Plasma levels of lipoprotein-associated phospholipase A(2) are increased in patients with ß-thalassemia.

Lipoprotein-associated phospholipase A(2) (Lp-PLA(2)) is an independent cardiovascular risk factor. We investigated the plasma levels of Lp-PLA(2) activity and mass as a function of plasma lipid levels, LDL subclass profile, and oxidative stress in patients with ß-thalassemia. Thirty-five patients with ß-thalassemia major (ß-TM) and 25 patients with ß-thalassemia intermedia (ß-TI) participated in the study. Lp-PLA(2) activity and mass were measured in total plasma, in apolipoprotein (apo)B-depleted plasma (HDL-Lp-PLA(2)), and in LDL subclasses. Lp-PLA(2) activity produced and secreted from peripheral blood monocytes in culture was also determined. Patients with ß-thalassemia are characterized by a predominance of small-dense LDL particles, increased oxidative stress, and very high plasma levels of Lp-PLA(2) mass and activity, despite low LDL-cholesterol levels. A significant positive correlation between plasma Lp-PLA(2) activity or mass and 8-isoprostane (8-epiPGF2a) and ferritin levels as well as intima-media thickness (IMT) values was observed. An increase in secreted and cell-associated Lp-PLA(2) activity from monocytes in culture was observed in both patient groups. The HDL-Lp-PLA(2) activity and mass as well as the ratio of HDL-Lp-PLA(2)/plasma Lp-PLA(2) were significantly higher in both patient groups compared with the control group. In conclusion, patients with ß-thalassemia exhibit high plasma Lp-PLA(2) levels, attributed to increased enzyme secretion from monocytes/macrophages and to the predominance of sdLDL particles in plasma. Plasma Lp-PLA(2) is correlated with carotid IMT, suggesting that this enzyme may be implicated in premature carotid atherosclerosis observed in ß-thalassemia.

Patients with early rheumatoid arthritis exhibit elevated autoantibody titers against mildly oxidized low-density lipoprotein and exhibit decreased activity of the lipoprotein-associated phospholipase A2.

Rheumatoid arthritis is a chronic inflammatory disease, associated with an excess of cardiovascular morbidity and mortality due to accelerated atherosclerosis. Oxidized low-density lipoprotein (oxLDL), the antibodies against oxLDL and the lipoprotein-associated phospholipase A2 (Lp-PLA2) may play important roles in inflammation and atherosclerosis. We investigated the plasma levels of oxLDL and Lp-PLA2 activity as well as the autoantibody titers against mildly oxLDL in patients with early rheumatoid arthritis (ERA). The long-term effects of immunointervention on these parameters in patients with active disease were also determined. Fifty-eight ERA patients who met the American College of Rheumatology criteria were included in the study. Patients were treated with methotrexate and prednisone. Sixty-three apparently healthy volunteers also participated in the study and served as controls. Three different types of mildly oxLDL were prepared at the end of the lag, propagation and decomposition phases of oxidation. The serum autoantibody titers of the IgG type against all types of oxLDL were determined by an ELISA method. The plasma levels of oxLDL and the Lp-PLA2 activity were determined by an ELISA method and by the trichloroacetic acid precipitation procedure, respectively. At baseline, ERA patients exhibited elevated autoantibody titers against all types of mildly oxLDL as well as low activity of the total plasma Lp-PLA2 and the Lp-PLA2 associated with the high-density lipoprotein, compared with controls. Multivariate regression analysis showed that the elevated autoantibody titers towards oxLDL at the end of the decomposition phase of oxidation and the low plasma Lp-PLA2 activity are independently associated with ERA. After immunointervention autoantibody titers against all types of oxLDL were decreased in parallel to the increase in high-density lipoprotein-cholesterol and high-density lipoprotein-Lp-PLA2 activity. We conclude that elevated autoantibody titers against oxLDL at the end of the decomposition phase of oxidation and low plasma Lp-PLA2 activity are feature characteristics of patients with ERA, suggesting an important role of these parameters in the pathophysiology of ERA as well as in the accelerated atherosclerosis observed in these patients.

High postprandial triglyceridemia in patients with type 2 diabetes and microalbuminuria.

Microalbuminuria (MA) is an independent risk factor for atherosclerosis in patients with type 2 diabetes mellitus (T2DM). Postprandial lipemia is also associated with excess cardiovascular risk. However, the association between MA and postprandial lipemia in diabetes has not been investigated. A total of 64 patients with T2DM, 30 with and 34 without MA, were examined. Plasma total triglycerides (TGs), triglycerides contained in chylomicrons (CM-TG), and TGs in CM-deficient plasma were measured at baseline and every 2 h for 6 h after a mixed meal. Postheparin LPL and HL activities were also determined. Plasma levels of apolipoprotein A-V (apoA-V), apoC-II, and apoC-III were measured in the fasting state and 2 h postprandially. Patients with MA had higher postprandial total TG levels than those without MA (P < 0.001); this increase been attributed mainly to CM-TG. LPL activity and fasting concentrations of the measured apolipoproteins were not different between the studied groups, whereas HL activity was higher in the patients with MA. ApoC-II and apoC-III levels did not change postprandially in either study group, whereas apoA-V increased more in the patients with MA. These data demonstrate for the first time that MA is characterized by increased postprandial lipemia in patients with T2DM and may explain in part the excess cardiovascular risk in these patients.

Effects of eprosartan on serum metabolic parameters in patients with essential hypertension.

The effect of the anti-hypertensive drug eprosartan on metabolic parameters is currently not extensively documented. We evaluated the effect of eprosartan on parameters involved in atherogenesis, oxidative stress and clotting activity. This open-label unblinded intervention study included 40 adult patients with essential hypertension taking eprosartan. Eprosartan significantly reduced by 8% (p<0.001) the systolic and by 13% (p<.001) the diastolic blood pressure, and in-creased by 24% the time needed to produce oxidative by-products (p=0.001), a marker of oxidative stress. In contrast, ep-rosartan did not alter 8-isoprostane (8-epiPGF2a) levels, another marker of oxidative stress. Additionally, eprosartan re-duced by 14% aspartate aminotransferase and by 21% then alanine aminotransferase activity, while it had a neutral effect on the lipid profile and apolipoprotein levels and did not influence glucose homeostasis, creatinine and uric acid levels. Eprosartan did not affect the clotting/fibrinolytic status (estimated by plasminogen activator inhibitor 1, tissue plasmino-gen activator and a2 antiplasmin levels), or the enzymatic activity of the lipoprotein associated phospholipase A2 (Lp-PLA2) and paraoxonase 1 (PON1). In conclusion, eprosartan should be mainly considered as an anti-hypertensive agent with neutral effects on most of the metabolic parameters in hypertensive patients.

Oxidative stress is progressively enhanced with advancing stages of CKD.

BACKGROUND: Oxidative stress appears to have a central role in the pathophysiological process of uremia and its complications, including cardiovascular disease. However, there is little evidence to suggest how early oxidative stress starts developing during the progression of chronic kidney disease (CKD). The aim of this study is to assess oxidative stress activity in a cross-sectional study of patients with CKD stages 1 to 4. METHODS: Eighty-seven steady patients (47 men, 40 women) with a median age of 62 years (range, 28 to 84 years) and mean estimated glomerular filtration rate (eGFR) of 57 mL/min (0.95 mL/s) were studied. Levels of plasma 8-isoprostanes (8-epiPGF2a) and serum total antioxidant status (TAS) were used as markers of oxidative stress. 8-epiPGF2a levels were determined by using an enzyme-linked immunosorbent assay method, whereas a chromatometric method was used to determine TAS. RESULTS: Plasma 8-epiPGF2a levels increased significantly as CKD stages advanced (P < 0.001). There was a highly significant inverse correlation between 8-epiPGF2a level and GFR (P < 0.01). Serum TAS levels also increased in a similar fashion (P < 0.009) and showed a significant inverse correlation with GFR (P < 0.01). 8-epiPGF2a and TAS levels showed a positive correlation (P < 0.05). Multiple regression analysis showed that the most significant predictor variable for 8-epiPGF2a level was eGFR, whereas the association between eGFR and TAS was affected strongly by confounding variables, mainly uric acid level. CONCLUSION: Oxidative stress appears to increase as CKD progresses and correlates significantly with level of renal function. Increased TAS seems to be dependent on several confounding variables, including increased uric acid levels, and therefore does not seem to be a reliable method for assessing the antioxidant capacity of patients with CKD. These results suggest that larger studies using the correct markers to assess the timing and complex interplay of oxidative stress and other risk factors during the progression of CKD should be carried out.

Long-term treatment with EPO increases serum levels of high-density lipoprotein in patients with CKD.

BACKGROUND: Among lipid abnormalities observed in patients with chronic kidney disease (CKD) is a significant decrease in serum high-density lipoprotein cholesterol (HDL-C) levels. In a previously published randomized control trial, we showed that early erythropoietin (EPO) administration in a predialysis population slowed the progression of CKD. In the present nested substudy, we examine whether EPO has an influence on serum HDL-C levels in comparison to other lipid parameters in this population. METHODS: Eighty-eight patients with CKD stages 3 and 4 were enrolled in the study. Forty-five patients (group 1) were treated with EPO (50 U/kg/wk), targeting to increase hemoglobin levels to 13 g/dL or greater (>or=130 g/L). The other patients (group 2) remained without treatment until hemoglobin levels decreased to less than 9 g/dL (<90 g/L). The duration of the study was 12 months. RESULTS: At the end of the study, we observed a statistically significant decrease in serum levels of total cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides in both groups. However, serum HDL-C levels significantly increased in only group 1 (from 42.5 +/- 10.4 to 55.9 +/- 8.1 mg/dL [1.10 +/- 0.27 to 1.45 +/- 0.21 mmol/L]; P < 0.001), whereas they were unchanged in group 2. In addition, a significant decrease in atherogenic LDL-C/HDL-C ratio was observed in only group 1. Importantly, the increase in serum HDL-C levels correlated positively with the increase in hemoglobin values in EPO-treated patients. CONCLUSION: Our results show that EPO treatment of predialysis patients with CKD significantly increases serum HDL-C levels, which may represent an important antiatherogenic effect of this hormone.

Atherogenic lipid profile is a feature characteristic of patients with early rheumatoid arthritis: effect of early treatment--a prospective, controlled study.

We investigated lipid profiles and lipoprotein modification after immuno-intervention in patients with early rheumatoid arthritis (ERA). Fifty-eight patients with ERA who met the American College of Rheumatology (ACR) criteria were included in the study. These patients had disease durations of less than one year and had not had prior treatment for it. Smokers or patients suffering from diabetes mellitus, hypothyroidism, liver or kidney disease, Cushing's syndrome, obesity, familiar dyslipidemia and those receiving medications affecting lipid metabolism were excluded from the study. Sixty-three healthy volunteers (controls) were also included. Patients were treated with methotrexate and prednisone. Lipid profiles, disease activity for the 28 joint indices score (DAS-28) as well as ACR 50% response criteria were determined for all patients. The mean DAS-28 at disease onset was 5.8 +/- 0.9. After a year of therapy, 53 (91.3%) patients achieved the ACR 20% response criteria, while 45 (77.6%) attained the ACR 50% criteria. In addition, a significant decrease in the DAS-28, C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were observed. ERA patients exhibited higher serum levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and triglycerides, whereas their serum high-density lipoprotein cholesterol (HDL-C) levels were significantly lower compared to controls. As a consequence, the atherogenic ratio of TC/HDL-C as well as that of LDL-C/HDL-C was significantly higher in ERA patients compared to controls. After treatment, a significant reduction of the atherogenic ratio of TC/HDL-C as well as that of LDL-C/HDL-C was observed, a phenomenon primarily due to the increase of serum HDL-C levels. These changes were inversely correlated with laboratory changes, especially CRP and ESR. In conclusion, ERA patients are characterized by an atherogenic lipid profile, which improves after therapy. Thus, early immuno-intervention to control disease activity may reduce the risk of the atherosclerotic process and cardiovascular events in ERA patients.

PAF-acetylhydrolase activity in plasma of patients with chronic kidney disease. Effect of long-term therapy with erythropoietin.

BACKGROUND: Platelet activating factor acetylhydrolase (PAF-AH) is a Ca2+-independent phospholipase A2 that is secreted mainly from monocytes/macrophages. In human plasma, PAF-AH is associated primarily with low-density lipoprotein (LDL), while a small proportion of enzyme is associated with high-density lipoprotein (HDL). The ratio of HDL-PAF-AH to total plasma enzyme activity may represent a potential marker of atherogenicity. We evaluated possible alterations of lipoprotein-associated enzyme activity in Chronic Kidney Disease (CKD) patients, stages 3-4, and further investigated whether long-term therapy with recombinant human erythropoietin (epoetin) has any influence on the plasma PAF-AH activity in vivo or on the enzyme activity secreted from peripheral blood monocytes (PBMs), in vitro. METHODS: Forty-eight patients, 28 men and 20 women, with CKD (stages 3-4) participated in the study. Patients were randomized into groups I and II. Patients of group I (n = 28) were administered subcutaneously epoetin, 50 units/kg once per week. The Hb target was 13 g/dl. In group II (n = 20), epoetin was initiated only when the Hb levels decreased during follow-up to less than 9 g/dl. All patients were seen on an outpatient basis at 2, 4 and 6 months. Twenty-two normolipidemic age- and sex-matched healthy volunteers also participated in the study and were used as controls. RESULTS: The PAF-AH activity in plasma of both patient groups at baseline was higher compared to controls, whereas no difference in the HDL-PAF-AH activity was observed among the studied groups. Thus, the ratio of HDL-PAF-AH to the plasma enzyme activity was significantly lower in both patient groups compared to controls. Epoetin administration in the patients of group I was associated with a significant increase in the plasma PAF-AH and in HDL-PAF-AH activities 2 months after treatment, which remained stable for up to 6 months of therapy, a phenomenon not observed in untreated patients of group II. Thus, the ratio of HDL-PAF-AH to the plasma enzyme activity was significantly increased in patients of group I compared to the baseline values, a phenomenon not observed in patients of group II. In vitro treatment with epoetin of PBMs from patients of group I (undergoing therapy with epoetin) resulted in a dose-dependent increase in total and secreted enzyme activity, a phenomenon not observed in patients of group II who did not receive therapy with epoetin. This suggests that the in vivo increase in lipoprotein-associated PAF-AH observed in patients treated with epoetin may be attributed to the drug-induced enhanced secretion of PAF-AH from PBMs of these patients. CONCLUSIONS: CKD patients of stages 3-4 are characterized by an increase in plasma PAF-AH activity and a low ratio of HDL-PAF-AH to total plasma enzyme activity. Long-term therapy with epoetin may improve this atherogenic ratio thus this drug may play an important antiatherogenic role in CKD.

Erythrocyte PAF-acetylhydrolase activity in various stages of chronic kidney disease: effect of long-term therapy with erythropoietin.

BACKGROUND: Erythrocytes represent an important component of the antioxidant capacity of blood, comprising, in particular, intracellular enzymes, including platelet-activating factor acetylhydrolase (PAF-AH) and glutathione peroxidase (Gpx). We evaluated the erythrocyte PAF-AH and Gpx activities in various stages of chronic kidney disease (CKD), and further investigated whether erythropoietin (EPO) administration in these patients has any influence on the enzyme activities. METHODS: Thirty-six patients (19 men and 17 women) with CKD (stages 1 to 5) participated in the study. Thirteen of them presented with CKD stage 1 to 2 (group I), whereas 23 patients presented with CKD stage 3 to 5 and randomized into two groups (i.e., groups II and III). Patients of group II (N= 11) were administered EPO subcutaneously, 50 units per kg once per week. In group III (N= 12), EPO was initiated only when the hemoglobin (Hb) levels decreased during follow-up to less than 9 g/dL. All patients were seen on an outpatient basis at 2 and 4 months. Fifteen normolipidemic age- and sex-matched healthy volunteers also participated in the study and were used as controls. The PAF-AH and Gpx activities were determined in isolated washed erythrocytes. RESULTS: The erythrocyte-associated PAF-AH and Gpx activities were higher in all CKD patient groups at baseline compared to controls, the groups II and III exhibiting significantly higher enzyme activities compared with group I. In all studied populations, both enzyme activities were negatively correlated with the creatinine clearance values. Importantly, the PAF-AH and Gpx activities were progressively decreased during the follow-up in patients not treated with EPO (group III), a phenomenon not observed in patients receiving EPO (group II), or in patients of group I. This reduction in enzyme activities was positively correlated with the decrease in the creatinine clearance values in patients of group III. CONCLUSION: Significant alterations in the erythrocyte-associated PAF-AH and Gpx activities related to the disease stage are observed in CKD patients. Administration of EPO prevented the reduction in enzyme activities observed during the progression of the renal insufficiency, thus preserving the erythrocyte defense mechanisms against oxidative stress.

Alterations of paraoxonase and platelet-activating factor acetylhydrolase activities in patients on peritoneal dialysis.

OBJECTIVE: The more atherogenic lipid profile seen in peritoneal dialysis (PD) patients cannot fully explain the increased incidence of atherosclerosis in this population. Oxidative modification of low-density lipoproteins (LDL) is considered to play a central role in the atherogenic process, whereas high-density lipoprotein (HDL) protects LDL from oxidation. On the other hand, it has been suggested that the LDL and HDL of PD patients are more resistant to oxidation than those of control subjects, while PD-HDL equally protects LDL from oxidation compared to control-HDL. Two HDL-associated enzymes have been shown to protect both LDL and HDL from oxidation: paraoxonase (PON1) and HDL-associated platelet-activating factor acetylhydrolase (HDL-PAF-AH). Furthermore, low PON1 activity and high total plasma PAF-AH concentration, which represents mainly the LDL-associated enzyme, have been shown to be independent risk factors for coronary artery events in the general population. However, there are limited data regarding possible alterations of these enzymes in PD patients. The aim of our study was to examine the possible alterations of PON1 and PAF-AH activities in patients undergoing PD. DESIGN: A cross-sectional study. SETTING: A university medical center. PARTICIPANTS: 56 PD patients of Caucasian origin and 86 matched controls were studied. MEASUREMENTS: In all subjects, serum PON1 activity toward paraoxon (paraoxonase) and phenylacetate (arylesterase), as well as total serum and HDL-PAF-AH activities were measured; PON1 genetic polymorphisms known to influence PON1 activity (Q192R and M55L) were determined. RESULTS: The PD patients exhibited significantly increased serum PON1 (paraoxonase) and PON1 (arylesterase) activities compared to controls, regardless of the PON1 polymorphisms or the levels of HDL cholesterol. Additionally, PD patients had significantly elevated activities of total serum PAF-AH and HDL-PAF-AH, independently of the levels of LDL or HDL cholesterol. The ratio of HDL-PAF-AH/ total PAF-AH, which has recently been suggested to be a potential marker of atherogenicity, was decreased in these patients compared to controls. Moreover, no difference in the prevalence of PON1 polymorphisms between PD patients and controls was found. CONCLUSION: The elevated activities of PON1 and HDL-PAF-AH could explain the increased resistance of PD-HDL to oxidation; the higher activity of total PAF-AH and the decreased HDL-PAF-AH/ total PAF-AH ratio could contribute to the increased incidence of atherosclerosis in these patients.