Hyperhomocysteinemia, paraoxonase concentration and cardiovascular complications in Tunisian patients with nondiabetic renal disease

Paraoxonase 1 and Chronic Kidney Disease: A Meta-Analysis

Oxidative stress is known to be associated with the pathophysiology of chronic kidney disease (CKD). Paraoxonase 1 (PON1) is an antioxidant enzyme that has been proposed as a biomarker for CKD. While several studies have reported an association between serum PON1 activity and CKD, consensus based on systematically analyzed data remains necessary. We set out to conduct a meta-analysis of literature on PON1 in CKD. Electronic databases, such as MEDLINE, Embase and CENTRAL, were searched for available studies on PON1 activity in patients with CKD (without dialysis) as published before December 2022. A random-effects meta-analysis was performed. In total, 24 studies (22 studies on paraoxonase and 11 on arylesterase activity) were eligibly identified. Patients with CKD showed a lower activity of paraoxonase (standard mean difference [SMD], -1.72; 95% confidence interval [CI], -2.15 to -1.29) and arylesterase (SMD, -2.60; 95%CI, -3.96 to -1.24) than healthy controls. In the subgroup analyses, paraoxonase activity was lower in chronic kidney failure (CKF), an advanced stage of CKD, than in non-CKF. In summary, PON1 activity is low in patients with CKD, suggesting that the antioxidant defense by PON1 is impaired in CKD. The decrease in enzyme activity is pronounced in advanced CKD showing some variability depending on the substrate employed to measure PON1 activity. Further studies are warranted.

PON1 status and homocysteine levels as potential biomarkers for cardiovascular disease

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of death. The mainly risks factors for CVD are diabetes, hypertension and high levels of homocysteine (Hcys), among others. Paraoxonase 1 (PON1) has been proposed as an antiatherogenic target for its ability to hydrolyzing oxi-Low-Density-Lipoproteins (LDL) and Hcys-thiolactone. Thus, the aim of the present study was to evaluate the association of Hcys levels, and the activities and concentration of PON1, as well as vitamin B from the diet with a risk for CVD.

METHODS

A case-control study was carry out in patients with cardiovascular diseases (CVD), Arterial hypertension, but not CVD (AH), and in healthy controls (control group) from the Mexican Institute of Social Security. Lipid profile, intake of vitamin B, Hcys, serum amyloid A (SAA), PON1 concentration, and PON1 activities (Arylesterase activity (ARE), Lactonase activity (LAC), and CMPA activity (CMPA)) were evaluated.

RESULTS

The CVD group had the highest concentration of Hcys and SAA than in the AH and control groups (p < 0.01). ARE, LAC, and CMPA activities and PON1 concentration were lowest in the CVD group. A positive-independent association between Hcys levels and CVD was found (OR = 2.09; 95% CI: 1.69-2.56) and this increase when it was adjusted by age, BMI, ApoA1, vitamin B intake, SAA, and PON1 (OR = 14.41; 95% CI: 1.75-118.71). LAC and CMPA, as well as PON1 concentration, were inversely associated with CVD.

CONCLUSION

LAC activity, PON1 concentration, and Hcys levels might be good biomarkers for CVD and their association could be modified by the intake of vitamin B.

Metabolic interactions between hyperhomocysteinemia and endothelin-1 among Tunisian patients with acute coronary diseases

BACKGROUND

Acute coronary syndromes (ACS) are complex and polygenic diseases which are a real problem of public health. These syndromes require multidisciplinary studies to understand the pathogenesis mechanisms and metabolic interactions between different risk factors.This study aimed to explore the variation of two coronary risk parameters not mentioned by Framingham cohorts, hyperhomocysteinemia and endothelin-1 (ET-1) in Tunisian coronary and the study of the variation of these parameters based on various cardiac risk factors and metabolic relationship between them.To 157 coronary and 142 healthy subjects, the concentration of homocysteine was quantified by fluorescence polarization immunoassay; the concentration of ET-1 was measured by an analytical technique, the High Performance Liquid Chromatography (HPLC) coupled with mass spectrometry.

RESULTS

Our study showed that homocysteine and ET-1 were significantly higher in patients compared to healthy subjects (24.40 ± 12.5 μmol/L vs 7.44 ± 2.5 μmol/L p <0.00001) for homocysteine and (15.2 ± 5.3 nmol/L vs 7.1 ± 2.7 nmol/L, p <0.00001) for ET-1. On the other hand, homocysteine varies according to tobacco and diabetes while ET-1 depends on the sex, hypertension, smoking, obesity and dyslipidemia and a statistically negative correlation was shown between homocysteine and ET-1 in coronary patients (r = -0.66 p <0.00001).

CONCLUSION

The study of the variation of these two parameters in coronary patients and metabolic exploration of the relationship between homocysteine and ET-1 according to various risk factors and the interactions between themselves facilitates the decision of therapeutic treatment.

Diagnostic value of the combined measurement of serum hcy, serum cys C, and urinary microalbumin in type 2 diabetes mellitus with early complicating diabetic nephropathy

Diabetic nephropathy (DN) is a major cause of end-stage kidney disease, and therefore early diagnosis and intervention may help reverse renal damage. One hundred and sixty-eight patients with T2DM and 56 healthy volunteers (control group) were enrolled at Shandong University Qilu Hospital between April 2010 and October 2012. All subjects underwent blood sampling for sera homocysteine (Hcy) and cystatin C (Cys C) assays and a urine microalbumin test. The patients were divided into three groups according to the urine microalbumin excretion rate (UMAER): the simple DM group (SDM group, n = 51), the early-stage DN group (EDN group, n = 60), and the clinical DN and renal failure group (CDN group, n = 57). Correlation analysis was performed to examine the association between sera Hcy and Cys C levels with UMAER. Our findings showed that sera Hcy level, Cys C level, and UMAER increased significantly in the SDM group (P < 0.05, P < 0.01), the EDN group (P < 0.01), and the CDN group (P < 0.01) as compared with the control group. These three biochemical markers also increased significantly with DN progression (P < 0.01). Correlation analysis showed that sera Hcy and Cys C levels were positively correlated with UMAER (r = 0.702, P < 0.01; r = 0.873, P < 0.01). In conclusion, our results showed that sera Hcy and Cys C levels increased consistently with the development and progression of DN as indicated by UMAER. Sera Hcy and Cys C are sensitive biomarkers for the detection of early-stage DN and monitoring its progression.

Paraoxonase 1 in chronic kidney failure

In this review we summarize the findings from the literature and our own laboratory on the decreased PON1 activity in renal failure, the mechanisms proposed and the effect of interventions. In addition to profound alterations in lipoproteins, reduced serum PON1 activity has been clearly established in the past decade and could contribute to accelerated development of atherosclerosis in ESRD and in HD. PON1 lactonase activity is lower in ESRD patients. Hemodialysis partially restores PON1 lactonase and the other activities. PON1 activity recovery after dialysis suggests that uremic toxins may play a mechanistic role in PON1 inactivation. Lower PON1 activity in CRF patients is associated with low thiol concentration, high CRP, and is beneficially enhanced with vitamin C and flavonoids. Changes in HDL subclasses, namely lower HDL₃ in these patients may also play a role in PON1 lower activity. Future research should focus on: (1) mechanistic studies on causes for low PON1 activity and mass; (2) prospective studies focusing on whether there is an added predictive value in measuring PON1 activity (and PON1 activity in HDL₃) in this patient population; (3) intervention studies attempting to increase PON1 activity.

Relationship between paraoxonase and homocysteine: crossroads of oxidative diseases

Homocysteine (Hcy) is an accepted independent risk factor for several major pathologies including cardiovascular disease, birth defects, osteoporosis, Alzheimer's disease, and renal failure. Interestingly, many of the pathologies associated with homocysteine are also linked to oxidative stress. The enzyme paraoxonase (PON1) - so named because of its ability to hydrolyse the toxic metabolite of parathion, paraoxon - was also shown early after its identification to manifest arylesterase activity. Although the preferred endogenous substrate of PON1 remains unknown, lactones comprise one possible candidate class. Homocysteine-thiolactone can be disposed of by enzymatic hydrolysis by the serum Hcy-thiolactonase/paraoxonase carried on high-density lipoprotein (HDL). In this review, Hcy and the PON1 enzyme family were scrutinized from different points of view in the literature and the recent articles on these subjects were examined to determine whether these two molecular groups are related to each other like a coin with two different sides, so close and yet so different and so opposite.