Sex difference: an important issue to consider in epidemiological and clinical studies dealing with serum paraoxonase-1

Plasma paraoxonase-1 activity levels in patients with type 2 diabetes mellitus in Lagos State University Teaching Hospital, Lagos, Southwest Nigeria: a cross-sectional study

Introduction

paraoxonase 1 (PON1) is a high-density lipoprotein (HDL) associated enzyme that has anti-inflammatory, anti-atherogenic, and antioxidant functions. PON1 is noted to be a determinant of resistance to the development of atherosclerosis through hydrolysis of phospholipid and cholesteryl ester hydroperoxides. This study was designed to assess PON1 activity levels among patients with type 2 diabetes mellitus (T2DM) in Southwest Nigeria.

Methods

this was a cross-sectional study done over a period of six months. A total of 138 participants; 69 with T2DM and 69 apparently healthy controls were recruited for this study. Fasting plasma glucose (FPG), HDL cholesterol (HDL-c), and PON1 activity were analyzed in the participants. The comparison of the mean between the groups of participants was assessed using the independent student t-test while the Mann-Whitney U test was used to compare two medians. The p-value was set at 0.05.

Results

mean age for participants with T2DM was 54.90 ± 8.1 years and the healthy control group was 54.12 ± 8.4 years, with a p-value of 0.549. The male-to-female ratio was 0.47 for both participants with T2DM and healthy controls. Participants with T2DM had significantly higher median glucose concentration of 109.18 mg/dl compared with 82.58 mg/dl among controls, p-value <0.001. Median serum HDL-c was lower in diabetics compared to controls (52.66 mg/dl vs 57.92 mg/dl; p-value < 0.001). PON1 activity was lower in T2DM compared with that of the controls (690.11 pmol/min/ml vs 3379.7 pmol/min/ml; p-value <0.001). Paroxonase 1 showed a non-significant positive correlation with HDL-c and a negative correlation with FPG, and body mass index (BMI).

Conclusion

these findings suggest that PON1 activity is lower in T2DM compared to healthy controls and a lower PON1 activity level was seen among female diabetics compared with the male diabetics.

Deciphering genetic causes for sex differences in human health through drug metabolism and transporter genes

Sex differences have been widely observed in human health. However, little is known about the underlying mechanism behind these observed sex differences. We hypothesize that sex-differentiated genetic effects are contributors of these phenotypic differences. Focusing on a collection of drug metabolism enzymes and transporters (DMET) genes, we discover sex-differentiated genetic regulatory mechanisms between these genes and human complex traits. Here, we show that sex-differentiated genetic effects were present at genome-level and at DMET gene regions for many human complex traits. These sex-differentiated regulatory mechanisms are reflected in the levels of gene expression and endogenous serum biomarkers. Through Mendelian Randomization analysis, we identify putative sex-differentiated causal effects in each sex separately. Furthermore, we identify and validate sex differential gene expression of a subset of DMET genes in human liver samples. We observe higher protein abundance and enzyme activity of CYP1A2 in male-derived liver microsomes, which leads to higher level of an active metabolite formation of clozapine, a commonly prescribed antipsychotic drug. Taken together, our results demonstrate the presence of sex-differentiated genetic effects on DMET gene regulation, which manifest in various phenotypic traits including disease risks and drug responses.

A Nutraceutical Compound Containing a Low Dose of Monacolin K, Polymethoxyflavones, Phenolic Acids, Flavonoids, and Hydroxytyrosol Improves HDL Functionality

BACKGROUND

In earlier studies, it has been observed that 8-week treatment with a novel nutraceutical compound (NC) containing low monacolin K dose, polymethoxyflavones, phenolic acids, flavonoids, and hydroxytyrosol improves lipid profile and endothelial function and reduces the level of oxidized low-density lipoprotein (oxLDL). We hypothesize that this effect might be, at least in part, explained by positive modulation exerted by the NC on the atheroprotective function of high-density lipoprotein (HDL).

AIM

This study aimed to evaluate whether the NC could influence determinants of HDL function.

METHODS

Forty-five subjects with low-moderate dyslipidaemia were enrolled and treated for 8 weeks with the NC, followed by 4 weeks of washout. Blood samples were collected at every time point to evaluate changes in lipid profile, endothelial function, oxLDL, and markers of HDL function, such as the anti-oxidant activities of paraoxonase-1, glutathione peroxidase-3 (Gpx3), lipoprotein-phospholipase A2 (Lp-PLA2), and pro-oxidant activity of myeloperoxidase (MPO).

RESULTS

Although the concentration of HDL-C did not change, the activity of Lp-PLA2 significantly decreased upon treatment (-11.6%, p<0.001) and returned to baseline level 4 weeks after the end of treatment. In contrast, Gpx3 increased after treatment (+5%, p<0.01) and remained unvaried after 4 weeks. Both MPO activity and concentration significantly decreased after the washout period (-33 and 32%, p<0.001).

CONCLUSION

For the first time, it was found that the administration of an NC with beneficial effects on lipid homeostasis also positively impacts HDL function by improving the balance between protective and damaging determinants. Further investigation is required to corroborate our findings.

Oxidative stress and antioxidant markers in patients with alopecia areata: A comparative cross-sectional study

Background

Alopecia areata is a chronic inflammatory skin disease. Oxidative stress may contribute to the pathogenesis of this condition.

Aim

To evaluate the serum oxidative stress markers and antioxidant capacity in patients with alopecia areata.

Methods

This cross-sectional study was performed on 40 patients with alopecia areata and 40 healthy controls. The fasting blood sugar, C-reactive protein, lipid profile, and serum oxidative markers, including advanced glycation end products and advanced oxidation protein products, were measured in this study. Also, antioxidant enzymes, including paraoxonase-1, lecithin-cholesterol acyltransferase and serum ferric-reducing antioxidant power, were determined.

Results

The serum levels of advanced glycation end products and advanced oxidation protein products were significantly higher in patients with alopecia areata, compared to the controls (P < 0.001), whereas the levels of ferric-reducing antioxidant power, paraoxonase-1 and lecithin-cholesterol acyltransferase were significantly lower in patients with alopecia areata, compared to the controls (P < 0.001). The mean fasting blood sugar level was significantly higher in patients with alopecia areata, compared to the controls. The ferric reducing antioxidant power level was significantly associated with the percentage of hair loss (P = 0.01, r = 0.4) and the serum C-reactive protein level (P = 0.03, r = -0.3) in patients with alopecia areata.

Limitations

Since the current study had a cross-sectional design, no cause-effect relationship was established between alopecia areata and oxidative stress. The sample size of our study was also small.

Conclusion

Based on the present results, the oxidant-antioxidant enzymatic system is impaired in alopecia areata due to the increased oxidative products and decreased antioxidant activity.

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.

High-density lipoproteins and immune response: A review

High-density lipoproteins (HDLs) are heterogeneous lipoproteins that modify their composition and functionality depending on physiological or pathological conditions. The main roles of HDL are cholesterol efflux, and anti-inflammatory and antioxidant functions. These functions can be compromised under pathological conditions. HDLs play a role in the immune system as anti-inflammatory molecules but when inflammation occurs, HDLs change their composition and carry pro-inflammatory cargo. Hence, many molecular intermediates that influence inflammatory microenvironments and cell signaling pathways can modulate HDLs structural modification and function. This review provides a comprehensive assessment of the importance of HDL composition and anti-inflammatory function in the onset and progression of atherosclerotic cardiovascular diseases. On the other hand, immune cell activation during progression of atheroma plaque formation can be influenced by HDLs through HDL-derived cholesterol depletion from lipid rafts and through HDL interaction with HDL receptors expressed on T and B lymphocytes. Cholesterol efflux is mediated by HDL receptors located in lipid rafts in peripheral cells, which undergo membrane structural modifications, and interferes with subsequent molecules interactions or intracellular signaling cascades. Regarding antigen-presentation cells such as macrophages or dendritic cells, HDL function may then modulate lymphocytes activation in immune response. Our review also contributes to the understanding of the effects exerted by HDLs in signal transduction associated to our immune cell population during chronic diseases progression.

Abnormal Paraoxonase-1 (PON1) enzyme activity in idiopathic inflammatory myopathies

OBJECTIVES

Patients with idiopathic inflammatory myopathies (IIM) have severe vascular involvement, which contributes to disease morbidity and mortality. Paraoxonase-1 (PON1) is a high-density lipoprotein (HDL) associated protein, which protects the vascular endothelium from oxidative injury and damage. The current work assessed the functional and genetic determinants of PON1 activity in IIM patients.

METHODS

184 IIM patients and 112 healthy controls (HC) were included. PON1 enzyme activity was assessed by paraoxonase, arylesterase and lactonase assays, and the Q192R PON1 single nucleotide polymorphism (SNP) was analyzed. Multivariate regression models examined associations of PON1 activity with IIM diagnosis and myositis disease outcomes.

RESULTS

The arylesterase and lactonase activities of PON1 were significantly lower in IIM patients compared with HC. Higher myositis disease activity, the presence of severe IIM associated interstitial lung disease (ILD), and the presence of MDA5 or anti-synthetase antibodies were significantly associated with lower PON1 activity. The PON1 Q192R polymorphism was strongly linked to the paraoxonase activity of PON1 in IIM, and patients with the PON1 QQ genotype had better IIM disease outcomes compared with patients with the QR or RR genotypes.

CONCLUSIONS

The arylesterase and lactonase activities of PON1 are significantly impaired in IIM patients compared with HC, and inversely associate with IIM disease activity and the presence of severe ILD. The PON1 QQ genotype associates with more favorable disease outcomes in IIM patients. Large prospective studies are needed to further evaluate the role of PON1 and PON1 genetic polymorphisms in the development and propagation of IIM and IIM-ILD.

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.

Sex Difference Impacts on the Relationship between Paraoxonase-1 (PON1) and Type 2 Diabetes

Type-2 diabetes (T2D) and its cardiovascular complications are related to sex. Increasing evidence suggests that paraoxonase 1 (PON1) activity, an antioxidant enzyme bound to high-density lipoproteins (HDL), is implicated in the onset and clinical progression of T2D. Since we previously showed that PON1 is a sexual dimorphic protein, we now investigated whether sex might impact the relationship between PON1 and this chronic disease. To address this aim, we assessed PON1 activity in the sera of 778 patients, including controls (women, n = 383; men, n = 198) and diabetics (women, n = 79; men = 118). PON1 activity decreased in both women and men with T2D compared with controls (p < 0.05 and p > 0.001, respectively), but the change was 50% larger in the female cohort. In line with this result, the enzyme activity was associated with serum glucose level only in women (r = -0.160, p = 0.002). Notably, only within this gender category, lower PON1 activity was independently associated with increased odds of being diabetic (odds ratio (95% Confidence interval: 2.162 (1.075-5.678)). In conclusion, our study suggests that PON1-deficiency in T2D is a gender-specific phenomenon, with women being more affected than men. This could contribute to the partial loss of female cardiovascular advantage associated with T2D.

Increased CSF Levels of Apolipoproteins and Complement Factors in Trigeminal Neuralgia Patients-In Depth Proteomic Analysis Using Mass Spectrometry

The main cause of trigeminal neuralgia (TN) is compression of a blood vessel at the root entry zone of the trigeminal nerve. However, a neurovascular conflict does not seem to be the only etiology and other mechanisms are implicated in the development of the disease. We hypothesized that TN patients may have distinct protein expression in the CSF. In this study, lumbar CSF from TN patients (n = 17), scheduled to undergo microvascular decompression, and from controls (n = 20) was analyzed and compared with in depth mass spectrometry TMTbased quantitative proteomics. We identified 2552 unique proteins, of which 46 were significantly altered (26 increased, and 20 decreased, q-value < .05) in TN patients compared with controls. An over-representation analysis showed proteins involved in high-density lipoprotein, such as Apolipoprotein A4, Apolipoprotein M, and Apolipoprotein A1, and the extracellular region, including proteins involved in the complement cascade to be over-represented. We conclude that TN patients have distinct protein expression in the CSF compared to controls. The pathophysiological background of the protein alterations found in this study warrants further investigation in future studies. PERSPECTIVE: In this article, cerebrospinal fluid from patients with trigeminal neuralgia was analyzed using in depth shotgun proteomics, revealing 46 differentially expressed proteins compared to controls. Among these, apolipoproteins and proteins involved in the complement system were elevated and significantly over-represented, implying an inflammatory component in the pathophysiology of the disease.

An association of blood mercury levels and hypercholesterolemia among Korean adolescents

PURPOSE

A few experimental studies have suggested that mercury exposure might be associated with dyslipidemia, possibly through its interference with the activities of genes and enzymes involved in lipid metabolism. Mercury exposure has been associated with the risk of dyslipidemia and cardiovascular disease in previous adult studies. However, only a few studies have been conducted in pediatric populations. We aimed to assess the associations between total blood mercury concentrations and lipid profiles in Korean adolescents.

METHODS

The study population comprised 1890 adolescents (963 males and 927 females; age: 10-19 years) who participated in the Korea National Health and Nutrition Examination Survey 2010-2013 and 2016 and whose fasting blood samples were obtained to determine their blood mercury concentrations and lipid profiles. We analyzed the distribution of lipid profiles and the prevalence of dyslipidemia based on the total blood mercury concentrations.

RESULTS

The geometric mean of the blood mercury concentration was 1.89 μg/L and was significantly higher in males (1.96 μg/L) than in females (1.83 μg/L). The total cholesterol and low-density lipoprotein (LDL) cholesterol levels significantly increased as the blood total mercury concentration increased in males, not in females. High-density lipoprotein cholesterol and triglyceride levels did not show significant associations with total blood mercury levels. The prevalence of hyper-LDL-cholesterolemia also significantly increased in the highest blood mercury quartile group compared with that in the lowest blood mercury quartile group in males (P-for-trend <0.001). Male adolescents in the highest total blood mercury quartile group were found to be at higher risk of hypercholesterolemia than those in the lowest quartile group after adjusting for the covariates including obesity [odds ratios (95% confidential interval): 3.72 (1.03-13.4)]. Total blood mercury quartile showed a positive linear relationship with the risk of hyper-LDL-cholesterolemia after controlling for the covariates in males.

CONCLUSION

Our results suggest the potential association between mercury exposure and the risk of hyper-LDL-cholesterolemia in male adolescents.