Bernard Descomps

Simvastatin Prevents Angiotensin II–Induced Cardiac Alteration and Oxidative Stress

The influence of the HMG-CoA reductase inhibitor simvastatin was assessed on the cardiovascular alterations and production of free radicals associated with chronic angiotensin II (Ang II) infusion. Simvastatin (60 mg/kg per day PO) or placebo were given concomitantly for 10 days in Sprague-Dawley rats infused with Ang II (200 ng/kg per minute SC, osmotic pump). In addition, simvastatin or placebo was also given in vehicle-infused rats. Tail-cuff pressure and albuminuria were measured before and at the end of the treatment period. Cardiac weight, carotid structure, production of reactive oxygen species (ROS, by chemiluminescence) by polymorphonuclear leukocytes and aortic wall as well as protein and lipid oxidation products were determined at the end of the study. Ang II increased tail-cuff pressure by 56±12 mm Hg and simvastatin blunted the development of hypertension by ≈70% (19±5 mm Hg). Increases in heart weight index and carotid cross-sectional area induced by Ang II were obliterated by simvastatin (3.18±0.09 versus 3.46±0.11 mg/g body wt and 0.125±0.010 versus 0.177±0.010 mm2, respectively). The Ang II–induced increases in leukocyte and aortic production of ROS as well as protein and lipid oxidation products were prevented by simvastatin. No effect of simvastatin was detected in non–Ang II–infused rats. These results indicate that simvastatin prevented the development of hypertension and cardiovascular hypertrophy together with inhibition of the induced angiotensin II production of ROS. Therefore, inhibition of HMG CoA reductase by statins may have a beneficial effect on cardiovascular alterations through its antioxidant action in experimental Ang II–dependent hypertension.

Oxidative stress and lipid abnormalities in renal transplant recipients with or without chronic rejection

BACKGROUND The histological picture of chronic rejection with endothelial lesions and vascular hyperplasia resembles the early arteriosclerotic lesions. As increasing evidence suggests a role for oxidative stress in arteriosclerosis, we examined whether chronic rejection in renal transplant recipients was associated with increased oxidative stress markers. METHODS We investigated lipid metabolism and oxidative stress in 77 renal transplant recipients. Group I patients (n=34; 48+/-2 years old, 12 women, 22 men) had no clinical or histological signs of chronic rejection, whereas group II patients (n=43; 47+/-3 years old, 15 women, 28 men) had histologically proven chronic rejection. All patients were treated with cyclosporine and steroids. Lipid metabolism was evaluated by determining total cholesterol, triglycerides, high-density lipoprotein cholesterol, apolipoproteins AI and B, and lipoprotein (a). Oxidative stress was evaluated by determining: (i) the end product of lipid peroxidation, malonyldialdehyde (MDA), and erythrocyte polyunsaturated fatty acids; (ii) the nonenzymatic antioxidant system: erythrocyte alpha-tocopherol and glutathione; and (iii) the enzymatic antioxidant system: erythrocyte superoxide dismutase and plasma glutathione peroxidase. Results were compared with those of a control group (38 healthy volunteers). RESULTS Compared with controls, renal transplant recipients had significantly increased total cholesterol, triglyceride, and apolipoprotein B levels; they also had, in association with these lipid abnormalities, a significant increase in MDA and a significant decrease in erythrocyte polyunsaturated fatty acids, as well as a significant decrease in enzymatic and nonenzymatic antioxidant defense mechanisms. In contrast to lipid disturbances, where no difference was observed between groups I and II, markers of oxidative stress were significantly higher in group II compared with group I (MDA: 1.87+/-0.43 and 1.62+/-0.31 nmol/ml, respectively, P<0.05). The red blood cell antioxidative defense mechanisms were significantly decreased in group II compared with controls (erythrocyte alpha-tocopherol: 0.61+/-0.38 and 1.08+/-0.31 mg/L, respectively, P<0.01; superoxide dismutase: 1.08+/-0.2 and 1.32+/-0.31 U/mg Hb, respectively, P<0.01). CONCLUSION Our data show that oxidative stress with a decrease in antioxidant defenses is associated with kidney transplantation. In addition, oxidative stress markers are particularly increased in transplant recipients with chronic rejection, which suggests that oxidative stress may participate in the development and/or progression of vascular lesions observed in these patients.

Grape and grape seed extract capacities at protecting LDL against oxidation generated by Cu2+, AAPH or SIN-1 and at decreasing superoxide THP-1 cell production. A comparison to other extracts or compounds.

A large body of evidence supports the key role of oxidized low-density lipoprotein in atherosclerosis. The aim of this study was to compare the capacity of natural polyphenols (PP) from Vitis vinifera and Olea europea at protecting LDL against oxidation brought about by Cu 2+ , oxygen-centered radical-generating AAPH, or peroxynitrite-generating SIN-1 in vitro systems, or at impairing superoxide production in promonocyte cells (THP-1) conveniently differentiated into adherent macrophages. PP were either from the whole grape (fraction A) containing mainly procyanidins, (epi)-catechin and anthocyanins, or from grape seed extracts (fractions B and C) consisting of tannins and procyanidin oligomers with a higher content in B than in C, or from a grape skin extract (fraction D) consisting mainly of anthocyanins, or from a hydrosoluble olive mill wastewater PP extract (fraction E) containing hydroxytyrosol and oleuropein. Chlorogenic acid (F) and catechin (G) were taken as archetypes of PP preventing oxidation partly as copper scavenger and as radical scavenger only, respectively. All grape fractions were efficient towards Cu 2+ system (equally or more efficient than F), whereas they were rather poorly efficient towards AAPH and SIN-1 (less efficient than G but as efficient as F). Among the PP fractions, B was the most effective at protecting LDL in the SIN-1 system and at impairing THP-1 superoxide production. Taken together, these data suggest that the PP fraction from grape seed rich in procyanidins achieves the best compromise between the direct and indirect (i.e. cell-mediated) types of action in protecting LDL against oxidation, strengthening the need for improving the knowledge of its bioavailability in humans.

Red-wine beneficial long-term effect on lipids but not on antioxidant characteristics in plasma in a study comparing three types of wine--description of two O-methylated derivatives of gallic acid in humans.

The purpose of this double clinical study was (1) to evaluate the effect of one single intake (300 ml) of red wine (RW) on the plasma antioxidant capacity (pAOC) and plasma phenolics over the 24-h time period following the intake, and (2) to compare the long-term effects of daily intakes (250 ml/d) of RW, white wine (WW) and Champagne (CH) on the plasma and LDL characteristics of healthy sujects. In the first part, blood samples were collected just before and after wine consumption. In the second part, subjects received the 3 types of wine successively, only at the mealtime, over 3-week periods separated by a 3-week wash out. Blood samples were drawn in fasting condition before and after each 3-week wine consumption period. The peak of pAOC was at 3-4 h following the single intake of RW, that of catechin was at 4 h (0.13 μmol/l) and that of gallic acid and caffeic acid was earlier (≤⃒1.5 and 0.3 μmol/l, respectively). In plasma, the major form of gallic acid was 4-O-methylated, but a minor form (the 3-O-methyl derivative) appeared. In the long term study, no wine was able to change LDL oxidizability, but some other parameters were modified specifically: RW decreased pAOC (without changing TBARS and uric acid plasma levels), LDL lipids and total cholesterol (TC), and increased plasma apoA1, whereas CH increased plasma vitamin A. The beneficial effect of RW seems to mainly be explained by its action on lipid and lipoprotein constants, and not by its antioxidant one.

Monocyte superoxide production is inversely related to normal content of α-tocopherol in low-density lipoprotein

Vitamin E (alpha-tocopherol) is a potent peroxyl radical scavenger. According to the oxidative theory of atherosclerosis, it prevents oxidation of low-density lipoprotein (LDL) and thereby lowers the risk of cardiovascular disease. It also mediates cell actions, and specifically decreases monocyte superoxide anion-production (O2.--production), which is involved in LDL oxidation. We investigated whether alpha-tocopherol-containing LDL decreases this production in a manner dependent on the LDL alpha-tocopherol content (the alpha-tocopherol/apoB molar ratio) in human, phorbol ester-stimulated, adherent monocytes. We found that O2.--production was inhibited by native LDL (n-LDL) in a manner highly sensitive to the increasing alpha-tocopherol content (range 4.5 8). In addition: (1) inhibition was greater when alpha-tocopherol was associated to acetylated LDL (ac-LDL), the maximal percentage of inhibition being 80% as opposed to 35% for n-LDL; (2) the alpha-tocopherol overloading of either form of LDL did not produce further inhibition; (3) the free form of alpha-tocopherol produced lower inhibition compared with the lipoprotein-associated forms; (4) inhibition was not related to the cell content of alpha-tocopherol. We propose that the cell targeting of alpha-tocopherol is crucial to the inhibition of monocyte O2.--production, and thus that the role of normal LDL-alpha-tocopherol contents (range 6-8) in the prevention of atherogenic processes needs to be reexamined.

Relationships between Red Blood Cell Vitamin E and Polyunsaturated Fatty Acid in the Premature Infant

Low-birth-weight infants were fed breast milk (BM, n = 25) for 1 of 2 formulas containing 0.5 (PG, n = 32) or 1.7% fatty acids as alpha-linolenic acid (ALA)(ALA-PG, n = 31). Polyunsaturated fatty acids (PUFA) and alpha-tocopherol (alpha T) of RBC membrane phospholipids were measured at days 2 (D2) and 15 (D15) of enteral feeding, and at term. PUFA concentrations did not differ significantly between the 3 groups from D2 to term. The membrane integrity assessed by the alpha T/phospholipids ratio neither changed with time nor differed between formula groups. A metabolic relationship between alpha T and long-chain PUFA in RBC membranes was suggested by multiple regression analysis: alpha T showed a significant positive correlation with docosahexaenoic acid at D15 and term and with arachidonic acid at D15; the correlation with arachidonic acid tended toward significantly (p = 0.06) at term.

Biochemical, functional, and histochemical effects of essential fatty acid deficiency in rat kidney.

The present study was designed to examine the effects of EFA deficiency (EFAD) on biochemical, functional, and structural aspects of the kidney in growing and adult rats fed a normal or EFAD diet for 9 wk after weaning. Food and fluid intake (FI), urine volume, and Na+ and K+ excretions were measured weekly from weeks 4 to 8 by placing the rats in individual metabolic cages for 24 h. At week 9, Li+ and a 5% water load, respectively, were administered at 14 and 1.5 h prior to glomerular and proximal tubular function studies, as assessed by 3-h creatinine (CCr) and Li+ (CLi+) clearances. Hematocrit and urine volume; serum and urine [Cr], [Li+], [Na+], and [K+]; and renal FA distribution were also measured. Data [corrected to 100 g/body weight (bw) and presented as means ±SEM] were significant, at P<-0.05. Despite a similar ingestion of solids from weeks 4 to 7 (weeks 7 to 10 of life), the rats on the EFAD diet showed a decreased body weight from week 5. From weeks 4 to 8, Fl and urine volume were similar for both groups, but the Fl increased at week 6 in the EFAD group; 24-h Na+ and K+ excretions were similar at all weeks, except for an increase in the EFAD group for both ions at week 7. In the EFAD group, CCr and CLi+ decreased by 27 and 56.3%, respectively (385.7±33.4 vs. 280±21.1, and 21.0±2.1 vs. 9.2±1.1 μL/min/100 g; n=9 vs. 10), the latter result suggesting increased proximal reabsorption. The 3-h Na+ and K+ excretions were similar, but the Li+ decreased (0.78±0.06×10−2 vs. 0.32±0.03×10−2 μeq/min/100 g) in the EFAD group, giving additional support to the suggestion. Renal structure was normal and similar for both groups, but the EFAD group showed a more prominent proximal tubule brush border, together with heavier periodic acid-Schiff staining in all specimens from weeks 5 to 9. In the EFAD group, FA of the n−9 and n−7 series were higher, but most of the n−6 series were lower as a percentage of total lipids in the medulla and cortex. Medullary levels of 20∶4n−6 were maintained, 22∶4n−6 declined twice, arachidonic acid was maintained, and 20∶5n−3 was lower. The EFAD diet affected glomerular function, proximal tubular structure and function, and FA distribution in the rat kidney.

Apocynin decreases AGEs-induced stimulation of NF-κB protein expression in vascular smooth muscle cells from GK rats

Abstract Context: Elevated oxidative stress plays a key role in diabetes-associated vascular disease. Excessive production of reactive oxygen species via advanced glycation end products (AGEs) activates peroxisome proliferator-activated receptor gamma (PPARγ) and the transcription factor nuclear factor-kB (NF-κB) in aortic vascular smooth muscle cells (VSMCs). Apocynin, a drug with an antioxidant effect, has also been proposed as a therapeutic agent for atherosclerotic disease. Objectives: This work investigates the effects of apocynin on the PPARγ and NF-κB protein expression evoked by AGEs in cultured VSMCs from Goto–Kakisaki (GK) rats, a non-obese insulin model of both insulin resistance and type 2 diabetes. Materials and methods: VSMCs, isolated from aortas of GK and non-diabetic rats, were cultured. The expression of proteins was evaluated by Western blot. The blood glucose concentration was measured with a blood glucose test meter. The diabetes of GK rats was controlled by blood glucose and insulin determinations (non-fasting values). The serum insulin concentration was determined by radioimmunoassay. Results: In VSMCs from non-diabetic and GK rats, apocynin (1 and 10 µM) abolished the protein overexpression of NF-κB induced by glycated bovine serum albumin (AGEs-BSA) incubation. However, apocynin (1 and 10 µM) enhanced the expression of PPARγ protein in the presence of AGEs-BSA (100 μg/mL) in VSMCs from non-diabetic, but not from GK rats. Conclusion: These findings suggest that apocynin decreases the incidence of alterations in VSMCs induced by AGEs through the reduction of NF-κB and may represent an attractive therapeutic approach to treat diabetes mellitus.

Impairment of antioxidant defense mechanisms in elderly women without increase in oxidative stress markers: “A weak equilibrium”

The free radical theory of aging suggests that progressive defects in protection against free radicals allow tissue damage to occur. Concordant data have been observed in cell cultures or in animal models of aging. However, previous findings on antioxidant levels in human blood are somewhat conflicting according to the inclusion criteria (age, intercurrent diseases, habitus). Oxidative metabolism was investigated in 198 elderly healthy women more than 75 yr old (81.6 + 3.7; 75-99) living at home. Oxidative stress was evaluated by determining: the end product of lipid peroxidation, malondialdehyde (TBARS), and plasma and red blood cell (RBC) lipid content in polyunsaturated fatty acids (PUFA); nonenzymatic antioxidant system: plasma and RBC ot-tocopherol (pl Vit. E and RBC Vit. E), RBC glutathione (GSH); enzymatic antioxidant: RBC superoxide dismutase (SOD) and plasma glutathione peroxidase (GPx); and trace elements (copper, zinc, selenium). Nutritional status was monitored by body mass index, caloric intake, protein and lipid markers of malnutrition (albumin, prealbumin, retinol-binding protein, cholesterol, and triglycerides). Results were compared to a control group of 50 healthy young women (age range 20-45 yr). Despite reduced caloric intake (average 1582 kcal, range 697-3352), elderly women did not have any clinical (body mass index: 25 kg/m 2) or biological criteria of malnutrition: albumin (43.9 -+ 3.4 vs. 40.5 _+ 3.1 g/L; P < 0.001 ), prealburain (0.34 _+ 0.17 vs. 0.29 _+ 0,1 g/L; P < 0.01), retinol-binding protein (44.8 _+ 10 vs. 43.7 + 11 rag/L), cholesterol (6.13 +_ 1.1 vs. 5.12 _+ 0.95 mmol/L; P < 0.001), and triglycerides (1.18 + 0.56 vs. 0.99 _+ 0.45 mmol/L) were similar or increased in elderly vs. young women, respectively. When compared to healthy volunteers, SOD activity (I . 16 _+ 0.23 vs. 1.28 + 0.25 U/rag Hb, P < 0.01) and RBC GSH (4.32 + 1.10 vs. 4.69 -+ 1.06 nmol/mg Hb, P < 0.05) were significantly decreased, whereas pl Vit. E, RBC Vit. E, and GPx remained unchanged; copper (1.17 -+ 0.21 vs. 1.31 -+ 0.38 mg/L; P < 0,001) and zinc levels (0.86 + 0.16 vs. 0.94 _+ 0.16 rag/L; P < 0.01) were decreased; by contrast selenium levels were unaffected (75 _+ 22 vs. 80 + 17 ~tg/L). Despite these impairments in antioxidant defense mechanisms, we did not observe any increase in TBARS level ( l .26 +_ 0.36 vs. 1.34 + 0.37 mmol/L) or a decrease in PUFA content in plasma and RBC phospholipids. In healthy, well-nourished elderly populations, the impairment in antioxidant system did not result in an oxidative injury but in a precarious balance. This weak equilibrium could result in an increased susceptibility to reactive oxygen species and could be an underlying event for age-related diseases.