Comparison of the oxidant-antioxidant parameters and sialic acid levels in renal transplant patients and peritoneal dialysis patients

Paraoxonase 1 Activity and Renal Replacement Therapy for Chronic Renal Failure: A Meta-Analysis

Chronic renal failure (CRF) is associated with the development of cardiovascular disease (CVD). Paraoxonase 1 (PON1), an antioxidant enzyme, shows cardioprotective properties and has been proposed as a therapeutic marker for CRF. A systematic analysis of the literature assessing the association between PON1 activity and renal replacement therapy (RRT) of CRF is currently lacking. Therefore, we set out to perform a meta-analysis of the available data on PON1 in RRT of CRF. We searched three electronic databases for studies on PON1 activity in CRF patients with RRT such as hemodialysis (HD), peritoneal dialysis (PD), or renal transplantation (RTx), published before June 2023. A random-effects and network meta-analysis were performed. A total of 53 studies were eligibly identified. Compared to CRF patients without RRT, RTx patients had higher paraoxonase activity (standard mean difference (SMD), 1.76, 95% confidence interval (CI), 0.76-2.75), followed by HD (SMD, 0.73; 95% CI, 0.02-1.45) and PD patients. Likewise, RTx patients had higher arylesterase activity (SMD, 1.84, 95% CI, 0.18-3.50), followed by HD and PD patients. Also, paraoxonase activity was increased after HD (SMD, 0.59, 95% CI, 0.16-1.03). In conclusion, the overall data demonstrated that PON1 activity is higher in CRF patients with RRT, particularly RTx, followed by that of HD and PD. Measuring PON1 activity can also be included to the paraclinical toolbox for the management of RRT, in addition to the understanding of CRF-related pathophysiology. Regarding the selection of RRT types and their potential to prevent CVD, more research is required.

Oxidative Stress Markers in Chronic Kidney Disease with Emphasis on Diabetic Nephropathy

Diabetes prevalence is increasing worldwide, especially through the increase of type 2 diabetes. Diabetic nephropathy occurs in up to 40% of diabetic patients and is the leading cause of end-stage renal disease. Various factors affect the development and progression of diabetic nephropathy. Hyperglycaemia increases free radical production, resulting in oxidative stress, which plays an important role in the pathogenesis of diabetic nephropathy. Free radicals have a short half-life and are difficult to measure. In contrast, oxidation products, including lipid peroxidation, protein oxidation, and nucleic acid oxidation, have longer lifetimes and are used to evaluate oxidative stress. In recent years, different oxidative stress biomarkers associated with diabetic nephropathy have been found. This review summarises current evidence of oxidative stress biomarkers in patients with diabetic nephropathy. Although some of them are promising, they cannot replace currently used clinical biomarkers (eGFR, proteinuria) in the development and progression of diabetic nephropathy.

The association of total sialic acid and malondialdehyde levels with metabolic and anthropometric variables in obesity

Serum sialic acid levels are abnormally high in pathological states that exhibit tissue destruction, tissue proliferation or inflammation. We measured total serum sialic acid levels in 139 women and 125 men. Subjects were divided into quartiles according to their body mass index (BMI): Q1 (18-24.9 kg/m(2)), Q2 (25-29.9 kg/m(2)), Q3 (30-39.9 kg/m(2)) and Q4 (> 40 kg/m(2)). The patients in Q1 constituted the control group. Serum sialic acid levels of subjects in Q2, Q3 and Q4 were significantly higher than those in Q1. Higher BMI quartiles also were associated with higher levels of serum glucose, insulin, total cholesterol, LDL-cholesterol, triglycerides, high-sensitivity C-reactive protein, malondialdehyde levels, waist circumference, blood pressure and homeostasis model assessment of insulin resistance in both women and men. Lower BMI quartiles were associated with higher levels of serum HDL-cholesterol levels in both women and men. We found positive associations among serum sialic acid levels, BMI and oxidative stress. Serum sialic acid also is related to some conventional cardiovascular risk factors including elevated lipid profile, increased blood pressure, increased serum glucose and insulin levels, and insulin resistance in obese people.

Effects of calcineurin inhibitors on paraoxonase and arylesterase activity after a kidney transplant

OBJECTIVES

Cardiovascular disease is a common cause of morbidity and mortality in patients with chronic kidney failure, before and after a kidney transplant. Oxidation of lipoproteins that contain apolipoprotein B may contribute to the initiation of atherosclerosis. Paraoxonase may prevent cardiovascular disease. We compared the effects of different calcineurin inhibitors on risk factors for cardiovascular disease in kidney transplant recipients.

MATERIALS AND METHODS

In 16 kidney transplant recipients, treatment included tacrolimus in 8 patients and cyclosporine in 8 patients. Hemoglobin, glucose, renal function, lipid parameters, high-sensitivity C-reactive protein, homocysteine, malondialdehyde, paraoxonase activity, and arylesterase activity were measured before transplant and at 1, 6, and 12 months after the transplant.

RESULTS

The levels of homocysteine and malondialdehyde did not change significantly in patients who received either tacrolimus or cyclosporine. The high-sensitivity C-reactive protein was decreased (tacrolimus group, 1 mo) and increased (cyclosporine group, 6 and 12 mo) after the kidney transplant. Paraoxonase activity was increased (tacrolimus group, 1 mo). Arylesterase activity was increased (tacrolimus group, 1, 6, and 12 mo; cyclosporine group, 1 and 6 mo). The percentage of change in arylesterase activity was higher at 12 months in the tacrolimus than in the cyclosporine group.

CONCLUSIONS

Tacrolimus may be more effective than cyclosporine in improving risk factors for cardiovascular disease after kidney transplant.

Clinical and research markers of oxidative stress in chronic kidney disease

CONTEXT

Kidney-related pathologies have increasing prevalence rates, produce a considerable financial burden, and are characterized by elevated levels of oxidative stress (OS).

OBJECTIVE

This review examines relationships between chronic kidney disease (CKD) and markers of OS and antioxidant status (AS).

METHODS

A systematic review of MEDLINE-indexed clinical trials, randomized controlled trials and comparative studies that examined OS and AS was performed.

RESULTS AND CONCLUSION

Several markers emerged as well-suited indicators of OS and AS in CKD: malondialdehyde, F2-isoprostanes, lipid hydroperoxides, asymmetric dimethylarginine, 8-oxo-7,8-dihydro-2'-deoxyguanosine, protein carbonyls, advanced oxidation protein products and glutathione-related activity.

Stabilization of oxidative stress 1 year after kidney transplantation: effect of calcineurin immunosuppressives

Kidney transplantation (KT) is one of the best treatments for patients with chronic renal disease. It leads to improved kidney function, but the oxidative stress (OS) is only partially eliminated after KT. This study evaluated the effect of KT on outcomes, such as (a) specific kidney functions, (b) metabolic parameters, as well as (c) OS-related markers in 70 patients (46 males, 24 females; mean age = 54 ± 11) before and 1 year after KT. Post KT, the patients were divided into two groups: those receiving only cyclosporine A (N = 36) and those receiving only tacrolimus (N = 34). Improved kidney function (creatinine, urea, and glomerular filtration rate) and biochemical and hematological parameters were found 1 year after KT. OS-related markers (total antioxidant capacity, advanced oxidation protein, and lipid peroxidation products) decreased, but glutathione level increased after KT. Alterations in superoxide dismutase and catalase activities were also found. Glutathione peroxidase levels were unchanged. The level of oxidized low-density lipoprotein was surprisingly, not significantly increased. There was no significant difference between calcineurin inhibitors in any of the measured parameters. Improved renal function after KT is linked to reduction in OS but independent of immunosuppressive therapy.

Paraoxonase 1, atherosclerosis and arterial stiffness in renal patients

Atherosclerosis is an important contributor to increased cardiovascular burden in populations with and without renal disease. Paraoxonases (PON) are a group of enzymes that hydrolyse organophosphates. Recent evidence indicates a protective role for PON in patients with coronary artery disease and atherosclerosis. Although data are limited, the low enzyme activity found in patients with chronic kidney disease and renal transplants has been linked to atherosclerosis and arterial stiffness. In this paper, we review the emerging role of PON1 in the pathophysiology of atherosclerosis and arterial stiffness in patients with chronic kidney disease.