Ildikó Seres

Study of factors influencing the decreased HDL associated PON1 activity with aging.

Paraoxonase (PON1) is principally complexed to HDL and is responsible, at least in part, for its antioxidant properties. PON1 activity decreases in several pathologies associated with atherosclerosis. The aim of this study was to investigate the PON1 activity and factors influencing its activity as a function of age. One hundred and twenty nine healthy subjects aged between 22 and 89 years were recruited for the study. We found that serum PON1 activity significantly decreased with age (r=-0.38, p<0.0001) while its arylesterase activity as well as its concentration in the serum did not change significantly. HDL concentrations remained unchanged with age, however, Apo A1 concentration showed a slight negative but significant correlation with age (r=-0.19, p<0.027). Moreover, the total cholesterol concentration was positively and significantly correlated with age (r=0.40, p<0.001). Thus, our results suggest that the decrease in PON1 activity cannot be explained by the decrease in Apo A1 concentrations with age. HDL from elderly subjects was more susceptible to oxidation than HDL from young subjects measured by higher lipid peroxidation rate. Thus, the decrease in PON1 activity may contribute to this increased susceptibility of HDL to oxidation with aging. Altogether our results suggest that the decrease in PON1 activity may be related to the development of oxidative stress conditions with aging and the increased HDL susceptibility to oxidation in elderly subjects.

Modulation of human lymphocyte proliferative response with aging

Previously, we have demonstrated age-associated alterations in transmembrane signaling. One of the most reproducible alterations found in the immune response with aging is the decrease of lymphocyte proliferation on stimulation with various different mitogens. Here, we confirm that proliferative responses to stimulation with phytohaemagglutin (PHA), recombinant human IL-2, or anti-CD3 monoclonal antibody are all greater in the young (20-25 years) than old (60-87 years) population. We attempted to modulate the proliferative response using various agents acting at different levels of transmembrane signaling (pertussis toxin, cholera toxin, isoproterenol, PMA, Ca ionophore A23187), as well as at the level of the lymphocyte plasma membrane (methyl-beta-cyclodextrin, MBCD), or by using antioxidant vitamins (Vitamin E or C). None of these agents was able to restore effectively the proliferative response of lymphocytes from the aged to the level of young subjects. Even the combination of A23187 and PMA acting directly on calcium metabolism and protein kinase C activity was insufficient to restore the decreased mitogenic capacity of T cells from elderly subjects. Cyclodextrin, which decreases the cholesterol content of the membrane, increased the proliferative response of lymphocytes of elderly subjects, but not to the level of the young. Vitamin E had a very strong inhibitory effect on lymphocyte stimulation in both the age groups, except in combination with MBCD in T cells of the elderly, while Vitamin C had no significant modulatory effect. MAPK ERK and p38 activation was found to be decreased with aging in T cells after anti-CD3 mAb stimulation. Vitamin E but not Vitamin C strongly inhibited MAPK ERK or p38 activation. The direct activation of certain molecules or the modulation of the cholesterol content of the membrane seems to be effective immunomodulatory interventions with aging.

The Serum Paraoxonase Activity in Patients with Chronic Renal Failure and Hyperlipidemia

Human serum paraoxonase is physically associated with an apolipoprotein (Apo-A1) and clusterin-containing high-density lipoprotein (HDL) and prevents low-density lipoprotein from lipid peroxidation. The aim of our study was to determine whether paraoxonase activity or phenotype is altered in patients with chronic renal failure and in hyperlipidemic subjects without renal insufficiency and to compare the values with those of healthy controls. We investigated the serum paraoxonase activity and polymorphism in 119 hemodialyzed uremic patients, 107 patients with primary hyperlipoproteinemia, and in 110 healthy control subjects. The serum paraoxonase activity was significantly decreased both in hyperlipidemic (p < 0.01) and uremic patients (p < 0.001) as compared with controls. On comparison, the serum paraoxonase activity was significantly lower (p < 0.001) in uremic than in hyperlipoproteinemic patients. The HDL and Apo-A1 levels were as follows: uremic < hyperlipidemic < control. To assess whether the observed reduction in paraoxonase activity was due to HDL and Apo-A1 level decreases, we standardized the enzyme activity for HDL and Apo-A1 concentrations. We found that the standardized paraoxonase activity (paraoxonase/HDL ratio) was also lower in the uremic patients (103.3 ± 69.5) as compared with hyperlipidemic patients (137.64 ± 81.0) and controls (194.45 ± 94.45). The standardized values for Apo-A1 showed a similar tendency: paraoxonase/Apo-A1 ratio in uremic patients 89.64 ± 47.8, in hyperlipidemic patients 128.12 ± 69.83, and in controls 161.40 ± 47.35. The phenotypic distribution of paraoxonase (AA, AB, BB) did not change significantly in the patient groups. These results suggest that HDL concentration and phenotypic distribution of paraoxonase may not be the only determining factors, but that other as yet undetermined factors could be involved in the enzyme activity changes.

Serum paraoxonase activity changes in patients with Alzheimer's disease and vascular dementia

Abstract The prevalence of Alzheimers disease (AD) and vascular dementia (VAD) increases with aging of the population. The role of lipoproteins in the pathogenesis of AD is unclear: apoE2 offers protection and apoE3 is neutral, while apoE4 promotes the development of the disease.Recently, several studies have confirmed the role of oxidative stress in the pathogenesis of AD and VAD. HDL-associated paraoxonase is one of the antioxidative enzymes that may reduce LDL oxidation. In our study, we investigated the lipid parameters of the sera and the serum paraoxonase activity in patients with AD and VAD.Lipid parameters were determined by an autoanalyzer in 30 AD patients, 40 VAD patients and 40 healthy, age-matched control (C) subjects. Paraoxonase activity was measured spectrophotometrically using paraoxon as the substrate. The phenotypic distribution of paraoxonase was determined by the dual substrate method, using paraoxon and phenylacetate as substrates.In our results, we found that most of the patients with AD had the apoE4 isoform, consistent with other studies. In the VAD and AD patients we found significantly higher total-cholesterol compared to the control group (C: 4.71 ± 0.89, VAD: 6.3 ± 0.8, AD: 6.52 ± 0.7 mmol/l; p < 0.01) and LDL-cholesterol levels (C: 2.6 ± 0.6, VAD: 3.96 ± 0.8, AD: 3.84 ± 0.6 mmol/l; p < 0.001). The HDL-associated antioxidant, paraoxonase activity did not differ significantly in the patient groups, but compared to the healthy control subjects, paraoxonase activity was significantly lower in both of the patient groups (C: 188 ± 55 U/l; AD: 131 ± 37, VAD: 151 ± 50 l; p < 0.05).Our results suggest that the defect in HDL-associated antioxidant capacity plays a role in the pathogenesis of Alzheimers disease and vascular dementia.

Serum paraoxonase activity changes in uremic and kidney-transplanted patients

Serum paraoxonase (PON) is a high-density lipoprotein (HDL)-associated hydrolase, which inhibits low-density lipoprotein oxidation. Uremic and kidney-transplanted patients have an increased risk of atherosclerosis, to which an increased lipoprotein oxidation may contribute. The aim of our study was to determine whether the PON activity or phenotype is altered in uremic and kidney-transplanted patients, and to compare the values with those of healthy controls. 117 uremic patients on long-term hemodialysis treatment, 115 renal-transplanted patients, and 110 healthy controls were involved in the study. The PON activity was significantly reduced in the uremic patients compared to controls (PON 101.36±30.12 vs. control 188.05±58.96 U/ml; p < 0.001), while in kidney-transplanted patients the values were almost identical to those of controls (PON 161.5±35.39 U/ml). The different immunosuppressive drug combinations did not influence PON activity. To assess whether the altered PON activity was due to a decrease HDL level, we standardized the enzyme activity for the HDL concentration (PON/HDL ratio). We found that the standardized enzyme activity was lower in the uremic (102.7±54.8) and kidney-transplanted patients (144.5±32.7) when compared to controls (194.5±94.5; p < 0.001). The phenotypic distribution of PON in uremic, renal transplant and control patients are as follows: AA 66.67, 56.48 and 66.67%; AB 31.62, 33.3 and 26.67%; BB 1.71, 10.19 and 6.67%. We conclude that the decreased PON/HDL and PON/apoA-1 ratios may lead to a reduction in the antioxidant capacity of HDL, which might contribute to the accelerated development of atherosclerosis in uremic and kidney-transplanted patients.

Assessment of Subclinical Vascular Disease Associated with Ankylosing Spondylitis

Objective. Studies indicate that ankylosing spondylitis (AS), as well as rheumatoid arthritis, may be associated with accelerated atherosclerosis and vascular disease. We assessed endothelial dysfunction, carotid atherosclerosis, and aortic stiffness in AS in context with clinical and laboratory measurements. Methods. Forty-three patients with AS and 40 matched healthy controls were studied. We assessed common carotid intima-media thickness (ccIMT), flow-mediated vasodilation (FMD), and pulse-wave velocity (PWV) in association with age, disease duration, smoking habits, body mass index, patient’s assessment of pain and disease activity, Bath AS Disease Activity Index, Bath AS Functional Index (BASFI), metric measurements, erythrocyte sedimentation rate, C-reactive protein, and HLA-B27 status. Results. We found impaired FMD (6.85 ± 2.98% vs 8.30 ± 3.96%; p = 0.005), increased ccIMT (0.65 ± 0.15 vs 0.54 ± 0.15 mm; p = 0.01), and higher PWV (8.64 ± 2.44 vs 8.00 ± 1.46 m/s; p = 0.03) in patients with AS compared to controls, respectively. We also found that ccIMT negatively correlated with FMD (r = −0.563; p = 0.0001) and positively correlated with PWV (r = 0.374; p = 0.018). Both ccIMT and PWV correlated with disease duration (r = 0.559; p = 0.013 and r = 0.520; p = 0.022, respectively), BASFI (r = 0.691; p = 0.003 and r = 0.654; p = 0.006), decreased lumbar spine mobility (r = −0.656; p = 0.006 and r = −0.604; p = 0.013), chest expansion (r = −0.502; p = 0.047 and r = −0.613; p = 0.012), and increased wall-occiput distance (r = 0.509; p = 0.044 and r = 0.614; p = 0.011). Conclusion. In this well characterized AS population, impaired FMD and increased ccIMT and PWV indicate abnormal endothelial function and increased atherosclerosis and aortic stiffness, respectively. The value of noninvasive diagnostic tools needs to be further characterized.

Rheumatoid arthritis and metabolic syndrome

Rheumatoid arthritis (RA), especially active disease, is associated with considerable changes in body composition, lipids, adipokines and insulin sensitivity. Metabolic changes, such as increased total cholesterol, LDL cholesterol and triglyceride levels, occur even in preclinical RA. Active RA is associated with decreased lipid levels, BMI, fat and muscle mass, as well as altered lipid profiles. Some of these changes are also seen in metabolic syndrome, and could increase cardiovascular mortality. Importantly, the systemic inflammation underlying RA is an independent risk factor for cardiovascular disease. This Perspectives article summarizes data on the associations of various components of metabolic syndrome with RA, and discusses the effects of biologic therapy on these factors. The authors propose that components of metabolic syndrome should be monitored in patients with RA throughout the disease course, and argue that optimal disease control using biologic agents might attenuate several adverse effects of metabolic syndrome in these patients.

Vitamin D insufficiency in a large MCTD population

OBJECTIVES The aim of the present study was to evaluate the vitamin D status in patients with mixed connective tissue disease (MCTD) and to determine which clinical symptoms, laboratory parameters and endothelial cell markers are associated with low vitamin D levels. METHODS 125 female MCTD patients and 48 age- and sex-matched healthy controls were enrolled in the study. The clinical symptoms, autoantibodies (anti-U1-RNP, anti-cardiolipin - anti-CL and anti-endothelial cell antibody - AECA), serum cytokines (IFN-γ, IL-6, IL-12, IL-23, IL-17 and IL-10), soluble endothelial cell markers (endothelin, thrombomodulin - TM, and von Willebrand factor antigen - vWFAg) and serum lipids (total cholesterol, triglyceride, LDL-C, HDL-C, apolipoprotein A1, and apolipoprotein B) were investigated for an association with vitamin D levels by univariate and multivariate statistical analyses. RESULTS The mean vitamin D levels were significantly lower in MCTD patients, as compared with the control group (26.16±13.50ng/ml vs. 34.92±9.64ng/ml; p<0.001). In laboratory parameters, vitamin D levels were inversely associated with serum IL-6 (p<0.001), IL-23 (p=0.011), IL-10 (p=0.033) cytokine levels, TM (p=0.001) and endothelin (p=0.033) levels. Low vitamin D levels were also significantly associated with carotid artery intima media thickness (p<0.001), fibrinogen (p=0.010), total cholesterol (p=0.042) and ApoA1 (p=0.004) levels. Among the clinical symptoms, the cardiovascular involvement showed an inverse correlation with vitamin D status in MCTD (p<0.001). CONCLUSIONS The prevalence of vitamin D insufficiency is high in patients with MCTD. We assume that vitamin D insufficiency along with inflammatory parameters and lipid abnormalities may provoke cardiovascular events.

Reduced Paraoxonase1 Activity Is a Risk for Atherosclerosis in Patients with Systemic Lupus Erythematosus

Abstract:  Excessive lipid peroxidation is a major factor of accelerated atherosclerosis, observed in patients with systemic lupus erythematosus (SLE). We aimed at the present study to determine the paraoxonase1 (PON1) and arylesterase activities, and lipid‐profile in 37 SLE patients and 30 age‐/sex‐matched controls. Association was analyzed between PON1 activity and SLEDAI, CRP, anti‐oxLDL, and antiphospholipid antibody (aPL) levels, steroid dose, and atherothrombotic events. The age of patients was 40.8 ± 13.9 year, follow‐up time 6.7 ± 6.2 year, SLEDAI 2 (0–15). PON1 and arylesterase activities were measured spectrophotometrically using paraoxon and phenyl acetate as substrates, respectively. Phenotypic distribution of PON1 was determined by dual substrate method. We measured anti‐oxLDL and aPL levels by ELISA, the CRP by automated immunoassay. PON1 activity (121.9 ± 65.9 U/mL) was reduced significantly (P < 0.001) in SLE as compared to control (188.1 ± 78.9 U/mL), but arylesterase activity was not different. A negative correlation was found between PON1 activity and age. PON1 activity did not correlate with other measured parameters. Reduced PON1 activity associated with clinical atherothrombotic complications (P < 0.01). High activity BB phenotype was not present in SLE. Lipid parameters (TC, LDL‐C, HDL‐C, ApoAI, and ApoB) were within normal range in both groups. Results indicated reduced PON1 activity in lupus patients despite long disease duration and low inflammatory activity, and it was evidenced as a risk for atherosclerotic complications. As the arylesterase activity was normal, further examinations are required to find other mechanisms, such as anti‐PON1 antibodies, genetic polymorphisms, and difference in distribution of HDL‐subfractions or enzyme abnormalities in HDL remodeling.

NEUTROPHILS OBTAINED FROM OBLITERATIVE ATHEROSCLEROTIC PATIENTS EXHIBIT ENHANCED RESTING RESPIRATORY BURST AND INCREASED DEGRANULATION IN RESPONSE TO VARIOUS STIMULI

Tissue destruction in atherosclerosis is partly due to uncontrolled protease and oxygen radical release. In this study we investigated the release of elastase and myeloperoxidase, as well as the production of reactive oxygen species by polymorphonuclear leukocytes (PMNLs) obtained from patients with obliterative atherosclerotic of the lower legs. In addition we measured the plasma concentration of xanthine oxidase. PMNLs of atherosclerotic patients have a greater ability to increase elastase and myeloperoxidase release after their stimulation with formyl-methionin-leucyl-phenylalanin (fMLP) and calcium ionophore, A23187, independently of their age, than PMNLs of healthy middle-aged subjects. Similarly to healthy elderly subjects there was an increased superoxide anion (O2-) production under basal condition in both atherosclerotic patient age-groups. The activation of PMNLs with fMLP and A23187 enhanced O2- formation both in healthy subjects and in patients with atherosclerotic disease of the lower legs, however the increase was significantly less in the latter group. No biochemical parameters showed significant correlation with patients risk factors, however myeloperoxidase production was significantly higher in less severe stage of the disease (P < 0.05). We found that patients with atherosclerotic disease of the lower legs have higher plasma xanthine oxidase level than control subjects. This study indicates an other piece of evidence suggesting the activation and involvement of neutrophils in the pathogenesis of atherosclerosis of the lower legs. The similar tendencies in the reactivity of neutrophils during aging and in atherosclerosis suggest that atherosclerosis may be an early aging process.