Mice lacking serum paraoxonase are susceptible to organophosphate toxicity and atherosclerosis

Exploring the Association Between Systemic Lupus Erythematosus and High-Density Lipoproteins: A Systematic Review and Meta-Analysis

OBJECTIVE

Systemic lupus erythematosus (SLE) is an autoimmune disease with inflammation as a critical feature. Recently, high-density lipoprotein cholesterol (HDLc) have been evidenced to have anti-inflammatory effects, suggesting a potential link between HDL and SLE that needs to be thoroughly studied. The aim was to explore the association between SLE and HDLc through a systematic review with meta-analysis.

METHODS

A systematic review with meta-analysis was conducted to assess mean differences in HDL levels between patients with SLE and healthy controls. Both qualitative and quantitative syntheses were performed, including an assessment of heterogeneity using I2, a publication bias evaluation, a methodologic quality assessment, and a forest plot under a random effects model. Subgroup analyses were conducted based on disease activity and the report of corticosteroid dosage.

RESULTS

A total of 53 studies were included in the qualitative synthesis, and 35 studies were included in the quantitative synthesis, comprising 3,002 patients with SLE and 2,123 healthy controls. Mean HDL levels were found to be lower in patients with SLE as follows: in the meta-analysis including all articles -6.55 (95% confidence interval [CI] -8.77 to -4.33); in patients with mild disease activity -5.46 (95% CI -8.26 to -2.65); in patients with moderate or severe disease activity -9.42 (95% CI -15.49 to -3.34); in patients using corticosteroids -5.32 (95% CI -10.35 to -0.29); and in studies with excellent methodologic quality -8.71 (95% CI -12.38 to -5.03).

CONCLUSION

HDL levels appear to be quantitatively altered in patients with SLE, suggesting a potential contribution to immune dysregulation, highlighting the importance of HDL in autoimmune diseases.

Dysfunctional HDL Diagnostic Metrics for Cardiovascular Disease Risk Stratification: Are we Ready to Implement in Clinics?

Epidemiological studies have revealed that patients with higher levels of high-density lipoprotein cholesterol (HDL-C) were more resistant to cardiovascular diseases (CVD), and yet targeting HDL for CVD prevention, risk assessment, and pharmacological management has not proven to be very effective. The mechanistic investigations have demonstrated that HDL exerts anti-atherogenic functions via mediating reverse cholesterol transport, antioxidant action, anti-inflammatory activity, and anti-thrombotic activity. Contrary to expectations, however, adverse cardiovascular events were reported in clinical trials of drugs that raised HDL levels. This has sparked a debate between HDL quantity and quality. Patients with atherosclerotic CVD are associated with dysfunctional HDL, and the degree of HDL dysfunction is correlated with the severity of the disease, independent of HDL-C levels. This growing body of evidence has underscored the need for integrating HDL functional assays in clinical practice for CVD risk management. Because HDL exerts diverse athero-protective functions, there is no single method for capturing HDL functionality. This review critically evaluates the various techniques currently being used for monitoring HDL functionality and discusses key structural changes in HDL indicative of dysfunctional HDL and the technical challenges that need to be addressed to enable the integration of HDL function-based metrics in clinical practice for CVD risk estimation and the development of newer therapies targeting HDL function.

The Association of the Cholesterol Efflux Capacity with the Paraoxonase 1 Q192R Genotype and the Paraoxonase Activity

AIMS

Paraoxonase 1 (PON1) binds to high-density lipoprotein (HDL) and protects against atherosclerosis. However, the relationship between functional PON1 Q192R polymorphism, which is associated with the hydrolysis of paraoxon (POXase activity) and atherosclerotic cardiovascular disease (ASCVD), remains controversial. As the effect of PON1 Q192R polymorphism on the HDL function is unclear, we investigated the relationship between this polymorphism and the cholesterol efflux capacity (CEC), one of the biological functions of HDL, in association with the PON1 activity.

METHODS

The relationship between PON1 Q192R polymorphisms and CEC was investigated retrospectively in 150 subjects without ASCVD (50 with the PON1 Q/Q genotype, 50 with the Q/R genotype, and 50 with the R/R genotype) who participated in a health screening program. The POXase and arylesterase (AREase: hydrolysis of aromatic esters) activities were used as measures of the PON1 activity.

RESULTS

The AREase activity was positively correlated with CEC independent of the HDL cholesterol levels. When stratified by the PON1 Q192R genotype, the POXase activity was also positively correlated with CEC independent of HDL cholesterol. PON1 Q192R R/R genotype carriers had a lower CEC than Q/Q or Q/R genotype carriers, despite having a higher POXase activity. Moreover, in a multiple regression analysis, the PON1 Q192R genotype was associated with the degree of CEC, independent of the HDL cholesterol and POXase activity.

CONCLUSIONS

The PON1 Q192R R allele is associated with reduced CEC in Japanese people without ASCVD. Further studies on the impact of this association on the severity of atherosclerosis and ASCVD development are thus called for.

Discovery of a novel homocysteine thiolactone hydrolase and the catalytic activity of its natural variants

Homocysteine thiolactone (HTL), a toxic metabolite of homocysteine (Hcy) in hyperhomocysteinemia (HHcy), is known to modify protein structure and function, leading to protein damage through formation of N-Hcy-protein. HTL has been highly linked to HHcy-associated cardiovascular and neurodegenerative diseases. The protective role of HTL hydrolases against HTL-associated vascular toxicity and neurotoxicity have been reported. Although several endogeneous enzymes capable of hydrolyzing HTL have been identified, the primary enzyme responsible for its metabolism remains unclear. In this study, three human carboxylesterases were screened to explore new HTL hydrolase and human carboxylesterase 1 (hCES1) demonstrates the highest catalytic activity against HTL. Given the abundance of hCES1 in the liver and the clinical significance of its single-nucleotide polymorphisms (SNPs), six common hCES1 nonsynonymous coding SNP (nsSNPs) variants were examined and characterized for their kinetic parameters. Variants E220G and G143E displayed 7.3-fold and 13.2-fold lower catalytic activities than its wild-type counterpart. In addition, the detailed catalytic mechanism of hCES1 for HTL hydrolysis was computational investigated and elucidated by Quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) method. The function of residues E220 and G143 in sustaining its hydrolytic activity of hCES1 was analyzed, and the calculated energy difference aligns well with experimental-derived results, supporting the validity of our computational insights. These findings provide insights into the potential protective role of hCES1 against HTL-associated toxicity, and warrant future studies on the possible association between specific genetic variants of hCES1 with impaired catalytic function and clinical susceptibility of HTL-associated cardiovascular and neurodegenerative diseases.

Paraoxonase 1: evolution of the enzyme and of its role in protecting against atherosclerosis

PURPOSE OF REVIEW

To review the discoveries which led to the concept that serum paraoxonase 1 (PON1) is inversely related to atherosclerotic cardiovascular disease (ASCVD) incidence, how this association came to be regarded as causal and how such a role might have evolved.

RECENT FINDINGS

Animal models suggest a causal link between PON1 present on HDL and atherosclerosis. Serum PON1 activity predicts ASCVD with a similar reliability to HDL cholesterol, but at the extremes of high and low HDL cholesterol, there is discordance with PON1 being potentially more accurate. The paraoxonase gene family has its origins in the earliest life forms. Its greatest hydrolytic activity is towards lactones and organophosphates, both of which can be generated in the natural environment. It is active towards a wide range of substrates and thus its conservation may have resulted from improved survival of species facing a variety of evolutionary challenges.

SUMMARY

Protection against ASCVD is likely to be the consequence of some promiscuous activity of PON1, but nonetheless has the potential for exploitation to improve risk prediction and prevention of ASCVD.

Improving consumer understanding of pesticide toxicity labels: experimental evidence

Consumers often inadvertently misperceive the health hazards associated with over-the-counter pesticides under the current textual labeling policy, potentially leading to improper use. We conducted an incentivized framed field experiment with eye tracking to evaluate the effectiveness of the current pesticide labels that convey risk using signal words (Caution, Warning, Danger) compared to two visually focused label alternatives: traffic light colors and skull intensity symbols. A total of 166 participants were randomly assigned to one of three label formats and asked to rank toxicity levels and make purchasing decisions within multiple price lists. Results show that signal words fail to adequately communicate toxicity levels. Specifically, participants' correct assessment of toxicity level dramatically improves from 54% under the existing signal word label to 95% under the traffic light and 83% under the skull intensity symbol labels. We also find that participants are more likely to choose the less toxic alternatives under the new labels, suggesting the current labeling system may affect choice and have unintended adverse effects on human health.

Homocysteine Thiolactone Detoxifying Enzymes and Alzheimer's Disease

Elevated levels of homocysteine (Hcy) and related metabolites are associated with Alzheimer's disease (AD). Severe hyperhomocysteinemia causes neurological deficits and worsens behavioral and biochemical traits associated with AD. Although Hcy is precluded from entering the Genetic Code by proofreading mechanisms of aminoacyl-tRNA synthetases, and thus is a non-protein amino acid, it can be attached to proteins via an N-homocysteinylation reaction mediated by Hcy-thiolactone. Because N-homocysteinylation is detrimental to a protein's function and biological integrity, Hcy-thiolactone-detoxifying enzymes-PON1, BLMH, BPHL-have evolved. This narrative review provides an account of the biological function of these enzymes and of the consequences of their impairments, leading to the phenotype characteristic of AD. Overall, accumulating evidence discussed in this review supports a hypothesis that Hcy-thiolactone contributes to neurodegeneration associated with a dysregulated Hcy metabolism.

Pon1 and Sult1a1 Polymorphisms and Breast Cancer Among Young Women in Brazil

Purpose: To investigate the association of genetic polymorphisms Gln192Arg and Leu55Met of Paraoxonase 1 (PON1) gene, and Arg213His of Sulfotransferase 1A1 (SUT1A1) gene with occurrence of breast cancer among young women living in Rio de Janeiro city. Methods: This is a hospital-based case-control study including 265 women aged 18-35 years, diagnosed with breast cancer at National Cancer Institute; and 277 controls in the same age group selected among women patients and companions of three general hospitals from Rio de Janeiro public health network. Polymorphisms genotyping was performed using the PCR-RFLP technique. Results: For PON1 gene, breast cancer women had a greater chance of being homozygote for Leu55Met polymorphism (ORadjusted = 1.42, 95% CI= 0.67-3.00, recessive model) and a lower chance of having at least one allele of Gln192Arg polymorphism (ORadjusted = 0.75, 95% CI = 0.50-1.13, dominant model), but without statistical significance. Accordingly, frequency of the haplotype Met55/Arg192 was lower among breast cancer women, but no statistically significant association was observed (ORadjusted = 0.85; 95% CI = 0.48-1.51). SULT1A1 His/His genotype was significantly associated with a protective effect for breast cancer (OR adjusted = 0.51, 95% CI = 0.28-0.91, recessive model). Conclusion: Arg213His polymorphism of SUT1A1 gene showed a protective effect against breast cancer among Brazilian young women. More studies with different designs are needed to understand the role of PON1 and SULT1A1 polymorphisms in breast cancer development in young Brazilian women.

Applications of Microbial Organophosphate-Degrading Enzymes to Detoxification of Organophosphorous Compounds for Medical Countermeasures against Poisoning and Environmental Remediation

Mining of organophosphorous (OPs)-degrading bacterial enzymes in collections of known bacterial strains and in natural biotopes are important research fields that lead to the isolation of novel OP-degrading enzymes. Then, implementation of strategies and methods of protein engineering and nanobiotechnology allow large-scale production of enzymes, displaying improved catalytic properties for medical uses and protection of the environment. For medical applications, the enzyme formulations must be stable in the bloodstream and upon storage and not susceptible to induce iatrogenic effects. This, in particular, includes the nanoencapsulation of bioscavengers of bacterial origin. In the application field of bioremediation, these enzymes play a crucial role in environmental cleanup by initiating the degradation of OPs, such as pesticides, in contaminated environments. In microbial cell configuration, these enzymes can break down chemical bonds of OPs and usually convert them into less toxic metabolites through a biotransformation process or contribute to their complete mineralization. In their purified state, they exhibit higher pollutant degradation efficiencies and the ability to operate under different environmental conditions. Thus, this review provides a clear overview of the current knowledge about applications of OP-reacting enzymes. It presents research works focusing on the use of these enzymes in various bioremediation strategies to mitigate environmental pollution and in medicine as alternative therapeutic means against OP poisoning.

High-density lipoprotein in diabetes: Structural and functional relevance

Low levels of high-density lipoprotein-cholesterol (HDL-C) is considered a major cardiovascular risk factor. However, recent studies have suggested a more U-shaped association between HDL-C and cardiovascular disease. It has been shown that the cardioprotective effect of HDL is related to the functions of HDL particles rather than their cholesterol content. HDL particles are highly heterogeneous and have multiple functions relevant to cardiometabolic conditions including cholesterol efflux capacity, anti-oxidative, anti-inflammatory, and vasoactive properties. There are quantitative and qualitative changes in HDL as well as functional abnormalities in both type 1 and type 2 diabetes. Non-enzymatic glycation, carbamylation, oxidative stress, and systemic inflammation can modify the HDL composition and therefore the functions, especially in situations of poor glycemic control. Studies of HDL proteomics and lipidomics have provided further insights into the structure-function relationship of HDL in diabetes. Interestingly, HDL also has a pleiotropic anti-diabetic effect, improving glycemic control through improvement in insulin sensitivity and β-cell function. Given the important role of HDL in cardiometabolic health, HDL-based therapeutics are being developed to enhance HDL functions rather than to increase HDL-C levels. Among these, recombinant HDL and small synthetic apolipoprotein A-I mimetic peptides may hold promise for preventing and treating diabetes and cardiovascular disease.

Biological markers of high risk of thrombotic recurrence in patients with antiphospholipid syndrome: A literature review

OBJECTIVES

This review aims to identify biological markers associated with the risk of recurrence of thrombotic and/or obstetric events in patients with antiphospholipid syndrome (APS).

METHODS

A comprehensive review of literature was conducted to evaluate established and potential novel biological markers associated with thrombosis in APS. To this end, a PubMed literature search was conducted for the last twenty years using the following keywords or their combinations: thrombotic risk, recurrence of thrombosis, risk stratification, severity, predictive value.

RESULTS

Previous studies showed that multiple aPL positivity correlates with an increased risk of thrombosis in APS. Moreover, the analysis of N-glycosylation of antiphospholipid antibodies (aPL) revealed that low levels of IgG sialylation, fucosylation or galactosylation increases the pro-inflammatory activity of aPL, predisposing to thrombosis. In addition, quantification of neutrophil extracellular traps (NETs) and antibodies directed against NETs (anti-NETs) in serum demonstrates promising prognostic utility in assessing APS severity. Oxidative stress plays a role in the pathogenicity of APS and paraoxonase 1 (PON1) activity emerges as a promising biomarker of thrombotic risk in APS. Furthermore, identification of novel antigenic targets involved in the pathophysiology of APS, such as lysobisphosphatidic acid (LBPA), had led to the discovery of unconventional aPL, antibodies directed against the LBPA (aLBPA), whose clinical value could make it possible to identify APS patients at high risk of thrombotic recurrence.

CONCLUSION

The immunological profile of aPL, N-glycosylation of aPL, quantification of NETs and anti-NETs, analysis of biomarkers of oxidative stress and the discovery of aLBPA offer potential prognostic tools for risk stratification in APS patients.

Nrf2 Signaling Pathway as a Key to Treatment for Diabetic Dyslipidemia and Atherosclerosis

Diabetes mellitus (DM) is a chronic endocrine disorder that affects more than 20 million people in the United States. DM-related complications affect multiple organ systems and are a significant cause of morbidity and mortality among people with DM. Of the numerous acute and chronic complications, atherosclerosis due to diabetic dyslipidemia is a condition that can lead to many life-threatening diseases, such as stroke, coronary artery disease, and myocardial infarction. The nuclear erythroid 2-related factor 2 (Nrf2) signaling pathway is an emerging antioxidative pathway and a promising target for the treatment of DM and its complications. This review aims to explore the Nrf2 pathway's role in combating diabetic dyslipidemia. We will explore risk factors for diabetic dyslipidemia at a cellular level and aim to elucidate how the Nrf2 pathway becomes a potential therapeutic target for DM-related atherosclerosis.

Organophosphate toxicity patterns: A new approach for assessing organophosphate neurotoxicity

Organophosphorus compounds or organophosphates (OPs) are widely used as flame retardants, plasticizers, lubricants and pesticides. This contributes to their ubiquitous presence in the environment and to the risk of human exposure. The persistence of OPs and their bioaccumulative characteristics raise serious concerns regarding environmental and human health impacts. To address the need for safer OPs, this study uses a New Approach Method (NAM) to analyze the neurotoxicity pattern of 42 OPs. The NAM consists of a 4-step process that combines computational modeling with in vitro and in vivo experimental studies. Using spherical harmonic-based cluster analysis, the OPs were grouped into four main clusters. Experimental data and quantitative structure-activity relationships (QSARs) analysis were used in conjunction to provide information on the neurotoxicity profile of each group. Results showed that one of the identified clusters had a favorable safety profile, which may help identify safer OPs for industrial applications. In addition, the 3D-computational analysis of each cluster was used to identify meta-molecules with specific 3D features. Toxicity was found to correspond to the level of phosphate surface accessibility. Substances with conformations that minimize phosphate surface accessibility caused less neurotoxic effect. This multi-assay NAM could be used as a guide for the classification of OP toxicity, helping to minimize the health and environmental impacts of OPs, and providing rapid support to the chemical regulators, whilst reducing reliance on animal testing.

PON1 has palmitoyl-protein thioesterase (PPT) activity, and can affect the presence of SR-B1 on the endothelial cell membrane

The high-density lipoprotein (HDL)-associated enzyme paraoxonase 1 (PON1) is expressed almost exclusively in the liver and is then transported by HDL to the peripheral tissues. The lipophilic nature of PON1 enables its easy exchange between the lipoprotein and cell membranes in a process that is dependent on the HDL receptor scavenger receptor class B, type 1 (SR-B1). In endothelial cells, PON1 binding to the cell membrane leads to its internalization by endocytosis and subsequent lysosomal degradation. PON1 is a "promiscuous" enzyme with unusually broad substrate specificity in vitro, but its actual function and substrate are still unknown. The enzyme requires a lipid environment and becomes completely inactive upon delipidation. However, when PON1 binds HDL, its active site faces the lipoprotein's core and is inaccessible to external substrates. Hence, the HDL-bound PON1 is inactive toward substrates outside the particle's lipid core and is rapidly degraded and becomes inactive upon internalization. Consequently, the enzyme is only active in the cell membrane during its transit from HDL to the cytoplasm. To assign a function to PON1, we investigated whether it is a palmitoyl-protein thioesterase (PPT) that can hydrolyze the palmitoyl moieties of membrane proteins involved in HDL and cholesterol transport, such as SR-B1, ABCA1, or their neighboring caveola proteins to facilitate the release of HDL or trigger its endocytosis. This study shows that PON1 can hydrolyze palmitoyl-cysteine thioester bonds in vitro, has direct or indirect PPT activity in vivo, and can significantly decrease the presence of SR-B1 in the endothelial membrane.

Modulation of the antioxidant enzyme paraoxonase-1 for protection against cardiovascular diseases

AIM

The enzyme paraoxonase 1 (PON1) bound to high-density lipoprotein has received special attention for its protective role against stress-mediated damage and use as a potential regulatory target in atherosclerosis and related vascular diseases.

DATA SYNTHESIS

We present an overview of the literature on PON1 activity and mRNA levels by investigating its modulation for clinical translations. Specifically, the expression of PON1 and its regulated activity can be modified in different ways with natural substances, drugs, and lifestyle factors thar affect the development of atherosclerosis.

CONCLUSIONS

The endothelial contribution of PON1 to overcome differences considering an individual's disease development risk is supported by polymorphism interaction data and the susceptibility to modify PON1 responses in chronic events composed by biological and environmental factors.

Apolipoprotein A1 and high-density lipoprotein limit low-density lipoprotein transcytosis by binding SR-B1

Atherosclerosis results from the deposition and oxidation of LDL and immune cell infiltration in the sub-arterial space leading to arterial occlusion. Studies have shown that transcytosis transports circulating LDL across endothelial cells lining blood vessels. LDL transcytosis is initiated by binding to either scavenger receptor B1 (SR-B1) or activin A receptor-like kinase 1 on the apical side of endothelial cells leading to its transit and release on the basolateral side. HDL is thought to partly protect individuals from atherosclerosis due to its ability to remove excess cholesterol and act as an antioxidant. Apolipoprotein A1 (APOA1), an HDL constituent, can bind to SR-B1, raising the possibility that APOA1/HDL can compete with LDL for SR-B1 binding, thereby limiting LDL deposition in the sub-arterial space. To examine this possibility, we used in vitro approaches to quantify the internalization and transcytosis of fluorescent LDL in coronary endothelial cells. Using microscale thermophoresis and affinity capture, we find that SR-B1 and APOA1 interact and that binding is enhanced when using the cardioprotective variant of APOA1 termed Milano (APOA1-Milano). In male mice, transiently increasing the levels of HDL reduced the acute deposition of fluorescently labeled LDL in the atheroprone inner curvature of the aorta. Reduced LDL deposition was also observed when increasing circulating wild-type APOA1 or the APOA1-Milano variant, with a more robust inhibition from the APOA1-Milano. The results suggest that HDL may limit SR-B1-mediated LDL transcytosis and deposition, adding to the mechanisms by which it can act as an atheroprotective particle.

Role of paraoxonase 3 in regulating ENaC-mediated Na+ transport in the distal nephron

Paraoxonase 3 (PON3) is expressed in the aldosterone-sensitive distal nephron, where filtered Na+ is reabsorbed mainly via the epithelial Na+ channel (ENaC) and Na+ -coupled co-transporters. We previously showed that PON3 negatively regulates ENaC through a chaperone mechanism. The present study aimed to determine the physiological role of PON3 in renal Na+ and K+ homeostasis. Pon3 knockout (KO) mice had higher amiloride-induced natriuresis and lower plasma [K+ ] at baseline. Single channel recordings in split-open tubules showed that the number of active channels per patch was significantly higher in KO mice, resulting in a higher channel activity in the absence of PON3. Although whole kidney abundance of ENaC subunits was not altered in Pon3 KOs, ENaC gamma subunit was more apically distributed within the connecting tubules and cortical collecting ducts of Pon3 KO kidneys. Additionally, small interfering RNA-mediated knockdown of PON3 in cultured mouse cortical collecting duct cells led to an increased surface abundance of ENaC gamma subunit. As a result of lower plasma [K+ ], sodium chloride co-transporter phosphorylation was enhanced in the KO kidneys, a phenotype that was corrected by a high K+ diet. Finally, PON3 expression was upregulated in mouse kidneys under dietary K+ restriction, potentially providing a mechanism to dampen ENaC activity and associated K+ secretion. Taken together, our results show that PON3 has a role in renal Na+ and K+ homeostasis through regulating ENaC functional expression in the distal nephron. KEY POINTS: Paraoxonase 3 (PON3) is expressed in the distal nephron of mouse kidneys and functions as a molecular chaperone to reduce epithelial Na+ channel (ENaC) expression and activity in heterologous expression systems. We examined the physiological role of PON3 in renal Na+ and K+ handling using a Pon3 knockout (KO) mouse model. At baseline, Pon3 KO mice had lower blood [K+ ], more functional ENaC in connecting tubules/cortical collecting ducts, higher amiloride-induced natriuresis, and enhanced sodium chloride co-transporter (NCC) phosphorylation. Upon challenge with a high K+ diet, Pon3 KO mice had normalized blood [K+ ] and -NCC phosphorylation but lower circulating aldosterone levels compared to their littermate controls. Kidney PON3 abundance was altered in mice under dietary K+ loading or K+ restriction, providing a potential mechanism for regulating ENaC functional expression and renal Na+ and K+ homeostasis in the distal nephron.

Paraoxonase-like APMAP maintains endoplasmic reticulum-associated lipid and lipoprotein homeostasis

Oxidative stress perturbs lipid homeostasis and contributes to metabolic diseases. Though ignored compared to mitochondrial oxidation, the endoplasmic reticulum (ER) generates reactive oxygen species requiring antioxidant quality control. Using multi-organismal profiling featuring Drosophila, zebrafish, and mammalian cells, here we characterize the paraoxonase-like APMAP as an ER-localized protein that promotes redox and lipid homeostasis and lipoprotein maturation. APMAP-depleted mammalian cells exhibit defective ER morphology, elevated ER and oxidative stress, lipid droplet accumulation, and perturbed ApoB-lipoprotein homeostasis. Critically, APMAP loss is rescued with chemical antioxidant NAC. Organismal APMAP depletion in Drosophila perturbs fat and lipoprotein homeostasis, and zebrafish display increased vascular ApoB-containing lipoproteins, particles that are atherogenic in mammals. Lipidomics reveals altered polyunsaturated phospholipids and increased ceramides upon APMAP loss, which perturbs ApoB-lipoprotein maturation. These ApoB-associated defects are rescued by inhibiting ceramide synthesis. Collectively, we propose APMAP is an ER-localized antioxidant that promotes lipid and lipoprotein homeostasis.

mTOR-dependent loss of PON1 secretion and antiphospholipid autoantibody production underlie autoimmunity-mediated cirrhosis in transaldolase deficiency

Transaldolase deficiency predisposes to chronic liver disease progressing from cirrhosis to hepatocellular carcinoma (HCC). Transition from cirrhosis to hepatocarcinogenesis depends on mitochondrial oxidative stress, as controlled by cytosolic aldose metabolism through the pentose phosphate pathway (PPP). Progression to HCC is critically dependent on NADPH depletion and polyol buildup by aldose reductase (AR), while this enzyme protects from carbon trapping in the PPP and growth restriction in TAL deficiency. Although AR inactivation blocked susceptibility to hepatocarcinogenesis, it enhanced growth restriction, carbon trapping in the non-oxidative branch of the PPP and failed to reverse the depletion of glucose 6-phosphate (G6P) and liver cirrhosis. Here, we show that inactivation of the TAL-AR axis results in metabolic stress characterized by reduced mitophagy, enhanced overall autophagy, activation of the mechanistic target of rapamycin (mTOR), diminished glycosylation and secretion of paraoxonase 1 (PON1), production of antiphospholipid autoantibodies (aPL), loss of CD161+ NK cells, and expansion of CD38+ Ito cells, which are responsive to treatment with rapamycin in vivo. The present study thus identifies glycosylation and secretion of PON1 and aPL production as mTOR-dependent regulatory checkpoints of autoimmunity underlying liver cirrhosis in TAL deficiency.

Can HDL cholesterol be replaced by paraoxonase 1 activity in the prediction of severe coronary artery disease in patients with type 2 diabetes?

BACKGROUND AND AIMS

Novel biomarkers are required to improve cardiovascular disease prediction in patients with type 2 diabetes (T2D) as a high-risk population. This study was conducted to examine whether coronary artery disease (CAD) risk assessment can be improved by substituting high-density lipoprotein (HDL)-bound paraoxonase 1 (PON1) activity for HDL cholesterol (HDL-C) concentration in patients with T2D.

METHODS AND RESULTS

In this study, we studied 139 patients with T2D (mean age 64.12 ± 8.17 years) who underwent coronary angiographic examination. The initial rate of substrate hydrolysis was spectrophotometrically assayed in kinetic mode for measuring PON1 activity. Receiver operating characteristic (ROC) graphs are created by plotting true positivity versus false positivity. In patients with HbA_1c ≥ 7%, PON1 (AUC = 0.7, p = 0.029) and nonHDL-C/PON1 (AUC = 0.75, p = 0.013) were significantly more capable of differentiating patients with CAD from those without CAD compared to HDL-C and nonHDL-C/HDL-C. Also, the predictive power of PON1 (AUC = 0.64, p = 0.029) and nonHDL-C/PON1 (AUC = 0.71, p = 0.004) were significantly higher in comparison with HDL-C and nonHDL-C/HDL-C for CAD characterization in patients aged ≥50 years. Moreover, PON1 and nonHDL-C/PON1 are associated with the incidence of CAD with an AUC of 0.7 (p = 0.026) and AUC of 0.64 (p = 0.087), respectively, among subjects with low HDL-C.

CONCLUSION

PON1 and the ratio of nonHDL-C/PON1 significantly improve the prediction of severe CAD in T2D patients and in patients with HbA_1c ≥ 7%, age ≥50 years, or low HDL-C. PON1 activity and lipid ratios using this enzyme may be valuable as substitutes of HDL-C for increasing clinical efficacies in cardiovascular risk assessment.

Low concentrations of medium-sized HDL particles predict incident CVD in chronic kidney disease patients

Patients with chronic kidney disease (CKD) are at high risk for CVD. However, traditional CVD risk factors cannot completely explain the increased risk. Altered HDL proteome is linked with incident CVD in CKD patients, but it is unclear whether other HDL metrics are associated with incident CVD in this population. In the current study, we analyzed samples from two independent prospective case-control cohorts of CKD patients, the Clinical Phenotyping and Resource Biobank Core (CPROBE) and the Chronic Renal Insufficiency Cohort (CRIC). We measured HDL particle sizes and concentrations (HDL-P) by calibrated ion mobility analysis and HDL cholesterol efflux capacity (CEC) by cAMP-stimulated J774 macrophages in 92 subjects from the CPROBE cohort (46 CVD and 46 controls) and in 91 subjects from the CRIC cohort (34 CVD and 57 controls). We tested associations of HDL metrics with incident CVD using logistic regression analysis. No significant associations were found for HDL-C or HDL-CEC in either cohort. Total HDL-P was only negatively associated with incident CVD in the CRIC cohort in unadjusted analysis. Among the six sized HDL subspecies, only medium-sized HDL-P was significantly and negatively associated with incident CVD in both cohorts after adjusting for clinical confounders and lipid risk factors with odds ratios (per 1-SD) of 0.45 (0.22-0.93, P = 0.032) and 0.42 (0.20-0.87, P = 0.019) for CPROBE and CRIC cohorts, respectively. Our observations indicate that medium-sized HDL-P-but not other-sized HDL-P or total HDL-P, HDL-C, or HDL-CEC-may be a prognostic cardiovascular risk marker in CKD.

Reduction of Paraoxonase Expression Followed by Inactivation across Independent Semiaquatic Mammals Suggests Stepwise Path to Pseudogenization

Convergent adaptation to the same environment by multiple lineages frequently involves rapid evolutionary change at the same genes, implicating these genes as important for environmental adaptation. Such adaptive molecular changes may yield either change or loss of protein function; loss of function can eliminate newly deleterious proteins or reduce energy necessary for protein production. We previously found a striking case of recurrent pseudogenization of the Paraoxonase 1 (Pon1) gene among aquatic mammal lineages-Pon1 became a pseudogene with genetic lesions, such as stop codons and frameshifts, at least four times independently in aquatic and semiaquatic mammals. Here, we assess the landscape and pace of pseudogenization by studying Pon1 sequences, expression levels, and enzymatic activity across four aquatic and semiaquatic mammal lineages: pinnipeds, cetaceans, otters, and beavers. We observe in beavers and pinnipeds an unexpected reduction in expression of Pon3, a paralog with similar expression patterns but different substrate preferences. Ultimately, in all lineages with aquatic/semiaquatic members, we find that preceding any coding-level pseudogenization events in Pon1, there is a drastic decrease in expression, followed by relaxed selection, thus allowing accumulation of disrupting mutations. The recurrent loss of Pon1 function in aquatic/semiaquatic lineages is consistent with a benefit to Pon1 functional loss in aquatic environments. Accordingly, we examine diving and dietary traits across pinniped species as potential driving forces of Pon1 functional loss. We find that loss is best associated with diving activity and likely results from changes in selective pressures associated with hypoxia and hypoxia-induced inflammation.

Proteomic Exploration of Paraoxonase 1 Function in Health and Disease

High-density lipoprotein (HDL) exhibits cardio- and neuro-protective properties, which are thought to be promoted by paraoxonase 1 (PON1), a hydrolytic enzyme associated with an HDL subfraction also enriched with an anticoagulant protein (PROS1) and amyloid beta-transport protein clusterin (CLU, APOJ). Reduced levels of PON1 activity, characterized biochemically by elevated levels of homocysteine (Hcy)-thiolactone, oxidized lipids, and proteins modified by these metabolites in humans and mice, are associated with pathological abnormalities affecting the cardiovascular system (atherothrombosis) and the central nervous system (cognitive impairment, Alzheimer's disease). The molecular bases of these abnormalities have been largely unknown. Proteomic and metabolic studies over the past decade have significantly contributed to our understanding of PON1 function and the mechanisms by which PON1 deficiency can lead to disease. Recent studies discussed in this review highlight the involvement of dysregulated proteostasis in the pro-oxidative, pro-atherothrombotic, and pro-amyloidogenic phenotypes associated with low PON1 activity.

Depletion of Paraoxonase 1 (Pon1) Dysregulates mTOR, Autophagy, and Accelerates Amyloid Beta Accumulation in Mice

Paraoxonase 1 (PON1), a homocysteine (Hcy)-thiolactone detoxifying enzyme, has been associated with Alzheimer's disease (AD), suggesting that PON1 plays an important protective role in the brain. To study the involvement of PON1 in the development of AD and to elucidate the mechanism involved, we generated a new mouse model of AD, the Pon1-/-xFAD mouse, and examined how Pon1 depletion affects mTOR signaling, autophagy, and amyloid beta (Aβ) accumulation. To elucidate the mechanism involved, we examined these processes in N2a-APPswe cells. We found that Pon1 depletion significantly downregulated Phf8 and upregulated H4K20me1; mTOR, phospho-mTOR, and App were upregulated while autophagy markers Bcln1, Atg5, and Atg7 were downregulated at the protein and mRNA levels in the brains of Pon1─/─5xFAD vs. Pon1+/+5xFAD mice. Pon1 depletion in N2a-APPswe cells by RNA interference led to downregulation of Phf8 and upregulation of mTOR due to increased H4K20me1-mTOR promoter binding. This led to autophagy downregulation and significantly increased APP and Aβ levels. Phf8 depletion by RNA interference or treatments with Hcy-thiolactone or N-Hcy-protein metabolites similarly increased Aβ levels in N2a-APPswe cells. Taken together, our findings define a neuroprotective mechanism by which Pon1 prevents Aβ generation.

Modulatory Effect of Lifestyle-Related, Environmental and Genetic Factors on Paraoxonase-1 Activity: A Review

Paraoxonase-1 (PON1) is a calcium-dependent, HDL-bound serum hydrolase active toward a wide variety of substrates. PON1 displays three types of activities, among which lactonase, paraoxonase, arylesterase and phosphotriesterase can be distinguished. Not only is this enzyme a major organophosphate compound detoxifier, but it is also an important constituent of the cellular antioxidant system and has anti-inflammatory and antiatherogenic functions. The concentration and activity of PON1 is highly variable among individuals, and these differences can be both of genetic origin and be a subject of epigenetic regulation. Owing to the fact that, in recent decades, the exposure of humans to an increasing number of different xenobiotics has been continuously rising, the issues concerning the role and activity of PON1 shall be reconsidered with particular attention to growing pharmaceuticals intake, dietary habits and environmental awareness. In the following manuscript, the current state of knowledge concerning the influence of certain modifiable and unmodifiable factors, including smoking, alcohol intake, gender, age and genotype variation on PON1 activity, along with pathways through which these could interfere with the enzyme's protective functions, is presented and discussed. Since exposure to certain xenobiotics plays a key role in PON1 activity, the influence of organophosphates, heavy metals and several pharmaceutical agents is also specified.

Interactome of Paraoxonase PON2 Reveals New Pathways for Tumor Growth Regulation

The interactome of paraoxonase-2 encoded by the PON2 gene was investigated. A cDNA library was screened using a yeast two-hybrid system to search for new proteins interacting with human PON2. Analysis of the identified candidates, along with previously published data on interactors obtained by other methods, indicates the presence of a significant number of indirect interactions between PON2 and EGFR and, consequently, possible regulation of tumor growth with mutant EGFR involving PON2.

HDL Functions-Current Status and Future Perspectives

Cardiovascular disease (CVD) is the leading cause of death in Western countries. A low HDL-C is associated with the development of CVD. However, recent epidemiology studies have shown U-shaped curves between HDL-C and CVD mortality, with paradoxically increased CVD mortality in patients with extremely high HDL-C levels. Furthermore, HDL-C raising therapy using nicotinic acids or CETP inhibitors mostly failed to reduce CVD events. Based on this background, HDL functions rather than HDL-C could be a novel biomarker; research on the clinical utility of HDL functionality is ongoing. In this review, we summarize the current status of HDL functions and their future perspectives from the findings of basic research and clinical trials.

Mediation roles of neutrophils and high-density lipoprotein (HDL) on the relationship between HLA-DQB1 and rosacea

BACKGROUND

Though the previous genome-wide association studies found the association between HLA alleles and rosacea in the European populations, the data is lacking among the Asians. Moreover, neutrophils are important in the immune-related mechanism of rosacea, and dyslipidemia is closely related to rosacea. We aimed to explore the association between HLA genes and rosacea in Chinese rosacea patients, as well as the mediation effect of neutrophils, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) on the relationship between HLA genes and rosacea.

METHODS

A total of 249 rosacea and 150 controls were ranked by the international investigator global rosacea severity scores. HLA genes, neutrophils, HDL, and LDL were detected. And their mediation effects on the relationship between HLA and rosacea risk or severity were analysed.

RESULTS

HLA-DQB1*03:03 allele (OR = 41.89, 95% CI: 9.80 ∼ 179.09, p = 4.7*10-7), HLA-DQB1*04:02 allele (OR = 0.16, 95% CI: 0.03 ∼ 0.81, p = 0.026) and HLA-DQB1*03:03/05:02 genotype (OR = 5.57, 95% CI: 1.13 ∼ 27.52, p = 0.0351) were significantly associated with rosacea. Moreover, HLA-DQB1*03:03 allele (b = 1.434, SE = 0.217, p = 2.0*10-10), HLA-DQB1*05:01 allele (b = 0.894, SE = 0.33520, p = 0.008) and HLA-DQB1*03:03/06:01 genotype (b = 0.998, SE = 0.472, p = 0.040) were positively associated with rosacea severity. Furthermore, we found both neutrophils and HDL, instead of LDL, have mediation effects on the relationship between HLA-DQB1*03:03 and risk or severity of rosacea.

CONCLUSIONS

We discovered novel susceptible HLA alleles for rosacea in the Chinese population, and disclosed the mediation effect of neutrophils and HDL on the relationship between HLA-DQB1 and rosacea, implying a possible correlation between rosacea and inflammatory or metabolic factors, providing hints for future studies in the mechanism of rosacea. Key messagesHLA-DQB1*03:03 allele, HLA-DQB1*04:02 allele and HLA-DQB1*03:03/05:02 genotype were significantly associated with rosacea.HLA-DQB1*03:03 allele, HLA-DQB1*05:01 allele and HLA-DQB1*03:03/06:01 genotype were positively associated with rosacea severity.Neutrophils and HDL have mediation effects on the relationship between HLA-DQB1*03:03 and risk or severity of rosacea.

Association between Paraoxonase/Arylesterase Activity of Serum PON-1 Enzyme and Rheumatoid Arthritis: A Systematic Review and Meta-Analysis

Background: A decrease in serum paraoxonase (PON-1) and arylesterase (ARE) activity has been reported in rheumatoid arthritis (RA) patients and linked to chronic inflammation and impaired antioxidant defense. Methods: A systematic review and meta-analysis were performed to critically appraise the current evidence on plasma/serum concentrations of PON-1 and ARE activity in RA patients and healthy controls. The Web of Science, PubMed, Scopus, and Google Scholar databases were searched from inception to November 2021. We used random-effects meta-analysis. The risk of bias was estimated using the Joanna Briggs Institute Critical Appraisal Checklist tool. The certainty of the evidence was assessed with GRADE. The study complied with the PRISMA statements and was registered in PROSPERO (CRD42022345380). Results: Seventeen studies reported PON-1 activity (1144 RA patients, 797 controls) and ten reported ARE activity (1367 RA patients, 1037 controls). RA patients had significantly lower PON-1 (SMD = −1.32, 95% CI −1.94 to −0.70; p < 0.001) and ARE activity (SMD = −0.91, 95% CI −1.37 to −0.46; p < 0.001). There was substantial heterogeneity (PON, I2 97%; ARE, 95.7%, p < 0.001 for both). There was no publication bias. The pooled SMD values did not significantly change after sensitivity analysis. The certainty of the evidence was very low due to the observational nature of the studies and the large heterogeneity. Conclusion: Our meta-analysis has shown that both serum PON-1 and ARE activity are significantly lower in RA patients, suggesting a deficit in antioxidant defense mechanisms in this disease.

Cardioprotective Role for Paraoxonase-1 in Chronic Kidney Disease

Paraoxonase-1 (PON-1) is a hydrolytic enzyme associated with HDL, contributing to its anti-inflammatory, antioxidant, and anti-atherogenic properties. Deficiencies in PON-1 activity result in oxidative stress and detrimental clinical outcomes in the context of chronic kidney disease (CKD). However, it is unclear if a decrease in PON-1 activity is mechanistically linked to adverse cardiovascular events in CKD. We investigated the hypothesis that PON-1 is cardioprotective in a Dahl salt-sensitive model of hypertensive renal disease. Experiments were performed on control Dahl salt-sensitive rats (SSMcwi, hereafter designated SS-WT rats) and mutant PON-1 rats (SS-Pon1em1Mcwi, hereafter designated SS-PON-1 KO rats) generated using CRISPR gene editing technology. Age-matched 10-week-old SS and SS-PON-1 KO male rats were maintained on high-salt diets (8% NaCl) for five weeks to induce hypertensive renal disease. Echocardiography showed that SS-PON-1 KO rats but not SS-WT rats developed compensated left ventricular hypertrophy after only 4 weeks on the high-salt diet. RT-PCR analysis demonstrated a significant increase in the expression of genes linked to cardiac hypertrophy, inflammation, and fibrosis, as well as a significant decrease in genes essential to left ventricular function in SS-PON-1 KO rats compared to SS-WT rats. A histological examination also revealed a significant increase in cardiac fibrosis and immune cell infiltration in SS-PON-1 KO rats, consistent with their cardiac hypertrophy phenotype. Our data suggest that a loss of PON-1 in the salt-sensitive hypertensive model of CKD leads to increased cardiac inflammation and fibrosis as well as a molecular and functional cardiac phenotype consistent with compensated left ventricular hypertrophy.

Enhancement in the production of recombinant human paraoxonase 1 in Escherichia coli: A comprehensive approach of cellular engineering and optimization of protein folding process in vitro

Human paraoxonase 1(hPON1) belongs to the paraoxonase (PON) family. It is a calcium-dependent enzyme with a size of ∼43 kDa and is composed of 6 bladed beta-barrel structures with two calcium ions in its active site. In humans, it is synthesized in the liver and remains bound with the high-density lipoproteins (HDL) within the blood. It has immense potential to tackle the poisoning associated with the use of organophosphates (OPs) and their derivatives, such as nerve agents, due to role in their degradation. Therefore, hPON1 serves as a potential bio-scavenger that can be used as an antidote or as a surface decontaminating agent in OPs poisoning. However, present systems prove insufficient to produce it in sufficient quantity to make it industrially relevant. Here, our efforts involve producing it recombinantly in an E. coli system with enhanced expression levels by altering cellular and environmental conditions. This has been further improved by the development of in-vitro refolding process for the denatured recombinant hPON1 (rhPON1) protein. This methodology resulted in approximately 200 mg of the enzymatically functional protein from 1 l of E. coli culture. Proper refolding of rhPON1 was confirmed by comparing its enzymatic activity and conformation with serum purified hPON1.

A common genetic variation in paraoxonase 1 and risk of breast cancer: a literature review, meta-analysis, and in silico analysis

Paraoxonase 1 (PON1), an enzyme with multifactorial antioxidant activity, has a protective role against oxidative stress, which is supposed to contribute to the development of cancers including breast cancer. The aim of this study was to examine the correlation of PON1-L55M common genetic polymorphism with the risk of breast cancer in a meta-analysis approach which was followed by an in silico analysis. The eligible studies were collected from valid electronic databases such as Google Scholar, PubMed, Embase, and Web of Science. Quantitative synthesis was performed to report the strength of PON1-L55M polymorphism with breast cancer. Some bioinformatics tools were used to analyze the effects of L55M variation on PON1 gene function. The meta-analysis revealed that there are significant associations between the mentioned polymorphism and breast cancer in M vs. L, MM vs. LL, LM vs. LL, MM + LM vs. LL, and MM vs. LL + LM genetic models. Besides, similar results were observed in the stratified analyses based on ethnicity, genotyping method, Hardy-Weinberg equilibrium in control groups, and sample size. Bioinformatics analysis revealed that the PON1 could be damaging to the protein function. Our findings propose that the PON1-L55M genetic polymorphism might be a genetic risk factor for the risk of breast cancer.

Effect of Carotenoids on Paraoxonase-1 Activity and Gene Expression

Paraoxonase 1 (PON1) is an antioxidant enzyme attached to HDL with an anti-atherogenic potential. It protects LDL and HDL from lipid peroxidation. The enzyme is sensitive to various modulating factors, such as genetic polymorphisms as well as pharmacological, dietary (including carotenoids), and lifestyle interventions. Carotenoids are nutritional pigments with antioxidant activity. The aim of this review was to gather evidence on their effect on the modulation of PON1 activity and gene expression. Carotenoids administered as naturally occurring nutritional mixtures may present a synergistic beneficial effect on PON1 status. The effect of carotenoids on the enzyme depends on age, ethnicity, gender, diet, and PON1 genetic variation. Carotenoids, especially astaxanthin, β-carotene, and lycopene, increase PON1 activity. This effect may be explained by their ability to quench singlet oxygen and scavenge free radicals. β-carotene and lycopene were additionally shown to upregulate PON1 gene expression. The putative mechanisms of such regulation involve PON1 CpG-rich region methylation, Ca(2+)/calmodulin-dependent kinase II (CaMKKII) pathway induction, and upregulation via steroid regulatory element-binding protein-2 (SREBP-2). More detailed and extensive research on the mechanisms of PON1 modulation by carotenoids may lead to the development of new targeted therapies for cardiovascular diseases.

Engineering consortia by polymeric microbial swarmbots

Synthetic microbial consortia represent a new frontier for synthetic biology given that they can solve more complex problems than monocultures. However, most attempts to co-cultivate these artificial communities fail because of the winner-takes-all in nutrients competition. In soil, multiple species can coexist with a spatial organization. Inspired by nature, here we show that an engineered spatial segregation method can assemble stable consortia with both flexibility and precision. We create microbial swarmbot consortia (MSBC) by encapsulating subpopulations with polymeric microcapsules. The crosslinked structure of microcapsules fences microbes, but allows the transport of small molecules and proteins. MSBC method enables the assembly of various synthetic communities and the precise control over the subpopulations. These capabilities can readily modulate the division of labor and communication. Our work integrates the synthetic biology and material science to offer insights into consortia assembly and serve as foundation to diverse applications from biomanufacturing to engineered photosynthesis.

Occupational exposure to pesticides in farmworkers and the oxidative markers

Organophosphate (OPPs) and organochlorine pesticides (OCPs) are the two predominant forms of pesticides extensively used all around the world and are being reconsidered as environmental pollutants. The current study sought to assess the role of socioeconomic factors on the level of pesticides residues and the oxidative effects of exposure to OPPs and OCPs among the farmworkers of southeast Iran. In this cross-sectional study, 192 farmworkers and 74 non-farmworkers (controls) were involved. Gas chromatography (GC) was performed to measure the serum levels of organochlorine chemicals (2,4-DDT, 4,4-DDT, 2,4-DDE, 4,4-DDE, α-HCH, β-HCH, and γ-HCH). Furthermore, acetylcholinesterase (AChE) activity, arylesterase activity of paraoxonase-1 (PON-1), and several oxidative stress (OS) markers were assessed. In addition, the impact of several parameters such as home to farm distance, education level, ventilation status, and personal protective equipment (PPE) on pesticide levels was analyzed. The levels of OCPs in the farmworkers were significantly higher than the control subjects. In addition, AChE activity, arylesterase activity of PON-1, and total antioxidant capacity in farmworkers were significantly less, and MDA levels were higher than the controls. Education level was associated with farmworkers' protective behavior. The current findings suggested that some phased out OCPs can still be measured in human samples in the southeast of Iran. Furthermore, the current study demonstrated that exposure to OCPs and OPPs was accompanied by adverse consequences regarding OS parameters and subsequent health problems. In addition, the findings of the present study suggest that improving farmworkers' education might be associated with reduced exposure to pesticides and less adverse health effects.

Shell Matrix Protein N38 of Pinctada fucata, Inducing Vaterite Formation, Extends the DING Protein to the Mollusca World

In the animal kingdom, DING proteins were only found in Chordata and Aschelminthes. At present study, a potential DING protein, matrix protein N38, was isolated and purified from the shell of Pinctada fucata. Tandem mass spectrometry analysis revealed that 14 peptide segments matched between N38 and human phosphate-binding protein (HPBP). HPBP belongs to the DING protein family and has a "DINGGG-" sequence, which is considered a "signature" of HPBP. In this study, the mass spectrometry analysis results showed that N38 had a "DIDGGG-" sequence; this structure is a mutation from the "DINGGG-" structure, which is a distinctive feature of the DING protein family. The role of N38 during calcium carbonate formation was explored through the in vitro crystallization experiment. The results of scanning electron microscopy and Raman spectrum analysis indicated that N38 induced vaterite formation. These findings revealed that N38 might regulate and participate in the precise control of the crystal growth of the shell, providing new clues for biomineralization mechanisms in P. fucata and DING protein family studies. In addition, this study helped extend the research of DING protein to the Mollusca world.

Homocysteine, Vitamins B6 and Folic Acid in Experimental Models of Myocardial Infarction and Heart Failure—How Strong Is That Link?

Cardiovascular diseases are the leading cause of death and the main cause of disability. In the last decade, homocysteine has been found to be a risk factor or a marker for cardiovascular diseases, including myocardial infarction (MI) and heart failure (HF). There are indications that vitamin B6 plays a significant role in the process of transsulfuration in homocysteine metabolism, specifically, in a part of the reaction in which homocysteine transfers a sulfhydryl group to serine to form α-ketobutyrate and cysteine. Therefore, an elevated homocysteine concentration (hyperhomocysteinemia) could be a consequence of vitamin B6 and/or folate deficiency. Hyperhomocysteinemia in turn could damage the endothelium and the blood vessel wall and induce worsening of atherosclerotic process, having a negative impact on the mechanisms underlying MI and HF, such as oxidative stress, inflammation, and altered function of gasotransmitters. Given the importance of the vitamin B6 in homocysteine metabolism, in this paper, we review its role in reducing oxidative stress and inflammation, influencing the functions of gasotransmitters, and improving vasodilatation and coronary flow in animal models of MI and HF.

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.

A PON for All Seasons: Comparing Paraoxonase Enzyme Substrates, Activity and Action including the Role of PON3 in Health and Disease

Paraoxonases (PONs) are a family of hydrolytic enzymes consisting of three members, PON1, PON2, and PON3, located on human chromosome 7. Identifying the physiological substrates of these enzymes is necessary for the elucidation of their biological roles and to establish their applications in the biomedical field. PON substrates are classified as organophosphates, aryl esters, and lactones based on their structure. While the established native physiological activity of PONs is its lactonase activity, the enzymes’ exact physiological substrates continue to be elucidated. All three PONs have antioxidant potential and play an important anti-atherosclerotic role in several diseases including cardiovascular diseases. PON3 is the last member of the family to be discovered and is also the least studied of the three genes. Unlike the other isoforms that have been reviewed extensively, there is a paucity of knowledge regarding PON3. Thus, the current review focuses on PON3 and summarizes the PON substrates, specific activities, kinetic parameters, and their association with cardiovascular as well as other diseases such as HIV and cancer.

HDL Accessory Proteins in Parkinson’s Disease—Focusing on Clusterin (Apolipoprotein J) in Regard to Its Involvement in Pathology and Diagnostics—A Review

Parkinson’s disease (PD)—a neurodegenerative disorder (NDD) characterized by progressive destruction of dopaminergic neurons within the substantia nigra of the brain—is associated with the formation of Lewy bodies containing mainly α-synuclein. HDL-related proteins such as paraoxonase 1 and apolipoproteins A1, E, D, and J are implicated in NDDs, including PD. Apolipoprotein J (ApoJ, clusterin) is a ubiquitous, multifunctional protein; besides its engagement in lipid transport, it modulates a variety of other processes such as immune system functionality and cellular death signaling. Furthermore, being an extracellular chaperone, ApoJ interacts with proteins associated with NDD pathogenesis (amyloid β, tau, and α-synuclein), thus modulating their properties. In this review, the association of clusterin with PD is delineated, with respect to its putative involvement in the pathological mechanism and its application in PD prognosis/diagnosis.

HDL Composition, Heart Failure, and Its Comorbidities

Although research on high-density lipoprotein (HDL) has historically focused on atherosclerotic coronary disease, there exists untapped potential of HDL biology for the treatment of heart failure. Anti-oxidant, anti-inflammatory, and endothelial protective properties of HDL could impact heart failure pathogenesis. HDL-associated proteins such as apolipoprotein A-I and M may have significant therapeutic effects on the myocardium, in part by modulating signal transduction pathways and sphingosine-1-phosphate biology. Furthermore, because heart failure is a complex syndrome characterized by multiple comorbidities, there are complex interactions between heart failure, its comorbidities, and lipoprotein homeostatic mechanisms. In this review, we will discuss the effects of heart failure and associated comorbidities on HDL, explore potential cardioprotective properties of HDL, and review novel HDL therapeutic targets in heart failure.

Paraoxonase 2 is an ER chaperone that regulates the epithelial Na+ channel

The mammalian paraoxonases (PONs) have been linked to protection against oxidative stress. However, the physiological roles of members in this family (PON1, PON2, and PON3) are still being characterized. PON2 and PON3 are expressed in the aldosterone-sensitive distal nephron of the kidney and have been shown to negatively regulate expression of the epithelial sodium channel (ENaC), a trimeric ion channel that orchestrates salt and water homeostasis. To date, the nature of this phenomenon has not been explored. Therefore, to investigate the mechanism by which PON2 regulates ENaC, we expressed PON2 along with the ENaC subunits in fisher rat thyroid (FRT) cells, a system that is amenable to biochemical analyses of ENaC assembly and trafficking. We found that PON2 primarily resides in the endoplasmic reticulum (ER) in FRT cells, and its expression reduces the abundance of each ENaC subunit, reflecting enhanced subunit turnover. In contrast, no effect on the levels of mRNAs encoding the ENaC subunits was evident. Inhibition of lysosome function with chloroquine or NH4Cl did not alter the inhibitory effect of PON2 on ENaC expression. In contrast, PON2 accelerates ENaC degradation in a proteasome-dependent manner and acts before ENaC subunit ubiquitination. As a result of enhanced ENaC subunit ubiquitination and degradation, both channel surface expression and ENaC-mediated Na+ transport in FRT cells were reduced by PON2. Together, our data suggest that PON2 functions as an ER chaperone to monitor ENaC biogenesis and redirects the channel for ER-associated degradation.

Arylesterase activity of paraoxonase 1 in patients with primary hypertension

Introduction

Paraoxonase 1 is an enzyme associated with high-density lipoprotein fraction and is considered to present antioxidant activity.

Objectives

The aim of the study was to assess the arylesterase activity of paraoxonase 1 (PON1) in the serum of patients with hypertension, due to effect of therapy and before treatment. Patients and Methods. The study was conducted in 76 patients with primary hypertension and 28 volunteers for the control group. Hypertensive subjects were assigned to one of three groups: well controlled (n=25), poorly controlled (n=26), and newly diagnosed before therapy (n=25) hypertension. We evaluated metabolic parameters in all participants using routine laboratory methods, as well as arylesterase activity of PON1.

Results

The four study groups differed with arylesterase activity of PON1 and the highest levels were found in patients with well controlled hypertension and the lowest in newly diagnosed. All patients diagnosed with hypertension presented negative correlations between PON1 and systolic and diastolic blood pressure.

Conclusions

Effective treatment of hypertension could result in increased PON1 activity, despite unfavorable homocysteine concentrations in blood. Untreated hypertension might decrease activity of PON.

Review of cadmium exposure and smoking-independent effects on atherosclerotic cardiovascular disease in the general population

BACKGROUND

Exposure to cadmium (Cd) via food and smoking is associated with an increased risk of atherosclerotic cardiovascular disease (ASCVD). Blood and urine levels of Cd are established biomarkers of exposure.

OBJECTIVES

To review (1) the smoking-independent associations between Cd exposure and ASCVD, including the possible presence of a nonlinear dose-response relationship with Cd exposure and (2) the causal effects of Cd exposure on different stages of atherosclerosis.

METHODS

Narrative review.

RESULTS

Cd confers increased risk of ASCVD and asymptomatic atherosclerosis in the carotid and coronary arteries above B-Cd >0.5 μg/L or U-Cd >0.5 μg/g creatinine, but it has not been shown below a threshold of these exposure levels. Adjustment for smoking does not exclude the possibility of residual confounding, but several studies in never-smoking cohorts have shown associations between Cd and ASCVD, and experimental studies have demonstrated pro-atherosclerotic effects of Cd. Cd accumulates in arterial walls and atherosclerotic plaques, reaching levels shown to have proatherosclerotic effects. Suggested early effects are increased subendothelial retention of atherogenic lipoproteins, which become oxidized, and endothelial dysfunction and damage with increased permeability for monocytes, which in the intima turn to macrophages and then to foam cells. Later, Cd may contribute to plaque rupture and erosion by endothelial apoptosis and degradation of the fibrous cap. Finally, by having prothrombotic and antifibrinolytic effects, the CVD risk may be further increased.

CONCLUSIONS

There is strong evidence that Cd causes ASCVD above a suggested exposure level via mechanisms in early as well as the late stages of atherosclerotic disease.

Dietary Strategies to Improve Cardiovascular Health: Focus on Increasing High-Density Lipoprotein Functionality

Cardiovascular disease is one of the leading causes of morbidity and mortality worldwide, with increasing incidence. A cornerstone of cardiovascular disease prevention is lifestyle modification through dietary changes to influence various risk factors such as obesity, hypertension and diabetes. The effects of diet on cardiovascular health are complex. Some dietary components and metabolites directly affect the composition and structure of high-density lipoproteins (HDL) and increase anti-inflammatory and vasoprotective properties. HDLs are composed of distinct subpopulations of particles of varying size and composition that have several dynamic and context-dependent functions. The identification of potential dietary components that improve HDL functionality is currently an important research goal. One of the best-studied diets for cardiovascular health is the Mediterranean diet, consisting of fish, olive oil, fruits, vegetables, whole grains, legumes/nuts, and moderate consumption of alcohol, most commonly red wine. The Mediterranean diet, especially when supplemented with extra virgin olive oil rich in phenolic compounds, has been shown to markedly improve metrics of HDL functionality and reduce the burden, or even prevent the development of cardiovascular disease. Particularly, the phenolic compounds of extra virgin olive oil seem to exert the significant positive effects on HDL function. Moreover, supplementation of anthocyanins as well as antioxidants such as lycopene or the omega-3 fatty acid eicosapentaenoic acid improve parameters of HDL function. In this review, we aim to highlight recent discoveries on beneficial dietary patterns as well as nutritional components and their effects on cardiovascular health, focusing on HDL function.

Association between Paraoxonase-1 p.Q192R Polymorphism and Coronary Artery Disease susceptibility in the Colombian Population

Background

Paraoxonase-1 (PON1), a glycoprotein associated with serum high-density lipoprotein (HDL), has a central role in metabolizing lipid peroxides, exhibiting antiatherogenic properties. The polymorphism p.Q192R has been previously associated with coronary artery disease (CAD) susceptibility and clopidogrel response.

Purpose

We aimed at investigating the association of PON1 p.Q192R with CAD and clopidogrel response in Colombian population.

Patients and Methods

The study was conducted among 163 patients diagnosed with CAD and treated with clopidogrel. The allele frequencies for the PON1 192Q and 192R alleles were determined in cases and Latin-American controls obtained from the public database gnomAD (n = 17,711). Response to clopidogrel was determined by assessing the platelet function using the INNOVANCE PFA-200 System. We determined the association between PON1 p.Q192R polymorphism, increased susceptibility to CAD and high on-treatment platelet reactivity (HPR) by using odds ratio (OR) and 95% confidence interval (CI) on four genetic models.

Results

The allele frequencies for the PON1 192Q and 192R alleles were 0.60 and 0.40, respectively. The allele distribution was found to be statistically different from the control group and other ethnic groups. The allele 192R was positively associated with decreased susceptibility to CAD under a dominant model (OR, 0.58; 95% CI, 0.42–0.8; P < 0.01). We found no association between the polymorphism and HPR.

Conclusion

We propose that PON1 p.Q192R is a potentially useful marker for CAD susceptibility in the Colombian population and lacks association with HPR under clopidogrel treatment.

Gene Expression Profiling of Skeletal Muscles

Next-generation sequencing provides an opportunity for an in-depth biocomputational analysis to identify gene expression patterns between soleus and tibialis anterior, two well-characterized skeletal muscles, and analyze their gene expression profiling. RNA read counts were analyzed for differential gene expression using the R package edgeR. Differentially expressed genes were filtered using a false discovery rate of less than 0.05 c, a fold-change value of more than twenty, and an association with overrepresented pathways based on the Reactome pathway over-representation analysis tool. Most of the differentially expressed genes associated with soleus are coded for components of lipid metabolism and unique contractile elements. Differentially expressed genes associated with tibialis anterior encoded mostly for glucose and glycogen metabolic pathway regulatory enzymes and calcium-sensitive contractile components. These gene expression distinctions partly explain the genetic basis for skeletal muscle specialization, and they may help to explain skeletal muscle susceptibility to disease and drugs and further refine tissue engineering approaches.

l-Glutamine supplementation enhances glutathione peroxidase and paraoxonase-1 activities in HDL of exercising older individuals

BACKGROUND

Oxidative stress is an important factor in the formation of atherosclerotic plaques. High-density lipoprotein (HDL) harbors paraoxonase-1 (PON-1) and glutathione peroxidase (GPx), key enzymes in the protection against the harmful effects of oxidative stress. Although exercise training can increase both HDL-c content and its antioxidant action, and glutamine (Gln) intake also promotes GPx-based defenses, the association between exercise training and Gln in the regulation of PON-1 activity was not explored. Therefore, the objective of this study was to investigate the effects of Gln supplementation on the redox balance and on the total HDL antioxidant capacity by evaluation of the activity of PON-1 and GPx enzymes in physically exercised elderly individuals compared to non-exercised ones.

METHODS

Fifty-one practitioners of a combined exercise training program (CET, age: 71.9 ± 5.7 years) and 32 non-practitioners (NP, age: 73 ± 6.3 years) participated in the study. CET and NP groups were separated into 2 subgroups according to the supplementation: Gln, 0.3 g/kg/day + 10 g maltodextrin (CET-Gln, n = 26; and NP-Gln, n = 16) or placebo, 10 g maltodextrin (CET-PL, n = 25; and NP-PL, n = 16). Blood samples were drawn at baseline and after 30 days after commencement of the supplementation for biochemical and enzyme activity analyses.

RESULTS

Increased HDL-c, total peroxidase (PRx), and GPx activities were found in both CET-Gln and NP-Gln after the supplementation period, compared to baseline, in opposition to CET-PL and NP-PL groups. PON-1 activity increased only in CET-Gln. In both CET-Gln and NP-Gln groups, there was a reduction of the total peroxides/PRx, iron/PRx, and total peroxides/GPX ratios after supplementation. In CET-Gln, thiobarbituric acid-reactive substances (TBARS)/PRx and TBARS/GPx ratios were also lower after supplementation. CET-Gln and CET-PL subgroups had lower glycemia than NP-Gln and NP-PL, either at baseline or after the supplementation periods. The other parameters were unchanged after supplementation [total cholesterol, LDL-c, triglycerides, non-HDL cholesterol, total peroxides, TBARS, iron serum, Trolox-equivalent antioxidant capacity (TEAC), and uric acid].

CONCLUSIONS

Gln supplementation can increase glutathione peroxidase activity regardless the individuals were physically active or sedentary, but the PON-1 activity only increased in physically active individuals. These results show the potential of Gln supplementation in the maintenance of the vascular redox balance, with potential implications for atherogenesis protection.

Altered HDL Proteome Predicts Incident CVD in Chronic Kidney Disease Patients

Patients with chronic kidney disease (CKD) are at high risk for CVD. However, traditional lipid risk factors, including low HDL levels, cannot completely explain the increased risk. Altered HDL proteome is linked with both CVD and CKD, but the role of HDL proteins in incident CVD events in patients with CKD is unknown. In this prospective case-control study, we used targeted proteomics to quantify 31 HDL proteins in 92 subjects (46 incident new CVD and 46 one-to-one matched controls) at various stages of CKD. We tested associations of HDL proteins with incident CVD using matched logistic regression analysis. In the model fully adjusted for clinical confounders, lipid levels, C-reactive protein, and proteinuria, no significant associations were found for HDL-C, but we observed inverse associations between levels of HDL proteins paraoxonase/arylesterase 1 (PON1), paraoxonase/arylesterase 3 (PON3), and LCAT and incident CVD. Odds ratios (per 1 SD) were 0.38 (0.18–0.97, P = 0.042), 0.42 (0.20–0.92, P = 0.031), and 0.30 (0.11–0.83, P = 0.020) for PON1, PON3, and LCAT, respectively. Apolipoprotein A-IV remained associated with incident CVD in CKD patients in models adjusted for clinical confounders and lipid levels but lost significance with the addition of C-reactive protein and proteinuria to the model. In conclusion, levels of four HDL proteins, PON1, PON3, LCAT, and apolipoprotein A-IV, were found to be inversely associated with incident CVD events in CKD patients. Our observations indicate that HDLs' protein cargo, but not HDL-C levels, can serve as a marker—and perhaps mediator—for elevated CVD risk in CKD patients.