Antioxidant effect of atorvastatin is independent of PON1 gene T(-107)C, Q192R and L55M polymorphisms in hypercholesterolaemic patients

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.

Effect of atorvastatin on testosterone levels

BACKGROUND

Statins are one of the most prescribed classes of drugs worldwide. Atorvastatin, the most prescribed statin, is currently used to treat conditions such as hypercholesterolaemia and dyslipidaemia. By reducing the level of cholesterol, which is the precursor of the steroidogenesis pathway, atorvastatin may cause a reduction in levels of testosterone and other androgens. Testosterone and other androgens play important roles in biological functions. A potential reduction in androgen levels, caused by atorvastatin might cause negative effects in most settings. In contrast, in the setting of polycystic ovary syndrome (PCOS), reducing excessive levels of androgens with atorvastatin could be beneficial.

OBJECTIVES

Primary objective To quantify the magnitude of the effect of atorvastatin on total testosterone in both males and females, compared to placebo or no treatment. Secondary objectives To quantify the magnitude of the effects of atorvastatin on free testosterone, sex hormone binding globin (SHBG), androstenedione, dehydroepiandrosterone sulphate (DHEAS) concentrations, free androgen index (FAI), and withdrawal due to adverse effects (WDAEs) in both males and females, compared to placebo or no treatment.

SEARCH METHODS

The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials (RCTs) up to 9 November 2020: the Cochrane Hypertension Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE; Embase; ;two international trials registries, and the websites of the US Food and Drug Administration, the European Patent Office and the Pfizer pharmaceutical corporation. These searches had no language restrictions. We also contacted authors of relevant articles regarding further published and unpublished work.

SELECTION CRITERIA

RCTs of daily atorvastatin for at least three weeks, compared with placebo or no treatment, and assessing change in testosterone levels in males or females.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the citations, extracted the data and assessed the risk of bias of the included studies. We used the mean difference (MD) with associated 95% confidence intervals (CI) to report the effect size of continuous outcomes,and the risk ratio (RR) to report effect sizes of the sole dichotomous outcome (WDAEs). We used a fixed-effect meta-analytic model to combine effect estimates across studies, and risk ratio to report effect size of the dichotomous outcomes. We used GRADE to assess the certainty of the evidence.

MAIN RESULTS

We included six RCTs involving 265 participants who completed the study and their data was reported. Participants in two of the studies were male with normal lipid profile or mild dyslipidaemia (N = 140); the mean age of participants was 68 years. Participants in four of the studies were female with PCOS (N = 125); the mean age of participants was 32 years. We found no significant difference in testosterone levels in males between atorvastatin and placebo, MD -0.20 nmol/L (95% CI -0.77 to 0.37). In females, atorvastatin may reduce total testosterone by -0.27 nmol/L (95% CI -0.50 to -0.04), FAI by -2.59 nmol/L (95% CI -3.62 to -1.57), androstenedione by -1.37 nmol/L (95% CI -2.26 to -0.49), and DHEAS by -0.63 μmol/l (95% CI -1.12 to -0.15). Furthermore, compared to placebo, atorvastatin increased SHBG concentrations in females by 3.11 nmol/L (95% CI 0.23 to 5.99). We identified no studies in healthy females (i.e. females with normal testosterone levels) or children (under age 18). Importantly, no study reported on free testosterone levels.

AUTHORS' CONCLUSIONS

We found no significant difference between atorvastatin and placebo on the levels of total testosterone in males. In females with PCOS, atorvastatin lowered the total testosterone, FAI, androstenedione, and DHEAS. The certainty of evidence ranged from low to very low for both comparisons. More RCTs studying the effect of atorvastatin on testosterone are needed.

PON-1 haplotype (-108C>T, L55M, and Q192R) modulates the serum levels and activity PONase promoting an atherogenic lipid profile in rheumatoid arthritis patients

INTRODUCTION/OBJECTIVE

Paraoxonase 1 (PON1) promotes antioxidant and antiatherogenic activity related to the hydrolysis of oxidized lipids of low-density lipoproteins. In rheumatoid arthritis (RA) patients, it has been reported that low PON1 activity is related to an impaired lipid profile, increasing cardiovascular risk (CVR). The goal of this study was to analyze the effect of common PON1 polymorphisms and haplotypes on enzymatic activity, PON1 serum levels (PON1s), and lipid parameters related to atherogenic profile in RA patients.

METHODS

A cross-sectional study was carried out on 250 Mexican patients with RA. The lipid profile was determined by colorimetric tests. The PON1 activity (CMPAase) was measured by spectrophotometry. The levels of PON1s were determined by ELISA, and the polymorphisms in the PON-1 gene (-108C>T, L55M, and Q192R) were genotyped by the PCR-RFLP method. The haplotypes were estimated and statistical analysis was performed.

RESULTS

The median of the CMPAase activity and PON1 levels was 13.91 U/mL and 24.75 ng/mL, respectively. The CMPAase activity was significantly lower in carriers of -108TT and 192QQ genotypes (β = - 4.09, P = 0.001 and β = - 3.73, P = 0.002, respectively); moreover, the PON1 levels were lower in 192Q allele carriers (P < 0.01). The TLQ haplotype was associated with CMPAase activity < 13.91 U/mL (OR = 2.29, P < 0.001), as well as with levels of PON1s < 24.75 ng/mL (OR = 1.65, P = 0.017). In this study, the CMPAase activity (< 13.91 U/mL) showed a positive association with lower levels of high-density lipoprotein cholesterol (HDL-c; < 40/50 mg/dL), and with a triglycerides/HDL-c ratio > 3%, and a total cholesterol/HDL-c ratio > 4.5/5%, all representatives of an atherogenic risk lipid profile.

CONCLUSIONS

PON1 polymorphisms modulate the CMPAase activity and PON1 levels in Mexican patients with RA. The CMPAase activity < 13.91 U/mL is associated with an atherogenic lipid profile, independently of inflammation markers and treatment with anti-rheumatic drugs. Key Points •The haplotype TLQ is a marker for low PONase activity in rheumatoid arthritis. •The haplotype TLQ is a marker for low PON1 serum levels in rheumatoid arthritis. •The enzymatic PON1 activity represents the best marker for an atherogenic lipid profile in rheumatoid arthritis, in comparison with PON1 levels. •The haplotype TLQ is a marker of low PON1 activity, levels of PON1s, and atherogenic lipid profile, independent of treatment therapy in rheumatoid arthritis.

Q192R polymorphism in the PON1 gene and familial hypercholesterolemia in a Saudi population

BACKGROUND

Familial hypercholesterolemia (FH) is an autosomal dominant condition characterized by abnormal levels of low-density lipoprotein (LDL) in the blood. FH is a risk factor for atherosclerosis and cardiovascular disease. The relationship between the paraoxonase 1 (PON1) gene, atherosclerosis and coronary artery disease has not been studied in Saudi patients.

OBJECTIVE

To investigate the genetic associations of the Q192R polymorphism in the PON1 gene with FH in Saudi patients.

DESIGN

Case-control study.

SETTING

Tertiary care center, Riyadh.

METHODS

Two hundred Saudi patients were enrolled in this study, including 100 patients with FH and 100 healthy controls, during the period from January 2012 to March 2013. Serum was separated from coagulated blood (3 mL) and used for analysis of lipid profiles. Genomic DNA was isolated from anticoagulant-treated blood (2 mL). Genotyping for the Q192R polymorphism was performed by polymerase chain reaction-restriction fragment length polymorphism analysis, followed by 3% agarose gel electrophoresis.

MAIN OUTCOME MEASURE

The strength of association between the Q192R polymorphism and FH in the Saudi population.

RESULTS

We confirmed that QR versus QQ (odds ratio [OR]: 1.55; 95% confidence interval [CI]: 1.05-3.43; P=.03), QR+RR versus QQ (OR: 1.98; 95% CI: 1.13-3.49; P=.01), and R versus Q (OR: 1.68; 95% CI: 1.09- 2.59; P=.01) in the Q192R polymorphism were associated with FH in the Saudi population.

CONCLUSION

In conclusion, the Q192R polymorphism in the PON1 gene is associated with FH in the Saudi population. Our results confirmed that the R allele, QR, and dominant model genotypes were associated with FH.

LIMITATION

Only a single variant (Q192R) was analyzed, and the medical and family histories of the patients were not known.

Pharmacogenetics of paraoxonase activity: elucidating the role of high-density lipoprotein in disease

PON1 is a key component of high-density lipoproteins (HDLs) and is at least partially responsible for HDL's antioxidant/atheroprotective properties. PON1 is also associated with numerous human diseases, including cardiovascular disease, Parkinson's disease and cancer. In addition, PON1 metabolizes a broad variety of substrates, including toxic organophosphorous compounds, statin adducts, glucocorticoids, the likely atherogenic L-homocysteine thiolactone and the quorum-sensing factor of Pseudomonas aeruginosa. Numerous cardiovascular and antidiabetic pharmacologic agents, dietary macronutrients, lifestyle factors and antioxidant supplements affect PON1 expression and enzyme activity levels. Owing to the importance of PON1 to HDL function and its individual association with diverse human diseases, pharmacogenomic interactions between PON1 and the various factors that alter its expression and activity may represent an important therapeutic target for future investigation.

Paraoxonase (PON1 and PON3) Polymorphisms: Impact on Liver Expression and Atorvastatin-Lactone Hydrolysis

Atorvastatin δ-lactone, a major, pharmacologically inactive metabolite, has been associated with toxicity. In a previous study we showed that polymorphisms of UGT1A3 influence atorvastatin δ-lactone formation. Here we investigated the reverse reaction, atorvastatin δ-lactone hydrolysis, in a human liver bank. Screening of microarray data revealed paraoxonases PON1 and PON3 among 17 candidate esterases. Microsomal δ-lactone hydrolysis was significantly correlated to PON1 and PON3 protein (r(s) = 0.60; r(s) = 0.62, respectively; P < 0.0001). PON1 and PON3 were strongly correlated to each other (r(s) = 0.60) but PON1 was shown to be more extensively glycosylated than PON3. In addition a novel splice-variant of PON3 was identified. Genotyping of 40 polymorphisms within the PON-locus identified PON1 promoter polymorphisms (-108T > C, -832G > A, -1741G > A) and a tightly linked group of PON3 polymorphisms (-4984A > G, -4105G > A, -1091A > G, -746C > T, and F21F) to be associated with changes in atorvastatin δ-lactone hydrolysis and expression of PON1 but not PON3. However, carriers of the common PON1 polymorphisms L55M or Q192R showed no difference in δ-lactone hydrolysis or PON expression. Haplotype analysis revealed decreased δ-lactone hydrolysis in carriers of the most common haplotype *1 compared to carriers of haplotypes *2, *3, *4, and *7. Analysis of non-genetic factors showed association of hepatocellular and cholangiocellular carcinoma with decreased PON1 and PON3 expression, respectively. Increased C-reactive protein and γ-glutamyl transferase levels were associated with decreased protein expression of both enzymes, and increased bilirubin levels, cholestasis, and presurgical exposure to omeprazole or pantoprazole were related to decreased PON3 protein. In conclusion, PON-locus polymorphisms affect PON1 expression whereas non-genetic factors have an effect on PON1 and PON3 expression. This may influence response to therapy or adverse events in statin treatment.

Pharmacological and dietary modulators of paraoxonase 1 (PON1) activity and expression: the hunt goes on

Paraoxonase 1 (PON1) is a high density lipoprotein (HDL)-associated enzyme displaying esterase and lactonase activity. PON1 hydrolyzes several organophosphorus (OP) insecticides and nerve agents, a number of exogenous and endogenous lactones, and metabolizes toxic oxidized lipids of low density lipoproteins (LDL) and HDL. As such, PON1 plays a relevant role in determining susceptibility to OP toxicity, cardiovascular diseases and several other diseases. Serum PON1 activity in a given population can vary by at least 40-fold. Most of this variation can be accounted for by genetic polymorphisms in the coding region (Q192R, L55M) and in the promoter region (T-108C). However, exogenous factors may also modulate PON1 activity and/or level of expression. This paper examines various factors that have been found to positively modulate PON1. Certain drugs (e.g. hypolipemic and anti-diabetic compounds), dietary factors (antioxidants, polyphenols), and life-style factors (moderate alcohol consumption) appear to increase PON1 activity. Given the relevance of PON1 in protecting from certain environmental exposure and from cardiovascular and other diseases, there is a need for further mechanistic, animal, and clinical research in this area, and for consideration of possible alternative strategies for increasing the levels and activity of PON1.

The three-gene paraoxonase family: physiologic roles, actions and regulation

The paraoxonase (PON) gene family is composed of three members (PON1, PON2, PON3) that share considerable structural homology and are located adjacently on chromosome 7 in humans. By far the most-studied member is PON1, a high-density lipoprotein-associated esterase/lactonase, also endowed with the capacity to hydrolyze organophosphates, but all the three proteins prevent oxidative stress and fight inflammation. They therefore seem central to a wide variety of human illnesses, including atherosclerosis, diabetes mellitus, mental disorders and inflammatory bowel disease. The major goal of this review is to highlight the regulation of each of the paraoxonase components by diverse nutritional molecules and pharmacological agents as well as a number of pathophysiological events, such as oxidative stress and inflammation. Considerable and detailed cell-based studies and animal model experiments have been provided to allow a thorough scrutiny of PON modulation, which will increase our understanding and ability to target these genes in order to efficiently increase their transcriptional activity and decrease the risks of developing different disorders.

Modulating effect of atorvastatin on paraoxonase 1 activity in type 2 diabetic Egyptian patients with or without nephropathy

The aim of this study was to investigate the modulating effect of atorvastatin on serum paraoxonase 1 enzyme (PON1) activity in type 2 diabetic Egyptian patients with or without nephropathy. The present study was carried out on the following groups: control group, which consisted of 30 healthy persons; Group I, which consisted of 20 type 2 diabetic patients without nephropathy; and Group II, which consisted of 20 type 2 diabetic patients with nephropathy. All the patients selected were under an antidiabetic regimen of insulin, and patients receiving antihypertensive agents were excluded from the follow-up study to avoid drug interaction fallacies. Twenty-two patients (15 without nephropathy and seven with nephropathy) received atorvastatin in individually adjusted oral dosage (range 10-20 mg) once per day for 12 weeks. All cases were subjected to thorough clinical examination and history taking and measurement of serum levels of PON1 activity, malondialdehyde (MDA), glutathione reductase activity, fasting glucose, total cholesterol, triglycerides, high-density lipoprotein (HDL), low-density lipoprotein (LDL), urea, and creatinine. Urine samples were collected for determination of proteinuria. The obtained results showed that PON1 activity and HDL significantly decreased and fasting glucose significantly increased in Group I and Group II when compared to the control group, with significant difference in their levels between Group II and Group I. MDA, total cholesterol, and LDL levels significantly increased and glutathione reductase activity significantly decreased in Group I and Group II when compared to the control group. Urea, creatinine, and proteinuria levels showed significant increase in Group II when compared to the control group and Group I, with nonsignificant difference between control group and Group I. Atorvastatin therapy caused a significant increase in PON1 activity, and serum levels of MDA and glutathione reductase activity were significantly decreased and increased, respectively. Also, total cholesterol, triglyceride and LDL-cholesterol levels were significantly reduced with a significant increase in HDL-cholesterol levels. There was a significant modest reduction in serum urea and creatinine levels as well as in proteinuria level. Fasting glucose level was significantly reduced under the antidiabetic regimen of insulin through the follow-up period. PON1 activity showed a significant negative correlation with glucose and LDL, and a significant positive correlation with HDL in all the studied groups. It could be concluded that atorvastatin with its pleiotropic effects could provide optimal therapeutic intervention to control not only dyslipidemia, but also oxidative stress status with consequent improvement in the course of type 2 diabetes and diabetic nephropathy. More specifically, restoration of PON1 activity by atorvastatin opens a window to investigate other drugs that could provide a new adjuvant therapeutic line for better control of diabetes and diabetic nephropathy. Further research is also recommended to study the distribution of PON1 genetic polymorphism among the Egyptian population to explain the variability in its activity and its relationship with other factors that associate diabetes and its complications.

Benefits and difficulties in measuring HDL subfractions and human paraoxonase-1 activity during statin treatment

Dyslipidaemia including decreased high density lipoprotein cholesterol concentration is one of several factors that have been implicated in increased cardiovascular risk. Since their introduction in the 1980s, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have emerged as the one of the best-selling class of medications to date, with numerous trials demonstrating powerful efficacy in preventing cardiovascular diseases. Although statins have been shown to modestly raise or not alter HDL-cholesterol, their effect on HDL subfractions and on HDL-associated enzymes including human paraoxonase-1 (PON1) has not yet been fully explored. This review summarizes the currently available data on the effect of statins on HDL subfractions and on PON1 activity with a particular emphasis on the clinical relevance of these effects. Moreover, methodological problems of HDL subfraction and PON1 activity determinations are also discussed.

Effect of preoperative atorvastatin therapy on paraoxonase activity and oxidative stress after coronary artery bypass grafting

The aim of this study was to examine the influence of preoperative atorvastatin therapy on oxidative stress in coronary artery bypass grafting (CABG) patients. Forty patients who underwent elective CABG were enrolled into the study. Of these patients, 20 received atorvastatin (Group I) for 15 days prior to surgery and 20 patients did not use any antihyperlipidemic agents preoperatively (Group II). Serum paraoxonase 1 (PON1) and arylesterase activities, and total antioxidant status (TAS) and total oxidant status (TOS) were measured before surgery and at 1, 6 and 24 hours after the operation. Paraoxonase 1 and arylesterase activities (p<0.001) and TAS levels (p<0.001 for 1st hour and p<0.05 for 6th hour) in Group II were significantly reduced at the 1 st and 6th hours after the operation, whereas the activities of the enzymes (p<0.01) and TAS levels (p<0.05) were significantly reduced only at the 1st hour after the operation in Group I. The total oxidant status of both groups was significantly increased at the 1 st hour after operation (p<0.05 for Group I and p<0.01 for Group II). In conclusion, 15 days of preoperative atorvastatin therapy does not significantly change either the serum PON1 activity or the oxidative stress after CABG.

Pharmacogenetics of response to statins

The 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase inhibitors (statins) are among the most commonly prescribed drugs worldwide. On average, statins improve lipid profiles and have been shown to have ancillary beneficial effects on inflammation, platelet activity, and endothelial function. However, variability in drug response exists regardless of the measured phenotype, and genetic variability may be a contributing factor. Recently, there has been an interesting shift in statin pharmacogenetic studies. Novel study designs have been employed and nontraditional candidate genes have been investigated in relation to both lipid and nonlipid responses to statins. This review outlines earlier pharmacogenetic studies and highlights newly published findings that expand on previous work. Furthermore, a framework is provided in which the necessary next steps in research are described, with the ultimate goal of translating pharmacogenetic findings into clinically meaningful changes in patient care.

Effect of rosuvastatin versus atorvastatin treatment on paraoxonase-1 activity in men with established cardiovascular disease and a low HDL-cholesterol

OBJECTIVE

Paraoxonase-1 (PON-1) is a high-density lipoprotein (HDL) associated enzyme involved in the protective mechanisms of HDL. Our aim was to compare the effect of treatment with rosuvastatin and atorvastatin on serum PON-1 activity.

METHODS

We performed a prespecified prospective study in 68 patients, part of a larger, multicentre randomized study--RADAR (Rosuvastatin and Atorvastatin in different Dosages And Reverse cholesterol transport). Patients aged 40-80 years, all men, with established cardiovascular disease and high-density lipoprotein cholesterol (HDL-C) < 1.0 mmol/L (< 40 mg/dL) entered a 6-week dietary run-in period before receiving treatment with rosuvastatin 10 mg or atorvastatin 20 mg daily for 6-weeks. Doses were increased after 6 weeks to rosuvastatin 20 mg or atorvastatin 40 mg and after 12 weeks to rosuvastatin 40 mg or atorvastatin 80 mg daily. Serum PON-1 activity and lipid profile were determined at baseline, 6 and 18 weeks.

RESULTS

After 18 weeks, the rosuvastatin arm showed a significant increase of PON-1 activity (6.39 U/L, p = 0.02) whereas this was not observed in the atorvastatin arm (1.84 U/L, p = 0.77). The difference between groups did not reach significance (p = 0.11). Both rosuvastatin and atorvastatin resulted in significant (p = 0.0001) and similar increases in HDL-C after 6 weeks [0.06 mmol/L (2.32 mg/dL) vs. 0.05 mmol/L (1.93 mg/dL)] and after 18 weeks [0.10 mmol/L (3.87 mg/dL) vs. 0.10 mmol/L (3.87 mg/dL)].

CONCLUSIONS

Rosuvastatin treatment resulted in a significant increment of serum PON-1 activity with increasing dose while this was not observed with atorvastatin.

TagSNP analyses of the PON gene cluster: effects on PON1 activity, LDL oxidative susceptibility, and vascular disease

Paraoxonase 1 (PON1) activity is consistently predictive of vascular disease, although the genotype at four functional PON1 polymorphisms is not. To address this inconsistency, we investigated the role of all common PON1 genetic variability, as measured by tagging single-nucleotide polymorphisms (tagSNPs), in predicting PON1 activity for phenylacetate hydrolysis, LDL susceptibility to oxidation ex vivo, plasma homocysteine (Hcy) levels, and carotid artery disease (CAAD) status. The biological goal was to establish whether additional common genetic variation beyond consideration of the four known functional SNPs improves prediction of these phenotypes. PON2 and PON3 tagSNPs were secondarily evaluated. Expanded analysis of an additional 26 tagSNPs found evidence of previously undescribed common PON1 polymorphisms that affect PON1 activity independently of the four known functional SNPs. PON1 activity was not significantly correlated with LDL oxidative susceptibility, but genotypes at the PON1(-108) promoter polymorphism and several other PON1 SNPs were. Neither PON1 activity nor PON1 genotype was significantly correlated with plasma Hcy levels. This study revealed previously undetected common functional PON1 polymorphisms that explain 4% of PON1 activity and a high rate of recombination in PON1, but the sum of the common PON1 locus variation does not explain the relationship between PON1 activity and CAAD.