Increased peroxiredoxin 4 levels in patients with prediabetes compared to normal glucose tolerance subjects

Correlation of glycemic control with salivary oxidative markers in subjects with prediabetes and diabetes: A cross-sectional study

Background and aims

Rising levels of oxidative stress play an important role in the pathogenesis of type 2 diabetes mellitus. This study aimed to some assess salivary antioxidants in patients with type 2 diabetes, prediabetes, and healthy control. We also assessed the potential clinical relevance of salivary antioxidants with glycemic control.

Methods

This cross-sectional study included 30 prediabetes, 31 type 2 diabetes, and 39 sex-matched normoglycemic individuals. To assess the salivary oxidative status, we measured the levels of malondialdehyde (MDA), superoxide dismutase (SOD), the total antioxidant capacity (TAC), and uric acid (UA) by spectrophotometry.

Results

Salivary MDA levels were significantly higher in individuals with diabetes compared to prediabetes, and control groups (p = 0.001). MDA and SOD were significantly correlated with fasting blood sugar (FBS) and HbA1C (p < 0.001, r = 0.43, p < 0.001, r = 0.34, and p = 0.003, r = 0.29 p = 0.01, r = 0.23 respectively). Salivary TAC was also significantly correlated with FBS (p = 0.02, r = 0.23). Furthermore, salivary MDA was an independent determinant of type 2 diabetic patients compared to healthy subjects (p = 0.04). According to the cutoff point in the ROC curve, the MDA index was below 2.8 in 82.1% of the controls (specificity), and it was above 2.8 in 64.2% of the Individuals with diabetes (sensitivity).

Conclusion

The simultaneous assessment of salivary oxidative and antioxidant factors, revealed weak but a significant positive association between MDA and glycemic status in diabetes. However, further investigations are required to confirm our results.

Essential Roles of Peroxiredoxin IV in Inflammation and Cancer

Peroxiredoxin IV (Prx4) is a 2-Cysteine peroxidase with ubiquitous expression in human tissues. Prx4 scavenges hydrogen peroxide and participates in oxidative protein folding in the endoplasmic reticulum. In addition, Prx4 is secreted outside the cell. Prx4 is upregulated in several cancers and is a potential therapeutic target. We have summarized historical and recent advances in the structure, function and biological roles of Prx4, focusing on inflammatory diseases and cancer. Oxidative stress is known to activate pro-inflammatory pathways. Chronic inflammation is a risk factor for cancer development. Hence, redox enzymes such as Prx4 are important players in the crosstalk between inflammation and cancer. Understanding molecular mechanisms of regulation of Prx4 expression and associated signaling pathways in normal physiological and disease conditions should reveal new therapeutic strategies. Thus, although Prx4 is a promising therapeutic target for inflammatory diseases and cancer, further research needs to be conducted to bridge the gap to clinical application.

Association of Prx4, Total Oxidant Status, and Inflammatory Factors with Insulin Resistance in Polycystic Ovary Syndrome

INTRODUCTION

Chronic inflammation and oxidative stress conditions have been reported in women with polycystic ovary syndrome (PCOS). Peroxiredoxin 4 (Prx4) is a related antioxidant in insulin synthesis. We hypothesized that insulin resistance in these women is associated with total oxidant status (TOS) and inflammatory factors.

MATERIALS AND METHODS

Two hundred three people including 104 PCOS patients and 99 healthy women, who were matched for age and body mass index (BMI), entered the study. Waist circumference of the participants was measured; serum glucose, lipid profile, insulin, Prx4, TOS, hs-CRP, and TNF-α were also evaluated.

RESULTS

The Prx4 level was significantly lower in PCOS than in the control group. In addition, marked increase was observed in the concentration of TOS, hs-CRP, and TNF-α in PCOS, compared to the healthy women. There was a positive correlation of TOS with hs-CRP, TNF-α, and HOMA-IR. The risk of PCOS for subjects with high hs-CRP was 60 times greater than those who had low serum hs-CRP concentration; after performing multiple logistic regression analyses with the backward method, TNF-α was considered as an effective biomarker to predict PCOS β = 49.087 (all p < 0.05).

CONCLUSION

This study identified increased oxidative stress and inflammation in PCOS; this may be due to decrease in the antioxidants, such as Prx4.

Endothelial dysfunction and intima media thickness are selectively related to the different carbohydrate disturbances across the glucose continuum

Aim: The aim of the present study was to investigate the prevalence of macrovascular complications across different carbohydrate disturbances. Patients and methods: In the study, we included 167 patients, divided them into three age and BMI matched groups - group 1 with obesity without carbohydrate disturbances (n = 66), group 2 with prediabetes (n = 68) and group 3 with newly diagnosed type 2 diabetes (n = 33). Endothelial function was evaluated using EndoPAT, intima media thickness (IMT) was measured on the common carotid artery and ankle-brachial index (ABI) was calculated. Results: The patients with T2D had significantly higher mean IMT than the other two groups. The best predictors of increased IMT were fasting blood glucose followed by age and SBP. ROC-analysis showed that blood glucose on 60 min of OGTT had a very good predictive value for endothelial dysfunction. Conclusions: Patients with newly diagnosed diabetes have increased IMT and a tendency towards higher ABI compared to normoglycemic and prediabetic subjects.

Plasma level of peroxiredoxin 3 in patients with polycystic ovarian syndrome

BACKGROUND

As a member of peroxiredoxin (PRX) family, PRX3 is predominantly located in mitochondria and plays an important role of free radical scavenging. Since a body of evidence demonstrated the involvement of PRX3 in insulin secretion, insulin sensitivity, and glucose metabolism, the present study was conducted to investigate the role of PRX3 in the pathogenesis of polycystic ovarian syndrome (PCOS) featured in insulin resistance.

METHODS

Enzyme-linked immunosorbent assay was performed to detect plasma PRX3 in PCOS patients and control subjects. Levels of reactive oxygen species (ROS) and oxidized PRXs were detected in mouse islet cells treated with gradient glucose.

RESULTS

We did not find significant difference of fasting plasma PRX3 between PCOS patients and controls. No association was noticed between fasting plasma PRX3 and fasting plasma glucose or insulin. After oral glucose tolerance test (OGTT), PCOS patients showed higher levels of both glucose and insulin as compared to controls. The plasma level of PRX3 was significantly increased at 2 h and began to fall back at 3 h of OGTT. There was a one-hour time lag of peak values between plasma PRX3 and insulin, and the plasma PRX3 at 2 h was positively correlated with the insulin level at 1 h of OGTT of PCOS patients. In addition, the level of ROS was significantly elevated at 1 h and oxidized PRX3 was increased dramatically at 2 h of 16.7mM glucose stimulation in mouse islet cells.

CONCLUSION

It seems that PRX3 does not show its antioxidant function under baseline conditions. Instead, PRX3 responds to oxidative stress induced by rapid increase of insulin and glucose in patients with PCOS.