Association between promoter polymorphism (-108C>T) of paraoxonase1 gene and it's paraoxonase activity in patients with Type2 diabetes in northern Iran

Serum Arylesterase, Paraoxonase, and Lactonase Activities and Paraoxonase-1 Concentrations in Morbidly Obese Patients and Their Relationship with Non-Alcoholic Steatohepatitis

Paraoxonase-1 (PON1) is an antioxidant enzyme associated with high-density lipoproteins (HDL). Reduced serum PON1 activity is found in diseases marked by oxidative stress and inflammation, but its role in obesity remains unclear. This study investigated PON1 activities and concentrations in morbidly obese individuals and explored the impacts of the genetic polymorphism PON1 rs662 and non-alcoholic fatty liver disease on enzymatic properties. We recruited 1349 morbidly obese patients undergoing bariatric surgery and 823 non-obese volunteers. PON1-related variables, including arylesterase, paraoxonase, and lactonase activities and PON1 concentrations, were examined. Our results showed that morbidly obese individuals exhibited higher PON1 concentrations but lower enzymatic activities than non-obese individuals. We observed inverse associations of arylesterase and paraoxonase activities with waist circumference (rho = -0.24, p < 0.001, and rho = -0.30, p < 0.001, respectively) and body mass index (rho = -0.15, p = 0.001, and rho = -0.23, p < 0.001), as well as direct associations of arylesterase, paraoxonase, and lactonase activities with HDL cholesterol (rho = 0.11, p = 0.005, rho = 0.20, p < 0.001, and rho = 0.20, p < 0.001). No significant differences were observed regarding metabolic syndrome, type 2 diabetes mellitus, hypertension, dyslipidemia, rs662 polymorphism allele frequencies, or the diagnosis of non-alcoholic steatohepatitis. Nevertheless, correlations were found between certain PON1-related variables, steatosis, and ballooning. In conclusion, changes in PON1-related variables in morbidly obese patients are dependent on the disease itself and HDL levels. The relationships between these variables and specific liver histological changes raise intriguing questions for consideration in future studies.

Single-nucleotide polymorphisms as important risk factors of diabetes among Middle East population

Diabetes is a chronic metabolic disorder that leads to the dysfunction of various tissues and organs, including eyes, kidneys, and cardiovascular system. According to the World Health Organization, diabetes prevalence is 8.8% globally among whom about 90% of cases are type 2 diabetes. There are not any significant clinical manifestations in the primary stages of diabetes. Therefore, screening can be an efficient way to reduce the diabetic complications. Over the recent decades, the prevalence of diabetes has increased alarmingly among the Middle East population, which has imposed exorbitant costs on the health care system in this region. Given that the genetic changes are among the important risk factors associated with predisposing people to diabetes, we examined the role of single-nucleotide polymorphisms (SNPs) in the pathogenesis of diabetes among Middle East population. In the present review, we assessed the molecular pathology of diabetes in the Middle East population that paves the way for introducing an efficient SNP-based diagnostic panel for diabetes screening among the Middle East population. Since, the Middle East has a population of 370 million people; the current review can be a reliable model for the introduction of SNP-based diagnostic panels in other populations and countries around the world.

The Relevance of Noncoding DNA Variations of Paraoxonase Gene Cluster in Atherosclerosis-Related Diseases

The human paraoxonase (PON) gene cluster is comprised of three contiguous genes (PON1, PON2 and PON3) of presumably common origin coding three lactonases of highly similar structure and substrate specificity. The catalytic activity of PON proteins is directed toward artificial organophosphates and in physiological conditions toward thiolactones and oxidized phospholipids. Consequently, PON enzymes are regarded as an effective defense against oxidative stress and, as a result, against atherosclerosis development. Additionally, both PON's serum activity and its concentration are influenced by several polymorphic variations in coding and noncoding DNA regions of the PON gene cluster remaining in linkage disequilibrium. Hence, the genetic polymorphism of the PON gene cluster may contribute to atherosclerotic process progression or deceleration. In this review the authors analyzed the relevance of noncoding DNA polymorphic variations of PON genes in atherosclerosis-related diseases involving coronary and peripheral artery disease, stroke, diabetes mellitus, dementia and renal disease and concluded that the effect of PON gene cluster' polymorphism has a considerable impact on the course and outcome in these conditions. The following PON genetic variations may serve as additional predictors of the risk of atherosclerosis in selected populations and individuals.

Evaluation of Relationship Between Arylesterase-Based Activity and Genetic Variants of Paraoxonase1 in T2DM Patients within Golestan Province

Arylesterase activity of Paraoxonase-1 (PON1) enzyme may be play important role in initiation and progression of several diseases. Activity or serum level of Arylesterase can be affected by many genetic alterations such as SNPs. The reduction in the activity and serum level of Arylesterase could be involved in Type2 diabetes mellitus (T2DM). The aim of this investigation is to examine the association between Arylesterase activity and promoter polymorphism (- 108C > T) of PON1gene in patients with T2DM in Golestan Province, northern area of Iran. Achievement of this purpose was due to DNA obtaining from blood then SNP determination using PCR-RFLP and Arylesterase activity measurement in the serum of 90 normal individuals and 90patients suffering diabetes. Data was processed by SPSS software version 16. The significant association was observed between the Arylesterase activity and three genotypes of PON1 gene such as CC, CT, and TT in subjects with T2DM. In the present study, it has been shown level of Arylestrase activity of PON1 in patients (117.33 ± 63.96) is lower than it in control group (289.33 ± 68.38); P < 0.05. Our results declared that activity of Arylesterase in diabetic patients was significantly lower than the healthy individuals.

Plasma paraoxonase1 activity in rats treated with monocrotophos: a study of the effect of duration of exposure

We have earlier demonstrated the potential of monocrotophos (MCP), a highly toxic organophosphorus insecticide (OPI), to elicit insulin resistance in rats after chronic exposure. Given the understanding of role of paraoxonase1 (PON1) in OPI toxicity and diabetes pathology, this study was envisaged to understand the effect of duration of exposure to MCP on plasma PON1 activity in rats. Rats were administered MCP per os at 1/20 and 1/10^th LD₅₀ as daily doses for 180 days. Interim blood samples were collected at 15, 30, 45, 90 and 180 d for analysis of plasma parameters. Exposure to MCP for 45 resulted in persistent trend of hyperinsulinemia, while significant increase in fasting glucose levels was observed after 180 days. MCP caused suppression of plasma cholinesterase activity though the study period, albeit extent of inhibition was more severe during the early phase of the study. Exposure to MCP for 180 d resulted in hypertriglyceridemia and marginal decrease in HDL-C levels. MCP failed to modulate PON1 activity in plasma during the early phase of the study (up to 45 d). However, prolonged exposure resulted in significant increase in the plasma PON1 activity. This suggests that manifestation of insulin resistance in rats subjected to chronic exposure to MCP is associated with increase in PON1 activity. Our work provides rationale for studying whether the increase in PON1 activity observed in the present study serves to counter the deleterious effect of long term exposure to organophosphorus insecticides on metabolic homeostasis.

Association of combined genetic variations in SOD3, GPX3, PON1, and GSTT1 with hypertension and severity of coronary artery disease

Oxidative stress plays a critical role in the pathophysiology of hypertension (HT) and the progression of atherosclerotic coronary artery disease (CAD). Genetic variations in superoxide dismutase (SOD), glutathione peroxidase 3 (GPX3), paraoxonase 1 (PON1) and glutathione S-transferase theta 1 (GSTT1) may modulate their gene functions, affecting protein functions. These changes could have an impact on the pathogenesis of HT and progression of CAD. The present study investigated the associations of individual and combined antioxidant-related gene polymorphisms with the incidence of HT and severity of CAD. Two study populations were enrolled. The HT-associated study comprised 735 control and 735 hypertensive subjects (mean age 59.3 ± 9.0 years), matched for age and sex. The CAD study, hospital-based subjects (mean age 62.1 ± 9.5 years), included 279 CAD patients and 165 non-CAD subjects. Gene polymorphisms were identified in genomic DNA using polymerase chain reaction (PCR)-based technique. Genetic variations were assessed for their associations with HT and severity of CAD. Antioxidant gene variants, SOD3 rs2536512-GG, GPX3 rs3828599-GG, PON1 rs705379-TT, and GSTT1^{-/- and +/-}, were independently associated with the incidence of HT. A combination of four HT-associated genotypes, as a genetic risk score (GRS), revealed an association of GRS 5 and GRS ≥ 6 with increased susceptibility to HT and CAD, and further with multivessel coronary atherosclerosis (multivessel CAD) compared with GRS 0-2 [respective ORs(95% CI) for GRS ≥ 6 = 2.37 (1.46-3.85), 3.26 (1.29-8.25), and 4.36 (1.36-14.0)]. Combined polymorphisms in these four antioxidant-related genes were associated with the incidences of HT and CAD, and with the severity of coronary atherosclerosis.

The most effective polymorphisms of paraoxonase-1 gene on enzyme activity and concentration of paraoxonase-1 protein in type 2 diabetes mellitus patients and non-diabetic individuals: A systematic review and meta-analysis

INTRODUCTION

Many studies have evaluated the association of paraoxonase-1 (PON1) gene polymorphisms with enzyme activity and concentration in type 2 diabetes mellitus (T2DM). However, the exact impact of these polymorphisms is not still obvious. Hence, we conducted a systematic review and meta-analysis to clarify the association of PON1 polymorphisms with its enzyme characteristics in T2DM patients and non-diabetic individuals.

METHODS

We searched electronic databases including PubMed, Web of Science, Embase and Scopus for publications by April 2018. The pooled response ratio (rr) for the association and their corresponding 95% confidence intervals (CIs) were calculated using a fixed-effect model.

RESULTS

Fifteen relevant studies fulfilled our inclusion criteria. The results showed a 1.25-fold increase in total PON1 activity in non-diabetic group against T2DM patients (p-value = 0.024). Also, only Q192R and L55M polymorphisms had sufficient studies to be included in the meta-analysis. All three genotypes of Q192R polymorphism showed significantly different activities between the study groups with the highest pooled effect size for RR genotype (rr_QQ < rr_QR < rr_RR) while this difference was seen only in LL genotype of L55M polymorphism. Therefore, Q192R polymorphism was more correlated with type 2 diabetes mellitus. In case of concentration, there was no significant differences between two groups (p-value = 0.897).

CONCLUSION

Current meta-analysis suggested that the observed difference of total PON1 activity was due to the different activity of various genotypes of PON1 enzyme in case of L55M and Q192R polymorphisms so that LL and RR genotypes had the most important role in the establishment of mentioned difference.

Circulating Oxidative Stress Biomarkers in Clinical Studies on Type 2 Diabetes and Its Complications

Type 2 diabetes (T2DM) and its complications constitute a major worldwide public health problem, with high rates of morbidity and mortality. Biomarkers for predicting the occurrence and development of the disease may therefore offer benefits in terms of early diagnosis and intervention. This review provides an overview of human studies on circulating biomarkers of oxidative stress and antioxidant defence systems and discusses their usefulness from a clinical perspective. Most case-control studies documented an increase in biomarkers of oxidative lipid, protein, and nucleic acid damage in patients with prediabetes and in those with a diagnosis of T2DM compared to controls, and similar findings were reported in T2DM with micro- and macrovascular complications compared to those without. The inconsistence of the results regarding antioxidant defence systems renders difficulty to draw a general conclusion. The clinical relevance of biomarkers of oxidative lipid and protein damage for T2DM progression is uncertain, but prospective studies suggest that markers of oxidative nucleic acid damage such as 8-hydroxy-2'-deoxyguanosine and 8-hydroxyguanosine are promising for predicting macrovascular complications of T2DM. Emerging evidence also points out the relationship between serum PON1 and serum HO1 in T2DM and its complications. Overall, enhanced oxidative damage represents an underlying mechanism of glucose toxicity in T2DM and its related micro- and macrovascular complications suggesting that it may be considered as a potential additional target for pharmacotherapy. Therefore, further studies are needed to understand whether targeting oxidative stress may yield clinical benefits. In this view, the measurement of oxidative stress biomarkers in clinical trials deserves to be considered as an additional tool to currently used parameters to facilitate a more individualized treatment of T2DM in terms of drug choice and patient selection.

Association of Serum Paraoxonase 1 Activities, Polymorphisms and Oxidative Stress in Breast Cancer Patients with Type 2 Diabetes Mellitus

Background

The aim of the study was to investigate the association of paraoxonase 1 (PON1) polymorphism, PON1/arylesterase (ARE) activity and oxidative stress index (OSI) in breast cancer (BC) patients with type 2 diabetes (DM).

Methods

Our study group consisted of 30 healthy women (HV group) and 66 female BC patients. The BC patients were divided into two groups: those with (n=37) and without DM (n=29) (BDM and NBDM group). Genotyping of PON1 Q192R and L55M polymorphisms were done by polymerase chain reaction (PCR) - restriction fragment length polymorphism (RFLP) method. Serum PON1/ARE enzyme activities, total oxidant status (TOS) and total antioxidant status (TAS) were analysed by spectrophotometric method. The ratio of TOS to TAS was accepted as the oxidative stress index (OSI).

Results

PON1 Q192R genotype frequency distribution was significantly different in the BDM group compared to the NBDM group (p=0.021). When alleles distribution was examined, R and L alleles were significantly lower, Q and M alleles were significantly higher in the BDM group than in the NBDM group (p<0.001). TOS and OSI were statistically higher in BC patients than HV group (p<0.001).

Conclusions

Our results suggest that PON1 gene Q and M alleles may be the risk factors predisposing formation of BC due to increased oxidant damage seen in DM. However, these statements require further confirmation with screening PON1 polymorphism in a greater number of patients with DM, and also wide range follow-up studies are necessary for the same purpose.

Paraoxonases Activities and Polymorphisms in Elderly and Old-Age Diseases: An Overview

Aging is defined as the accumulation of progressive organ dysfunction. There is much evidence linking the involvement of oxidative stress in the pathogenesis of aging. With increasing age, susceptibility to the development of diseases related to lipid peroxidation and tissue injury increases, due to chronic inflammatory processes, and production of reactive oxygen species (ROS) and free radicals. The paraoxonase (PON) gene family is composed of three members (PON1, PON2, PON3) that share considerable structural homology and are located adjacently on chromosome 7 in humans. The most studied member product is PON1, a protein associated with high-density lipoprotein with paraoxonase/esterase activity. Nevertheless, all the three proteins prevent oxidative stress. The major aim of this review is to highlight the importance of the role of PON enzymes in the aging process, and in the development of the main diseases present in the elderly: cardiovascular disease, diabetes mellitus, neurodegenerative diseases, and cancer.

The association between paraoxonase 1 activity and the susceptibilities of diabetes mellitus, diabetic macroangiopathy and diabetic microangiopathy

We carried out this meta‐analysis to explore the influence of paraoxonase 1 activity on the susceptibility of diabetes mellitus (DM), diabetic macroangiopathy and diabetic microangiopathy. Relevant studies were identified from PubMed, Web of Science and CNKI without language limitation, following the inclusion and exclusion criteria. Statistical analyses were implemented with the STATA 12.0 statistical software. Thirty‐six case‐control studies were included in the meta‐analyses, in which 35 for the association between paraoxonase 1 activity and DM risk, 8 for diabetic macroangiopathy and 7 for diabetic microangiopathy. Paraoxonase 1 activity was significantly associated with the susceptibility of DM in pooled population (SMD = −1.37, 95% CI = −1.79 ∼ −0.96, P = .000), and Asians (SMD = −2.00, 95% CI = −2.56 ∼ −1.44, P = .000), but not in non‐Asians (SMD = −0.44, 95% CI = −0.91 ∼ 0.03, P = .069). However, marked heterogeneity was existed (I² = 98.10%, P = .000) and subgroup analyses failed to investigate the sources of heterogeneity. Then, meta‐regression was performed and found that ethnicity could explain the observed between‐study heterogeneity (P = .002). Meanwhile, significant associations were found between paraoxonase 1 activity and diabetic macroangiopathy (SMD = −1.06, 95% CI = −1.63 ∼ −0.48, P = .000) and diabetic microangiopathy (SMD = −0.72, 95% CI = −1.32 ∼ −0.13, P = .018). In conclusion, paraoxonase 1 activity plays important roles in the risk of DM, diabetic macroangiopathy and microangiopathy with ethnicity differences. Further studies with large sample and well design are needed to confirm these results.