 358 subjects: 178 patients with angiographically confirmed CAD and 180 blood donors without history of CAD. Polymorphisms were genotyped using PCR-RFLP method.

RESULTS

We observed statistically significant differences in the frequencies of Q allele and Q allele carriers of PON1 gene between CAD and controls. We also found a strong synergistic effect between Q allele carrier state and smoking, as well as Q allele carrier state and elevated level of total cholesterol.

CONCLUSIONS

The present study revealed an association between carrier state of Q allele of PON1 gene and coronary artery disease as well as synergistic effects between genotype and some conventional risk factors, mainly smoking and elevated level of total cholesterol.

Accuracy and Biological Variation of Human Serum Paraoxonase 1 Activity and Polymorphism (Q192R) by Kinetic Enzyme Assay

Background: Paraoxonase 1 (PON1) phenotype is a better predictor of atherosclerosis risk than are PON1 genetic polymorphisms alone. Larger studies are required to determine the role of PON1 and there is a need for standardized PON1 assays between laboratories.

Methods: We have adapted 5 enzyme kinetic assays for high-throughput automated analysis of PON1 activity. Using different substrates and reaction conditions, we measured PON1 activity and used activity ratios to identify the PON1 Q192R genetic polymorphisms and assessed the accuracy of the genotype assignments in 79 adult study participants by comparing them with genotypes determined by AlwI restriction enzyme digestion of a 176-bp PCR amplification product from genomic DNA. Imprecision was determined using pooled serum and purified enzyme preparations. Biological variability was estimated by analysis of serial samples from 17 individuals. Variability parameters were compared with total cholesterol as a point of reference to a recognized biomarker of coronary heart disease risk.

Results: Salt stimulation and inhibition ratios were 97.4% and 94.7% correct in assigning Q192R genotype, respectively. Analytical imprecision (CV) was 1.0%–3.0% for phenylacetate and paraoxon substrate assays and 3.0%–8.0% for the para-nitrophenylacetate substrate assays. Combination of the 2 ratios into a double ratio resulted in 100% correct genotype classification.

Conclusion: The described methods for measurement of PON1 activity and accurate genotype assignment are rapid and have potential to facilitate the efficient investigation of PON1 status in clinical and epidemiological studies.

Distribution of paraoxonase-1 gene polymorphisms and enzyme activity in a Peruvian population

Paraoxonase-1 (PON1) is a serum esterase associated with high density lipoproteins and capable of detoxifying toxic metabolites of organophosphorus (OP) compounds. Two major polymorphisms have been described in the coding region of the PON1 gene at positions 192 and 55 and at least five in the 5'-regulatory region, the most important at position -108. Depending on the substrate, PON1 192 Q/R polymorphism can affect PON1 enzymatic activity. In the present study, we have determined the distribution of the PON1 192 Q/R and -108 C/T polymorphisms in a Peruvian population and compared the distribution of these polymorphisms with those of other world populations. PON1 phenotype and enzyme activity also were measured as they can influence the population resistance to the toxicity of OP compounds. The genotype distribution at position 192 was: QQ = 0.236, QR = 0.607, and RR = 0.157; and distribution at position -108 was: CC = 0.315, CT = 0.596, and TT = 0.089. The frequencies of the high activity R and C alleles were 0.461 and 0.613, respectively. The frequency of the PON1 192 Q allele was significantly lower than that of American, Caucasian-American, European-Brazilian, and Costa Rican samples. Outside the American continent, the frequency of this allele was lower than for all European countries, Thais, and Indians, but higher than for Chinese or Japanese. Regarding the toxicological importance of these polymorphisms, it was inferred that PON1 phenotyping (assessment of the R alloform) and genotyping (determination of the PON1 -108TT genotype) could be helpful as individual markers of susceptibility. PON1 phenotyping may be useful in further epidemiological studies involving agriculture workers occupationally exposed to OP compounds in developing countries.