NADPH-oxidase activity and lipid peroxidation in neutrophils from rats fed fat-rich diets

Effects of whole flaxseed, raw soybeans, and calcium salts of fatty acids on measures of cellular immune function of transition dairy cows

The objective of the current study was to evaluate the effects of supplemental n-3 and n-6 fatty acid (FA) sources on cellular immune function of transition dairy cows. Animals were randomly assigned to receive 1 of 4 diets: control (n=11); whole flaxseed (n-3 FA source; n=11), 60 and 80g/kg of whole flaxseed [diet dry matter (DM) basis] during pre- and postpartum, respectively; whole raw soybeans (n-6 FA source; n=10), 120 and 160g/kg of whole raw soybeans (diet DM basis) during pre- and postpartum, respectively; and calcium salts of unsaturated FA (Megalac-E, n-6 FA source; n=10), 24 and 32g/kg of calcium salts of unsaturated FA (diet DM basis) during pre- and postpartum, respectively. Supplemental FA did not alter DM intake and milk yield but increased energy balance during the postpartum period. Diets containing n-3 and n-6 FA sources increased phagocytosis capacity of leukocytes and monocytes and phagocytosis activity of monocytes. Furthermore, n-3 FA source increased phagocytic capacity of leukocytes and neutrophils and increased phagocytic activity in monocytes and neutrophils when compared with n-6 FA sources. Supplemental FA effects on adaptive immune system included increased percentage of T-helper cells, T-cytotoxic cells, cells that expressed IL-2 receptors, and CD62 adhesion molecules. The results of this study suggest that unsaturated FA can modulate innate and adaptive cellular immunity and trigger a proinflammatory response. The n-3 FA seems to have a greater effect on phagocytic capacity and activity of leukocytes when compared with n-6 FA.

New Trends on Antineoplastic Therapy Research: Bullfrog (Rana catesbeiana Shaw) Oil Nanostructured Systems

Bullfrog oil is a natural product extracted from the Rana catesbeiana Shaw adipose tissue and used in folk medicine for the treatment of several diseases. The aim of this study was to evaluate the extraction process of bullfrog oil, to develop a suitable topical nanoemulsion and to evaluate its efficacy against melanoma cells. The oil samples were obtained by hot and organic solvent extraction processes and were characterized by titration techniques and gas chromatography mass spectrometry (GC-MS). The required hydrophile-lipophile balance and the pseudo-ternary phase diagram (PTPD) were assessed to determine the emulsification ability of the bullfrog oil. The anti-tumoral activity of the samples was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for normal fibroblast (3T3) and melanoma (B16F10) cell lines. Both extraction methods produced yielded around 60% and the oil was mainly composed of unsaturated compounds (around 60%). The bullfrog oil nanoemulsion obtained from PTPD presented a droplet size of about 390 nm and polydispersity = 0.05 and a zeta potential of about -25 mV. Both the bullfrog oil itself and its topical nanoemulsion did not show cytotoxicity in 3T3 linage. However, these systems showed growth inhibition in B16F10 cells. Finally, the bullfrog oil presented itself as a candidate for the development of pharmaceutical products free from cytotoxicity and effective for antineoplastic therapy.

Effect of dietary fats on oxidative-antioxidative status of blood in rats

This study was performed to examine the effect of different fat sources, lard, sunflower oil (SO), and fish oil (FO) in high-fat and low-fat diet on reactive oxygen species generation by blood phagocytes, glutathione redox status in erythrocytes, and total plasma antioxidant ability in rats. Whole blood chemiluminescence (CL) did not differ between three low-fat fed groups. However, baseline and phorbol myristate acetate (PMA)-stimulated CL in blood of high-lard fed rats were lower than in low-lard and high-SO fed animals. Phagocyte-stimulated oxidative burst was higher in rats fed high-SO diet than in those fed low-SO and high-FO diets. The highest level of oxidize glutathione (GSSH), the lowest reduce glutathione (GSH)/GSSG ratio in erythrocytes, and the highest plasma activity to reduce ferric ions were observed in rats fed both diets contaning linoleic acid-rich sunflower oil compared to animals fed the corresponding energy from other fats. 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity of plasma was lower in high-lard and high-FO fed rats compared to the corresponding low-fat diets, and the lowest in low-FO fed rats among low-fat fed animals. We presume from our results that linoleic acid may have dual effect, prooxidative in blood cells but maintaining total antioxidant plasma ability.

Changes in plasma free fatty acid levels in septic patients are associated with cardiac damage and reduction in heart rate variability

Free fatty acids (FFAs) have been shown to produce alteration of heart rate variability (HRV) in healthy and diabetic individuals. Changes in HRV have been described in septic patients and in those with hyperglycemia and elevated plasma FFA levels. We studied if sepsis-induced heart damage and HRV alteration are associated with plasma FFA levels in patients. Thirty-one patients with sepsis were included. The patients were divided into two groups: survivors(n = 12) and nonsurvivors (n = 19). The following associations were investigated: (a) troponin I elevation and HRV reduction and (b) clinical evolution and HRV index, plasma troponin, and plasma FFA levels. Initial measurements of C-reactive protein and gravity Acute Physiology and Chronic Health Evaluation scores were similar in both groups. Overall, an increase in plasma troponin level was related to increased mortality risk. From the first day of study, the nonsurvivor group presented a reduced left ventricular stroke work systolic index and a reduced low frequency (LF) that is one of HRV indexes. The correlation coefficient for LF values and troponin was r(2) = 0.75 (P < 0.05). All patients presented elevated plasma FFA levels on the first day of the study (5.11 +/- 0.53 mg/mL), and this elevation was even greater in the nonsurvivor group compared with the survivors (6.88 +/- 0.13 vs. 3.85 +/- 0.48 mg/mL, respectively; P < 0.05). Cardiac damage was confirmed by measurement of plasma troponin I and histological analysis. Heart dysfunction was determined by left ventricular stroke work systolic index and HRV index in nonsurvivor patients. A relationship was found between plasma FFA levels, LFnu index, troponin levels, and histological changes. Plasma FFA levels emerged as possible cause of heart damage in sepsis.

Effect of fish or soybean oil-rich diets on bradykinin, kallikrein, nitric oxide, leptin, corticosterone and macrophages in carrageenan stimulated rats

We have previously demonstrated that both n-3 and n-6 polyunsaturated fatty acids (PUFA)-rich diets decrease the acute inflammatory response partially explained by the high corticosterone basal levels. The present study aimed to determine the effect of hyperlipidic diets (PUFA n-3 or n-6) on phagocytosis, hydrogen peroxide (H(2)O(2)) and nitric oxide (NO) release by macrophages, bradykinin (BK) and NO release in the paw inflammatory perfusate and Kallikrein (KK), corticosterone and leptin blood levels. Hyperlipidic diets decreased H(2)O(2) release from macrophages stimulated by carrageenan or phorbol-miristate-acetate (PMA), NO release from macrophage stimulated by carrageenan, BK and NO release in the edema perfusate, KK plasma levels and the increase of serum leptin after carrageenan stimulus. These data show that both fish and soybean oil-rich diets promote similar alterations on inflammatory mediators of carrageenan edema and a causal association with the anti-inflammatory effect of these diets.

Lipid peroxidation, oxidative stress genes and dietary factors in breast cancer protection: a hypothesis

We have recently proposed that lipid peroxidation may be a common mechanistic pathway by which obesity and hypertension lead to increased renal cell cancer risk. During this exercise, we noted a risk factor swap between breast and kidney cancer (oophorectomy and increased parity, detrimental for kidney, beneficial for breast; high blood pressure, detrimental for kidney, beneficial for breast when it occurs during pregnancy; alcohol, beneficial for kidney, detrimental for breast, and so on). We have subsequently proposed the hypothesis that lipid peroxidation represents a protective mechanism in breast cancer, and reviewed the evidence of the role of lipid peroxidation on established hormonal and non-hormonal factors for breast cancer. Here, we review the evidence in support of lipid peroxidation playing a role in the relationships between dietary factors and breast cancer. Available evidence implicates increased lipid peroxidation products in the anti-carcinogenic effect of suspected protective factors for breast cancer, including soy, marine n-3 fatty acids, green tea, isothiocyanates, and vitamin D and calcium. We also review the epidemiological evidence supporting a modifying effect of oxidative stress genes in dietary factor-breast cancer relationships.

Role of insulin on PGE2 generation during LPS-induced lung inflammation in rats

Alterations in arachidonic acid (AA) metabolism have been reported to occur in diabetes mellitus. The present study was carried out to verify if these alterations are due to the relative lack of insulin or to high levels of blood glucose. Male Wistar rats were rendered diabetic by alloxan injection (42 mg/kg, i.v.), 10 or 30 days before the experiments. Some diabetic rats received a single dose (4 IU, s.c.) of NPH insulin 2 h before an intratracheal instillation of lipopolysaccharide (LPS, 750 microg) or saline. Six hours after LPS challenge, the following parameters were analysed: blood glucose levels, total and differential leukocyte counts in bronchoalveolar lavage (BAL) fluid; linoleic acid and AA content in blood neutrophils (HPLC), and levels of prostaglandin (PG)E(2) in BAL (ELISA). Relative to controls, a reduced number of neutrophils (18%) and decreased amounts of PGE(2) (40%) were observed in the BAL fluid of diabetic rats in response to LPS. A single dose of insulin was not able to reduce blood sugar levels to normal values, but instead resulted in the normalization of both leukocyte migration to the lungs and levels of PGE(2). Accordingly, these abnormalities might be primarily linked to a continuing insulin deficiency rather than to secondary hyperglycaemia occurring in the diabetic rat. In conclusion, data presented suggest that insulin might regulate neutrophil migration and generation of PGE(2) during the course of acute lung injury induced by LPS.

Role of Lipid Peroxidation in the Epidemiology and Prevention of Breast Cancer

We have recently proposed a common mechanistic pathway by which obesity and hypertension lead to increased renal cell cancer risk. Our hypothesis posits lipid peroxidation, which is a principal mechanism in rodent renal carcinogenesis, as an intermediate step that leads to a final common pathway shared by numerous observed risks (including obesity, hypertension, smoking, oophorectomy/hysterectomy, parity, preeclampsia, diabetes, and analgesics) or protective factors (including oral contraceptive use and alcohol) for renal cell cancer [Cancer Causes Control 2002;13:287-93]. During this exercise, we have noticed how certain risk factors for renal cell carcinoma are protective for breast cancer and how certain protective factors for renal cell carcinoma increase risk for breast cancer. Parity and oophorectomy, for example, are positively associated with renal cell carcinoma but are negatively associated with breast cancer. Similarly, obesity and hypertension are positively associated with renal cell carcinoma, but obesity is negatively associated with breast cancer in premenopausal women and hypertension during pregnancy is negatively associated with breast cancer. Furthermore, alcohol intake, negatively associated with renal cell carcinoma, is also positively associated with breast cancer. We propose here the possibility that lipid peroxidation may represent a protective mechanism in breast cancer. Although this runs counter to the conventional view that lipid peroxidation is a process that is harmful and carcinogenic, we present here the chemical and biological rationale, based on epidemiologic and biochemical data, which may deserve further consideration and investigation.

Genes regulated by arachidonic and oleic acids in Raji cells

FA are known to modulate immune function in conditions such as arthritis and lupus erythematosus. The effects of arachidonic (AA) and oleic acids (OA) on function and pleiotropic gene expression of Raji cells were investigated. The following parameters were evaluated: cytotoxicity as assessed by loss of membrane integrity and DNA fragmentation; proliferation as measured by [14C]thymidine incorporation; production of interleukin (IL)-10, interferon (INF)-gamma, and tumor necrosis factor (TNF)-alpha; and expression of pleiotropic genes by a macroarray technique (83 genes in total). AA was more toxic to Raji cells than OA. Both FA promoted an increase in Raji cell proliferation at 75 microM, whereas OA at high concentrations (200 microM) decreased proliferation. AA reduced the production of IL-10, TNF-alpha, and INF-gamma. On the other hand, OA provoked an increase of INF-gamma production but did not affect the production of IL-10 and TNF-alpha. The proportions of genes with altered expression were 27% for AA and 35% for OA. The FA affected the expression of genes clustered as: cytokines, signal transduction pathways, transcription factors, cell cycle, defense and repair, apoptosis, DNA synthesis, cell adhesion, cytoskeleton, and hormone receptors. The most remarkable changes were observed in the genes of signal transduction pathways. These results led us to conclude that the effect of these FA on B-lymphocytes includes regulation of gene expression. Thus, diets enriched with fat containing OA or AA may affect B lymphocyte function in vivo.

NAD(P)H oxidase p22phox Gene C242T polymorphism and lipoprotein oxidation

BACKGROUND

Vascular NAD(P)H oxidase is a key enzyme of superoxide anion production in human vessel walls. The C242T mutation in the CYBA gene coding for p22phox, a component of the enzyme, may change the redox state. The aim of this study was to evaluate the influence of the polymorphism on serum concentrations of oxidative stress markers.

METHODS

Serum samples were collected from 134 Type 2 diabetic patients and analyzed for oxidized high-density lipoprotein (HDL) by in-house ELISA, and oxidized low-density lipoprotein (LDL) and thiobarbituric acid reactive substance (TBARS) by commercial kits. For genotyping, the Taqman PCR method was adapted to detect the polymorphism.

RESULTS

Circulating concentrations of oxidized HDL were about 1.5-fold lower in those of the CT/TT genotypes than the CC genotype [3.3 +/- 0.3 and 5.0 +/- 0.3 U/dl (mean +/- S.E.M.), respectively; multiple regression analysis, p=0.006], whereas concentrations of oxidized LDL were slightly greater (1.1-fold, p=0.01) in those with the CT/TT genotypes. However, no significant difference was observed in TBARS between the genotypes.

CONCLUSIONS

The effect was inconsistent among the markers, but these results suggest that the CYBA C242T polymorphism is involved in NAD(P)H oxidase activity and affects oxidation of lipoproteins by altering the redox state in the vasculature.

Effect of dexamethasone on neutrophil metabolism

The effect of dexamethasone on glucose and glutamine metabolism was investigated. The consumption and oxidation of glucose and glutamine, and the production of glutamate and lactate were determined in neutrophils cultured for 3 h in the presence of dexamethasone. The activities and expression of glucose-6-phosphate dehydrogenase (G6PDH) and phosphate-dependent glutaminase were also determined under the same conditions. Addition of dexamethasone to the culture medium caused a significant increase of glucose consumption at 0.5 microm (123.9%) and 1.0 microm (78.3%) concentrations. In spite of this, however, glucose oxidation remained unchanged. The glucocorticoid did not change glutamine consumption but caused a significant increase of glutamate production and did not alter glutamine oxidation. Dexamethasone-treated neutrophils had a significant decrease of G6PDH activity and expression in particular at 1.0 microm concentration. Phosphate- dependent glutaminase activity was also decreased (about 34%) by dexamethasone treatment. A similar effect was observed on glutaminase expression as indicated by RT-PCR analysis. Thus, the effect of dexamethasone on neutrophil metabolism was particularly noticeable with respect to G6PDH and glutaminase activities where a decrease in the respective mRNA levels was demonstrated.

Iron overload in hypercholesterolemic rats affects iron homeostasis and serum lipids but not blood pressure

Epidemiologic and experimental data suggest that excess iron may contribute to the development of cardiovascular diseases (CVD). Because increased LDL cholesterol, decreased HDL cholesterol and alteration of systolic blood pressure (SBP) have all been implicated as risk factors for atherosclerosis and related CVD, the present study was designed to determine whether excess iron alters serum lipids and SBP in control and hypercholesterolemic rats. Female Fischer rats were divided into four groups. The control group (C) was fed the control diet, the CI group was fed the control diet and given iron dextran injections, the hypercholesterolemic group (H) was fed a 1 g/100 g cholesterol diet, and the HI group was fed the cholesterol diet and given iron dextran injections. The rats were fed the diets for 8 wk and iron dextran injections were given during wk 6 at doses of 10 mg/d for 5 d. Excess iron reduced (P < 0.01) plasma total cholesterol in rats fed the cholesterol diet (5.31 +/- 0.83 and 3.17 +/- 0.31 mmol/L for H and HI, respectively). Excess iron also resulted in a redistribution of cholesterol among the various lipoprotein fractions, with an increase (P < 0.01) in HDL cholesterol (0.56 +/- 0.12 and 0.85 +/- 0.16 mmol/L for H and HI, respectively) and a decrease (P < 0.01) in LDL cholesterol (4.49 +/- 0.77 and 2.09 +/- 0.26 mmol/L for H and HI, respectively). This redistribution also occurred in the rats fed the control diet. The treatments did not affect SBP or heart rate. The high cholesterol diet affected iron homeostasis; group H had lower transferrin saturation than group C (P < 0.01); group HI had a lower serum iron concentration than group CI but did not differ from group H (P < 0.05). Therefore, we conclude that if iron has any effect on CVD, it is not through its influence on serum lipids and blood pressure.

Evidence that glutamine is involved in neutrophil function

Phosphate-dependent glutaminase (PDG) activity, a key enzyme of glutamine metabolism, was determined in neutrophils obtained from the intra-peritoneal cavity (PC) or bronchoalveolar space (BAS) after administration of 1 ml or 100 microl, respectively of saline, glycogen solution (1%) or lipopolysaccharide (LPS 0.1 mg (100 microl)(-1)). Neutrophils were obtained by lavage of both sites with 20 ml saline 24 h after the administration of the stimuli. Glycogen and LPS, depending on the site the cells were obtained from, differently modulated PDG activity. Cells from BAS stimulated by glycogen or LPS had raised PDG activity to 30.5 +/- 5.2 and 42.7 +/- 12.1 nmol min(-1) mg(-1) protein, respectively, when compared with saline (9.1 +/- 0.9 nmol min(-1) mg(-1) protein); mean +/- SEM. On the other hand, cells from PC showed different PDG activity: 52.0 +/- 12.6 nmol min(-1) mg(-1) for saline, 36.5 +/- 9.5 nmol min(-1) mg(-1) for glycogen, and 76.6 +/- 11.2 nmol min(-1) mg(-1) for LPS; mean +/- SEM. Therefore, PDG activity varies with the site from which neutrophils are obtained and the stimulus imposed. The effect of glutamine on nitric oxide (NO) and tumour necrosis factor (TNF) production by peritoneal neutrophils, obtained after glycogen administration, cultured in the presence of LPS (0.5 microg ml(-1)) was also examined. The addition of glutamine at concentrations varying from 2 to 20 mM did not markedly affect NO production. Glutamine alone at 2 mM did not modify the production of TNF but in the presence of LPS caused a significant decrease. So, glutamine may preserve the function of neutrophils during infections and injuries.

Postprandial oxidative stress

Consumption of a meal containing oxidized and oxidizable lipids gives rise to an increased plasma concentration of lipid hydroperoxides, detectable by a sensitive chemiluminescence procedure. This is associated with increased susceptibility of LDL to oxidation, apparently due a structural perturbation at the particle surface brought about by lipid oxidation products. The postprandial modification of LDL is at least partially accounted for by an increase of LDL-, a subfraction containing lipid oxidation products where apoprotein-B-100 (apoB-100) is denatured. Consuming the meal with a suitable source of antioxidants, such as those found in red wine, minimizes this postprandial oxidative stress. The inhibition of peroxidation of lipids present in the meal during digestion is a possible mechanism for the observed protection of LDL. The in vivo oxidatively modified LDL- has numerous features that correspond to the atherogenic minimally modified LDL produced in vitro. These modified particles could account for a relevant link between nutrition and early biological processes that foster the development of atherosclerosis.

Fiber-rich diets alter rat intestinal leukocytes metabolism

This study addressed the following question: What is the effect of fermentable and nonfermentable fiber-rich diets on intestinal immune cells' function and metabolism? For this purpose, weaning rats received, for 8 weeks, two types of fiber-enriched (30%) diets with different fermentable/nonfermentable fiber ratios, that is, oat bran (0.3) and wheat bran (0.14). The results of these two experimental groups were compared with those of the low-fiber control group having a 0.22 fermentable/nonfermentable fiber ratio. The total number and proportion of leukocytes in plasma, total number of cells in the lymphoid organs, lymphocyte proliferative activity and capacity of phagocytosis, hydrogen peroxide production, and adherence of macrophages were investigated. The activities of key enzymes of glycolysis and glutaminolysis, and of the Krebs cycle of lymphocytes from the mesenteric lymph nodes and macrophages from the intraperitoneal cavity were determined. The metabolic response of lymphocytes and macrophages from rats fed the three diets to Bacillus Calmette-Guérin-stimulus was also investigated. The number of lymphocytes in the mesenteric lymph nodes was lower in both fiber-rich diets than in the control but did not have any difference in the remaining lymphoid organs. Wheat bran caused a significant reduction in the phagocytosis capacity and adherence index of macrophages, whereas oat bran did not have a significant effect. The response of glucose and glutamine metabolism to Bacillus Calmette-Guérin-stimulus was not altered by the diets in lymphocytes, whereas in macrophages, the increase in glutaminase and hexokinase activities was abolished.