Correlation of plasma oxidized low-density lipoprotein levels to vascular complications and human serum paraoxonase in patients with type 2 diabetes

Exploring the protective role of green tea extract against cardiovascular alterations induced by chronic REM sleep deprivation via modulation of inflammation and oxidative stress

BACKGROUND

Chronic Rapid eye movement (REM) sleep deprivation has been associated with various cardiovascular alterations, including disruptions in antioxidant defense mechanisms, lipid metabolism, and inflammatory responses. This study investigates the therapeutic potential of green tea extract (GTE) in mitigating these adverse effects.

METHODS

A total of 24 male Wistar albino rats were used in this study and divided into the control group (n = 8), Chronic-REM Sleep Deprivation (CRSD) Group (n = 8) and Chronic-REM SD + Green Tea 200 (CRSD + GTE200) Group (n = 8). After 21 days, a comprehensive analysis of paraoxonase (PON1), arylesterase (ARE), malondialdehyde (MDA), glutathione (GSH), nitric oxide (NOx), proinflammatory cytokines, and lipid profiles in aortic tissue, heart tissue, and serum was conducted in a sleep-deprived rat model.

RESULTS

Chronic REM sleep deprivation led to a significant reduction in PON1 and ARE levels in aortic (p = 0.046, p = 0.035 respectively) and heart tissues (p = 0.020, p = 0.019 respectively), indicative of compromised antioxidant defenses. MDA levels increased, and NOx levels decreased, suggesting oxidative stress and impaired vascular function. Lipid profile alterations, including increased triglycerides and total cholesterol, were observed in serum. Elevated levels of inflammatory cytokines (IL-6 and TNF-alpha) further indicated an inflammatory response (p = 0.007, p = 0.018 respectively). GTE administration demonstrated a protective role, restoring antioxidant enzyme levels, suppressing lipid peroxidation, and improving NOx levels.

CONCLUSION

These findings suggest the therapeutic potential of GTE in alleviating the cardiovascular impairments of chronic REM sleep deprivation, emphasizing its candidacy for further clinical exploration as a natural intervention in sleep-related disorders and associated cardiovascular risks.

PON1 rs662, rs854560 and TRIB1 rs17321515, rs2954029 Gene Polymorphisms Are Associated with Lipid Parameters in Patients with Unstable Angina

Acute coronary heart disease (CHD) is mainly caused by the rupture of an unstable atherosclerotic plaque. Many different factors can cause stenosis or even occlusion of the coronary artery lumen, such as vasculitis and platelet aggregation. Our study was performed to assess the association between PON1 rs662, rs854560 and TRIB1 rs17321515, rs2954029 polymorphisms and the risk of CHD, as well as the association between studied polymorphisms and selected clinical parameters affecting the risk of developing ischemic heart disease. A total of 232 patients with unstable angina were enrolled in this study. There were no statistically significant differences in the PON1 rs662, rs854560 and TRIB1 rs17321515, rs2954029 polymorphism distributions between the total study and control groups. Total cholesterol plasma levels were significantly higher in patients with the PON1 rs662 TT genotype compared to those with the CC+TC genotypes, as well as in patients with the PON1 rs854560 TT genotype compared to those with the AA+AT genotypes. LDL plasma levels were significantly increased in patients with the PON1 rs854560 TT genotype compared to those with the AA+AT genotypes. Plasma levels of HDL were significantly decreased in patients with the TRIB1 rs17321515 AA+AG genotypes compared to those with the GG genotype, as well as in patients with the TRIB1 rs2954029 AA+AT genotypes compared to those with the TT genotype. Our results suggest that the analysed polymorphisms are not risk factors for unstable angina in the Polish population. However, the results of this study indicate an association between the PON1 rs662, rs854560 and TRIB1 rs17321515, rs2954029 polymorphisms with lipid parameters in patients with coronary artery disease.

Identification of novel biomarkers in the early diagnosis of malignant melanoma by untargeted liquid chromatography coupled to high-resolution mass spectrometry-based metabolomics: a pilot study

BACKGROUND

Malignant melanoma (MM) is a highly aggressive form of skin cancer whose incidence continues to rise worldwide. If diagnosed at an early stage, it has an excellent prognosis, but mortality increases significantly at advanced stages after distant spread. Unfortunately, early detection of aggressive melanoma remains a challenge.

OBJECTIVES

To identify novel blood-circulating biomarkers that may be useful in the diagnosis of MM to guide patient counselling and appropriate disease management.

METHODS

In this study, 105 serum samples from 26 healthy patients and 79 with MM were analysed using an untargeted approach by liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) to compare the metabolomic profiles of both conditions. Resulting data were subjected to both univariate and multivariate statistical analysis to select robust biomarkers. The classification model obtained from this analysis was further validated with an independent cohort of 12 patients with stage I MM.

RESULTS

We successfully identified several lipidic metabolites differentially expressed in patients with stage I MM vs. healthy controls. Three of these metabolites were used to develop a classification model, which exhibited exceptional precision (0.92) and accuracy (0.94) when validated on an independent sample.

CONCLUSIONS

These results demonstrate that metabolomics using LC-HRMS is a powerful tool to identify and quantify metabolites in bodily fluids that could serve as potential early diagnostic markers for MM.

Paraoxonase 1 gene polymorphisms in lipid oxidation and atherosclerosis development

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

Diabetic retinopathy among type 2 diabetes mellitus patients in Sabah primary health clinics–Addressing the underlying factors

Every person diagnosed with diabetes mellitus (T2DM) is at risk of developing Diabetic retinopathy (DR). Thus, DR is one of the major chronic microvascular complications of T2DM. However, in Malaysia, research about DR is still scarce. This study aimed to determine the prevalence of DR among diabetic patients across 46 primary healthcare clinics in Sabah, Malaysia. Secondly, it purported to identify the factors influencing the development of DR. This cross-sectional study involved a total of 22,345 Type 2 diabetes mellitus (T2DM) patients in the Sabah Diabetic Registry from 2008 to 2015. Of the 22,345 T2DM patients, 13.5% (n = 3,029) of them were diagnosed with DR. Multiple logistic regression revealed seven major risk factors of DR, i.e. patients with diabetic foot ulcer [aOR: 95% CI 3.08 (1.96–4.85)], patients with diabetic nephropathy [aOR: 95% CI 2.47 (2.13–2.86)], hypertension [aOR: 95% CI 1.63 (1.43–1.87)], dyslipidaemia [aOR: 95% CI 1.30 (1.17–1.44)], glycated haemoglobin [(HbA1c) > 6.5 (aOR: 95% CI 1.25 (1.14–1.38)], duration of diabetes mellitus (T2DM) [aOR: 95% CI 1.06 (1.05–1.07)] and age of patient [aOR: 95% CI 1.01 (1.00–1.02)] respectively. DR is a preventable complication. The effective glycaemic control is crucial in preventing DR. In minimizing the prevalence of DR, the healthcare authorities should institute programmes to induce awareness on the management of DR’s risk factors among patient and practitioner.

Characterization of the Structural Diversity and Structure-Specific Behavior of Oxidized Phospholipids by LC-MS/MS

Polyunsaturated fatty acids (PUFAs), esterified to phospholipids, are susceptible to oxidation. They form oxidized phospholipids (OxPLs) by oxygenases or reactive oxygen species (ROS), or both. These OxPLs are associated with various diseases, such as atherosclerosis, pulmonary injuries, neurodegenerative diseases, cancer, and diabetes. Since many types of OxPLs seem to be generated in vivo, precise determination of their structural diversity is required to understand their potential structure-specific functions. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a powerful method to quantitatively measure the structural diversity of OxPLs present in biological samples. This review outlines recent advances in analytical methods for OxPLs and their physiological relevance in health and diseases.

Bioactive Foods and Medicinal Plants for Cardiovascular Complications of Type II Diabetes: Current Clinical Evidence and Future Perspectives

Cardiovascular diseases (CVDs) are the main cause of mortality in type 2 diabetes mellitus (T2DM); however, not all patients are fully satisfied with the current available treatments. Medicinal plants have been globally investigated regarding their effect in CVD, yet the field is far from getting exhausted. The current paper aims to provide an evidence-based review on the clinically evaluated medicinal plants and their main therapeutic targets for the management of CVD in T2DM. Electronic databases including PubMed, Cochrane, Embase, Scopus, and Web of Science were searched from 2000 until November 2019, and related clinical studies were included. Lipid metabolism, glycemic status, systemic inflammation, blood pressure, endothelial function, oxidative stress, and anthropometric parameters are the key points regulated by medicinal plants in T2DM. Anti-inflammatory and antioxidant properties are the two most important mechanisms since inflammation and oxidative stress are the first steps triggering a domino of molecular pathological pathways leading to T2DM and, subsequently, CVD. Polyphenols with potent antioxidant and anti-inflammatory effects, essential oil-derived compounds with vasorelaxant properties, and fibers with demonstrated effects on obesity are the main categories of phytochemicals beneficial for CVD of T2DM. Some medicinal plants such as garlic (Allium sativum) and milk thistle (Silybum marianum) have strong evidences regarding their beneficial effects; however, others have low level of evidence which reveals the need for further clinical studies with larger sample sizes and longer follow-up periods to confirm the safety and efficacy of medicinal plants for the management of CVD in T2DM.

The role of high-density lipoprotein cholesterol, apolipoprotein A and paraoxonase-1 in the pathophysiology of neuroprogressive disorders

Lowered high-density lipoprotein (HDL) cholesterol has been reported in major depressive disorder, bipolar disorder, first episode of psychosis, and schizophrenia. HDL, its major apolipoprotein component, ApoA1, and the antioxidant enzyme paraoxonase (PON)1 (which is normally bound to ApoA1) all have anti-atherogenic, antioxidant, anti-inflammatory, and immunomodulatory roles, which are discussed in this paper. The paper details the pathways mediating the anti-inflammatory effects of HDL, ApoA1 and PON1 and describes the mechanisms leading to compromised HDL and PON1 levels and function in an environment of chronic inflammation. The molecular mechanisms by which changes in HDL, ApoA1 and PON1 might contribute to the pathophysiology of the neuroprogressive disorders are explained. Moreover, the anti-inflammatory actions of ApoM-mediated sphingosine 1-phosphate (S1P) signalling are reviewed as well as the deleterious effects of chronic inflammation and oxidative stress on ApoM/S1P signalling. Finally, therapeutic interventions specifically aimed at improving the levels and function of HDL and PON1 while reducing levels of inflammation and oxidative stress are considered. These include the so-called Mediterranean diet, extra virgin olive oil, polyphenols, flavonoids, isoflavones, pomegranate juice, melatonin and the Mediterranean diet combined with the ketogenic diet.

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.

Reduced oxidized LDL in T2D plaques is associated with a greater statin usage but not with future cardiovascular events

Background

Type 2 diabetes (T2D) patients are at a greater risk of cardiovascular events due to aggravated atherosclerosis. Oxidized LDL (oxLDL) has been shown to be increased in T2D plaques and suggested to contribute to plaque ruptures. Despite intensified statin treatment during the last decade the higher risk for events remains. Here, we explored if intensified statin treatment was associated with reduced oxLDL in T2D plaques and if oxLDL predicts cardiovascular events, to elucidate whether further plaque oxLDL reduction would be a promising therapeutic target.

Methods

Carotid plaque OxLDL levels and plasma lipoproteins were assessed in 200 patients. Plaque oxLDL was located by immunohistochemistry. Plaque cytokines, cells and scavenger receptor gene expression were quantified by Luminex, immunohistochemistry and RNA sequencing, respectively. Clinical information and events during follow-up were obtained from national registers.

Results

Plaque oxLDL levels correlated with markers of inflammatory activity, endothelial activation and plasma LDL cholesterol (r = 0.22-0.32 and p ≤ 0.01 for all). T2D individuals exhibited lower plaque levels of oxLDL, sLOX-1(a marker of endothelial activation) and plasma LDL cholesterol (p = 0.001, p = 0.006 and p = 0.009). No increased gene expression of scavenger receptors was identified in T2D plaques. The lower oxLDL content in T2D plaques was associated with a greater statin usage (p = 0.026). Supporting this, a linear regression model showed that statin treatment was the factor with the strongest association to plaque oxLDL and plasma LDL cholesterol (p < 0.001 for both). However, patients with T2D more frequently suffered from symptoms and yet plaque levels of oxLDL did not predict cardiovascular events in T2D (findings are summarized in Fig. 1a).

Conclusions

This study points out the importance of statin treatment in affecting plaque biology in T2D. It also implies that other biological components, beyond oxLDL, need to be identified and targeted to further reduce the risk of events among T2D patients receiving statin treatment.

The Role of Oxidative Stress in Peripheral Neuropathy

Peripheral neuropathy (PN) is a common disease affecting about 5% of the general population after the age of 50. Causes of PN are numerous and include genetic, diabetes, alcohol, vitamin deficiencies, and gluten sensitivity among others. This systematic review aimed to study the association between oxidative stress and PN in an attempt to better understand PN pathogenesis. A computer-based, systematic search was conducted on the PubMed database, and ensuing data from included articles was analyzed and discussed in this review. Sixty-nine papers were eligible and were used for this review. Peripheral neuropathy is associated with an increase of reactive oxygen species and a decrease in endogenous antioxidants. Genetic predisposition to oxidative damage may be a factor. Antioxidant treatment is promising regarding treatment. Though further research is necessary to better understand the underlying mechanism, it is evident that oxidative stress is implicated in the pathogenesis of - or is at least systematically present in - PN.

Protective Effect of Ginkgolic Acid in Attenuating LDL Induced Inflammation Human Peripheral Blood Mononuclear Cells via Altering the NF-κB Signaling Pathway

Oxidized low-density lipoprotein (ox-LDL) is considered as the significant maker of inflammatory reaction. ox-LDL was reported to play a crucial role in the pathogenesis of atherosclerosis (AS). In the current study, we scrutinize the suppressive effect of ginkgolic acid against ox-LDL induced an oxidative and inflammatory response in human microvascular endothelial cells (HMEC-1) and human peripheral blood mononuclear cells (nPBMCs) and explore the mechanism of action. HMEC-1 cells are treated with ox-LDL in the presence of different concentration of ginkgolic acid. MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was performed for the estimation of cell viability effect. Reactive oxygen species (ROS), inflammatory cytokines, and NF-κB activity are also estimated. For the hPBMCs assay, the cells were isolated from the healthy volunteers and cultured. The cells were further divided into different group and received the ginkgolic acid. Additionally, ROS, inflammatory marker such as prostaglandin E2 (PGE2), lipoxygenase (LOX), nitric oxide (NO), cyclooxygenase (COX) protein expression, and mRNA expression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and vascular cell adhesion protein 1 (VCAM-1) were estimated in the ox-LDL treated group. The result exhibited that ginkgolic acid treatment induced the cell viability boosting in ox-LDL treatment and intracellular ROS significantly decreased by ginkgolic acid. Pro-inflammatory cytokines also downregulated via ginkgolic acid. Moreover, ginkgolic acid reduced the ox-LDL-induced NF-κB. The mRNA and protein expression of TNF-α, IL-6, and VCAM-1 considerably increased in the ox-LDL treated group and ginkgolic acid significantly reduced the mRNA and protein expression. An inflammatory marker such as PGE2, LOX, and NO were increased in the ox-LDL treated group and ginkgolic acid treated group exhibited the reduction of an inflammatory marker. Based on the result, we can conclude that ginkgolic acid significantly reduced and reversed the ox-LDL-induced modulation, suggesting its anti-inflammatory effect via the NF-κB pathway.

Co-ingestion of Antioxidant Drinks With an Unhealthy Challenge Meal Fails to Prevent Post-prandial Endothelial Dysfunction: An Open-Label, Crossover Study in Older Overweight Volunteers

Eating a high calorie meal is known to induce endothelial dysfunction and it is reported that consuming drinks rich in antioxidants may be protective against this. In this study we assessed the effects of three antioxidant drinks with considerable disparity in their antioxidant content on endothelial function. Seven apparently healthy overweight and older adults (BMI 25-35; mean age 57 ± 3 years; one male, six females) completed four trials in a randomized counterbalanced design. Water (control), orange juice, green tea, or red wine were consumed with a high calorie meal (>900 kcal). Endothelial function was measured by flow-mediated dilatation immediately before (fasted, baseline) and 2 h after the meal. Blood samples were also obtained for lipid and glucose analysis, plasma nitrite ( NO 2 - ) and oxidized low-density lipoprotein (ox-LDL). Participants returned after a minimum 3 days washout to complete the remaining arms of the study. The results found that the high calorie meal induced a substantial increase in triglycerides, but not cholesterol or glucose, at 2 h after meal ingestion. FMD was significantly reduced by ∼35% at this timepoint, but the effect was not attenuated by co-ingestion of any of the antioxidant drinks. Reduced FMD was mirrored by a reduction in NO 2 - , but ox-LDL was not increased at 2 h after the meal. None of the undertaken measures were influenced by the antioxidant drinks. We conclude that co-ingestion of none of our test antioxidant drinks protected against the substantial post-prandial endothelial dysfunction induced by an unhealthy meal challenge in our sample population at a 2 h timepoint.

Paraoxonase 1 gene (Q192R) polymorphism confers susceptibility to coronary artery disease in type 2 diabetes patients: Evidence from case-control studies

Numerous published studies have investigated the relationship between the paraoxonase 1 (PON1) gene Q192R (rs662) polymorphism and the risk of coronary artery disease (CAD) in type 2 diabetes mellitus (T2DM) patients. However, the results are still conflicting and inconclusive. Potentially eligible articles were searched for in related databases. Odds ratios (OR) with 95% confidence intervals (CI) were used to estimate the associations. Subgroup analysis was performed based on ethnicity. Ten case-control studies were included. A significant increase in the susceptibility for CAD in T2DM patients was found in the allelic model (OR = 1.49, p < 0.001), homozygote model (OR = 2.47, p < 0.001), heterozygote model (OR = 1.47, p < 0.001), dominant model (OR = 1.64, p < 0.001), and recessive model (OR = 1.74, p = 0.001). In subgroup analysis by ethnicity, a significant increase susceptibility was found in Asian populations in the allelic model (OR = 1.39, p = 0.001), homozygote model (OR = 2.15, p = 0.002), heterozygote model (OR = 1.37, p = 0.006), recessive model (OR = 1.65, p = 0.012), and dominant model (OR = 1.54, p < 0.001). A similar significant increase in susceptibility was found in Caucasian populations in the allelic model (OR = 1.75, p = 0.002), homozygote model (OR = 3.39, p = 0.002), recessive model (OR = 1.98, p = 0.030), heterozygote model (OR = 1.64, p = 0.001), and dominant model (OR = 1.83, p < 0.001). The results suggest that the PON1 Q192R polymorphism is associated with a significantly increased risk of CAD in T2DM patients in both Asian and Caucasian populations.

Serum paraoxonase (a high-density lipoprotein-associated lipophilic antioxidant) activity in clinical follow-up of patients with acute pancreatitis, with particular emphasis on oxidative stress parameters and lipid profile: a prospective pilot trial

The purpose of this study was to investigate the possible role of PON-1, an antioxidant lipophilic enzyme linked to HDL-C (high-density lipoprotein cholesterol), on the pathophysiology and clinical follow-up of acute pancreatitis. Biochemical tests, PON-1 and oxidative stress parameters (malonyl dialdehyde, MDA; superoxide dismutase, SOD; total antioxidant capacity, TAC) were evaluated in the sera of patients with acute pancreatitis at admission (day 0), day 3 and day 10 of follow-up, between June and September 2017. SPSS 13.0 statistical software package programme was used for statistical analyses.Mean age was 51.4 of the total 25 patients. Ranson scores were 0-1 points (60%), 3-4 points (24%) and 5-6 points (16%). CTSI (computed tomography severity index) scores were calculated, and most of the patients were seen to have mild or average pancreatitis (96%). While total cholesterol, triacylglycerol and LDL-C (low-density lipoprotein) levels stayed in their normal limits, there was a significant decrement tendency. HDL-C level was seen to rise significantly above its upper limit at day 10 (p < 0.001). Mean PON-1 levels were measured as 69.23, 76.72 vs. 113.15 U/mL at days 0, 3 and 10, respectively; and it was positively correlated with HDL-C (p < 0.001). Serum SOD increased also in parallel with PON-1 (20.49 vs. 39.46 U/mL) while MDA level decreased significantly (3.9 vs. 2.28 μM, p < 0.001). TAC was seen to rise significantly after treatment (0.52 vs. 1.22 mM). In conclusion, decreased PON-1 and HDL-C together with antioxidants SOD and TAC at the early period of acute pancreatitis were seen to rise after treatment, while the previously higher MDA level decreased in parallel. This reveals the importance of the balance between oxidative stress and antioxidant defense mechanisms in clinical progression of the disease, and the potential of PON-1 as a promising clinical marker.

Supplementation with Hydroxytyrosol and Punicalagin Improves Early Atherosclerosis Markers Involved in the Asymptomatic Phase of Atherosclerosis in the Adult Population: A Randomized, Placebo-Controlled, Crossover Trial

Hydroxytyrosol (HT) and Punicalagin (PC) exert cardioprotective and anti-atherosclerotic effects. This study evaluates the effect of oral supplementation with HT and PC (SAx) on early atherosclerosis markers in middle-aged, seemingly healthy adults. A randomized, double-blinded, placebo-controlled, crossover trial was performed for 20 weeks. There were two treatment sequences (Placebo/SAx, n = 41; SAx/Placebo, n = 43) for which the intervention periods (Placebo and SAx) were 8 weeks long, followed by a 4-week wash out period. The supplement was composed of 9.9 mg of HT and 195 mg of PC, and the placebo was composed of maltodextrin. SAx increased endothelial function (Flow-mediated dilatation [FMD]: 2.36%; p < 0.001) in the endothelial dysfunction subgroup compared to the placebo (2.36 ± 3.9 vs. 0.76 ± 3.5%, p < 0.05). SAx also reduced oxLDL by -28.74 ng/mL (p < 0.05) in subjects with higher levels of oxLDL, which was an improvement compared with the placebo (-28.74 ± 40.2 vs. 25.64 ± 93.8 ng/mL, p < 0.001). The prehypertension and hypertension subgroups exhibited decreased systolic (-15.75 ± 9.9 mmHg; p < 0.001) and diastolic (-6.36 ± 8.7 mmHg; p < 0.001) blood pressure after SAx consumption. Moreover, the systolic prehypertension and hypertension subgroups presented significant differences in systolic blood pressure compared to the placebo (-15.75 ± 9.9 vs. -2.67 ± 12.0 mmHg, p < 0.05). In conclusion, the supplement exerted anti-atherosclerotic effects by improving endothelial function, blood pressure, and levels of circulating oxLDL, especially for persons in whom these parameters were altered.

The Association between Genomic DNA Methylation and Diabetic Peripheral Neuropathy in Patients with Type 2 Diabetes Mellitus

AIM

DNA methylation is thought to be involved in regulating the expression of key genes and inducing diabetic peripheral neuropathy (DPN). However, clinically, the level of whole-genome DNA methylation and its relationship with DPN remains unclear.

METHODS

186 patients with type 2 diabetes mellitus (T2DM) admitted to the Second Affiliated Hospital of Soochow University since Jul. 2016 to Oct. 2017 were enrolled in the study, including 100 patients in the DPN group and 86 patients in the non-DPN group, diagnosed with Toronto Clinical Scoring System (TCSS). Clinical and biochemical characteristics between the two groups were compared, and the correlations with TCSS scores were analyzed. Furthermore, the levels of genomic DNA methylation of leukocytes, measured with high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS), were also analyzed between the two groups.

RESULTS

Age, duration, triglyceride (TG), total cholesterol (TC), low-density lipoprotein (LDL-C), creatinine, uric acid (UA), blood urea nitrogen (BUN), and C-reactive protein (CRP) were significantly higher in the DPN group. Estimated glomerular filtration rate (eGFR) and the level of genomic DNA methylation were much lower in the DPN group. Spearman correlation analysis showed that TCSS was positively correlated with age, duration, UA, and CRP and was negatively correlated with body mass index (BMI), eGFR, and the level of genomic DNA methylation. Interestingly, multiple stepwise regression analysis showed that only duration, genomic DNA methylation, and eGFR had impacts on TCSS. The results also showed that the levels of genomic DNA methylation did not change significantly whether or not there was renal injury. Another multiple stepwise regression analysis showed that TCSS and BMI were the influencing factors of genomic DNA methylation. Finally, we found that genomic DNA methylation levels were decreased significantly in the DPN group compared with the non-DPN group when the duration is ≥5 years or BMI ≥ 25 kg/m².

CONCLUSION

Low level of genomic DNA methylation is a relative specific risk factor of diabetic peripheral neuropathy in patients with type 2 diabetes.

Diabetic dyslipidaemia is associated with alterations in eNOS, caveolin-1, and endothelial dysfunction in streptozotocin treated rats

BACKGROUND

Diabetes is a complex progressive disease characterized by chronic hyperglycaemia and dyslipidaemia associated with endothelial dysfunction. Oxidized LDL (Ox-LDL) is elevated in diabetes and may contribute to endothelial dysfunction. The aim of this study was to relate the serum levels of Ox-LDL with endothelial dysfunction in streptozotocin (STZ)-diabetic rats and to further explore the changes in endothelial nitric oxide synthase (eNOS) and caveolin-1 (CAV-1) expression in primary aortic endothelial cells.

METHODS

Diabetes was induced with a single intraperitoneal injection of STZ in male Wistar rats. During the hyperglycaemic diabetes state serum lipid markers, aortic relaxation and aortic endothelial cell eNOS and CAV-1 protein expressions were measured.

RESULTS

Elevated serum Ox-LDL (STZ 1486 ± 78.1 pg/mL vs control 732.6 ± 160.6 pg/mL, P < .05) was associated with hyperglycaemia (STZ 29 ± 0.9 mmol/L vs control: 7.2 ± 0.2 mmol/L, P < .001) and hypertriglyceridaemia (STZ 9.0 ± 1.5 mmol/L vs control: 3.0 ± 0.3 mmol/L, P < .01) in diabetic rats. A significant reduction was observed in STZ-diabetic aortic endothelial cell eNOS and CAV-1 of 40% and 30%, respectively, accompanied by a compromised STZ-diabetic carbachol-induced vasodilation (STZ 29.6 ± 9.3% vs control 77.2 ± 2.5%, P < .001).

CONCLUSIONS

The elevated serum Ox-LDL in hyperglycaemic STZ-diabetic rats may contribute to diabetic endothelial dysfunction, possibly through downregulation of endothelial CAV-1 and eNOS.

Efficiencies of Low-Level Laser Therapy (LLLT) and Gabapentin in the Management of Peripheral Neuropathy: Diabetic Neuropathy

Diabetic neuropathy (DN) is the highly occurred complication of diabetes mellitus; it has been defined as an event of peripheral nerve dysfunction characterized by pain, allodynia, hyperalgesia, and paraesthesia. The current study was conducted to evaluate the efficacy of low-level laser therapy (LLLT) in the management of neuropathy in diabetic rats. The used animals were divided into the following groups: negative control, streptozotocin-induced diabetic rats, and diabetic rats with peripheral neuropathy (DNP) and DNP treated with gabapentin or with LLLT. Behavioral tests were carried out through hotplate test for the determination of pain sensations and the Morris water maze test for spatial reference memory evaluation. Blood samples were collected at the end of treatment for biochemical determinations. In the current study, the latency of hind-paw lick decreased significantly when DNP are treated with gabapentin or LLLT. The Morris water maze test showed that LLLT treatment improved memory that deteriorated in DNP more than gabapentin do. The results of the biochemical study revealed that LLLT could not affect the level of beta-endorphin that decreased in DNP but significantly decreased S100B that rose in DNP. PGE2 and cytokines IL-1β, IL-10, and TNF-α showed significant increase in DNP compared with control group. The gabapentin administration or LLLT application significantly reversed the levels of the mentioned markers towards the normal values of the controls. Levels of serum MDA and nitric oxide increased significantly in the DNP but rGSH showed significant decrease. These markers were improved significantly when the DNP were treated with gabapentin or LLLT. The treatment with gabapentin or LLLT significantly decreased the raised level in total cholesterol in DNP but could not decrease the elevated level of triglycerides, while LDL cholesterol decreased significantly in DNP treated with gabapentin but not affected by LLLT. Values of serum alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), urea, and creatinine increased significantly in the DPN and diabetic rats without peripheral neuropathy (PN) compared with control group. The treatment of DNP with gabapentin induced significant increases in ALAT and ASAT activities but LLLT treatment induced significant decreases in ALAT and ASAT activities as compared with DNP group. Neither gabapentin nor LLLT could improve the elevated levels of serum urea and creatinine in the DNP. It could be concluded that LLLT is more safe and effective than gabapentin in the management of neuropathy in diabetic rats.

The relationship between oxidized low-density lipoprotein and the NIHSS score among patients with acute ischemic stroke: The SOS-Stroke Study

BACKGROUND AND AIMS

Oxidized low-density lipoprotein (oxLDL) has a defined role in the genesis and development of atherosclerosis, however, whether it is related to severity of neurological deficits is rarely reported. The aim of our study was to investigate the potential association between oxLDL and the National Institutes of Health Stroke Scale (NIHSS) score among patients with acute ischemic stroke.

METHODS

Between January 2014 and October 2014, we recruited 4111 patients with acute ischemic stroke (AIS), who were admitted within 7 days-43 hospitals in China, and participated in the SOS-Stroke Study. We collected detailed clinical data and then tested the relationship between oxLDL and the NIHSS score using a multivariate linear regression analysis.

RESULTS

After adjusting for age, gender, ethnicity, marriage and other confounding variables, the elevated NIHSS score was significantly associated with increased oxLDL levels, and each 1-μg/dL elevation in oxLDL concentration resulted in an increase of 0.027 in the NIHSS score.

CONCLUSIONS

A positive correlation was found between plasma levels of oxLDL and the NIHSS score in patients with acute ischemic stroke. Higher plasma levels of oxLDL potentially suggest a worse prognosis in AIS patients.

Comprehensive analyses of oxidized phospholipids using a measured MS/MS spectra library

Oxidized phospholipids (OxPLs) are widely held to be associated with various diseases, such as arteriosclerosis, diabetes, and cancer. To characterize the structure-specific behavior of OxPLs and their physiological relevance, we developed a comprehensive analytical method by establishing a measured MS/MS spectra library of OxPLs. Biogenic OxPLs were prepared by the addition of specific oxidized fatty acids to cultured cells, where they were incorporated into cellular phospholipids, and untargeted lipidomics by LC-quadrupole/TOF-MS was applied to collect MS/MS spectra for the OxPLs. Based on the measured MS/MS spectra for about 400 molecular species of the biogenic OxPLs, we developed a broad-targeted lipidomics system using triple quadrupole MS. Separation precision of structural isomers was optimized by multiple reaction monitoring analysis and this system enabled us to detect OxPLs at levels as low as 10 fmol. When applied to biological samples, i.e., mouse peritoneal macrophages, this system enabled us to monitor a series of OxPLs endogenously produced in a 12/15-lipoxygenase-dependent manner. This advanced analytical method will be useful to elucidate the structure-specific behavior of OxPLs and their physiological relevance in vivo.

Glycation of paraoxonase 1 by high glucose instigates endoplasmic reticulum stress to induce endothelial dysfunction in vivo

High-density lipoprotein (HDL) modulates low-density lipoprotein and cell membrane oxidation through the action of paraoxonase-1 (PON1). Endoplasmic reticulum (ER) stress has been linked to a wide range of human pathologies including diabetes, obesity, and atherosclerosis. Previous studies have reported that PON1 is glycated in diabetes. The aim of this study is to investigate whether and how PON1 glycation contributes to endothelial dysfunction in diabetes. ER stress markers were monitored by western blot. Endothelial function was determined by organ bath. Incubation of recombinant PON1 proteins with high glucose increased PON1 glycation and reduced PON1 activity. Exposure of HUVECs to glycated PON1 induced prolonged ER stress and reduced SERCA activity, which were abolished by tempol, apocynin, BAPTA, and p67 and p22 siRNAs. Chronic administration of amino guanidine or 4-PBA prevented endothelial dysfunction in STZ-injected rats. Importantly, injection of glycated PON1 but not native PON1 induced aberrant ER stress and endothelial dysfunction in rats, which were attenuated by tempol, BAPTA, and 4-PBA. In conclusion, glycation of PON1 by hyperglycemia induces endothelial dysfunction through ER stress. In perspectives, PON1 glycation is a novel risk factor of hyperglycemia-induced endothelial dysfunction. Therefore, inhibition of oxidative stress, chelating intracellular Ca²⁺, and ER chaperone would be considered to reduce vascular complications in diabetes.

Pro198Leu Polymorphism in the Glutathione Peroxidase 1 Gene Contributes to Diabetic Peripheral Neuropathy in Type 2 Diabetes Patients

Glutathione peroxidase 1 (Gpx1) is an endogenous antioxidant enzyme. The T allele of the Pro198Leu polymorphism in the Gpx1 (rs1050450, 198C > T) gene is associated with reduced enzyme activity. The aim of this study was to evaluate the association between Pro198Leu polymorphism and risk of diabetic peripheral neuropathy (DPN). We examined 1244 T2DM patients and 730 healthy controls. In the patient group, 33 % had diabetic peripheral neuropathy. All subjects were genotyped for the Gpx1 Pro198Leu polymorphism by polymerase chain reaction and restriction analysis. A significant increase in the T allele and TT genotype frequencies was observed in DPN patients compared to those without DPN (OR 1.55, 95 % CI 1.30-1.85 and 1.89, 95 % CI 1.30-2.74, respectively). The association remained significant after correction for age, disease duration, HbA1c and BMI. When distribution of T allele was compared between DPN+ and DPN- subgroups and controls, OR was 1.54 for DPN+ and 1.00 for DPN- patients. In conclusion, our findings suggest that Gpx1 Pro198Leu genotypes are significantly associated with the risk of diabetic peripheral neuropathy in patients with T2DM. The study provides new clinically relevant information regarding genetic determinants of susceptibility to diabetic neuropathy.

Dietary marine-derived long-chain monounsaturated fatty acids and cardiovascular disease risk: a mini review

Regular fish/fish oil consumption is widely recommended for protection against cardiovascular diseases (CVD). Fish and other marine life are rich sources of the cardioprotective long-chain n-3 polyunsaturated fatty acids (n-3 PUFA) eicosapentaenoic acid (C20:5 n-3; EPA) and docosahexaenoic acid (C22:6 n-3; DHA). The lipid content and fatty acid profile of fish, however, vary greatly among different fish species. In addition to n-3 PUFA, certain fish, such as saury, pollock, and herring, also contain high levels of long-chain monounsaturated fatty acids (LCMUFA), with aliphatic tails longer than 18 C atoms (i.e., C20:1 and C22:1 isomers). Compared with well-studied n-3 PUFA, limited information, however, is available on the health benefits of marine-derived LCMUFA, particularly in regard to CVD. Our objective in this review is to summarize the current knowledge and provide perspective on the potential therapeutic value of dietary LCMUFA-rich marine oil for improving CVD risk factors. We will also review the possible mechanisms of LCMUFA action on target tissues. Finally, we describe the epidemiologic data and small-scaled clinical studies that have been done on marine oils enriched in LCMUFA. Although there are still many unanswered questions about LCMUFA, this appears to be promising new area of research that may lead to new insights into the health benefits of a different component of fish oils besides n-3 PUFA.

Effects of pomegranate juice consumption on oxidative stress in patients with type 2 diabetes: a single-blind, randomized clinical trial

Increased free radicals production due to hyperglycemia produces oxidative stress in patients with diabetes. Pomegranate juice (PJ) has antioxidant properties. This study was conducted to determine the effects of PJ consumption in oxidative stress in type 2 diabetic patients. This study was a randomized clinical trial performed on 60, 40-65 years old diabetic patients. The patients were randomly allocated either to PJ consumption group or control. Patients in PJ group consumed 200 ml of PJ daily for six weeks. Sex distribution and the mean age were not different between two groups. After six weeks intervention, oxidized LDL and anti-oxidized LDL antibodies decreased and total serum antioxidant capacity and arylesterase activity of paraoxonase increased significantly in the PJ-treated group compared to the control group. Our data have shown that six weeks supplementation of PJ could have favorable effects on oxidative stress in patients with type 2 diabetes (T2D).

C‑reactive protein/oxidized low density lipoprotein/β2‑glycoprotein i complexes induce lipid accumulation and inflammatory reaction in macrophages via p38/mitogen‑activated protein kinase and nuclear factor‑κB signaling pathways

Oxidized low-density lipoprotein (oxLDL) can bind to β2-glycoprotein I (β2GPI) and C-reactive protein (CRP) to form stable complexes, which exert certain effects in diabetic cardiovascular disease. A previous study by our group has confirmed that the resulting complexes promote atherosclerosis in diabetic BALB/c mice. The present study was designed to investigate the effects and potential mechanisms of oxLDL complexes on lipid accumulation and inflammatory reactions in RAW264.7 macrophages cultured in a hyperglycemic environment. Cultured cells were divided into seven groups, which were treated with phosphate‑buffered saline (control), CRP, β2GPI, oxLDL, CRP/oxLDL, oxLDL/β2GPI or CRP/oxLDL/β2GPI. The results revealed the formation of foam cells in the oxLDL, CRP/oxLDL, oxLDL/β2GPI as well as CRP/oxLDL/β2GPI groups. Compared with oxLDL, the three complexes induced less lipid accumulation (P<0.05) through inhibiting the expression of CD36 mRNA and promoting the expression of and ABCG1 mRNA (P<0.05 vs. oxLDL). Furthermore, the levels of inflammatory factors interleukin (IL)‑1β, IL‑6 and tumor necrosis factor‑α were elevated in the CRP/oxLDL and CRP/oxLDL/β2GPI groups (P>0.05 vs. oxLDL), and obvious effects on p38/mitogen‑activated protein kinase and nuclear factor (NF)‑κB phosphorylation were also observed in these groups (P<0.05 vs. oxLDL). These results suggested that CRP/oxLDL/βG2P1 complexes may induce lipid accumulation and inflammation in macrophages via the p38/MAPK and NF‑κB signaling pathways. However, some differences were observed between the complexes, which may be attributed to the property of each constituent; therefore, further studies are required.

Biochemical effects, hypolipidemic and anti-inflammatory activities of Artemisia vulgaris extract in hypercholesterolemic rats

The purpose of the present study was to investigate hypolipidemic and anti-inflammatory effects of Artemisia vulgaris extract in hypercholesterolemic rats. Hypercholesterolemia was induced by feeding of rats with high fat diet containing 3% cholesterol in olein oil, for 8 weeks. Feeding of rats with high fat diet for 8 weeks, leading to a significant increase in serum triglycerides, total cholesterol, low density lipoprotein cholesterol, malondialdehyde and nitric oxide, tumor necrosis factor-α levels and a significant decrease in serum high density lipoprotein cholesterol level, liver hydroxymethylglutaryl-CoA reductase activity and paraoxonase-1 activities as compared to the normal control group. Treatment of high fat diet rats with Artemisia vulgaris extract for 4 weeks at a dose of 100 mg/kg per day, resulted in normalized serum lipid profile, a significant increase in paraoxonase-1 activity and decrease in serum malondialdehyde, nitric oxide and tumor necrosis factor-α level as compared to high fat diet-treated animals. Also the extract caused a significant decrease in hydroxymethylglutaryl-CoA reductase activity as compared with both high fat diet-treated animals and control ones. In conclusion, Artemisia vulgaris extract has hypolipidemic, anti-inflammatory, antioxidant properties; it may serve as a source for the prevention of atherosclerosis and cardiovascular diseases.

Biochemical effects, hypolipidemic and anti-inflammatory activities of Artemisia vulgaris extract in hypercholesterolemic rats

The purpose of the present study was to investigate hypolipidemic and anti-inflammatory effects of Artemisia vulgaris extract in hypercholesterolemic rats. Hypercholesterolemia was induced by feeding of rats with high fat diet containing 3% cholesterol in olein oil, for 8 weeks. Feeding of rats with high fat diet for 8 weeks, leading to a significant increase in serum triglycerides, total cholesterol, low density lipoprotein cholesterol, malondialdehyde and nitric oxide, tumor necrosis factor-α levels and a significant decrease in serum high density lipoprotein cholesterol level, liver hydroxymethylglutaryl-CoA reductase activity and paraoxonase-1 activities as compared to the normal control group. Treatment of high fat diet rats with Artemisia vulgaris extract for 4 weeks at a dose of 100 mg/kg per day, resulted in normalized serum lipid profile, a significant increase in paraoxonase-1 activity and decrease in serum malondialdehyde, nitric oxide and tumor necrosis factor-α level as compared to high fat diet-treated animals. Also the extract caused a significant decrease in hydroxymethylglutaryl-CoA reductase activity as compared with both high fat diet-treated animals and control ones. In conclusion, Artemisia vulgaris extract has hypolipidemic, anti-inflammatory, antioxidant properties; it may serve as a source for the prevention of atherosclerosis and cardiovascular diseases.

Nitrosative stress but not glycemic parameters correlate with improved neuropathy in nonseverely obese diabetic patients after Roux-Y gastric bypass

BACKGROUND

Diabetic neuropathy is common in type 2 diabetic patients (T2DM) but tight glycemic control does not improve the symptoms. In contrast, Roux-Y gastric bypass (RYGB) has a positive effect on active neuropathic symptoms, independent from glycemic control. The purpose of the present study was to identify potential mechanisms of improved diabetic neuropathic symptoms after RYGB.

METHODS

A prospective cohort of 20 patients with insulin-dependent T2DM and BMI < 35 kg/m(2) were treated with RYGB. Nineteen patients had complete follow-up. Fasting glucose, HbA1c (glycated hemoglobin), markers for nitrosative, carbonyl, and oxidative stress (nitrotyrosine, carboxylated-lysine (CML), methylglyoxal, oxidized low-density-lipoprotein (oxLDL)) as well as Neuropeptid Y and Neurokinin A were investigated over 12 months. Neuropathy was assessed using the Neuropathy Deficit Score (NDS).

RESULTS

The preoperative NDS improved within twelve months (5.1 ± 0.6 to 2.6 ± 0.4, P = .010). Fasting glucose and HbA1c also improved compared to preoperative values (201.1 ± 16.6 mg/dL to 128 ± 8.7 mg/dL, P = .004 and 8.5 ± 0.3% (53 ± 3.3 mmol/mol) to 7 ± 0.3% (67 ± 3.3 mmol/mol), P = .001, respectively). Nitrotyrosine, CML, and methylglyoxal all 3 decreased postoperatively (1067.3 ± 266.9 nM to 355.8 ± 36.4 nM, P = .003; 257.1 ± 10.2 ng/ml to 215.3 ± 18.3 ng/ml, P = .039; 402.3 ± 3.9 nM to 163.4 ± 10.3 nM, P = .002). OxLDL remained unchanged. Fasting glucose and HbA1c did not correlate with improved neuropathy. The decrease in nitrotyrosine correlated with improvement in the NDS after 6 and twelve months (r = .9, P < .001 and r = .68, P = .03). The decrease in methylglyoxal after 6 months correlated with decrease in NDS after twelve months (r = 0.897, P = .003).

CONCLUSION

RYGB seems to improve oxidative, nitrosative and carbonyl stress, known to have a causal role in diabetic neuropathy.

Plasma paraoxonase 1 arylesterase activity in D-galactose-induced aged rat model: correlation with LDL oxidation and redox status

OBJECTIVE

There is much evidence linking the involvement of oxidative stress in the pathogenesis of aging. Paraoxonase 1 (PON1) is an HDL-associated antioxidant enzyme that inhibits the oxidative modification of low-density lipoproteins (LDL). We have investigated the changes in plasma PON1 activity, LDL oxidation, radical scavenging activity and lipid peroxidation in D-galactose-induced aging rat model and also compared the results with 24-month naturally aged rats.

METHOD

Arylesterase activity of PON1, susceptibility of LDL for oxidation, plasma radical scavenging activity and plasma thiobarbituric acid reactive substances (TBARS) were measured in normal control rats (4-months-old control rats subjected to D-galactose-induced experimental aging, and 24-month-old naturally aged rats).

RESULTS

There was a significant decrease in plasma PON1 arylesterase activity in both subcutaneous D-galactose-treated groups and 24-month-old aged rats (P < 0.05, for each). TBARS, an oxidative stress marker, was seen to increase in the experimental groups (P < 0.01). In both subcutaneous galactose-treated and naturally aged rats, there was a significant rise in plasma LDL oxidation (P < 0.05, for each). However, radical scavenging activity was decreased significantly (P < 0.01) in both groups, as compared to control.

CONCLUSIONS

The D-galactose-induced rat model of aging mimics the naturally aged rat with reference to PON1 arylesterase activity and susceptibility to LDL oxidation. The results emphasize the importance of PON1 with respect to aging and its association with redox balance of the body.

Serum myeloperoxidase/paraoxonase 1 ratio as potential indicator of dysfunctional high-density lipoprotein and risk stratification in coronary artery disease

OBJECTIVE

Granular leukocyte-derived myeloperoxidase (MPO) promotes oxidation of lipoproteins, while paraoxonase 1 (PON1) has antioxidant properties for high-density lipoprotein (HDL). We evaluated their effects on coronary risk stratification and function of lipoproteins.

METHODS AND RESULTS

A total 158 patients who had previously undergone percutaneous coronary intervention and who had been hospitalized for coronary re-angiography were enrolled. Coronary lesions (restenosis or de novo lesion) were observed in 84 patients but not associated with conventional lipid profile. In contrast, serum MPO levels and PON1 activities were significantly associated with the prevalence of coronary lesions. The high MPO/PON1 ratio, when cutoff values were set at 1.59, was independently correlated with restenosis (odds ratio 6.4, 95% CI 2.2-19.3, P = 0.001) and de novo lesions (odds ratio 3.5, 95% CI 1.3-9.4, P = 0.014). We isolated HDL from patients with high or low MPO/PON1 ratio, and compared anti-inflammatory properties of HDL. Human umbilical vein endothelial cells were stimulated with inflammatory cytokine, and the expression of vascular cell adhesion molecule-1 (VCAM-1) was evaluated. HDL isolated from patients with low serum MPO/PON1 ratio inhibited VCAM-1 expression significantly greater than that with high MPO/PON1 ratio. We also demonstrated that the cholesterol efflux capacity of apolipoprotein B-depleted serum from patients with high MPO/PON1 ratio was significantly decreased than that with low MPO/PON1 ratio.

CONCLUSIONS

MPO/PON1 ratio could be a useful marker for secondary prevention of coronary artery disease through modulation of HDL function.

Association of paraoxonase gene polymorphisms with diabetic nephropathy and retinopathy

Emerging reports have revealed a potential association of paraoxonase (PON) gene polymorphisms with diabetic nephropathy (DN) and diabetic retinopathy (DR). However, the identification of susceptible genes and the quantification of associated risks are elusive owing to a lack of reproducibility. Therefore, a meta‑analysis was conducted in the present study to improve the understanding of the effect of PON1 and PON2 on DN and DR. A total of 10 articles, involving 2,877 patients and 3,246 controls met the inclusion criteria. Functional variants (n=4) were evaluated, including rs662 (p.Q192R) and rs854560 (p.L55M) in PON1; and rs7493 (p.S311C) and rs12026 (p.A148G) in PON2. Overall, PON1‑L55M was found to be significantly associated with DR in all the genetic models: allele [odds ratio (OR)=2.42; 95% confidence interval (CI), 1.91‑3.07]; dominant (OR=5.76; 95% CI, 3.14‑10.55), homozygote (OR=10.53; 95% CI, 5.59‑19.86), heterozygote (OR=3.62; 95% CI, 1.94‑6.74), and recessive (OR=3.56; 95% CI, 2.61‑4.86), with no evidence of between‑study heterogeneity. However, such associations were not detected in DN and the other three polymorphisms did not show any associations with DN or DR. The current meta‑analysis highlighted results for the risk of association of PON1‑55L with DR. The results also indicated that PON2 gene polymorphisms, as well as PON1‑Q192R, may not confer major genetic risk to DN or DR. Additional studies are required to enrich the understanding of PON genes, particularly for its functional role in DR.

Paraoxonase and arylesterase activities, lipid profile, and oxidative damage in experimental ischemic colitis model

Objective. In the present study, since PON1 is known as an HDL-associated antioxidant enzyme that inhibits the oxidative modification of LDL and oxidative stress plays a role in the pathogenesis of mesenteric ischemia, we investigated the changes in PON1 activity and lipid profile in an experimental ischemic colitis model. Methods. Forty male Wistar albino rats were divided into two groups: the control group (N = 15) and the experimental group (N = 25). All animals were anesthetized with ether and ketamine anesthesia to undergo a midline laparotomy. Ischemic colitis was induced by marginal vessel ligation in the splenic flexura (devascularization process). A sham laparotomy was performed in the control group. All animals were sacrificed on the seventh postoperative day. Oxidative stress marker (malonyldialdehyde, MDA), lipid profile, and paraoxonase (PON-1) and arylesterase activities were determined. Histopathological evaluation was done under light microscopy, after sectioning and staining with hematoxyline and eosin. Statistical analysis was conducted using Student's t-test and Mann-Whitney U test, and P < 0.05 was considered as statistically significant. Results. There was a significant decrease in both serum and tissue PON1 activity in ischemic colitis group (P < 0.01, for each). Similarly, arylesterase levels showed a parallel decrease in both tissue and serum of the experimental group (P < 0.01 and P < 0.001, retrospectively). MDA, an oxidative stress marker, was seen to increase in the experimental group (P < 0.01, tissue; P < 0.05, serum). In experimental group, there was a significant rise in serum total cholesterol and LDL levels (P < 0.001, for each). However, HDL level decreased significantly (P < 0.001). Triglycerides did not show any change between the groups (P > 0.05). Conclusions. PON1 and arylesterase play an important role in the pathophysiology of ischemic colitis.

HDL functionality

PURPOSE OF REVIEW

HDL cholesterol concentration is inversely correlated with cardiovascular disease and has a wide range of functions involved in many systems. The purpose of this review is to summarize HDL functionality, its relevance to atherosclerosis and factors affecting HDL functions.

RECENT FINDINGS

The contribution of HDL to reverse cholesterol transport may not be as great as first envisaged. However, it still plays an important role in cholesterol efflux from peripheral tissues. The capacity of HDL to promote cellular cholesterol efflux in an ex-vivo model has been reported to correlate more closely with carotid intima-media thickness than HDL cholesterol concentration. Recently, a variety of other functions of HDL have been described including antimicrobial, antioxidant, antiglycation, anti-inflammatory, nitric oxide--inducing, antithrombotic and antiatherogenic activity and immune modulation as well as a potential role in glucose homeostasis, diabetes pathophysiology and complications.

SUMMARY

HDL has a wide range of functions some of which are independent of its cholesterol content. Its cargo of apolipoproteins, various proteins and phospholipids contributes most to its various functions. These functions are affected by a number of genetic, physiological and pathological factors.

Association between the rs1050450 glutathione peroxidase-1 (C > T) gene variant and peripheral neuropathy in two independent samples of subjects with diabetes mellitus

Glutathione peroxidase-1 (GPx-1) is an endogenous anti-oxidant enzyme. The T allele of the GPx-1 rs1050450 (C > T) gene variant is associated with reduced enzyme activity. Our aim was to examine the association between this gene variant and peripheral neuropathy in two cross-sectional samples of subjects with diabetes: (i) 773 Caucasian subjects were genotyped from the UCL Diabetes and Cardiovascular disease Study (UDACS) and (ii) 382 Caucasian subjects from the Ealing Diabetes Study (EDS). Peripheral neuropathy status (and oxidised-LDL [Ox-LDL:LDL] and plasma Total Ant-ioxidant Status [TAOS] in UDACS), were analysed in relation to genotype. We observed that: (i) In UDACS, the odds ratio (OR) for peripheral neuropathy in the T allele carriers compared to the CC genotype was 1.61 [1.10-2.28], p = 0.01. This remained significant after adjustment for other risk factors. Ox-LDL:LDL ratio was significantly elevated in T allele carriers (CC vs. CT/TT: 16.3 ± 2.4 v 18.0 ± 2.9 U/mmol LDL, p = 0.02). (ii) In EDS, the OR for peripheral neuropathy in the T allele carriers compared to the CC genotype was 1.95 [1.11-3.42], p = 0.02. This remained significant after adjustment for other risk factors. In conclusion, we observed a significant association between the T allele and peripheral neuropathy and LDL oxidation. This is the first paper to examine the rs1050450 variant in two samples of Caucasian subjects with diabetes. Prospective analysis of the gene variant is required in diabetic and healthy cohorts with measured plasma markers of oxidative stress to investigate the described association further.

Comparison of ox-LDL Levels in Diabetic Patients with Normo-, Micro-, and Macroalbuminuria with Their First Degree Relatives and the Healthy Control Group

Oxidized low density lipoprotein (ox-LDL) is a product of oxidative stress. In this cross-sectional study, we compared the ox-LDL concentrations in diabetic patients with normoalbuminuria (n = 28), microalbuminuria (n = 28), and macroalbuminuria (n = 28) with their first degree relatives (n = 28) and healthy control people (n = 31). They were selected by consecutive patient selection method. The ox-LDL level was assayed using ELISA. We measured blood pressure, lipid profile, fasting plasma glucose (FPG), and HbA1c in all groups. There was no significant difference in ox-LDL concentrations among normoalbuminuric, microalbuminuric, and macroalbuminuric diabetic groups. In diabetic patients with micro- and macroalbuminuria, ox-LDL concentration was higher than their first degree relatives (P = 0.04 and P = 0.03) and control group (P = 0.001 and P = 0.03, resp.). In normoalbuminuric diabetic persons, ox-LDL concentration was just higher than that of healthy people (P = 0.02). There was no statistically significant difference in ox-LDL levels between normoalbuminuric diabetic patients and their first degree relatives. In conclusion, the presence and progression of albuminuria in diabetic patients are not related to ox-LDL concentration and genetic predisposition influences the plasma OX-LDL level. Larger sample size is needed to confirm this conclusion in future studies.

Impaired hepatic insulin signalling in PON2-deficient mice: a novel role for the PON2/apoE axis on the macrophage inflammatory response

Hepatic glucose metabolism is strongly influenced by oxidative stress and pro-inflammatory stimuli. PON2 (paraoxonase 2), an enzyme with undefined antioxidant properties, protects against atherosclerosis. PON2-deficient (PON2-def) mice have elevated hepatic oxidative stress coupled with an exacerbated inflammatory response from PON2-deficient macrophages. In the present paper, we demonstrate that PON2 deficiency is associated with inhibitory insulin-mediated phosphorylation of hepatic IRS-1 (insulin receptor substrate-1). Unexpectedly, we observed a marked improvement in the hepatic IRS-1 phosphorylation state in PON2-def/apoE (apolipoprotein E)(-/-) mice, relative to apoE(-/-) mice. Factors secreted from activated macrophage cultures derived from PON2-def and PON2-def/apoE(-/-) mice are sufficient to modulate insulin signalling in cultured hepatocytes in a manner similar to that observed in vivo. We show that the protective effect on insulin signalling in PON2-def/apoE(-/-) mice is directly associated with altered production of macrophage pro-inflammatory mediators, but not elevated intracellular oxidative stress levels. We further present evidence that modulation of the macrophage inflammatory response in PON2-def/apoE(-/-) mice is mediated by a shift in the balance of NO and ONOO(-) (peroxynitrite) formation. Our results demonstrate that PON2 plays an important role in hepatic insulin signalling and underscores the influence of macrophage-mediated inflammatory response on hepatic insulin sensitivity.

CYP2C19 but not PON1 genetic variants influence clopidogrel pharmacokinetics, pharmacodynamics, and clinical efficacy in post-myocardial infarction patients

BACKGROUND

Reduced concentrations of clopidogrel active metabolite have been associated with diminished platelet inhibition and higher rates of adverse cardiovascular events. Paraoxonase-1 (PON1) has recently been proposed as a key enzyme for clopidogrel metabolic activation. We tested the effects of PON1 polymorphisms on clopidogrel pharmacokinetics and pharmacodynamics and the occurrence of cardiovascular outcomes in young post-myocardial infarction (MI) patients treated with clopidogrel.

METHODS AND RESULTS

We genotyped PON1 (Q192R and L55M) and CYP2C19 variants in 106 patients enrolled in the PK/PD CLOVIS-2 trial. Patients were randomly exposed to a 300-mg or 900-mg clopidogrel loading dose in a crossover study design. Clopidogrel active metabolite isomer H4 (clopi-H4) and platelet function testing were measured serially after loading dose. There was no significant association between PON1 Q192R or L55M and clopi-H4 formation or antiplatelet response to clopidogrel after either loading dose. Using multivariable linear regression analyses, the CYP2C19*2 allele was the only predictor of clopi-H4 generation and platelet response irrespective of the platelet function assay. CYP2C19 loss-of-function but not PON1 variants were significantly associated with increased risk of major cardiovascular events (death, MI, and urgent coronary revascularization) occurring during long-term clopidogrel exposure in 371 young post-MI patients (age <45 years) enrolled in the AFIJI cohort (CYP2C19 loss-of-function allele carrier versus noncarrier: hazard ratio, 2.26; 95% confidence interval, 1.15-4.41, P=0.02; PON1 QQ192 versus QR/RR192: hazard ratio, 1.03; 95% confidence interval, 0.50-2.11, P=0.93; PON1 LL55 versus LM/MM55: hazard ratio, 1.52; 95% confidence interval, 0.75-3.08, P=0.24).

CONCLUSIONS

Our study does not confirm that PON1 Q192R or L55M can influence clopidogrel pharmacokinetics or pharmacodynamics in post-MI patients.

Homology modeling of human serum paraoxonase1 and its molecular interaction studies with aspirin and cefazolin

Human serum paraoxonase1 (HuPON1) belongs to the family of A-esterases (EC.3.1.8.1). It is associated with HDL particle and prevents atherosclerosis by cleaving lipid hydroperoxides and other proatherogenic molecules of oxidized low density lipoproteins (LDL). Since the precise structure of HuPON1 is not yet available, the structure-function relationship between HuPON1 and activators/inhibitors is still unknown. Therefore, a theoretical model of HuPON1 was generated using homology modelling and precise molecular interactions of an activator aspirin and an inhibitor cefazolin with PON1 were studied using Autodock software. The ligand binding residues were found to be similar to the predicted active site residues. Both cefazolin and aspirin were found to dock in the vicinity of the predicted active sites of PON1; cefazolin bound at residues N166, S193 and Y71, while aspirin at residues N309, I310 and L311. Binding region in the PON1 by prediction (3D2GO server) and docking studies provide useful insight into mechanism of substrate and inhibitor binding to the enzyme active site.

Cyanidin-3-O-β-glucoside and protocatechuic acid exert insulin-like effects by upregulating PPARγ activity in human omental adipocytes

OBJECTIVE

Insulin resistance (IR) represents an independent risk factor for metabolic, cardiovascular, and neoplastic disorders. Preventing/attenuating IR is a major objective to be reached to preserve population health. Because many insulin-sensitizing drugs have shown unwanted side effects, active harmless compounds are sought after. Dietary anthocyanins have been demonstrated to ameliorate hyperglycemia and insulin sensitivity. This study aimed at investigating whether cyanidin-3-O-β-glucoside (C3G) and its metabolite protocatechuic acid (PCA) might have a role in glucose transport activation in human omental adipocytes and 3T3-L1 cells.

RESEARCH DESIGN AND METHODS

In cells treated with 50 µmol/L C3G and 100 µmol/L PCA, [(3)H]-2-deoxyglucose uptake, GLUT4 translocation by immunoblotting, adiponectin secretion, and peroxisome proliferator-activated receptor-γ (PPARγ) activation by enzyme-linked immunosorbent assay kits were evaluated. Parallel experiments were carried out in murine adipocyte 3T3-L1. To define the role of PPARγ in modulating polyphenol effects, small interfering RNA technique and PPARγ antagonist were used to inhibit transcription factor activity.

RESULTS

C3G and PCA increased adipocyte glucose uptake (P < 0.05) and GLUT4 membrane translocation (P < 0.01). Significant increases (P < 0.05) in nuclear PPARγ activity, as well as in adiponectin and GLUT4 expressions (P < 0.01), were also shown. It is interesting that PPARγ inhibition counteracted the polyphenol-induced adiponectin and GLUT4 upregulations, suggesting a direct involvement of PPARγ in this process.

CONCLUSIONS

Our study provides evidence that C3G and PCA might exert insulin-like activities by PPARγ activation, evidencing a causal relationship between this transcription factor and adiponectin and GLUT4 upregulation. Dietary polyphenols could be included in the preventive/therapeutic armory against pathological conditions associated with IR.

An atherogenic lipid profile with low serum paraoxonase-1 activity during nematode infection in rats

BACKGROUND

Inflammation and oxidative stress are associated with cardiovascular diseases and underlying atherosclerosis. The high density lipoprotein (HDL)-associated paraoxonase-1 (PON1) enzyme is known to be involved in the protection of serum lipids from such oxidation. Nonetheless, the disturbances of lipid profile during nematode-infected model have not yet been studied. Therefore, we aimed to explore the effects of Nippostrongylus brasiliensis infection in male Wistar rats, a model of human gastrointestinal nematode infections, on hepatic PON1 synthesis and the levels of lipid parameters.

MATERIALS AND METHODS

Nippostrongylus brasiliensis-infected rats fed standard and high-fat diets. Serum paraoxonase and arylesterase activities were measured on day 0, 2, 4, 7, and 14 post-infection (PI). Hepatic PONs and pro-inflammatory cytokines mRNA expression levels were evaluated in a standard diet-fed groups, and the disturbances in lipid profile as well as the levels of thiobarbituric acid reactive species (TBARS) and oxidized-LDL (Ox-LDL) were measured in high-fat diet-fed groups.

RESULTS

We found that N. brasiliensis-infected rats fed the standard diet show a significant reduction in serum PON1 activity and down-regulation of hepatic PON1 mRNA expression as well as up-regulation of hepatic IL-1β, IL-β receptor (R), TNF-α, and TNFR1 mRNA expressions in association with hepatic recruitments of Kupffer cells and neutrohils. In the presence of the high-fat diet, N. brasiliensis infection increases serum triglycerides, total cholesterol, LDL/VLDL, TBARS and Ox-LDL as well as decreases serum HDL coinciding with a maximum serum PON1 reduction.

CONCLUSIONS

Nippostrongylus brasiliensis infection can induce atherogenic lipid profile and reduce serum PON1 activity.