Péter Koncsos

Human paraoxonase-1 activity in childhood obesity and its relation to leptin and adiponectin levels.

Childhood obesity is a predisposing factor for adult cardiovascular diseases. Human serum paraoxonase (PON1) may protect against atherosclerosis by hydrolyzing lipid peroxides in oxidized LDL. Alterations and potential correlations of PON1 activities, leptin and adiponectin levels in childhood obesity were studied. We measured PON1 paraoxonase and arylesterase activities, anthropometric parameters, leptin and adiponectin levels in 59 white, obese (obese group-OB: BMI corrected for age: 95.1 ± 3.5 percentile, age: 11.9 ± 1.6 y) and 51 normal-weight children (control group-C: BMI corrected for age: 64.1 ± 8.4 percentile, age: 12.0 ± 3.9 y). Obese children had significantly lower PON1 paraoxonase (OB: 84.80 (64.33/144.74) U/L versus. C: 99.42 (83.33/152.05) U/L; p < 0.05) and arylesterase activities (OB: 94.40 (82.20/108.70) U/L versus. C: 115.20 (93.70/126.00) U/L; p < 0.01), higher leptin (OB: 37.05 (24.33/53.87) ng/mL versus. C: 4.62 (2.52/17.6) ng/mL; p < 0.0001) and lower adiponectin levels (OB: 7.56 (5.69/12.06) μg/mL versus. C: 11.51 (8.84/14.49) μg/mL; p < 0.001) compared with the normal-weight group. PON1 arylesterase activity showed inverse univariate correlation with leptin (r = −0.29; p < 0.05) and positive correlation with adiponectin levels (r = 0.39; p < 0.01). In multiple regression analysis adiponectin was strongly associated with PON1 arylesterase activity in obese children (β = 0.45, p < 0.02). Our results emphasize the importance of the investigated metabolic alterations which may have further effects on cardiovascular morbidity and mortality in later adulthood. Altered levels of leptin, adiponectin and PON1 activities may be useful markers beside the general risk factors in childhood obesity.

Alteration of PON1 Activity in Adult and Childhood Obesity and Its Relation to Adipokine Levels

Obesity as a pathogenic disorder is a predisposing factor for cardiovascular diseases and shows an increasing incidence in the industrialized countries. Adipokines such as leptin, adiponectin and resistin have a great impact on the development of atherosclerosis in obesity. Elevated levels of leptin have been found to be atherogenic whereas decreased levels of adiponectin have been proved to be anti-atherogenic in recent studies. The exact role of resistin in the process of atherosclerosis has so far remained uncertain and controversial. In our recent work, we studied the alteration in human paraoxonase-1 (PON1) activity and adipokine levels; furthermore, we also aimed at identifying the potential correlation between these parameters in this metabolic disorder. We investigated the above-mentioned parameters both in adults and in children, with regard to the emerging role of childhood obesity and to get a clearer view of these factors during a whole lifetime. Investigating the adult population with a broad range of body mass index (BMI) we found significantly increased leptin and significantly decreased adiponectin and resistin levels and PON1 activity in the obese group compared to the lean controls. Adiponectin and resistin levels showed significantly positive correlation, while leptin and BMI showed significantly negative correlation with PON1 activity. Our findings were similar in childhood obesity: leptin showed significantly negative correlation, while adiponectin showed significantly positive correlation with PON1 activity. We found gender differences in the univariate correlations of leptin and adiponectin levels with PON1 activity in the adult population. In multiple regression analysis, adiponectin proved to be an independent factor of PON1 activity both in childhood and adult obesity, furthermore thiobarbituric acid-reactive substances (TBARS) also proved to be an independent predictor of the enzyme in adults, reflecting the important role of oxidative stress in obesity. Investigating PON 192 Q/R polymorphism by phenotypic distribution (A/B isoenzyme) in obese children, we found a significant correlation of PON1 arylesterase activity with leptin and adiponectin levels, and of body fat percentage with PON1 192 B isoenzyme. According to our studies, these metabolic changes in obesity predispose to the early development of atherosclerosis throughout our whole lifetime. Decreased activity of PON1 and alterations in adipokine levels in childhood obesity could contribute to an early commencement of this process, detected only later in adulthood by increased cardiovascular morbidity and mortality. Changed levels of leptin, adiponectin, resistin and PON1 activity at all ages, just like 192 Q/R polymorphism determined by phenotypic distribution, may be useful markers beside the general risk factors.

Favorable effect of short-term lifestyle intervention on human paraoxonase-1 activity and adipokine levels in childhood obesity.

Objective: The prevalence of obesity is increasing in adult and child populations throughout the world. Childhood obesity has a great impact on adult cardiovascular morbidity and mortality; treatment of this pathological state is important given the significant health consequences. We investigated the effect of short-term lifestyle changes on the alteration of human serum paraoxonase-1 (PON1) activities, leptin, adiponectin, E-selectin, and asymmetric dimethylarginine (ADMA) as atherogenic and antiatherogenic factors in obese children. PON1 protects lipoproteins against oxidation by hydrolyzing lipid peroxides in oxidized low density lipoprotein (LDL) and therefore may protect against atherosclerosis. Methods: A total of 23 white obese and overweight children (age, 11.43 ± 1.78 years; 8 girls, 15 boys) participated in a 2-week-long lifestyle camp based on a diet and exercise program. Overweight and obesity were defined according to the national body mass index (BMI) reference tables for age and sex. Results: After a 2-week-long supervised diet and aerobic exercise program, obese children had significantly lower leptin (55.02 ± 33.42 ng/ml vs 25.37 ± 19.07 ng/ml; p < 0.0001), ADMA (0.68 ± 0.15 μmol/l vs 0.55 ± 0.16 μmol/l; p < 0.01), and E-selectin levels (67.19 ± 30.35 ng/ml vs 46.51 ± 18.40 ng/ml; p < 0.0001), whereas they had significantly higher PON1 paraoxonase activity (110.48 ± 72.92 U/l vs 121.75 ± 93.48 U/l; p < 0.05) besides the antiatherogenic alteration of the lipid profile and significant weight change (70.32 ± 19.51 kg vs 67.01 ± 18.75 kg, p < 0.0001; BMI, 28.95 ± 5.05 kg/m2 vs 27.43 ± 4.82 kg/m2, p < 0.0001). Adiponectin and PON1 arylesterase activity did not change significantly. Conclusions: Our investigation suggests that modifications in dietary habits and physical activity induce antiatherogenic changes in childhood obesity. These findings emphasize the major role of primary prevention and nonpharmaceutical treatment of childhood obesity through lifestyle changes based on diet and increased physical activity.

Effect of Nutritional Status on Human Paraoxonase-1 Activity in Patients with Chronic Kidney Disease

Background/Methods: The association between nutritional status, antioxidant human paraoxonase-1 (PON1) activity and low grade inflammation in hemodialized (HD) patients with chronic kidney disease (CKD) is unclear. The aim of this study was to determine PON1 paraoxonase and lactonase activities, ADMA, adiponectin and leptin concentrations, and to clarify the relationship between paraoxonase activity and a set of cardiovascular risk factors in malnourished, normal weight and obese HD patients; 114 HD patients with end-stage renal failure were enrolled. Results: Leptin levels were significantly higher and PON1 paraoxonase activities were significantly lower in obese patients compared to the other groups. Plasma adiponectin concentration was significantly lower in obese subjects compared to malnourished patients. Paraoxonase activity was negatively correlated with CRP level in HD and malnourished patients. Furthermore, we found significant inverse correlation between paraoxonase activity and BMI in the whole patient group. In multiple regression analysis, PON1 lactonase activity, CRP level and leptin concentration proved to be independent predictors of paraoxonase activity. Conclusion: Despite the previous findings of reverse epidemiology for the mortality rate of HD patients, further studies are needed to clarify the effects of nutritional state on atherosclerosis in obese and malnourished patients with end-stage renal failure.

Neuropeptides induced a pronounced and statin-sensitive dysregulation of mevalonate cycle in human monocytes of patients with hypercholesterolemia.

Angiotensin II (Ang II) and leptin generate statin-inhibitable superoxide anion production that accounts for only part of the entire superoxide anion production. In our recent studies, we aimed at elucidating whether Ang II and leptin, affecting the intensity of the mevalonate cycle, are able to increase endogenous cholesterol synthesis. Furthermore, we compared the superoxide anion and cholesterol production capability of monocytes of healthy control volunteers and monocytes obtained from patients with hypercholesterolemia (HC). We also studied the differences of the produced statin-inhibitable superoxide anion and cholesterol synthesis in control and HC-monocytes, depending on the applied stimulating ligands. In control and HC-monocytes--stimulated by Ang II, leptin, fenyl-Me-Leu-Phe (FMLP), phorbol-12-myristate-13-acetate (PMA) and A23187--we determined the proportion of mevalonate cycle-dependent and -independent superoxide and cholesterol production, using lovastatin (Lov), and 25-hydroxycholesterol (25-HC). According to our results; (1) superoxide anion generation in HC-monocytes was elevated after Ang II, leptin and FMLP-stimulation, whereas PMA and A23187-stimulation had lower stimulating effect in HC than in control cells. (2) Cholesterol synthesis was increased only after stimulation with Ang II and leptin. (3) The Ang II and leptin-induced total superoxide anion generation and cholesterol synthesis were more elevated in HC than in control monocytes. (4) In contrast, the increase in Lov and 25-HC sensitive cholesterol synthesis were higher in resting, but lower in stimulated HC monocytes than in control cells. Summarizing our results, we concluded that Ang II and leptin are involved in enhancement of endogenous cholesterol synthesis through a statin-sensitive pathway.

Low High-Density Lipoprotein Cholesterol Is Not Responsible for Decreased Paraoxonase Activity in Chronic Renal Failure

Background/Aims: Human paraoxonase-1 (PON1) is responsible for the antioxidant effect of high-density lipoprotein (HDL) by inhibiting low-density lipoprotein oxidation. Previous studies discovered dyslipidemia (DL) and decreased PON1 activity in chronic renal failure (CRF). We aimed to determine PON and arylesterase activity, phenotypic distribution of the PON1 enzyme, and lipid profile in low and normal HDL cholesterol (HDL-C) patients with CRF, and renal transplant (TX), compared to primary DL. Methods: 116 CRF (low or normal HDL-C), 52 TX (low or normal HDL-C), and 62 DL patients (low or normal HDL-C) were included. PON and arylesterase activities were measured spectrophotometrically. Phenotype was determined using the dual substrate method. Results: Aryl/HDL-C was significantly higher in low HDL-C patients. Patients with CRF had significantly lower arylesterase activity compared to DL, independent of HDL-C. PON activity and PON/HDL-C did not differ significantly in CRF compared to TX and DL. Phenotypic distribution was similar in patient groups. Low HDL-C CRF patients had significantly lower cholesterol and triglyceride than DL. Conclusion: Decreased arylesterase activity, correlating with PON1 enzyme protein quantity, is not explicable by decreased HDL-C in CRF. Low HDL-C CRF patients’ increased cardiovascular morbidity is not attributable to changes in PON1 activity, or phenotypic distribution.

Paraoxonase-1 arylesterase activity is an independent predictor of myeloperoxidase levels in overweight patients with or without cardiovascular complications.

OBJECTIVES Myeloperoxidase (MPO), matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) were shown to contribute to atherogenesis, while human paraoxonase-1 (PON1) protects against oxidative stress. Although several studies investigated these biomarkers, their associations have not been completely clarified yet. We aimed to investigate these parameters in overweight hyperlipidemic, lipid-lowering therapy-naive patients (n=167) with and without vascular complications. DESIGN AND METHODS MPO, MMP-9 and TIMP-1 levels were measured by ELISA. PON1 activities were detected spectrophotometrically. PON1 phenotype was calculated by using a dual substrate method. RESULTS Patients with vascular complications (VC) had significantly higher MPO and TIMP-1 levels compared to those without (patients with no vascular complications; NVC) (728 (367.25-1177.90) mg/ml vs. 315.9 (176.05-687.40) mg/ml; p<0.001; and 172.7 (157.7-197.7) ng/ml vs. 152.6 (129.3-172.3) ng/ml; p<0.0001; respectively). MPO levels showed a significant negative correlation with PON1 arylesterase activity (whole patient group (W): r=0.42, p<0.0001; VC: r=0.44, p=0.01; NVC: r=0.39, p<0.0001) and positive correlations with MMP-9 (W: r=0.37, p<0.0001; VC: r=0.29, p=0.07; NVC: r=0.42, p<0.0001) and TIMP-1 (W: r=0.42, p<0.0001; VC: r=0.33, p<0.05; NVC: r=0.41, p<0.0001), respectively. PON1 arylesterase activity was found to be an independent predictor of MPO levels in the whole patient group (β=-0.350, p<0.0001) or when studied separately in the subgroups with or without cardiovascular complications (VC: β=-0.57, p<0.05; NVC: β=-0.33, p<0.0001). CONCLUSIONS Our results suggest that parallel investigation of MPO, MMP-9 and TIMP-1 levels and PON1 arylesterase activity may be a more accurate indicator of atherosclerosis, which may allow earlier treatment and therefore, improvement of treatment efficacy.

CSN Society News

Nephrology has a long tradition in the Czech Republic. The first acute dialysis was performed in 1955, a chronic dialysis programme started in the early 60ies, and a transplantation programme in 1966. This was reflected by many important international meetings held in Prague: The 2nd Congress of the International Society of Nephrology (1963), 17th Congress of the European Dialysis and Transplantation Association (1980) and the 15th Congress of the European Society of Artificial Organs (1988). More recently, the 17th and 25th meetings of the International Society of Blood Purification (1999 and 2007), 11th ANCA and Vasculitis Workshop (2003), 7th European Peritoneal Dialysis Meeting (2005), 13th Congress of the European Society of Organ Transplantation (2007) and finally, this year, the 48th Congress of ERA-EDTA.