Modulation of human neutrophil oxidative metabolism and degranulation by extract of Tamarindus indica L. fruit pulp

The tamarind (Tamarindus indica L) is indigenous to Asian countries and widely cultivated in the American continents. The tamarind fruit pulp extract (ExT), traditionally used in spices, food components and juices, is rich in polyphenols that have demonstrated anti-atherosclerotic, antioxidant and immunomodulatory activities. This study evaluated the modulator effect of a crude hydroalcoholic ExT on some peripheral human neutrophil functions. The neutrophil reactive oxygen species generation, triggered by opsonized zymosan (OZ), n-formyl-methionyl-leucyl-phenylalanine (fMLP) or phorbol myristate acetate (PMA), and assessed by luminol- and lucigenin-enhanced chemiluminescence (LumCL and LucCL, respectively), was inhibited by ExT in a concentration-dependent manner. ExT was a more effective inhibitor of the PMA-stimulated neutrophil function [IC(50) (in mu g/10(6)cells) = 115.7 +/- 9.7 (LumCL) and 174.5 +/- 25.9 (LucCL)], than the OZ- [IC(50) = 248.5 +/- 23.1 (LumCL) and 324.1 +/- 34.6 (LucCL)] or fMLP-stimulated cells [IC(50) = 178.5 +/- 12.2 (LumCL)]. The ExT also inhibited neutrophil NADPH oxidase activity (evaluated by O(2) consumption), degranulation and elastase activity (evaluated by spectrophotometric methods) at concentrations higher than 200 mu g/10(6) cells, without being toxic to the cells, under the conditions assessed. Together, these results indicate the potential of ExT as a source of compounds that can modulate the neutrophil-mediated inflammatory diseases. (C) 2008 Elsevier Ltd. All rights reserved.

Inhibition of immune complex-mediated neutrophil oxidative metabolism: A pharmacophore model for 3-phenylcoumarin derivatives using GRIND-based 3D-QSAR and 2D-QSAR procedures

In this study, twenty hydroxylated and acetoxylated 3-phenylcoumarin derivatives were evaluated as inhibitors of immune complex-stimulated neutrophil oxidative metabolism and possible modulators of the inflammatory tissue damage found in type III hypersensitivity reactions. By using lucigenin- and luminol-enhanced chemiluminescence assays (CL-luc and CL-lum, respectively), we found that the 6,7-dihydroxylated and 6,7-diacetoxylated 3-phenylcoumarin derivatives were the most effective inhibitors. Different structural features of the other compounds determined CL-luc and/or CL-lum inhibition. The 2D-QSAR analysis suggested the importance of hydrophobic contributions to explain these effects. In addition, a statistically significant 3D-QSAR model built applying GRIND descriptors allowed us to propose a virtual receptor site considering pharmacophoric regions and mutual distances. Furthermore, the 3-phenylcoumarins studied were not toxic to neutrophils under the assessed conditions. (C) 2007 Elsevier Masson SAS. All rights reserved.

The role of seasonality on the inhibitory effect of Brazilian green propolis on the oxidative metabolism of neutrophils

The reactive oxygen species (ROS) produced by neutrophils are involved in the pathogenesis of several diseases, for which the intake of antioxidants could benefit patients either as a prophylactic or therapeutic treatment. Propolis is among the known antioxidants, and its chemical composition may vary under the influence of seasonality, which may interfere in its biological properties. This work evaluates the role of seasonality on the production of some important compounds of propolis samples produced monthly from November 2001 through October 2002 as well as the effect of these samples on the oxidative metabolism of stimulated neutrophils, by using both luminol and lucigenin to produce chemiluminescence (CLlum and CLluc, respectively). The cytotoxicity of the most active extracts to neutrophils was also investigated. The inhibitory effect of the propolis samples varied significantly during the studied period for both assays (3.4 +/- 1.1 to 16.0 +/- 1.1 mu g/mL for CLlum and 6.2 +/- 2.0 to 30.0 +/- 5.0 mu g/mL for CLluc), which was also observed in the quantitative profile of the main analyzed compounds (aromadendrin-4`-methyl ether, artepillin C, and baccharin). This effect started to become more prominent during the fall and, among all the studied extracts, the one obtained in May displayed the highest inhibitory effect on CL production (3.4 +/- 1.1 mu g/mL for alum and 6.2 +/- 2.0 mu g/mL for CLluc). The HPLC qualitative profiles of the extracts of propolis samples were quite similar, but there was a huge variation in terms of quantitative profile. It seems that aromadendrin-4`-methyl ether and baccharin play an essential role in the antioxidant activity, while artepillin C is not very important for this effect. The extracts presenting the highest antioxidant activity were produced in May, June, and August, and they did not display cytotoxicity at 25 mu g/mL; quercetin, used as control, was not toxic to neutrophils at 8.5 mu g/mL (C) 2010 Elsevier B.V. All rights reserved.

Glutamate Transport Decreases Mitochondrial pH and Modulates Oxidative Metabolism in Astrocytes.

During synaptic activity, the clearance of neuronally released glutamate leads to an intracellular sodium concentration increase in astrocytes that is associated with significant metabolic cost. The proximity of mitochondria at glutamate uptake sites in astrocytes raises the question of the ability of mitochondria to respond to these energy demands. We used dynamic fluorescence imaging to investigate the impact of glutamatergic transmission on mitochondria in intact astrocytes. Neuronal release of glutamate induced an intracellular acidification in astrocytes, via glutamate transporters, that spread over the mitochondrial matrix. The glutamate-induced mitochondrial matrix acidification exceeded cytosolic acidification and abrogated cytosol-to-mitochondrial matrix pH gradient. By decoupling glutamate uptake from cellular acidification, we found that glutamate induced a pH-mediated decrease in mitochondrial metabolism that surpasses the Ca(2+)-mediated stimulatory effects. These findings suggest a model in which excitatory neurotransmission dynamically regulates astrocyte energy metabolism by limiting the contribution of mitochondria to the metabolic response, thereby increasing the local oxygen availability and preventing excessive mitochondrial reactive oxygen species production.

Stimulation-induced increases of astrocytic oxidative metabolism in rats and humans investigated with 1-11C-acetate

The purpose of this study was to investigate astrocytic oxidative metabolism using 1-(11)C-acetate. 1-(11)C-acetate kinetics were evaluated in the rat somatosensory cortex using a beta-scintillator during different manipulations (test-retest, infraorbital nerve stimulation, and administration of acetazolamide or dichloroacetate). In humans a visual activation paradigm was used and kinetics were measured with positron emission tomography. Data were analyzed using a one-tissue compartment model. The following features supported the hypothesis that washout of radiolabel (k(2)) is because of (11)C-CO(2) and therefore related to oxygen consumption (CMRO(2)): (1) the onset of (11)C washout was delayed; (2)k(2) was not affected by acetazolamide-induced blood flow increase; (3)k(2) demonstrated a significant increase during stimulation in rats (from 0.014+/-0.007 to 0.027+/-0.006 per minute) and humans (from 0.016+/-0.010 to 0.026+/-0.006 per minute); and (4) dichloroacetate led to a substantial decrease of k(2). In the test-retest experiments K(1) and k(2) were very stable. In summary, 1-(11)C-acetate seems a promising tracer to investigate astrocytic oxidative metabolism in vivo. If the washout rate indeed represents the production of (11)C-CO(2), then its increase during stimulation would point to a substantially higher astrocytic oxidative metabolism during brain activation. However, the quantitative relationship between k(2) and CMRO(2) needs to be determined in future experiments.

Interleukin-15 augments oxidative metabolism and fungicidal activity of human monocytes against Paracoccidioides brasiliensis

Interleukin (IL)-15 is a pleiotropic cytokine that regulates the proliferation and survival of many cell types. IL-15 is produced by monocytes and macrophages against infectious agents and plays a pivotal role in innate and adaptive immune responses. This study analyzed the effect of IL-15 on fungicidal activity, oxidative metabolism and cytokine production by human monocytes challenged in vitro with Paracoccidioides brasiliensis (Pb18), the agent of paracoccidioidomycosis. Peripheral blood monocytes were pre-incubated with IL-15 and then challenged with Pb18. Fungicidal activity was assessed by viable fungi recovery from cultures after plating on brain-heart infusion-agar. Superoxide anion (O2-), hydrogen peroxide (H2O2), tumour necrosis factor-alpha (TNF-α), IL-6, IL-15 and IL-10 production by monocytes were also determined. IL-15 enhanced fungicidal activity against Pb18 in a dose-dependent pattern. This effect was abrogated by addition of anti-IL-15 monoclonal antibody. A significant stimulatory effect of IL-15 on O2- and H2O2 release suggests that fungicidal activity was dependent on the activation of oxidative metabolism. Pre-treatment of monocytes with IL-15 induced significantly higher levels of TNF-α, IL-10 and IL-15 production by cells challenged with the fungus. These results suggest a modulatory effect of IL-15 on pro and anti-inflammatory cytokine production, oxidative metabolism and fungicidal activity of monocytes during Pb18 infection.

Retinoblastoma Protein Knockdown Favors Oxidative Metabolism and Glucose and Fatty Acid Disposal in Muscle Cells.

Deficiency in the retinoblastoma protein (Rb) favors leanness and a healthy metabolic profile in mice largely attributed to activation of oxidative metabolism in white and brown adipose tissues. Less is known about Rb modulation of skeletal muscle metabolism. This was studied here by transiently knocking down Rb expression in differentiated C2C12 myotubes using small interfering RNAs. Compared with control cells transfected with non-targeting RNAs, myotubes silenced for Rb (by 80-90%) had increased expression of genes related to fatty acid uptake and oxidation such as Cd36 and Cpt1b (by 61% and 42%, respectively), increased Mitofusin 2 protein content (∼2.5-fold increase), increased mitochondrial to nuclear DNA ratio (by 48%), increased oxygen consumption (by 65%) and decreased intracellular lipid accumulation. Rb silenced myotubes also displayed up-regulated levels of glucose transporter type 4 expression (∼5-fold increase), increased basal glucose uptake, and enhanced insulin-induced Akt phosphorylation. Interestingly, exercise in mice led to increased Rb phosphorylation (inactivation) in skeletal muscle as evidenced by immunohistochemistry analysis. In conclusion, the silencing of Rb enhances mitochondrial oxidative metabolism and fatty acid and glucose disposal in skeletal myotubes, and changes in Rb status may contribute to muscle physiological adaptation to exercise. J. Cell. Physiol. 231: 708-718, 2016. © 2015 Wiley Periodicals, Inc.

Acid-base Balance and Oxidative Metabolism in Calcified Tissues

The calcified tissues, comprising bone and cartilage, are metabolically active tissues that bind and release calcium, bicarbonate and other substances according to systemic needs. Understanding the regulation of cellular metabolism in bone and cartilage is an important issue, since a link between the metabolism and diseases of these tissues is clear. An essential element in the function of bone-resorbing osteoclasts, namely regulation of bicarbonate transport, has not yet been thoroughly studied. Another example of an important but at the same time fairly unexplored subject of interest in this field is cartilage degeneration, an important determinant for development of osteoarthritis. The link between this and oxidative metabolism has rarely been studied. In this study, we have investigated the significance of bicarbonate transport in osteoclasts. We found that osteoclasts possess several potential proteins for bicarbonate transport, including carbonic anhydrase IV and XIV, and an electroneutral bicarbonate co-transporter NBCn1. We have also shown that inhibiting the function of these proteins has a significant impact on bone resorption and osteoclast morphology. Furthermore, we have explored oxidative metabolism in chondrocytes and found that carbonic anhydrase III (CA III), a protein linked to the prevention of protein oxidation in muscle cells, is also present in mouse chondrocytes, where its expression correlates with the presence of reactive oxygen species. Thus, our study provides novel information on the regulation of cellular metabolism in calcified tissues.

Parenteral administration of vitamins A, D and E on the oxidative metabolism and function of polymorphonuclear leukocytes in swine

The weaning period of piglets is characterized by physiological alterations, such as decreased weight gain, increased reactive oxygen species (ROS) and increased serum cortisol levels with possible effects on the immune response. The effect of parenteral administration of vitamins A, D and E on production performance, oxidative metabolism, and the function of polymorphonuclear leukocytes (PMNLs) was assessed in piglets during the weaning period. The sample was comprised of 20 male piglets that were given an injectable ADE vitamin combination (135,000 IU vitamin A, 40,000 IU vitamin D and 40mg vitamin E/ animal) at 20 and 40 days of age. Weight gain, concentration of reduced glutathione (GSH), malondialdehyde (MDA), superoxide dismutase (SOD) and the microbicidal and phagocytic activity of PMNLs were assessed. No difference was observed in the average piglet weight during the study; however, a greater percentage of weight gain was observed after weaning in the treated group. The concentrations of GSH and SOD did not differ between groups, although lipid peroxidation was greater in the control group at 60 days of age. The investigated variables of oxidative metabolism were correlated as follows: -0.41 for GSH and MDA, -0.54 for GSH and SOD and 0.34 for MDA and SOD. The intensity of intracellular ROS production, the percentage of ROS-producing PMNLs and the intensity of phagocytosis by PMNLs did not differ between treatment groups. Administration of the injectable ADE combination improved the percentage of weight gain between 20 and 40 days of age, decreased oxidative stress at 60 days of age and did not influence the function of PMNLs in piglets.

Oxidative metabolism and muscle biochemical profile of polo horses supplemented with an ADE vitamin complex

Horses used for the game of polo experience abrupt and frequent changes in exercise intensity. To meet this variable energy demand, the horses use both aerobic and anaerobic pathways in varying proportions and intensities. In this context, there must be a balance between the formation of reactive oxygen species (ROS) and the action of antioxidants to prevent oxidative stress and its consequences. The effect of supplementation with an ADE vitamin complex on oxidative metabolism was evaluated in 18 crossbred horses randomly divided between a treated group (TG) and a control group (CG). The TG animals received the ADE vitamin complex (1mL/50 kg of body weight) by deep intramuscular injection at 30 and 15 days before the game. The CG horses received 10ml of saline by the same administration route and schedule. During the polo match, the animals played for a total of 7.5 min. Blood samples were collected on the same days as the treatments were administered, and immediately before and at 15, 90 and 180 minutes after the game. The concentrations of creatine phosphokinase (CK), lactate dehydrogenase (LDH), lactate, glucose, aspartate aminotransferase (AST), glutathione (GSH), superoxide dismutase (SOD) and malondialdehyde (MDA) were measured in the blood samples. After the game, the TG demonstrated higher levels of AST, lactate and glucose than the CG, suggesting more efficient energy use by the treated animals. The higher GSH and lower lactate levels in the TG before the game suggest the presence of a greater antioxidant supply in the treated animals. The maintenance of the MDA levels indicates that neither of the groups exhibited oxidative stress.

Effect of melatonin on the oxidative metabolism of colostrum phagocytes of diabetic women

Aim: the aim of this study was verified the ability of melatonin hormone to modulate the oxidative metabolism of colostral phagocytes from diabetic mothers. Methods: based on 100g-OGTT and glucose profile analysis subjects were allocated into two groups: Non-diabetic (ND-10) and Diabetic (DM-8). Cells were separated by a Ficoll-Paque gradient and the oxidative metabolism was available thought superoxide release by colostrum phagocytes using the cytochrome C method. Results: melatonin hormone increased superoxide release by colostrum phagocytes of ND and decreased these release in colostrum phagocytes of DM mothers. Conclusion: the results suggest that the melatonin hormone can modulate the oxidative metabolism of phagocytes and an existence of relationship between control of glucose metabolism and melatonin action in colostrum phagocytes.

Oxidative metabolism of the neutrophils in sheep treated with sodium monensin and experimentally submitted to ruminal acidosis.

Ruminal acidosis is due to excessive ingestion of carbohydrates of rapid fermentation without previous adaptation of the microorganisms, causing severe metabolic disturbances to the animals. The objective of the present study was to assess the neutrophilic oxidative metabolism in sheep treated with sodium monensin in experimentally induced ruminal lactic acidosis. A total of 18 male sheep, half-bred (ideal x Merino), fistulated in the rumen, were used; nine of them received 33 mg/kg of the ionophore diet per day, for 30 days; the others were controls. The acidosis was induced by supplying 15g of sucrose/kg of body weight. The clinical evaluation and the rumen and blood samples were obtained before (0h) and at 6, 12, 24 and 48 hours post-induction. In both groups, all the animals presented clinical manifestations of ruminal lactic acidosis 6 hours after the induction. From this period on, a significant pH decrease (P<0.05) was observed in the ruminal fluid, which reached levels below 5. There were relevant differences (P<0.05) between the groups 12 hours after the induction, when the sheep treated with monensin had higher values than those of the control group. During this period, the oxidative metabolism of the neutrophils remained inhibited, and the reestablishment of this function only occurred in the sheep which received monensin. Blood pH, plasmatic glucose and the ionizable calcium suffered alterations within its levels. The seric cortisol concentration rose significantly (P<0.05) in both groups, although differences (P<0.05) between them were found at the end of the observation period. The treatment with monensin did not influence the oxidative metabolism of the neutrophils inhibited by the lactic acidosis; however, a faster recovery of this metabolism was verified in the animals treated with the ionophore.

Interleukin-15 augments oxidative metabolism and fungicidal activity of human monocytes against Paracoccidioides brasiliensis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

5-AMINOLEVULINIC ACID-INDUCED ALTERATIONS OF OXIDATIVE-METABOLISM IN SEDENTARY AND EXERCISE-TRAINED RATS

5-Aminolevulinic acid (ALA), a heme precursor that accumulates in acute intermittent porphyria patients and lead-exposed individuals, has previously been shown to autoxidize with generation of reactive oxygen species and to cause in vitro oxidative damage to rat liver mitochondria. We now demonstrate that chronically ALA-treated rats (40 mg/kg body wt every 2 days for 15 days) exhibit decreased mitochondrial enzymatic activities (superoxide dismutase, citrate synthase) in liver and soleus (type I, red) and gastrocnemius (type IIb, white) muscle fibers. Previous adaptation of rats to endurance exercise, indicated by augmented (cytosolic) CuZn-superoxide dismutase (SOD) and (mitochondrial) Mn-SOD activities in several organs, does not protect the animals against liver and soleus mitochondrial damage promoted by intraperitoneal injections of ALA. This is suggested by loss of citrate synthase and Mn-SOD activities and elevation of serum lactate levels, concomitant to decreased glycogen content in soleus and the red portion of gastrocnemius (type IIa) fibers of both sedentary and swimming-trained ALA-treated rats. In parallel, the type IIb gastrocnemius fibers, which are known to obtain energy mainly by glycolysis, do not undergo these biochemical changes. Consistently, ALA-treated rats under swimming training reach fatigue significantly earlier than the control group. These results indicate that ALA may be an important prooxidant in vivo.