PON1 lactonase activity and its association with cardiovascular disease

Follistatin-like 1 (FSTL1) levels as potential early biomarker of cardiovascular disease in a Mexican population

Cardiovascular diseases (CVD) are the leading cause of death globally. In recent years, follistatin-like protein 1 (FSTL1) has been proposed as an emerging potential clinical biomarker of CVD, since its concentration is upregulated in heart failure. The aim of the present study was to evaluate the association of FSTL1 levels and classic biomarkers with the risk of CVD in Mexican population. A case-control study was carried out in patients with cardiovascular diseases (CVD), arterial hypertension, but not CVD (cardiovascular risk factor-CRF), and healthy controls (control group) from the Mexican Institute of Social Security. Lipid profile, homocysteine (Hcys), serum amyloid A (SAA), FSTL1 concentration, PON1 concentration and activities [Arylesterase (ARE), and Lactonase (LAC)] were evaluated. High levels of FSTL1 were found in the CRF group and a positive association of FSTL1 (OR = 4.55; 95% CI 1.29-16.04, p = 0.02) with the presence of arterial hypertension, as well as Hcys (OR, 3.09; 95% CI 1.23-7.76, p = 0.02) and SAA (OR, 1.03; 95% CI 1.01-1.05, p < 0.01) with the presence of CVD. LAC activity (OR, 0.26; 95% CI 0.07-0.94, p = 0.04) and PON1 concentration (OR, 0.17; 95% CI 0.05-0.62, p = 0.01) were associated with a decrease in OR belonging to the group with CVD. Our results suggest that FSTL1 may be a useful biomarker for monitoring cardiovascular risk in clinical settings. However, longitudinal studies are needed to evaluate how FSTL1 could influence the association of PON1 activity and Hcys with CVD.

Paraoxonase 1 and atherosclerosis

Paraoxonase 1 (PON1), residing almost exclusively on HDL, was discovered because of its hydrolytic activity towards organophosphates. Subsequently, it was also found to hydrolyse a wide range of substrates, including lactones and lipid hydroperoxides. PON1 is critical for the capacity of HDL to protect LDL and outer cell membranes against harmful oxidative modification, but this activity depends on its location within the hydrophobic lipid domains of HDL. It does not prevent conjugated diene formation, but directs lipid peroxidation products derived from these to become harmless carboxylic acids rather than aldehydes which might adduct to apolipoprotein B. Serum PON1 is inversely related to the incidence of new atherosclerotic cardiovascular disease (ASCVD) events, particularly in diabetes and established ASCVD. Its serum activity is frequently discordant with that of HDL cholesterol. PON1 activity is diminished in dyslipidaemia, diabetes, and inflammatory disease. Polymorphisms, most notably Q192R, can affect activity towards some substrates, but not towards phenyl acetate. Gene ablation or over-expression of human PON1 in rodent models is associated with increased and decreased atherosclerosis susceptibility respectively. PON1 antioxidant activity is enhanced by apolipoprotein AI and lecithin:cholesterol acyl transferase and diminished by apolipoprotein AII, serum amyloid A, and myeloperoxidase. PON1 loses this activity when separated from its lipid environment. Information about its structure has been obtained from water soluble mutants created by directed evolution. Such recombinant PON1 may, however, lose the capacity to hydrolyse non-polar substrates. Whilst nutrition and pre-existing lipid modifying drugs can influence PON1 activity there is a cogent need for more specific PON1-raising medication to be developed.

Paraoxonase gene polymorphisms: Understanding the biochemical and genetic basis of coronary artery disease

Objectives

Serum paraoxonase (PON) is a glycoprotein with antioxidant and anti-atherosclerotic activities. The Q192R and L55M gene polymorphisms of PON have been implicated as risk factors for coronary artery disease (CAD) but have not been extensively explored in South Indians. We aimed to assess the Q192R and L55M genetic polymorphisms of the PON1 gene in participants with CAD, including genotypes and allele frequencies for PON1 gene polymorphism.

Methods

This prospective case-control study involved 20 participants in each group. Patients with angiographically demonstrated CAD were included in the case group. PON1 activity was measured, and PON gene polymorphism was determined. Serum PON was quantitatively analyzed with a RayBio® Human PON1 ELISA kit. Chi square tests were used to assess the association of the genotypes with sex and any comorbidities in cases and controls. A p value ≤ 0.05 was considered significant.

Results

Mutant type L55M polymorphism was observed in 50% of patients, whereas wild type Q192R polymorphism was observed in 42.5% of the participants. The mean PON values between groups did not significantly differ, whereas PON U/L was significantly (p = 0.001) lower in the case group. The L55M polymorphism did not significantly differ between the case and the control groups (p = 0.213), whereas the Q192R polymorphism was statistically significant in cases compared with controls (p ≤ 0.001).

Conclusion

Low plasma PON1 and HDL levels, and higher LDL, total cholesterol and triglyceride levels were observed in patients with CAD. More patients with CAD than healthy individuals had Q192R polymorphism.

The Hydrolysis Rate of Paraoxonase-1 Q and R Isoenzymes: An In Silico Study Based on In Vitro Data

Human serum paraoxonase-1 (PON1) is an important hydrolase-type enzyme found in numerous tissues. Notably, it can exist in two isozyme-forms, Q and R, that exhibit different activities. This study presents an in silico (QSAR, Docking, MD and QM/MM) study of a set of compounds on the activity towards the PON1 isoenzymes (QPON1 and RPON1). Different rates of reaction for the Q and R isoenzymes were analyzed by modelling the effect of Q192R mutation on active sites. It was concluded that the Q192R mutation is not even close to the active site, while it is still changing the geometry of it. Using the combined genetic algorithm with multiple linear regression (GA-MLR) technique, several QSAR models were developed and relative activity rates of the isozymes of PON1 explained. From these, two QSAR models were selected, one each for the QPON1 and RPON1. Best selected models are four-variable MLR models for both Q and R isozymes with squared correlation coefficient R² values of 0.87 and 0.83, respectively. In addition, the applicability domain of the models was analyzed based on the Williams plot. The results were discussed in the light of the main factors that influence the hydrolysis activity of the PON1 isozymes.

Paraoxonase 1 gene polymorphisms in lipid oxidation and atherosclerosis development

Paraoxonase 1 (PON1) is calcium-dependent aryldialkylphosphatase, thought to possess; anti-oxidant, anti-adhesion, anti-inflammatory, anti-thrombosis and anti-apoptosis effects, as well as lipid-modifying properties. Numerous clinical studies have shown associations between different PON1 polymorphisms and different cardiovascular pathologies. The rs622 (c.575A > G) and the rs854560 (c.163A > T) are the most studied PON1 SNPs in the coding region, with rs705381 (− 162A/G), rs854572 (− 909G/C) and rs705379 (− 108C/T) being the most studied SNPs in the regulatory PON1 gene region. The three major PON1 activities are aryldialkylphosphatase, arylesterase and lactonase activity. The different SNPs affect PON1 serum concentrations and enzyme activity, thus leading to pro-/anti-atherogenic effects. In that setting, it is very difficult to establish as to whether the genotype or phenotype of PON1 is primarily associated with cardiovascular risk. Given the current scientific evidence, PON1 genotyping might be reasonable in patients with high and very high cardiovascular risk.

Paraoxonase-1 Facilitates PRRSV Replication by Interacting with Viral Nonstructural Protein-9 and Inhibiting Type I Interferon Pathway

Paraoxonase-1 (PON1), an esterase with specifically paraoxonase activity, has been proven to be involved in inflammation and infection. Porcine reproductive and respiratory syndrome virus (PRRSV) is still a major concern in pigs and causes severe economic losses to the swine industry worldwide. In this study, the role of PON1 was investigated in porcine alveolar macrophages (PAMs) during PRRSV infection. The results showed that PRRSV replication downregulated PON1, and the knockdown of PON1 significantly decreased PRRSV replication. Similarly, PON1 overexpression could enhance PRRSV replication. Interestingly, we observed that PON1 interacted with PRRSV nonstructural protein 9 (Nsp9), the RNA-dependent RNA polymerase, and the knockdown of PON1 lowered the RNA binding ability of Nsp9, suggesting that PON1 can facilitate Nsp9 function in viral replication. In addition, the knockdown of PON1 expression led to the amplification of type I interferon (IFN) genes and vice versa. In summary, our data demonstrate that PON1 facilitates PRRSV replication by interacting with Nsp9 and inhibiting the type I IFN signaling pathway. Hence, PON1 may be an additional component of the anti-PRRSV defenses.

The Relationship between Cancer and Paraoxonase 1

Extensive research has been carried out to understand and elucidate the mechanisms of paraoxonase 1 (PON1) in the development of diseases including cancer, cardiovascular diseases, neurological diseases, and inflammatory diseases. This review focuses on the relationship between PON1 and cancer. The data suggest that PON1, oxidative stress, chronic inflammation, and cancer are closely linked. Certainly, the gene expression of PON1 will remain challenging to study. Therefore, targeting PON1, redox-sensitive pathways, and transcription factors promise prevention and therapy in the development of several diseases, including cancer.

Paraoxonase 1 (PON1) L55M and Q192R polymorphisms are not associated with chronic kidney disease in Thai individuals with type 2 diabetes

BACKGROUND

Decreased paraoxonase 1 (PON1) activity and PON1 polymorphisms have been found to be associated with chronic kidney disease (CKD) in type 2 diabetes mellitus (T2DM).

OBJECTIVE

This study aimed to investigate the association of the PON1 L55M and Q192R polymorphisms with CKD in T2DM, as well as their relationship with PON1 activity.

METHODS

A total of 166 T2DM patients, including 83 CKD patients and 83 non-CKD patients, were recruited. Biochemical parameters and paraoxonase (PONase) and arylesterase (AREase) activities were measured. The PON1 L55M and Q192R polymorphisms were analysed by a polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method. Data were analysed using the chi-square test, Student's t-test and logistic regression analysis.

RESULTS

Total cholesterol, TGs, LDL-C and Cr were significantly higher in CKD patients than in non-CKD patients. In contrast, the estimated glomerular filtration rate (eGFR) and AREase activity were significantly lower in CKD patients than in non-CKD patients (P < .05). The genotype and allele frequencies of the PON1 L55M and Q192R polymorphisms were not significantly different between CKD and non-CKD patients. Multivariate logistic regression analysis showed no association between the PON1 L55M and Q192R polymorphisms and CKD in T2DM. In addition, among all patients, patients with the PON1 LM genotype had significantly lower PONase activity than those with the LL genotype (P < .05). Among all patients, CKD patients and non-CKD patients, those with the PON1 RR genotype had significantly higher PONase activity but lower AREase activity than patients with the QR and QQ genotypes (P < .05).

CONCLUSIONS

PON1 activity was influenced by the PON1 L55M and Q192R polymorphisms. However, the PON1 L55M and Q192R polymorphisms may not be considered genetic biomarkers for CKD in T2DM.

Myeloperoxidase-induced modification of HDL by isolevuglandins inhibits paraoxonase-1 activity

Reduced activity of paraoxonase 1 (PON1), a high-density lipoprotein (HDL)-associated enzyme, has been implicated in the development of atherosclerosis. Post-translational modifications of PON1 may represent important mechanisms leading to reduced PON1 activity. Under atherosclerotic conditions, myeloperoxidase (MPO) is known to associate with HDL. MPO generates the oxidants hypochlorous acid and nitrogen dioxide, which can lead to post-translational modification of PON1, including tyrosine modifications that inhibit PON1 activity. Nitrogen dioxide also drives lipid peroxidation, leading to the formation of reactive lipid dicarbonyls such as malondialdehyde and isolevuglandins, which modify HDL and could inhibit PON1 activity. Because isolevuglandins are more reactive than malondialdehyde, we used in vitro models containing HDL, PON1, and MPO to test the hypothesis that IsoLG formation by MPO and its subsequent modification of HDL contributes to MPO-mediated reductions in PON1 activity. Incubation of MPO with HDL led to modification of HDL proteins, including PON1, by IsoLG. Incubation of HDL with IsoLG reduced PON1 lactonase and antiperoxidation activities. IsoLG modification of recombinant PON1 markedly inhibited its activity, while irreversible IsoLG modification of HDL before adding recombinant PON1 only slightly inhibited the ability of HDL to enhance the catalytic activity of recombinant PON1. Together, these studies support the notion that association of MPO with HDL leads to lower PON1 activity in part via IsoLG-mediated modification of PON1, so that IsoLG modification of PON1 could contribute to increased risk for atherosclerosis, and blocking this modification might prove beneficial to reduce atherosclerosis.

The Role of Paraoxonase 1 (PON1) Gene Polymorphisms in Coronary Artery Disease: A Systematic Review and Meta-Analysis

Although many studies have investigated the association of paraoxonase 1 (PON1) polymorphisms with coronary artery disease (CAD). However, the outcomes were not consistent and remain uncertain. Therefore, it is the need of the hour to analyze the available literature and evaluate the association of PON1 polymorphisms with the CAD. All the relevant studies published in the English language from January 1, 2000, up to September 20, 2020, were identified by searching through various electronic databases. The two researchers independently extracted the information. The data were analyzed by using the MetaGenyo program. The pooled odds ratio was used to find the associations between CAD and PON1 polymorphisms. In the final analysis, we include 10 studies regarding the association of PON1 polymorphisms (rs662 and rs854560) with CAD. Overall, the Q192R polymorphism increased the risk of CAD in the tested genetic models including the homozygote model: OR 1.35, CI 1.02-1.79; allelic model: OR 1.16, CI 1.00-1.33; dominant model: OR 1.25, CI 1.03-1.52. The L55M polymorphism does not significantly associated with CAD in all the tested genetic models including the homozygote model: OR 1.00 CI, 0.64-1.56; allelic model: OR 1.02, 95% CI 0.84-1.23; dominant model: OR 1.08, CI 0.89-1.31. Further analysis showed no publication bias exists in meta-analysis. Our findings suggested that rs662 in the coding region was significantly associated with the CAD however, rs854560 has no significant association with the disease. Nevertheless, in future, there is a need for more studies with a larger sample size which may provide a more definite conclusion.Study Registration: PROSPERO registration number CRD42020202278.

Effect of gene-environment interaction (arsenic exposure - PON1 Q192R polymorphism) on cardiovascular disease biomarkers in Mexican population

Cardiovascular diseases (CVDs) are the primary cause of death worldwide. However, little is known about how the interaction between risk factors affects CVDs. Therefore, the aim of this study was to evaluate the effect of the gene-environment interaction (arsenic exposure x PON1 Q192R polymorphism) on serum levels of CVDs biomarkers in Mexican women. Urinary arsenic levels (UAs) ranged from 5.50-145 μg/g creatinine. The allele frequency was 0.38 and 0.62 for the Q and R alleles, respectively. Moreover, significant associations (p<0.05) were detected between UAs and CVDs biomarkers (ADMA, FABP4, and miR-155). Comparable data were found when CVDs biomarkers were evaluated through PON1 genotype, significant (p<0.05) higher serum concentrations of CVDs biomarkers were identified in R allele carriers compared to levels found in Q allele carriers. Besides, a gene-environment interaction was documented. The results of this study we believe should be of significant interest to regulatory authorities worldwide.

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

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